Design of top of the range ceramic cooktop with emphasis on usability and interface

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(1)2006:117 CIV. MASTER'S THESIS. Design of Top of the Range Ceramic Cooktop With Emphasis on Usability and Interface. Lina Andersson Marie Lindström. Luleå University of Technology MSc Programmes in Engineering Ergonomic Design and Production Engineering Department of Human Work Sciences Division of Product Design 2006:117 CIV - ISSN: 1402-1617 - ISRN: LTU-EX--06/117--SE.

(2) Design of top of the range. Ceramic Cooktop with emphasis on usability and interface. LINA ANDERSSON MARIE LINDSTRÖM 2006-04-05. MASTER OF SCIENCE PROGRAMME Department of Human Work Science Division of Industrial Design.

(3) Foreword. The possibility to do this master’s thesis in Australia is an outcome of collaboration between Luleå University of Technology and the CAMR institute at the University of South Australia in Adelaide. The collaboration has been going on since 1999 and the opportunity is given to students studying engineering towards either ergonomic design or production. This project would not have been able to carry out as well as it did if it would not have been for the help from a lot of people. Those who have been this helpful deserve recognition, so therefore, thank you… … Michael Jonas, supervisor at Electrolux, Tony Hanson and Justin McLindin for showing a great interest in our work, giving good support, helping out gathering information and giving feedback and comments about the work. … everyone at the quality department for support and help. … Erno Jo and Chris Baxter at the electrical engineering department for advice and assistance during the electrical testing. … Margaret Kirkwood, home economist and test cook at Electrolux, for a good insight in cooking tradition and trends. … Christine Gall and Andrew Reade at the Design Centre in Sydney, for help regarding the interface. … workers at the assembly line of ceramic cooktops at the cooking plant in Dudley Park for patience in answering questions. … Electrolux sales personnel through Leanne Hague, for opinions and for being the link to retailers. … fellow students from Luleå for their advice and feedback. Especially Johnny Bjuhr, Fredrik Kogerfelt, Emelie Svensson and Robert Viklund. … Bob Speedie and Evangelos Lambrinos, at UniSA, who organized the placement. … Åsa Wikberg, supervisor at Luleå University of Technology, for support and feedback during the project. … Stig Karlsson and the Institute of Work Science for financial support.. Pleasant reading!. ______________________________. ______________________________. Lina Andersson. Marie Lindström.

(4) Abstract. This project’s aim is to develop a ceramic cooktop for the premier market suitable to be sold in Europe, America, Asia and Australia. The final concept is a ceramic cooktop that with as high profit margin as possible for Electrolux also appeals the most for high-end consumers from all over the world. Today ceramic cooktops from different producers have aesthetics very similar to each other and it is hard to differentiate one brand from another. Therefore by designing a cooktop that stands out from the rest, Electrolux’s aim to get in to the premier segment of the market and to profile itself there, would be possible to reach. A problem that soon was noticed was that the interface of cooktops often is very hard to understand and that the control panel technique can be experienced as unreliable. So, emphasis was, besides making an original design, also laid on making the cooktop as user friendly as possible. Facts and information about components were thoroughly read to get a good understanding of the product. Theory about how to make a proper benchmarking and also theories about symbols and gestalts were studied. Following and parallel to this, a systematic development work was conducted by further investigating the actual problem and customer needs. Kitchen standards all over the world were mapped to find out what dimensions the cooktop should have. The result of this was the benchmark form and the product specification. The benchmarking was then carried out by comparing cooktops made both by Electrolux and other producers. By following the benchmark form to grade each cooktop, conclusions about the design were made. User tests on the cooktops gave additional information about usability and interface issues. Dividing the design into sub areas in a screening matrix and brainstorming about these led to a wide range of ideas. The solutions to each area were then combined in different ways to create the best concepts. To choose one concept the necessity of desired criteria’s were weighed against each other and then the concepts were scored by how well they fulfilled those. All this led up to the final concept, the Clear Cooktop. The dimensions of Clear are suited to fit the selected markets as good as possible. It has a smooth and easy to clean top surface consisting of two different types of ceramic glass, black above the elements, and a frosted clear glass piece where the control panel is. The control panel and the interface are developed with capacitive touch control technique in mind. This is a more reliable technique than the techniques used in existing cooktops. The interface, the new control panel technique and the unique combination of two different ceramic glasses will for sure make the cooktop stand out on the market.. 2.

(5) Definitions. To make the report easier to understand the following definitions are made. Ceramic glass Control panel Cooking zone / zone Cooktop Cooktop features Element Element layout Key Knob Slide Touch control. – the glass covering the top of the cooktop. Is special because it does not expand by heat. – the area on the cooktop where all the keys are and all the settings are made. – the circular area that is heated while cooking. Each element can have one or more zone sizes, then called dual- or triple zone. – a kitchen appliance for cooking food. Installed in a workbench with no owen. – what functions and different settings that can be made on the cooktop. In section 3.3.5.1 each feature is thoroughly explained. – the heat generator. Placed below the ceramic glass. Consist of one or more zones. – how the elements are placed on the cooktop. – can be a button, touch sensor, slide etc. Everything where an adjustment can be made. – one type of key. Adjustments are made by turning it. – one type of key. Adjustments are made with a sliding motion. – one type of key. Adjustments are made by touching the finger in the key area.. 3.

(6) Table of content 1. INTRODUCTION. 7. 1.1 Background 1.1.1 Electrolux Home Products Pty Ltd 1.1.2 Current situation. 7 7 7. 1.2. Purpose of project. 8. 1.3. Project objectives. 9. 1.4. Constraints. 9. 2. THEORY. 10. 2.1 Benchmarking 2.1.1 Reasons for benchmarking 2.1.2 Teardown process 2.1.3 Benchmarking approach 2.1.4 Setting product specification. 10 10 10 11 12. 2.2. Element technology. 12. 2.3. Ceramic glass. 13. 2.4 Control panel techniques 2.4.1 Touch control 2.4.2 Knobs 2.4.3 Magnetic point and twist control. 13 13 15 15. 2.5 Interface & symbols 2.5.1 The proximity factor 2.5.2 The inclusion factor 2.5.3 The area factor 2.5.4 The good curve (determining factor) 2.5.5 The common movement 2.5.6 The similarity factor 2.5.7 The symmetry factor 2.5.8 The experience factor. 15 16 16 16 16 17 17 17 17. 3. METHODS. 18. 3.1 Systematic development work 3.1.1 Pre phase 3.1.2 Concept generation 3.1.3 Concept selection. 18 18 18 18. 3.2 Pre study 3.2.1 Problem analysis 3.2.2 One day at the assembly line 3.2.3 Function analysis 3.2.4 Structure of functions 3.2.5 Sub problems 3.2.6 Customer needs 3.2.7 Restrictions. 19 19 20 20 21 21 23 24. 4.

(7) 3.2.8 3.2.9. Benchmarking User test. 28 29. 3.3 Concept generation 3.3.1 Brainstorming 3.3.2 Concept combination table 3.3.3 Cooktop shape concepts 3.3.4 Element layout concepts 3.3.5 Interface concepts. 31 31 31 33 36 37. 3.4 Concept selection 3.4.1 Criteria weighting 3.4.2 Concept scoring 3.4.3 Winning concepts. 43 43 45 46. 4. RESULTS. 48. 4.1. Features. 48. 4.2. Cooktop shape. 49. 4.3. Element layout. 53. 4.4. Interface. 55. 4.5. Price. 62. 4.6. Marketing. 62. 5. DISCUSSION. 64. 5.1. Project. 64. 5.2 Methods 5.2.1 User test 5.2.2 Benchmarking. 64 64 64. 5.3 Results 5.3.1 Manufacturing. 65 65. 5.4. 65. Continuation. Literature. 66. Web. 66. People. 67. APPENDIXES Appendix 1 Appendix 2 Appendix 3 Appendix 4. Assembly line – ceramic cooktop Benchmark form Benchmark form – one cooktop Explanation of benchmark form. 5.

(8) Appendix 5 Appendix 6 Appendix 7 Appendix 8 Appendix 9 Appendix 10 Appendix 11. User test User test - results Criteria weighting Concept scoring - cooktop Concept scoring – element layout Product brief Bill of material. 6.

(9) 1 Introduction 1.1 Background 1.1.1 Electrolux Home Products Pty Ltd Electrolux is the world’s largest producer of powered appliances for kitchen, cleaning and outdoor use, for instance refrigerators, washing machines, cookers, vacuum cleaners, chain saws, lawn movers and garden tractors. The Electrolux Group includes famous appliance brands such as AEG, Electrolux, Zanussi, Frigidaire, Eureka and Husqvarna. Electrolux’s products are at work in over 400 million homes in more than 150 countries around the world. Globally, Electrolux sells, on average, two appliances every second, every day. The Electrolux group employs 72,000 employees world wide and 3,300 in Australasia, which is Australia and Asia. In Australasia, Electrolux is the leading whitegoods company through its Australian and New Zealand subsidiaries, Electrolux Home Products Pty Limited and Electrolux Home Products (NZ) Limited. Whitegoods manufactured in Australasia by Electrolux are marketed under Westinghouse, Simpson and Electrolux-Chef, Dishlex, Kelvinator brands and, for export markets, under other brands. The company’s four manufacturing plants in Adelaide produce cookers, range hoods, washing machines and dryers, dishwashers and appliance motors. The manufacturing plant in Orange, 250 km west of Sydney, produces refrigerators and freezers. A further plant in Christchurch, New Zealand, producers cookers. Electrolux imports into Australia and New Zealand kitchen and laundry products from Europe which it markets under the Electrolux Gallery brand. 1 Electrolux produces about 600,000 ceramic cooktops a year and is competing with a large number of other brands on the cooktop market all over the world. Now Electrolux put extra emphasis on building the brand even stronger by having a larger presence in the premier segment of the market.. 1.1.2 Current situation Electrolux currently does not have a top of the range ceramic cooktop model, however, the Westinghouse model PHL768U is considered the best in Electrolux’s product range in Australia, see Figure 1.. 1. www.electrolux.com.au. 7.

(10) Figure 1. Top view of Westinghouse PHL 768U.. The Westinghouse model is made at Electrolux’s cooking plant in Dudley Park, Adelaide, together with three other Electrolux brands: Electrolux, Electrolux CHEF, Westinghouse and Simpson. The models are made in short series and there are a total of 16 of them. An overview of the element and control panel layout of these can be seen in Figure 2.. Figure 2. Element and control panel layout.. The Europe-based Gallery brand is also considered a top of the range product family with cooktops, ovens and range hoods. However, it has not been selling as well as Electrolux wanted so something needs to be done.. 1.2 Purpose of project Today the wide range of cooktops gives a fairly homogenous impression, hence a cooktop that can be sold throughout the world and differentiate itself from competing cooktops will become a good investment for Electrolux. The purpose of this project was to develop such a cooktop. This project also acted as an opportunity to use knowledge collected throughout the education at Luleå university of technology.. 8.

(11) 1.3 Project objectives The objective of this project is to develop an electric ceramic cooktop aimed at the premier end of the market suitable to be sold in the European, American and Australian markets. The final result of the project is a product brief giving a detailed description of styling, size, cost, selling price, volume etcetera with supporting information. Theory, methodology, work process, different design concepts, analyses and results are presented in this report.. 1.4 Constraints Our focus is the useability, styling, shape and function of the cooktop. No engineering drawings are made, although, the manufacturability is taken into consideration and major parts will be defined. Assembly and packaging methods, transport issues and the layout of a user manual are not addressed.. 9.

(12) 2 Theory 2.1 Benchmarking Benchmarking is one type of reverse engineering. In this project both Electrolux’s own cooktops as well as competing products were examined.. 2.1.1 Reasons for benchmarking When it comes to development of a product, the producing company would want to take a look at other products and producers to see what already is available on the market. Markets all over the world and a lot of different market segments should be considered to find a suitable group of products to be compared. A benchmark can be done in several different levels of intensity, from just comparing different products subjectively, to really tearing the products apart and investigate how they are manufactured and exactly how they function. Systematic forms and methodology can be helpful in the latter case.. 2.1.2 Teardown process To get a good result of a benchmarking process it is important that the teardown of the products is done the right way. Following is a typical teardown process 2 : Step one, list design issues Find out what problems and opportunities the previous design team has had. What was difficult for them? What design problem did they solve that they are proud of? What related technologies were they interested in? It is important to focus on the “what” before the “how” to be able to make a good benchmarking. What are the products in the benchmarking intended to do? A function structure is a good assistance to uncover these design issues. There are some basic factors that are typically needed to be known: . Quantity of parts per product unit Dimensional measurements Maximum, minimum, and average material thickness Weight Material Colour/finish Manufacturing process, including sufficient information for a Design for Manufacturing analysis Geometric, spatial, and parameter tolerances Primary functions Cost per part or subassembly. 2. Teardown Process, p.200-208, ‘Product Design – Techniques in Reverse Engineering and New Product Development’. 10.

(13) . Other notes. Step two, prepare for teardown Identify all tools that will be required to complete teardown including sensors, test equipment, etc. Step three, examine distribution and installation The distribution packaging, consumer installation instructions and procedures are being examined for costs, effectiveness, and liability. Step four, disassemble and measure For this step to be effective it is important to coordinate it with measurements and experimentation. First, take a picture of the whole assembly and then: . Take apart the assembly Take pictures in an exploded view (and/or produce a solid model assembly diagram – electronic exploded view) Take measurements of the parts and assemblies to complete the data sheets. It is important to be careful at this step so that the product can still function. Later on further teardown might be necessary where destructive testing is needed. Step five, form a bill of materials Complete a written form, a Bill Of Material, that details the product. Data collected in each column are that required for subsequent analyses, including cost and performance.. 2.1.3 Benchmarking approach When benchmarking, the teardown process is done to several products. It is important that the information is gathered so it is easy to compare. To do this right there are, in the same way as the teardown process, different steps to follow 3 . These are as follow: Step A, form a list of design issues Focus on the design issues that are the most interesting for the benchmarking process and continually revise and update it. Step B, form a list of competitive or related products From the list of design issues, the market is scanned to find other producers with competing products. Once this is done all related producers and their products are listed to find out preferred market segments. This list is then screened to highlight the particular competitors that are most interesting for further investigation. Step C, conduct an information search The investigation goes on by using the internet, library and other sources of information. It is important to know as much as possible about the products, related products, their key functions and their target market segments.. 3. Benchmarking and establishing engineering specifications, p.262-269, ‘Product Design – Techniques in Reverse Engineering and New Product Development’. 11.

(14) Step D, tear down multiple products in class Follow the teardown procedure described earlier to create an indented bill of material, a functional model for each product, an exploded view of each product and the function-to-form mappings of the functions to the assemblies. Each function should have measured performance levels completed. Step E, benchmark by function To be able to compare the benchmarked products, one approach is to summarize all different ways a function can be designed. This makes it easy to differentiate functions. Step F, establish best-in-class competitors by function By looking at the list of functions the highest performing one can be described as best-in-class. Also the least expensive one can be called out. Step G, plot industry trends It is important to keep in mind what type of product that should be designed. Market segments, product performance and product profile.. 2.1.4 Setting product specification The final outcome of the benchmarking process is a specification 4 . The specification contains the required levels of performance for the new product.. 2.2 Element technology The cooking zones on the ceramic cooktop are heated by elements placed under the glass. The ones that the market prefers today are ribbon elements, and these can vary in size (single-, dualor triple zone), shape (round or oval) and efficiency. Different features, such as pan/pan size detection and quick heat-up, can also be added to the elements. A ribbon element consists of a heater ribbon placed on a thermal insulation plate and surrounded by an insulation ring. The ingoing effect to the element is controlled by a “limiter”, a thermostat, which switches the power to the heater on and off to keep the pre-set effect. That is, it does not measure the temperature. 5 In Figure 3 an example of an element is seen.. Figure 3. A one zone element made by EGO.. Benchmarking and establishing engineering specifications, p.274-283, ‘Product Design – Techniques in Reverse Engineering and New Product Development’ 5 Martin Ward, Ceramaspeed 4. 12.

(15) The market of ribbon elements is quite limited and there are three main producers: Ceramaspeed, EGO and Eika. The design and style of the models of the different brands are basically the same, and only differs in sizes and combinations possible. Ceramaspeed is Electrolux’s current supplier.. 2.3 Ceramic glass Ceramic glass is used as the top surface of cooktops because of its characteristics. When heated it neither expands nor contracts though it is a good heat conductor. The glass is made by a liquid that is rolled into a sheet, then annealed at a temperature of 700°C and cut in big rectangles. The next step in the production is to adjust it to the customer demands by cutting it down to the right size, shaping the edges, printing cooking zones and coloured surface decorations. Finally it is heated to a temperature of 900° C to make it into a ceramic glass. 6 The glass can be made transparent or with a black or white colour. However, the transparent one has other properties than the black and white and cannot be placed directly above the elements when having an electric heating. However, when using induction heating it is possible. Moreover, it is possible to choose between about 30 different colours for the decoration which is screen printed on the glass. The thickest glass possible is 4 mm and it is not possible to make glass with varying thickness. Depending on thickness and decorations, the glass can transmit lights with wavelength from the infrared area up to 1600 nm. 7. 2.4 Control panel techniques 2.4.1 Touch control There are several techniques, on the market, in recognising a stimulus as a touch and a command. Today Electrolux uses infrared technology for this, but there are several alternative techniques available, such as temperature, capacitance, resistance, radio reception and surface acoustic wave technology. The touch control sensors are placed beneath the ceramic glass as in Figure 4.. Figure 4. LG Cooktop with touch control. 6 7. www.schott.com Lars Bergman, Schott. 13.

(16) 2.4.1.1 Temperature The technology relies on buttons that are sensitive to the warmth of the human finger. These buttons does not work if your hands are cold. 8 2.4.1.2 Capacitance Capacitance is the capacity an object has to hold electrons. The cooktop has a certain capacitance, and this means that if a circuit tried to charge the cooktop with electrons, it would take a certain number to ‘fill it’. When you touch the control, your body adds to its capacity. It takes more electrons to fill you and the element, and the circuit detects that difference. This means that you need to use your finger to make the system register a touch. The sensors are not heat sensitive, since it only senses the body’s capacitance to earth, and continually self calibrates to the surroundings. 2.4.1.3 Resistance The human body conducts electricity fairly well. By placing two contacts close together, your finger can close the circuit when you touch it. Another explanation of the resistive system, when used as a touch screen, is that it consists of a normal glass panel that is covered with a conductive and a resistive metallic layer. The two layers are held apart and a scratch-resistant layer is placed on top. An electrical current runs through the two layers, and when you touch the screen the two layers make contact in that exact spot. The change in the electrical field is noted and the coordinates calculated. 9 The resistive system registers a touch as long as the two layers make contact, which means that you can use your finger as well as a rubber ball. 2.4.1.4 Radio reception The human body acts like a good antenna and some touch-sensitive switch designs look for a change in radio-wave reception that occurs when the switch is touched. 2.4.1.5 Infrared technology A grid of infrared light covers the surface that is used as a touch screen. The touch screen frame contains a row of IR-light emitting diods (LEDs) and photo transistors, each mounted on two opposite sides to create a grid of invisible infrared light. The grid is located in front of the display screen and when you touch the screen, its beams are interrupted. One or more photo transistors from each axis detect the absence of light and transmit signals that identify the x- and ycoordinates. 2.4.1.6 Surface Acoustic Wave technology Surface Acoustic Waves, SAW, are used in touch screens which act as digital maps of the surface. On the x- and y-axis there are transmitting and receiving transducers and a set of reflector stripes on the outside edge of the screen. The touch screen sends a burst to the transmitting transducers that convert the electrical signal into surface acoustic waves, mechanical waves that propagate in the surface of materials such as glass. A special pattern of reflector stripes diverts the burst to create a uniform density of acoustic wave energy across the surface of the screen. 8 9. http://home.howstuffworks.com http://electronics.howstuffworks.com. 14.

(17) The soft touch with a finger absorbs a portion of the wave, and the resulting change in the received signal is converted into x- and y-coordinates. SAW is the only touch technology that can also sense the pressure of a touch. 10. 2.4.2 Knobs Knobs are used in several cooktop models made by all brands. Their style varies from the most common to more contemporary, se one example in Figure 5.. Figure 5. Electrolux model with knobs. 2.4.3 Magnetic point and twist control A magnetically centred control knob can be used instead of ordinary knobs. Every turn of the magnetic knob is tracked by a magnetic field sensor and the actual setting can be read off a bar graph or a 7-segment display. 11 The knob is removable. This technique is used in cooktop models from Bosch and Neff, see Figure 6.. Figure 6. Gaggenau model with point and twist control.. 2.5 Interface & symbols Designing an interface is all about making it as fail proof as possible. One way of doing this is to use gestalts. A gestalt is defined as an arrangement of parts that appears and functions as a whole 10 11. http://electronics.howstuffworks.com http://www.egoproducts.com. 15.

(18) that is more than the sum of its parts. So, form, colour and material structures are experienced in a way where they work together and influence each other rather than seen as isolated factors. To easier understand what makes a gestalt design factors are defined. The factors are good guidelines to follow when designing the interface and its symbols. In the following sections the factors are described. 12. 2.5.1 The proximity factor Objects that are close together give the impression of belonging together, see Figure 7.. Figure 7. The squares are seen as two gestalts.. 2.5.2 The inclusion factor Objects/lines that almost make a shape are perceived as that shape, see Figure 8.. Figure 8. Seeing the lines together gives the perception of a square.. 2.5.3 The area factor Enclosed areas create gestalts and the smaller the area is, the easier it is for the human to experience it as gestalt.. 2.5.4 The good curve (determining factor) Objects, lines for instance, that are close to one another and make minimum change or break can be seen as a semi-completed curve, see Figure 9.. 12. ”Design for Product understanding”. 16.

(19) Figure 9. Four of the lines in the figure may appear as part of a curve and together make a gestalt.. 2.5.5 The common movement Objects that are following the same direction and motion can be seen as a group compared to the surroundings. An example of this is the two gestalts created by the two directions in which cars move on a motorway.. 2.5.6 The similarity factor Objects that look the same are seen as a group or shape.. Figure 10. The thick lines make one group and the thinner lines another.. 2.5.7 The symmetry factor Objects with symmetry make gestalts.. 2.5.8 The experience factor To be able to recognize a gestalt it must be observed in the way it has been learnt by experience. For example it can be hard to recognise an object in an environment where it is usually not seen.. 17.

(20) 3 Methods 3.1 Systematic development work The development work has been conducted supported by systematic methods to make sure everything is taken into consideration and that choices and decisions are as objectively made as possible. 13. 3.1.1 Pre phase 3.1.1.1 Problem analysis A way to analyse the problem at hand can be done through answering a number of key questions or through breaking down the problem into simpler sub problems and it may be easier to understand. 3.1.1.2 Function analysis The functions performed by a product can systematically be analysed through a product function analysis where the functions of the product is listed, as they are perceived by the customer. The sub problems from the previous problem analysis can be used here. 3.1.1.3 Customer needs The more the developer interacts with customers and the use environment of the product, the more he/she will understand the needs for the product. 14. 3.1.2 Concept generation 3.1.2.1 Brainstorming In Brainstorming, knowledge from a group of people is used, preferably of different background, to generate solutions to the sub problems. The group meeting is essential for this creativity. 3.1.2.2 Concept combination table Solutions to the different sub problems are listed in the concept combination table, and are then combined to provide new concepts. This is a way to display new combinations and broaden ones mind.. 3.1.3 Concept selection To maintain objectivity throughout the concept phase, a structured method for concept selection can be used. Concept screening provides support when making simpler design decisions and concept scoring helps to differentiate the concepts further. For this two matrixes are used to rank, rate and in the end select the best concept. ‘Engineering Design – A Systematic Approach’, ‘Product Design and Development’ and ‘Product Design: Practical methods for the systematic development of new products’. 14 ‘Product Design and Development’ 13. 18.

(21) 3.2 Pre study A great deal of information has been collected through different medias such as web sites of home appliances producers and other helpful web sites on the internet, books from the UniSA Library, reports provided by Electrolux, product catalogues and more. One day was also spent working on the assembly line of the ceramic cooktops, which included wiring, screwing and mounting parts in the right way. All of this was made to complete the picture of the cooktop market and to learn more about the important cooktop components and possible ways of development.. 3.2.1 Problem analysis To clarify what the problem is really about a number of questions are answered: What is the problem really all about? To design a cheaper cook top with as high quality and top of the range appearance as possible. What expectations and desires are included? Make the cook top attractive for high end users and at the same time raise the profit margin. The cook top is supposed to be the leading one on the market and suit the different kitchen standards of the world (European, American and Australian markets). Are all demands really necessary? To be able to fit the different kitchen standards of the world, is not realistic. What tasks should the product be able to do? Cook food. Support pans and pots. Which ways are open for development? Layout, shape, materials, number of parts, controls, colours, dimension, cooktop placement, user interaction etc. What features should the product hold? Safe, attractive, understandable, child proof, efficient, high quality, easy to clean, ergonomic, be adjustable to different countries needs. What features should the product NOT hold? Dangerous, unstable, unreliable, breakable. Are there similar products/solutions? How is the current level of technology? Similar products are all over the world. Miele, Smeg, Gaggenau, LG, Dacor, GE, Neff, Siemens and more are all producing electric ceramic cooktops at the premier end of the market. Almost all uses touch control systems, in some of their models, and several features are the same, for example cooking programs. Are there standards? (Legislations, laws etc) Electrical, waterproof, environmental and different kitchen standards through out the world. Mainly North American and European differ from Australia, but there are similarities between Europe and Australia. . What possibilities should there be for the user to change the design/function?. 19.

(22) To change the heat, take time, size of cooking zone, set cooking programs and other special cooking functions. What technical trends/possibilities for development/aesthetical trends, are there? There are new kinds of controls, capacitive and magnetic forced, as well as the most common infrared touch controls, where the interface most certainly can be made easier to use. Furthermore the glass can be made in different thicknesses, patterns and colours. Previous answers are summarised as an abstraction:. ‘An electric ceramic cooktop which appeals to high-end consumers all over the world, and holds a higher profit margin than before. Its unique styling helps attract attention to Electrolux and build the brand stronger.’. 3.2.2 One day at the assembly line To get more information and insight about the ceramic cooktop and its components, one day was spent on the assembly line of ceramic cooktops. Mounting, screwing and wiring made the picture much clearer when it came to what the cooktop is made of. A description of the assembly process can be found in Appendix 1. Assembly line – ceramic cooktop.. 3.2.3 Function analysis To get an overview of possible functions in a cooktop a function analysis was done. The fragment functions are the functions building up the main function. The sub functions are separate and not necessary for the main function, but they enhance the product value.. Main function . Cook food. Fragment functions . Turn on/off Enable heat change Warm up pan and contents Support pan and contents Stabilise pan and contents. Sub functions . Enable zone size variation Enable zone shape variation Give information about residual heat Give information about temperature Give information about program settings Give information about faults Enable personalised information settings Enable time setting Enable time setting for specific cooking zone Enable programmed cooking. 20.

(23) . Enable small heat variations Enable high heat settings Enable low heat settings Enable quick warm-up Be child safe Shut down if not in use Feel presence of pans Feel size of pans Feel spill on control panel Prevent spilling outside cooker (trim) Enable easy installation Enable easy manufacturing Enable easy usage. 3.2.4 Structure of functions In the previous function analysis the main function of the cooktop, cook food, was divided into fragment functions. Through these fragment functions there is a flow of energy and signals and to get a further understanding of these functions a schematic structure was made., see Figure 11. Energy Signals. S1. S2. S3. S4. Figure 11. Structure of functions. S1, S2, S3 and S4 are the different sub functions and the lines represent the flow of energy and signals through them.. S1 = Turn on/off S2 = Enable heat change S3 = Warm up pan and contents S4 = Support and stabilize pan and contents. 3.2.5 Sub problems Information from previous projects can be used to reinforce the problem already discovered. One description of two big problems 15 in cooktops are:. 15. ‘Problem detection and insight generation: Built-in cookers and cook-tops’. 21.

(24) 1. Cooktop easily scratched/hard to keep clean Stainless steel is surprisingly vulnerable and easily scratched Stainless steel also gets greasy or ‘smudgy’ ruining the ‘look’ Ceramic cooktops were found to be harder to clean than anticipated (scraper and specialised cleaner/polish required). Also, spills on ceramic tops required immediate attention to avoid becoming permanent 2. Spacing and size of elements Cramped conditions a large source of frustration Secondary safety concerns Results in pot swapping (can be dangerous with heavier pots) Can make cooking process longer (waiting for an appropriate burner to be available) This was kept in mind during the development process. The main function can also be separated into fragment functions and sub functions, however, the entire problem in itself, can be divided into sub problems to make it easier to solve. Except deciding what features to include in the cooktop, the following sub problems must be solved. 3.2.5.1 Cooktop shape Shape Edge/trim Material 3.2.5.2 Element layout Element layout Number of elements Element type, supplier 3.2.5.3 Interface Zone placement indications Zone symbol Zone size adjustment Zone size indication Timer symbol and adjustment Timer indication on zone Program symbol and adjustment Program indication on zone Temperature symbol and adjustment Quick heat-up symbol and adjustment Temperature indication on zone Zone on-indication Residual heat indication Cooktop on/off key Cooktop on/off indication 22.

(25) . Child lock Pan- and pan size detection indication/key Fault display/information Control panel type Control panel placement Control panel layout. 3.2.6 Customer needs To find what are the needs of the customers, several visits to retailers were made, and a large number of people with different interest in cooktops were spoken to. Moreover, Electrolux has published a folder 16 where typical AEG, Electrolux, Westinghouse and Simpson customers are described. In this project the portrayal of the AEG consumer has been used to describe the user for the new Electrolux cooktop.. “AEG consumer:. A couple with grown-up children. He is an architect and she runs her own catering company. They are both extremely exacting, demanding the very best in their home which he designed himself. All their appliances have been chosen for their aesthetics and superior performance.”. “Electrolux consumer:. Glen & Ella, a professional couple who are very proud of their accomplishments and extremely career focused. They have very active lifestyles and because of this they eat out 2-3 times a week. However, they also love entertaining friends and family at weekends. They surround themselves with stylish appliances and like to keep their home neat. Housework is fitted in around social activities and hobbies. They are willing to pay a premium for stylish appliances that have superior efficiency, deliver enhanced health and are easy to use.” Another research report 17 has described Electrolux’s profile segments as the Independent, Status/style conscious, Effortless help and Preparedness. These are described beneath and the report also states the different needs of each segment as follow. 3.2.6.1 Independent I want more time for me I want to get the most out of life Need for innovation ‘The cooktop needs to make me feel in control and give me the freedom, choice and flexibility so that I can be a grand entertainer one day and a regular cook the next.’ Segment needs are the aesthetics, an efficient performance, innovation to make life easier, that it is contemporary and simple to use. 3.2.6.2 Effortless help Duty to care for others I want to do things quickly 16 17. ‘Your guide to Australia’s brands’ ‘Problem detection and insight generation: Built-in cookers and cook-tops’. 23.

(26) . Need to make life easier. ‘The cooktop needs to look good, be efficient, fast and reliable, require minimal maintenance and provide a hassle free experience.’ Segment needs are easy cleaning, simplicity of operation and that it is seen to be a good choice. 3.2.6.3 Preparedness I need order and planning I want practicality No-one/thing does it as well as me Segment needs are easy cleaning, simplicity of operation, an efficient performance, good quality and that it is durable and practical. 3.2.6.4 Status/style conscious I want to impress I want the very best – European I need control ‘The cooktop needs to live up to its image and look good and reflect my dual need for an attractive yet functional space of which I can feel proud.’ The status/style conscious is the segment that fits the target user group the best and this segment’s needs are the aesthetics, space optimisation, performance efficiency, flexibility/adaptability and that it is creative and contemporary. The description of the user was discussed with supervisors and influential people at Electrolux and it all adds up to that the user is above 30 years old, has a lot of money and uses the kitchen to cook and impress. He or she installs the cooktop in a newly built kitchen or in some cases a renovated one. Features most relevant to the status/style conscious segment should be: . Stylish Practical and innovative designs in the context of entertaining Easy to clean Efficient Good quality/durable Electronic control. 3.2.7 Restrictions Project definitions say that the new top of the range cooktop should be sold throughout the world, which further is specified as the European, Australian and American markets. This, and other characteristics concerning the product design, are explored and specified in order to make a cooktop that truly meets the expectations.. 24.

(27) 3.2.7.1 Product specification The aspects of what increases the user’s interpreted value of the product, but is not necessary for the function, is called a desire. It is specified in the product specification, see Table 1, along with all the demands the product needs to fulfil. The product specification is written based on the benchmark form. Table 1. Demands and desires Demand. Desire. x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x. 1. Transport and packaging No special tools should be needed for unpacking Package should give impression of quality Cheap packaging method Environmental friendly packaging Environmental friendly packaging method Transport friendly shape Protective package 2. Geometry Visible area width = 600mm Glass thick enough to hold pans Glass transparent (thin) enough to let through light Optimal size and shape of glass for low cost Cut-out length >560mm Cooktop height above workbench low No sharp edges Easy to clean Optimal element sizes 3. Installation Only standard tools should be needed Easy to install 4. Functions Turn on/off Zone size variation Time setting Time setting for specific cooking zone Good heat variations Feel presence of pans Good empty surface usage Include simmer in one element 5. Signals Possibility to adjust signals Audio: Good warning sounds Good feedback sounds Good alarm sounds Visuals: Easy to see and interpret hot element warnings Easy to see and interpret timer Easy to see on/off indication Easy to see heat zone adjustment indication Easy to see temperature indication Easy to see indication of element layout when not in use. 25.

(28) x. Easy to see indication of element layout when in use Easy to understand control panel graphics Clear graphics Information about faults. x x x x x x x. 6. Style Easy to understand interface Design for disabled (hearing- and sight impaired) Language tolerant interface Top of the range appearance Quality-look Express safety Look expensive Look original. x x x. x. x x x x x x x x x x x x x x x x. 8. Safety Child-safe Safe placement of control panel Clear indication of hot areas Residual heat indication Safe placement of elements Safe control panel layout Cut-off function Waterproof Electrical safety 9. Forces No sunlight interference of control panel Good sensitivity in control panel. x x x x. 10. Materials Black ceramic glass Good quality of glass Smooth finish of glass surface Prevent scratches Low visability of scratches Low visabilaty of inside from outside. x x. 11. Maintenance Easy to disassembly Easy to uninstall. x x x x x. 12. Environment Recyclable Energy saving features Energy saving design Environmentally friendly manufacturing methods Minimum manufacturing waste. x x. x. 7. Ergonomics Easy to reach pots, element layout Easy to understand control panel Good size of keys Ergonomic control panel adjustment Good tactile feedback from cooktop surface. 13. Energy Time for cooldown < 55minutes from maximum heat to 30º C.. 26.

(29) x. Boiling time 6-8 minutes Quick heat-up. x x x. 14. Manufacturing High quality components Standard components High quality manufacturing. x x x. 15. Assembling Modular assembling Short assembly time Reduce number of part to a minimum. x x x x x x. 16. Costs Cost effective manufacturing Cost effective assembling Cheap parts Reduce transport costs Reduce need of maintenance Reduce labour costs. x. 3.2.7.2 Kitchen standards How many different standards are there in the world for kitchen dimensions? This is an intriguing question that is not very easy to answer. The kitchen standards throughout the world are getting more and more flexible and personalized to suit your home and needs. This means that it is getting harder to offer the world market only one dimension of a cooktop. The Swedish company IKEA have three different kitchen dimension standards, which is for Japan, North America and Europe. Australia and Europe must be considered by IKEA to be similar enough, because the same kitchens are sold in Australia as in Europe. The prioritised markets in this thesis are North America, Europe and Australia. The most common widths of cooktops in Australia are 600 and 900 mm, and they are about 490 mm deep. Guidelines say that the depth of a worktop should be 600 mm, also for people in wheelchairs who have elevated worktops. 18 The horizontal clearance from the back edge of a cooktop to a non-combustible wall surface or splashback e.g. tiles or granite, should be a minimum of 50 mm. 19 Horizontal clearance from any electric element or gas burner at the side of a cooktop to a combustible surface e.g. end panel, should be 300 mm. The 600 mm width goes well together with the common 600 mm ovens and dishwashers. Also the wall cabinet double doors from IKEA are 600 mm wide (optional 800 mm) for Australia and Europe. 20 These measurements goes well together with the ones on a couple of drawings of kitchen interiors provided from an architect company in Sweden, although they also show that it becomes more common to individualize the kitchen and show examples of both 600, 700 and 800 mm wide sections.. Appendix B, page 19 & 21, of SAA HB111-1998 ’The Domestic Kitchen Handbook’. Appendix B, page 90, of SAA HB111-1998 ’The Domestic Kitchen Handbook’. 20 www.ikea.com/ms/sv_SE 18 19. 27.

(30) In North America the cooktops come in 3 in increments: 24, 27, 30 and 36 in wide. That is 609.6, 685.8, 762 and 914.4 mm. 21 It seems like the 762 and 914.4 mm are the most used ones, apparently the Americans want bigger cooktops. In order to get one measurement to use in this project, the European and Australian markets were prioritised. The resulting product can be adjusted for the American market if needed.. 3.2.8 Benchmarking As written in 2.1.1, benchmarking can be done in different levels of intensity. To receive relevant information, but not spend too much time on the benchmarking, a benchmarking suitable for this project was done. It was structured and completed thoroughly according to the steps in 2.1.2 Teardown process, but some steps were not done completely. All of the components, for instance, were not measured and evaluated by cost and Bills of Material were not put together, since definitions of such things were not outcomes of the project. Distribution and installation were not considered a focus area either, so the installation was graded superficially based on a subjective overall impression. Along with the steps described in 2.1.3 Benchmarking approach, the evaluation of cooktops from Electrolux and competitors were conducted. Objects for comparison were chosen unstructured and subjectively, based on selling price, appearance and by talking to retailers and Electrolux staff about high quality, top of the range cooktops. However, as a result from expense restrictions, Electrolux did not approve of the orders for cooktops from competing brands and the only cooktops which have been evaluated are Miele KM 543 and Westinghouse PHL 768U. One other Electrolux cooktop has been evaluated as well, and it is included in the benchmark results, however, since it is not equipped with a touch control panel comparisons are not to be done. The cooktop was taken apart and examined for interest and knowledge purposes only. The three evaluated cooktops, and their results, can be seen in a benchmark form, in Appendix 2. Benchmark form. 3.2.8.1 The form The steps in 2.1.3 Benchmarking approach acted as guides for making a benchmark form as complete as possible, although every step was not carried out. The characteristics of the compared cooktops were divided into subgroups and measured in the benchmark form, see Appendix 3. Benchmark form – one cooktop. In this form both objective and subjective comparisons were made. The characteristics were measured, graded and commented in the form. Each subgroup also has two sections called “pros” and “cons” where other comments were made. Grades were given on a five increment scale: 1 = very bad 2 = bad 3 = satisfying 4 = good 5 = very good. 21. www.dacor.com, www.jennair.com, www.geappliances.com. 28.

(31) 3.2.8.2 Benchmarking results Some of the subjective characteristics were also evaluated through a user study, see 3.2.9 User test. In the results of the benchmarking, the grades of these characteristics are the mean value of all grades given. Quantified characteristics, such as height, weight, etc, are not graded. In the Appendix 4. Explanation of benchmark form, is an explanation of how the characteristics are evaluated. In line with 2.1.4 Setting product specification, the information gathered in the benchmarking process was put into the product specification which was formed in 3.2.7.1 Product specification. The following could also be seen: . The packaging Electrolux uses today is of enough high quality compared to the others’ packaging. The bottom plate can be designed and used in many different ways, but which way that is the best is hard to say. No major differences were found in how the cooktops were to be installed. Miele provided the best instruction for installation. The timer settings were graded very badly for all of the cooktops equipped with timer function. The Miele cooktop shows the temperature setting the best. The Miele cooktop has the best appearance and its interface is the most language tolerant of them all. The Westinghouse cooktop has got better sized and shaped keys than the others. The infrared (IR) touch control system is graded very bad for all cooktops equipped with it. The Westinghouse cooktop is easier to clean than the others, based on its lack of trim. The elements were from different suppliers but did not differ that much in offered wattage o size. They all had almost the same cool down time, but different ranges for the residual heat indication. Some had an indication in three steps, but it seemed unnecessary for the indication to be that detailed since the temperature above the lowest was far too hot for touching the element.. 3.2.9 User test The user test was conducted to let random users grade how good the cooktop’s different features are. The users were picked from Electrolux and represent different ages and genders. Each cooktop was evaluated by three persons. The form can be seen in Appendix 5. User test. The results from the user test is shown in Appendix 6 User test – results. To get the most out of the test, it was performed in the same manner with every test person and in a short period of time. The test person, TP, only performed the test at one cooktop to be able to do it with an open and clear mind, not influenced by new knowledge about for example touch control systems. 3.2.9.1. Evaluated features. Forces 29.

(32) . Sensitivity in control panel. Signals. . Hot zone warning Residual heat indication Timer indication On/off indication Heat zone adjustment indication Temperature indication Indication of element layout when not in use Indication of element layout when in use Color of lights Control panel graphics Color of graphics Information about program settings Information about faults. Safety. . Child-safety. Ergonomics. . Easy to understand control panel Size of keys Good grip surface. Functions . Turn on/off Heat adjustment Stabilize pan and contents Zone size variation Zone shape variation Time setting Time setting for specific cooking zone Programmed cooking. Style . Interface Control panel Top of the range appearance Quality-look Experienced safety Expensive looking Originality. 3.2.9.2 Set up The five different cooktops are fully installed and are placed beside each other. One medium sized pan is used. Zone number 1 is the largest circular one normally lower left (LL) and zone number 2 is the lower right (LR).. 30.

(33) 3.2.9.3. Test steps. 1. TP is welcomed and introduced to the cooktops, in particular the one he/she is going to evaluate. 2. TP is given the following tasks to perform at one of the cooktops: a. Turn the cooktop on. b. Put on zone number 1 to max heat. c. Turn on the biggest element. d. Set a time, of 3 min and 30 sec, for the whole cooktop. e. Turn zone number 2 on to medium heat. f. Set a time, of 3 min and 30 sec, on that zone. g. Put the child lock on. h. Set a program on medium heat in 3 min, after max heat up, on zone number 1. i. Turn the cooktop off. 3. TP is to answer the following: See the form. a. How understandable, and easy to use, is the control panel? b. What do you think of the sizes of the keys? c. Do you think that the surface gives a good grip/nice friction? d. What do you think of the sensitivity in the control panel? e. What do you think of the interface? f. How would you describe the cooktop’s quality expression? g. How safe does it feel to use the cooktop? h. Evaluate the signals mentioned. i. Who do you believe is the customer? Please describe him/her.. 3.3 Concept generation A couple of different methods for creating ideas and concepts have been carried out, for instance brainstorming, formulating a concept combination table and more. Many informal association sessions has been helpful as well. The use of more than a few methods ensure more variation among the resulting ideas.. 3.3.1 Brainstorming In individual brainstorming the participants think individually on a range of design issues and then discuss the resulting ideas with each other. This leads to new ideas and inspiration. This, and also a group session were performed where the participants spoke out loud creating a substantial variety of design ideas.. 3.3.2 Concept combination table In 3.2.5 Sub problems, the different areas of development were specified and by considering these in a concept combination table, a structured collection of ideas was put together. It can be seen in Figure 12 and Figure 13. These ideas have been combined to create new ideas and concepts.. 31.

(34) Figure 12. The nine sheet of ideas.. Figure 13. One sheet of A3-paper.. Since a lot of the sub problems are dependent of each other they can not be considered only one at a time. They can however, be divided into two main areas, the cooktop shape and interface layout. There are of course connections between these areas, but the interface layout may vary quite independently from the overall cooktop shape. 3.3.2.1 Cooktop shape To create a cooktop with a differentiating design and style, the shape of the cooktop, number of and placement of elements and placement and layout of the control panel was carefully considered. 32.

(35) 3.3.2.2 Interface layout When designing the cooktop’s control panel and interface, several aspects were taken into consideration; where should the control panel be placed? What type of keys should be used? How should adjustments be made? What kind of adjustments should be possible to make? What should different symbols look like? What information should be shown on the cooktop? How should changes in the settings be displayed? A good control panel layout makes the cooktop intuitive and fault proof to use. Many companies have their user manuals on internet and to get an insight in how a cooktop’s control panel looks and works, some of these were read.. 3.3.3 Cooktop shape concepts A lot of sketching and brainstorming created a large number of cooktop concepts, but as the cooktop needed to have a top of the range appearance the style in the sketches all share the same ambition. They are simple, neat, elegant and interesting with clean beautiful lines. The best ones were the ‘glass in front’, ‘glass on sides’, ‘glass trim’ and ‘wide’ as are described in following sections. The clear glass is further described in 2.3 Ceramic glass. 3.3.3.1 Glass in front A close to square cooktop with smooth brownish black glass is equipped with a piece of clear glass in front, see Figure 14.. Figure 14. Glass in front.. The front glass lies in line with the workbench’s longest side and this gives the cooktop a straight and nice look, as though it fits well on the surface. The clear glass lifts the appearance and it looks clean. The control panel is situated on and underneath the clear glass and red and white light shines through beautifully. It can be made out of slides positioned horizontally, see Figure 15, with a movement pulling to the right.. 33.

(36) Figure 15. Possible control panel.. 3.3.3.2 Glass on sides This cooktop has got the same black glass as the previous concept but two pieces of clear glass is added. On the left is a thin piece placed and on the right there is a wider piece of glass which is the control panel as well. See Figure 16.. Figure 16. Glass on sides.. This asymmetric design may draw attention to the cooktop in the kitchen and the placement of the control panel is perfectly situated on the right for right handed users. This help keep the children away from making adjustments of the temperature and the like. The control panel can in this concept consist of vertically placed slides, which would lead to a nice pulling slide movement and look good, see Figure 17.. 34.

(37) Figure 17. Possible control panel.. 3.3.3.3 Glass trim A cooktop surrounded by a trim can be marketed as a cooktop which can hold spilled liquid. The trim would also make the cooktop stand out and draw attention to the interior, see Figure 18.. Figure 18. Glass trim.. The control panel could be placed in the trim or in the back glass. 3.3.3.4 Wide This cooktop is wider than the others and the elements are to be placed next to each other in a row. A new look may come from this and be interesting enough to attract buyers. A stainless. 35.

(38) steel trim is situated in the front and has a cut out area where the black glass comes through. See Figure 19.. Figure 19. Wide.. The placement of the control panel in this cut out area, in the glass, protects it from the cooking and pots and pans. The infrared touch control system used today, reacts when pots are moved too close to the controls.. 3.3.4 Element layout concepts From the research made, the opinion of not being completely satisfied regarding the cooking zones emerged. They are too small and placed too close together so when using a big pan on one zone at front it normally covers parts of the rear elements, in the ordinary four element cooktops. The number of elements were also questioned, why have four elements if you do not cook on all of them? Or would the target user group like to have five elements to be able to impress? A number of element layouts were drawn up based on the conception that the cooktop needs to have large elements that fit the sizes of commonly used pots and pans. Series of pots have been investigated for this purpose and unstructured interviews have been made with friends and family to find out what sizes they use when cooking and elements were picked from the suppliers EGO, EIKA and Ceramaspeed. In 2.2 Element technology is information about how an element works. The placement of the elements are based on the idea of having element sizes for pots that need more surveillance while cooking, in front, and sizes for pots used for cooking in less need of surveillance in the back. Five of the best layouts are shown in Figure 20-24. and here elements from Ceramaspeed are used, the model Magma. Ceramaspeed is Electrolux’s supplier today.. 36.

(39) Figure 20. Element layout A1. Figure 21. Element layout A2.. Figure 23. Element layout A4.. Figure 24. Element layout A5.. Figure 22. Element layout A3.. 3.3.5 Interface concepts The goal for this project is to make a cooktop that feels unique and at the same time is so easy to use that a manual is not needed. Just by trying out the buttons the user should be able to make out how it works. Rules of how a user interpret certain things in an interface is described in 2.5 Interface & symbols. A consumer who feels secure and confident while using a product also feels happy with it. If a product provides too many choices the customer might not know how to handle it which leads to insecurity and a discontent with the product. Therefore multiple layers and multifunctional buttons should not be used. 22 Also, most retailers have their test-cooktops connected to power so that the customer actually can try the interface while in the store. This makes a good interface even more important as a sales argument. 3.3.5.1 Features Information about different features of cooktops already available on the market was found by visiting retailers and looking on the Internet. Most of the features and functions found in these cooktops are represented in the control panel as adjustment sensors, symbols, light and/or sound indications. Table 2 was made both to get an overview of different features and functions and also to get an idea about what should be considered when designing the interface. A = adjustment sensor required S = graphic symbol required I = light and/or sound indication required.. 22. Christine Gall, Electrolux.. 37.

(40) Table 2. Cooktop features. Feature. A. S. I. 1. Cooking sensor. 2. Cooking programs. x. x. x. 3. Time alarm. x. x. x. 4 5 6. Element switch-off Fault information On/Off key. x. x. x. x. x x x. 7. Over heating protection. 8 9. Panel lock (Child-lock) Pan sensor. x x. x x. x x. 10. Pan size sensor. x. x. x. 11. Quick heat-up. x. x. x. 12. Residual heat indication. 13. Setting adjustment. x. 14. Low simmer. x. 15. Spill protection. 16. Safety switch-off. 17 18. Zone shape variation Zone size variation. x. x. x. x. x x. x x. x x. x x. Description Measures temperature to sense when specific temp. is reached. (Special pans and pots needed) Preset programs. Made by manufacturer. One for rice, etc. Manual programming. The user makes programs with different temperatures for different times. A timer only functioning as an alarm, that is, does not turn cooktop of. Set a time for a separate element. Element turns off. Indicates that something is wrong/what is wrong Turns cooktop on or off. Senses the temperature in the element and switches it off if it reaches overheating temperature. Locks panel Cooktop feels presence of pan and turns on. Cooktop feels size of pan and adjusts number of cooking zones to use. Heat is delivered with maximum effect to a zone set for a lower temperature. This is to make it heat up faster. If, for example a heat setting at 50% of the maximum is made an effect of 100% will be delivered to the zone for a preset time. A lower heat setting means a shorter time of maximum effect delivery to that zone. Can be optional to use from time to time by adding a ‘quick heat-up’- on/off key. After zone is turned off. Might be in different steps up to 3. Can be used to keep food warm. Possibility to adjust light and sound output. Cooking zone can be kept at low temp. Sometimes this is a special zone, separate from other heating areas Warning is given if there is liquid on control panel. Turns off if controls not used. For example, element set on high heat turns off after~1h, element set on low heat after ~10 h. To fit oval pots and pans Different sizes of pots.. Through brainstorming a new feature was discussed, a weighing scale. It could either be mounted in a trim or directly under the same glass as the elements. This feature was thought to appeal to health conscious people living a fast life. By including it in the cooktop it would make it easier for example to cook pasta; when the water is boiling simply move the hot pot to the weighing area, reset to zero and then add the exact right amount of pasta. This idea was discarded though in a quite early stage after examining the technique needed. It would be very hard and expensive to manufacture in order to work in a satisfying way. The need for such a function can also be discussed. 3.3.5.2 Control panel One of the biggest reasons for buying a ceramic cooktop is that it is easy to clean. Having knobs, described in 2.4.2 Knobs, on the surface takes away the smooth, flush appearance and that is why only touch controls are being considered in the interface development. See 2.4.1 Touch control. Another argument why to choose touch controls is that you do not have to make holes by drilling in the glass.. 38.

(41) The interesting magnetic control technique, explained in 2.4.3 Magnetic point and twist control, is modern and of high quality, although, this is not a new idea since competing cooktops already are using this technique, and it is not considered in this project. The producers that make IR-controls only have a few models of circuit boards, and making special designs of these are quite expensive. Therefore further development of the interface was made with a capacitive touch control in mind. See 2.4.1.2 Capacitance for information about the technique. After discussions with a supplier of capacitive controls it was found that the price for this technique will not be much more expensive than the IR-controls that are used today. Also, capacitive controls are much more reliable and easier to use. This will give the cooktop’s interface a better quality expression, and since the infrared gives a fairly bad quality impression, this cooktop will surely stand out in the retailer’s display. The only problem with capacitive controls is that they can react from the water film created by wiping over the control panel surface with a wet cloth. This is avoided by including a “cleaninglock”, locking all keys, in the cooktop. In addition to 2.4.1.2 Capacitance, the capacitance touch control consists of a matrix lying under the ceramic glass surface 23 . Adjustments can be made by touch, double tap or sliding the finger in whatever path. Shape and layout of adjustment areas are restricted more by the size of a human finger than the technique required. The possibility to change the colours of lights is mainly limited to what colours the glass lets through. Sounds can also be varied a lot. This technique opens a wide range of possibilities when making the interface. Cables and connection-harnesses are not limiting for the layout, since it is easy to adjust the length of cables and have therefore not been taken into consideration for the rest of the development work. After deciding features to include and what technique to use two control panel concepts were developed. The difference in the concepts lies in the number of keys, that is if it has few function keys or multiple function keys. A sketch is made to both concepts. These sketches are only a draft to show the principle of each concept and does not show the final design or layout of the keys and indications. 3.3.5.3 Interface concept 1 – Few function keys In this concept all elements have their own temperature adjustment slide and also their own zone size adjuster. Element timer is adjusted by a shared slide, but time remaining is indicated next to each element at the control panel. The time alarm has its own indicator. The following keys are used: . 23. Key 1 Key 2* Key 3* Key 4* Key 5 Key 6*. Cooktop on/off + child-lock Element on/off + element selector Temperature adjuster Zone adjuster Timer adjuster Quick heat-up. Andrew J Palmer, Invensys Controls.. 39.

(42) The “*” means that there is one key for each element. To the keys there are indications that give feedback to the user. In Table 3, all these indications, labelled A-K, can be seen. The table also tells what kind of indication there will be: graphic, light and/or sound and which key that is connected to the indication. In Figure 25 both keys (1-6) and indicators (A-K) are marked.. Figure 25. Concept 1, few function keys.. So, how does this control panel work? In the following sections the use and the function of the cooktop is described. The numbers refers to the keys and letters within ( ) refers to the indications listed in Table 3. Table 3. Indicators included in few function keys- concept Nr. Indication. A B C D E F G H I J. Cooktop on/off Element on/off (control panel) Element on/off (at element) Zones in use Temperature Time alarm Element switch-off Residual heat Fault information Quick heat-up. Graphic. Light. Sound. x x x x x x x. x. X. x. x x x x x x x x. X. X. Affected by Key 1 Key 2 Key 2 Key 4 Key 3 Key 5 Key 2 + 5 Key 6. Cooktop on/off + child-lock. The cooktop is started by sliding key 1 upwards. A sound indicates that the cooktop is turned on and also a light is lit as long as the cooktop is switched on (A).To turn the cooktop off slide key 1 upwards again. By making key 1 as a slide it also holds the function of a child-lock since it requires a specific motion in a specific direction to react.. Element use. Key 2 is touched and then key 3, 4 and 7 are used to make the adjustments. An indication (B) by key 2 shows that the element is selected. Adjustments need to be made within 10 seconds after pressing key 2. If not, key 2 must be touched again before adjustments can be made. 40.

(43) At key 4 is decided how many zones that will be used and light indicates the amount (D). At key 3 heat is adjusted and shown at the same time on a scale (E). If quick heat-up is wanted, finger touches key 7 and a light indicates that the feature is chosen (K). To turn off the element drag the temperature to zero. When an element is in use the red light shows through the ceramic glass. When the element is switched of graphics indicates the element layout.. Residual heat. After using the cooktop residual heat indicators show how the elements gradually cool down. First three, then two and finally only one indicator is lit.. Time alarm. The timer can be used either as a time alarm or to switch off elements. If used as a time alarm, touch key 5 and make adjustments by sliding up or down. The time remaining is shown with both minutes and seconds on a separate display (F) and beeps with increasing volume when time is up. To adjust the time alarm after it is set, double-click key 5 (the numbers on the display starts blinking) and then make adjustments. To stop the alarm before time is up; push finger down the slide of key 5 till the time is “00.00”. After two seconds the display turns off.. Element switch-off. If used to switch off elements, select the element by touching key 2 and then adjust the time at key 5. The time remaining is shown with both minutes and seconds in a display (G) next to key 2. Five seconds before the time is up two beeps are heard and the display next to the element starts blinking to indicate that the element will shut down. To adjust the time after it is set, touch key 2 and then double-click key 5 (the numbers on the display starts blinking) and then make adjustments. To stop the alarm before time is up; select the element by pushing key 2, and then push finger down the slide of key 5 till the time is “00.00”. After two seconds the display turns off. 3.3.5.4 Interface concept 2 – Multi function keys In this concept the elements share temperature and timer adjuster. By first choosing zone and then the action, settings are adjusted. Temperature, quick heat-up and timer are all adjusted by one key which is the same for all elements. To make adjustments for a specific element, choose the element and then make adjustments wanted. Keys used: . Key 1 Key 2* Key 3 Key 4* Key 5 Key 6. Cooktop on/off + child-lock Element on/off + element selector Temperature adjuster Zone adjuster Timer adjuster Quick heat-up. The “*” means that there is one key for each element. Table 4 shows the indications and how they are connected to the keys. In Figure 26 both keys (1-6) and indicators (A-K) are marked.. 41.

(44) Figure 26. Concept 2, multi function keys.. In the following sections the use and the function of the cooktop is described. The numbers refers to the keys and letters within ( ) refers to the indications listed in Table 4. Table 4. Indicators included in multiple function keys – concept. Nr. Indication. A B C D E F G H I J. Cooktop on/off Element on/off (control panel) Element on/off (at element) Zones in use Temperature Timer Residual heat Fault information Quick heat-up Switch-off function activated. Graphic. Light. Sound. x x x x x x. x x x x x x x x x. X. x. X X. Affected by Key 1 Key 2 Key 2 Key 4 Key 2+3 Key 5 / 2+5 Key 6. Cooktop on/off + child-lock. Works in the same way as concept 1.. Element use. Key 2 is touched (B) to turn the element on. To select how many zones to use key 4 is touched. Temperature is adjusted by first selecting the element (key 2) and then sliding along key 3. Temperature for each element is shown next to key 2 (E). Quick heat-up, key 7, is chosen next to the common temperature slide and is indicated next to each element (J). Which element that is being adjusted for the moment is shown by an indication (K) next to the temperature display (E). When an element is in use the red light shows through the ceramic glass. When the element is switched of graphics indicates the element layout. 42.

(45) Residual heat. Works in the same way as concept 1.. Time alarm. Works in the same way as concept 1.. Element switch-off. If timer is used to switch of elements, select the element by touching key 2 and then adjust the time at key 5. To start countdown press key 2 again. The time remaining is shown with both minutes and seconds in a common display (F) next to key 2. Indications (J) next to key 2 shows which elements that are timed. To make adjustments to an element timer touch key 2 and then key 5. Alternate the display between different elements by touching key 5. Five seconds before the time is up two beeps are heard and the display next to the element starts blinking to indicate that the element will shut down. To adjust the element timer after it is set, double-touch key 5 (all of the timer indications next to the element symbols starts blinking), then touch key 2 of the intended element (all other elements stop blinking) and finally make adjustments at key 5. To stop the alarm before time is up, select the element as above, push finger down the slide of key 5 till the time is “00.00”. After two seconds the display turns off.. 3.4 Concept selection To find the best concept for a cooktop, the concepts for the overall shape, the element layout and the control panel must be considered one at a time, but, how they would interact with each other must also be kept in mind.. 3.4.1 Criteria weighting A weighting was carried out in order to determine what criteria are the most important. The matrixes and the rating can be seen in Appendix 7. Criteria weighting and an example of such a matrix in Table 5.. 43.

(46) Cheap packaging method. Environmental friendly packaging. Environmental friendly packaging method. Transport friendly shape. 1. Transport and packaging. Package should give impression of quality. Table 5. Part of the criteria weighting matrix.. 1 2 2 2. 0 1 0 0. 0 2 1 1. 0 2 1 1. 1 1 1 1. 2 8 5 5. 8% 32% 20% 20%. 1. 1. 1. 1. 1. 5. 20%. 25. 100%. Package should give impression of quality Cheap packaging method Environmental friendly packaging Environmental friendly packaging method Transport friendly shape. 0 = Less important 1 = Just as important 2 = More important The rating is summarized and the percentage of importance is received. To be able to compare criteria in different areas, where transport and packaging is one example of such area, an comparing matrix is conducted. See Table 6. Piece of the total criteria weighting matrix.Table 6. Table 6. Piece of the total criteria weighting matrix.. The five most important criteria were found to be: . Child-safe Ergonomic control panel adjustments Good alarm sound. 44.

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