Design Solutions
Programme 2: Electronics

Aims

This programme aims to introduce students to the following:

To demonstrate the various stages involved in developing a new product to complement and update a well-known product type
To show various methods of modelling to explore design ideas - block systems, diagrams and physical block form models, 3D computer-aided design (CAD), CAD simulation electronic systems, working prototypes
To emphasise the importance of testing, debugging, modifying and testing
To show how various experts and disciplines work together in product development, specifically product designers and electronic engineers
To illustrate the design processes involved in the configuration and integration of electronics and the product casings

Outline

This programme follows a team of designers who are designing a new instant digital camera.

0:00 – Polaroid is a company well know for instant photos. The UK office is in Scotland where products are designed and assembled for distribution worldwide. Grant King, European director of products for Polaroid, explains that they are keen to have an all-in-one digital camera and printer for use by small companies worldwide. He describes it as a passport photo booth in a box. The Polaroid corporate marketing team asked for a new design to meet with this brief. The initial specification is for a camera which produces instant excellent quality images, is portable, light enough to be hand held and attach to a tripod, and easy to use with the minimum training.

1:00 – The electronic engineer, Scott Aroll, has the responsibility of overseeing the design and development of the new product. He starts with a list of functional requirements in order to get an understanding of the various components required for the system in general. He acknowledges that ideally everything would be on one printed circuit board (PCB), but that that would not be good for the shape and form of the product the user interfaces with. He has to work out how to split the various parts up and negotiate with the industrial designers to come up with a cost-effective solution.

2:00 – The Product Design Engineer (PDE), Dan Hampshire, starts by thinking about how the main parts of the camera, the lens and the printer, can go together. He explores the various possible configurations using freehand quick sketches. He experiments with a range of possibilities and notes down all his ideas.

3:00 – He then moves on to physical 3D modelling using foam board. The 'rough and ready' model allows him to hold, test and judge the concept more fully. He asks for feedback from others in response to the handling of the concept mock-up model. Dan explains why he likes physical models and how they can assist in the design development.

5:00 – When he gets approval from Polaroid on his concept ideas, Dan prepares his design on the CAD system to develop technical details. The software shows intersections and this allows him to check for clashes between surfaces and to modify and ensure the various components, casings, etc will fit together. The electronic engineer discusses details with the product design engineer to ensure that the circuit boards hold sufficient space for the components and that the PCB will fit into the casing. In this way problems are solved in negotiation and an accurate resolution can be arrived at.

7:00 – Scott uses block diagrams, as a model of the system and the function until he is satisfied that it will work and then the design development progresses on to CAD.

8:00 – Electronic engineer, Jonathan Kelly, uses CAD to design a schematic layout of the PCB - the 'schematic capture'. He works with the boundaries and sizes of the mechanical housing prepared by Dan, and positions the components in a layout that takes these restrictions into considerations to make the required PCB to size.

9:00 – The problems of interference and electrical noise from the charged couple device (CCD) and the need for care in the placing of support devices, are described.

9:30 – A working engineering prototype is produced for testing. Errors should be identified at this stage rather than further down the line when they would incur far greater expense. This is known as the 'debugging' phase.

10:00 – The digital camera test image produced was corrupted. The source of the electrical interference has to be diagnosed and resolved. The additional components (resistors and capacitors) required to act as a filter, are added and retested.

12:00 – The finalised PCB design is sent as CAD files to an outside specialist company for production. The manufactured PCBs are sent back to the Polaroid factory for assembly and final production of the camera.

13:00 – Twelve months on from initial briefing, the camera is seen in use by a professional photographer who evaluates it and commends it on its portability, functionality and ease of use. Polaroid indicate that there has been positive feedback on their new line of instant cameras.

14:00 – End of programme.

Curriculum Relevance

Scotland: National Qualifications Technological Studies: Intermediate 2 and Applied Electronics: Higher

Outcome 1 and Outcome 2

The design of a circuit is explained in relation to the specification provided. The components and subsystems are explained. It illustrates the use of block diagrams to analyse the functions of the technological system and how this develops into a circuit diagram through software simulation; demonstrates the application of technological concepts in a user-friendly practical design solution. Exemplifies testing to verify the system, uses test equipment and simulation to identify how to rectify the problem identified with additional components on the existing circuit. The need for circuit protection and the concept of electrical noise and interference is central to the development of the circuit. Covers n-p-n transistors, opamps, etc. The relationship between the design of the circuitry and the physical housing of the product for the user is made explicit.

Craft and Design Intermediate 2 and Higher:
Designing for People and as Design Assignment stimulus.

The programme covers the general phases involved in the design process and the role of various design team members. It illustrates the use of a wide range of model types for design development from concept to final product. It shows the exploration of the various factors that influence design. It emphasises the importance of continual testing to identify problems at early stages of the designing processes and the need to get feedback and evaluate throughout the process. The importance of communication and verification of the ideas and work of both the electronic engineer and the product design engineer in order to arrive at a negotiated solution, which suits the requirements of the client, the users and the technical constraints, is made explicit.

England: National Curriculum KS4

Developing, planning and communicating ideas: a,b,e,f,g

Evaluating processes and products; a,b,c,d

General Curriculum relevance

This programme will allow teachers to exemplify aspects of designing and could support the teaching of electronic products and product design courses.

Background

This programme exemplifies the consultation between various disciplines involved in the different aspects of a product. The marketing and sales team are aware of what they could sell and the product research and development team are asked to design a product to meet the given specification. There are two main concurrent processes:

the configuration of the key components, aesthetics and ergonomics of the product (outside handling and interface) and the packaging of the internal circuitry
the circuit design.

Both processes use modelling and simulation to evaluate and review. Both designers require information from each other as they are designing. It is important that the two designs come together in terms of scale and compatibility. Problems arise and these have to be resolved in both electronics and housing areas. It is useful to compare the different ways in which CAD has been used in this example of product design engineering.

The programme describes some interesting design problems that illustrate the issues which arise when moving theory into application. The contextual setting provides interesting ways in which to cover these with the students. For example the cause of electrical interference, specifically from the charged coupled device (CCD) of the camera's light-sensitive screen of phototransistors, offer opportunities for a variety of tests in the classroom to ensure understanding of the problem described in the programme. It is useful to note that even companies such as Polaroid, which will have tested and retested the circuit many times on their CAD package, use physical testing in order to fine-tune their devices and PCBs. The computer simulation software rarely indicates subtleties of electrical noise, (see suggested activities).

It is interesting to note the shape of the PCBs. Most electrical products tend to be rectangular and are packed in flat boxes - CD and video players, computer motherboards. The design challenges come when the ergonomics of a product is not compatible with a box housing.

The company will have a range of standard components and many subsystems will exist, eg power supply, modular amplifiers. These standard components will be incorporated into the new product. This is know as 'leverage deign', eg 40% of the design effort is reused in new products to spread the development costs. This programme offers opportunities to discuss such commercial approaches.

Activities

Before viewing the programme

The students could discuss the range of disciplines they think are involved in the design of technological products that are common today. Discuss the general design process stages and factors that will have to be considered. Remind them of the importance a design and performance specification plays in the generating and development of design ideas.
Students should be reminded of the use of system diagrams, block diagrams, CAD, electronic PCB design to arrive at a solution that meets the requirements of function and performance.
Explain the terms electrical noise and interference - demonstrate by using an oscilloscope and signal generator. Switch the lights on and off to illustrate the bounce trace on screen. Place a capacitor over the circuit and repeat. View and discuss the trace. Discuss the reason a CCD may produce amplified interference noise as well as the required signal from the CCD capacitors.

After viewing the programme

Write out the initial specification, which lists the key features / factors that must be considered by the designers.
Discuss with the students the importance of careful planning of the circuit and the need to negotiate with the product designer regarding the physical size and configuration of the various components and PCB incorporated in a product. Encourage them to consider why it is important that testing identifies problems at early phases of the design development.
Discuss the advantages and disadvantages of physical models over computer simulations and 3D models. Build an n-p-n / flip-flop circuit and test for electrical interference with the oscilloscope, to compare with a computer-simulated circuit. (Select a transistor to exaggerate 'noise' and switch bounce.) Use the size and the frequency of the waves to inform the decision of the size of capacitor to filter the peak. Solder in and recheck. Compare this classroom process with that of Polaroid.
Research CCDs. Find out what they are and where else they are found (scanners, barcode readers, etc). Ask the students to explain why there is a problem of interference. Discuss the approach the electric engineer took to diagnose the problem with the circuit board and the purpose of the additional capacitors and resistors, ie examine the clues given by the lines on the test photo print out. When the test image is marred by evenly spaced lines of interference, it signals that there is a regular frequency of noise switching 'on and off' compared with uneven / random noise which would have been indicated by unevenly spaced lines in the test piece.

Links

This web page contains links to other websites that are neither controlled nor maintained by Channel 4 Television. Channel 4 Television is not responsible for the content of these sites and does not necessarily endorse the material on them.

For information on how digital cameras, including detail of CCDs, work check out http://electronics.howstuffworks.com/digital-camera.htm

Visit the Polaroid website to place the product in context of the product range: www.polaroid.com/index.jsp

Design Solutions Programme 2: Electronics