I used to design the units in airliner armrests that controls entertainment, reading light, etc. It's a very demanding application for membrane or tactile dome keys but they are pretty durable.
The tomato comment is funny... one requirement for the membrane keypads was stain resistance. The worst substance was tomato sauce...we never found a material that was 100% impervious to tomato sauce stains and still able to meet other requirements.
We have two table-top clock radios which are at least 25 years old. While each one sports a different "manufacturer" nameplate (GE, EMERSON), both are almost identical design, so it's obvious that they originated from the same Asian factory. After years of use, the TIME/ALARM SET button on the top became inoperative. Opening up the cases, there is a cheap-quality p.c. board w/ traces, and small spring-loaded buttons poking through the case. This p.c. board is connected to the main ckt. board w/ discrete wires. I removed the board, and carefully brushed off the contacts on the circuit board AND the mating contact on the buttons, reassembled both radios, and both are back to original condition. A typical press onto the button, and the time LEDs advance properly. I guess the circuit current is so low that the miniscule oxidation on the surface of the contacts prevented a reliable path of signal.
I hope these radios outlast me, since I don't see anything even remotely like these two simple devices in the stores anymore. Our only regret is that they don't feature dual-set capability. Nowadays, a clock radio at bedside is a "docking station" for the smartphone...... simple solutions have evolved into sophisticated, unneeded options!!!!
Where's the horse & buggy when I need one????? All I wanna do is go to HOME DEPOT for a box of nails!!!!
It amazes me how some manufacturers get away with poor designs. At Danielson (UK) Ltd, we have carried out extensive research and tests to overcome the problem of silver migration and regularly carry out environmental and life tests to prove the adequacy of designs.
My company manufactures appliances which are equipped with membrane keypads. OK, you can all stop throwing tomatoes at me. Membrane keypads are, in fact, extremely reliable, good for well over 100K operations. They provide the designer with a great deal of flexibility of design, since the entire functionality of the product can be defined simply by fitting different membranes to the same hardware - add or remove a few buttons, change the graphics, it's just 1000$ tooling to change from one product to the next. The hardware can even "read" he keypad type and figure out which model it is.
Membrane keypads usually fail at the time they are installed in the product. During assembly the ribbon can be over-flexed, causing cracking, or the membrane itself could be flexed, which can cause the metal dome to shift (if your membrane has plastic domes, you've bought an inferior product). They won't be going away any time soon, and you won't see the return of mechanical buttons.
One product line I had was for agricultural appliances and we went through several membrane manufacturers before settling on Bergquist. Your mileage may differ, but they made the best switch for what we needed to do. They were a top-dollar vendor and worth every penny. Prior to that we had switches corroding, delaminating, collapsing, and plenty of silver migration. The returns were so bad that we promised one customer that we would replace every membrane switch in the field with a Bergquist part even if the original was still good.
The next product I designed was tactile switches with a graphic overlay, but even then I still used Bergquist for the overlay.
Hey, Tekochip, I don't like membrane buttons either. All you need is to have one membrane begin to crack and it ruins your taste for thses buttons. I've also experienced the trouble when you have to press extremely hard to make the button work.
That's certainly a bad membrane switch and I'm sure Kitchen Aid will replace it.
I do rather agree that discrete switches are better than membranes, just because it's so tough to build a good membrane, especially for a dishwasher. There are some great vendors out there, like Bergquist, but then there are others that will fine tune their process at your expense. Given the choice, I always purchase a device with tact switches rather than membranes.
I've complained about membrane keys before, and I'll do it again here. They are hard to use, and has been discussed before, become harder to press as the mechanism degrades over time. The problem with the author's advice not to buy them is that they're everywhere. I wish appliance manufacturers gave them as an option, not as standard equipment.
I see Oliver's point, though. I have a different brand of dishwasher whose membrane keyboard had to be replaced while still under warranty. For some reason, the previously quiet dishwasher is now irritatingly noisy. Some seal must have been compromised in the repair process.
What should be the perception of a product’s real-world performance with regard to the published spec sheet? While it is easy to assume that the product will operate according to spec, what variables should be considered, and is that a designer obligation or a customer responsibility? Or both?
Biomimicry has already found its way into the development of robots and new materials, with researchers studying animals and nature to come up with new innovations. Now thanks to researchers in Boston, biomimicry could even inform the future of electrical networks for next-generation displays.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.