In 1977, when I was two, Ken Knowlton invented a system for superimposing images over fingers on keys using a TV-screen, a glass and a mirror.
You may find discription of a display keyboard in IBM's 1978 paper: Jones, "Programmable Keytop Employing Electrochromic Display", IBM Technical Disclosure Bulletin, vol. 21, No. 4, Sep. 1978, pp. 1671-1672.
See also USPTO patents granted every couple of years:
4,078,257 (filed 1976)
4,897,651 (filed 1986)
5,818,361 (filed 1996)
7,301,532 (filed 2004)
20080001787 (filed 2007, aka Apple's patent)
And so on. Almost in any industrialized country's patent office you may find similar inventions. There are two or three of them in Russia as well. We've tried to contact inventors of one of the the Russian patents (to use their patent number on labels) only to discover 'greedy soviet engineer syndrome' that makes people ask for one million dollars downpayment and a royalty for the rest of their life.
Finally we've settled with our own patent procedure that will protect our engineering solution.
Idea of putting displays into keys appeared to be common in heavy machinery industry, as well as in hi-end telephone stations.
I'm paranoid enough not to publish projects whose main attraction is just an idea. So when in 2005 I've decided to finally put Optimus concept renders online I really believed I'm the first to come up with the idea. Pretty soon I've learned about all the patents and prior art, but it was too late: I've decided to make it real (and it is real now).
When we were in the middle of the production, I've learned about the German inventor named Reinhard Engstler who was inspired by the IBM paper and designed the LCD-keys keyboard in 1984. Keyboard was on sale under different no-name brands. For example, last summer one Russian from Germany sent me a model branded simply 'theBoard' as a gift. Here is is side by side with Optimus Maximus:
It turned out that this keyboard (under the 'HOHE Electronics' and 'K-E-T TheBoard' brands) was on sale even in USSR. Here's an ad from the 'Business contact' magazine (#3, 1990).
In a month after Optimus concept was revealed there appeared two other companies with no background claiming they were doing the same stuff - display keyboards.
On of them was called iKeyTypePro. Guy behind it, named Bruce Grand, while being based in Moscow (what a coincidence!) was accusing me of using his idea (see iKeyTypePro LCD-based multi-language keyboard, Aug 2005).
Their website showed two images: a very bad render and a very bad prototype.
Their website, ikeyinfinity.com is no more. Company who claimed they have everything ready for production while I had only nice renders, has disappeared.
Another company that got noticed by the media within weeks after Optimus concept was published is United Keys.
United Keys never showed any piece of circuitry, only Photoshopped images. Initially it was the '205pro' keyboard:
Then they abandoned this image for a more glossy one:
Experienced keyboard users may note similarity with the Microsoft Internet Keyboard:
You may also want to read a very interesting piece of gossip published yesterday on Medisonscam: United Keys & Valdi's imaginary keyboard. What got my attention is a quote from United Keys' Valdi Ivancic who is accusing me of using his idea and a 'two million Swedish crowns scam' (read original in Swedish).
So, what's the morale of this story?
Just as LCD Keys company website is making a point (I believe these to be the words of the German engineer Reinhard Engstler): "it proved to be more difficult to come up workable switch design that integrated an LCD in a key top and make it work. Many tried and failed."
We have absolutely unique device with full-color displays - already mass produced. Every other claim should at least show the process (as we did), or the result.
Patent numbers don't mean almost anything, because the easiest part of making a display keyboard is to bypass any existing patent.