In May 1982, OTI advertised a design for (depending on which line of the advertisement you read) an “optical keyboard” or “optoelectronic keyboard”. To minimise power consumption, the LEDs are multiplex and only powered up on demand. N-key rollover was provided.
The diagram in the advertisement shows a sensing arrangement around two keys wide. It appears that there is a spring or buckling rubber sleeve under the keycap, and below the mounting plate is a shutter which interrupts the light beam. Since two keys as depicted could not exist side by side, one possibility is that the shutter spans the depth of the key, with the LED and photoreceptor assemblies being staggered front-to-back between keys.
The California Secretary of State business search website lists a corporation named solely “OTI” (entity number C1038245) registered in May 1981, a year before the advertisement was placed. The only records for this company span from the registration on the 3rd of March 1981 to “SI-COMPLETE” on the 31st of March 1982, and the company status is “FTB SUSPENDED”. As such, the business is seemingly not dissolved, but simply prohibited from trading pending resolution of regulatory matters. Californian business records are hopelessly vague, giving no written indication of when the suspension occurred, but the implication is that the company did not remain trading into 1983. Whether any such keyboards were ever produced, is presently a mystery. If they do exist, they are likely to have been made within the years of 1981–83.
- Optoelectronic keyboard advertisement, Computer Design, May 1982