Browse Prior Art Database

Plate Glass Keyboard

IP.com Disclosure Number: IPCOM000034864D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 3 page(s) / 64K

Publishing Venue

IBM

Related People

Glass, DW: AUTHOR [+4]

Abstract

Disclosed is a keyboard which can be activated through a barrier, such as a plate glass window, by the user's finger or other mechanism in order to control a computing mechanism located behind the window. The concept extends to other input capabilities through a barrier, such as a bar code reader or symbol recognizer. Reflected light is used as the input. This allows the keyboard to be behind a glass plate. (Image Omitted) Fig. 1 shows a flat keyboard 1 that uses reflected light of a known frequency range as input. The key locations and nomenclature are similar to standard keyboards. This flat keyboard sits against a glass plate 2 which is encased in a protective cover 3. This cover keeps the computer unit and user environmentally separated. Fig. 2 shows a detail of a particular key.

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Plate Glass Keyboard

Disclosed is a keyboard which can be activated through a barrier, such as a plate glass window, by the user's finger or other mechanism in order to control a computing mechanism located behind the window. The concept extends to other input capabilities through a barrier, such as a bar code reader or symbol recognizer. Reflected light is used as the input. This allows the keyboard to be behind a glass plate.

(Image Omitted)

Fig. 1 shows a flat keyboard 1 that uses reflected light of a known frequency range as input. The key locations and nomenclature are similar to standard keyboards. This flat keyboard sits against a glass plate 2 which is encased in a protective cover 3. This cover keeps the computer unit and user environmentally separated. Fig. 2 shows a detail of a particular key. Each key on the keyboard is similar in operation. The keytop 4 is stationary and has appropriate nomenclature 5 printed on the face. The remainder of the keytop 6 is transparent. The key frame 7 holds an LED (light-emitting diode) 8 in the LED cavity 9 and a PTX (photodetecting transistor) 10 in the PTX cavity 11. The frame does not allow light passage except directly above the LED and directly above the PTX. A divider 12 in the frame keeps light from directly going from the LED to the PTX.

A front cover 13 and back cover 14 keep light from entering or exiting the front or back of the key unit. Light is reflected from a user's finger which is pressed against the glass. The thickness of the glass is accounted for in the design of the angle. The LED and PTX operate at a given infrared frequency that is not otherwise present in the room. Stray reflection of the infrared light above the glass plate is not sufficient to trigger the PTX. A lens is placed on the LED and on the PTX, and the LED and PTX are positioned such that the path of the reflected light maximizes the PTX triggering. Note that a pin photodiode, such as the Texas Instruments TIL413, may be used. This particular photodiode includes a built-in infrared filter that substantially improves performance in the presence of incandescent and fluorescent indoor lighting. To enhance feedback to the user, audio beeps may be provided with each keypress. A small speaker mounted on...