Optical keyboard with common light transmission members

• US 4,417,824 A
• Filed: 03/29/1982
• Issued: 11/29/1983
• Est. Priority Date: 03/29/1982
• Status: Expired due to Fees

• Current Assignee: IBM Information Products Corp. (Ninestar Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Sublette, Jerry M., Paterson, Robert L.
• Primary Examiner(s): Burr, Edgar S.
• Assistant Examiner(s): Wiecking, David A.
• Application Number:
  US06/375,799
• Time in Patent Office: 610 Days
• Field of Search: 400/477, 400/479, 400/472, 178/17 C, 178/17 D, 235/145 R, 250/221, 250/578, 340/365 P, 350/96.1, 350/96.15, 350/96.16, 350/301
• US Class Current: 400/477
• CPC Class Codes: B41J 5/08 Character or syllable selected by means of keys or keyboards of the typewriter type
• CPC Class Codes: H03K 17/969 having a plurality of control members, e.g. keyboard

Abstract

A keyboard assembly (FIG. 1, 11) is constructed of first light transmission members (13) second light transmission members (15), a key actuation assembly (17) having a matrix of keybuttons (25), plural light source assembly (19) and plural sensor assembly (21). Each light source on assembly (19) is exclusively and sequentially energized causing its light to be transmitted through the first light transmission member (13) to be split up and deflected downwardly by the surfaces (43) and then rightwardly by the surfaces (45) to emanate through the surfaces (47) to enter the surfaces (49) of the second light transmission member. Actuation of a keybutton (25) causes its associated interrupter (29) to assume a light blocking position between the first light transmission member (13) and a second light transmission member (15). Light passing through the second light transmission member (15) to the sensor array indicates that none of the interrupters (29) have blocked the light path. This geometrical arrangement provides N key rollover detection with phantom key lockout and the light transmission members (13, 15) may be made of a single part or a single part for each row or column. Such parts provide common light transmission paths.

Claims

1. A keyboard comprising:

a plurality of keys arranged in an M row by N column matrix format;

a plurality of at least N light sources for generating N light beams, there being at least one light source for each column;

a first light transmission member having at least N common light transmission paths each for transmitting at least one of said light beams from one of said N light sources to M terminal points, there being a terminal point for each row;

a second light transmission member having at least M common light transmission paths, one for each row, each path having N light receptors, each N light receptor of a M light transmission path being aligned with a terminal point of a different light transmission path of said first light transmission member to form a light path therebetween;

a plurality of interrupters each responsive to the depression of different key and each uniquely located between a terminal point and corresponding light receptor for interrupting the light path therebetween upon key depression;

a plurality of M light sensors each aligned with a different one of said M light transmission paths for sensing the presence or absence of light transmitted along its associated second light transmission path;

logic means for timewise sequencing said light sources and for gating the output signals of said sensors to provide a logic indication indicating the depressed key;

wherein the improvement comprises;

said first light transmission member having a plurality of M reflecting surfaces along the transmission path of each of said N light beams, each reflecting surface deflecting a portion of its associated light beam vertically from its first plane of travel within said first transmission member to a second plane of travel within said first transmission member;

said first light transmission member having a second plurality of M reflecting surfaces for deflecting said portions of said light beams along a third plane of travel within said first transmission member vertically displaced from said first plane of travel and in a direction approximately orthogonal to the direction of travel of said light beam in said first plane of travel;

said second light transmission member having a plurality of at least N reflecting surfaces for each of said M light transmission paths for directing light from said light receptors to said light sensors along each M common light transmission path.

2. The keyboard of claim 1 wherein the size of each of said plurality of M reflecting surfaces is inversely proportional to its distance from its associated N light source.

3. The keyboard of claim 1 further including a support plate for supporting and guiding said plurality of keys, said support plate being integrally formed with said first light transmission member.

4. The keyboard of claim 1 or claim 3 wherein said first light transmission member includes N separate light transmission members, each separate light transmission member having M reflecting surfaces for deflecting said associated light beams vertically.

5. The keyboard of claim 1 wherein each of said second light transmission members has means associated therewith for each of said N light receptors for deflecting received light vertically to said M common transmission paths.