Inverse/complementary function prefix key

• US 3,892,958 A
• Filed: 01/11/1974
• Issued: 07/01/1975
• Est. Priority Date: 01/11/1974
• Status: Expired due to Term

• Current Assignee: Chung C. Tung
• Original Assignee: Chung C. Tung
• Inventors: Tung, Chung C.
• Primary Examiner(s): Malzahn, David H.
• Application Number:
  US05/432,736
• Time in Patent Office: 536 Days
• Field of Search: 235/156,145R,146 340/365R,365S,172.5
• US Class Current: 708/145
• CPC Class Codes: H03M 11/18 wherein the shift keys are operated before the operation of the multifunction keys

Abstract

A hand-held programmable calculator is specified, which has a prefix key for designating the inverse or complement of direct functions having legends on the keyboard thereof, thus expanding the utility of the keys on the keyboard.

Claims

1. An input and control keyboard for use in a calculator comprising:

a mounting panel for mounting keys;

a plurality of keys including function and numeric keys, mounted in the mounting panel, for activating input and control functions, each of said keys having more than two functions assigned thereto;

color-coded legends applied to the mounting panel adjacent to the keys for identifying one of the functions assigned thereto;

a first command key mounted in the mounting panel, having a color-coded body coloration for associating that key with functions identified by correspondingly color-coded legends; and

a command key legend affixed to the first command key for associating that key with the inverse of functions identified by the correspondingly color-coded legends;

said first command key being manually operable with one of the plurality of keys for designating the inverse of the function identified by the correspondingly color-coded legend assigned to that key.

2. The keyboard of claim 1 further including a second command key having a command key legend and a color-coded body coloration for associating that key with the direct functions identified by the correspondingly color-coded legends wherein said second command key is manually operable with one of the plurality of keys for designating the direct function assigned to that key.

3. The keyboard of claim 1 wherein each legend on the mounting panel identifies more than one of the functions assigned to the adjacent one of the plurality of keys.

4. The keyboard of claim 3 wherein each legend on the mounting panel identifies two functions assigned to the adjacent one of the plurality of keys.

5. The keyboard of claim 1 wherein the first command key is operable with one of the plurality of keys for designating the complement of the function identified by the correspondingly color-coded legend assigned to that key.

6. The keyboard of claim 5 further including a second command key having a command key legend and a color-coded body coloration for associating that key with the direct functions identified by the correspondingly color-coded legends wherein said second command key is manually operable with one of the plurality of keys for designating the direct function assigned to that key.

7. The keyboard of claim 5 wherein the first command key is operable with some of the plurality of keys for designating the inverse of the functions identified by the correspondingly color-coded legends assigned thereto and is operable with some others of the plurality of keys for designating the complement of the functions identified by the correspondingly color-coded legends assigned to the last-mentioned keys.

8. The keyboard of claim 7 wherein the first command key is depressed prior to depressing one of the plurality of keys.

9. The keyboard of claim 7 further including a second command key having a command key legend and a color-coded body coloration for associating that key with the direct functions identified by the correspondingly color-coded legends wherein said second command key is manually operable with one of the plurality of keys for designating the direct function assigned to that key.