KEYBOARD ASSEMBLY

• US 3,623,082 A
• Filed: 05/27/1970
• Issued: 11/23/1971
• Est. Priority Date: 05/27/1970
• Status: Expired due to Term

• Current Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Original Assignee: Mark S. Stein, Richard F. Maier, Robert I. Foster
• Inventors: Stein, Mark S., Maier, Richard F., Foster, Robert I.
• Primary Examiner(s): Murray, Richard
• Application Number:
  US05/040,829
• Time in Patent Office: 545 Days
• Field of Search: 340/345,347,365,166,172.5,171
• US Class Current: 341/26
• CPC Class Codes: H03M 11/20 Dynamic coding, i.e. by key scanning H03M11/26 takes precedence

Abstract

A keyboard assembly for detecting closures in a plurality of switches places in rows and columns to form a matrix or keyboard, each switch representing a distinct data item, includes a signal source continuously operating first and second shift registers in asynchronous relation to each other to provide a distinct register setting for each of the switches. Whenever one of the switches is closed, a control circuit interrupts or arrests the continuous operation of the first and second shift registers in the distinct setting representing the closed switch and shortly thereafter supplies a strobe signal to enable a data utilization device to receive a coded representation of the distinct setting from a read only memory coupled to and controlled by the first and second shift registers.

Claims

1. A scanning circuit for detecting changes in the state of a plurality of data items, said scanning circuit comprising:

a plurality of switching means operable in random order, each of said switching means representing one of the distinct data items, continuously operable counting means including separate counting portions operated in an asynchronous relation to each other to different and distinct settings, each setting representing one of said switching means, output means coupled to and controlled by the counting means for supplying a distinct coded representation for each setting of the counting means, each setting representing one of said data items, a detector means coupled to the counting means and controlled by the counting means and the switching means, and control means coupled to the detector means and the counting means and controlled by the detector means for arresting operation of the counting means in a setting corresponding to an operated switching means.

2. A scanning circuit as set forth in claim 1 wherein the switching means are placed in rows and columns to form a cross-point matrix.

3. A scanning circuit as set forth in claim 1 wherein each of the switching means is operable by the manual depression of a key on a keyboard unit.

4. A scanning circuit as set forth in claim 1 wherein the separate counting portions are first and second shift registers.

5. A scanning circuit as set forth in claim 2 wherein the separate counting portions are first and second shift registers, said first shift register being coupled to the columns of the said matrix, and said second shift register beinG coupled to the detector means

6. A scanner circuit as set forth in claim 1 wherein the detector means includes a plurality of NAND gates, the outputs of the said NAND gates being coupled to a common output of the detector means.

7. A scanner circuit as set forth in claim 1 wherein the control means includes a NAND gate coupled to the detector means and interrupting the operation of the counting means.

8. A scanning circuit as set forth in claim 1 including a data utilization device coupled to said output means.

9. A scanning circuit as set forth in claim 8 wherein the control means includes a strobe generator that enables the data utilization device to receive a coded representation of the arrested setting of the counting means from the output means.

10. A scanning circuit as set forth in claim 9 including an input means coupled to said strobe generator and operable to alternate states, one of said states being a potential of one polarity and the other state being a potential of opposite polarity.

11. A scanning circuit as set forth in claim 8 wherein said output means includes a read only memory to supply the coded representation for each setting of the counting means, and a plurality of output gates coupled to said read only memory to transmit the coded representation to the data utilization device.

12. A scanning circuit as set forth in claim 11 wherein said read only memory includes a plurality of encoders, and a selecting means to enable one of said encoders to receive and encode the output of said counting means.

13. A scanning circuit as set forth in claim 11 including an output means coupled to said output gates and operable to alternate states, one of said states being a potential of one polarity and the other state being a potential of opposite polarity.

14. A scanning circuit for detecting changes in the state of a plurality of data items and supplying a distinct coded representation of the data items to a data utilization device, said scanning circuit comprising:

a plurality of switching means operable in random order and placed in rows and columns to form a matrix, each of said switching means representing one of the distinct data items, continuously operable counting means including first and second shift registers operated in asynchronous relation to each other to different and distinct settings, each setting representing one of said switching means, output means coupled to and controlled by the counting means for supplying the distinct coded representation for each setting of the counting means, each setting representing one of said data items, a detector means coupled to the second shift register and to the rows of the matrix and controlled by the setting of the first and second shift registers and the switching means, and control means coupled to the detector means and the counting means and controlled by the detector means for arresting operation of the counting means in a setting corresponding to an operated switching means and for enabling the data utilization device to receive the coded representation corresponding to the arrested setting of the counting means.

15. A keyboard assembly comprising:

a plurality of keys, each key representing a distinct data item, a plurality of switching means, each of said switching means controlled by one of said keys, a plurality of conductors arranged in rows and columns, each of said conductors coupled to one of said switching means to form a matrix so that each row conductor is directly connectable to each column conductor by one of said switching means, a first counting means having a plurality of stages, each of said stages being directly coupled to one of said column conductors and being sequentially driven to a reference potential, a detector means having an input directly coupled to each of said row conductors, a second counting means having a plurality of stages, each stage being coupled to another Input of said detector means, a control means coupled to the output of said detector means, said control means inhibiting said first and second counting means whenever said detector means simultaneously receives a signal from a stage of said second counting means and a signal of a reference potential from a stage of said first counting means through a closed switching means, and an output means coupled to and controlled by said first and second counting means.

16. A keyboard assembly comprising:

a plurality of randomly operable keys, each of said keys representing a data item, a plurality of switching means, each of said switching means controlled by one of said keys, continuously operable counting means including separate counting portions operated in an asynchronous relation to each other to different and distinct settings, each setting representing one of said keys, output means coupled to and controlled by the counting means for supplying a distinct coded representation for each setting of the counting means, a detector means coupled to the counting means and controlled by the counting means and the switching means, and control means coupled to the detector means and the counting means and controlled by the detector means for arresting operation of the counting means in a setting corresponding to a switching means that has been operated in response to an operated key.

17. A keyboard assembly for detecting and encoding changes in the state of a plurality of data items, said keyboard assembly comprising:

a plurality of switching means operable in random order, each of said switching means representing one of the distinct data items, continuously operable first and second counting means operated to different and distinct settings, each setting representing one of said switching means, said second counting means coupled directly to each of said switching means, output means coupled to and controlled by the first and second counting means for supplying a distinct coded representation for each setting of the first and second counting means, each setting representing one of said data items, a detector means directly coupled to said first counting means and to each of said switching means and controlled by the first and second counting means and the switching means, and control means coupled to the detector means and the first and second counting means and controlled by the detector means for arresting operation of the first and second counting means in a setting corresponding to an operated switching means.