Infra-red data communications system for coupling a battery powered data entry device to a microcomputer

• US 4,628,541 A
• Filed: 02/15/1985
• Issued: 12/09/1986
• Est. Priority Date: 08/10/1983
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Beavers, John A.
• Primary Examiner(s): ORSINO JR, JOSEPH
• Application Number:
  US06/702,282
• Time in Patent Office: 662 Days
• Field of Search: 455/603, 455/608, 455/618, 455/617, 455/619, 375/96, 375/68
• US Class Current: 398/106
• CPC Class Codes: G06F 3/0227 Cooperation and interconnection of the input arrangement with other functional units of a computer G06F3/023 - G06F3/037 take precedence
• CPC Class Codes: G06F 3/0231 Cordless keyboards

Abstract

A battery powered keyboard entry device includes an infra-red generator for coupling the device to a microcomputer which includes an infra-red receiver. Each input binary signal is transmitted as a few (e.g. two or three) short infra-red pulses indicating the leading edge of the binary signal. In the receiver, the received groups of pulses, after detection and amplification, are stretched by a single-shot circuit to produce binary signals of substantially the same length as the original binary signals. As each transmission is substantially shorter than each binary signal, power consumption in the keyboard entry device is substantially reduced as compared with a system in which the infra-red pulses for each input signal extend over the input signal length.

Claims

1. An infra-red data communications system for coupling a battery powered keyboard data entry device to a microcomputer, in which said keyboard data entry device comprises means, including a microprocessor, for developing, in response to each keystroke, a binary data signal stream representing a start bit followed by a predetermined fixed number of data bits, each binary data signal comprising a predetermined signal level for a fixed period, and for driving an infra-red generator to develop, from each binary data signal, a single burst of infra-red pulses, of which the first pulse corresponds to the leading edge of the binary data signal, said burst extending for a period substantially less than half of the period of the binary data signal, and in which the microcomputer includes means for detecting and amplifying said bursts of infra-red pulses, and signal generating means coupled to the output of the detecting and amplifying means and responsive to detection of an initial pulse in a received burst comprising, when propagation loss is encountered, at least one but less than all of the developed burst of pulses, to generate an output binary code signal comprising a predetermined signal level for said fixed period and having a leading edge corresponding to said initial pulse, said microcomputer further including a microprocessor responsive to the lagging edge of the output signal representing the start bit to generate a series of sampling pulses to sample the output signals representing the data bits.

2. An infra-red communication system according to claim 1 in which each said single burst of infra-red pulses comprises two or more pulses extending for a period of one-fifth or less of the period of a coded data signal.

3. An infra-red communications system according to claim 1 in which said signal generating means comprises a single shot circuit set to a period corresponding to said fixed period.

4. An infra-red communications system according to claim 3 in which said single burst of infra-red pulses comprises two or more pulses extending for a period of one-fifth or less of the period of a coded data signal.