Low power optical transceiver for portable computing devices

• US 5,075,792 A
• Filed: 03/20/1989
• Issued: 12/24/1991
• Est. Priority Date: 03/20/1989
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Moore, Lester S., Brown, Preston D., York, Dennis C.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): NEGASH, KINFE MICHAEL
• Application Number:
  US07/326,140
• Time in Patent Office: 1,009 Days
• Field of Search: 455/606, 455/603, 455/607, 455/608, 455/619, 455/617, 341/69
• US Class Current: 398/115
• CPC Class Codes: H04B 10/1143 Bidirectional transmission
• CPC Class Codes: H04B 10/40 Transceivers

Abstract

Optical transceiver (22) for calculator-to-calculator or calculator-to-module communication. The transceiver (22) includes an IR transmitter (24) and IR receiver (26) designed for use in the low power, low cost environment of calculators and portable computing devices. The transceiver may be adapted to communicate with the CPU (central processing unit (14) of a calculator (90) directly or with that of a portable computing device via its serial port (43). Devices in which the optical transceiver may be incorporated include calculators, plugless modules, and books containing plugless modules. Data such as mathematical formulas within the book may be stored in the associated module and transferred instantaneously and accurately to an adjacent calculator upon request by the calculator.

Claims

1. Apparatus for optical communication, comprising,

a data processor for processing information as the information is transmitted or received at a given bits per second rate

and for formatting the information for transmission from a nonreturn to zero bit format to a return to zero bit format and for reception from a return to zero bit format to a nonreturn to zero bit format;

and

an optical transceiver coupled to the data processor for transmitting and receiving the information so formatted, the optical transceiver comprising an IR transmitter and IR receiver, the IR receiver further comprising;

a phototransistor for receiving an IR signal;

a first transistor having its collector coupled to the base of phototransistor and its base coupled to the emitter of the phototransistor for compensating for the effects of ambient light on the conducting threshold of the phototransistor;

a capacitor coupled between the base of the first transistor and ground for filtering the effects of the received IR signal from the effects of ambient light on the operation of the first transistor; and

a second transistor having its base coupled to the emitter of the phototransistor and base of the first transistor for converting the received IR signal to a corresponding signal interpretable by the data processor.

2. The apparatus of claim 1 wherein the optical transceiver (22) comprises an IR transmitter (24) and IR receiver (26), the transceiver (22) operable by the data processor (14) in half duplex communication.

3. The apparatus of claim 1 including a hand-held portable computing device having a keyboard and display in which the data processor and optical transceiver are embedded, the computing device further including a pressable key for initiating the transmission or reception of data through the optical transceiver.

4. Apparatus for processing information and communicating such information optically, comprising:

a portable electronic computing device including a data processor, data entry means and a display, the computing device capable of manipulating data and acting on instructions entered through the data entry means and for displaying data as it is entered and processed;

a self-contained power source within the computing device for providing power to the device;

an optical transceiver within the computing device including an IR transmitter and IR receiver constructed to operate on power provided by the self-contained power source, the transceiver for transmitting information including data and instructions processed by the computing device optically and for receiving information optically to be processed by the computing device, the IR receiver including;

a photoresistor for receiving IR pulses, each individual pulse representing a bit;

a first transistor having its collector coupled to the base of the phototransistor and its base coupled to the emitter of the phototransistor for compensating for effects of ambient light on the conducting threshold of the phototransistor;

a capacitor coupled between the base of the first transistor and ground for filtering the effect of the received IR pulses from the effect of ambient light on the operation of the first transistor; and

a second transistor having its base coupled to the emitter of the phototransistor and base of the first transistor for converting the received IR pulse to a corresponding signal interpretable by the computing device;

memory within the computing device for storing information including data and instructions, some of the instructions for processing information and other instructions for transmitting and receiving information optically, the memory storing information entered through the data entry means for transmission via the optical transceiver and for storing information received via the optical transceiver;

a data processor coupled to the power source, memory and optical transceiver and programmed for processing information entered through the data entry means or received via the optical transceiver, the data processor further programmed for reformatting information for transmission from a non-return to zero format to a return to zero format and for reception from a return to zero format to a non-return to zero format; and

means within the data entry means for initiating the transmission or reception of information via the optical transceiver,

the computing device thereby able to optically receive information from an external source for processing and able to optically transmit information to an external destination.

5. The apparatus of claim 4 wherein the data entry means comprises a keyboard and the computing device comprises a calculator.

6. Apparatus for enabling a computer to transmit and receive IR signals via a serial port of the computer, comprising:

formatting means coupled to the serial port for formatting signals transmitted from the serial port from a nonreturn to zero bit format to a return to zero bit format and for formatting signals to be received by the serial port from a return to zero bit format to a nonreturn to zero bit format;

an IR transmitter coupled to the formatting means for receiving signals having a return to zero format and transmitting such signals as IR pulses;

an IR receiver coupled to the formatting means for receiving IR pulses having a return to zero bit format and passing such signals to the formatting means, the IR receiver including;

a phototransistor for receiving an IR signal;

a first transistor having its collector coupled to the base of phototransistor and its base coupled to the emitter of the phototransistor for compensating for the effects of ambient light on the conducting threshold of the phototransistor;

a capacitor coupled between the base of the first transistor and ground for filtering the effects of the received IR signal from the effects of ambient light on the operation of the first transistor; and

a second transistor having its base coupled to the emitter of the phototransistor and base of the first transistor for converting the received IR signal to a corresponding signal interpretable by the formatting means.