Infrared communication device for multistandard operations

• US 5,617,236 A
• Filed: 08/15/1994
• Issued: 04/01/1997
• Est. Priority Date: 08/15/1994
• Status: Expired due to Term

• Current Assignee: Actisys Corp.
• Original Assignee: Actisys Corp.
• Inventors: Yeh, Keming, Wang, Li-Chen
• Primary Examiner(s): PASCAL, LESLIE C
• Application Number:
  US08/290,330
• Time in Patent Office: 960 Days
• Field of Search: 359/174-176, 359/172, 359/137, 359/152-153, 375/214
• US Class Current: 398/117
• CPC Class Codes: G06F 13/385 for adaptation of a particular data processing system to different peripheral devices
• CPC Class Codes: H04B 10/1143 Bidirectional transmission
• CPC Class Codes: H04B 10/40 Transceivers

Abstract

An IR interface device is connected over a wired port to a host computer, so as to provide an IR communication link between the host computer and another computing device capable of IR communication. Such an IR interface device may also include a coupling to a printer device. An IR conference device allows communication between devices using different IR communication protocols by providing individual IR communication links to each of the communicating devices and passing data between the individual IR communication links. An IR transceiver integrated circuit with automatic gain control is provided.

Claims

1. An infrared radiation (IR) interface device, comprising:

a wired port, connecting said IR interface device to a host computer, for receiving from said host computer a first data stream and for providing to said host computer a second data stream;

an IR transceiver for transmitting data modulated for transmission as IR signals, and for receiving modulated data from IR signals detected;

a modulation circuit, coupled to said IR transceiver and receiving a third data stream, modulating said first data stream to provide said data modulated for transmission;

a demodulation circuit coupled to said IR transceiver, receiving from said IR transceiver said received modulated data to provide a fourth data stream;

a program memory for storing a control program for said IR interface device;

a data memory for temporarily storing data; and

a central processing unit, coupled to said wired port, said program memory, said data memory, said modulation circuit, and said demodulating circuit, for executing said control program, so as (i) to store into said data memory said fourth data stream, (ii) to send as said third data stream said first data stream received over said wire port from said host computer to said modulation circuit;

(iii) to retrieve said fourth data stream from said data memory and (iv) to send as said second data stream to said host computer said fourth data stream retrieved from data memory.

2. An IR interface device as in claim 1, further comprising a second wired port for providing to a second device said data received by said IR interface device.

3. An IR interface device as in claim 1, further comprising a power supply circuit, said power supply circuit receiving power from one of the following sources:

(i) an external power supply, (ii) a battery housed in said IR interface device, and (iii) a signal of said host computer coupled to said wired port.

4. An infrared radiation (IR) interface device as in claim 1, wherein said IR transceiver comprises:

a control circuit for processing data received and data to be transmitted as IR signals;

a subcarrier generator circuit for generating a subcarrier signal;

a modulator circuit, coupled to said control circuit and said subcarrier generator circuit, for modulating said data to be transmitted with said subcarrier signal to provide a modulated data signal;

a driver circuit for driving an external light emitting diode in accordance with said modulated data signal;

a receiver circuit for (i) amplifying and detecting IR signals received in an external photodetector and (ii) providing said IR signals to said control circuit as said data received;

an automatic gain control circuit, coupled to said receiver circuit for adjusting the gain in said receiver circuit, in accordance with strengths of said IR signals received; and

a transmitter-active detection circuit for detecting a transmission time of said data to be transmitted, and for disabling said automatic gain control circuit for a period of time equal to said transmission time plus a predetermine time period.

5. An infrared radiation (IR) interface device as in claim 4, wherein said IR transceiver further includes a power management circuit, said power management circuit providing a "power-down" signal when said power management circuit detects a time period of a predetermined length during which neither data received nor data to be transmitted are processed in said control circuit.

6. An infrared radiation (IR) interface device as in claim 4, wherein said IR transceiver receives control signals from a host device at a predetermined baud rate.

7. An infrared radiation (IR) interface device as in claim 4, further comprising a power supply circuit for receiving power from said host computer over said wired port, said wired port having a ground terminal for coupling to a ground terminal of said host computer, said power supply circuit comprising:

a ground terminal coupled to said ground terminal of said wired port to form a common ground terminal;

a diode having an anode and a cathode, said anode of said diode being coupled to a signal line of said wired port;

a capacitor coupled between said common ground terminal and said cathode of said diode, such that said signal line charges said capacitor through said diode with a charging current;

a step-down voltage converter coupled to said capacitor for providing a supply current larger than said charging current in said signal line; and

a power supply terminal for coupling said supply current to circuits in said IR interface device.

8. An infrared (IR) interface device as in claim 7, wherein said signal line attains a voltage higher than a voltage at said power supply terminal.

9. An infrared (IR) interface circuit as in claim 7, wherein said signal line is coupled in series to a resistor for limiting currents in said first and second diodes.

10. An infrared (IR) interface device as in claim 4, wherein said wired port is a RS232C port, said IR interface device operating at CMOS voltage levels, and wherein said signal line carries an output signal of said RS232C port.

11. An infrared (IR) interface device as in claim 4, wherein said host computer is a palmtop computer.

12. An infrared radiation (IR) conference device, comprising:

a housing including first and second windows suitable for transmitting IR signals;

first and second IR transceivers, each IR transceiver located within said housing behind a corresponding window for transmitting data as IR signals through said corresponding window, and for receiving modulated data from IR signals detected through said corresponding window; and

a central processing unit, coupled to said first and second IR transceivers, for (i) demodulating data received at said first window from a first device, in accordance with a first signal modulation scheme, and modulating said data received at said first window, in accordance with a second signal modulation scheme, for transmission at said second window to a second device, and (ii) demodulating data received at said second window from said second device, in accordance with said second signal modulation scheme, and modulating said data received at said second window, in accordance with said first signal modulation scheme, for transmission at said first window to said first device.

13. An IR conference device as in claim 12, wherein said central processing unit establishes (i) a first communication link with said first device, in accordance with a first protocol, and (ii) a second communication link with said second device, in accordance with a second protocol.

14. An IR conference device as in claim 12, further comprising a third window, wherein said central processing unit modulates data received from said first device at said first window for transmission at said third window to a third device, in accordance with a third signal modulation scheme, simultaneously modulating said data received from said first device at said first window for transmission at said second window to said second device, in accordance with said second signal modulation scheme.

15. An IR conference device as in claim 12, further comprises a non-volatile semiconductor memory for storing firmware executed by said central processing unit.

16. An IR interface device as in claim 12, further comprising a random access memory for storing data received by said IR conference device.

17. An IR conference device as in claim 12, further comprising a power supply circuit, said power supply circuit receiving power from one of the following sources:

(i) an external power supply, and (ii) a battery housed in said housing.

18. An infrared radiation (IR) interface device, comprising:

a first interface circuit, including a serial port connector, for transmitting data and receiving data to and from a serial port of a first electronic device coupled via said serial port connector;

an IR transceiver circuit for receiving and transmitting IR signals in accordance with a signal demodulation scheme and a signal modulation scheme, respectively;

a programmable protocol control logic circuit, coupled to said first interface circuit and said IR transceiver circuits, said programmable protocol control logic circuit being programmable by said first electronic device over said serial port, for (i) receiving said demodulated IR signals, extracting data from said demodulated IR signals, and providing said extracted data to said first interface circuit for transmission to said first electronic device;

(ii) receiving data from said electronic device, and providing said data received from said first electronics device to said interface circuit, for transmission as IR signals under said signal modulation scheme.

19. An infrared radiation (IR) interface device as in claim 18, wherein said IR transceiver circuit and said protocol control logic circuit is included in an IR transceiver integrated circuit.

20. An infrared radiation (IR) interface device as in claim 18, wherein said IR interface device is powered by said electronic device via a signal line in said serial connector.

21. An infrared radiation (IR) interface device, comprising:

a first interface circuit, including a serial port connector, for transmitting data and receiving data to and from a serial port of a first electronic device coupled via said serial port connector;

an IR transceiver circuit for receiving and transmitting IR signals in accordance with a signal demodulation scheme and a signal modulation scheme, respectively;

a protocol control logic circuit, coupled to said first interface circuit and said IR transceiver circuits, for (i) receiving said demodulated IR signals, extracting data from said demodulated IR signals, and providing said extracted data to said first interface circuit for transmission to said first electronic device;

(ii) receiving data from said electronic device, and providing said data received from said first electronics device to said interface circuit, for transmission as IR signals under said signal modulation scheme;

wherein said first electronic device comprises a parallel-to-serial interface device, said parallel-to-serial interface device comprising;

a second interface circuit, including a parallel port connector, for transmitting data and receiving data from a parallel port of a second electronic device coupled via said parallel port connector; and

an embedded controller, coupled to said second interface circuit for (i) providing said data received from said parallel port of said second electronic device serially to said first interface circuit via said serial port connector; and

(ii) providing said data transmitted on said serial port to said second interface circuit for transmission to said second electronic device over said parallel port.

22. An infrared radiation (IR) interface device as in claim 21, further comprising static random access memory accessed by said embedded controller.

23. An infrared radiation (IR) interface device as in claim 21, wherein said embedded controller includes a mask-programmed read-only memory.