GB2148653A - Picture-phone apparatus - Google Patents

Abstract

A transceiver for transmission and reception of video information via a telephone line is described. The transceiver includes a photosensitive imaging array 11 and means for coding an image focussed on the array into a digital signal. This signal is transmitted to a remote station via an acoustic coupler 17 whereby the transceiver is coupled to the line. The transceiver also includes a decoding circuit and a display 18 for presentation of information received from the remote station. <IMAGE>

Description

SPECIFICATION Communications apparatus This invention relates to communications apparatus, and in particular to apparatus for transmitting and receiving visual information via a telephone line.

According to the invention there is provided a transreceiver for transmitting to and receiving from a similar remote station visual informAtion via a telephone line, the transeceiver including an acoustic coupler whereby, in use, coupling to a telephone line is effected, means for scanning and encoding said visual information in the form of a digital code, a memory for storing said code and for storing code signals received from a remote station, a display associated with the memory whereby the visual information corresponding to a stored code may be displayed, and control means whereby the apparatus is switched to a transmit or a receive mode.

An embodiment of the invention will now be described with reference to the accompanying drawing in which the single figure is a schematic diagram of a transceiver apparatus.

Referring to the drawing, the transceiver includes a photosensitive imaging array 11 and an associated lens system 1 2 whereby an image may be focussed on the array. The array incorporates a scan and encode circuit 1 3 which in use generates a digital data code corresponding to the visual information, which circuit 1 3 is coupled to a random access memory 14 wherein the data code is stored.

Data stored in the memory 1 5 may be output to a telephone line for transmission to a similar remote station via a modem circuit 1 6 and an acoustic coupler 1 7 which in use is coupled to the handset of a telephone instrument (not shown). Similarly, data signals received from the remote station via the line are fed through the modem circuit to the memory 1 5. The memory is also coupled to a display 18, e.g. a liquid crystal display, via a drive circuit 19 for'displaying the memory contents to the user.

Operation of the transceiver is controlled by a control logic circuit 20 which switches the receiver between its transmit and receive modes either automatically or in response to a user input signal Advantageously the imaging array 11 comprises a custom 6144 bit dynamic RAM chip the package of which may incorporate the lens 1 2. In operation the RAM is filled with logic ONE's and is then read (96 X 64 cells) eight times. Brightly illuminated cells change their data state before the first scan whilst darker cells change at later scans. This provides an eight stage grey scale which is adequate for most purposes. However an improved grey scale can be provided by reducing the VDD voltage between reading scans.

The video information derived in this manner is coded in the form of 3-bit binary words which are then stored in the RAM. the three bit code providing black, white and six intermediate grey levels.

In a further embodiment the transceiver may incorporate means for storing on a magnetic tape or disc the audio signal that is output for the acoustic coupler and/or the audio signal that is received from a remote station over a telephone line.

1. A transreceiver for transmitting to and receiving from a similar remote station visual information via a telephone line, the transeceiver including an acoustic coupler whereby, in use, coupling to a telephone line is effected, means for scanning and encoding said visual information in the form of a digital code, a memory for storing said code and for storing code signals received from a remote station, a display associated with the memory whereby the visual information corresponding to a stored code may be displayed, and control means whereby the apparatus is switched to a transmit or a receiver mode.

2. A transceiver as claimed in claim 1, and including a photo-detector comprising a random access memory.

3. A transceiver as claimed in claim 2, and including means for filling the random access memory with logic ONE's, said ONE's decaying at a rate corresponding to the intensity of incident light, and means for periodically reading the memory to obtain a digital video code.

4. A transceiver as claimed in claim 3, and including means for encoding the output of the photodetector as a series of 3 bit binary numbers and storing these in a second, larger, random access memory.

5. A transceiver as claimed in claim 1, 2 or 3, and including means for tape or disc storage of digitally coded video information.

6. A transeiver substantially as described herein with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Communications apparatus This invention relates to communications apparatus, and in particular to apparatus for transmitting and receiving visual information via a telephone line. According to the invention there is provided a transreceiver for transmitting to and receiving from a similar remote station visual informAtion via a telephone line, the transeceiver including an acoustic coupler whereby, in use, coupling to a telephone line is effected, means for scanning and encoding said visual information in the form of a digital code, a memory for storing said code and for storing code signals received from a remote station, a display associated with the memory whereby the visual information corresponding to a stored code may be displayed, and control means whereby the apparatus is switched to a transmit or a receive mode. An embodiment of the invention will now be described with reference to the accompanying drawing in which the single figure is a schematic diagram of a transceiver apparatus. Referring to the drawing, the transceiver includes a photosensitive imaging array 11 and an associated lens system 1 2 whereby an image may be focussed on the array. The array incorporates a scan and encode circuit 1 3 which in use generates a digital data code corresponding to the visual information, which circuit 1 3 is coupled to a random access memory 14 wherein the data code is stored. Data stored in the memory 1 5 may be output to a telephone line for transmission to a similar remote station via a modem circuit 1 6 and an acoustic coupler 1 7 which in use is coupled to the handset of a telephone instrument (not shown). Similarly, data signals received from the remote station via the line are fed through the modem circuit to the memory 1 5. The memory is also coupled to a display 18, e.g. a liquid crystal display, via a drive circuit 19 for'displaying the memory contents to the user. Operation of the transceiver is controlled by a control logic circuit 20 which switches the receiver between its transmit and receive modes either automatically or in response to a user input signal Advantageously the imaging array 11 comprises a custom 6144 bit dynamic RAM chip the package of which may incorporate the lens 1 2. In operation the RAM is filled with logic ONE's and is then read (96 X 64 cells) eight times. Brightly illuminated cells change their data state before the first scan whilst darker cells change at later scans. This provides an eight stage grey scale which is adequate for most purposes. However an improved grey scale can be provided by reducing the VDD voltage between reading scans. The video information derived in this manner is coded in the form of 3-bit binary words which are then stored in the RAM. the three bit code providing black, white and six intermediate grey levels. In a further embodiment the transceiver may incorporate means for storing on a magnetic tape or disc the audio signal that is output for the acoustic coupler and/or the audio signal that is received from a remote station over a telephone line. CLAIMS

1. A transreceiver for transmitting to and receiving from a similar remote station visual information via a telephone line, the transeceiver including an acoustic coupler whereby, in use, coupling to a telephone line is effected, means for scanning and encoding said visual information in the form of a digital code, a memory for storing said code and for storing code signals received from a remote station, a display associated with the memory whereby the visual information corresponding to a stored code may be displayed, and control means whereby the apparatus is switched to a transmit or a receiver mode.

2. A transceiver as claimed in claim 1, and including a photo-detector comprising a random access memory.

3. A transceiver as claimed in claim 2, and including means for filling the random access memory with logic ONE's, said ONE's decaying at a rate corresponding to the intensity of incident light, and means for periodically reading the memory to obtain a digital video code.

4. A transceiver as claimed in claim 3, and including means for encoding the output of the photodetector as a series of 3 bit binary numbers and storing these in a second, larger, random access memory.

5. A transceiver as claimed in claim 1, 2 or 3, and including means for tape or disc storage of digitally coded video information.

6. A transeiver substantially as described herein with reference to the accompanying drawing.