Image transmission system

Claim 1

An image transmission apparatus for use in a system which includes a monitored side with a plurality of sites to be monitored, each site having a television camera (16A - 16D) for sensing an image of the site, a monitoring side equipped with monitors (81-84) by which the images of the sites can be monitored or watched, and a transmission line (14) connecting therebetween, the frequency bandwidth of which is divided into plural transmission channels, comprising an instruction signal transmitting means (20) provided in the monitoring side for producing an instruction signal by the operation of an operator and transmitting it to the monitored side, an instruction signal receiving means (40) provided in the monitor side for receiving and interpreting the instruction signal to produce control signals, an image signal transmitting means (50) provided in the monitored side for receiving image signals picked up by the television cameras (16A - 16D) and transmitting to the monitoring side an image transmission signal formed by processing the image signals from the television cameras in accordance with the control signals produced by the instruction signal receiving means (40), and an image signal receiving means (30) provided in the monitoring side for receiving and processing the image transmission signals to supply the image signals picked up by the television cameras to the monitors (81-84), characterized i n that the instruction signal includes a code signal in which a code assigned to each of the television cameras is arranged in the order selected by the operator, a first group of codes including at least one code located at the predetermined position within the arrangement of codes being so specified that the image signals picked up by the cameras assigned the codes of the first group are transmitted as full motion images and a second group of codes consisting of the remaining codes being so specified that the image signals picked up by the cameras assigned the codes of the second group are transmitted as frame repetition images, that the image signal transmitting means (50) has first image storages (501, 502, 504, 505) for full motion images, each of which stores the image signal picked up by the camera assigned one of the codes of the first group, and second image storage (503, 506) for frame repetition images which stores the image signals picked up by the cameras assigned the codes of the second group alternately at a predetermined period, whereby the image transmission signal is so formed in said image signal transmitting means that one of the plural transmission channels of the transmission line is occupied for the transmission of each of the image signals stored in the first image storages and all of the image signals stored in the second image storage are multiplexed on the time-sharing basis and transmitted through the remaining transmission channels, and that the image signal receiving means (30) separates the received image transmission signal into first image signals of the full motion images and second image signals of the frame repetition images to display the first image signals on the respective monitors as the full motion images and to demultiplex the second image signals thereby to supply them to other respective monitors.