JPH0429874A - Dispersion-type multiplexer for transmitting and receiving video signal - Google Patents

Abstract

PURPOSE:To save a trouble in connecting operation and reduce the cost of a cable by a method wherein R, G, B primary color signals inputted from a host computer are changed over in time series to be transmitted to one cable, and vertical and horizontal synchronizing signals are synthesized to be transmitted to one cable. CONSTITUTION:A video signal change-over circuit 21 changes over R, G, B primary color signals for one frame inputted from a host computer in the predetermined order and transmits the signal in time series. The order is assigned from a color hard copying machine 10 through a communication control part 25. A synchronizing signal synthesizing circuit 22 receives a horizontal synchronizing signal H and a vertical synchronizing signal V and outputs the both in a synthesized state. In this manner, the R, G, B primary color signals for one frame inputted from the host computer are not transmitted in parallel but in time series. Therefore, the R, G, B primary color signals can be transmitted through one coaxial cable 1. In addition, since the horizontal and vertical synchronizing signals are transmitted in a synthesized state, only one coaxial cable may be required for transmitting the synchronizing signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention comprises a plurality of distributed multiplexers, one multiplexer selected by one color hardcopy device connected to the multiplexer. The present invention relates to a distributed multiplexer device that inputs a color video signal from a host computer directly or through one or more other multiplexers preceding the multiplexer to the color hardcopy device.

[Conventional technology]

FIG. 5 shows a system of this type including a host computer HCPU, a multiplexer MPX and a color hardcopy device. In the same figure, HCP
U, 1 is a host computer with an image memory, MPX, . . . are distributed multiplexers, and 10 is a color hardcopy device.

M P Switch to the side, MPX,
switches the output switching circuit to the MP
XZ) red (R), green (G), blue (B) from TCPU2
The primary color signals and the horizontal synchronization signal H1 and the vertical synchronization signal I are sent to the color hardcopy device 10 through five coaxial cables 1 to 5. Signals G and B are output, respectively, and a horizontal synchronization signal H and a vertical synchronization signal ■ are output to coaxial cables 4 and 5, respectively.

The color hardcopy device 10 receives the input RlG, H
The signals are A/D converted and each signal is stored in a frame memory (not shown), color converted, and printed on paper.

[Problem to be solved by the invention]

In this way, in a system with multiple HCPUs and multiple MPXs, MPX, ~MPX, , mutual and MPX
, and the color hard copy device 10, six coaxial cables 1 to 6 (at least 4 cables) are required, so there is a problem that the connection work takes time, and
PX, ~MPX.

Inter and MPX, and color hardcopy device 10
Since the coaxial cables are generally arranged at intervals of 10 m to several tens of m, there is a problem in that the cost of the coaxial cable becomes high.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a distributed multiplexer device for transmitting and receiving video signals that can reduce the number of required coaxial cables by half.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a distributed multiplexer having one output terminal to which a communication cable is connected, one video signal output terminal, and one synchronization signal output terminal as output terminals. A video signal switching circuit that inputs R, G, and B video signals and outputs them in time series;
Controlled by a synchronization signal synthesis circuit that inputs and synthesizes vertical synchronization signals, a synchronization switching circuit that selects either the output of this synchronization signal synthesis circuit or one of the primary color signals, an output switching circuit, and a color hard copy device. The configuration includes a communication control section that receives signals and controls switching of each switching circuit.

[Effect]

The multiplexer of the present invention passes the R, G, and B primary color signals inputted from the host computer through the video signal output terminal in time series in the order specified by the color hard copy device by the video signal switching circuit. The vertical and horizontal synchronization signals are combined in a synchronization signal synthesis circuit, and this synthesized synchronization signal is sent to the color hardcopy device or other multiplexer in the previous stage through the synchronization signal output terminal. multiplexer.

That is, the R, G, and B primary color signals are transmitted in time series through one coaxial cable, and the horizontal and vertical synchronization signals are combined and transmitted through one coaxial cable.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, the multiplexer M P X + is
It is equipped with a video signal switching circuit 21, a synchronization signal synthesis circuit 22, a synchronization switching circuit 23, an output switching circuit 24, and a communication control section (microprocessor) 25, and the output terminals include a synchronization signal output terminal 31, a video signal output terminal 32, A control signal output terminal 33 is provided. Further, as input terminals, it has a synchronization signal input terminal 34, a video signal input terminal 35, a control signal input terminal 36, and a group of connection terminals 37 to 41 for connecting to the HCP. In the same figure, S
A I”S A T is an analog switch, and AMP is a video amplifier.

The video signal switching circuit 21 switches the R, G, and B primary color signals for one frame inputted from the HCP in a predetermined order and outputs them in time series. This order is specified from the color hardcopy device 10 through the communication control unit 25. The synchronization signal synthesis circuit 22 has the configuration shown in FIG. 3, takes in the horizontal synchronization signal H and the vertical synchronization signal V, synthesizes both signals, and outputs the result. In FIG. 3, r1 to r5, r are resistors, and OPAMP is an operational amplifier. Synchronous switching circuit 23
selects the output of the synchronization signal synthesis circuit 22 or the G signal depending on the video signal output form of the HCP U (composite synchronous type, separate synchronous type, or composite synchronous sync-on-green type). . If it is a composite synchronous sync-on-clean type, turn on analog switches A S6 and A S7, respectively.
In the case of separate synchronous type and composite synchronous type, analog switches AS6 and AS7 are turned OFF and ON, respectively. The output switching circuit 24 is connected to the communication control section 25
When a selection command is received from the When receiving a selection command, M
The video signal (R, G, and B primary color signals are arranged in time series) inputted from PX2 and the synchronization signal are sent to the video signal output terminal 32 and the synchronization signal output terminal 31, respectively. The communication control section 25 receives a control signal sent from the color hard copy device 10 and controls the video signal switching circuit 21, the synchronization switching circuit 23, and the output switching circuit 24.

When a composite synchronization signal is input, the color hard copy device 10 separates it into vertical and horizontal synchronization signals, and A/D converts the R, G, and B primary color signals input in time series. , stored in the corresponding frame memory.

In this way, in this embodiment, the R and GXB primary color signals for one frame inputted from the host computer are not sent out in parallel, but for example, as shown in FIG. After sending only the R signal, the G signal is sent,
After sending out the G signal, the B signal is outputted in time series, so that the R, G, and B primary color signals can be sent through one coaxial cable 1.

Furthermore, since the horizontal and vertical synchronization signals are combined and sent, only one coaxial cable is required for transmitting the synchronization signals.

〔Effect of the invention〕

As explained above, the present invention switches the R, G, and B primary color signals input from the host computer in time series and sends them out to one cable, and combines the vertical and horizontal synchronization signals and sends them to one cable. Since it is transmitted between MPXs, color and
Only three cables are required to connect the hard copy device and the MPX, reducing the effort required for connection and the cost of cables compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a connection state of a distributed multiplexer device using a multiplexer according to the present invention, FIG. 2 is a block diagram showing the internal configuration of the multiplexer, and FIG. 3 is a synchronization signal synthesis circuit in FIG. 2. FIG. 4 is a signal waveform diagram in the above embodiment, and FIG. 5 is a diagram showing the connection state of a conventional distributed multiplexer. 1 to 6 - coaxial cable, 10 - color hard copy device, 21 - video signal switching circuit, 22 synchronous signal synthesis circuit, 23 - synchronous switching circuit, 24 output switching circuit, 25 - communication control unit, 31 to 33 - output Terminals, 34-36-input terminals, HCP
TJ, ~HCPU, - Host Computer, MPX. ~MPXwaichi multiplexer.

Claims (1)

[Claims] Consisting of a plurality of distributed multiplexers, one
A multiplexer selected by the color hardcopy device may transmit the color video signal from the host computer connected to the multiplexer directly or to one or more other color hardcopy devices located closer to the color hardcopy device than the multiplexer. In a distributed multiplexer device that inputs input to the color hard copy device through a multiplexer, each multiplexer has one output terminal to which a communication cable is connected, one video signal output terminal, and one synchronization signal output terminal as output terminals, A video signal switching circuit that inputs R, G, and B three primary color signals from a corresponding host computer and outputs them in time series; a sync signal synthesis circuit that inputs and synthesizes horizontal and vertical synchronization signals from the host computer; It has a synchronization switching circuit, an output switching circuit, and a communication control unit that inputs the output of the signal synthesis circuit and one of the three primary color signals and selects one of them, and the output switching circuit inputs the output of the signal synthesis circuit and one of the three primary color signals and selects one of them. Select one of the synchronous output set of the switching circuit and the time series output and synchronous output set of the adjacent multiplexer, and send the time series output to the above video signal output terminal and the synchronous output to the above synchronous signal output terminal. the communication control unit determines the switching order of the video signal switching circuit based on the control signal received from the color hard copy device through the communication cable;
A distributed multiplexer device for transmitting and receiving video signals, characterized in that it controls switching of the synchronous switching circuit and the output switching circuit.