JPH06253212A - Broad band matrix switcher - Google Patents

Abstract

PURPOSE:To reduce power consumption of the switcher by providing a vibration function stop circuit for a buffer amplifier located at a pre-stage of a switch function to the matrix switcher in addition to a switch function of a cross point and applying ON/OFF control to the operation of the amplifier in interlocking with selection/non-selection of an input signal. CONSTITUTION:Circuit blocks 7-1, 7-2-7-n with an input buffer and switch circuits 3-5 arranged to them are arranged to plural input signals 1-1, 1-2-1-n and output signals selected by collecting output lines are outputted via an output buffer 8. The processing above is the same as a conventional matrix switcher, but in this invention, a dissolve circuit 6 is provided in interlocking with the switch circuit. For example, when a signal inputted to the block 7-1 is selected, the circuits 3, 4 are turned on and the circuit 5 is turned off and an operating current is supplied from the circuit 6 to the buffer in interlocking with above to allow the buffer to provide a signal and no operating current is supplied from the circuit 6 to the buffer 2 by turning off the circuits 3, 4 and turning on the circuit 5 in other blocks than the block 7-1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide band video signal switching device, and more particularly to a wide band matrix switcher.

[0002]

BACKGROUND OF THE INVENTION Generally, the signal amplification circuit over a wide frequency range, especially tens MH _Z frequency higher than the case of obtaining a flat characteristic, to minimize the effects of stray capacitance of the input and output capacitance and circuit elements Therefore, the impedance is low, and the circuit constant is set to increase the operating current to obtain the required output signal. Further, in a matrix switcher having a function of taking out only a necessary signal from a large number of signals by providing a switching circuit, unnecessary signals leak more at higher frequencies due to elements and wiring of the switching circuit.

An example of a conventional technique will be described with reference to FIG. 2 by limiting to a plurality of inputs and one output. Multiple input signals 1-1, 1-
Circuit blocks 9-1, 9-2, ... 9-n in which an input buffer 2 and a signal transmission switchgear (hereinafter referred to as a switch circuit) 3, 4 are arranged for each of 2 ,. The output lines of the switch circuit 4 of the block are collected and the selected output signal is output from the output buffer 6. In addition, when the switch circuits 3 and 4 are in the open state, in order to prevent deterioration of off isolation due to the capacitance between contacts, the switch circuit 5
Was closed.

Here, the circuit blocks 9 must be arranged as close to each other as possible in order to collect their output lines and guide them to the output buffer 8. Therefore, the amount of crosstalk between each circuit block was large. In addition, since the input buffer 2 has a low impedance in order to obtain a flat frequency characteristic, it is necessary to supply a large amount of operating current. Although not shown, when the switch circuits 3, 4, 5 are operated to select any one of the input signals 1-1, 1-2, ... 1-n, the switch circuits 3, 4 of other circuit blocks are selected. 4,5
Performs the reverse operation to the above, and the control circuit is configured so as not to output other input signals.

[0005]

As described above, since the signal output lines are gathered and led to the output buffer, it is necessary to arrange the circuit blocks of each signal system adjacent to each other. For this reason,
The amount of crosstalk between circuit blocks was large, impeding the performance of the matrix switcher. Moreover, since a large amount of operating current is supplied to the input buffer, the amount of power consumption is large and the amount of heat generated is large. An object of the present invention is to eliminate these drawbacks and to provide a small-sized, high-performance, wide-band matrix switcher in which the crosstalk is reduced and the current consumption is reduced.

[0006]

In order to achieve the above object, the present invention provides a matrix switcher with a crosspoint switch function, and a buffer amplifier (hereinafter referred to as “dissolve”) circuit provided in the preceding stage of the buffer amplifier.
The operation of the input buffer amplifier is ON / OFF controlled in association with selection / non-selection of each input signal.

[0007]

As a result, by activating the dissolve circuit (stopping the operation of the input buffer) with respect to the input buffer from which the input signal is not selectively output, the signal output of the buffer disappears and crosstalk can be prevented. Further, as described above, the power consumption is small because the input buffer that is not selectively output does not operate. Therefore, the power consumption of the matrix switcher itself can be reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. For each of the plurality of input signals 1-1, 1-2, ... 1-n, circuit blocks 7-1, 7-2, ... 7-n in which an input buffer 2 and switch circuits 3, 4, 5 are arranged are provided. Then, the output lines are assembled and the selected output signal is output via the output buffer 8.

Up to this point, the method is the same as the conventional method, but in the present invention, the dissolve circuit 6 interlocked with the switch circuit is installed. For example, when the signal input to the circuit block 7-1 is selected, the switch circuits 3 and 4 of this block are turned on and 5 is turned off, and in conjunction with this, the dissolve circuit 6 supplies the operating current to the input buffer. To output the signal. At this time, except for the circuit block 7-1,
The switch circuits 3 and 4 are turned off and the switch circuit 5 is turned on, so that the dissolve circuit 6 does not supply an operating current to the input buffer 2 and does not output a signal. Therefore, it is possible to prevent signals other than the input signal 1-1 from leaking into the circuit block 7-1 and at the same time reduce power consumption.

Although not shown in FIG. 1, the control for operating the switch circuits 3, 4, 5 and the dissolve circuit 6 is performed in conjunction with the selection of the input signal. In the above, the dissolve circuit of the circuit block of the system where the input signal is not selected does not supply the operating current to the buffer. However, in this case, the buffer does not operate so that the input current is It is possible to prevent noise from occurring when the selection of the signal is changed, that is, when the buffer is switched from non-operation to operation.

The buffer 2, the dissolve circuit 6, and the switch circuits 3, 4, and 5 can be replaced with respective one ICs that perform the same operation without being composed of different circuit elements. The actual matrix switcher has a plurality of inputs and a plurality of outputs, and in each input system in FIG. 1, the output of the input buffer 2 is distributed to a plurality of switch circuits corresponding to the plurality of outputs. Then, the output lines of each switch circuit are collected for each predetermined output system of each input system, and are led to the output terminal via each output buffer. In the product to which the present invention is applied, in the case of a video matrix switcher having 8 inputs and 4 outputs with 5 channels (R, G, B, HD, VD) per 1 input signal system, frequency band: 150 MH
z (-3 dB), crosstalk: -50 dB (60 MH
z), power consumption: 100W, crosstalk is 1
We were able to improve it by over 0 dB and reduce power consumption by 20%.

[0012]

As described above, according to the present invention, the input buffer operates only in the circuit block of the selected input signal system, so that the crosstalk can be greatly reduced. In addition, since the operating current is not supplied to the input buffer of the non-selected input signal system, the heat generation amount is also reduced. Therefore, it is possible to realize a high performance, small size and low power consumption wide band matrix switcher.

[Brief description of drawings]

FIG. 1 is a partial systematic diagram of a matrix switcher of the present invention.

FIG. 2 is a partial system diagram of a conventional matrix switcher.

[Explanation of symbols]

 1-1, 1-2, ... 1-n input signal 2 input buffer 3, 4, 5 switch circuit 6 dissolve circuit 7-1, 7-2, ... 7-n circuit block 8 output buffer

Claims (2)

[Claims] 1. A matrix switcher for selecting and outputting a single or a plurality of arbitrary signals from a plurality of wideband video signals, and supplying an operating current to an input buffer by interlocking with the selection and deselection of each signal to be output. Respectively ON,
A wide-band matrix switcher characterized by reducing the amount of unnecessary signal leakage and current consumption by turning it off. 2. The wide band matrix switcher according to claim 1, wherein when the operating current supply to the input buffer is turned off, a minute current that does not generate an output signal flows.