JP2893998B2 - Digital signal switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal switch, and more particularly to a digital signal switch applied to a television signal transmission system.

[0002]

2. Description of the Related Art Conventionally, when a plurality of digital input signals are switched and extended to a large number of output strings and transmitted, as shown in FIG.
, A plurality of switching devices 21 to 21 connected in cascade
23. The input distributor 20 includes a plurality of buffer amplifier circuits 2 corresponding to the respective input signals S1 to Sn.
01 to 20n are provided. In addition, each switch 21, 22, 22,
23, buffer amplifier circuits 201 to 201 of the input distributor 20
N input terminals X11 to X11 for receiving output signals from
X1n, X21~X2n, X31~X3n, and black
M output terminals Y11~Y1m for outputting a signal selected by the scan point unit, Y21~Y2m, Y31~Y
3 m each. Now, if such switches are connected in a z-stage cascade, the output sequence can be expanded to z × m.

[0003]

As described above, conventionally, when an output sequence is expanded, a plurality of input signals are respectively supplied to a plurality of switches via an input distributor. However, since the number of signals that can be distributed by the input distributor is limited, there is a problem that the number of connectable switchers, that is, the expansion of the output string is limited.

An object of the present invention is to provide a digital signal switch capable of expanding an output sequence without being limited by the number of switchers that can be connected.

[0005]

SUMMARY OF THE INVENTION A digital signal switch according to the present invention comprises a plurality (n) of receiving a plurality of (n ) input signals.
) Input terminals and whether the plurality (n) of the input signals
And a crosspoint section to select m
Multiple plurality (m pieces) switch that Ru each comprise an output terminal of the cascade of outputting the m signals that cement unit selects
(Z) connected digital signal switches,
The switch is, a plurality (n pieces) of the distribution times <br/> path of the plurality of (n) of 2 to distribute respectively connected to the input signal to the input terminals, respectively, these distribution circuit , The input terminal
A first inverter which receives the input signal and inverts the polarity and outputs the inverted signal
And the polarity of the output signal of the first inverter
Second invar which is inverted and supplied to the cross point portion
Receiving the output signal of the first inverter and receiving the output signal of the first inverter.
Connected to the input terminal of the next-stage switch connected in cascade.
And a third inverter to be supplied .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.
The figure shows a state in which switches 11, 12, and 13 are connected in cascade in order to switch a plurality of digital input signals and extend and transmit the output signals to a large number of output strings. Each switch 11, 1
Reference numerals 2 and 13 denote n input terminals X11 to X1n, X21 to X2n, and X31 to X3 that receive a plurality (n) of input signals.
n and m output terminals Y11 to Y1m, Y21 to Y2 for outputting a signal selected by the cross point unit
m, Y31 to Y3m. In each of the switches 11, 12, and 13, one-input / two-output distribution circuits 111 to 1n1, including two inverters for each input terminal, are provided.
211-2n1, 311-3n1 are provided, respectively. Each distribution circuit receives the input signal from the input terminal
A first inverter for inverting and outputting the polarity, and the first inverter;
Receives the output signal of the inverter and reverses the polarity to cross point
A second inverter supplying the first inverter and a first inverter
The next stage that receives the output signal and reverses the polarity and is cascaded
And the third inverter that supplies the input terminal of the switch
It is configured.

Now, a plurality of digital input signals S1 to S
n is supplied to the input terminals X11 to X1n of the first switch 11 connected in cascade, respectively. Distribution circuit 1
One output, which is divided into two by 11-1n1, is connected to the input terminal X21 of the switch 12 connected to the next stage.
To X2n. Similarly, one of the two outputs divided by the distribution circuits 211 to 2n1 of the switch 12 is connected to the input terminals X31 to X31 of the next-stage switch 13.
3n.

As described above, if the switches are connected in a z-stage cascade, the output sequence can be expanded to z × m.

In general, when the number of cascade stages increases, a time difference occurs between the rise and fall of the signal, and there is a problem that the signal width changes and exceeds the allowable limit. However, according to the present invention, by using two inverters, it is possible to correct a change in signal width due to a rise and fall time difference of a signal between the preceding inverter and the succeeding inverter.

[0011]

As described above, according to the present invention, a one-input two-output distribution circuit comprising two stages of inverters is provided for each input terminal of each switch, and one output divided by this distribution circuit is divided into two. , The output string can be expanded without being limited by the number of switches that can be connected.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing an example of a conventional digital signal switch.

[Explanation of symbols]

 11-13 Switcher 111-3n1 Distribution circuit X11-X3n Input terminal Y11-Y3m Output terminal S1-Sn Input signal

Claims (1)

(57) [Claims] A plurality of (n) input signals are received.
An input terminal of the (n-number) of the input signal of the plurality of (n)
A cross point part to select m pieces from within , and this cross
A plurality (m) of outputting m signals selected by the point section
A plurality (z number) digital signal switching device formed by connecting the output terminal and the switching device in cascade Ru with respective pieces), the switch is input is connected to the input terminals of the plurality of (n) A plurality (n) of force signals
Has a distribution circuit respectively, these distribution circuit, the input
The first in which the input signal from the terminal is inverted and the polarity is inverted and output
An inverter and an output signal of the first inverter;
The second point supplied to the cross point part after the polarity is inverted.
Receiving the output signal of the inverter and the first inverter
The input terminal of the next-stage switch that is polarity-inverted and cascaded
And a third inverter for supplying the digital signal to the digital signal switch.