JP2003101879A - Video switching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a required quantity of small scale video switching devices in the case of constituting a large scale video switching device by using the small scale video switching devices. SOLUTION: Input and output impedances of the small scale video switching devices 11-14 are set in two ways of a stipulated value and a high impedance. Then, a plurality of the small scale video switching devices 11-14 are arbitrarily paired on an input side and an output side, signals C1 and C2 or C3 and C4 are inputted in common to a terminal on the input side of the pair, the terminal on the output side of the pair is connected in common and the signals M1-M4 are taken out. For the small scale video switching devices 11-14, one of the input ends of the pair is set to a stipulated impedance, the other is set to the high impedance, similarly one of the output ends of the pair is set to the stipulated impedance, the other is set to the high impedance and the impedances at the signal input end and the signal output end are held at the stipulated value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video switching device for switching and displaying monitoring images of a plurality of television cameras on a plurality of monitors.

[0002]

2. Description of the Related Art Conventionally, in a monitoring system for monitoring the state of a plant, for example, when monitoring the monitor images from a plurality of TV cameras with a plurality of monitors, the monitor images sent from the plurality of TV cameras are switched. It is switched by the device and input to the monitor.

Conventionally, the above-mentioned video switching device has been appropriately selected and used from the following two systems: 1) a large-scale matrix switcher, 2) a combination of small-scale matrix switchers.

The method using the large-scale matrix switcher of 1) becomes extremely expensive when the number of cameras and monitors is several tens or more. Further, in the method of 2) combining small scale matrix switchers, the number of small scale matrix switchers required is extremely increased as the number of cameras and monitors increases.

A specific example of the method of 2) combining small scale matrix switchers is shown below.

FIG. 3 shows the configuration of a small-scale matrix switcher, that is, a small-scale video switcher 1.
The small-scale video switcher 1 is of a 2-input / 2-output (2 × 2) type and can arbitrarily switch the signals input to the two input terminals 2a and 2b and output them to the two output terminals 3a and 3b. It is like this.

FIG. 4 shows the 2 × 2 small-scale video switcher 1 described above.
4 shows an example of a case where a 4 × 4 large-scale video switching device 4 is configured using. The large-scale video switching device 4 is a
To c, each of the columns has four small-scale video switching devices 1. Row a small-scale video switcher 1a
Inputs input signals C1 to C4 to one input terminal and does not use the other input terminal. Then, the output signal of each small-scale video switch 1a in the row a is selected by the small-scale video switch 1b in the row b, and further, the small-scale video switch 1b in the row b is selected.
Output signals M1 to M4 are switched by the small-scale video switcher 1c in the c column.

The large-scale video switching device 4 uses the small-scale video switching device 1a in the row a as a video distribution function, and the small-scale video switching device 1c in the row c that constitutes an output stage as a video switching function. ing.

In the large-scale video switching device 4 configured as described above, the signals C1 to C4 input to the small-scale video switching device 1a in the row a are supplied to the small-scale video switching device 1b in the rows b and c.
By switching with 1c, the input signals C1 to C4 can be arbitrarily selected and can be used as the output signals M1 to M4.

[0010]

When the large-scale image switching device 4 is constructed by using the small-scale image switching device 1 as described above, conventionally, the distribution amplification function at the first stage and the image switching function at the output stage are required. Therefore, the small-scale video switch 1 (1a
1 to 1c) must be configured in three columns, and a very large number of small-scale video switchers 1 are required. For example, when the large-scale video switching device 4 having 4 inputs and 4 outputs (4 × 4) is configured, 12 small scale video switching devices 1 are required.

Since the input and output impedances of the conventional small-scale video switch 1 are set to the specified values,
If they are connected in parallel, there is a problem that the quality of the video signal deteriorates remarkably due to the reduction of the input impedance and the collision of the output signals. For this reason, conventionally, the small-scale video switchers 1 cannot be connected in parallel, and a very large number of small-scale video switchers 1 are required when configuring the large-scale video switcher 4.

The present invention has been made to solve the above-mentioned problems, and when a large-scale video switching device is constructed by using a small-scale video switching device, the required number of small-scale video switching devices is significantly increased. An object is to provide a video switching device that can be reduced.

[0013]

A video switching apparatus according to the present invention comprises a plurality of small-scale video switches each having a plurality of inputs and a plurality of outputs, and a plurality of the plurality of small-scale video switches on the input side. The output side includes means for arbitrarily forming a pair, means for commonly inputting a video signal to the input side terminals of the pair, and means for commonly connecting the output side terminals of the pair to take out signals. The small-scale video switcher comprises input impedance setting means for switching and setting the input impedance between a specified value and high impedance, and output impedance setting means for switching and setting the output impedance between a specified value and high impedance. Is characterized by.

As described above, the input impedance and the output impedance of the small-scale image switching device can be set in two ways, the specified value and the high impedance, so that two small-scale image switching devices are connected in parallel in pairs. However, by setting one input and output impedance of the pair to the specified value and setting the other input and output impedance to the high impedance, the impedance of the signal input terminal and the output terminal can be maintained at the specified value. It will be possible. Therefore, when a large-scale video switching device is configured using a plurality of small-scale video switching devices, the distribution amplification function and the video switching function of the output stage, which were required in the past, can be eliminated, and the required number of small-scale video switching devices can be eliminated. Can be significantly reduced.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a small-scale video switcher 11 having a plurality of inputs and a plurality of outputs, such as two inputs and two outputs (2 × 2).
4 shows an example of a case where a large-scale video switching apparatus 10 having 4 inputs and 4 outputs (4 × 4) is configured using 14. That is, the input signals (video signals) C1 and C2 are input to the input terminals of the small-scale video switcher 11 and also to the input terminals of the small-scale video switcher 13. Also, the input signal C
3 and C4 are input to each input terminal of the small-scale video switcher 12 and each input terminal of the small-scale video switcher 14.

The signals output from one of the output terminals of the small-scale image switching devices 11 to 14 are used as the output signals M1 to M4 of the large-scale image switching device 10, and the other signals of the small-scale image switching device 11 are output. The signal output from the output terminal is M2, the signal output from the other output terminal of the small scale video switch 12 is M1, the signal output from the other output terminal of the small scale video switch 13 is M4, the small scale. Video switcher 1
The signal output from the other output terminal of 4 is M3.

FIG. 2 shows the small-scale image switching devices 11-14.
2 is a detailed circuit configuration of the above. Input terminal 21
a and 21b are connected to the input ends of the buffer amplifiers 22a and 22b, respectively. This buffer amplifier 22a, 2
The input terminals of 2b are connected to switches 23a and 23b and resistors 24a and 24 having a prescribed impedance, for example, 75Ω.
It is grounded through b. The switches 23a and 23b
Is set to an on / off state manually or by a switching signal from the outside.

As the buffer amplifiers 22a and 22b, those having a high input impedance and a low output impedance, for example, an input impedance of infinity (∞) and an output impedance of 0Ω are used, and the output signals thereof are 2 inputs / 2 outputs. Output circuits 26a, 2
6b is input. In the switching circuit 25, the input / output connection state is set by a control signal from the outside.

As the output amplifiers 26a and 26b, those having a high input impedance and a low output impedance, for example, an input impedance of infinity (∞) and an output impedance of 0Ω are used, and their output signals are switches 27a and 27b, respectively. And 75Ω resistors 28a and 28b
Is connected to the output terminals 29a and 29b via. As the switches 27a and 27b, for example, electronic switches such as semiconductor switches are used, and their on / off states are switched by a switching signal from the outside. Signals are switched by the switching circuit 25, and the switch 27a or the switch 2 is used.
The input signal can be arbitrarily selected by turning on 7b.

In the large-scale video switching apparatus 10 configured as described above, when the switches 23a and 23b on the input side are turned on, the input impedance is 75Ω and the switches 23a and 23b.
When b is turned off, the input impedance becomes infinite. In addition, the large-scale video switching device 10 has a switch 27 on the output side.
When a and 27b are turned on, the output impedance is 75Ω,
When the switches 27a and 27b are turned off, the output impedance becomes infinite.

When the large-scale video switching device 10 shown in FIG. 1 is constructed by using the small-scale video switching devices 11 to 14, the small-scale video switching device 11 to which the input signals C1 and C2 are commonly input. , 13, the switch 23 of one of the selectors
a and 23b are turned on, and switches 23a and 2 of the other selector are turned on.
Set 3b off. For example, when the switches 23a and 23b of the small-scale video switch 11 are turned on, the switches 23a and 23b of the small-scale video switch 13 are set to the off state. That is, the total input impedance of the small-scale video switchers 11 and 13 for the input signals C1 and C2 is always maintained at 75Ω.

Similarly, in the small-scale image switching devices 12 and 14 to which the input signals C3 and C4 are commonly input, the switches 23a and 23b of one switching device are turned on and the switches 23a and 23b of the other switching device are turned on. Set it to off and keep the total input impedance at 75Ω.

The small-scale video selectors 11 and 12 to which the output signals M1 and M2 are commonly connected, when the switch 27a or the switch 27b of one of the selectors is turned on, the switch 27a of the other selector. Or switch 2
Set 7b off. That is, the output signals M1 and M2
The total output impedance of the small-scale video switches 11 and 12 is always maintained at 75Ω.

Similarly, in the small-scale video selectors 13 and 14 to which the output signals M3 and M4 are commonly connected, when the switch 27a or the switch 27b of one of the selectors is turned on, the switch 27a of the other selector is switched. Or switch 2
7b is set to off and the total output impedance is always 7
It should be maintained at 5Ω.

As described above, each small-scale video switcher 11 to 1
4, the switches 23a and 23b are provided on the signal input side, the switches 27a and 27b are provided on the signal output side, and when two switches are connected in parallel, when one switch is turned on, the other switch is turned on. Turned off and the input impedance and output impedance are always 75
Since it is held at Ω, each small-scale video switcher 1
Even if the input side and the output side of 1 to 14 are connected in parallel so as to form a pair, the input signals C1 to C4 can be taken out as the output signals M1 to M4 without any trouble, that is, without deterioration in quality.

Therefore, as shown in FIG. 1, the large-scale video switching apparatus 10 is constituted by the single-stage small-scale video switching devices 11-14.
It is possible to eliminate the need for the distribution amplification function and the video switching function of the output stage, which are conventionally required, and it is possible to greatly reduce the required number of small-scale video switching devices.

In the above embodiment, the case where the switches 23a and 23b are provided in each of the small-scale image switching devices 11 to 14 has been described. However, the switching device in which the input impedance is set to the specified value and the high input impedance are set. The same purpose as in the above-described embodiment can be achieved even if the above-mentioned switch is prepared in advance and these two kinds of switch are used in combination as a pair. In this case, switch 2
A configuration in which 3a and 23b are omitted can be adopted.

[0028]

As described above in detail, according to the present invention, the input and output impedances of the small-scale video switcher can be set to two types, that is, the specified value and the high impedance. Even if two pairs are connected in parallel as a pair, it is possible to maintain the impedance at the signal input end and the output end at the specified impedance. Therefore, when a large-scale video switching device is configured using a plurality of small-scale video switching devices, the distribution amplification function and the video switching function of the output stage, which were required in the past, can be eliminated, and the required number of small-scale video switching devices can be eliminated. Can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a video switching device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing details of a small-scale video switching device in the same embodiment.

FIG. 3 is a diagram showing a basic configuration of a conventional small-scale video switching device.

FIG. 4 is a configuration diagram of a large-scale video switching device configured by combining a plurality of conventional small-scale video switching devices.

[Explanation of symbols]

10 ... Large-scale video switching device 11-14 ... Small-scale video switching device 21a, 21b ... Input terminals 22a, 22b ... Buffer amplifier 23a, 23b ... switch 24a, 24b ... Resistance 25 ... Switching circuit 26a, 26b ... Output amplifier 27a, 27b ... switch 28a, 28b ... Resistance 29a, 29b ... Output terminals

Claims (6)

[Claims] 1. A multi-input / multi-output video switching device for arbitrarily switching multi-input video signals to produce multiple outputs, and an input terminal set to a prescribed input impedance,
The apparatus is provided with signal switching means for arbitrarily switching the signal input to the input terminal and outputting it to the signal output terminal, and output impedance setting means for switching and setting the output impedance of the signal output terminal between a specified value and a high impedance. A video switching device characterized by the above. 2. A multi-input / multi-output video switching device for arbitrarily switching multi-input video signals to provide multiple outputs, and an input end set to an input impedance higher than a specified value and the input end. And a signal switching unit for arbitrarily switching the output signal to the signal output end, and an output impedance setting unit for switching and setting the output impedance of the signal output end between a specified value and a high impedance. Switching device. 3. A multi-input / multi-output video switching device for arbitrarily switching multi-input video signals to provide multiple outputs, wherein an input impedance setting for switching and setting the input impedance of a signal input terminal between a prescribed value and a high impedance. Means, signal switching means for arbitrarily switching the signal input from the signal input terminal and outputting the signal to the signal output terminal, and output impedance setting means for switching and setting the output impedance of the signal output terminal between a specified value and a high impedance. An image switching apparatus comprising: 4. A multi-input / multi-output video switching device for arbitrarily switching multi-input video signals to produce multiple outputs, and first and second buffer amplifiers for amplifying the multi-input signals, respectively. A first switch for switching and setting the input impedances of the first and second buffer amplifiers to a specified value and a high impedance respectively, and a plurality of inputs / a plurality of outputs for switching and outputting the output signals of the first and second buffer amplifiers. Switching circuit, and first and second output amplifiers for amplifying the output signals of the switching circuit, respectively,
A video switching device comprising: a second switch for switching and setting the output impedances of the first and second output amplifiers to a specified value and a high impedance, respectively. 5. A plurality of small-scale video switches each having a plurality of inputs and a plurality of outputs, and a means for arbitrarily configuring a pair of the plurality of small-scale video switches on the input side and the output side. The pair of input side terminals commonly inputs a video signal, and the pair of output side terminals are commonly connected to extract a signal, and the small-scale video switcher defines an input impedance. An image switching device comprising: an input impedance setting means for switching and setting a value and a high impedance; and an output impedance setting means for switching and setting an output impedance between a specified value and a high impedance. 6. A plurality of small-scale video switches each having a plurality of inputs and a plurality of outputs, and a means for arbitrarily configuring a pair of the plurality of small-scale video switches on the input side and the output side. The pair of input side terminals commonly inputs a video signal, and the pair of output side terminals are commonly connected to extract a signal, and the small-scale video switcher defines an input impedance. The input impedance setting means for switching and setting the value and the high impedance, and the output impedance setting means for switching and setting the output impedance between the specified value and the high impedance, and one small scale of the pair by the input impedance setting means. Set the input impedance of the video switch to the specified value and the input impedance of the other small-scale video switch to high impedance, The output impedance of one of the small picture switcher forming the pair by-impedance setting means the specified value, the video switching apparatus characterized by setting the output impedance of the other small video switcher to a high impedance.