JPH07143476A - Monitor signal changeover device - Google Patents

Abstract

PURPOSE:To eliminate disturbance of display on a screen when switching by switching in a timing based on a vertical synchronizing signal, eliminating the switching during vertical scanning and controlling the output mute of a picture signal in a predetermined timing based on the vertical synchronizing signal in a monitor signal after switching. CONSTITUTION:When a switching command is given to a switching signal generating section 11 at a point of time t0, a vertical synchronizing signal V. SYNC of an input 1 selected at present is checked to recognize that a monitor signal of the input 1 is in the vertical scanning state. Then switching control is not made to switching sections 21-25 at that point of time and the input of a synchronization pulse is awaited while monitoring the signal V.SYNC of the input 1 succeedingly. When a vertical synchronizing pulse is detected from the input 1 at a point of time t1, a switching execution signal is outputted to the switching sections 21-25 in the timing and the switching sections 21-25 are connected to a terminal t2 to switch the monitor signal of the input 1 to an input 2 in a timing within a vertical blanking period. The operation above is repeated to eliminate disturbance of a picture from the input 2 at a monitor television receiver.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitor signal switching device for switching a large number of image signals such as image signals branched from a plurality of monitor televisions and image signals from a television camera and supplying them to one monitor device. It is a thing.

[0002]

2. Description of the Related Art It has been a conventional practice to display a selected image on a single multi-scan monitor television by switching a large number of image signals such as an image signal branched from a plurality of monitor televisions and an image signal from a television camera. It is being appreciated.

FIG. 3 shows such a conventional video monitor device. In this figure, an image signal output from a machine tool or a television camera 31 for monitoring is input to a switching device 34 via a transmission path 37, and, for example, in a monitor television 32 displaying an operating state of a machine tool. The image signal obtained by branching the image signal is transmitted through the transmission path 38 to the switching device 34.
To the switching device 34 via the transmission path 39. Further, the image signal obtained by branching the image signal for displaying the screen on the monitor television 33 is input to the switching device 34.

The switching device 34 selects and outputs one of the input image signals according to the switching control signal from the switching control section 35. The image signal output from the switching device 34 is supplied to the multi-scan type video monitor television 36, and an image based on the selected image signal is displayed. The switching control unit 35 has a function of automatically selecting an input image signal sequentially and a function of manually switching to an image signal, and it is possible to select either one of the functions as required.

Although only two monitor televisions are shown, a plurality of monitor televisions are also provided. However,
These monitor televisions do not necessarily match in scanning frequency because manufacturers do not match and standards or the like differ. For this reason, the video monitor television 36 is of a multi-scan type so that an image can be normally displayed even if the scanning frequency is different.

In addition, the transmission lines 37 through which the image signal is transmitted.
Reference numeral 39 is a part of the transmission path 39, and is constituted by bundling five lines as shown in the drawing. this is,
Since the image signals are in the form of R, G, B signals and the scanning frequencies do not always match as described above, the vertical synchronization signal V. SYNC and horizontal sync signal H.264.
This is because it is also necessary to transmit SYNC.

The switching device 34 is constructed, for example, as shown in FIG. Corresponding to the monitor signal from the TV camera 31 and the monitor signals branched from the monitor televisions 32 and 33, a plurality of input units are provided as shown as input 1, input 2, ... R, G, and B video signals and a horizontal synchronizing signal H.H. SYNC, and the vertical sync signal V.V. SYNC is input. 41 to 45 are T
₁ through T _n terminal is provided in a switching unit terminals in synchronism, respectively, it is switched for connection.

The switching section 41 is adapted to supply the R signals at the inputs 1 to n to the terminals T _{1 to} T _n ,
The R signal supplied to the connected terminal among the T _{1 to} T _n terminals is output. Similarly, the T _{1 to} T _n terminals of the switching unit 42 are supplied with the G signals from the inputs 1 to n to be selectively output, and the T _{1 to} T _n terminals of the switching unit 43 are input from the inputs 1 to n. The B signal is supplied and selectively output. Also, the T ₁ through T _n terminal of the switching unit 44 a horizontal synchronizing signal from the input 1 to input n H. SYNC is supplied and selectively output, and the vertical synchronizing signals V.V. from the inputs 1 to n are input to the terminals T _{1 to} T _n of the switching unit 45. SYNC is supplied and selectively output.

Each of the switching units 41 to 45 includes a switching signal generating unit 50.
The connection terminal is switched according to the signal from. The switching signal generating section 50 executes the switching operation of each of the switching sections 41 to 45 in accordance with the switching command from the switching control section 35 shown in FIG. 3, and for example, the T ₁ terminal is connected in the switching sections 41 to 45. From the state in which the monitor signal of input 1 is output,
When the switching command for switching the output monitor signal to the input 2 is input, the switching units 41 to 45 are switched to the T ₂ terminal.

[0010]

However, the device for switching a plurality of monitor signals as described above has the following problems. Image signal (R, G, B), horizontal sync signal H. SYNC, vertical sync signal V. SYNC or these composite signals are switched at the same time, and the switching timing is set independently of the monitor signal by a timer or the like which counts a predetermined time in the case of user's operation or automatic switching. In many cases, the monitor signal that is selectively output is switched during the vertical scanning. Further, the monitor signals supplied to the inputs 1 to n are not synchronized.

For example, a case of switching from the input 1 to the input 2 will be described as an example. 5 (a) and 5 (b) are vertical synchronization signals V.V. SYNC
Is an example of. Here, it is assumed that the switching command is supplied at time t ₀ in the figure and each of the switching units 41 to 45 is switched from the t ₁ terminal to the t ₂ terminal. In this case, regarding the image signals (R, G, B) output from the switching device 34,
The output is switched from the image signal of the input 1 to the image signal of the input 2 at time t ₀ as shown in FIG.

However, at this time, if the image signal of the input 1 before switching and the image signal of the input 2 after switching match at the switching timing, the input on the screen of the video monitor television 36 is as shown in FIG. The images of 1 and input 2 are displayed on one screen in a state where they are separated in the middle, but in general, switching is rarely performed in a state where the synchronization relationship is the same. Since there is no switching of the synchronization, the result becomes very difficult as shown in FIG. 6 (b).

In particular, immediately after the switching, there is a problem that a disordered image continues until the video monitor television 36 is completely synchronized with the newly selected image signal.

[0014]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a monitor signal switching device which does not deteriorate the monitor screen quality in this way.

To this end, a plurality of input means to which a monitor signal composed of a vertical synchronizing signal, a horizontal synchronizing signal, and an image signal are respectively supplied, and a plurality of input means are selectively selected to select the selected input. The switching means for outputting the monitor signal supplied to the means is provided, and the mute means for muting the output of the image signal output from the switching portion, the switching command and the vertical synchronization in each monitor signal from each input means. When the signal is supplied and the switching command is input, the switching operation control of the switching means is performed at a predetermined timing generated based on the vertical synchronizing signal, and the predetermined timing generated based on the vertical synchronizing signal. The monitor signal switching device is configured by providing the control means capable of controlling the operation of the mute means.

More specifically, the control means controls the switching of the switching means at the timing at which the vertical synchronizing signal of the monitor signal at the input section selected at that time is detected after the switching instruction is input. To execute.

Further, the control means turns on the operation of the mute means at the timing when the vertical synchronizing signal of the monitor signal in the input section selected at that time is detected after the switching instruction is input, and the switching operation is performed. The operation of the mute means is turned off at the timing when the vertical synchronizing signal of the monitor signal in the input means selected by is detected.

[0018]

By performing the switching operation at the timing based on the vertical synchronizing signal, it is possible to eliminate the switching during the vertical scanning. Further, since the monitor signals before and after switching are not vertically synchronized, the image signal after switching is often not displayed at an appropriate scanning position by simply controlling the switching timing. It is possible to prevent an improper screen display by muting the output of the image signal at a predetermined timing based on the vertical synchronizing signal in the monitor signal after switching.

[0019]

1 shows a monitor signal switching device of the present invention.
In this figure, the video monitor signal switching device 10 is provided with an input section including an input 1 and an input 2 to an input n.
One of these input signals is selected and output. That is, similar to the switching device described with reference to FIG. 4, switching portions 21 to 25 are provided, and each has a terminal T.
_{1 to} T _n are R signals and G from each input section of input 1 to input n.
Signal, B signal, horizontal sync signal H. SYNC, vertical sync signal V. SYNC is supplied to each switching unit 2
From 1 to 25, monitor signals (R signal, G signal, B signal, horizontal synchronizing signal H.SYN) for the selected input section are selected.
C, vertical sync signal V. SYNC) is output.

A switch 12 is connected to the output side of the switching unit 21 so that the signal line and the ground can be connected and disconnected.
Similarly, the switch 13 is connected to the output side of the switching unit 22, and the switch 14 is connected to the output side of the switching unit 23.
That is, the switches 12 to 14 have R signal, G signal, and B signal, respectively.
It becomes a mute circuit for the signal and switches 12 to 14
The R signal, the G signal, and the B signal are not output from this switching device when the switch is closed.

Reference numeral 11 denotes a switching signal generator, which is supplied with a switching command from the switching controller 35 in the system as shown in FIG.
The switching operation of 5 is executed. Further, in this embodiment, the switching signal generator 11 includes the switches 12 to 12 as the mute circuit.
It also controls the on / off operation of 14. Further, with respect to the switching signal generating section 11, from each input section (input 1 to input n),
Vertical sync signal V. SYNC is branched and supplied, and when the switching signal generator 11 is supplied with the switching command, the vertical synchronization signal V.V. The operation timing is controlled by setting the switching timing and the mute timing using SYNC.

The switching operation of the switching device 10 will be described with reference to FIG. The operation when switching from input 1 to input 2 is taken as an example. 2A and 2B are vertical synchronization signals V.V. of the monitor signals at inputs 1 and 2. It is an example of SYNC. Here, it is assumed that a switching command is supplied to the switching signal generator 11 at time t ₀ in the figure. At this time, the switching signal generator 1
1 is the vertical sync signal V.1 for the currently selected input 1. Check out SYNC. Then, at time t _0, input 1
It can be seen that the monitor signal of is being vertically scanned. Therefore, at this time, the switching execution control is not yet performed on the switching units 21 to 25, and the vertical synchronization signal V.
Monitor SYNC and wait for sync pulse.

When a vertical sync pulse is detected for input ₁ at time t ₁ , a switching execution signal is output to the switching units 21 to 25 at that timing to cause the switching units 21 to 25 to operate. Connect to t ₂ terminal. That is, when the monitor signal of input 1 enters the vertical blanking period, input 2
Will be switched to.

By the way, at this point, the monitor signal of the newly selected input 2 is not necessarily in the vertical blanking period. Therefore, if the monitor signal of the selected input 2 is output as it is, in the system of FIG. 3, a difficult display will be displayed on the video monitor television 36.

Therefore, the switches 12 to 14 are turned on at substantially the same timing when the switching units 21 to 25 are switched, and the image signal to be output is muted (FIG. 2 (d)). Then, this time, the vertical synchronization signal V. SYN
Monitor C and wait for sync pulse.

When a vertical sync pulse is detected for input ₂ at time t ₂ , the switches 12 to 14 are activated at that timing.
Turn off to release the mute (Fig. 2 (d)), and input 2
Is supplied to the video monitor television 36, for example. The output of the image signal during this switching operation period is as shown in FIG. 2E, and a blank period due to the mute operation occurs during the transition from the image signal of the input 1 to the image signal of the input 2.

Then, the output of the image signal of the input 1 is finished within the vertical retrace line period of the image signal of the input 1, and the output of the image signal (R, G, B) of the input 2 is started. The video signal is input within the vertical blanking period of the image signal of the input 2 and the vertical and horizontal synchronizing signals are output during the mute period. Therefore, the video monitor television 36 side synchronizes the image signal of the input 2 during the mute period. Will be taken. Therefore, the disturbance of the image on the screen before and after the switching is eliminated. This makes it possible to display an image that is easy to see.

In addition to the example of FIG. 2, there are cases in which the signals before and after switching are synchronized, or cases in which the synchronization method is completely different (the number of scanning lines is different). Even if the vertical synchronizing signal V. SYNC
To obtain the switching timing, and the vertical synchronizing signal V.V. of the monitor signal at the switching time and after the switching. Image distortion can be eliminated by obtaining the timing of mute on / off in SYNC.

If there is a circumstance that the synchronization lock cannot be performed so quickly in the video monitor television 36, the mute period is set to be long, for example, one to several fields, or the video monitor television 36.
It is also possible to take measures to cancel the mute by detecting that the synchronization has been completely established. Further, in the case of the black and white video signal, the mute may be changed only to the luminance signal instead of the R, G and B signals.

The monitor signal switching device of the present invention as described above is a monitor device for monitoring, a monitor device for broadcasting, or an AV.
It can be used in a system or the like.

[0031]

As described above, the monitor signal switching device of the present invention eliminates the switching during the vertical scanning by executing the switching operation at the timing based on the vertical synchronizing signal, and the monitor signal after the switching. By performing the output mute control of the image signal at a predetermined timing based on the vertical synchronizing signal in (1), it is possible to prevent the screen display from being disturbed at the time of switching.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a monitor signal switching device of the present invention.

FIG. 2 is an explanatory diagram of a switching operation of the monitor signal switching device according to the embodiment.

FIG. 3 is a diagram showing a video monitor device to which a plurality of image signals are input.

FIG. 4 is an explanatory diagram of a conventional monitor signal switching device.

FIG. 5 is an explanatory diagram of a switching operation of a conventional monitor signal switching device.

FIG. 6 is an explanatory diagram of image distortion on the screen of the video monitor.

[Explanation of symbols]

 10 Switching device 11 Switching signal generation part 12-14 Switch 21-25 Switching part 31 Television camera 32, 33 Monitor TV 34 Switching device 35 Switching control part 36 Video monitor TV

Claims (3)

[Claims] 1. A plurality of input means to which a monitor signal composed of a vertical synchronizing signal, a horizontal synchronizing signal, and an image signal are respectively supplied, and the input means selected by selectively selecting the plurality of input means. Switching means for outputting the monitor signal supplied to the switch, a mute means for muting the output of the image signal output from the switching section, a switching command, and vertical synchronization in each monitor signal from the input means. When a signal is supplied and a switching command is input, the switching operation control of the switching means is performed at a predetermined timing generated based on the vertical synchronizing signal, and a predetermined timing generated based on the vertical synchronizing signal. A monitor signal switching device comprising: a control unit configured to control the operation of the mute unit at a timing. . 2. The control means executes the switching control of the switching means at the timing at which the vertical synchronizing signal of the monitor signal in the input section selected at that time is detected after the switching instruction is input. The monitor signal switching device according to claim 1. 3. The control means turns on the operation of the mute means at the timing when a vertical synchronizing signal of the monitor signal in the input section selected at that time is detected after the switching command is input, 3. The monitor signal switching device according to claim 1 or 2, wherein the operation of the mute means is turned off at the timing when the vertical synchronizing signal of the monitor signal in the input means selected by the switching operation is detected. .