JPH077679A - Video signal switching device - Google Patents

Abstract

PURPOSE:To prevent the erroneous recognition of the fault of a receiver given to a user when external input is non-signal in a satellite broadcast reception tuner or the like for switching internal (reception) signals and external input signals. CONSTITUTION:This device is provided with a switching circuit 2 for switching the reception video signals S1 of the receiver and video signals V1 from an external input terminal, a video signal detection part 3 for detecting the presence/absence of the video signals V1 of the external input terminal and a control part 4 for controlling the changeover of the switching circuit 2. When the switching circuit 2 is set on the side of selecting the external input V1 of the external input terminal, a set state is maintained when the video signals are detected in the video signal detection part 3 and the switching circuit 2 is automatically switched to the side of the reception video signals S1 when the video signals are not detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal switching device for switching between a video signal from one or a plurality of external input terminals provided and a received signal in a satellite broadcast receiving tuner, a color television receiver or the like. .

[0002]

2. Description of the Related Art Generally, a satellite broadcast receiving tuner, a color television receiver or the like is provided with one or a plurality of external input terminals, and a user receives a video signal received by the receiver itself or an external input. Any of the video signals from the terminals can be freely selected and switched. But,
In the past, when the user switched to the external input terminal side and the external video signal is not input due to the external device being powered off or being set to a vacant channel, the screen goes black (cut off). become,
It can happen that you mistakenly recognize it as a failure.

[0003]

In order to prevent the above-mentioned erroneous recognition, the present invention selects the video signal when the user switches to the external input terminal side and the external video signal is not input. It is an object of the present invention to provide a video signal switching device that is automatically switched to.

[0004]

According to the present invention, there is provided a switching circuit for switching between a video signal received by a receiver and a video signal from one external input terminal, and a video for detecting the presence or absence of the video signal at the external input terminal. A video signal is detected by the video signal detection unit when the switching circuit is set to a side that selects an external input of an external input terminal, and a signal detection unit and a control unit that controls switching of the switching circuit. Provided is a video signal switching device which maintains the set state when it is detected and automatically switches the switching circuit to the reception video signal side when no video signal is detected.

[0005]

The presence or absence of the video signal is detected by detecting the sync signal of the video signal. Then, when the video signal detection unit corresponding to the selected external input terminal detects the video signal, the control unit maintains the setting of the external input terminal, and when the video signal is not detected, switches to the reception video signal side. When the video signal is not detected, the fact is displayed on the screen.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A video signal switching device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an essential part showing an embodiment of a video signal switching device when one external input terminal is used according to the present invention, and FIG. 2 is a video signal switching device when three external input terminals are used. In FIG. 1, 1 is a receiving circuit that outputs a video signal S1 (received video signal) related to the received signal,
V1 is an externally input video signal, 2 is a switching circuit for switching between the received video signal S1 and the external input video signal V1, 3 is a video signal detection unit, 4 is a control unit for performing switching control of the switching circuit 2, 5
Is an on-screen display unit. In addition, in FIG.
The same parts as those in FIG. 1 are designated by the same reference numerals, 21 is a switching circuit, 22
Reference numerals 24 to 24 denote a first video signal detection section, a second video signal detection section, and a third video signal detection section corresponding to each external input terminal, and 25 denotes a control section.

Next, the operation of the present invention will be described in the order of FIG. 1 and FIG. In FIG. 1, the switching circuit 2 receives a received video signal S1 and an external input video signal V1. The switching of the switching circuit 2 is performed by the control unit according to the user's selection. In addition, a video signal detector is provided on the external input line to detect the presence or absence of the external video signal. This detection is performed by detecting the synchronizing signal of the video signal. Therefore,
When the sync signal is detected, the external video signal V1 exists, and when the sync signal is not detected, the V1 does not exist. The data related to this detection result is sent to the control unit 4. Here, the control unit 4 actually means a microcomputer. Now, when the switching circuit 2 is set to the external input side (V1 side) by the user's selection, the video signal detection unit 3 detects the video signal when the external video signal V1 is actually input. The control unit 4 maintains the current state (V1 side). However, when the external video signal V1 is not input, the video signal is not detected by the video signal detection unit 3.
Then, the control unit 4, which has detected from the data from the video signal detection unit 3 that the external video signal V1 is not input, switches the switching circuit 2 to the reception video signal S1 side. In this case, the control unit 4 further outputs an on-screen display signal to the on-screen display unit 5 to display a predetermined display in order to inform the user that the external video signal V1 is not input.

Next, FIG. 2 will be described. FIG. 2 shows an embodiment in which the basic technique shown in FIG. 1 is applied to multiple input terminals. FIG. 2 shows an example in which the external input terminals are three terminals V1 to V3, and an image detection circuit (22 to 24) is provided for each terminal to detect the presence or absence of an image signal on each input line. The data related to the detection result is sent to the control unit 25 as in FIG. Now, Figure 1
Similarly, when the switching circuit 21 is set to the position for selecting the second external video signal V2 in accordance with the user's setting, the V2
Is detected by the second video signal detection circuit 23, the current setting position (V2 position) is maintained, but when V2 is not detected, the reception video signal S1 side is switched. Control unit 4
Recognizes the set position of the switching circuit 21 from the switching signal output by itself. Even when the switching circuit 21 is switched to another line of V2 or V3, the same operation as in the case of V1 described above is performed.

[0009]

As described above, according to the present invention, 1
In a satellite broadcast receiver or the like provided with one or more external input terminals, if the video signal is not input to the input terminal while the external input terminal side is selected, the received signal is automatically Switch to select and display on screen. Therefore, if no signal is left, the screen is cut off, so that it can be prevented that the receiver is erroneously recognized as a failure. Also, the on-screen display can inform the user that there is no external input. The present invention has particular significance when the previous setting state is forgotten, such as when the power is once turned off and then turned on again after being used on the external input terminal side.

[Brief description of drawings]

FIG. 1 is a block diagram of essential parts of an embodiment of a video signal switching device according to the present invention.

FIG. 2 is a block diagram of a main part of another embodiment of the video signal switching device according to the present invention.

[Explanation of symbols]

 1 receiving circuit 2 switching circuit 3 video signal detecting unit 4 control unit 5 on-screen display unit V1 external input video signal S1 receiving video signal 21 switching circuit 22 first video signal detecting unit 23 second video signal detecting unit 24 third Video signal detection unit 25 Control unit

Claims (3)

[Claims] 1. A switching circuit for switching between a video signal received by a receiving device and a video signal from one external input terminal, a video signal detecting section for detecting the presence or absence of a video signal at the external input terminal, and the switching circuit. When the switching circuit is set to the side for selecting the external input of the external input terminal, the setting state is set when the video signal is detected by the video signal detection section. A video signal switching device, characterized in that the switching circuit is automatically switched to the received video signal side when the video signal is not detected. 2. A switching circuit for switching a received video signal of the receiving device and a video signal from each of two or more external input terminals, and the external input terminal for detecting the presence or absence of the video signal of each of the external input terminals. Each of which is provided with a video signal detection section and a control section which controls switching of the switching circuit, and when the switching circuit is set to a state of selecting any one of external inputs of external input terminals. ,
When the video signal detection unit of the external input terminal detects a video signal, the setting state is maintained, and when the video signal is not detected, the switching circuit is automatically switched to the reception video signal side. Video signal switching device. 3. The video signal switching device according to claim 1, wherein a signal for on-screen display is output when the video signal is not detected by the video signal detection unit.