JPH05236381A - Television receiver - Google Patents

Abstract

PURPOSE:To provide the television receiver whose muting time is adjusted according to the time required to acquire synchronism at the time of channel switching. CONSTITUTION:In the television receiver equipped with a MUSE/NTSC converter 8 and a video muting circuit 13, a microcomputer 9 commands the start of video muting operation to the video muting circuit 13 in response to the channel switching operation and then commands the end of the video muting operation to the video muting circuit 13 in response to the completion of the synchronism acquiring operation of a video circuit 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention converts a high-definition signal such as a MUSE signal into an NTSC signal for CRT.
The present invention relates to a television receiver that can be screen-displayed on a television, etc.

[0002]

2. Description of the Related Art In recent years, high-definition broadcasting using broadcasting satellites has been put to practical use, and a special receiver that forms one screen with twice as many scanning lines as a conventional television receiver,
It is possible to watch high-definition broadcasting on a high-definition screen. MUSE (Multiple Sub-NyquistS) is a video transmission system for high-definition broadcasting using broadcasting satellites.
ampling Encode) method is being developed.

In such a situation, the MUSE signal is changed to the NTSC signal in response to the demand to watch the high-definition broadcast using the current television receiver which is already popular in general households, regardless of the special receiver for high-definition television. MUSE / NTSC converters have been developed (for example, magazine "TV Technology", October 1989, pages 40 to 45). According to the MUSE / NTSC converter, a high-definition signal received by a BS tuner is converted into an NTSC signal, and this signal is supplied to a video input terminal of a television receiver, so that the current NTSC signal can be obtained.
Not only broadcast programs, but also high-definition broadcast programs 1
Can be viewed on a single receiver.

In a conventional television receiver equipped with a MUSE / NTSC converter, when a channel to be displayed on the screen is switched from one channel to another channel by operating a channel such as a remote controller, that is, , NTSC broadcasting when switching from one terrestrial wave to another terrestrial wave, when switching from terrestrial wave to output of external video equipment such as VTR, or when switching from terrestrial wave to MUSE broadcasting wave, synchronization signal of signals before and after switching It is inevitable that there will be discontinuities and discontinuities. Therefore, the image is disturbed when the channel is switched, and the viewer feels uncomfortable. In order to avoid this, conventionally, a video mute circuit is provided, and when switching channels, video mute processing is performed to darken the screen for a fixed time set by a counter or the like.

[0005]

In the MUSE system, as is well known, the sync pull-in operation of the video circuit is performed on the basis of both the horizontal sync pulse and the vertical sync pulse, and therefore, compared with the NTSC system based only on the horizontal sync pulse. It takes a long time to synchronize. Therefore, in order to realize a complete video mute at any channel switching, it is necessary to set a long video mute time in accordance with the switching from NTSC broadcasting to MUSE broadcasting.

However, as a result, when the NTSC broadcast is switched from one terrestrial wave to another terrestrial wave, an unnecessarily long video mute time is set, and the screen switching is delayed. , Give viewers anxiety.

An object of the present invention is to provide a television receiver in which the video mute time is adjusted according to the time required for synchronization pull-in at the time of channel switching.

[0008]

A television receiver according to the present invention comprises a high-definition / NTSC conversion means for converting a high-definition signal into an NTSC signal, and a video circuit for performing processing such as color demodulation on the NTSC signal for output. 12), a video mute circuit (13) for setting the whole screen to a single color display regardless of the presence or absence of a video signal from the video circuit (12), and a video mute circuit (13) for video switching in response to a channel switching operation. Means for instructing the start of mute operation, means for detecting the completion of the sync pull-in operation of the video circuit (12) after channel switching, and the video mute circuit (13) ending the video mute operation in response to the detection. And means for commanding.

[0009]

[Function] Whether the channel is switched from ground wave to ground wave, from ground wave to external video equipment, or from ground wave to satellite broadcast wave, the period from the start to the end of the synchronization pull-in operation accompanying the change. , Video mute circuit
(13) operates to put video mute on the display screen and prevent temporary screen disturbance.

[0010]

According to the television receiver of the present invention, since the video mute time is automatically adjusted according to the time required for the synchronization pull-in at the time of channel switching, the screen is always switched with the shortest video mute time. It is possible to realize a good viewing environment.

[0011]

The examples are for the purpose of illustrating the present invention and should not be construed as limiting the invention or limiting the scope of the invention.

An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the NTSC system VHF signal or UHF signal applied to the U / V antenna (1) is selected by the U / V tuner (2) after channel 1 is selected, and then the detector (3 ), And a color TV signal is extracted. The TV signal is supplied to the input terminal a of the first changeover switch (10). Also, external video equipment input terminal (4)
Is connected to the input terminal b of the first changeover switch (10).

On the other hand, high definition radio waves are BS antennas.
After being received at (5) and converted to an intermediate frequency of 1.2 GHz, it is input to the BS tuner (6) and FM detection is performed. The FM detection output is supplied as the MUSE signal to the input terminal a of the second changeover switch (11), and at the same time, the MUS signal is output.
It is supplied to the E / NTSC converter (8). In addition, MUS
The construction of the E / NTSC converter (8) is well known (see, for example, the magazine "TV Technology", October 1989, No. 40).
Page to page 45), and the description is omitted.

The NTSC signal output from the MUSE / NTSC converter (8) is supplied to the input terminal b of the second changeover switch (11), and the output terminal of the switch (11) is the first changeover switch (10). ) Input terminal c. First
The output terminal of the changeover switch (10) is connected to the CRT (14) via the video circuit (12) and the video mute circuit (13).

The video circuit (12) is composed of a color demodulation circuit, a color synchronization circuit, etc., as is well known, and receives the input TV signal as an R signal.
The signal is supplied to the CRT (14) as a GB signal, and at the time when the synchronous pull-in operation at the time of channel switching is completed, a signal indicating the state is output to the microcomputer (9).

The operations of the U / V tuner (2), the BS tuner (6), the first and second changeover switches (10) and (11), and the video mute circuit (13) are controlled by the microcomputer (9). Has been done. Various operation signals from a remote controller (not shown) and signals for completion of synchronization pull-in obtained from the video circuit (12) are input to the microcomputer (9).

In the above television receiver, the switching operation of the first and second changeover switches (10) and (11) is controlled by the microcomputer (9) as described below to set various modes. That is, set the second changeover switch (11) to
In the state where it is switched to the side, when the first selector switch (10) is switched to the side a, the terrestrial wave reception mode, the side b is switched to the external video equipment mode, and the side c is switched to the satellite broadcasting (MU).
SE signal) reception mode is set. Also, the second switch
With the (11) switched to the b side, set the first switch (10) to c
When switched to the side, a mode in which the MUSE system is converted to the NTSC system and projected is set.

Next, the control operation of the video mute circuit (13) by the microcomputer (9) will be described with reference to FIG. First, the presence or absence of a channel switching operation is judged (15), and when there is a switching operation, the microcomputer commands the video mute circuit (16) to start the video mute.

Next, the microcomputer waits for the signal input of the sync pull-in completion from the video circuit after switching the first and second changeover switches as described above according to the mode selected by the viewer (17). Then, the video mute operation is continued until there is the input.

When a signal for completion of synchronization pull-in is input from the video circuit, the microcomputer instructs the video mute circuit to end the video mute operation.
(18) Do it. As a result, the video mute time is automatically adjusted according to the time required for pulling in the synchronization when the channel is switched.

The operation relating to the determination of the synchronization pull-in completion by the video circuit is performed as follows, for example. N
In the case of the TSC method, first, the video circuit synchronously separates the input signal to create a horizontal sync pulse. Also, a horizontal blanking pulse is created based on the flyback pulse input. Next, the above-mentioned operation is repeated until the horizontal synchronizing pulse and the horizontal blanking pulse coincide with each other, and when the coincidence is obtained, it is judged that the synchronization is established, and the signal showing the completion of the synchronization pull-in is sent to the microcomputer.

On the other hand, in the case of the MUSE system, the video circuit creates a horizontal synchronizing pulse and a vertical synchronizing pulse from the input signal and also creates a horizontal blanking pulse and a vertical blanking pulse based on the flyback pulse input. Next, the above operation is repeated until the horizontal sync pulse and the horizontal blanking pulse match and the vertical sync pulse and the vertical blanking pulse match. Then, when the above-mentioned coincidence is obtained, the transmission signal is fetched and the frame pulse is extracted from it. When this frame pulse is obtained eight times in the correct format, it is judged that the synchronization has been established for the first time, and the signal indicating the completion of the synchronization pull-in is sent to the microcomputer.

In the above television receiver, according to the time required for the synchronization pull-in at the time of channel switching,
Since the video mute time is variably set, temporary disturbance of the screen is prevented and at the same time, the shortest video mute is always performed.
The screen can be switched quickly in a short time, and a good viewing environment can be provided to the viewer.

Since the variable setting of the video mute time is realized only by the software of the microcomputer shown in FIG. 2, the hardware has exactly the same configuration as the conventional device as shown in FIG. 1, and a new circuit is required. It has excellent effects such as no need to equip additional equipment.

The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or limiting the scope. The configuration of each part of the present invention is not limited to the above embodiment, and it is needless to say that various modifications can be made within the technical scope described in the claims.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a television receiver according to the present invention.

FIG. 2 is a flowchart showing the operation of a microcomputer.

[Explanation of symbols]

 (8) MUSE / NTSC converter (9) Microcomputer (12) Video circuit (13) Video mute circuit

Claims (1)

[Claims] 1. A high-definition / NTSC conversion means for converting a high-definition signal into an NTSC signal, and a video circuit (12) for performing processing such as color demodulation on the NTSC signal and outputting the signal.
It has a video mute circuit (13) that sets the entire screen to a monochromatic display regardless of the presence or absence of a video signal from the video circuit (12), and the NTSC signal and high definition obtained by receiving the NTSC broadcast wave by channel switching In a television receiver capable of switching and displaying an NTSC signal obtained by converting the signal, means for instructing the video mute circuit (13) to start the video mute operation in response to a channel switching operation. A means for detecting the completion of the sync pull-in operation of the video circuit (12) after the channel switching and a means for instructing the video mute circuit (13) to end the video mute operation in response to the detection. Television receiver characterized by.