JPH01218274A - Television receiver - Google Patents

Abstract

PURPOSE:To prevent a picture which makes a user feel incongruous and uncomfortable from being displayed by displaying the picture before switching stored in a picture memory when the picture is switched. CONSTITUTION:When the picture is switched, for example, when a channel is switched, a television is made into a still picture displaying mode, and picture data at the time of the switching of the channel are stored based on a control signal from a microcomputer 4. The picture data are read from a picture memory 15, and displayed on a cathode-ray tube 14 as the still picture. During this time, a station selecting action to lead in the television signal of the switched different channel is executed. When the station selection is completed, the still picture displaying mode is canceled, and the moving picture of a new channel is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a television receiver, and more particularly to a television receiver having an image memory.

[Summary of the invention]

In the present invention, when switching images, the image stored in the image memory of the television receiver before switching is displayed.

Therefore, at the time of image switching, a still image at the time of image switching is displayed instead of a distorted image due to synchronization flow or a pitch-black image with blanking, so that the user can enjoy a more pleasant feeling of use.

[Conventional technology]

In conventional television receivers, when images are switched, a distorted image is displayed due to synchronization flow, causing discomfort to the user.

Therefore, in recent television receivers, in order to prevent the above-mentioned distorted image from being displayed when switching images,
Blanking is applied to images and muting is applied to audio until the acquisition of television signals is completed.

In this specification, "when switching images" means when switching channels in a television signal, or when switching input sources (television signal and video signal from an external video device).

[Problem that the invention seeks to solve]

As mentioned above, by blanking the image and minifying the audio until the television signal acquisition is complete, the display of distorted images, audio, etc. can be completely eliminated. There is still a problem in that blanking causes the screen to become completely black for a moment, which still gives the user a sense of discomfort and discomfort.

By the way, Japanese Patent Laid-Open No. 62-10980 discloses that in an in-vehicle television, when the reception level drops below a predetermined value, the image information of the previous field is displayed as a still image, thereby preventing a distorted image from being displayed. The technology has been disclosed.

Although this conventional technology can deal with fluctuations in the reception level of television signals, there is no mention of the image disturbance that occurs when switching images as described above, and it is difficult to improve this problem. It was wanted.

Therefore, an object of the present invention is to provide a television receiver that does not display images that give the user a sense of discomfort or discomfort, such as distorted images or blanked images, when switching images. be.

[Means for solving problems]

In the present invention, a television receiver having an image memory is configured to display the image stored in the image memory before switching when switching images.

[Effect]

When switching images, for example, when switching channels, the still image display mode is set. Then, image data at the time of channel switching is stored in the image memory based on a control signal from the microcomputer. This image data is then read out and displayed as a still image on a cathode ray tube. During this time, a channel selection operation is being performed to draw in the television signal of another channel that has been switched. Then, when the channel selection is completed, the above-mentioned still image display mode is canceled,
Video images of the new channel will be displayed.

In this way, when switching images, the still image held in memory at the time of switching is displayed, so
Images that give the user a sense of discomfort or discomfort are not displayed, and the user can enjoy a comfortable range of use.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a television receiver having an input terminal for an external video signal as shown in FIGS. 1 and 3. Note that this explanation will be made in the following order.

(A) Regarding the configuration and circuit operation of a television receiver (B) Regarding still image display when switching images (A) Regarding the configuration and circuit operation of a television receiver Figure 1 shows a television reception to which this invention is applied. This shows the configuration of the machine. In FIG. 1, a received signal from an antenna 1 is supplied to a tuner circuit 2. In FIG. A television signal of a desired channel is selected by the tuner circuit 2, and this television signal is converted into a video intermediate frequency signal by a mixing circuit of the tuner circuit 2.

This television receiver uses a PLL synthesizer type channel selection circuit, and when selecting a channel, AFT
control is in place.

The above-mentioned PLL synthesizer one-type channel selection circuit has the following configuration and operation.

The PLL circuit 3 shown in FIG. 1 is composed of a prefrequency divider, a frequency divider, a phase comparator, a reference signal oscillator, and a low-pass filter (all of which are not shown). and,
A local oscillation signal from the tuner circuit 2 is supplied to a phase comparator via a prescaler and a frequency divider. On the other hand, the reference signal oscillator supplies the reference signal to the phase comparator.The 0-phase comparator supplies the local oscillation signal via the prescaler and the frequency divider, and the reference signal oscillator outputs the reference signal. A reference signal is compared, and this comparison output is supplied to the tuner circuit 2 via a low-pass filter, and the local oscillation signal is controlled based on this comparison output.

When selecting a channel for the first time, AFT control is performed. That is, the frequency division ratio of the frequency divider is set so that when the local oscillation frequency is a regular carrier frequency, it becomes close to the corresponding frequency. This frequency division ratio is set and supplied by the microcomputer 4 based on channel data held in advance. Then, the local oscillation frequency is moved upward and downward in steps, that is, AFT control is performed. When a television signal is pulled in by AFT control, offset channel data based on the frequency division ratio at that time is stored. At the next tuning, the offset channel data stored during this first tuning is used to select the desired channel. selected.

By the way, various commands such as a channel switching command and a source switching command are given to the above-mentioned microcomputer 4 from the key switch 5 and the remote control transmitter 6 via a light receiving section (not shown). When a channel switching command is given to the microcomputer 4, the frequency division ratio of the frequency divider of the PLL circuit 3 is reset to correspond to the desired channel. Further, when a source switching command is given to the micro combinator 4, the first switch circuit 7 is switched according to the specified input source.

The video intermediate frequency signal output from the tuner circuit 2 is supplied to an intermediate frequency signal processing circuit 8. In this intermediate frequency signal processing circuit 8, the video intermediate frequency signal is amplified and video detected, and a composite color video signal is output. This composite color video signal is supplied to the first switch circuit 7.

In FIG. 1, 9 is an input terminal for an external video signal. External video equipment such as a VTR or a video disc can be connected to this external video signal input terminal 9. A composite color video signal from an external video device connected to this input terminal 9 is supplied to the first switch circuit 7.

In the first switch circuit 7, the input source is switched by a control signal outputted from the microcomputer 4 based on a source switching command from the remote control transmitter 6 or the key switch 5. That is, the first switch circuit 7 selects one of the composite color video signal from the intermediate frequency signal processing circuit 8 and the composite color video signal from the input terminal 9.

The composite color video signal output from the first switch circuit 7 is supplied to a Y/C separation circuit 10.

The Y/C separation circuit 10 separates the selected composite color video signal into Y/C, and separates the selected composite color video signal into a luminance signal Y, a color difference signal R-Y,
B-Y, and the luminance signal Y and color difference signal R-Y
, B-Y are output to the A/D conversion circuit 11 and the second switch circuit 12, respectively.

In a state where image switching is not performed, the second switch circuit 1
2, the luminance signal Y supplied from the Y/C separation circuit 10
The nine color difference signals R-Y, B-Y are demodulated into three primary color signals R, G, and B by the video signal processing circuit 13, and the three primary color signals R
, G, and B are supplied to the cathode ray tube 14, and an image is displayed.

On the other hand, the A/D conversion circuit 11 performs A/D conversion on the luminance signal Y9 and the color difference signals RY and B-Y supplied from the Y/C separation circuit 10, respectively. This A/D converted image data is sequentially written to addresses in the memory 15 designated by the controller 16. Note that this memory 15 is
It is also used when performing picture-in-picture based on commands from the remote control transmitter 6 or the key switch 5.

Then, from the remote control transmitter 6 or the key switch 6,
When a channel switching command or a source switching command for switching channels of a television signal is input to the microcomputer 4, a control signal is output from the microcomputer 4 to the controller 16.

The controller 16 controls input/output of image data in the memory 15 and switching of the second switch circuit 12 based on control signals from the microcomputer 4. The controller 16 then stops writing the image data to the memory 15 based on the input control signal. As a result, image data for the last frame is stored in the memory 15.

The controller 16 reads this image data and
The A conversion circuit 17 performs D/A conversion to reproduce the luminance signal Y9 color difference R-Y, B-Y, and the second switch circuit 12
supply to. The controller 16 also outputs a switch switching signal to the second switch circuit 12, and the luminance signal Y9 color difference signals R-Y, B-Y, etc. from the D/A conversion circuit 17 are supplied to the video signal processing circuit 13. do it like this.

The luminance signal Y9 color differences R-Y, B-Y are demodulated as three primary color signals R, G, B by the video signal processing circuit 13,
The still image is supplied to the cathode ray tube 14 and displayed.

Then, the switching operation is performed while the image data in the memory 15 is read out and displayed on the cathode ray tube 14 as a still image. For example, in the case of a television signal, this switching operation involves switching the frequency of a new channel to the PL.
It is locked by the L circuit 3 and a new television signal is drawn in. Also, when changing the input source of the composite color video signal, it is necessary to switch between a television signal and a video signal from an external video device. This results in a distorted image due to the flow of synchronization.

Alternatively, a pitch-black image with blanking is not displayed, and a comfortable usability can be provided to the user.

Further, this operation is performed by the software of the microcomputer 4 that controls the memory 15, so the burden on the software is small and it can be realized without increasing costs.

Incidentally, in order to perform so-called picture-in-picture, in which another image is displayed within one image, the first switch circuit 7. Another system such as the Y/C separation circuit 10 is required.

By the way, in the above-described embodiment, writing of image data to the memory 15 is stopped at the time of image switching. The image data at that time is held and read out, so-called frozen, and a still image is displayed on the cathode ray tube 14, but the present invention is not limited to this. For example, at the time of image switching, the microcomputer 4 issues a command to capture image data for one frame, and based on this command, the controller 16 writes image data for one frame at the time of image switching to the memory 15. A still image may be displayed on the cathode ray tube 14 by reading out the image data.

Further, in the above embodiment, the second switch circuit 12 controls the video signal [luminance signal Y] from the Y/C separation circuit 10.
Although the nine-color color difference R-Y, B-Y) and the video signal from the D/A conversion circuit 17 are switched, the present invention is not limited to this (for example, as shown in FIG. /
The A conversion circuit 17 may be connected to the video signal processing circuit 13. That is, when the control signal from the microcomputer 4 is input to the controller 16, writing of image data to the memory 15 is stopped, and the image data in the memory 15 is read out and D/A converted. Along with this, the controller 16 and the video signal processing circuit 13
A control signal is issued to perform blanking.

The above-mentioned D
/A-converted image data is superimposed on the cathode ray tube 14.
It is also possible to display a still image.

Note that the other configurations and operations in FIG. 2 are the same as those in the above-described embodiment, so common parts are designated by the same reference numerals in the figure, and redundant explanation will be omitted.

(B) Still image display when switching images The procedure for displaying still images when switching images is shown in the flowchart of FIG.

First, it is checked whether a channel switching command has been input from the remote control transmitter 6 or the key switch 5 (step 2). In addition to this, the remote control transmitter 6
Alternatively, it is checked whether a source switching command has been input from the key switch 5 (step 2).

When the above-mentioned switching command is input, the still image display mode is set, and after the image switching, writing of image data to the memory l5 is stopped, the image data at the time of image switching is read out, and the still image is displayed on the cathode ray tube 14. Display (step ■).

Next, a switching operation is performed (step ■).

That is, this switching operation is for displaying a new video signal image on the cathode ray tube 14. For example,
In the case of a television signal, this means locking the frequency of a new channel using a PLL and pulling in the television signal, and in the case of changing the input source, combining the television signal and the video signal from the external video equipment. It's about switching.

In step (2), it is checked whether the above-mentioned switching operation has been completed. If the switching operation has been completed, the above-described still image display mode on the cathode ray tube 14 is canceled and the process returns to step. CRT 1 in this case
4 changes from a still image of image data held in the memory 15 to a moving image of a new composite color video signal.

〔Effect of the invention〕

According to this invention, at the time of image switching, a still image at the time of image switching is displayed instead of a conventional image distorted by synchronized flow or a blanked black image, etc. This has the effect of eliminating the discomfort and discomfort experienced by users, and providing the user with a comfortable feeling of use.

Further, according to the embodiment, it is possible to freeze and display an image at the time of image switching by simply changing the software of the microcomputer that controls the image memory, and the burden on the software is also light. Also,
External installation requires no circuitry and only requires software changes, so it has the advantage of being able to be implemented without increasing costs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of necessary parts for explaining an example in which the second switch circuit shown in the configuration of FIG. 1 is not provided, and FIG. is a flowchart used to explain one embodiment of the present invention. Explanation of main symbols in the drawings 2: Tuner circuit, 4: Microcomputer, 15
:memory. Agent Patent Attorney Masatoshi Sugiura

Claims (1)

[Scope of Claims] A television receiver having an image memory, characterized in that when an image is switched, the image stored in the image memory before the switching is displayed. .