JPH07336614A - Television receiver - Google Patents

Abstract

PURPOSE:To make video and audio outputs stable by suppressing fluctuation in a frequency spectrum in a reception signal in mobile reception. CONSTITUTION:The television receiver having an intermediate frequency amplifier circuits of the separate carrier system each amplifying a video intermediate frequency signal and an audio intermediate frequency signal is provided with a gain control circuit 16 amplifying the audio intermediate frequency at a gain based on a given control signal, and also with a color or audio intermediate frequency circuit 17 to obtain an audio signal within an audible frequency range by detecting the audio intermediate frequency signal amplified by the gain control circuit 16 and to output the audio signal to a next stage, and giving a control signal corresponding to a signal level of the audio intermediate frequency signal to the gain control circuit 16 for controlling the gain, and with an adder 15 to correct a signal level of the intermediate frequency signal by adding the color or the audio intermediate frequency signal amplified by the gain control circuit 16 to the video intermediate frequency signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver used in a mobile state such as a portable liquid crystal television.

[0002]

2. Description of the Related Art A television receiver such as a liquid crystal television set which is used in a moving state has basically the same circuit configuration as that of a television receiver fixedly used. The fluctuation of the frequency spectrum in the received signal in the moving state was not taken into consideration. For this reason, for example, the color and audio signals are unnecessarily amplified in association with the deterioration of the video carrier signal to cause distortion, and the images and audio are largely disturbed, which is often not suitable for use.

[0003]

As described above, the television having the function of stabilizing the image and the sound in consideration of the disturbance of the image and the sound due to the fluctuation of the frequency spectrum in the received signal when used in the moving state. There was no receiver.

The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress the fluctuation of the frequency spectrum in the received signal during mobile reception,
An object of the present invention is to provide a television receiver capable of stabilizing audio.

[0005]

That is, the present invention detects the signal level of an audio intermediate frequency signal in a received intermediate frequency signal, and detects the color or audio intermediate frequency signal in the intermediate frequency signal according to the detection result. This is to correct the signal level.

[0006]

With the above-mentioned structure, it is possible to suppress the fluctuation of the frequency spectrum in the received signal in the mobile reception and stabilize the image and the sound.

[0007]

【Example】

[First Embodiment] A first embodiment of the present invention applied to a color liquid crystal television device will be described below with reference to the drawings.

FIG. 1 shows the basic circuit configuration thereof. Here, it is assumed that a separate carrier type intermediate frequency amplifying circuit for amplifying a video intermediate frequency signal and an audio intermediate frequency signal by separate circuits is used.

In the figure, 11 is an antenna.
The TV radio wave received at 11 is supplied to the tuner 12. The tuner 12 selects a designated channel, converts it into an intermediate frequency signal, amplifies the obtained intermediate frequency signal by an appropriate amplification factor via a preamplifier 13, and then sends it to an intermediate frequency (IF) filter 14.

The intermediate frequency filter 14 separates the video intermediate frequency signal from the color and audio intermediate frequency signals according to the frequency band of the transmitted intermediate frequency signal, and sends the video intermediate frequency signal to the adder 15 for color and Gain control circuit for audio intermediate frequency signals
Output to 16 respectively.

The gain control circuit 16 is an intermediate frequency filter.
The color and audio intermediate frequency signals sent from 14 are amplified by varying the amplification factor so as to have a gain according to a control signal from an audio intermediate frequency circuit 17 which will be described later.
And output to the adder 15.

The audio intermediate frequency circuit 17 changes the voltage value according to the amplified color from the gain control circuit 16 and the signal level of the audio intermediate frequency signal. For example, the control signal such as the AGC signal or the level detection voltage While transmitting to the gain control circuit 16, the color and audio intermediate frequency signals are subjected to voice detection to extract a voice signal, which is further converted into a low frequency signal in the audible range, which is then amplified through the voice amplifier circuit 18, and then amplified by the speaker 19. Let

The adder 15 performs addition calculation of the color and audio intermediate frequency signals from the gain control circuit 16 as a correction signal based on the video intermediate frequency signal from the intermediate frequency filter 14, and the sum signal after correction is added. It is sent to the video intermediate frequency (video IF) circuit 20 as a video intermediate frequency signal.

The video intermediate frequency circuit 20 amplifies the video intermediate frequency signal and performs video detection to obtain a composite video signal, and outputs the composite video signal to the video chroma circuit 21. The video / chroma circuit 21 performs chroma processing on the composite video signal to obtain a chroma signal composed of three primary colors of R, G, and B, and outputs the obtained chroma signal to the A / D conversion circuit 22.

The A / D conversion circuit 22 converts the chroma signal from the video / chroma circuit 21 into digital video data of 3 to 4 bits per pixel and outputs it to the liquid crystal drive circuit 23. The liquid crystal drive circuit 23 sequentially scans and drives the common electrodes of the color LCD panel 24, and at the same time, the A / D conversion circuit 22.
3 to 4 bits of video data given from the device are sequentially read, one line of video data is read, then a gradation signal is created according to the video data, and the same color LCD panel
Display drive of 24 segment electrodes.

In the circuit configuration as described above, the intermediate frequency filter 14 has a frequency characteristic as shown in FIG. 2, and the intermediate frequency signal sent through the preamplifier 13 is converted into a video intermediate frequency signal. , Color and audio intermediate frequency signals. In the figure, fs is an audio signal, fc is a color signal carrier, and fv is a video signal carrier.

Now, when the television receiver is used in a moving state, the frequency spectrum of the signal being received temporarily fluctuates. For example, as shown in FIG. 3, the color and audio intermediate frequency signals become the video intermediate frequency signal. It is assumed that the level is extremely high compared to.

The color and audio intermediate frequency signals separated by the intermediate frequency filter 14 are sent to a gain control circuit 16 where they are amplified with a gain based on a control signal from the audio intermediate frequency circuit 17 and then added. Device 15 and audio intermediate frequency circuit 17
Is output to. When the levels of the color and audio intermediate frequency signals become very high as compared with the video intermediate frequency signal as in this case, the gain control circuit 16 causes the audio intermediate frequency circuit 17
Amplification is performed with a low gain set on the basis of the control signal from.

The color and audio intermediate frequency signals amplified by the low amplification factor are amplified by the speaker 19 through the audio intermediate frequency circuit 17 and the audio amplifier circuit 18, while the adder 15 outputs the intermediate frequency filter 14 Since it is added as a correction signal of the video intermediate frequency signal, the signal level of the video intermediate frequency signal is also increased and is stabilized, and then sent to the video intermediate frequency circuit 20.

FIG. 4 shows the characteristics of the signal obtained by correcting the signal shown in FIG. 3 as a result of the above-mentioned operation. The image intermediate frequency signal and the color and audio intermediate frequency signal are shown. It can be seen that both are well balanced and stabilized.

As described above, for example, when the electric field is equal to or higher than RFAGC (automatic gain control), feedback is applied based on the levels of the color and audio intermediate frequency signals, so that the color and audio intermediate frequency signals and the video intermediate frequency signal are fed. It is possible to realize stable reception in which the signal levels of the respective signals are balanced.

[Second Embodiment] A second embodiment in which the present invention is applied to a color liquid crystal television device will be described below with reference to the drawings.

FIG. 5 shows the basic circuit configuration thereof. Here, it is assumed that an inter-carrier type intermediate frequency amplifying circuit for amplifying a video intermediate frequency signal and an audio intermediate frequency signal by one amplifying circuit is used.

In the figure, 31 is an antenna.
The television wave received at 31 is supplied to the tuner 32. The tuner 32 selects a designated channel, converts it into an intermediate frequency signal, amplifies the obtained intermediate frequency signal with an appropriate amplification factor through a preamplifier 33, and then sends it to an intermediate frequency (IF) filter 34.

The intermediate frequency filter 34 separates the video intermediate frequency signal from the color and audio intermediate frequency signals according to the frequency band in the transmitted intermediate frequency signal, and sends the video intermediate frequency signal to the adder 35 for color and Gain control circuit for audio intermediate frequency signals
Output to 36 respectively.

The gain control circuit 36 is an intermediate frequency filter.
The color and audio intermediate frequency signals sent from 34 are amplified by varying the amplification factor so as to have a gain according to a control signal from an audio intermediate frequency level detection circuit 37 described later, and the adder is added.
Output to 35.

The adder 35 performs addition operation of the color and audio intermediate frequency signals from the gain control circuit 36 as a correction signal based on the video intermediate frequency signal of the intermediate frequency filter 34, and the sum signal is added to the corrected video intermediate frequency signal. Image intermediate frequency (image I
F) Send to circuit 38.

This video intermediate frequency circuit 38 obtains a composite video signal by amplifying and video detecting the video intermediate frequency signal including the color and audio intermediate frequency signals, and outputs this composite video signal to the video chroma circuit 39. On the other hand, the audio intermediate frequency signal is separated, output to the audio intermediate frequency level detection circuit 37, the audio is detected and the audio signal is taken out, and the audio signal is converted to a low frequency signal in the audible range and then the audio signal is amplified. To the circuit 40.

The audio intermediate frequency level detection circuit 37 detects the signal level of the audio intermediate frequency signal sent from the video intermediate frequency circuit 38, and sends a control signal corresponding to the detected level to the gain control circuit 36. Control the amplification factor.

In the audio amplification circuit 40, the speaker 41 is driven to be loud by the signal obtained by amplifying the audio signal from the video intermediate frequency circuit 38, and the sound is emitted. The video / chroma circuit 39 is
Chroma processing is performed on the composite video signal to obtain a chroma signal composed of three primary colors of R, G, and B. The obtained chroma signal is A
Output to the / D conversion circuit 42.

The A / D conversion circuit 42 converts the chroma signal from the video chroma circuit 39 into digital video data of 3 to 4 bits per pixel and outputs it to the liquid crystal drive circuit 43. The liquid crystal drive circuit 43 sequentially scans and drives the common electrodes of the color LCD panel 44, and at the same time, the A / D conversion circuit 42.
3 to 4 bits of video data given from the device are sequentially read, one line of video data is read, then a gradation signal is created according to the video data, and the same color LCD panel
Display drive of 44 segment electrodes.

In the circuit configuration as described above, the intermediate frequency filter 34 has a frequency characteristic as shown in FIG. 6, and the intermediate frequency signal sent through the preamplifier 33 is converted into a video intermediate frequency signal. , Color and audio intermediate frequency signals. In the figure, fs is an audio signal, fc is a color signal carrier, and fv is a video signal carrier.

Now, when the television receiver is used in a moving state, the frequency spectrum of the signal being received temporarily fluctuates. For example, as shown in FIG. 7, the color and audio intermediate frequency signals are changed to the video intermediate frequency signal. It is assumed that the level is extremely high compared to.

The color and audio intermediate frequency signals separated by the intermediate frequency filter 34 are sent to the gain control circuit 36, where they are amplified with a gain based on the control signal from the audio intermediate frequency level detection circuit 37. It is output to the adder 35. When the levels of the color and audio intermediate frequency signals become extremely high as compared with the video intermediate frequency signal as in this case, the audio intermediate frequency level detection circuit 37 detects this,
Based on the control signal, the gain control circuit 36 amplifies with the gain set to be low.

The color and audio intermediate frequency signals amplified by the low amplification factor are added to the video intermediate frequency signal by the adder 35, and the sum output thereof is as shown in FIG. This is a stabilized signal with a level balanced with the audio intermediate frequency signal. This is the video intermediate frequency circuit.
It will be amplified and detected at 38.

In this way, by feeding back the amplification factors of the color and audio intermediate frequency signals based on the detection result of the level of the audio intermediate frequency signal, the signal levels of the color and audio intermediate frequency signals and the video intermediate frequency signal respectively. It is possible to realize balanced and stable reception. Note that only one of the color intermediate frequency signal and the audio intermediate frequency signal may be corrected.

[0037]

As described above in detail, according to the present invention, the signal level of the audio intermediate frequency signal in the received intermediate frequency signal is detected, and the video intermediate frequency signal in the intermediate frequency signal is detected according to the detection result. Since the signal level is corrected, it is possible to provide a television receiver capable of suppressing fluctuations in the frequency spectrum in the received signal during mobile reception and stabilizing images and sounds.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic circuit configuration according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining an operation according to the embodiment.

FIG. 3 is a diagram for explaining the operation according to the embodiment.

FIG. 4 is a view for explaining the operation according to the embodiment.

FIG. 5 is a block diagram showing a basic circuit configuration according to a second embodiment of the present invention.

FIG. 6 is a view for explaining the operation according to the embodiment.

FIG. 7 is a view for explaining the operation according to the embodiment.

FIG. 8 is a diagram for explaining the operation according to the embodiment.

[Explanation of symbols]

11, 31 ... Antenna, 12, 32 ... Tuner, 13, 33 ... Preamplifier, 14, 34 ... Intermediate frequency (IF) filter, 15, 35 ... Adder, 16, 36 ... Gain control circuit, 17 ... Audio intermediate frequency ( Audio IF) circuit, 18, 40 ... Audio amplification circuit, 19, 41 ... Speaker, 20, 38 ... Video intermediate frequency (video IF) circuit, 21, 39 ...
Video chroma circuit, 22, 42 ... A / D conversion circuit, 23, 43
... Liquid crystal drive circuit, 24, 44 ... Color LCD panel, 37 ... Audio intermediate frequency (audio IF) level detection circuit.

Claims (5)

[Claims] 1. A detection means for detecting the signal level of the received audio intermediate frequency signal, and a correction means for correcting the signal level of the color intermediate frequency signal according to the detection result of the detection means. TV receiver. 2. A detection means for detecting the signal level of the received audio intermediate frequency signal, and a correction means for correcting the signal level of the audio intermediate frequency signal according to the detection result of the detection means. TV receiver. 3. A television receiver having a separate carrier type intermediate frequency amplification circuit for amplifying a video intermediate frequency signal and an audio intermediate frequency signal by separate circuits, wherein the audio intermediate frequency is obtained with a gain based on a control signal given. An audio amplifying means for amplifying the signal, and an audio intermediate frequency signal amplified by the audio amplifying means is subjected to audio detection to obtain an audio signal in an audible frequency range and output to the next stage, while the signal level of the audio intermediate frequency signal is outputted. To the audio amplifying means for performing gain control, and the signal level of the color intermediate frequency signal is corrected based on the signal level of the audio intermediate frequency signal amplified by the audio amplifying means. And a correction means for controlling the television receiver. 4. A television receiver having a separate carrier type intermediate frequency amplification circuit for amplifying a video intermediate frequency signal and an audio intermediate frequency signal by separate circuits, wherein the audio intermediate frequency is obtained with a gain based on a control signal given. An audio amplifying means for amplifying the signal, and an audio intermediate frequency signal amplified by the audio amplifying means is subjected to audio detection to obtain an audio signal in an audible frequency range and output to the next stage, while the signal level of the audio intermediate frequency signal is outputted. A voice detecting means for applying a control signal corresponding to the above to the voice amplifying means for gain control, and correcting the signal level of the voice intermediate frequency signal based on the signal level of the voice intermediate frequency signal amplified by the voice amplifying means. And a correction means for controlling the television receiver. 5. A television receiver having an inter-carrier type intermediate frequency amplifier circuit for amplifying an intermediate frequency signal, which is obtained by superimposing a video intermediate frequency signal and an audio intermediate frequency signal, by one amplifier circuit. Detecting means for detecting the signal level of the audio intermediate frequency signal to be produced, and an audio intermediate frequency signal provided in a system different from that of the intermediate frequency signal provided to the amplifier circuit with a gain according to the detection result of the detecting means. And a correcting means for correcting the signal level of the intermediate frequency signal supplied to the amplifier circuit based on the signal level of the audio intermediate frequency signal amplified by the audio amplifying means. Characteristic television receiver.