JPH11355608A - Monitor device and video signal transmitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To emphasize resolution without sense of incongruity by correcting the signal level of a signal for resolution correction in accordance with the signal level of a video signal. SOLUTION: A control circuit 42 controls the gain of a variable gain amplifier circuit 41 in accordance with an output signal of a low-pass filter 43. The circuit 41 amplifies a high pass component extracted from a signal level of an output signal of the filter 43 with set gain by a bandpass filter 2. An amplitude limitation circuit 3 performs amplitude limitation of the amplified high pass component and outputs signal for resolution correction. An adder 4 adds the signal for resolution correction to the original luminance signal Y1. An enhancement circuit 40 varies the signal level of the signal for resolution correction in accordance with the signal level of a luminance signal so as to correspond to nonlinear characteristic of a cathode-ray tube and varies the correction quantity of resolution. That is, the correction quantity of resolution is reduced more at a part, which has a high signal level of a luminance signal and consists of parts where an image is bright, than at a part which has a low signal level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitor device and a video signal transmitting device, and can be applied to, for example, a television receiver. The present invention enhances the resolution of a bright area and a dark area to the same extent by correcting the signal level of a resolution correction signal generated from a video signal in accordance with the signal level of the video signal, thereby providing a resolution-free signal. Be able to emphasize.

[0002]

2. Description of the Related Art Conventionally, television receivers have been designed to enhance the resolution of a display image by enhancing the high frequency components of a luminance signal by an enhance circuit.

FIG. 9 is a block diagram showing an enhancement circuit of this type of television receiver. In the enhancement circuit 1, a band-pass filter (BPF) 2
Converts the high-frequency component corresponding to the resolution to be emphasized into a luminance signal YI.
The amplitude limiting circuit 3 limits the amplitude of the high frequency component and outputs a resolution correction signal.

At this time, the amplitude limiting circuit 3 suppresses a signal component whose amplitude is smaller than the threshold value TH1 around the 0 level and has an amplitude larger than the threshold value TH2, as shown in FIG. The signal component is output with its amplitude limited. Thus, the amplitude limiting circuit 3 removes a signal component having a small amplitude corresponding to a noise component from a high frequency component, and suppresses and outputs a signal component having a large amplitude so as not to excessively enhance the resolution.

[0005] The adder 4 adds the output signal of the amplitude limiting circuit 3 to the original luminance signal YI, thereby obtaining the luminance signal YI.
And outputs a luminance signal YO by emphasizing the high-frequency component of

As a result, the enhancement circuit 1 emphasizes the high-frequency components included in the outline portion of the image, so that, for example, the luminance signal YI shown in FIG. The luminance signal YO in which the outline of the display image is emphasized as described above is output.

[0007]

As shown in FIG. 12, a cathode ray tube used in a television receiver is
It has a nonlinear input / output characteristic in which the light emission luminance level increases exponentially according to the signal level of the luminance signal. Therefore, the higher the signal level, the greater the change in the emission luminance with respect to the change in the luminance signal.

For this reason, when the high frequency component of the luminance signal is enhanced by the enhancement circuit 1 as shown in FIG. 9, a brighter portion is displayed with enhanced resolution. For this reason, in a conventional monitor device or the like, there is a problem in that the resolution is emphasized so as to be different between a bright region and a dark region, and an unnatural image is displayed.

The present invention has been made in view of the above points, and is intended to propose a monitor device capable of enhancing resolution without a sense of incongruity, and a video signal transmitting device for outputting a video signal to a monitor device or the like. is there.

[0010]

According to the present invention, there is provided a monitor apparatus for enhancing the resolution of a video signal by adding a resolution correction signal to the video signal for display. A correction means for correcting the signal level of the resolution correction signal according to the level is provided.

Further, the present invention is applied to a video signal transmitting apparatus for enhancing the resolution of a video signal by adding a resolution correction signal to the video signal and outputting the signal. Is provided.

According to the correcting means for correcting the signal level of the resolution correcting signal in accordance with the signal level of the video signal, the amount of correction of the resolution in accordance with the signal level of the video signal so as to correspond to the non-linear characteristics of a cathode ray tube or the like. Can be varied. As a result, the resolution of the bright region and the resolution of the dark region can be enhanced to the same extent, and the resolution can be enhanced without a sense of discomfort.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(1) First Embodiment FIG. 2 is a block diagram showing a television receiver according to a first embodiment of the present invention. In the television receiver 10, the tuning unit 11 selects a television broadcast signal desired by the user from the output signal of the antenna 12, converts the signal into an intermediate frequency signal, and outputs the signal.

The video receiver 13 demodulates the video signal SV from the intermediate frequency signal, and separates and outputs a luminance signal. That is, in the video receiving unit 13, the video intermediate frequency amplifying circuit 14 amplifies the intermediate frequency signal and outputs the amplified intermediate frequency signal to the video detecting circuit 15 and the audio receiving unit 16. Video detection circuit 15
Detects the intermediate frequency signal and demodulates and outputs the video signal SV.

The first video amplifier circuit 17 amplifies the video signal SV and outputs it to the color signal reproducing section 18 and the synchronous deflecting section 19, and separates the luminance signal Y1 from the video signal SV by, for example, a comb filter. Output.

The second video amplifying circuit 20 outputs the luminance signal Y
The signal quality of the display image is adjusted by correcting the signal level of No. 1. At this time, the second video amplifier circuit 20 outputs the luminance signal Y2 by enhancing the high frequency component of the luminance signal Y1 by the enhance circuit.

On the other hand, the color signal reproducing section 18 separates the chroma signal from the video signal SV and outputs the color difference signals RY, B
Play -Y. That is, the band amplification circuit 22 separates and outputs the chroma signal by band-amplifying and amplifying the video signal SV.

The color demodulation circuit 23 synchronously detects the chroma signal with reference to the burst signal, so that the color difference signal R
-Y and BY are demodulated. The matrix circuit 24 generates a color difference signal GY by performing a matrix operation on the color difference signals RY and BY, and generates the color difference signals RY and B-Y.
Y and GY are output. The color signal output circuit 25 generates color signals R, G, B by performing a matrix operation on the color difference signals RY, BY, GY and the luminance signal Y2, and generates these color signals R. , G, B
Drive.

Further, in the synchronous deflecting unit 19, a synchronous separating circuit 27 separates a synchronous signal from the video signal SV.
The deflection circuit 28 controls the deflection yoke 29 according to the synchronization signal.
Drive. With these, the television receiver 10
An image of a television broadcast signal is displayed.

In the audio receiving section 16, an audio intermediate frequency amplification circuit 30 extracts a signal in an audio band from the intermediate frequency signal and amplifies it. The FM detection circuit 31 demodulates the audio signal SA by detecting the intermediate frequency signal output from the audio intermediate frequency amplification circuit 30. The audio amplifier circuit 32 reproduces the audio of the television broadcast signal by amplifying the audio signal SA and driving the speaker 33.

(1-1) Enhancement Circuit FIG. 1 is a block diagram showing the enhancement circuit. In the enhance circuit 40, the same components as those of the enhance circuit 1 described above with reference to FIG. 9 are denoted by the corresponding reference numerals, and duplicate description will be omitted.

The enhancement circuit 40 amplifies the high-frequency component of the luminance signal Y 1 extracted by the band-pass filter 2 by the variable gain amplifying circuit 41 and limits the amplitude by the amplitude limiting circuit 3. The resolution is emphasized by adding to the signal Y1. At this time, the enhancement circuit 40
By controlling the gain of the variable gain amplifying circuit 41 by the control circuit 42, the signal level of the resolution correction signal is changed to change the resolution correction amount.

That is, in the enhancement circuit 40, a low-pass filter (LPF) 43 extracts a low-frequency component of the luminance signal Y1, thereby removing a noise component from the luminance signal Y1 and outputting the same.

The control circuit 42 controls the low-pass filter 4
3 controls the gain of the variable gain amplifying circuit 41 according to the output signal. That is, in the control circuit 42, the comparator 44 compares the signal level of the output signal of the low-pass filter 43 with the threshold value THA and outputs a comparison result.

The selection circuit 45 includes a control signal output circuit (α)
The first and second control signals output from 46 and (β) 47 are input to first and second selection input terminals, respectively,
The first or second control signal is selected and output according to the comparison result of the comparator 44. Here, the first control signal is
The second control signal is a control signal for setting the gain of the variable gain amplifier circuit 41 to a predetermined gain α, and the second control signal is a control signal for setting the gain of the variable gain amplifier circuit 41 to a smaller gain β than the gain α. is there.

As shown in FIG. 3, the control circuit 42 adjusts the signal level of the input signal of the comparator 44 to a threshold value THA.
If smaller, the first control signal is output from the selection circuit 45 to set the gain of the variable gain amplifier 41 to the gain α. On the other hand, when the signal level of the input signal of the comparator 44 is larger than the threshold value THA, the second control signal is output from the selection circuit 45 to reduce the gain of the variable gain amplification circuit 41 to a gain β smaller than the gain α. Set to.

The variable gain amplifying circuit 41 amplifies the high-frequency component extracted by the band-pass filter 2 with the gain set as described above. The amplitude limiting circuit 3 limits the amplitude of the amplified high frequency component and outputs a signal for resolution correction. The adder 4 adds the resolution correction signal to the original luminance signal Y1. Thereby, the enhancement circuit 40 varies the signal level of the resolution correction signal according to the signal level of the luminance signal so as to correspond to the nonlinear characteristic of the cathode ray tube 26, and varies the correction amount of the resolution. In other words, the correction amount of the resolution is reduced in a high signal level portion of the luminance signal, which is a bright portion of the image, as compared with a low portion.

Further, in this embodiment, the control circuit 42 varies the threshold value THA in response to the operation of the operation member arranged on the control panel 48.

In the above configuration, in the television receiver 10 (FIG. 2), a television broadcast signal desired by the user is selected by the tuning section 11 and converted into an intermediate frequency signal. The video signal SV of the intermediate frequency signal is demodulated in the video receiving unit 13, and the color signals R, B, and G are demodulated from the video signal SV in the color signal reproducing unit 18 and displayed.

At this time, the luminance signal Y 1 is extracted from the video signal SV by the first video amplification circuit 17, and is output through the enhancement circuit 40 of the second video amplification circuit 20. That is, in the enhancement circuit 40 of the second video amplification circuit 20 (FIG. 1), the resolution correction signal output from the amplitude limiting circuit 3 is added to the luminance signal Y1 by the adder 4 to emphasize the resolution. That is, in the luminance signal Y1, after a high-frequency component corresponding to the resolution to be emphasized is extracted by the band-pass filter 2, the amplitude is limited by the amplitude limiting circuit 3 via the variable gain amplifying circuit 41, and the original luminance is added by the adder 4. It is added to the signal Y1. Thus, the high-frequency component of the luminance signal Y1 is enhanced according to the signal level added to the luminance signal Y1, and the resolution is enhanced.

At this time, the luminance signal Y1 is input to the control circuit 42 via the low-pass filter 43,
4, the signal level of the luminance signal Y1 becomes the threshold value TH.
The first control signal or the second control signal is selected by the selection circuit 45 according to the comparison result, and is output to the variable gain amplifier 41. Thereby, the signal level of the resolution correction signal is corrected according to the signal level of the luminance signal Y1, and the correction amount of the resolution is changed.

That is, the high-frequency component extracted by the band-pass filter 2 is set by the first control signal in the variable gain amplifier circuit 41 when the signal level of the luminance signal Y1 is small with reference to the threshold value THA. Gain α
When the signal level of the luminance signal Y1 is high, the gain β is smaller than the gain α set by the second control signal.
Amplified by

As a result, the enhancement circuit 40 responds to the luminance signal Y1 shown in FIG.
As shown in (B), the luminance signal Y2 is output by reducing the correction amount of the resolution of the portion where the signal level is high as compared with the portion where the signal level is low.

As a result, the cathode ray tube 26 has an input / output characteristic in which the emission luminance increases exponentially according to the signal level.
In the above, the outline of the dark part formed by the low signal level and the outline of the bright part formed by the high signal level are displayed with the same emphasis, so that the light area and the dark area are equal. The resolution can be emphasized, and the resolution can be emphasized without discomfort.

At this time, by operating the control panel 48 to vary the threshold value THA, it is possible to adjust the degree of correcting the resolution according to the user's preference. Thereby, a desired image quality can be obtained.

According to the above arrangement, the signal level of the resolution correction signal generated from the luminance signal is varied according to the signal level of the luminance signal, so that the resolution of the bright region and the resolution of the dark region are enhanced to the same extent. As a result, the resolution can be enhanced without discomfort.

(2) Second Embodiment FIG. 5 is a block diagram showing an enhancement circuit of a television receiver according to a second embodiment. In this television receiver, the enhancement circuit 50 is applied to a television receiver configured to process a video signal by digital signal processing instead of the enhancement circuit 40 of FIG. In this embodiment, the same components as those in the first embodiment are denoted by the corresponding reference numerals, and the duplicate description will be omitted.

This enhancement circuit 50 varies the amount of resolution correction by the same characteristics as the gamma correction processing of a video signal. That is, the enhancement circuit 50 outputs the luminance signal DY composed of the digital signal extracted by the band-pass filter 2.
Is multiplied by the multiplier 51 and the amplitude is limited by the amplitude limiting circuit 3, and then added to the original luminance signal DY by the adder 4 to enhance the resolution. At this time, the enhancement circuit 5
In the case of 0, the coefficient of the multiplier 51 is controlled by the control circuit 52, thereby correcting the signal level of the resolution correction signal and changing the correction amount of the resolution.

The control circuit 52 controls the coefficient of the multiplier 51 according to the signal level of the luminance signal DY output from the low-pass filter 43. That is, the control circuit 52 has a read-only memory (ROM) storing a plurality of coefficient data.
The coefficient of the multiplier 51 is set by outputting the corresponding coefficient data using the output signal of the low-pass filter 43 as an address.

The multiplier 51 multiplies the high-frequency component extracted by the band-pass filter 43 with the set coefficient. The amplitude limiting circuit 3 limits the amplitude of the multiplied high frequency component and outputs a resolution correction signal. The adder 4 adds the resolution correction signal to the original luminance signal DY to add a luminance signal D
Y1 is output.

At this time, as shown in FIG. 6, when the signal level of the output signal of the low-pass filter 43 increases, the control circuit 52 decreases the coefficient of the multiplier 51 along the curve L. Here, when the adder 4 adds the resolution correction signal to the original luminance signal DY, the curve L indicates that the component of the resolution correction signal in the luminance signal DY1 after the addition is as shown in FIG. This is a characteristic in which the coefficient of the multiplier 51 is set so that the change amount decreases as the signal level increases in accordance with the gamma correction characteristic of the video signal.

Thus, the enhancement circuit 50 corrects the signal level of the resolution correction signal in accordance with the signal level of the luminance signal DY with the characteristic corresponding to the gamma correction processing for correcting the non-linear characteristic of the cathode ray tube 26 to correct the resolution. Vary the amount. As a result, in this embodiment, the resolution can be enhanced to the same extent in a bright area and a dark area, and the resolution can be enhanced without a sense of incongruity.

According to the above configuration, the signal level for the resolution correction signal generated from the luminance signal is corrected by the characteristic corresponding to the gamma correction processing according to the signal level of the luminance signal, whereby the first embodiment is performed. The resolution can be emphasized without a sense of discomfort compared to the form.

(3) Other Embodiments In the first embodiment described above, the case where the correction amount of the resolution is varied with reference to the threshold value THA of 1 has been described. However, the present invention is not limited thereto, and the correction amount of the resolution may be changed based on a plurality of threshold values. In this way, the resolution can be enhanced without a sense of discomfort.

In the first embodiment described above,
Although the case where the threshold value THA is changed in response to the operation of the operation member arranged on the control panel has been described, the present invention is not limited to this. For example, the ratio of the gain α and β or the gain α and β itself can be changed. May be. By doing so, the image quality can be adjusted more finely.

In the above-described second embodiment,
Although the case where the correction amount of the resolution is varied by the characteristic corresponding to the gamma correction processing has been described, the present invention is not limited to this, and the correction is performed so as to correspond to the characteristic obtained by approximating the characteristic of the gamma correction with a polygonal line as shown in FIG. The amount may be variable. This makes it possible to easily set the coefficient data.

In the above-described second embodiment,
Although the case where the coefficient of the multiplier is varied by the fixed-value coefficient data stored in the control circuit has been described, the present invention is not limited to this, and the correction amount is adjusted according to the user's preference similarly to the first embodiment. You may be able to. In this case, it is conceivable that a multiplier is separately added to change the coefficient of the multiplier in response to the operation of the operation element arranged on the control panel.

Further, in the above-described embodiment, the case where the resolution is enhanced by enhancing the high frequency component has been described. However, the present invention is not limited to this, and the signal component obtained by differentiating the luminance signal is added to the resolution. Can be widely applied when emphasizing, for example.

In the above-described embodiment, the case where the resolution is enhanced by signal processing of the luminance signal has been described. However, the present invention is not limited to this. Can also be widely applied.

Further, in the above embodiment, the case where the present invention is applied to a television receiver has been described. However, the present invention is not limited to this, and is applicable to a monitor device such as a liquid crystal display device and various monitor devices. The present invention can be widely applied to video signal transmission devices such as video tape recorders and video cameras that output video signals.

[0052]

As described above, according to the present invention, the resolution of a bright region and a dark region can be improved by correcting the signal level of a resolution correction signal generated from a video signal according to the signal level of the video signal. It is possible to emphasize the resolution by emphasizing them to the same degree without discomfort.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a television receiver using the enhancement circuit of FIG. 1;

FIG. 3 is a characteristic curve diagram showing input / output characteristics of the control circuit of FIG.

FIG. 4 is a signal waveform diagram for explaining enhancement of resolution by the enhancement circuit of FIG. 1;

FIG. 5 is a block diagram illustrating an enhancement circuit according to a second embodiment;

FIG. 6 is a characteristic curve diagram showing input / output characteristics of the control circuit of FIG.

FIG. 7 is a characteristic curve diagram showing gamma correction characteristics of a cathode ray tube.

FIG. 8 is a characteristic curve diagram for explaining resolution correction according to another embodiment.

FIG. 9 is a block diagram showing a conventional enhancement circuit.

FIG. 10 is a characteristic curve diagram showing input / output characteristics of the amplitude limiting circuit of FIG. 9;

11 is a signal waveform diagram for explaining the enhancement of resolution by the enhancement circuit of FIG. 9;

FIG. 12 is a characteristic curve diagram showing input / output characteristics of a cathode ray tube.

[Explanation of symbols]

1, 40, 50 ... enhancement circuit, 2 ... band-pass filter, 3 ... amplitude limiting circuit, 4 ... adder, 10 ...
... Television receiver, 26 ... Cathode tube, 41 ... Variable gain amplifier circuit, 42, 52 ... Control circuit, 43 ... Low pass filter, 44 ... Comparator, 45 ... Selection circuit, 46, 47 ... Control signal output circuit, 48 ... Control panel, 51 ... Multiplier

Claims (10)

[Claims] 1. A monitor device for emphasizing and displaying the resolution of the video signal by adding a resolution correction signal to a video signal, wherein the signal generation means generates the resolution correction signal from the video signal. A monitor device comprising: an adding unit that adds a resolution correction signal to the video signal; and a correction unit that corrects a signal level of the resolution correction signal in accordance with a signal level of the video signal. 2. The amplifying means for amplifying the resolution correcting signal; a low-pass filter for extracting a low-frequency component of the video signal; and a signal level of an output signal output from the low-pass filter. 2. The monitor device according to claim 1, further comprising control means for changing a gain of said amplification means. 3. The control unit includes: a comparing unit that compares a signal level of an output signal output from the low-pass filter with a predetermined threshold to output a comparison result; and outputs a control signal according to the comparison result. The monitor device according to claim 2, further comprising a selection unit configured to select and output, wherein a gain of the amplification unit is changed by the control signal. 4. The correction means includes: a multiplication means for multiplying the resolution correction signal; a low-pass filter for extracting a low-frequency component of the video signal; and a signal level of an output signal output from the low-pass filter. 2. The monitor device according to claim 1, further comprising control means for changing a coefficient of said multiplication means. 5. The control means includes coefficient data output means for outputting coefficient data according to a signal level of an output signal output from the low-pass filter, and varies a coefficient of the multiplication means by the coefficient data. The monitor device according to claim 4, wherein: 6. A video signal transmitting device for enhancing a resolution of the video signal by adding a resolution correction signal to a video signal and outputting the video signal, wherein a signal generation unit configured to generate the resolution correction signal from the video signal. Video signal transmission, comprising: an adding unit that adds the resolution correction signal to the video signal; and a correction unit that corrects the signal level of the resolution correction signal according to the signal level of the video signal. apparatus. 7. The amplifying means for amplifying the resolution correcting signal; a low-pass filter for extracting a low-frequency component of the video signal; and a signal level of an output signal output from the low-pass filter. 7. The video signal transmitting apparatus according to claim 6, further comprising control means for changing a gain of said amplifying means. 8. The control unit, comprising: a comparing unit that compares a signal level of an output signal output from the low-pass filter with a predetermined threshold and outputs a comparison result; and outputs a control signal according to the comparison result. 8. The video signal transmitting device according to claim 7, further comprising a selection unit for selecting and outputting, wherein the gain of the amplification unit is varied by the control signal. 9. The correction means includes: a multiplication means for multiplying the resolution correction signal; a low-pass filter for extracting a low-frequency component of the video signal; and a signal level of an output signal output from the low-pass filter. 7. The video signal transmitting apparatus according to claim 6, further comprising control means for changing a coefficient of said multiplying means. 10. The control means has coefficient data output means for outputting coefficient data according to a signal level of an output signal output from the low-pass filter, and varies a coefficient of the multiplication means by the coefficient data. 10. The video signal transmitting device according to claim 9, wherein: