JPH099210A - Television receiver - Google Patents

Abstract

PURPOSE: To eliminate the change of average luminance at the time of suppressing the amplitude level of interpolation signal so as to dissolve the degradation of the visibility of a moving part by switching the setting value of a picture quality adjustment circuit in linking with the time of switching the amplitude level of an amplitude control circuit by a control circuit. CONSTITUTION: The lightness of luminance signal and contrast, etc., are adjusted in the picture quality adjustment circuit 10 and the setting value of the picture adjustment circuit 10 is also switched in linking with the time of switching the amplitude suppression level of the amplitude control circuit 4 by the control circuit 9. Thus, when the amplitude of the interpolation signal is suppressed, the change of the average luminance of the entire screen is reduced and incompatibility at the time of changeover is reduced. That is, since the average luminance of the entire screen is lowered when the amplitude level of the interpolation signal is lowered in the circuit 4, by raising the amplitude level of the entire luminance signal inversely in the circuit 10, the average luminance is prevented from being changed from the one before the changeover.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver which interpolates an image signal of interlaced scanning and converts it into a progressive scanning system for display.

[0002]

2. Description of the Related Art NTS is a television broadcasting system.
There are various methods such as C, PAL, SECAM,
In either method, an interlaced scanning method is used in which every other screen is scanned in order to narrow the transmission band as much as possible while maintaining high image quality.

However, with the recent increase in the screen size of television receivers, scanning lines are noticeable in interlaced scanning and the roughness of the screen becomes noticeable. Therefore, so-called clear vision in which interlaced scanning is converted into progressive scanning and displayed. A receiver is being developed.

In the clear vision receiver, a motion adaptive interpolation signal processing circuit using a frame memory and a line memory for double speed conversion are used for double speed conversion of an image signal for sequential scanning. As a result, the details of the moving part become unclear, and there is a problem in that the image is lacking in clearness as compared with the conventional interlaced scanning type television receiver.

Therefore, a method described below has been proposed as a method for eliminating this blurring (Japanese Patent Laid-Open No. Hei 4 (1998) -19984).
-95479 gazette). FIG. 6 is a block diagram of the conventional clear-vision television receiver described above.

In FIG. 6, reference numeral 1 is an A / D converter for inputting an NTSC composite video signal and converting it into a digital signal, and 2 is for separating the digitized composite video signal into a luminance signal and a chrominance signal. YC separation circuit, 3 is an interpolation signal processing circuit that produces a scanning line interpolation signal from the luminance signal separated by the YC separation circuit using a field memory, etc. 4 is an amplitude control circuit that suppresses the amplitude of the output of the interpolation signal processing circuit 3. Is.

Further, 5 and 6 are line memories for double speed conversion, 7 is a selection circuit for alternately selecting the outputs of the double speed conversion memories 5, 6 at a frequency twice the horizontal scanning frequency of the input signal, and 8 is selected. D that converts the output of the circuit 7 into an analog signal
A / A converter, 9 is a control circuit for controlling the amplitude suppression level of the amplitude control circuit 4, 10 is an image quality adjusting circuit, and 11 is a display device such as a CRT.

The operation of the television receiver configured as described above will be described below. First, the interpolation signal processing circuit 3 uses a motion detection circuit that determines whether a pixel is a still image or a moving image, and a field memory that uses a field memory to calculate an interpolation signal from pixels of scanning lines at the same vertical position in the preceding and following fields. It is composed of an interpolating processing circuit and a field interpolating processing circuit that uses a line memory to calculate an interpolation signal from pixels of upper and lower scanning lines in the same field. Interpolation processing is performed on the still image portion due to the strong correlation in the time direction, and field interpolation processing is performed on the moving image portion due to the weak correlation in the time direction to form the interpolation signal.

In the double speed conversion memories 5 and 6, the A / D
The luminance signal and the interpolated luminance signal are written at the sampling frequency of the converter 1 and read at a frequency twice the sampling frequency, thereby double-converting each signal. Then, the selection circuit 7 alternately selects the outputs of the double-speed conversion line memories 5 and 6 at a frequency that is twice the horizontal scanning frequency, thereby sequentially performing scanning.

The above is the normal clear vision processing, but in the conventional example shown in FIG. 6, the amplitude control circuit 4 for suppressing the amplitude of the output of the interpolation signal processing circuit 3 is provided, and the brightness level of the interpolation signal is set to the actual scanning line. By lowering it a little, the problem of clear vision type television receiver, which is the problem of clearness of moving parts, is solved. In addition, the control circuit 9
Since the amplitude suppression level of the amplitude control circuit 4 can be switched by, the amplitude suppression level can be switched according to the user's preference.

[0011]

However, the conventional example has the following problems. That is, when watching a normal broadcast, it is preferable to suppress the amplitude of the interpolated signal because the sharpness is increased, but the optimum value of the level of the interpolated signal varies depending on the contents of the broadcast and the environment around the television. It is possible to come. For example, on a graphic screen with no motion such as a character broadcast, it may be better to suppress the interpolation signal so that the scanning lines will not be noticeable, and even if it is a regular broadcast, the interpolation signal will be the same for a still image-centered program with little motion. It would be better not to repress too much.

Further, when the surroundings of the television receiver are bright, the interpolation signal is suppressed and the scanning lines are not so much noticeable to the eyes, but when the surroundings are dark, the flicker is noticeable when the scanning lines are visible. Therefore, it is better not to suppress the interpolated signal because it will tire the eyes.

As described above, the suppression level of the interpolated signal varies depending on various conditions. In the conventional example, however, the user must switch the level of the interpolated signal in order to achieve the optimum state. I won't. Further, if the level of the interpolation signal is changed, the brightness of the entire screen also changes, so that the user needs to redo image quality adjustment such as contrast.

In view of the above problems, the present invention provides a television receiver capable of automatically obtaining the optimum image quality by reducing the user's operations for obtaining the optimum image quality as much as possible.

[0015]

In order to solve the above problems, the television receiver of the present invention automatically sets the image quality adjusting circuit at the same time as switching the suppression level of the amplitude control circuit of the interpolation signal by the control circuit. Change so that the overall brightness level does not change.

Further, in a television receiver having a teletext reception function, the amplitude suppression level is automatically switched between the teletext reception and the normal broadcast reception, and each is automatically optimized.

Further, a circuit for discriminating whether the screen has many still images, moving images, or many moving images is provided, and the amplitude suppression level is automatically switched according to the ratio of the still images and the moving images, and each is automatically optimized. .

Further, a circuit for discriminating the frequency characteristic of the image is provided, the amplitude suppression level is automatically switched according to the frequency characteristic of the image, and each is automatically optimized.

Further, an optical sensor for detecting the ambient brightness of the television receiver is provided, and the amplitude suppression level of the interpolation signal is automatically set to an optimum value according to the ambient brightness.

[0020]

The present invention has the above-mentioned configuration,
Even if the environment around the television changes, the user can enjoy the program with optimum image quality without doing anything.

[0021]

【Example】

(Embodiment 1) First, a television receiver according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a television receiver according to the first embodiment of the present invention. In FIG. 1, 1 to 9 are the same as those in the conventional example of FIG. 6, 10 is an image quality adjusting circuit, and 11 is a display device such as a CRT.

The operation of the television receiver of the first embodiment of the present invention constructed as above will be described below.

The present embodiment is also the same in that the output amplitude of the interpolation signal processing circuit 3 is suppressed by the amplitude control circuit 4. Further, the control circuit 9 switches the amplitude suppression level in the same manner, but this embodiment is different in that the control circuit 9 controls the amplitude control circuit 4 and the image quality adjustment circuit 10 at the same time.

The image quality adjusting circuit 10 adjusts the brightness and contrast of the brightness signal, but when the control circuit 9 switches the amplitude suppression level of the amplitude control circuit 4, the set value of the image quality adjusting circuit 10 is also switched. Thus, even if the amplitude of the interpolation signal is suppressed, the change in the average luminance of the entire screen is reduced, and the discomfort when switching is reduced. That is, when the amplitude control circuit 4 lowers the amplitude level of the interpolation signal, the average luminance of the entire screen is lowered.
By raising the amplitude level of the entire luminance signal in the image quality adjusting circuit 10, the average luminance does not change from that before switching.

As described above, according to the present embodiment, the change in average luminance that occurs when the amplitude level of the interpolation signal is suppressed in order to eliminate the reduction in the clearness of the moving portion is eliminated, and a clear image is easily obtained. It is possible to obtain

(Second Embodiment) Next, a television receiver according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram of a television receiver according to the second embodiment of the present invention. 1 in FIG.
9 is the same as the conventional example of FIG. 6, 12 is a tuner circuit for selecting a television broadcasting station, 13 is a teletext receiving circuit for demodulating teletext, and 14 is a selection circuit for switching between teletext and normal broadcast. .

The operation of the television receiver of the second embodiment of the present invention constructed as above will be described below. The present invention is also the same in that the output amplitude of the interpolation signal processing circuit 3 is suppressed by the amplitude control circuit 4. Further, the control circuit 9 switches the amplitude suppression level in the same manner, but the television receiver of the present invention is characterized in that the teletext receiving circuit 13 is provided.

In the teletext, the display of letters and graphic images is the main focus. In addition, since there is no moving image but only a still image, the problem of blurring due to clear vision processing does not occur, and by doubling the speed, a very beautiful image can be provided. Therefore,
It is not necessary to suppress the amplitude level of the interpolation signal, and if it is suppressed, the sharpness will be lost.

Therefore, in the present embodiment, when the teletext receiving circuit 13 is selected by the control circuit 9, the amplitude control circuit 4
Switch automatically so that the amplitude level is not suppressed with.

As described above, according to the present embodiment, when the teletext is received, the suppression of the amplitude level of the interpolation signal is automatically stopped, and a double image is obtained to obtain a clean image with a large scanning line density. be able to.

(Embodiment 3) Next, a third embodiment of the present invention, a television receiver for kicking Nio, will be described with reference to the drawings. FIG. 3 is a block diagram of a television receiver according to the third embodiment of the present invention. 1 in FIG.
11 are the same as those in the first embodiment of FIG. 1, and 15 is a still image / moving image discrimination circuit.

The operation of the television receiver according to the third embodiment of the present invention constructed as above will be described below. The present invention is also the same in that the output amplitude of the interpolation signal processing circuit 3 is suppressed by the amplitude control circuit 4.

Although the control circuit 9 switches the amplitude suppression level in the same manner, the television receiver according to the present embodiment has each pixel detected by the motion detection circuit in the interpolation signal processing circuit 3. A still image / moving image discriminating circuit 15 for discriminating the degree of movement of the entire screen based on the movement data is provided, and the degree of movement of the screen is given to the control circuit 9 as data. Based on the motion data of the screen, the control circuit 9 increases the amplitude level suppression amount of the amplitude control circuit 4 as the motion data increases, and decreases the amplitude level suppression amount of the amplitude control circuit 4 when the motion data is small. The amplitude level suppression amount is switched in conjunction with the degree of movement.

Further, since the image quality adjusting circuit 10 is also switched in association with the amplitude control of the interpolation signal, the brightness of the screen does not change even if the amplitude level of the interpolation signal is switched according to the degree of movement of the screen. .

As described above, according to the present embodiment, when the screen movement is small, the original image quality of clear vision is utilized without reducing the amplitude level of the interpolation signal, and when the screen movement is large, the amplitude level of the interpolation signal is reduced. Therefore, it is possible to prevent deterioration of sharpness and always obtain an optimum image quality.

(Fourth Embodiment) Next, a television receiver according to a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a block diagram of a television receiver according to the fourth embodiment of the present invention. In FIG.
1 to 11 are the same as those in the first embodiment of FIG. 1, and 16 is a frequency characteristic discriminating circuit for discriminating the frequency characteristic of the image.

The operation of the television receiver according to the fourth embodiment of the present invention constructed as above will be described below. The present invention is also the same in that the output amplitude of the interpolation signal processing circuit 3 is suppressed by the amplitude control circuit 4.

The same applies to the case where the control circuit 9 switches the level of amplitude suppression. However, the television receiver of the present invention performs Fourier transform processing on an image signal to obtain a frequency spectrum, thereby obtaining the frequency of the image. A frequency characteristic discrimination circuit 16 for analyzing characteristics is provided, and when the analysis result shows that the image contains many high frequency components, the amplitude level suppression amount of the amplitude control circuit 4 is set large, and the image does not contain many high frequency components. At times, the amplitude level suppression amount of the amplitude control circuit 4 is reduced.

In this way, when a fine image is being received, the image becomes clear by suppressing the amplitude level of the interpolation signal, and it does not contain much high frequency components, for example, in programs such as weather forecasts and animations. Since the amplitude level of the interpolation signal is not suppressed so much, the scanning lines become inconspicuous, and the optimum image quality can be obtained for each.

Further optimization can be performed by using the discrimination by the still picture / moving picture discrimination circuit in the third embodiment together.

(Fifth Embodiment) Next, a television receiver according to a fifth embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a block diagram of a television receiver according to the fifth embodiment of the present invention. In FIG. 5, 1
1 to 11 are the same as those in the first embodiment of FIG. 1, and 17 is an optical sensor circuit for discriminating the brightness around the television receiver.

The operation of the television receiver of the fifth embodiment of the present invention constructed as above will be described below. The present invention is also the same in that the output amplitude of the interpolation signal processing circuit 3 is suppressed by the amplitude control circuit 4.

The television receiver of the present invention detects the brightness of the surroundings by the optical sensor circuit 17 although the control circuit 9 switches the amplitude suppression level, and the amplitude control is performed when the surroundings are bright. The circuit 4 suppresses the amplitude level of the interpolation signal, and at the same time, the image quality adjusting circuit 10 increases the signal amplitude to improve the clearness.

When the surroundings are dark, the amplitude control circuit 4
The suppression of the amplitude level of the interpolated signal due to the above is stopped, and at the same time, the amplitude of the signal is lowered by the image quality adjustment circuit 10 to obtain a moist image quality so that the viewer's eyes are not tired.

As described above, according to the present invention, since the amplitude level of the interpolated signal and the amplitude level of the entire signal are changed depending on the ambient brightness, the optimum image quality is automatically set according to the viewing situation. Is possible. Further optimization can be performed by using the still image / moving image discriminating circuit of the third embodiment and the frequency characteristic discriminating circuit of the fourth embodiment together.

[0046]

As described above, according to the present invention, the amplitude level of the interpolation signal of the clear vision processing circuit is suppressed and the setting of the image quality adjustment circuit is changed at the same time. Further, when the signal is a character broadcast, the suppression of the interpolation signal is stopped. Or, by determining the still image / moving image of the image signal, the frequency characteristic, or the ambient brightness, it is possible to automatically obtain the optimum image quality in that situation. Can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a television receiver according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a television receiver according to a second embodiment of the present invention.

FIG. 3 is a block diagram of a television receiver according to a third embodiment of the present invention.

FIG. 4 is a block diagram of a television receiver according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram of a television receiver according to a fifth embodiment of the present invention.

FIG. 6 is a block diagram of a conventional television receiver.

[Explanation of symbols]

 1 A / D converter 2 YC separation circuit 3 Interpolation signal processing circuit 4 Amplitude control circuit 5, 6 Double speed conversion line memory 7 Selection circuit 8 D / A converter 9 Control circuit 10 Image quality adjustment circuit 11 Display device 12 Tuner circuit 13 Teletext receiving circuit 14 Selection circuit 15 Still image / moving image discrimination circuit 16 Frequency characteristic discrimination circuit 17 Optical sensor circuit

Claims (5)

[Claims] 1. An interpolation signal processing circuit for generating a scanning line interpolation signal from an interlaced scanning image signal converted into a digital signal, an amplitude control circuit for controlling the amplitude of an output signal of the interpolation signal processing circuit, and the image signal. Is written at the sampling frequency and is read at a frequency twice the sampling frequency, and the interpolation signal whose amplitude is controlled by the amplitude control circuit is written at the sampling frequency, and the interpolation signal is written at the frequency twice the sampling frequency. The second memory circuit to be read, the signal read from the first memory circuit and the signal read from the second memory circuit are alternated at a frequency twice the horizontal scanning frequency of the input image signal. And a D / A converter for converting the double-speed image signal output from the selection circuit into a double-speed image signal. An A converter, an image quality adjustment circuit that adjusts the image quality by adjusting the amplitude of the D / A converted double speed image signal, and the like, and the amplitude control of the amplitude control circuit and the image quality adjustment of the image quality adjustment circuit are performed together. A television receiver including a control circuit. 2. A television receiver having a teletext receiving function, comprising an interpolation signal processing circuit for generating a scanning line interpolation signal from an interlaced scanning image signal converted into a digital signal, and the interpolation signal processing circuit. An amplitude control circuit for controlling the amplitude of the output signal, a first memory circuit in which the image signal is written at a sampling frequency and read at a frequency twice the sampling frequency, and an interpolation signal amplitude-controlled by the amplitude control circuit. Is written at a sampling frequency and is read at a frequency twice the sampling frequency, a signal read from the first memory circuit and a signal read from the second memory circuit. And a selection circuit for alternately selecting the image signal at a frequency twice the horizontal scanning frequency of the input image signal to make the image signal a double-speed image signal, A D / A converter for D / A converting the double speed image signal output from the selection circuit, and a control circuit for controlling the amplitude of the amplitude control circuit are provided. A television receiver, wherein the amplitude control amount of the amplitude control circuit is automatically switched depending on time. 3. An interpolation signal processing circuit for producing a scanning line interpolation signal from an interlaced scanning image signal converted into a digital signal, an amplitude control circuit for controlling the amplitude of an output signal of the interpolation signal processing circuit, and the image signal. Is written at the sampling frequency and is read at a frequency twice the sampling frequency, and the interpolation signal whose amplitude is controlled by the amplitude control circuit is written at the sampling frequency, and the interpolation signal is written at the frequency twice the sampling frequency. The second memory circuit to be read, the signal read from the first memory circuit and the signal read from the second memory circuit are alternated at a frequency twice the horizontal scanning frequency of the input image signal. And a D / A converter for converting the double-speed image signal output from the selection circuit into a double-speed image signal. An A converter, an image quality adjustment circuit that adjusts the image quality by adjusting the amplitude of the D / A converted double speed image signal, and a still image / moving image determination circuit that determines whether the screen is a still image or a moving image. And the amplitude control of the amplitude control circuit and the image quality adjustment of the image quality adjustment circuit for the still image /
A television receiver comprising: a control circuit which is interlocked with the moving image discrimination circuit based on the discrimination result. 4. An interpolation signal processing circuit for generating a scanning line interpolation signal from an interlaced scanning image signal converted into a digital signal, an amplitude control circuit for controlling an amplitude of an output signal of the interpolation signal processing circuit, and the image signal. Is written at the sampling frequency and is read at a frequency twice the sampling frequency, and the interpolation signal whose amplitude is controlled by the amplitude control circuit is written at the sampling frequency, and the interpolation signal is written at the frequency twice the sampling frequency. The second memory circuit to be read, the signal read from the first memory circuit and the signal read from the second memory circuit are alternated at a frequency twice the horizontal scanning frequency of the input image signal. And a D / A converter for converting the double-speed image signal output from the selection circuit into a double-speed image signal. An A converter, an image quality adjustment circuit for adjusting the image quality by adjusting the amplitude of the D / A converted double speed image signal, a frequency characteristic determination circuit for determining the frequency characteristic of the input image signal, and the amplitude control circuit. A television receiver comprising: a control circuit that performs amplitude control and image quality adjustment of the image quality adjustment circuit in conjunction with each other based on a determination result of the frequency characteristic determination circuit. 5. A television receiver provided with an optical sensor circuit for detecting ambient brightness, comprising an interpolation signal processing circuit for producing a scanning line interpolation signal from an interlaced scanning image signal converted into a digital signal, An amplitude control circuit for controlling the amplitude of the output signal of the interpolation signal processing circuit, a first memory circuit in which the image signal is written at a sampling frequency and read at a frequency twice the sampling frequency, and the amplitude control circuit. A second memory circuit in which an amplitude-controlled interpolation signal is written at a sampling frequency and read at a frequency twice the sampling frequency, a signal read from the first memory circuit, and the second memory circuit The read signal is alternately selected at a frequency twice the horizontal scanning frequency of the input image signal, and the image signal is set as the double speed image signal. A selection circuit, and a D / A converter for D / A converting the double speed image signal output from the selection circuit,
An image quality adjustment circuit that adjusts the image quality by adjusting the amplitude of the D / A converted double speed image signal, and the amplitude control of the amplitude control circuit and the image quality adjustment of the image quality adjustment circuit based on the detection result of the optical sensor circuit. A television receiver having a control circuit for interlocking with each other.