JP3086460B2 - Television receiver - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver, and more particularly to a television receiver that can set the sharpness of a displayed image to an optimum value for each screen.

[Summary of the Invention] The television receiver of the present invention samples at least one information signal from each area of one screen by sampling a signal within a predetermined area of an input video signal, Image information is obtained from the sampled image data for one screen and data corresponding to, for example, an AGC voltage indicating the electric field strength, and a control signal is set by calculating the image information and the adjustment data.

Then, the sharpness of the screen is adjusted based on the control signal.

Therefore, the optimal sharpness control is always performed based on the state of the screen of the input video signal, and the image quality can be improved.

[Prior Art] As one of adjusting means for improving the image quality of a television receiver, the sharpness of an image is improved by adding a preshoot and an overshoot to a signal waveform.
Sharpness control means are known.

 FIG. 5 shows an example of this sharpness adjustment circuit.

In this circuit, a coil L video signal supplied through the transistor Q, to give a second derivative waveform by emphasizing the high frequency by the capacitor C _1, a terminal of the secondary differential waveform variable resistor VR To enhance the edge of the video signal supplied to the terminal b.

In such sharpness adjustment means, the variable resistor VR
By moving to the a terminal side, sharp image quality can be obtained, and by moving to c terminal side, soft image quality can be obtained. Therefore, the user can adjust the sharpness as desired.

[Problems to be Solved by the Invention] However, since the sharpness control as described above is generally maintained at the sharpness level after being adjusted once, the image quality may deteriorate when the image content changes. Was.

In the following, this point will be explained. In general, sharpness is increased on a bright screen to improve the sharpness of the image, and on a dark screen or when the electric field strength (reception radio wave level) is low,
It is said that the sharpness should be reduced because the preshoot and overshoot of the video signal are conspicuous as noise. In other words, since the appropriate (preferred by the user) sharpness level varies depending on the brightness of the screen content, it is possible to set a certain adjustment level by operating a variable resistor, for example, as in the past. There was a problem that the best video screen could not always be projected if possible.

[Means for Solving the Problems] The present invention has been made in view of such problems, and one screen of a video signal supplied from a TV tuner or a VTR device and input to a video signal processing circuit is provided. Are stored in the storage means, which are set in advance with respect to the sampling means for sampling the information signal in accordance with timing such that the information signal is divided into predetermined areas, the received charge intensity information, and the sampled image data for one screen. And an arithmetic unit that can perform various arithmetic processes based on the adjustment data (or the arithmetic coefficient) selected from the adjusted data group and output a control signal. In the sharpness adjustment circuit of
An object of the present invention is to provide a television receiver in which sharpness control is performed based on a supplied sharpness control signal.

[Operation] The degree of sharpness of the video signal is controlled by image information for each screen obtained from the sampled image data and a control signal determined based on the electric field strength of the received video signal. The optimum adjustment level in the sharpness adjustment circuit is automatically set for each screen based on the video content.

FIG. 1 is a block diagram showing an outline of the present invention.

In this figure, reference numeral 10 denotes a TV tuner, 11 denotes an intermediate frequency amplifying unit, receives and amplifies a TV broadcast, and the amplified composite video signal is input to a video signal processing unit 12 via a switch Sw and processed, and R , G, and B video signals are supplied to the CRT display device 13. Also, for example, VT
The R input terminal T is connected, and the VTR reproduction signal can be supplied to the video signal processing unit 12 in the same manner.

Reference numerals 14A and 14B denote sampling circuits. The sampling circuit 14A samples a video luminance signal (Y signal) supplied to the video signal processing unit 12 from a single screen at a predetermined timing, so that it is displayed on the CRT display device 13. Is obtained and supplied to the arithmetic processing unit 16 described later.

Further, in order to obtain information on the received radio wave level (electric field strength), the sampling circuit 14B also samples the AGC voltage at a predetermined timing.

As the sampling timing, as shown in FIG. 2, for example, voltage values at n positions (Sp points) are sampled in one frame. Then, the image information of one screen can be detected corresponding to the n regions by the n sampling points.

In other words, in other words, information of one point is sampled as a representative value from each area on the divided screen.

If more precise screen information is desired, the number of samplings may be increased, but the optimum number of samplings in one screen may be set in consideration of the processing speed after sampling and the like.

15A and 15B are A / D conversion circuits for converting the signals output from the sampling circuits 14A and 14B into digital signals, and 16 is an arithmetic processing unit by a microcomputer, and the A / D conversion circuit 15
The arithmetic processing is performed based on image data and electric field strength data supplied as digital signals from A and 15B to obtain a control signal for performing optimal sharpness control.

Reference numeral 17 denotes a memory (ROM) in which adjustment data (or an operation coefficient for obtaining the adjustment data) selected by the operation result in the operation processing unit 16 is stored in advance. It is a rewritable memory (RAM) that can also set and store various adjustment data.

19 is a D / A converter circuit for converting the control signal set by the processing unit 16 into an analog signal, the control signal S _s which is an analog signal is supplied to the sharpness adjustment circuit 12A. And the sharpness adjustment circuit 12A
Will be carried out indirectly or directly Sharpness adjustment had not a group to the control signal S _s in.

Reference numeral 20 denotes a manual operation unit that allows the user to manually adjust the brightness level. The output signal from the manual operation unit 20 is directly transmitted to the sharpness adjustment circuit 12A.
May be supplied.

An example of the adjustment value setting operation for each screen in this embodiment, that is, an example of the operation of the arithmetic processing unit 16 will be described with reference to the flowchart of FIG.

When the sampling data of the luminance signal obtained by the sampling circuit 14A is supplied via the A / D conversion circuit 15A, the processing on the sampling data is performed. In this case, as described above, n pieces of sampling data are obtained in one screen, and when the n pieces of sampling data are subjected to A / D conversion and input, processing such as data aggregation is performed, and Obtain the information of the above "brightness" level. Similarly, by processing the AGC voltage data supplied from the sampling circuit 14B, information on the received radio wave level is obtained (10
0).

Then, as shown in steps 101 to 105, a control signal is set so as to obtain the optimal sharpness according to the “brightness” on the screen and the received radio wave level.

That is, lower the sharpness (10
2) If the received signal level is low even on a bright screen, lower the sharpness (104). If the received signal level is high on a bright screen, increase the sharpness according to the degree of brightness (105). Perform processing.

As a specific control signal setting operation, a reference value (constant) of brightness obtained by summing up sampling values for one screen of the Y signal or performing various arithmetic processing is similarly used. On the basis of the value (constant) obtained from the AGC voltage, for example, the control data is determined by reading out the adjustment data using the constant as a parameter from the ROM 17 and performing arithmetic processing of the read-out adjustment data and the constant.

The ROM 17 may store operation coefficients for the respective constant values as table data, and the control signal may be directly obtained from the constants and the values of the constants.

It is also conceivable to store a plurality of adjustment data in the ROM 17 in advance so that the control signal can be set based on the information (constant) obtained from the Y signal and the AGC voltage value.

The provision of the RAM 18 allows a user to write a desired adjustment data group, and also allows a desired sharpness characteristic to be obtained according to preference.

Alternatively, the ROM 17 or the RAM 18 may be configured as a cartridge, and the desired sharpness control may be performed by replacing the cartridge.

Control signal S _s outputted from the arithmetic processing unit 16 is inputted to the sharpness adjustment circuit 12A remains digital data, may adjust the degree of sharpness.

By performing the above-described operation within each vertical synchronization period, a sharpness control signal is output in units of one screen, so that the sharpness of the video signal is adjusted in units of one screen. In the above, an image in an appropriate sharpness state is always output.

In other words, for example, when the received radio wave level is high and the screen is bright, an image (sharp image) is added by a signal to which overshoot and preshoot are added, and when the screen is dark or the received radio wave level is low, the image is formed by a signal having a gradual rise. Sharpness control for providing an image (soft image) is automatically performed.

As a result, it is possible to prevent noise from being noticeable depending on the contents of the screen (in a dark screen or a dark part) and the received radio wave level, and it is possible to obtain a sharper image on a screen where noise is inconspicuous.

Note that the sampling of the luminance signal may be performed, for example, every several screens (several vertical synchronization periods), without being performed for every screen.

Also, the sharpness control can be performed not only during the vertical synchronization period but also during one screen. For example, the control is such that the sharpness of the upper half of the screen is increased and the sharpness of the lower half is decreased. Such control can be easily realized by changing the totalization unit (operation processing unit) of the sampling data described above.

Further, for example, by providing a field memory and sequentially storing sampling data, it is possible to grasp more accurate information on the light and dark position on the screen, the current screen compared with the state of the previous screen, and the like, and to obtain a constant By taking these data into account at the time of setting or at the time of various calculations, more sophisticated sharpness control (for example, adjustment of each area according to the distribution of brightness in one screen) can be achieved. .

Note that the microcomputer described above (the arithmetic processing unit 1)
The operation of obtaining a certain constant from the information signal for one screen input to 6), for example, the luminance signal distribution and the totaling operation, can be easily performed by a circuit as shown in FIG.

In this circuit, the input luminance signal is compared with a preset comparison signal S _c by sequential comparator CP. That is, the comparison signal _Sc has a light / dark threshold level, and is compared with this threshold value. For example, when the input Y signal is at a “bright” level, a voltage value corresponding to the brightness is obtained. Is charged in the capacitor C. This operation is repeated within one vertical synchronization period, and when the vertical synchronization pulse is applied to the transistor T, the voltage value charged in the capacitor C is read and A / D converted to indicate the brightness of the screen. Arithmetic processing unit 16 as a numerical value
Supplied to

[Effects of the Invention] As described above, the television receiver of the present invention sequentially changes the brightness of the input video signal and the screen state displayed based on the electric field strength of the received video signal. Since the sharpness adjustment is performed on a screen-by-screen basis, there is an effect that a screen in the optimum sharpness state can always be displayed.

In particular, it is possible to easily eliminate noise in a dark screen or a weak electric field, to maximize the sharpness of an image in a bright screen, and to achieve a significant improvement in image quality.

Further, since sharpness control is performed by data obtained by sampling a predetermined area of the video signal, for example, a part of the screen is selectively made sharp and the other part is made soft. Advanced image quality adjustment.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is an explanatory diagram of sampling timing, FIG. 3 is a flowchart showing an outline of operation of one embodiment of the present invention, and FIG. Aggregation circuit diagram showing an example of totaling,
FIG. 5 is a circuit diagram showing an example of a conventional sharpness adjustment circuit. 12 is a video signal processing unit, 14A and 14B are sampling circuits, 15
A and 15B are A / D conversion circuits, 16 is an arithmetic processing unit, 17 is ROM, 18 is R
AM and 19 are D / A conversion circuits.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-198483 (JP, A) JP-A-58-97969 (JP, A) JP-A-57-48663 (JP, A) JP-A 62-1984 91083 (JP, A) JP-A-63-164764 (JP, A) JP-A-49-91525 (JP, A) JP-A-61-2477 (JP, A) Japanese Utility Model Laid-Open No. 61-191658 (JP, U) Shokai 63-92469 (JP, U)

Claims (2)

(57) [Claims] 1. A sampling means for sampling an information signal in a predetermined area of a screen corresponding to an input video signal, and outputting sampled image data, and an electric field of a radio wave carrying the input video signal. Electric field intensity detecting means for detecting the intensity, adjustment data storage means in which adjustment data accessible in correspondence with an area to be sampled by the sampling means are stored, the sampled image data, and the electric field strength Computing means for outputting a sharpness control signal for controlling the sharpness of the video screen based on the adjustment data, wherein the computing means is configured to output the sharpness control signal when the screen based on the video signal is brighter than a predetermined brightness, and When the intensity is strong, adjust the video screen to increase the sharpness. Receiver. 2. A field memory means for storing sampling data of the input video signal, wherein the sharpness of the video signal of the entire screen is controlled with reference to the sampling data of the previous screen stored in the field memory means. The television receiver according to claim 1, wherein: