KR19980053593A - Tint Correction Circuit of Tele Video Equipment - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tint correction circuit of a televideo apparatus capable of eliminating color bleeding on a CRT (Cathode-ray Tube) by correcting distortion of a tint phase generated during video tape playback in a televideo apparatus. A first switching means and a transistor connected in series between the tint adjustment signal input terminal of the IC and a ground; Connected second switching means and resistors, selection means for selecting a TV / video mode, and when the TV mode is selected by the selection means, the second switching means is turned on, and when the video mode is selected, the first switching means. It characterized in that it comprises a processor for turning on the switching means.

Description

Tint Correction Circuit of Tele Video Equipment

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a televideo apparatus, and in particular, a televideo apparatus capable of eliminating color bleeding on a CRT (Cathode-ray Tube) by correcting a distortion of a tint generated during the playback of a video tape. It relates to a tint correction circuit of a device.

1 is a configuration diagram showing the main components of a general televideo apparatus.

In Fig. 1, reference numeral 1 is a reception antenna for receiving a broadcast frequency signal (RF signal), 2 is a tuner for tuning a predetermined broadcast signal from a broadcast frequency signal received through this antenna 1, and 3 is a tuner ( 2) an IF amplifier for amplifying the intermediate frequency signal (IF signal) output from 2) and 4 for detecting a video signal from the IF signal output from the IF amplifier 3 and outputting a composite video signal. Image detector.

In addition, reference numeral 5 is a remote control device for the viewer to operate the televideo device, 6 is a receiving unit for converting the infrared signal applied from the remote control device 5 into an electric code signal, 7 is the remote control device 5 The microprocessor controls the entire device in accordance with the operation signal of the.

In addition, reference numeral 8 is coupled to a color (COL: Color), tint (TLN: Tint), brightness (BRI) and contrast (CON: Contrast) signal output stage of the microprocessor 7 and output from the corresponding output stage. An integrated circuit which generates a predetermined level signal by integrating a pulse width modulated signal (PWM signal).

That is, in general, in the case of the microprocessor 7, since the signal processing is executed digitally, the output signal cannot be generated analogously, and in the case of the chroma IC 9 described later, Analog signals are required as the tint, brightness, and contrast adjustment signals.

Therefore, as described above, the microprocessor 7 outputs a pulse width modulated signal as its output signal, and integrates the pulse width modulated signal into the integrating circuit 8 to generate a predetermined level signal.

Meanwhile, reference numeral 9 in the drawing processes the composite image signal applied by the switching unit 12 to be described later, and outputs the luminance signal (-Y) and the color difference signal (RY, GY, BY) accordingly. It is a chroma IC which executes image signal processing based on the color COL, tint TIN, brightness BRI and contrast CON signals input from one microprocessor 7.

Reference numeral 10 denotes a CRT driver for driving the CRT 11 based on the RGB and luminance signal (-Y) output from the chroma IC 9 described above, and 12 denotes a switching applied from the microprocessor 7. The switching unit selectively outputs an image signal applied from a video part (not shown) and an image signal applied from the image detector 4 according to the signal.

In the above configuration, when the viewer selects the video mode by operating the remote controller 5 to play the video tape while the tele video apparatus is turned on, the microprocessor 7 switches the switching unit 12 to control the switching. The video signal applied from the video part is input to the chroma IC 9.

Then, the microprocessor 7 executes the video playback operation by setting the system controller that controls the video part to the playback mode.

However, in the televideo apparatus having the above-described configuration, if the temperature around the televideo apparatus is installed in a summer or the like is greatly increased, or the video tape is played for a long time by using the televideo apparatus, When the internal temperature of the device rises above a predetermined value, the chroma IC 9 causes thermal runaway.

When the thermal runaway occurs as described above, in particular, the oscillation frequency of the voltage controlled oscillator (VCO) provided inside the chroma IC 9 is changed so that a color phase meter such as tint control has a BY side, that is, a negative voltage. Will turn in the direction.

In addition, the above-described tint phase fluctuation is caused by a defect of the video tape, and when the internal temperature of the televideo apparatus increases, the sagging of the video tape occurs, the signal reproduction cannot be executed correctly and the same phenomenon as the tint phase fluctuation. This will occur.

In addition, when the tint phase is changed in this way, color reproducibility of the image screen output to the CRT 11 is lowered, resulting in deterioration of image quality such as color smearing.

Accordingly, the present invention has been made in consideration of the above-described circumstances, and provides a tint correction circuit of a televideo device which can prevent distortion of the tint phase caused by a temperature rise in or around the video device during video playback. Has its purpose.

1 is a block diagram showing the main configuration of a general televideo device.

2 is a block diagram showing a tint correction circuit of a televideo device according to an embodiment of the present invention.

**** Brief description of the main parts of the drawing ****

1: reception antenna, 5: remote control device,

6: receiver, 7: microprocessor,

8,21: integrating circuit, 9: chroma IC,

10: CRT driving unit, 11: CRT,

12: switching part, Rx: position.

A tint correction circuit of a televideo apparatus according to the present invention for realizing the above object comprises: a first switching means and a transistor connected in series between a tint adjustment signal input terminal of a chroma IC and a ground; And second switching means and resistors connected in series between the tint adjustment signal input terminal and the ground of the chroma IC, selection means for selecting a TV / video mode, and when the TV mode is selected by the selection means. And a processor for turning on the second switching means and turning on the first switching means when the video mode is selected.

According to the present invention having the above-described configuration, when the tint phase is changed in the negative voltage direction due to thermal runaway of the chroma IC, the tint adjustment voltage applied to the chroma IC by the resistor Rx is positive. The compensation in the positive voltage direction prevents the tint phase from being distorted by the chroma IC.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram illustrating a tint correction circuit of a televideo apparatus according to an exemplary embodiment of the present invention. In FIG. 2, the same reference numerals are given to the same parts as those of FIG.

In FIG. 2, reference numeral 21 denotes an integration circuit for integrating a pulse width modulated signal for tint adjustment output from the microprocessor 7, which is an output terminal of the tint control signal of the microprocessor 7. And a resistor R1 connected in series with (TIN) and a capacitor C1 coupled between the tint control signal output terminal TIN and ground.

The output terminal of the integrating circuit 21 is coupled to the tint adjustment voltage input terminal of the chroma IC 9 through the resistor R3, and the pull-up resistor is connected to the output node of the integrating circuit 21 and the connection node of the resistor R3. Supply voltage is coupled via (R2)

On the other hand, a current path between the resistor R4 and the PNP transistor Q2 is connected in series between the resistor R3 and the connection node of the chroma IC 9 and the ground, and the resistor R4 and the transistor Q2 are connected in series. In parallel with the series connection of the current transistor), the current path of the NPN transistor Q1 and the resistor Rx are connected in series.

In this case, as shown in FIG. 3, the resistance Rx increases as the temperature increases.

The output P of the microprocessor 7 is coupled to the base of the NPN transistor Q1 through the resistance voltage divider R5 and R6 and coupled to the base of the PNP transistor Q2.

On the other hand, the microprocessor 7 outputs a low level control signal P in the normal state, that is, in the TV mode in which the viewer watches a broadcast program through the televideo device, and the viewer controls the remote control device 5. By selecting the video tape playback mode, the control signal P is output at a high level.

Accordingly, in the TV mode, the transistor Q1 is turned off while the transistor Q2 is turned on. In the video mode, the transistor Q2 is turned off while the transistor Q1 is turned on.

That is, in the above configuration, in the TV mode in which the viewer watches a broadcast program, the transistor Q1 is turned off and the transistor Q2 is turned on, so that the tint adjustment signal applied from the microprocessor 7 to the chroma IC 9. The supply line is biased by the resistor R4 having a fixed resistance value.

On the other hand, when the viewer operates the remote controller 5 to select the video playback mode, the transistor Q1 is turned on by the high level control signal P output from the microprocessor 7, and the transistor Q2 is turned on. Will be off.

Therefore, in this case, the tint adjustment signal supply line applied from the microprocessor 7 to the chroma IC 9 is biased by a resistor Rx having a resistance value that varies with temperature. Rx), as described above, the resistance value increases as the temperature rises, and as a result, when the temperature rises, the tint adjustment voltage applied to the chroma IC 9 increases.

Accordingly, in the above embodiment, when the tint phase is changed in the negative voltage direction due to thermal runaway of the chroma IC 9, the tint applied to the chroma IC 9 by the resistor Rx. Since the adjustment voltage is compensated in the positive (+) voltage direction, it is possible to prevent the tint phase from being distorted by the chroma IC 9.

In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the technical gist of the present invention.

As described above, according to the present invention, it is possible to realize the tint correction circuit of the televideo device which can prevent the distortion of the tint phase caused by the temperature rise of the surroundings or the inside of the televideo device during video reproduction.

Claims (1)

First switching means and a transistor connected in series between the tint adjustment signal input terminal of the chroma IC and ground; Second switching means and resistors installed in parallel with the first switching means and the transistor and connected in series between the tint adjustment signal input terminal of the chroma IC and the ground; Selection means for selecting a TV / video mode; And a processor for turning on the second switching means when the TV mode is selected by the selecting means and for turning on the first switching means when the video mode is selected. .