JPH05183845A - Television receiver - Google Patents

Abstract

PURPOSE:To obtain the best level without being affected by a beam current suppressing circuit by controlling the gain by a dedicated gain controlling means corresponding to the contrast level of a video signal when on-screen characters of channel information, audio information, etc., are displayed on the TV receiver. CONSTITUTION:A contrast control signal generating circuit 2 outputs a control signal corresponding to contrast data supplied by user operation and a contrast control circuit 3 controls the contrast and inputs the video signal to a composing circuit 5. Further, a beam current suppressing circuit 6 detects a beam current with a current flowing to a flyback transformer so as to suppress the flow of an excessive current to a cathode-ray tube, and turns ON a diode 6b when the detected current is excessive to decrease the bias of the contrast control signal, thereby suppressing the beam current. The contrast control signal generated by the circuit 2 is converted by a newly provided gain control circuit 4 to the best controllable level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver having a function of displaying on-screen characters such as channel information and audio information on a display such as a cathode ray tube.

[0002]

2. Description of the Related Art A conventional television receiver of this type will be described below with reference to FIG.

Input to a video signal input terminal 1 of a contrast control circuit 3 for controlling the contrast of the video signal by a contrast control signal generated by a contrast control signal generating circuit 2 in accordance with contrast control data given by a user's operation. The end is connected to the output terminal of the contrast control circuit 3, and the video signal contrast-controlled by the contrast control circuit 3 and the gain adjusting circuit 4 are connected.
The video signal input end of the synthesizing circuit 5 for synthesizing the gain-adjusted on-screen signal is connected, and the output end of the synthesizing circuit 5 is connected to the input end of a CRT (CRT) drive circuit (not shown). It will be done.

The input terminal 6 of the contrast control data is connected to the input terminal 6 of the contrast control data, and the input terminal of the contrast control signal generation circuit 2 for generating the contrast control signal according to the contrast control data is connected to the input terminal of the contrast signal generation circuit 2. , A flyback transformer (hereinafter referred to as F, B, T) for connecting the contrast control signal input terminal of the control control circuit 3 and for suppressing an excessive beam current from flowing in a cathode ray tube (not shown) depending on the image content. ..
A diode 6 for detecting and suppressing the beam current of the cathode ray tube (not shown) by a current flowing through the diode 6 (not shown).
The input terminal of a beam current suppression circuit (hereinafter, referred to as A, B, L circuit) 6 composed of a, a resistor 6b, etc. is connected, and the contrast control signal generated by the contrast control signal generation circuit 2 is adjusted in gain. An input terminal of a level shift circuit 7 for converting to an optimal controllable level of the circuit 4 for output is connected, and an output terminal of the level shift circuit 7 is connected to a control signal input terminal of the gain adjusting circuit 4. It is a thing.

At the output end of the on-screen character generator 8 for generating on-screen characters such as channel information and voice information and outputting an on-screen signal, the on-screen character output from the on-screen character generator 8 is generated. The on-screen signal input terminal of the gain adjusting circuit 4 for adjusting the gain of the signal by the contrast control signal whose level is converted by the level shift circuit 7 is connected, and the output terminal of the gain adjusting circuit 4 is turned on of the synthesizing circuit 5. The screen signal input terminal is connected.

The operation of the television receiver configured as described above will be described below.

A contrast control signal generation circuit 2 generates a contrast control signal in accordance with contrast control data given by a user's operation, and the contrast control signal is input from a video signal input terminal 1 to the contrast control circuit 3 by the contrast control signal. The contrast of the video signal is controlled, and the video signal subjected to the contrast control is synthesized.
It is what you enter into.

In order to prevent an excessive beam current from flowing through a cathode ray tube (not shown) depending on the image content, F,
The beam currents of the cathode ray tube (not shown) are detected by the A, B, L circuits 6 by the currents flowing in B, T (not shown), and when the beam current is excessive, the diode 6a conducts and the contrast increases. The bias of the control signal is reduced to suppress the beam current, and the level shift circuit 7 converts the contrast control signal generated by the contrast control signal generation circuit 2 into a level that can be optimally controlled by the gain adjustment circuit 4 and outputs the level. It will be done.

The on-screen character generator 8 generates on-screen characters such as channel information and voice information to output an on-screen signal, and the gain adjusting circuit 4 converts the level by the bell shift circuit 7. The gain of the above-mentioned on-screen signal is adjusted by the contrast control signal, and the contrast-controlled video signal and the gain-adjusted on-screen signal are synthesized by the synthesizing circuit 5, and a CRT (CRT) drive circuit (not shown) is synthesized. Then, the combined video signal and on-screen signal are amplified and received by a cathode ray tube (not shown).

[0010]

However, in the above-mentioned conventional television receiver, the A, B and L circuits are configured so that the beam current of the cathode ray tube does not become excessive when the image content is entirely bright. Diode will conduct and the bias of the contrast control signal will decrease,
The gain of the on-screen signal is also reduced, and there is a problem that the level of the on-screen signal is reduced and the distinguishability of the on-screen display is reduced even though the image content is bright. When the gain adjustment circuit fixes the on-screen signal level at a high level with a fixed bias in order to obtain distinction when bright, when the user lowers the contrast of the video signal according to their preference, the on-screen signal level is high. Therefore, there is a problem that the on-screen display is very annoying.

[0011]

A television receiver according to the present invention comprises a gain adjustment control means for exclusively controlling the gain adjustment of an on-screen signal according to the contrast level of a video signal. ..

[0012]

In the television receiver according to the present invention, the gain adjustment control means can control the gain adjustment of the on-screen signal according to the contrast level of the video signal without being affected by the A, B and L circuits. Because you can
The level of the on-screen signal can be controlled to the optimum level.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the television receiver of the present invention will be described below with reference to FIG. 1. The same parts as those of the conventional example will be described using the same reference numerals.

Input to a video signal input terminal 1 of a contrast control circuit 3 for controlling the contrast of the video signal by a contrast control signal generated by a contrast control signal generating circuit 2 according to a contrast control data given by a user's operation. The end is connected to the output terminal of the contrast control circuit 3, and the video signal contrast-controlled by the contrast control circuit 3 and the gain adjusting circuit 4 are connected.
The video signal input end of the synthesizing circuit 5 for synthesizing the gain-adjusted on-screen signal is connected, and the output end of the synthesizing circuit 5 is connected to the input end of a CRT (CRT) drive circuit (not shown). It will be done.

The input terminal 6 of the contrast control data is connected to the input terminal 6 of the contrast control data, and the input terminal of the contrast control signal generating circuit 2 for generating the contrast control signal according to the contrast control data is connected to the output terminal of the contrast signal generating circuit 2. , The contrast control signal input terminal of the contrast control circuit 3 is connected, and the currents flowing through F, B, T (not shown) are suppressed in order to prevent an excessive beam current from flowing through a cathode ray tube (not shown) depending on the image content. A, B, L composed of a diode 6a, a resistor 6b, etc. for detecting and suppressing the beam current of the cathode ray tube (not shown) by
A gain adjustment control signal generation circuit 9 which is a gain adjustment means for connecting an input terminal of the circuit 6 and further for generating a gain adjustment control signal of an on-screen signal to the contrast control data input terminal 6 according to the contrast control data. Connected to the output terminal of the gain adjustment control signal generation circuit 9 and the control signal input terminal of the gain adjustment circuit 4 for adjusting the gain of the on-screen signal by the gain adjustment control signal. Is.

Further, the gain of the on-screen signal is adjusted at the output end of the on-screen character generator 8 for generating an on-screen character such as channel information and audio information and outputting the on-screen signal. The on-screen signal input terminal of the gain adjustment circuit 4 which is adjusted by the gain adjustment control signal generated at 9 is connected, and the on-screen signal input terminal of the synthesis circuit 5 is connected to the output terminal of the gain adjustment circuit 4. It is a thing.

The operation of the television receiver configured as described above will be described below.

A contrast control signal generating circuit 2 generates a contrast control signal according to the contrast control data given by a user's operation, and the contrast control signal is inputted from the video signal input terminal 1 to the contrast control circuit 3 by the contrast control signal. The contrast of the video signal is controlled, and the video signal subjected to the contrast control is synthesized.
It is what you enter into.

Further, in order to prevent an excessive beam current from flowing through a cathode ray tube (not shown) depending on the image content, F,
The beam currents of the cathode ray tube (not shown) are detected by the A, B, L circuits 6 by the currents flowing in B, T (not shown), and when the beam current is excessive, the diode 6a conducts and the contrast increases. The bias of the control signal is lowered to suppress the beam current, and the gain adjustment control signal generation circuit 9 generates the gain adjustment control signal of the on-screen signal according to the contrast control data.

Further, the on-screen character generator 8 generates on-screen characters such as channel information and voice information to output an on-screen signal, and the gain adjusting circuit 4 generates the gain adjusting control signal generating circuit 9. The gain of the on-screen signal is adjusted by the gain adjustment control signal, and the contrast-controlled video signal and the gain-adjusted on-screen signal are synthesized by the synthesis circuit 5, and a CRT (CRT) drive circuit (not shown) is synthesized. ), The combined video signal and on-screen signal are amplified and received by a cathode ray tube (not shown).

In the above case, the output terminal of the gain adjustment control signal generation circuit 9 is connected only to the input terminal of the gain adjustment circuit 4, and the gain adjustment control for exclusively performing the gain adjustment control of the on-screen signal is performed. To generate a signal, A,
Even if the video contents are bright and the A, B, L circuits 6 act without being affected by the B and L circuits 6, the gain of the on-screen signal does not decrease and increases according to the contrast level of the video signal. Is adjusted so that the distinctiveness of the on-screen display can be maintained,
Further, even when the user operates the contrast control data according to his / her preference to lower the contrast of the video signal, the gain of the on-screen signal is also reduced according to the contrast level of the video signal, which makes the on-screen display obtrusive. There is no such thing.

[0022]

Since the television receiver of the present invention has the above-mentioned configuration, the gain adjustment control means A,
Since the gain adjustment of the on-screen signal can be controlled according to the contrast level of the video signal without being affected by the B and L circuits, it is possible to control the level of the on-screen signal to the optimum level. ..

[Brief description of drawings]

FIG. 1 is a principal block diagram showing an embodiment of a television receiver of the present invention.

FIG. 2 is a block diagram of essential parts showing a conventional television receiver.

[Explanation of symbols]

 9 Gain adjustment control signal generation circuit

Claims (1)

[Claims] 1. In a television receiver having a function of displaying on-screen characters such as channel information and audio information on a display such as a cathode ray tube, control of gain adjustment of on-screen signals according to the contrast level of video signals. A television receiver comprising a gain adjustment control means for exclusively performing the above.