KR100228215B1 - Circuit for adjusting sub-picture bright of television receiver - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a sub-screen brightness control circuit of a television receiver capable of arbitrarily adjusting brightness of a sub-screen from a sub-screen television receiver.

The present invention is a sub-screen television receiver for adjusting a brightness of a sub-screen by setting a level obtained by processing a composite video signal for a sub-channel in the sub-image processing unit 140 and clamping the generated luminance signal to a black reference level, The luminance signal from the sub-picture processing unit is supplied to the sub-picture processing unit during a period in which switching is controlled by the clamp pulse from the clamp pulse generating circuit and no clamp pulse is generated, A control means for clamping the brightness signal to a predetermined DC level while the clamp pulse is generated, a control means for outputting a digital control signal for controlling the brightness according to an arbitrary brightness amount set by the key setting means, And a digital control signal output from the control means is converted into a corresponding DC voltage Characterized in that configured by including the D / A conversion means for supplying to an output terminal of the switching means such that the black level subtraction based on the DC level of the predetermined voltage by the DC.

Description

The sub-picture brightness control circuit of the television receiver

FIG. 1 is a block diagram showing a video processing system of a general sub-screen television receiver.

FIG. 2 is a block diagram showing a sub-screen brightness processing system of a conventional sub-screen television receiver.

FIG. 3 is a waveform diagram for explaining the configuration shown in FIG. 2; FIG.

FIG. 4 is a block diagram showing a sub-screen brightness control circuit of a television receiver according to a preferred embodiment of the present invention; FIG.

FIG. 5 is a waveform diagram for explaining the configuration shown in FIG. 4; FIG.

DESCRIPTION OF THE REFERENCE NUMERALS

10: antenna 20: distributor

30: main tuner 40: main PIF section

50: main switching unit 60: Y / C separation unit

70: main image processing unit 80: deflection / high voltage circuit unit

100: Sub tuner 110: Sub PIF section

120: secondary switching unit 130: primary / secondary switching switch

140: Sub-image processing unit 150: PIP processing unit

151: Clamp circuit 152: Clamp voltage generating circuit

160: switching unit 170: CRT driver

180: CRT 200: system controller

210: last memory 220: key input unit

230: Receiving unit 240:

250: D / A conversion section

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sub-screen brightness control circuit for a television receiver, and more particularly, to a sub-screen brightness control circuit of a television receiver capable of arbitrarily adjusting the brightness of a sub- .

As is well known, a sub-screen television receiver is a television receiver that divides a part of a main screen, which is reproduced through a full screen area of a CRT (Cathode Ray Tube), into one or more, A television receiver capable of simultaneously viewing two or more channels of broadcasting by allowing the screen of the channel to be reproduced as a small screen.

FIG. 1 is a block diagram showing a video processing system of a general sub-screen television receiver, FIG. 2 is a block diagram showing a sub-screen brightness processing system of a conventional sub-screen television receiver, 1 is a waveform diagram for explaining a configuration.

As shown in FIG. 1, in a general sub-screen television receiver, after receiving a broadcast wave signal of a plurality of channels emitted from the transmitting station to the air by the antenna 10, a broadcast wave of a main channel and a sub- Only the signal is selected by the main tuner 30 and the sub tuner 100 via the distributor 20. [ The broadcast wave signal of the main channel thus selected is separated into the audio intermediate frequency signal SIF and the video intermediate frequency signal PIF in the main video intermediate frequency amplifying unit 40 PIF are detected and converted into a composite video signal CV and then input to the main switching unit 50.

The composite video signal CV is separated into a luminance signal Y and a color signal C by the Y / C separation unit 60 and is provided to the main image processing unit 70. In the main image processing unit 70, The luminance signal Y and the color signal C thus provided are processed to output the negative luminance signal -Y and the color difference signals RY, GY, BY. The deflection and high voltage circuit unit 80 generates a deflection signal and a high voltage DC voltage based on the horizontal synchronization signal H _M and the vertical synchronization signal V _M provided from the main image processing unit 70 and supplies the deflection signal and the high voltage DC voltage to the CRT 180 .

The broadcast wave signal of the subchannel selected by the sub tuner 100 is converted into a composite video signal CV via the sub PIF unit 110 and then transmitted to the sub image processor 140 via the sub switch 120. [ . A plurality of external image input terminals V1 to V3 are commonly connected to the main switching unit 50 and the secondary switching unit 120. The main switching unit 50 and the secondary switching unit 120 are connected to a system The main image processing unit 70 or the sub-image processing unit 140, respectively, according to the control of the control unit 200, only the signal selected from the composite video signal of the main channel or the sub-channel or the external video signal. The main / secondary changeover switch 130 is provided for switching the main channel to the sub-image processing unit 140 and the sub-channel to the main image processing unit 70 under the control of the system control unit 200. [

The sub image processor 140 separates the composite video signal CV of the subchannel into the luminance signal Y and the color signal C and then outputs the luminance signal Y and the color difference signals RY and BY . The PIP processor 150 includes functional blocks such as an A / D converter, a plurality of field memories, a D / A converter, and a matrix circuit. In the A / D converter, Y) and the color difference signals RY and BY into a predetermined bit, for example, a 6-bit digital signal by a time division scheme, and the field memory stores the converted digital signal and outputs it to a D / A converter .

At this time, the D / A converter converts the digital signal thus converted into an analog signal again, and the matrix circuit performs matrix processing on the converted luminance signal and color difference signal to output them as primary color signals (R, G, B). The luminance signal -Y and color difference signals RY, GY and BY provided by the main image processing unit 70 and the primary color signals R, G and B provided by the PIP processing unit 150 are supplied to the PIP processing unit 150, The switching unit 160 is switched by the blanking signal PBLK output from the CRT driving unit 170 and supplied to the CRT driving unit 170. [ The CRT driver 170 converts the provided luminance signal -Y and the color difference signals RY, GY and BY into a primary color signal R, G and B, and then drives the CRT 180, The sub screen is reproduced at the same time as the main screen.

The system controller 200 receives various key signals through the key input unit 220 provided in the main body of the television receiver or receives the remote key signals transmitted from the remote controller 225 through the receiver 230, And then controls each part of the receiver.

That is, the channel tuning operation by the main tuner 30 and the sub tuner 100 and the switching operation of the various switching units 50, 120, 130, and 160 are controlled, and the main image processing unit 70 and the sub- (H _M , H _S ) and vertical synchronization signals (V _M , V _S ) from the video signal processor 140 to precisely synchronize the main screen and the sub screen and control the size and the dispatch position of the sub screen . The system control unit 200 controls the main image processing unit 70 to adjust the screen state such as image quality, color, color density, brightness, and the like, outputs a control signal related to the OSD, Is displayed.

In the figure, reference numeral 210 denotes a last memory. The number of main channels and subchannels, the switching states of the various switching units 50, 120, 130, and 160, Is stored under the control of the controller (200), and is reproduced in a state before the power is turned off at the time of turning on the power.

2, the composite video signal CV is output from the sub-picture processor 140 to the luminance signal Y and the chrominance signal Y. In the sub-picture processor of the conventional sub-screen television receiver, Are separated into signals RY and BY, and then supplied to the PIP processor 150 to be subjected to A / D conversion. However, in the case of the luminance signal Y, the DC component is removed by the cuffing capacitor C1 before the A / D conversion, and then the clamp pulse generation circuit 152, as shown in FIG. 3 (b) The clamp circuit 151 clamps the portion indicated by the bold line in FIG. 3 (a) to a predetermined level in synchronization with the clamp pulse generated in the clamping circuit 151 (normally coinciding with the color burst signal period). The clamped level is regarded as the black reference level at the subsequent A / D conversion.

However, in the conventional sub-screen television receiver configured as described above, the brightness of the sub-screen can be clamped to a preset value by the clamp circuit 151, unlike the case where the brightness of the main screen can be arbitrarily adjusted from outside There is a problem in that it can not be arbitrarily adjusted according to the taste of the user.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a television receiver capable of arbitrarily adjusting the brightness of a sub-screen independently from an adjustment state of brightness of a main screen, And a sub-screen brightness control circuit for controlling the brightness of the sub-screen.

According to an aspect of the present invention, there is provided a sub-screen brightness control circuit for a television receiver, the sub-screen brightness control circuit including a sub- And adjusting the brightness of the sub-picture by setting the clamped level to a black reference level, the sub-screen television receiver comprising key setting means for performing a key operation for arbitrarily setting the brightness of the sub-picture, The luminance signal from the sub-image processing unit is bypassed during a period in which the clamp pulse is not generated for the luminance signal of the sub-screen and the switching signal is controlled by the clamp pulse from the pulse generating circuit. While the clamp pulse is generated, Switching means for clamping the electric power to a predetermined direct current level, Control means for outputting a digital control signal for controlling the brightness in accordance with a set arbitrary brightness amount; and control means for converting the digital control signal output from the control means into a corresponding DC voltage, And D / A converting means for supplying the output of the switching means so that the black level for the luminance signal of the sub-picture is added or subtracted on the basis of the level of the luminance signal of the sub-screen.

Hereinafter, preferred embodiments of the present invention will be described in detail.

FIG. 4 is a block diagram showing a sub-screen brightness control circuit of a television receiver according to a preferred embodiment of the present invention, and a portion not directly related to the present invention is omitted.

4, in the sub-screen brightness control circuit of the television receiver according to the preferred embodiment of the present invention, the luminance signal output terminal Yout of the sub-image processing unit 140 and the luminance signal input terminal of the PIP processing unit 150 A switching unit 240 is provided between the terminals for switching the input by a clamp pulse. A luminance signal Y having a DC component removed by a coupling capacitor C2 is connected to one input terminal of the switching unit 240 And a predetermined DC voltage Va obtained by properly dividing the power supply voltage Vcc by a variable resistor is connected to the other input terminal. The output terminal of the switching unit 240 is connected to the clamp circuit 151 of the PIP processing unit 150 via a coupling capacitor C1 as in the conventional case. The switching unit 240 is connected to the PIP processing unit 150 And is controlled by the clamp pulse generated from the clamp pulse generating circuit 152.

If the switching unit 240 is at the "L" level at which the clamp pulse is not supplied in FIG. 5 (d), its switching state is switched to the "L" state, When the clamp pulse is supplied, the switching state is switched to the " H " state, and the DC voltage Va (Va ) Is outputted to clamp the luminance signal.

The D / A converter 250 is connected between the output terminal of the switching unit 240 and the coupling capacitor C1. The D / A converter 250 is connected to the key input unit 220, The digital control signal from the system control unit 200, which is controlled according to the key operation of the function key for adjusting the brightness of the sub-screen disposed in the sub-screen 225, converts the digital control signal into the corresponding DC voltage V _DA , (See Figs. 5 (b) and 5 (c)).

Hereinafter, the operation of the sub-screen brightness control circuit according to the present invention will be described in detail.

FIG. 5 is a waveform diagram for explaining the configuration shown in FIG.

First, in the television receiver according to the present invention, a key for adjusting the brightness of a sub-screen is additionally provided to the key input unit 220 or the remote controller 225 so that the brightness of the sub-screen can be input from the outside. The sub-tuner 100, the sub-PIF unit 110, the sub-switching unit 120, the sub-tuner 100, and the sub-tuner 100 according to the control of the system controller 200. [ Is processed through the sub-image processing unit 140, the PIP processing unit 150 and the switching unit 160 (see FIG. 1), and is displayed as a sub-screen image on a designated screen portion of the screen of the CRT 180.

During the period in which the clamp pulse is not applied as shown in FIG. 5 (d), the switching unit 240 is switched to the "L" state and, as shown in FIG. 5 The luminance signal Y from which the DC level has been removed by the capacitor C2 is bypassed as it is.

Next, in the fifth step (d), while the clamp pulse is applied, the switching unit 240 is switched to the "H" state to clamp the corresponding luminance signal period to the predetermined DC level Va. The digital control signal output from the system controller 200 corresponding to the amount of brightness input from the outside is input to the bypassed luminance signal Y via a DC voltage V _DA obtained by conversion in the D / As shown in FIGS. 5 (b) and 5 (c), the DC level Va is added or subtracted from the reference level.

As a result, when the DC component of the added and subtracted luminance signal is removed by the coupling capacitor C2 and then applied to the clamp circuit 151 provided in the conventional PIP processor 150, the average of the luminance signals The level is changed, and when it is processed and reproduced on the screen, a sub-picture having the changed brightness is obtained.

The present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the technical gist of the present invention.

According to the sub-screen brightness control circuit of the television receiver of the present invention as described above, the brightness of the sub-screen can be arbitrarily changed from the outside, thereby satisfying various needs of the user.

Claims (1)

The luminance signal generated by processing the composite video signal for the sub-channel in the sub-image processing unit is clamped in the pulse interval of the clamp pulse generated from the clamp pulse generation circuit, and the clamped level is set as the black reference level, And a control unit for performing a key operation for performing a key operation for arbitrarily setting the brightness of the sub-screen, wherein the brightness of the sub-screen is controlled by the clamp pulse from the clamp pulse generation circuit, Switching means for bypassing the luminance signal from the sub-image processing unit during a period in which the clamp pulse is not generated and clamping the luminance signal to a predetermined DC level during the generation of the clamp pulse; Outputs a digital control signal to control brightness according to the amount of brightness And a switching circuit for switching the digital control signal outputted from the control means to the corresponding DC voltage so that the black level for the luminance signal of the sub- And a D / A conversion means for supplying the D / A conversion means to an output terminal of the sub-screen brightness adjusting circuit.