KR100211460B1 - Subsignal white balance correcting apparatus of tv receiver - Google Patents

Abstract

The present invention relates to a sub-signal phantom balance adjustment device of a television receiver which can be preferably applied to a PIP circuit for a YUV format. The apparatus for adjusting the white balance of a sub-screen TV receiver according to the present invention mainly processes a composite video signal for a sub-screen to generate a YUV signal, synthesizes the primary color signal obtained by PIP-processing the YUV signal with a primary color signal for the main screen A sub-screen TV set for generating a screen and a sub-screen, comprising: means for clamping a pedestal section of the U signal and a V signal to a predetermined DC level; and means for arbitrarily increasing or decreasing a DC level of a signal section excluding the clamped pedestal section And a control unit.

Description

Sub-signal white balance adjustment device of TV set

1 is a block diagram showing an apparatus for adjusting a white balance of a negative signal in a conventional sub-

FIG. 2 is a block diagram showing a white balance adjustment apparatus for a sub-signal in the sub-screen television receiver according to the present invention.

FIG. 3 is a waveform diagram for explaining a white balance adjustment operation in the sub-screen television receiver of the present invention; FIG.

DESCRIPTION OF THE REFERENCE NUMERALS

10: Sub-image processing unit 20: PIP processing unit

30: main image processing unit 40: switching unit

50: white balance adjustment unit 60: sub-image processing unit

70: PIP processor 71: clamp circuit

72: clamp pulse generator 80: integration circuit

90: Clamp section 91, 92: Clamp circuit

93: Clamp pulse generator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white balance adjustment device for a negative signal of a television receiver, and more particularly to a white balance adjustment device for a negative signal of a television receiver which can be suitably applied to a recently developed PIP circuit for a YUV format.

A picture in picture (PIP) television receiver (hereinafter referred to as a sub-picture TV receiver) combines video signals from two different signal sources into a main picture area on a single CRT (Cathode Ray Tube) TV receiver that can be simultaneously displayed in the area.

On the other hand, in CRTs, since the luminescent characteristics of the R, G, and B phosphors are not uniform, the raster is colored when the luminance is changed, the color is emitted when the monochrome broadcast is received, There is a problem such that the color changes at the time of the white balance adjustment. In order to solve this problem, all of the TV sets are provided with so-called white balance adjustment means.

FIG. 1 is a block diagram showing an apparatus for adjusting a white balance of a sub-picture in a sub-screen TV receiver employing a conventional RGB format PIP circuit.

Prior to describing the configuration of FIG. 1, the overall video signal processing system of the sub-screen TV receiver will be briefly described as follows. First, a broadcast wave signal of a plurality of channels emitted from the transmitting station to the air is received by an antenna (not shown), and a main tuner (not shown) and a sub tuner (not shown) And the broadcast wave signals of the main channel and the sub channel thus selected are separated into a voice intermediate frequency signal and a video intermediate frequency signal in respective video intermediate frequency amplifiers (not shown). Next, the separated intermediate frequency signals are detected by respective detection circuits (not shown), and become the main composite video signal (CVm) and the sub composite video signal (CVs). The main composite image signal CVm is provided to the main image processing unit 30 as shown in FIG. 1, and is separated into a luminance signal and a color signal. After that, the color signal is demodulated to be a color difference signal. Is mixed with a luminance signal having passed through a predetermined delay time to become the primary color signals (Rm, Gm, Bm).

On the other hand, the sub-composite video signal CVs is provided to the sub-image processing unit 10 to be separated into a luminance signal and a color signal, and then the color signal is demodulated into a color difference signal. And mixed with the luminance signal to obtain a primary color signal. Next, the primary color signal for the sub-picture thus obtained is A / D-converted in the PIP processing section 20 while being compressed at a predetermined ratio by the time division method and then stored in the field memory. Thereafter, do.

The switching unit 40 outputs the primary color signals Rm, Gm and Bm for the main picture and the primary color signals Rs, Gs and Bs for the sub-picture thus obtained to the blanking pulses PBLK provided from the PIP processing unit 20. [ And finally outputs the primary color signals (R, G, B) for driving the CRT.

Reference numeral 50 denotes a white balance adjustment unit for adjusting the white balance of the sub-screen prior to mixing the primary color signals for the sub-screen through the PIP processing unit 20 in the switching unit 40, and the white balance adjustment unit 50 And the gains of the respective primary color signals can be externally adjusted by the variable resistors.

However, in recent years, YUV (Y signal, Y signal, R signal, which is a color difference signal, and V signal, BY signal, which is a color difference signal) A PIP circuit of the YUV format has been developed. In such a PIP circuit for the YUV format, a means for adjusting the white balance of the sub-screen has not been developed. When the PIP circuit is used as it is, the white balance of the sub- There is a problem in that the color of the image is deteriorated.

SUMMARY OF THE INVENTION The present invention has been conceived to solve the above-mentioned problems, and it is an object of the present invention to provide a white balance adjustment method and a white balance adjustment method for a sub-screen TV set, which can be applied to a sub-screen television set using a PIP circuit for YUV format, The purpose of the device is to provide.

According to an aspect of the present invention, there is provided an apparatus for adjusting a white balance of a sub-screen TV receiver, the apparatus comprising: a YUV signal processing unit for processing a composite video signal of a sub- A sub-screen television receiver for generating a main screen and a sub-screen by combining the primary signal and the primary color signal, comprising: means for clamping the pedestal section of the U signal and the V signal to a predetermined DC level; and means for clamping the signal section excluding the clamped pedestal section And means for arbitrarily increasing or decreasing the DC level.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram showing an apparatus for adjusting a white balance of a sub-signal in the sub-screen television receiver according to the present invention. The same reference numerals are assigned to the same components in FIG. 1, and detailed description is omitted.

As shown in FIG. 2, in the present invention, the PIP processing unit 70 is configured for the YUV format. Accordingly, the sub-image processing unit 60 performs Y / C separation on the composite video signal CVs, Color signal, and then demodulates the color signal thus generated to generate a U signal and a V signal which are color difference signals. Further, in the present invention, a clamp circuit 91 for clamping a predetermined section of the U signal to a predetermined bias voltage is provided between the sub-image processing section 60 and the PIP processing section 70, a predetermined section of the V signal is set to a predetermined bar- A clamping circuit 90 for clamping the clamping circuit 91 to the clamping circuit Vc and a clamping pulse generator 93 for specifying the clamping period of the clamping circuits 91 and 92 are added. The output terminals of the clamping circuits 91 and 92 for the U signal and the V signal are connected to the integrating circuit part via respective current limiting resistors. The integrating circuit part receives a pulse width modulation (PWM) signal for control provided from the microprocessor And the integrated DC voltage is superimposed on the output terminals of the clamp circuits 91 and 92.

In the figure, reference numerals C1 to C4 denote coupling capacitors for eliminating unnecessary direct current components included in the processing of the U signal and the V signal, respectively, and Vc denotes a bias voltage (Vc) to the clamp circuits 91 and 92 Vc). ≪ / RTI >

Hereinafter, the operation of the sub-signal white balance adjustment apparatus of the television receiver of the present invention having the above-described configuration will be described in detail.

FIG. 3 is a waveform diagram for explaining a white balance adjustment operation of a sub signal in the sub-screen television receiver of the present invention. First, when the TV receiver operates in the main screen and the sub-screen simultaneous display mode, the sub-image processor 60 separates the composite video signal CVm for the sub-screen into a luminance signal and a color signal, Thereby generating color difference signals, that is, a U signal and a V signal. FIGS. 3 (a) through 3 (c) illustrate the luminance signal Y, the U signal, and the V signal output as described above, respectively. Next, the U signal and the V signal thus outputted are supplied to the respective clamp circuits 91 and 92 with the DC component removed thereafter via the coupling capacitors C1 and C2. The clamp pulse generator 93 outputs a clamp pulse CP as shown in (C), which is made on the basis of the horizontal synchronization signal Hs extracted from the sub composite video signal CVm, to the clamp circuits 91 and 92 The clamp circuits 91 and 92 clamp the pedestal section of the input U signal and the V signal to the bias voltage Vc provided from the DC voltage source.

On the other hand, the integration circuit unit 80 integrates the PWM signals generated by a microprocessor (not shown) based on an external key signal or a detection signal from another circuit to convert the DC voltages Va and Vb obtained by the U- V signal, except for the pedestal section. 3 (e) and 3 (f) show an example of a U 'signal and a V' signal produced through such a process. As can be seen, the U 'signal is a DC level of a section except a pedestal section Is lowered by the voltage level Va. On the other hand, in the V 'signal, the DC level of the section except for the pedestal section becomes higher as a whole by the voltage level Vb.

Next, the U 'signal and the V' signal having undergone such adjustment are provided to the clamp circuit 71 of the PIP processing section 70 with the DC component removed thereafter through the coupling capacitors C3 and C4, 71 clamps the pedestal section of the U 'signal and the V' signal to an arbitrary voltage level. Next, an A / D converter (not shown) adjusts the white balance of the sub signal naturally by performing A / D conversion with the pedestal interval as a reference level. The PIP processing unit 70 also generates a primary color signal based on the color difference signal for which the white balance is adjusted and the primary color signal is synthesized with the primary color signal provided by the main image processing unit 30 by the switching unit 40, .

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

According to the apparatus for adjusting the sub-screen white balance of the television receiver of the present invention as described above, it is possible to quickly and accurately adjust the white balance of the sub signal by applying it to the sub-screen TV set using the PIP circuit for YUV format .

Claims (1)

A sub-screen TV receiver for generating a YUV signal by processing a composite video signal for a sub-picture, and synthesizing a primary color signal obtained by PIP-processing the YUV signal with a primary color signal for a main screen, A means for clamping the pedestal section of the U signal and the V signal to a predetermined DC level, and means for arbitrarily increasing or decreasing the DC level of the signal section excluding the clamped pedestal section. Adjusting device.