KR100211462B1 - The white balance correcting apparatus of tv receiver - Google Patents

Abstract

The present invention relates to a white balance adjustment device for a TV set, which can compensate for a deviation of an automatic adjustment range due to a deviation of a CRT or a related part in a television receiver equipped with an automatic white balance adjustment function, . The present invention relates to a white balance adjustment device for a television receiver, which mainly processes a video signal to generate a color difference signal, and partially feeds back the output of the primary color signal obtained by processing the generated color difference signal, Means for arbitrarily changing a direct current level of a color difference signal obtained in the video signal processing step and means for adjusting the white balance of the pedestal section of the color difference signal having the changed direct current level, To a predetermined direct current level and providing the signal to the reproduction process of the primary color signal.

Description

White balance adjustment device of TV receiver

FIG. 1 is a block diagram showing a white balance adjustment device in a conventional television receiver; FIG.

FIG. 2 is a block diagram showing a white balance adjustment device of a television receiver according to the present invention; FIG.

FIG. 3 is a waveform diagram for explaining a white balance adjustment operation in the television receiver according to the present invention; FIG.

DESCRIPTION OF THE REFERENCE NUMERALS

10: Image processor 1: Clamp pulse generator

12: clamp circuit 20: white balance adjustment section

21, 22, 23: bias circuit 24: brightness control circuit

25, 26, 27: Amplification circuit 30:

40: white balance adjustment unit 41: comparator

42, 43:

The present invention relates to a white balance adjustment device for a television receiver, and more particularly, to a white balance adjustment device for a television receiver equipped with an automatic white balance adjustment function, And an adjustment device.

CRTs mainly used as a display device in a television receiver (hereinafter referred to as a TV receiver) are not uniform in light emission characteristics of the R, G, and B phosphors, so that when the luminance is changed, the rasters are colored, There arises a problem that the color changes when receiving a color broadcast. In order to solve this problem, all of the TV receivers are provided with a so-called white balance adjustment means.

FIG. 1 is a block diagram showing a white balance adjustment device in a conventional television receiver. Before describing the white balance adjustment device, a video processing system of a TV receiver will be briefly described. The TV receiver receives broadcast waves radiated to the air from the transmitting station through an antenna and passes only broadcast waves of a desired channel among the broadcast waves of the plurality of channels received by the tuner. The intermediate frequency amplifying unit mixes the selected broadcast wave with an oscillation signal generated by the TV itself to obtain a predetermined intermediate frequency (IF) signal and then amplifies it. The P / S separating unit amplifies the audio intermediate frequency signal SIF ) And the image intermediate frequency signal (PIF). The image detecting unit detects the obtained intermediate frequency signal PIF to generate a composite image signal CV and the image processing unit 10 appropriately processes the composite image signal CV to generate the primary color signals R, B). The primary color symbols (R, G, B) thus produced are provided to the CRT driving unit after adjustment of the white balance, and the CRT driving unit generates the image by driving the CRT based on the primary color signals. In the conventional television receiver having the above-described image processing system, the white balance adjustment unit 20 includes bias circuits 21 to 23 for each primary color signal, a brightness control circuit 24, amplifier circuits 25 to 27, And resistors R1 to R6. In the above configuration, each of the bias circuits 21 to 23 feeds back some of the currents classified by the voltage division resistors R1 to R6 at the output terminals of the amplifier circuits 25 to 27, G, and B), the white balance is automatically adjusted. The brightness control circuit is a circuit for adjusting the brightness of the screen. The white balance automatic adjustment unit 20 may be provided inside the image processing unit 10, i.e., a single chroma IC. The U terminal and the V terminal shown in the image processing unit 10 are respectively connected to a color difference signal (U signal represents RY signal and V signal represents a color difference signal) for PAL (Phase Alteration by Line) BY signal).

According to the conventional television receiver as described above, the white balance is automatically adjusted by adjusting the respective bias by the R, G, and B feedback currents. However, the white balance is automatically adjusted by the deviation of the CRT or other related parts, There is a problem in that it can not compensate at all.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a television receiver equipped with an automatic white balance adjustment function that compensates for a deviation from an automatic adjustment function due to a deviation of a CRT or a related part, So as to more faithfully reproduce the white balance of the TV set.

According to an aspect of the present invention, there is provided an apparatus for adjusting a white balance of a TV receiver, the apparatus comprising: a color difference signal processing unit for processing a video signal to process a color difference signal; And adjusting a bias state of the primary color signal of the color difference signal to thereby automatically adjust the white balance, the television receiver comprising: means for arbitrarily changing the DC level of the color difference signal obtained in the video signal processing step; And a means for clamping a pedestal section of the color difference signal having a predetermined direct current level and providing the clamped signal to the reproduction process of the primary color signal.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments of a white balance adjustment apparatus for a television receiver according to 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 white balance of a television receiver according to the present invention. The same reference numerals are assigned to the same components as those in FIG. 1, and a detailed description thereof will be omitted.

2, the present invention additionally includes a white balance adjustment unit 40 and an integration circuit unit 30 that are tightly coupled to the image processing unit 10. Before the description thereof, the image processing unit 10 ) Will be described in detail. The image processing unit 10 illustrated in this embodiment is a so-called YUV format image processing unit. The image processing unit 10 demodulates the color signals obtained by processing the composite video signal CV to generate color difference signals U ₀ and V ₀ ), And outputs the color difference signals U ₀ and V ₀ thus obtained to the outside for conversion and PIP processing to the PAL system. Next, the DC components included in the color difference signals U ₀ and V ₀ are removed by the coupling capacitors C 1 and C 2, and then input again to generate the primary color signals R, G, and B. The image processing unit 10 is further provided with a clamp circuit 12 and a clamp pulse generating circuit 11. The clamp circuit 12 compares the color difference signals U ₀ and V ₀ ), for example, a pedestal section is clamped at a predetermined DC level to regenerate a DC component. The clamp pulse generating circuit 11 provides a pulse for instructing the pedestal section to the clamp circuit 12 .

Next, the white balance adjustment unit 40 is connected to the color difference signal output terminals U ₀ and V ₀ of the image processing unit 10. The white balance adjustment unit 40 generates a predetermined clamp interval, for example, a pulse indicating a pedestal interval Two switching circuits 42 and 43 switched in synchronism with the clamp pulse CP outputted from the comparator 41 and a switching circuit 42 and 43 connected to the respective one input terminals of the switching circuits 42 and 43, And voltage dividing resistors R11 and R12 for applying a predetermined reference voltage Vref to the resistor R11. Reference numerals C3 and C4 denote coupling capacitors for eliminating the DC component contained in the white balance adjustment process.

Next, the integration circuit section 30 generates an arbitrary DC voltage Va or Vb obtained by integrating the PWM signal provided by, for example, a microprocessor (not shown) and outputs the DC voltage Va or Vb of the color difference signals U ₀ and V ₀ And performs a function of changing the DC level. In the drawings, reference numerals C5, C6 and R8, R9 denote resistors and capacitors for surge absorption, respectively, and reference numerals R9, R10 denote current limiting resistors.

Hereinafter, the operation of the white balance adjustment device of the TV receiver of the present invention will be described.

FIG. 3 is a waveform diagram for explaining a picture balance adjustment operation in the television receiver according to the present invention; FIG. First, when a TV receiver is turned on and a broadcast is caught, the image processing unit 10 processes the composite video signal CV to generate a luminance signal (third (a) and color difference signals U ₀ and V ₀ ). The generated color difference signals U ₀ and V ₀ are applied to one input terminal (L terminal) of each of the switching circuits 42 and 43 while their DC components are removed by the coupling capacitors C1 and C2. , The comparator 41 outputs a sand cast pulse (SCP) formed by horizontal and vertical sync pulses and a color burst pulse to a predetermined direct current voltage Vx (the direct current voltage is determined based on the voltage level of the sand cast pulse (Hereinafter, referred to as a clamp pulse) for controlling the switching operation of the switching circuits 42 and 43, as compared with a case where the DC voltage level exceeds the DC voltage level. Figure 3 (d) shows the resulting clamp signal. , Each of the switching circuits 42 and 43 is there is to be switched into the L state while not the clamp signal (CP) occurs, outputs a color difference signal (U ₀ and V _0), thus outputting the color difference signals (U ₀ And V ₀ are superimposed on an arbitrary direct current level Va or Vb output from the integrating circuit portion 30 to change the levels as shown in Figures 3 (c) and 3 (d). The respective switching circuits 42 and 43 are switched to the H state during the generation of the clamp signal CP so that a predetermined period of the color difference signals U ₀ and V ₀ , The DC level Va or Vb of the color difference signals U ₀ and V ₀ outputted through the white balance adjustment section 40 is clamped to the reference voltage Vref. as shown in Fig. 5 (f), the pedestal level Vref is lowered or raised as a whole. Next, The level-adjusted color difference signals U ' ₀ and V' ₀ are supplied to the image processing unit 10 with the DC component removed by the coupling capacitors C3 and C4. The image processing unit 10 reproduces the DC component of the color difference signal by the clamp circuit 12 and generates the primary color signal based on the reproduced color difference signal and provides it to the conventional white balance automatic adjustment unit 20 . Therefore, the problem of white balance can be completely solved by providing the white balance unbalance caused by the deviation of the CRT or other related parts within a range that can be processed by the conventional automatic adjustment unit.

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.

As described above, according to the white balance adjustment device of the television receiver of the present invention as described above, it is possible to compensate for the case where the automatic adjustment range is deviated by the deviation of the CRT or the related part in the television receiver provided with the white balance automatic adjustment function, The image can be reproduced more faithfully.

Claims (1)

The bias state for each primary color signal is adjusted by partially feeding back the output of the primary color signal obtained by processing the generated color difference signal by processing the video signal to thereby automatically adjust the white balance Wherein the means for arbitrarily changing the direct current level of the color difference signal obtained in the video signal processing step and the pedestal section of the color difference signal having the changed direct current level are clamped to a predetermined direct current level, And adjusting the white balance of the TV set to a predetermined value.