JPH07226952A - White balance adjustment circuit - Google Patents

Abstract

PURPOSE:To simplify the white balance adjustment by generating a primary color signal from a white video signal, comparing one of primary color signals as a reference with other primary color signals and displaying the result of coincidence. CONSTITUTION:This adjustment circuit is constituted of amplifiers 1, 11, 21 amplifying R, G, B primary color signals with variable gains for each signal, adjustment operation sections 2, 12, 22 for the amplifiers, a picture tube 3 displaying a picture, a 1st A/D converter section 4, a 2nd A/D converter section 14 and a 3rd A/D converter section 24 converting an output signal of the amplifiers into a digital signal, a 1st adjustment section 5 and a 2nd adjustment section 25 adjusting a level of a digital signal for comparison reference, a 1st comparator section 7 comparing an output of the 1st A/D converter section 4 with an output of the 1st adjustment section 5, a 2nd comparator section 17 comparing an output of the 3rd A/D converter section 4 with an output of the 2nd adjustment section 25, a 1st display section 8 displaying the result of comparison of the 1st comparator section 7 and a 2nd display section 18 displaying the result of comparison of the 2nd comparator section 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white balance adjusting circuit used for adjusting the white balance of a television or the like before shipment at a factory.

[0002]

2. Description of the Related Art When a black-and-white image is reproduced on a display monitor or the like, it must be achromatic at various brightnesses of the screen. Call it adjustment.
Conventionally, the white balance is adjusted at the time of factory shipment.
The method as shown in FIG. 3 is performed. According to this method, a white video signal is supplied as a reference signal for adjustment, and the R, G, B primary color signal waveforms obtained at that time are observed by the adjuster 41 with the oscilloscope 40, and are determined in advance. This is a method of adjusting the gain of the amplifier 1 by operating the volume 2 so that a standard waveform for each primary color can be obtained. Therefore, it takes adjustment time and requires specialized adjustment technology such as observing the waveform. Therefore, there is a problem that it is difficult to simplify the adjustment.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a white balance adjusting circuit which can be easily adjusted without using a measuring instrument such as an oscilloscope. And

[0004]

In order to achieve the above object, an amplifier for changing and amplifying each R, G, B primary color signal and an adjusting operation section for adjusting the gain for each amplifier are provided. In the white balance adjusting circuit, the first A / D conversion unit, which is provided for each output of the amplifier, converts each output signal into a digital signal at a required sample time and quantization level, and a second A / D conversion unit. And a third A / D converter, and the above 3
A first comparing section that receives any one of the A / D converting sections as a reference signal input and two other digital signals as a comparison signal input; a second comparing section; The first display unit that displays the comparison result of the comparison unit and the second display unit that displays the comparison result of the second comparison unit.

[0005]

With the above configuration, for example, for white balance adjustment, the video signal input of the reference white signal is supplied to the television, and the first comparing section and the second comparing section are provided with, for example, , G is set to an adjustment state in which the primary color signal is applied as a reference signal input. First, the gain of the amplifier that amplifies the R primary color signal is changed, and adjustment is made so that, for example, the lamp of the first display unit is turned on. Next, the gain of the amplifier that amplifies the B primary color signal is changed, and adjustment is made so that, for example, the lamp of the second display unit is turned on.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A white balance adjusting circuit according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of a white balance adjusting circuit according to the present invention. 1 is
An amplifier for changing the gain of an input signal and amplifying it, for example, is an R signal, and the amplifier 1 includes an adjusting operation unit 2 for adjusting the gain, for example, a variable volume. 3 is R,
It is a picture tube that is driven by G and B primary color signals and displays an image. Reference numeral 4 is a first A / D conversion unit for converting the R output signal of the amplifier 1 into a digital signal at a required sample time and quantization level. Reference numeral 5 is a first adjusting unit for adjusting the magnitude of the digital signal for the comparison reference. 7
Is a first comparison unit that compares the output of the first A / D conversion unit 4 and the output of the first adjustment unit 5. Reference numeral 8 is a first display unit which displays the comparison result of the first comparison unit and which is, for example, an LED. Reference numeral 11 denotes, for example, an amplifier for G signals, and the amplifier 11 includes an adjustment operation unit 12 for adjusting the gain, for example, a variable volume. 14
Is a second A / D converter that converts the G output signal of the amplifier 11 into a digital signal for comparison at a required sample time and quantization level. Reference numeral 21 denotes, for example, an amplifier for B signals, which amplifies the input signal by changing the gain,
The amplifier 21 is provided with an adjustment operation unit 22 for adjusting the gain, for example, a variable volume or the like. 24 is the amplifier 2
The third A / D conversion unit converts the G output signal of No. 1 into a digital signal at a required sample time and a required quantization level. Reference numeral 25 is a second adjusting unit for adjusting the magnitude of the digital signal for the comparison reference. Reference numeral 17 is a second comparison unit that compares the output of the third A / D conversion unit 24 and the output of the second adjustment unit 25. 18 is the second comparison unit 1
7 is a second display unit configured to display the comparison result of No. 7 and including, for example, an LED.

The operation of the white balance adjusting circuit according to the present invention will be described. In FIG. 1, for example, when adjusting the white balance of a television, a video signal of a reference white signal is supplied to a signal processing circuit (not shown), and as a result of the processing of the signal processing circuit,
The R, G, and B primary color signals are generated and output (white balance adjustment state). For example, when the R, G, and B primary color signals are supplied to the amplifier 1, the amplifier 11, and the amplifier 21, respectively, the G primary color signal is used as a comparison reference and the adjustment operation unit 12 of the amplifier 11, for example, a variable volume is operated. Then, adjust the gain to match the predetermined position, and set the second A / D
The conversion unit 14 generates a digital signal. On the other hand, the R primary color signal that has passed through the R signal amplifier 1 is converted into a digital signal by the first A / D conversion unit 4 and applied to one input terminal of the first comparison unit 7. In addition, the other input terminal of the first comparison unit 7 is a comparison reference generated by the second A / D conversion unit 14 and adjusted to a required size by the first adjustment unit 5. Is being applied. The first comparison unit 7 compares the digital signal of the R signal with the digital signal of the G primary color signal adjusted to a required magnitude, and when the magnitudes of the two signals match, a high signal is detected. The LED of the first display portion 8 is configured to be turned on by the output of the same signal. Therefore, the adjustment operation unit 2 of the amplifier 1
Adjust the gain so that the display lights up by operating the variable volume control of. Further, for the B signal, the same gain adjustment is performed so that the corresponding display lights up. Depending on the display device, the light emission efficiencies of the R, G, and B primary color signals may be the same. In that case, the primary color signals are directly compared without providing the first adjusting unit 5 and the first adjusting unit 25. You may do it.

FIG. 2 is a block diagram of another embodiment of the white balance adjusting circuit according to the present invention. The same parts as those in the embodiment of FIG. 1 are designated by the same reference numerals, and the duplicated description will be omitted. 9 is
The digital signal of the R primary color signal, which is the output of the first A / D conversion unit 4, and the second A / D conversion unit 14 output
It is a first subtraction unit for calculating the difference between the G primary color signal and the reference digital signal. 29 is a digital signal of the B primary color signal, which is the output of the third A / D conversion unit 24, and the second A
The second subtraction unit calculates the difference between the G primary color signal and the reference digital signal output from the / D conversion unit 14. 6, 1
6, 26 are the amplifier 1, the amplifier 11, and the amplifier 21.
, A first D / A conversion unit that supplies an analog gain adjustment signal obtained by converting the control data, a second D / A conversion unit, and a third D
/ A conversion unit. 30 is the control data for the first D / A
Reference numeral 31 denotes a first control unit that supplies the conversion unit, 31 denotes a second control unit that supplies control data to the second D / A conversion unit,
A third control unit 32 supplies control data to the third D / A conversion unit. Reference numeral 33 is a first memory for storing control data corresponding to the difference value in a lookup table format, 34 is a second memory for storing control data in the lookup table format, and 35 is control data corresponding to the difference value. Is a third memory for storing in a lookup table format.

The operation of the white balance adjusting circuit of this embodiment will be described. First, as in the above-described embodiment, the white balance adjustment state is set. The first subtraction unit 9 is a digital signal of the R primary color signal output from the first A / D conversion unit 4 and a reference digital of the G primary color signal output from the second A / D conversion unit 14. The difference with the signal is calculated, and the difference is calculated by the first control unit 30.
The control unit 30 reads the control data corresponding to the difference value from the control data stored in advance in the look-up table format in the first memory 33, and the first D / A conversion unit 6 The first D / A converter 6 converts the supplied control data into a corresponding analog signal, feedback-controls the gain of the amplifier 1, and calculates the difference between the R primary color signal and the G primary color signal. Control to be the size of. The second subtraction unit 29 outputs the digital signal of the B primary color signal output from the third A / D conversion unit 24 and the reference digital signal of the G primary color signal output from the second A / D conversion unit 14. The difference from the signal is calculated, and the difference is supplied to the third control unit 32. The control unit 32 selects the difference value from the control data stored in the third memory 35 in the look-up table format in advance. Read the control data corresponding to the third D / A conversion unit 2
6, the third D / A converter 6 converts the supplied control data into a corresponding analog signal, and the amplifier 21
The gain is controlled by feedback so that the difference between the B primary color signal and the G primary color signal becomes a required magnitude. Second control unit 31
Reads out predetermined control data from the second memory 34,
The control data is supplied to the second D / A conversion unit 16, and the conversion unit 16 converts the control data into an analog control signal and supplies the analog control signal to the amplifier 11 that amplifies the G primary color signal.
Depending on the display device, the light emission efficiencies of the R, G, and B primary color signals may be the same, and in that case, since one type of lookup table is sufficient, the first control unit 30 and
The first memory 33, the third controller 32, and the third memory 3
5 may be integrated into one control unit and one memory. When the brightness of the supplied white video signal is adjusted to make the amplification rate of the G primary color signal constant, the amplifier 11 has a fixed gain, the second control unit 31, the second memory 34, and the The second D / A converter 16 may be unnecessary.

[0010]

As described above, the present invention provides a white balance adjusting circuit which can be easily adjusted without using a measuring instrument such as an oscilloscope. Therefore, from the white balance adjustment process of the factory, there is an advantage that specialized adjustment techniques such as operating an oscilloscope and observing the waveform are not required and the adjustment can be simplified.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a white balance adjusting circuit according to the present invention.

FIG. 2 is a block diagram of another embodiment of the white balance adjusting circuit according to the present invention.

FIG. 3 is a block diagram of an embodiment of a conventional white balance adjustment circuit.

[Explanation of symbols]

 1 Amplifier 2 Adjustment Operation Section 3 Picture Tube 4 First A / D Conversion Section 5 First Adjustment Section 6 First D / A Conversion Section 7 First Comparison Section 8 First Display Section 9 First Subtraction Section 11 Amplifier 12 Adjustment operation part 14 Second A / D conversion part 16 Second D / A conversion part 17 Second comparison part 18 Second display part 21 Amplifier 22 Adjustment operation part 24 Third A / D conversion part 25 Second Adjustment unit 26 third D / A conversion unit 29 second subtraction unit 30 first control unit 31 second control unit 32 third control unit 33 first memory 34 second memory 35 third memory 40 oscilloscope 41 adjuster

Claims (5)

[Claims] 1. A white balance adjusting circuit comprising an amplifier for changing the gain for each of the R, G, B primary color signals for amplification, and an adjusting operation section for adjusting the gain for each of the amplifiers. A first A / D converter, which converts each output signal into a digital signal at a required sample time and quantization level, a second A / D converter, and a third A / D.
A conversion unit and a first comparison unit in which any one of the three A / D conversion units is used as a reference signal input and the other two digital signals are used as comparison signal inputs, and a second comparison unit. Section, a first display section that displays the comparison result of the first comparison section, and a second display section that displays the comparison result of the second comparison section. 2. A first adjusting unit for adjusting the magnitude of the reference signal input and supplying it to the first comparing unit, and a first adjusting unit for adjusting the magnitude of the reference signal input and supplying it to the first comparing unit. 2. The white balance adjusting circuit according to claim 1, further comprising: 3. A white balance adjustment circuit comprising an amplifier for changing and amplifying each of R, G, B primary color signals and an adjusting section for adjusting the gain for each of the same, and a white balance adjusting circuit for each output of the amplifier. A first A / D conversion unit, a second A / D conversion unit, and a third A / D converter that are provided to convert each output signal into a digital signal at a required sample time and quantization level.
A digital signal output by the conversion unit and any one of the three A / D conversion units is used as one signal input, and digital signals output by the other two A / D conversion units are used as other signal inputs. A first subtraction unit that subtracts two signal inputs from each other to obtain a difference value, a second subtraction unit, and a first memory that stores control data corresponding to the difference value in a lookup table format. A third memory, a first control unit for reading control data from the first memory based on a difference value generated by the first subtraction unit, and converting the control data into an analog signal,
A first D / A converter for supplying to a corresponding amplifier, a third controller for reading control data from the third memory based on the difference value generated by the second subtractor, and an analog signal for the control data. A white balance adjustment circuit configured with a third D / A conversion unit that converts the light into a corresponding amplifier and supplies it to a corresponding amplifier. 4. A second memory for storing control data, a second control section for reading required control data from the second memory, and the control data converted into an analog signal and supplied to a corresponding amplifier. The white balance adjusting circuit according to claim 2, further comprising a second D / A converter. 5. The first memory and the third memory are integrated, and the first control unit and the third control unit are integrated, and each is configured by one memory and one control unit. The white balance adjusting circuit according to claim 2.