JP2000115802A - Display device white balance adjustment circuit - Google Patents

Abstract

(57) Abstract: To automatically adjust the white balance of a display panel (for example, PDP 20) to an appropriate range even if R, G, and B phosphors deteriorate due to use. SOLUTION: A control data storage ROM 26 preliminarily storing gain control data for R, G, B corresponding to a plurality of stages of cumulative operation times of the PDP 20, a timer 22 for measuring the cumulative operation time T of the PDP 20, a cumulative measurement value It is determined to which one of the accumulated operating times T belongs, and the corresponding gain control data for R, G, B is stored in the control data storage ROM 2.
6 for controlling the gain of the R, G, B amplifiers 10r to 10b via the D / A converters 30r to 30b.
U28, and R, G, B gain control data for correcting the deterioration corresponding to the accumulated use time of the R, G, B phosphors is stored in the control data storage ROM 26 in advance, so that R , G, B phosphors can be automatically and appropriately corrected for white balance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to analog R, G, and B amplifiers each of which can be individually controlled.
The R, G, and B phosphors of the display panel emit light based on (red), G (green), and B (blue) signals, or based on digital R, G, and B signals gamma-corrected by a gamma correction circuit. And a white balance adjusting circuit of a display device for displaying a color image.

[0002]

2. Description of the Related Art Heretofore, white balance adjustment of a display device of this type has only been performed before shipment from a factory. Generally, the deterioration (change in luminous efficiency) of the phosphor differs depending on the type of the phosphor, and thus the degree of deterioration of the R, G, and B phosphors of the display panel with respect to the usage time also differs from one another. For this reason, even if the white balance is correctly adjusted at the time of shipment, the white balance may be lost over time. For example, when the B phosphor deteriorates faster than the R and G phosphors (generally, in many cases), a problem has occurred in that a white portion of a color image changes to a yellowish color tone. Conventionally, when correcting such white balance collapse, the white balance is readjusted by manual adjustment.

[0003]

As described above, since the white balance adjustment of the conventional display device is performed only before shipment, if the white balance is not readjusted after shipment, the white balance is adjusted with the lapse of time. There has been a problem that the white balance has been lost and the white part of the color image has a yellowish tone. Further, since the readjustment of the white balance has been performed manually, there has been a problem in that manual adjustment is required and the operation becomes complicated.

The present invention has been made in view of the above-mentioned problems, and based on the knowledge that the degree of deterioration of the R, G, and B phosphors can be estimated based on the use time, white light is automatically obtained even after shipment. It is an object of the present invention to provide a white balance adjustment circuit of a display device capable of adjusting the balance.

[0005]

According to a first aspect of the present invention, the R, G, and B signals of a display panel are based on analog R, G, and B signals individually amplified by gain-controllable R, G, and B amplifiers. In a display device which emits a B phosphor to display a color image, a storage means in which R, G, and B gain control data corresponding to a plurality of cumulative operation times of the display panel are stored in advance, and the cumulative operation of the display panel A measuring means for measuring time, and determining to which of a plurality of stages of accumulated operating time the measured value of the measuring means belongs to the storage means, and from the storage means the corresponding R, G, B Control means for reading the gain control data and controlling the gains of the R, G, and B amplifiers.

[0006] The cumulative value of the operating time of the display panel for displaying a color image by emitting R, G, B phosphors is counted by the measuring means, and the measured value is stored in the storage means in a plurality of stages of the cumulative operating time. , And the corresponding gain control data for R, G, and B are read out, and the gains of the R, G, and B amplifiers are individually controlled.
The white balance adjustment after shipment is automatically performed by storing in advance the gain control data for R, G, and B for correcting the deterioration due to the cumulative use time of the R, G, and B phosphors in the storage unit. be able to.

According to a second aspect of the present invention, in order to prevent a change in luminance of a color image during white balance adjustment from giving a strange feeling to a person in the first aspect of the present invention, R, G,. The gain control data for B is set to 1
The amount of change per stage is set below the set value.

According to a third aspect of the present invention, there is provided a display device for displaying a color image by emitting R, G, B phosphors of a display panel based on digital R, G, B signals gamma-corrected by a gamma correction circuit. A storage means for storing in advance the gamma correction data for R, G, B used in the gamma correction circuit in correspondence with the cumulative operation time of a plurality of stages of the display panel; a measuring means for measuring the cumulative operation time of the display panel; The gamma correction for the R, G, and B corresponding to the gamma correction data used in the gamma correction circuit is determined by determining to which of the cumulative operation times of the plurality of stages the measured value of the measuring means belongs. Control means for switching to data.

[0009] The cumulative value of the operating time of the display panel for displaying the color image by emitting the R, G, B phosphors is counted by the measuring means, and the measured value is stored in the storage means in a plurality of stages of the cumulative operating time. Based on which stage of
Since the gamma correction data used in the gamma correction circuit is controlled to the corresponding gamma correction data for R, G, and B,
By storing in advance the gamma correction data for R, G, and B for correcting the deterioration due to the cumulative use time of the G and B phosphors, the white balance can be automatically adjusted after shipment. it can.

According to a fourth aspect of the present invention, in order to prevent a change in luminance of a color image at the time of white balance adjustment from giving a strange feeling to a person, the R, G,. The gamma correction data for B is accumulated operation time 1
The amount of change per stage is set below the set value.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a white balance adjusting circuit of a display device according to the present invention will be described with reference to FIG. In FIG. 1, reference numerals 10r, 10g, and 10b denote input terminals for inputting analog R (red), G (green), and B (blue) signals. Each of the input terminals 10r, 10g, and 10b has an individual gain. Controllable R, G, B amplifier 12
A / D (analog / digital) converters 14r, 14g, 14b are coupled via r, 12g, 12b.
A PDP (plasma display panel) 20 is connected to the output sides of the A / D converters 14r, 14g, and 14b via a pixel conversion processing circuit 16 and an image quality correction processing circuit 18.

Reference numeral 22 denotes a timer for measuring the operation time of the PDP 20, and reference numeral 24 denotes a cumulative measured value memory for storing the cumulative value of the measured value of the timer 22. Reference numeral 26 denotes a control data storage ROM (read only memory) which stores the R, G,
For each of the B phosphors, R, G, and B gain control data corresponding to a plurality of stages of cumulative operation times are stored in advance. These R, G, and B gain control data are determined based on experimental data and theoretical data in order to correct the deterioration of the R, G, and B phosphors due to the cumulative operating time (actual use time). . At this time, the number of stages for dividing the cumulative operation time is set so that the amount of change in each stage of the gain control data is equal to or less than a set value and the luminance change does not give a strange feeling to a person. For example, assuming that the desired characteristic of the amplification degree gr of the R amplifier 14r for correcting the luminance decrease due to the deterioration of the R phosphor is a characteristic shown by a dotted line in FIG. The number of steps (for example, 256 steps) is set so as to be S or less (only the first four steps are displayed in FIG. 2 for convenience of illustration). In FIG. 2, the cumulative operation time T0
≦ T <T1, T1 ≦ T <T2, T2 ≦ T <T3,..., T0, T1, T2, T3 are, for example, 0 hours,
It is set to 100 hours, 200 hours, and 300 hours.

Reference numeral 28 denotes an MPU (microprocessor unit). The MPU 28 is an RO storing a program.
M and a RAM (random access memory) as a main storage unit, and have the following functions. A function for setting the timer 22 when the power is supplied to the PDP 20 (when the power is turned on), counting the clock by the timer 22, and measuring the operation time. When the power to the PDP 20 is cut off (when the power is turned off), the measured value of the timer 22 is stored in the cumulative measured value memory 24 in the cumulative measured value memory 24.
And the timer 22 is reset. The cumulative measured value T in the cumulative measured value memory 24 is stored in a plurality of stages of cumulative operating times (for example, T0 ≦ T <T1, T1 ≦ T <T2, T2 ≦ T) in the control data storage ROM 26.
<T3,...), The corresponding gain control data for R, G, B is read out.
(Digital / analog) converter 30r, 3
Function to output to 0g and 30b. With this function, R,
The G and B gain control data are supplied to the D / A converters 30r and 30r.
g, 30b, is converted into an analog signal, and is input to the control terminals of the R, G, B amplifiers 12r, 12g, 12b, and the amplification degrees of the R, G, B amplifiers 12r, 12g, 12b correspond to the corresponding values gr, gg. , Gb.

Next, the operation of the embodiment of FIG. 1 will be described with reference to FIG. For convenience of explanation, control data storage RO
The gain control data for R stored in advance in M26 is stored in a plurality of stages of cumulative operation times T0 ≦ T <T1, T1 ≦ T <T2,
GDr0, GDr1, G corresponding to T2 ≦ T <T3,.
, And these gain control data GDr0, G
The amplification degree of the R amplifier 12r is Gr with Dr1, GDr2,.
0, gr1, gr2,... Similarly, the gain control data for G and B stored in the control data storage ROM 26 in advance is expressed as T0 ≦ T <T1, T1 ≦ T
GDg0, GD corresponding to <T2, T2 ≦ T <T3,...
g1, GDg2,..., GDb0, GDb1, GDb2,
, And G and B amplifiers 1 based on these gain control data.
The amplification degrees of 2g and 12b are gg0, gg1, gg2,.
gb0, gb1, gb2,...

(A) In the initial state, since the cumulative measurement value T in the cumulative measurement value memory 24 is 0, the corresponding gain control data GDr0, GDg0, GDb0 in the control data storage ROM 26 is read out by the function of the MPU 28. , D / A converters 30r, 30g, and 30b, and are converted into analog signals, and the R, G, and B amplifiers 12r, 12g, and 12
b is input to the control terminal. Therefore, the input terminal 10r,
Analog R, G, and B signals input to 10g and 10b are converted into gr0, g by amplifiers 12r, 12g, and 12b.
Amplified at the amplification degree of g0 and gb0,
The digital signal is converted into digital signals by r, 14g, and 14b, resampled by the pixel conversion processing circuit 16 so as to match the number of pixels of the PDP 20, image quality correction processing (for example, gamma correction processing) by the image quality correction processing circuit 18, and The image is displayed. For example, for the R signal, the gain control data GDr0 is input to the control terminal of the R amplifier 12r, and the amplification degree of the R amplifier 12r becomes gr as shown in FIG.
It becomes 0.

(B) When power is supplied to the PDP 20 by turning on the power, the timer 22 is set by the function of the MPU 28, and the timer 22 counts a clock to
The operation time of P20 is measured. When the power supply to the PDP 20 is cut off by turning off the power, the measurement value of the timer 22 is cumulatively added to the measurement value in the cumulative measurement value memory 26 by the function of the MPU 28 and the timer 22 is reset. Therefore, the cumulative operation time of the PDP 20 is stored in the cumulative measurement value memory 24 as the cumulative measurement value T.
Until the cumulative operation time of the PDP 20 reaches T1 (T0 ≦
T <T1), the amplification degree of the amplifiers 12r, 12g, and 12b remains at gr0, gg0, and gb0, but the PDP 20
When the cumulative operation time of TPU reaches T1 (T = T1), the MPU
The gain control data read from the control data storage ROM 26 by the function 28 is GDr0, GDg0, GDr0.
The state changes from b0 to GDr1, GDg1, and GDb1. Therefore, the amplification of the R, G, B amplifiers 12r, 12g, 12b is increased from gr0, gg0, gb0 to gr1, gg1, g.
b1, and a decrease in luminance due to deterioration of the R, G, and B phosphors of the PDP 20 based on the cumulative operation time T (T1 ≦ T <T2) is corrected. For example, for the R signal, the gain control data GDr1 is input to the control terminal of the R amplifier 12r, and the amplification degree of the R amplifier 12r becomes gr0 as shown in FIG.
To gr1, and a decrease in luminance due to deterioration of the R phosphor is corrected.

(C) Similarly, the cumulative measurement value T in the cumulative measurement value memory 24 is changed by the function of the MPU 28 to the cumulative operation time T1 ≦ T <in the control data storage ROM 26.
It is determined which of T2, T2 ≦ T <T3,..., And the amplification degrees of the amplifiers 12r to 12b are gr1 to gb1,
gr2 to gb2,..., PDP based on cumulative operation
The luminance reduction due to the deterioration of the R, G, and B phosphors of No. 20 is corrected. For example, for the R signal, when the gain control data GDr2 and GDr3 are input to the control terminal of the R amplifier 12r, the amplification of the R amplifier 12r becomes gr2 and gr3 as shown in FIG. , The amount of decrease in luminance due to this is corrected.

FIG. 3 shows another embodiment of the present invention, in which the same parts as those in FIG. 1 are designated by the same reference numerals.
In FIG. 3, reference numerals 10r, 10g, and 10b denote input terminals for inputting analog R, G, and B signals.
An A / D converter 14 is provided for each of 0r, 10g, and 10b.
r, 14g and 14b are combined, and this A / D converter 14
r, 14g, 14b, the pixel conversion processing circuit 1
6. The PDP 20 is coupled via the gamma correction processing circuit 40 and the halftone processing circuit 42.

The gamma correction processing circuit 40 is connected to a gamma correction ROM 44 as storage means.
R, G, and R corresponding to a plurality of stages of cumulative operating times for each of the R, G, and B phosphors of the PDP 20.
Gamma correction data for B is stored in advance. These gamma correction data for R, G, and B are determined based on experimental data and theoretical data in order to correct the deterioration of the R, G, and B phosphors due to the cumulative operating time. For example,
The gamma correction data for the B phosphor is based on the cumulative operation times T0 ≦ T <T1, T1 ≦ T <T2, and T2 ≦ T shown in FIG.
<Gamma correction curves γB0, γB1,
If the data satisfies γB2,.
The OM 44 has a cumulative operation time T0 ≦ T <T1, T1 ≦ T
Data tables DTb0, DTb1, DTb2, DTb3,... Corresponding to <T2, T2 ≦ T <T3,.
2, DTb3,... Include gamma correction curves γB0,
Data satisfying γB1, γB2,... are stored in advance. At this time, the number of stages for dividing the cumulative operation time is such that the amount of change in each stage of the gamma correction data is equal to or less than the set value,
The brightness change is set so as not to give a strange feeling to a person.

Reference numeral 22 denotes a timer for measuring the operation time of the PDP 20, and reference numeral 24 denotes a cumulative measured value memory for storing the cumulative value of the measured value of the timer 22. 46 is MP
U (microprocessor unit), this MPU 46
Is a ROM storing a program and R as a main storage unit.
It has an AM (random access memory) and has the following functions. A function that sets the timer 22 when the power is supplied to the PDP 20 (when the power is turned on) and causes the timer 22 to count the clock to measure the operation time. The function of accumulating the measured value of the timer 22 to the accumulated measured value in the accumulated measured value memory 24 and resetting the timer 22 when the power to the PDP 20 is cut off (when the power is turned off). The cumulative measured value T in the cumulative measured value memory 24 is γ corrected RO
Multi-stage cumulative operation time T0 ≦ T set in M44
A function of determining which of <T1, T1 ≦ T <T2, T2 ≦ T <T3,..., And selecting the corresponding R, G, B gamma correction data.

Next, the operation of the embodiment of FIG. 3 will be described with reference to FIG. For convenience of explanation, the gamma correction data for R, which is stored in advance in the gamma correction ROM 44, is stored in a plurality of stages of cumulative operation times T0 ≦ T <T1, T1 ≦ T <T2, T2
Data tables DTr0, D corresponding to ≦ T <T3,.
Data of Tr1, DTr2,... Similarly, γ
The gamma correction data for G and B stored in advance in the correction ROM 44 is defined as T0 ≦ T <T1, T1 ≦ T <T2, T2 ≦
DTg0, DTg1, DTg corresponding to T <T3,.
, DTb0, DTb1, DTb2,... For example, the cumulative operation time T0 ≦ T <T1, T1 ≦ T <T for correcting the deterioration of the B phosphor of the PDP 20.
2, gamma correction data corresponding to T2 ≦ T <T3 and T3 ≦ TB <T4 are obtained by using gamma correction curves γB0 and γB in FIG.
Data table DTr satisfying 1, γB2, γB3
0, DTr1, DTr2, and DTr3.

(A) In the initial state, since the cumulative measurement value T in the cumulative measurement value memory 24 is 0, the gamma correction in the data tables DTr0, DTg0, and DTb0 corresponding to T0 in the gamma correction ROM 44 is performed by the function of the MPU 46. The data is selected. For example, for the B phosphor of the PDP 20, gamma correction data on the data table DTr0 that satisfies the gamma correction curve γB0 shown in FIG. 4 is selected. Therefore, the analog R, G, and B signals input to the input terminals 10r, 10g, and 10b are input to the A / D converter 1
4r, 14g, and 14b, are converted into digital signals, are resampled by the pixel conversion processing circuit 16 so as to match the number of pixels of the PDP 20, and are subjected to the γ correction RO by the γ correction processing circuit 40.
Data table DTr0, DTg0, DTb in M44
Gamma correction processing using gamma correction data on 0 is performed, halftone processing (for example, error diffusion processing) is performed by the halftone processing circuit 42, and a color image is displayed on the PDP 20.

(B) When power is supplied to the PDP 20 when the power is turned on, the timer 22 is set by the function of the MPU 46,
The operation time of P20 is measured. When the power supply to the PDP 20 is cut off by turning off the power, the measured value of the timer 22 is cumulatively added to the measured value in the cumulative measured value memory 24 by the function of the MPU 46 and the timer 22 is reset. Therefore, the cumulative operation time of the PDP 20 is stored in the cumulative measurement value memory 24 as the cumulative measurement value T.
Until the cumulative operation time of the PDP 20 reaches T1 (T0 ≦
T <T1) is determined by the function of the
Corresponding data tables DTr0, DTg in M44
0 and DTb0 are selected, and the gamma correction processing circuit 40 performs gamma correction processing.
When the cumulative operating time of 0 reaches T1 (T = T1), MP
By the function of U46, the data table in the gamma correction ROM 44 is changed from DTr0, DTg0, DTb0 to DTr1,
Switching is performed between DTg1 and DTb1, and the gamma correction processing circuit 40 performs gamma correction using the gamma correction data on the data tables DTr1, DTg1, and DTb1. For this reason, the input / output conversion rate by the gamma correction of the gamma correction processing circuit 40 increases from the initial state, and the cumulative operation time T1
The reduction in luminance due to the deterioration of the R, G, and B phosphors of the PDP 20 based on ≦ T <T2 is corrected.

(C) Hereinafter, similarly, the cumulative operation value T in the cumulative measurement value memory 24 is stored in the gamma correction ROM 44 by the function of the MPU 46 in a plurality of stages of cumulative operation times T1 ≦ T <T2, T2 ≦ T <T3,..., And the corresponding R, G, B data table D
Tr1 to DTb1, DTr2 to DTb2,.
These data tables DTr1-DTb1, DTr2
.. DTb2,... Γ correction processing circuit 40 performs gamma correction using the above gamma correction data. For this reason, the input / output conversion rate by the gamma correction of the gamma correction processing circuit 40 increases corresponding to the cumulative operation time T1 ≦ T <T2, T2 ≦ T <T3,..., And the R, G, B phosphors of the PDP 20 The decrease in luminance due to deterioration is corrected. For example, for the B phosphor of the PDP 20, the gamma correction curve shown in FIG. 4 switches from γB0 to γB1, γB2,.
The input / output conversion rate due to the gamma correction of
The decrease in luminance due to the deterioration of the phosphor is corrected.

In the above embodiment, the timer is set when the power is turned on and is reset when the power is turned off. However, the present invention is not limited to this. It can also be used for a configuration that measures in this case,
The accumulated measured value memory can be omitted.

In the above-described embodiment, the case where the display panel is a PDP (that is, the case where the degree of deterioration of the phosphor over time is large, which is considered to be highly useful in the present invention) has been described. The present invention is not limited to this, and can be used even when the display panel is an LCD or a CRT (cathode ray tube).

[0027]

According to the first aspect of the present invention, as described above, the storage means in which the gain control data for R, G, and B corresponding to the cumulative operation time of the display panel in a plurality of stages is stored in advance, and the accumulation of the display panel is performed. A measuring means for measuring the operating time, and determining to which of the plurality of cumulative operating times the measured value of the measuring means belongs to the storage means, the corresponding R, G, B from the storage means Control means for reading the gain control data for use and controlling the gains of the R, G, and B amplifiers, and controlling the gains of the R, G, and B amplifiers in accordance with the cumulative operation time of the display panel. By storing in advance the R, G, B gain control data for correcting the deterioration due to the cumulative use of the R, G, B phosphors in the storage means, the white balance adjustment after the display device is shipped. It can be carried out automatically.

According to a second aspect of the present invention, in the first aspect of the present invention, the amount of change in the cumulative operating time per one step of the gain control data for R, G, and B stored in the storage means is equal to or less than a set value. With such a setting, it is possible to prevent a change in luminance for white balance adjustment from giving a strange feeling to a person.

According to a third aspect of the present invention, there is provided a storage means in which gamma correction data for R, G, and B used in a gamma correction circuit are stored in advance in correspondence with a plurality of stages of cumulative operation times of the display panel, The measuring means for measuring the time and the gamma correction data used in the gamma correction circuit corresponding to which stage of the cumulative operation time of the plurality of stages the measurement value of the measuring means belongs to are determined. Control means for switching to gamma correction data for R, G, and B. The gamma correction data used in the gamma correction circuit is switched according to the cumulative operation time of the display panel. By storing in advance the gamma correction data for R, G, and B for correcting the deterioration due to the storage in the storage unit, the display device can be shipped. White balance adjusting can be performed automatically in.

According to a fourth aspect of the present invention, in the third aspect of the invention, the gamma correction data for R, G, and B stored in advance in the storage means is such that the amount of change per one stage of the cumulative operation time is equal to or less than a set value. , It is possible to prevent a change in luminance for white balance adjustment from giving a strange feeling to a person.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a white balance adjustment circuit of a display device according to the present invention.

FIG. 2 is a graph showing the cumulative operating time (T0) of the R amplifier 10r of FIG. 1;
FIG. 9 is a characteristic diagram showing a relationship of amplification degree gr (gr0, gr1, gr2,...) With respect to ≦ T <T1, T1 ≦ T <T2, T2 ≦ T <T3,.

FIG. 3 is a block diagram showing another embodiment of the white balance adjustment circuit of the display device according to the present invention.

FIG. 4 is a diagram showing R and R stored in a γ-ROM 44 of FIG.
The cumulative operation time (T0 ≦ T <T1, Tg) for the gamma correction data for B among the gamma correction data for G and B
FIG. 9 is a characteristic diagram illustrating gamma correction curves (γB0, γB1, γB2,...) Corresponding to 1 ≦ T <T2, T2 ≦ T <T3,.

[Explanation of symbols]

10r, 10g, 10b ... R, G, B signal input terminals,
12r, 12g, 12b ... R, G, B amplifiers, 14
r, 14g, 14b A / D converters for R, G, B,
16: pixel conversion processing circuit, 18: image quality correction processing circuit,
20 ... PDP (an example of a display panel), 22
... Timer, 24 ... Cumulative measured value memory, 26 ... Control data storage ROM, 28, 46 ... MPU, 30r,
30g, 30b ... D / A converters for R, G, B, 40
.... gamma. Correction processing circuit 42... Halftone processing circuit 44.
γ correction ROM, gr... amplification degree of R amplifier 12r,
gr0, gr1, gr2, gr3... cumulative operation time T0 ≦
T <T1, T1 ≦ T <T2, T2 ≦ T <T3, T3 ≦ T
<Amplification degree of R amplifier 12r by gain control data GDr0 to GDr3 corresponding to T4, T: cumulative operation time,
γB0, γB1, γB2, γB3 ... cumulative operation time T0
≦ T <T1, T1 ≦ T <T2, T2 ≦ T <T3, T3 ≦
Gamma correction curve corresponding to T <T4.

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 5C066 AA03 BA20 CA08 CA13 CA17 DC06 EA03 EA15 EC05 GA01 GB01 HA03 KA01 KD06 KE07 KE09 KE17 KE19 KE20 KE24 KH01 KM12 KM13 LA02 5C080 AA05 BB05 CC03 DD29 DD30 GG12 JJ02 JJ04 JJ05

Claims (4)

[Claims] 1. A color image is displayed by emitting R, G, and B phosphors of a display panel based on analog R, G, and B signals individually amplified by gain-controllable R, G, and B amplifiers. R, G, and G corresponding to the accumulated operation time of the display panel in a plurality of stages.
Storage means for previously storing gain control data for B; measuring means for measuring the cumulative operation time of the display panel; and a measurement value of the measurement means among the cumulative operating times of a plurality of stages stored in the storage means. Control means for judging to which stage the gain belongs, reading corresponding gain control data for R, G, B from the storage means and controlling the gains of the R, G, B amplifiers. White balance adjustment circuit of the display device. 2. The display device according to claim 1, wherein the gain control data for R, G, and B stored in advance in the storage means is such that the amount of change per one step of the accumulated operation time is set to a set value or less. Balance adjustment circuit. 3. A display apparatus for displaying a color image by emitting R, G, B phosphors of a display panel based on digital R, G, B signals gamma-corrected by a gamma correction circuit. Storage means for storing in advance the gamma correction data for R, G, B used in the circuit in correspondence with the cumulative operation time of the display panel in a plurality of stages; measuring means for measuring the cumulative operation time of the display panel; The gamma correction for the R, G, and B corresponding to the gamma correction data used in the gamma correction circuit is determined by determining to which stage the measured value of the means belongs to the cumulative operation time of the plurality of stages stored in the storage means. A white balance adjustment circuit for a display device, comprising: control means for switching to data. 4. The display device according to claim 3, wherein the gamma correction data for R, G and B stored in advance in the storage means is such that the amount of change per one step of the accumulated operation time is set to a set value or less. Balance adjustment circuit.