JP2001350442A - Driving method for display panel, luminance correcting device and driving device for display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the conventional system is inconvenient in workability for the user of a picture display device, since it is necessary to interrupt the displaying of a video in the course of video displaying in order to perform correction in the conventional luminance correction system of a display. SOLUTION: In this driving system of a display panel, the display having no unevenness of light emission with respect to both of an initial characteristics and a secular characteristics is realized by preparing a luminance correction memory while measuring anode currents of an FED(field emission display). Moreover, the secular change can be corrected without interrupting the outputting of the video by capturing luminance information of pixels while lighting arbitrary pixels in a video inactive period and updating the correction memory based on the luminance information. Thus, a display panel maintains high display quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a light-emitting device such as an electron-emitting device and an organic EL device, and to a display device using a plurality of the above-mentioned light-emitting devices. The present invention relates to a method of correcting and driving a luminance, a luminance correction device thereof, and a driving device using the same.

[0002]

2. Description of the Related Art (First Background Art) FIG. 46 shows a configuration of a display device using a conventional electron-emitting device or the like. In FIG. 46, reference numeral 509 denotes a matrix display panel in which a plurality of signal lines and a plurality of scanning lines are combined, 507 denotes a signal driver for driving the signal lines, 508 denotes a scanning driver for driving the scanning lines, and 502 denotes a signal driver. A controller that controls the driver 507 and the scanning driver 508. At the time of gradation driving, data corresponding to the image signal is input to the signal driver 507, and the signal driver 5
07 is provided with a gradation control function.

Conventionally, two methods have been used for this gradation control method. First, time width modulation (hereinafter abbreviated as PWM) will be described. An example of the configuration of a signal driver according to this method is shown in FIG. 47 and will be described with reference to the drawing. In FIG. 47, reference numeral 540 denotes a shift register (abbreviated as SR) which determines timing for sampling a data signal from a clock and a start signal from a controller. Reference numeral 541 denotes a latch which connects a plurality of signal data lines indicating gradations to S.T. R. And latches temporary data according to the output timing. A decoder 542 determines the PWM output timing based on the data stored in the latch 541, and outputs the output pulse-width-modulated last by the PWM circuit 560 to the signal line of the display panel. FIG. 48 shows an example of the output. The gray scale display is performed by controlling the time width from 100% to the LSB output of the minimum unit in accordance with the gray scale at which a constant output is desired to be displayed every one horizontal period in synchronization with the driving of the scanning line.

FIG. 49 shows a configuration example of another signal driver of the output amplitude modulation system, which will be described with reference to the drawing. FIG.
Those having the same functions as those described above are denoted by the same reference numerals and description thereof will be omitted. 5
A D / A circuit 43 converts data stored in the latch 541 into an analog voltage, and inputs the output to an amplifier. A voltage corresponding to the output voltage of the D / A 543 is applied to the panel signal line, and gradation display is performed by voltage amplitude modulation according to the data signal. FIG. 50 shows an example of the output. Over a valid scanning period in one horizontal period, a constant current is driven from 100% to the minimum unit LSB to display a gray scale.

[0005] Among the conventional examples described above, with respect to PWM, there is a disadvantage that as the number of gray scale displays increases, the LSB of the minimum unit becomes narrower, and a high-speed operation is required as a signal driver. For example, in consideration of 8 bits and 256 gradations required for a natural image in a 640 × 480 display panel for a computer, if the frame unit is 60 frames / sec, the LSB width becomes 0.12 μs and the signal width becomes narrow. An extremely strict high-speed operation is required as a driver. Further, in the future, higher resolution is required, and faster response is required. In addition, a capacitance component due to wiring is added, and even if the signal driver operates at high speed, current escapes to the parallel capacitance, and LS
A phenomenon has occurred in which light emission is not performed in B units, and fine gradation expression is impaired.

There is no problem with high-speed operation in the other output amplitude modulation method, but there is a problem that the output deviation of the signal driver becomes severe when the number of gradations is large. For example, 1
8 bit2 with a signal driver that sets 5V at 00% output
The LSB output at the time of 56 gradations is 20 mV, and assuring this accuracy uniformly over all lines becomes costly and industrially strict.

In a display panel in which a plurality of electron-emitting devices are arranged, the electron-emitting characteristics of the respective devices actually vary. This is due to the fact that it is extremely difficult to make the configuration and process of the electron-emitting device the same over all devices, and that the surface state of electron emission is not constant. As a result, even when the same drive voltage is applied to each element, the amount of emission current is different, and there is a problem that uneven brightness occurs.

Further, when the same information is displayed for a long time (for example, a total light emission time of 3000 hours), the element which emits light is more deteriorated than the element which does not emit light. Next, the display of certain information is terminated, and thereafter all the pixels are caused to emit light with the same luminance command (for example, the same current value).
At this time, the pixel where certain information is displayed, where the entire surface should emit light with the same luminance, has a lower luminance than the other elements because the deterioration has progressed. For this reason, there has been a problem that a luminance difference occurs, and certain information that has been displayed up to that point is seen as a burn-in phenomenon.

[0009] Japanese Patent Application Laid-Open No.
There is 5430 gazette. This realizes gradation by combining time width control and amplitude control. In this configuration, the values of pulse width control and amplitude control are added using an adder. At this time, PAM is selected according to the characteristics of the electron-emitting device.
Although the log amplifier is connected to the output of the circuit, if the log amplifier is not connected to the output of the time width control, a problem occurs that the characteristics do not match. In addition, although the characteristics of the electron-emitting device are log characteristics, the actual device characteristics do not exactly fall on a straight line of the log characteristics, and variations occur. For this reason, it is difficult to output a gray scale with high accuracy using only a simple log amplifier. In addition, the configuration of the conventional example has a problem that it cannot cope with a variation in luminance and a change with time when an image is formed.

(Second Background Art) Conventionally, for example, in an image display device in which a large number of electron-emitting devices are formed and arrayed, variations in device characteristics exist, and brightness variations have occurred due to such variations. In various image forming apparatuses, high resolution,
There is a demand for high-quality images, and various driving methods for suppressing variations in luminance have been conventionally proposed.

For example, as a conventional embodiment, Japanese Patent Laid-Open No.
No. 81911. FIG. 51 shows a representative drawing, and the operation is described.

First, a procedure for creating an LUT of correction value data after manufacturing an image forming apparatus will be described. Upon receiving the LUT creation instruction signal, the timing generation circuit 602 generates various timing signals according to the data creation procedure.
In accordance with this signal, the correction data creation circuit 613
/ Driver circuit 609 sends a signal to the SCE element of a specific pixel so as to generate a drive signal of a specific pulse width at a specific drive voltage. The element current If flowing through the SCE element selected by the drive signal and the signal of the scan driver 612 is detected by a current monitor circuit 610 using a monitor resistor, and this output is converted into a digital signal by an AD converter, and a correction data creation circuit 613 is provided. Send to This is performed for all SCE elements. The obtained element current data of each SCE element is stored as current distribution data in a current distribution table in the LUT. Also, focusing on the fact that there is a strong correlation between the electron beam output of the SCE element and the element current If flowing through the element, the following correction method is implemented.

That is, the monitored element current is compared with the element current data stored in the correction data creating section 613 corresponding to the monitored element current, and if it is within a predetermined difference, it is determined to be an appropriate value. If not, it is determined that correction is necessary. If correction is necessary, If correction data for the monitored pixel is created and written to the LUT 606. In the initial state, the If correction data is set to a state where no correction is performed for all pixels. Also, the element current data is set to a predetermined same value for all pixels. When the If correction data is written in the LUT 606 in this manner, the image signal is corrected using the data, and the same element, that is, If, is used again.
The monitoring and determination of the current for the newly set element are repeatedly performed until the correction data reaches an appropriate value.

If it is determined that the element current If has reached an appropriate value, the element current data is updated with the element current at that time. The above processing is performed for all the elements, and the process ends. In this way, the input image signal can be corrected, and the variation in luminance can be corrected.

By repeating the measurement of the current distribution data as described above, it is possible to effectively correct not only the initial characteristic variation of the SCE element but also the characteristic change with time. By performing the above-described driving using the correction values stored in the distribution correction table, it is possible to display a high-quality image with no luminance variation.

In the above-described conventional example, the correction operation for the change over time is as follows. In order to detect a change with time in the element characteristics, the element current If of each element is measured after an appropriate time has elapsed, and compared with the initial value of the element current stored in the current distribution table in the LUT. When the difference between the measured value and the initial value is equal to or greater than a predetermined value, it is determined that the element characteristics have changed with time. Therefore, the same test drive as performed at the beginning is performed, and the correction value in the correction table is changed. Fix it.

At this time, since the correction is performed sequentially for each pixel, a certain time is required, and a problem occurs that the video display must be interrupted during the operation.

For example, if the resolution is VGA (640 × 48
0) It is assumed that a video is displayed by a frame rate of 60 Hz and line-sequential driving. At this time, if the luminance measurement of each pixel is performed in the same cycle as this display operation, the measurement time is
640 × 480 × 1/60 × 1/480 = 10.7 (se
c). Since the correction does not converge below a certain deviation by only one correction, it is necessary to repeat the correction again. For example, if the number of repetitions is 5 and it converges to a certain deviation or less, it takes 54 seconds in total. In order to perform the correction, it is necessary to interrupt the video display halfway, and this time is not ignored or tolerable.

Originally, there is a demand for a display device that does not require a correcting operation. This problem is a problem that the user of the image display device has poor workability and that the quality of the display deteriorates. Become.

(Third Background Art) As a gray scale realizing method, there is a conventional example which employs a gray scale control method for simultaneously performing output amplitude value control and output time width control. However, this conventional example is a method capable of realizing high gradation without requiring high speed and high accuracy. However, a problem may occur in the display at the time of low luminance.

This will be described with reference to FIG. FIG.
(A) is an example in which the time width is divided into 16 and the amplitude value is divided into 4 to realize a total of 64 gradations. At this time, if the elements of the display panel are made of organic EL or the like, and the low luminance side, that is, the gradation value is small and the amplitude value is small, the response speed may be extremely slow (FIG. 52B). It has been confirmed that, for example, in the organic EL element, when a voltage near the threshold is applied and the luminance is low, the response speed is reduced. For this reason, although the restriction on the response speed is eased by reducing the number of divisions of the time width, since the amplitude value (applied voltage) is small, there is a problem that the response speed is further slowed down.

[0022]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a display panel driving method, a display panel luminance correcting apparatus, and a driving method for realizing a display without light emission unevenness with time. It is intended to provide a device.

[0023]

In order to achieve the above object, the present invention employs the following driving method for luminance correction.

The luminance setting reference value is changed with the lapse of time. Thereby, the load on the element can be reduced and the life can be extended.

The update interval of the correction memory is changed according to the luminance degradation characteristics. As a result, re-correction can be performed at optimal intervals without relying on luminance measurement and determination.

For an apparatus having a phosphor, luminance correction is performed in consideration of the degradation characteristics of the phosphor.

The correction operation (driving pixels and taking in luminance information) is performed during a period that does not affect the video signal output. This eliminates the need to interrupt the video display halfway.

In order to realize the gradation, in particular, a method of simultaneously performing the amplitude value control and the time width control, a method of displaying the gradation by changing the amplitude value in the increasing direction, and a control of switching the gradation method And so on. As a result, a high gradation can be realized and a high-quality image can be output.

Hereinafter, a specific configuration of the present invention will be described.

In the display panel driving method according to the present invention, the luminance is set twice or more, and the luminance setting operation is performed such that the respective luminance setting values are different, and the set luminance is changed with the driving time. It is characterized by the following.

According to the above configuration, since the luminance set value when the luminance is re-corrected changes with the driving time, it is possible to prevent the individual elements from being excessively driven, thereby extending the life of the elements. Can be.

The brightness setting value may be determined based on the measured brightness information, and the brightness may be corrected so as to match the determined setting brightness value.

In the present invention, as a specific luminance correction operation, a pixel is driven, luminance information of the pixel is fetched, a correction value is calculated from the measured luminance information and a luminance set value, and the correction value is calculated. The present invention can be applied to a display panel driving method in which the correction value is stored in a memory and the driving amount is corrected according to the correction memory.

It is desirable that the luminance setting value does not exceed the previous luminance setting value.

According to another aspect of the display panel driving method of the present invention, the luminance is corrected at least twice in accordance with a predetermined interval, and the luminance correction operation is performed such that the intervals of the respective luminance correction operations are different. The start interval of the re-correction operation is changed.

With the above configuration, it is possible to secure an optimum correction interval according to the element characteristics.

In particular, it is desirable to change the interval of the luminance correction operation according to the luminance degradation characteristic of the display element.

A series of operations for updating the correction memory may be performed at predetermined intervals, or may be continuously performed.

It is desirable that the luminance correction operation is performed during a period other than the video output period. This eliminates the need to interrupt the video display halfway.

More specifically, the operation of capturing the luminance information of the pixel is preferably performed by causing at least the pixel to emit light during a period other than the video output period.

A period other than the video output period is a vertical blanking period, and it is desirable that luminance information be taken in for a certain number of pixels within the period. This is because the vertical blanking period has more time than the horizontal blanking period, so that luminance information can be captured for a certain number of pixels.

It is desirable not to drive adjacent pixels continuously. When adjacent pixels are driven continuously, the light emission period becomes short, but the light emission becomes linear, and the light emission may be recognized in a streak shape. Therefore, in order to solve such a problem, adjacent pixels are not continuously driven.

According to another aspect of the display panel driving method of the present invention, the correction value is calculated by using both the measured luminance information and the deterioration characteristic relating to the luminance of the element or pixel whose luminance is measured. It is characterized by.

According to the above configuration, highly accurate luminance correction can be performed.

In particular, in the case of a display panel having a light emitting surface having a phosphor, a deterioration characteristic regarding the luminance of the phosphor may be used instead of the deterioration characteristic regarding the luminance of the element or the pixel.

Further, the deterioration characteristics are measured in advance, the degree of deterioration is calculated based on the integrated driving amount for each pixel, and a correction value is calculated using both the measured luminance information and the correction memory. It may be updated. In addition, the correction operation may be continued until the difference between the measured luminance information and the luminance setting value becomes equal to or less than a certain value.

The luminance information to be captured includes a driving current,
The light emission starting point of the pixel can be used.

When the display panel has at least an anode electrode and a light emitting surface having a plurality of phosphors on the anode electrode, an anode current can be used as luminance information to be taken.

In another embodiment of the display panel driving method according to the present invention, at the initial stage of forming the display panel, for each of the pixels constituting the display panel, the pixels emit light one by one, and the luminance information of the pixels is taken in. Performing a brightness setting operation such that the brightness is set twice or more and the respective brightness set values are different, a correction value is calculated from the fetched brightness information and the brightness set value, and the correction value is stored in a correction memory. It is characterized in that it is stored as an initial correction value. The correction may be performed using the initial value as described above.

In the correction, the input luminance signal may be corrected according to the correction value stored in the correction memory, or the amplitude value or time width of the drive signal applied to the display panel may be corrected. In some cases, gamma correction is performed by calculating and storing a correction value that also has gamma correction data for each pixel in the correction memory.

In the method of driving a display panel according to the present invention, amplitude value control or time width control is performed as a method of realizing a gradation of the display panel. Then, it is desirable to change only the direction of increasing the current or voltage value of the amplitude value control except when terminating the output.

Further, as a method of realizing the gray scale of the display panel, there is a case where a driving method in which amplitude value control and time width control are performed simultaneously. Specifically, gradation control is performed for n bits (n
Is the upper m bits (m
Is an arbitrary integer), amplitude value control that outputs a current or voltage value whose amplitude is controlled at an interval of 1/2 m of the maximum value, and 1/2 of the maximum value by using lower (nm) bits.
^It is desirable to perform time width control in which the time width is controlled at ^(nm) intervals.

The current or voltage value output LSB may be output twice, or the output time width LSB may be output twice, or both may have two LSBs.

The output division number of the time width control may be larger than the output division number of the amplitude value control.

In the method of driving a display panel according to the present invention, as a method of realizing the gradation of the display panel, a gradation control method in which amplitude value control or time width control and amplitude value control and time width control are performed simultaneously. In some cases, a driving method for realizing a gray scale by switching between the above-described methods is used.

More specifically, when the level of the luminance signal to be output is smaller than a certain reference value, amplitude value control or time width control is performed. When the level is equal to or larger than the reference value, amplitude value control and time width control are performed. It is desirable to realize a gray scale by performing a gray scale control method for simultaneously performing the above.

The reference value is the number of output gradations, and there may be a case where there is provided a means for setting the number of gradation steps on the time width control side in a gradation control method for simultaneously performing amplitude value control and time width control.

Further, the gray scale may be realized by switching the gray scale realization method depending on the time.

According to another embodiment of the present invention, there is provided a luminance correcting device and a driving device for specifically realizing the above-described method for driving a display panel.

[0060]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment <Basic Driving Operation of the Present Invention> The principle of operation of the present invention is shown in FIG.

Reference numeral 9 denotes a display panel in which, for example, a large number of electron-emitting devices are arranged in rows and columns. The electrode for data input and the electrode for scanning signal input of the display panel are respectively connected to the driver. Reference numeral 8 denotes a scanning driver which sequentially scans a panel wired in a matrix line by line. For example, there are switching circuits for the number of rows inside, and only a certain selected row is
It has a function of connecting to either the DC voltage source Vy (not shown) or 0 V, and connecting to the other rows with the other voltage value. On the other hand, reference numeral 7 denotes a signal driver to which a modulation signal for controlling light emission of each element is applied. This signal driver 7
Receives a luminance signal (gradation signal) generated from a video signal, for example, and applies a voltage (or current) value according to the gradation signal to each pixel. This signal driver 7
Has a shift register and a latch circuit, and converts a luminance signal input in time series into parallel data corresponding to each pixel. A voltage (or current) value according to the gradation signal is applied to each pixel. For example, in a panel composed of electron-emitting devices, in each pixel,
Electrons corresponding to the gradation signal are emitted, and the phosphor emits light.
A pixel emits light in each selected row according to a luminance signal, and is sequentially driven by a scanning driver to form a two-dimensional image.

Next, the flow of the input video signal will be described. Although the input signal is represented by a video signal, any other signal may be used as long as the signal displays an image. The input composite video signal is converted to RG
The luminance signal of B is separated into horizontal and vertical signals. The RGB luminance signal is digitally converted by the A / D converter 3.
The controller 2 receives the horizontal and vertical signals from the video decoder 1 and generates various timing signals synchronized with the signals.

Next, the correction circuit 12 will be described. In order to suppress variation in brightness between pixels, a value related to brightness is measured by a brightness measuring unit. Reference numeral 10 denotes an anode current measuring means. This is because when the display panel is composed of electron-emitting devices, a phosphor and an anode electrode are arranged on the opposing surface of the electron-emitting device, and the emission current from each pixel may be measured by measuring the current flowing through the anode electrode. Will be. For example, if a measuring resistor is arranged in series between the anode power supply and GND (common potential), the emission current amount can be detected as a voltage value. Further, the drive current signal from the signal driver 7 is obtained by detecting a drive signal applied to the display panel. A correction value is calculated using one of these values related to luminance. Correction value calculator 6
Calculates a value related to the measured luminance and a target luminance value or a shift amount, and stores a correction value such that each pixel has the target luminance in the correction value memory 5. The corrector 4 fetches, from the correction value memory 5, a correction value synchronized with the pixel position driving the luminance signal input in time series,
Make corrections. The corrected signal is input to the signal driver.

As described above, the gradation signal is corrected in accordance with the luminance characteristics of each pixel. The luminance correction may be performed by a decoder (not shown) in the signal driver 7 using a correction value memory.

The operation of each part will be described below.

<Structure of Display Panel> The display panel 9 is composed of a plurality of elements, and will be described using, for example, the electron-emitting elements shown in FIG.

In FIG. 2, reference numeral 20 denotes a glass substrate;
The cathode electrode 25 is formed thereon. Reference numeral 24 denotes an electron-emitting device, which may be made of any material that can easily emit electrons, such as carbon-based materials, carbon nanotubes, graphite, and diamond. Further, silicon or whisker (zinc oxide whisker) may be used. Insulating layer 2
6, an extraction electrode 23 is formed. When a voltage higher than a certain value is applied between the cathode electrode 25 and the extraction electrode 23, electrons are emitted from the electron-emitting device 24. Reference numeral 21 denotes an anode electrode which accelerates the emitted electrons to collide with the phosphor 21. The phosphor emits R, G, and B light, respectively. Reference numeral 31 denotes an anode power supply, 29 denotes a cathode power supply, and 30 denotes an extraction power supply. When the electron-emitting devices are arranged in a matrix and, for example, the gate electrodes 23 are arranged in rows, the gate switch 28 functions as a scan driver, and the row electrodes are sequentially connected to the power supply 30. On the other hand, the cathode electrode 25 is in the column direction, and the cathode switch 27 is a function of the signal driver 7 and is turned ON by data such as a video signal. Turn OFF.

When the display panel 9 is constituted by organic EL elements, an equivalent circuit is as shown in FIG. An equivalent circuit of the organic EL element can be expressed as a diode 32. The organic EL elements are arranged in a matrix to form a display panel 9. Connect the C1 to C3 electrodes to the signal driver 7,
L1 to L3 are connected to the scanning driver 8 for driving.

Although not shown in the figure, an LED element represented by an organic EL equivalent circuit may be used as the display panel.

<Operation of Gradation Control Circuit> The principle of the gradation control operation of the present invention will be described with reference to the drawings.

The signal driver 7 has a function of outputting gradation information to a display panel according to a video signal. FIG.
Shows a gray scale output operation, and there are mainly two types of systems which are usually performed. FIG. 4A shows output amplitude value control, in which the pixel drive time is constant.
The amplitude value is changed according to the video information. FIG. 4B shows the output time width control, in which the amplitude value is fixed and the time width is changed in accordance with the video information. The signal driver outputs the gradation information to the display panel using the method described above.

As another gradation realizing means, there is a method applied by the present applicant (Japanese Patent Application No. 11-107935).
issue). This gray scale realization method is a method capable of displaying a high gray scale without requiring high-speed response of elements and drive circuits and high-precision amplitude control. In particular,
This is a method in which output amplitude value control and output time width control are simultaneously combined and output.

FIG. 5 shows the principle of operation. It takes eight gradation values at regular intervals in the amplitude value direction and takes eight gradation values at regular intervals also in the time direction, and a combination of these values realizes 8 × 8 64 gradations. . here,
Although there are various methods depending on the decoding method, there are various methods depending on the decoding method in the time direction and the amplitude value (current or voltage) direction. For example, the amplitude value direction may take a value proportional to the power of two, and the time direction may take a value proportional to the power of two.

The number of divisions shown is not limited to this, but may be any number. The output time need not be continuous, and may be output in a discontinuous form. further,
The control may be performed by adding another LSB unit.

Next, a specific distribution method will be described. The distribution of the voltage value and the time width can be set freely, but as an example, distribution of equal division is considered. Input data is composed of upper n bits and lower m
The gradation is expressed by dividing it into bits. For example, consider a case in which a 6-bit gray scale (64 gray scales) is expressed, and the voltage value is expressed by being distributed to 2 bits (4 gray scales) and a time width of 4 bits (16 gray scales). The decoding algorithm is as follows. First, the upper 2 bits of the input data are latched as voltage value division data [A], and the lower 4 bits are latched as time width division data [B]. Next, a voltage value corresponding to the numerical value of data [A] is output over 16 sections. In addition, an output is obtained by adding 1 to the voltage value output for a section corresponding to the numerical value of the data [B].

This will be described with reference to FIGS. For example, assume that the input data is 38/64 gradation. In binary notation, [1
[00110]. At this time, the voltage value division data [A]
= 2 [10], pulse width division data [B] = 6 [11]
0]. At this time, the output waveform outputs two times the numerical value of the data [A] over 16 sections. In addition, a value 3 obtained by adding 1 to the output is output only for the section corresponding to the numerical value 6 of the data [B].

As a result, the voltage value output has a waveform as shown in FIG. 7, and the concept is to realize the gradation by stacking the minimum unit blocks of the voltage value output.

As described above, since the voltage output blocks are stacked, the distribution and the number of divisions can be arbitrarily changed. That is, when changing the voltage into 16 and the time width into four, it is only necessary to change the number of bits of the data to be latched.
The number of divisions and distribution may be determined according to the characteristics of the light emitting element.

The output shown in FIGS. 8A and 8B may be used as a distribution method or a decoder algorithm.
FIG. 7 is similar, but changes only in the direction of increasing amplitude.

When the element to be driven has an equivalent capacitor component, a certain voltage is charged in the equivalent capacitor according to the drive amplitude. Since a simple drive circuit does not include a circuit for reducing the current, the voltage of the charged equivalent capacitor cannot be reduced even if the drive for reducing the amplitude is performed. For this purpose, a method of changing the amplitude is devised. That is, since the voltage of the equivalent capacitor can be changed in the charging direction, the driving is performed to change only the current command value in the increasing direction as shown in FIG.

As described above, by changing the current command value only in the increasing direction in accordance with the characteristics of the panel to be connected, it is possible to output gradation with high accuracy.

The distribution method and the algorithm of the decoder are not limited to these, and numerical values such as the number of distributions and the number of gradations are not limited to these. The output is not limited to the voltage value, and a current output or a constant current circuit may be added according to the panel to be driven.

As described above, by simultaneously outputting the amplitude value control and the time width control, a high-speed display of the element and the driving circuit and a high gray scale display without the need for high-precision amplitude control are possible. It can be. In particular, in the case of a display device using an electron-emitting device, the response speed is higher than that of a liquid crystal or the like. However, as the resolution increases, the gradation cannot be realized by ordinary PWM. This can be a very effective means for high resolution panels.

Next, an example of the configuration of the display driver will be described with reference to the drawings.

In FIG. 9, reference numeral 40 denotes a shift register (S.
R. ) To determine the timing of sampling the data signal from the clock and the start signal from the controller.

Reference numeral 41 denotes a latch, which connects a plurality of signal data lines representing gradations to S.D. R. And latches temporary data according to the output timing.

The latched data is used by the decoder 42 to
The output value is changed according to the gradation method.

In the case of output time width control, the decoder 42
The output timing of the time width is determined based on the data stored in the latch 41. In the case of output amplitude value control, if the data stored in the latch 41 is not corrected, D
/ A.

In the case of the gradation control method in which the amplitude value control and the time width control are simultaneously combined and output, the decoder 42 decodes the data into two data in the time direction and the voltage output direction.
Hereinafter, this control method will be specifically described. The output voltage value is changed according to the progress of the time axis within the effective scanning period. Therefore, the output data from the decoder, that is, the voltage command value, is one system and is input to the D / A converter 43. The D / A converted voltage command value is input to the buffer circuit. This buffer circuit may be a general amplifier. For example, when driving an electron-emitting device, it boosts a signal voltage to a drive voltage.

Here, the decoder 42 controls the FPGA (Fiel) so that the current value and the time width can be distributed flexibly.
d Programmable Gate Array), CPLD (Complex Pro
grammable Logic Device) may be used. This kind of I
C implements a function by executing a program on software and downloading it to an IC. That is,
The distribution of the voltage value and the time width can be programmed according to the characteristics of the panel to be connected, and the gray scale can be output with high accuracy.

Since the decoder can be programmed according to the characteristics of the panel to be connected, the distribution of the amplitude (voltage and current) and the time width and the number of divisions can be changed arbitrarily.
It is possible to output the gradation with high accuracy. After the characteristics of the panel are determined, the distribution and the number of divisions are determined. Therefore, an integrated IC including a decoder may be created.

In the above-described gradation method, amplitude value control, time width control, and gradation control method in which the amplitude value control and the time width control are simultaneously combined and output, in addition to these gradation methods, Instead, a control method such as an error diffusion control or a dither method may be used as a method for further increasing the gradation.

<Structure and Operation of Luminance Capture Unit> (Configuration 1 of Luminance Capture Unit) A CCD is generally used as a device for capturing luminance. When luminance is taken in for initial correction at the stage of shipping the image evaluation device, a CCD may be used. Hereinafter, a case where the luminance capturing means is a CCD will be described with reference to FIG. The display panel 9 has pixels composed of R, G, and B sub-pixels. For example, if the resolution is VGA, there are 640 horizontal pixels, 640 × 3 subpixels, and 480 vertical pixels. CCD from the display panel 9
Measure at 50. The resolution of the display panel 9 and the CCD 50
Have the same resolution, and if the alignment is accurate,
The information captured by the CCD as it is becomes the luminance information from the RGB sub-pixels. When the luminance information of the RGB sub-pixels is sent to the correction calculator 6, a correction value for each sub-pixel is calculated and stored in the correction value table 5.

When alignment is difficult or when the CCD 5
For example, when the resolution of 0 is lower than the resolution of the display panel 9, the RGB sub-pixels of the display panel 9 may be sequentially turned on, and the luminance information of the sub-pixels may be sequentially measured.

In order to improve the S / N (signal, noise) ratio when the resolution of the CCD is low, and to improve the S / N (signal, noise) ratio, FIG.
The measurement may be performed using three CCDs. It comprises a dichroic prism 51 and three CCDs 52, 53, 54. With the dichroic prism 51,
The input light is color-separated, respectively, and is incident on three CCDs as R, G, and B light. The resolution of each CCD may be the same as the resolution of the display panel 9, and the luminance of each sub-pixel can be collectively measured with a good S / N ratio.

In the above CCD capturing means, the resolution of the display panel 9 is HD class (1980 × 1080).
, It becomes difficult to collectively capture data using a CCD. At this time, each small area obtained by dividing the display panel 9 is captured by a CCD and the luminance is measured. For example, the display panel 9 is divided into four, and the luminance is individually measured in each small area. In addition, when data of a small area is combined as one screen, a luminance shift may occur at a joint of the small areas due to in-plane uniformity of the CCD. In this case, it is preferable to measure the characteristics of the CCD in advance and apply the correction.

(Configuration 2 of Luminance Acquisition Means) In the case of luminance correction for a change over time, it is necessary to perform the luminance acquisition operation again after a certain period. When the CDD is used, it is necessary to install the CCD again, and the convenience is impaired. Therefore, instead of the CDD, a unit that enables the display device itself to measure the luminance without adding an external measuring unit when measuring the luminance again after a certain time is used instead of the CDD.

FIG. 2 shows a luminance capturing means. This is one in which the display panel 9 is composed of electron-emitting devices (FIG. 2), and is a part of the anode electrode 21 and the anode power supply 31. A resistance for measurement is inserted in series between GND (common potential) and an anode power supply 31. Electrons emitted from the electron-emitting device are accelerated by the anode electrode 21 and collide with the phosphor to emit light. The emission current corresponding to the luminance at this time flows from the anode electrode 21 to the anode power supply 31. This current is detected by the measuring resistor 55. For example, when the emission current is 2 μA, the resistance value of the measuring resistor 55 is 2 μA.
If it is 50 kΩ, it corresponds to 5V. The measured value is converted into a digital signal through, for example, an A / D converter 58 and input to the correction value calculator 6 as luminance information.

(Configuration 3 of Luminance Capture Means) FIG. 13 shows another luminance capture means. This is because the current limiting resistor 56 is connected in series between the display panel 9 and the signal driver 7. This current limiting resistor 56
When the display panel 9 is composed of electron-emitting devices,
Generally, a DC resistance is inserted in order to suppress a current fluctuation of the electron-emitting device.

The current flowing through the current limiting resistor 56 is
It corresponds to the amount of electrons emitted from the electron-emitting device 24 after flowing to the anode electrode 25, and may be considered equivalent to the emission current. For this reason, the drive current from the signal driver 7 is detected by the current limiting resistor 56 and is input to the correction value calculator 6 as luminance information via an A / D converter (not shown).

(Structure 4 of Luminance Capture Unit) As another luminance capture unit, a current detector using the Hall effect is used instead of reading a current value as a voltage value using a resistor as described above. Is also good. In this case, since the current value can be detected in a non-contact manner, a control circuit separated from the high-voltage drive system can be formed.

<Operation of Luminance Acquisition Unit> A method of actually extracting a luminance signal in the luminance acquisition unit described above will be described. Pulse driving is performed during a short pause period of an image, and information related to luminance (for example, anode current) is captured. FIG. 14 shows an example of the detected waveform at this time.
(A). Since the driving has a pulse waveform, the detection amount also has a pulse waveform. The luminance information corresponds in principle to the integrated value of the detected waveform. If a high-speed integration circuit can be constructed, it is ideal to use the amount of integration of the detected waveform as luminance information.

Actually, however, the pulse driving time is short, so that the conversion speed of the integrating circuit becomes severe. Therefore, a method that can take in a value with a simple configuration without using an integral value will be described.

FIG. 14B shows an example in which the final value of the amplitude value in the detected pulse waveform is used as the amount of capture. this is,
From the viewpoint of the response speed, it is suitable when it is desired to take as long a time as possible. It consists of a sample and hold circuit, etc.
The drive signal can be used as it is as a capture signal.

FIG. 14C shows an example in which the peak value of the detected pulse waveform is fetched, and can be constituted by a peak hold circuit.

FIGS. 14 (d), (e) and (f) are effective means as noise countermeasures.

FIG. 14D is a diagram showing an example in which noise is present on the detected pulse waveform, and accurate information cannot be detected as it is. Therefore, the capturing means (a) to (c) are applied again by using a pulse waveform after passing through a low-pass filter that cuts high-frequency components.

FIG. 14E is applicable to a case where luminance information varies to some extent due to the characteristics of the driving element. Also, the present invention can be applied to the case where the noise varies due to noise. Although any of the capture points (a) to (c) may be used as the capture point, the luminance capture operation is performed a plurality of times, and the average value thereof is calculated to obtain luminance information. By performing this operation, the singular points of the captured values can be averaged.

FIG. 14F shows a case where the commercial frequency (60 Hz in western Japan) is included as noise. At this time, the waveform is obtained by adding the component of the commercial frequency to the detection pulse waveform. On the other hand, if a filter that passes only high-frequency components is used, only the detected pulse waveform can be captured. Further, when the luminance capturing operation is synchronized with the commercial frequency, it is possible to always detect the luminance at the same phase as the commercial frequency, and to remove the component.

As described above, it is possible to remove the noise component by using the methods shown in FIGS.

Further, by adopting the above-described method, luminance information can be acquired with a simple configuration.

<Operation of Brightness Correction> FIG.
2 is a functional block diagram. The correction circuit 12 has a function of suppressing variation in luminance between pixels. First, a value related to luminance is measured by the luminance capturing means 57 described above. A value related to the luminance is input to the correction value calculator 6 to calculate a correction value. The correction value calculator 6 performs a comparison operation between a value related to the measured luminance and a target luminance value or a shift amount, and stores a correction value such that each pixel has the same luminance in the correction value memory 5. . The corrector 4 takes out a correction value synchronized with the pixel position to be driven from the correction value memory 5, and corrects a video signal (luminance signal) input in a time series. The corrected signal is input to the signal driver. As a correction method, a method in which a signal driver fetches a correction value synchronized with a pixel position to be driven from the correction value memory 5 and changes a gradation command value may be used. As described above, the correction value corrects the gradation signal according to the luminance characteristics of each pixel.

(Brightness Correction Method 1) A correction method will be described. FIG. 16 shows the voltage-current characteristics of the electron-emitting device as an example. The characteristics are non-linear. When the gradation control is realized by changing the current value at a certain interval, the drive voltage does not become a step of the same interval. Therefore, if the value of the video signal is input as it is, a shift occurs. Further, the current characteristics are not the same for all the electron-emitting devices in the display panel, but are different from each other. In order to make the characteristic proportional to the input signal, the relationship shown in FIG. 16B must be corrected. In order to perform this correction, first, the luminance capturing means 57. The luminance information of all pixels is taken in and compared with the target luminance. If the luminance is different from the target luminance, the driving voltage is changed and the luminance is measured again. By repeating this, a voltage value converging to the target luminance is determined. In addition, when the element characteristics are measured in advance, a drive voltage having a target value may be used. The value that becomes the target luminance is written in the correction value table. This correction value may be an absolute value or a proportional coefficient to a certain reference value. For example, since the target luminance has four steps in FIG. 16, a correction value is obtained for each step and written to the correction value table. For this reason, the correction value table prepares the number of pixels (pixels or sub-pixels) × the number of gradation steps.

In the case of gradation control based on ordinary pulse width modulation, there is only one target current value, and the correction table may be equivalent to the number of pixels. The corrector 4 takes out the correction values from the correction value table and performs the correction sequentially by synchronizing the sequentially input video signal with the display location. At this time, the value of the correction value (voltage or current value) may be used as it is,
A correction formula may be obtained from the correction value, and the input signal may be corrected using a calculation formula.

As described above, the present invention is a driving method for performing gamma correction of a video input signal using this luminance table. By preparing data for each gradation for all pixels and performing correction, it is possible to accurately correct luminance variations in the display panel.

(Luminance Correction Method 2) Another correction method will be described. FIG. 17 shows driving characteristics of pixels at a certain place of the image display device. As an example, the voltage-current characteristics of the electron-emitting device are shown, and the characteristics are non-linear.

First, the signal driver 7 performs, for example, output time width control. Then, it is assumed that only a specific pixel is driven, for example, by an all-white signal (at the driving voltage V0). At this time, the luminance of the pixel becomes IO. The electron-emitting devices that constitute pixels have variations in characteristics, and the same luminance is not always obtained even when driven by the same voltage. In the characteristic shown in FIG. 17, when a certain target luminance value is Id, the luminance is insufficient because the actual luminance is IO.

The luminance information is measured as the emission current value Ie by the anode current taking means. It is assumed that the emission current value and the actual luminance are measured in advance and have a correlation. The emission current value Ie is compared with a target value (a value correlated with the target luminance value Id). In this case I
Since the value of e is smaller, the correction value is changed in a direction to increase the drive voltage. When the driving method is the output time width control, the amplitude value (driving voltage) is corrected. At this time, the correction value may be the value of the drive voltage itself or a proportional coefficient.

The luminance taking-in and the correction operation are sequentially performed for all the pixels. When the correction value has been changed once for all the pixels, the correction operation is performed again.
That is, the change of the correction value is repeated until the deviation between the luminance information (the emission current amount Ie and the target value (a value correlated with the target luminance value Id)) becomes equal to or smaller than a certain value. The target of the deviation is desirably 40 dB or less of the target value, depending on the image to be displayed, and the gradation realization waveform of the pixel is shown in Fig. 18. Before the correction, the amplitude value was VO. It can be seen that the amplitude value is Vd after completion (the convergence condition will be described later).

As described above, by correcting the drive voltage according to the characteristics of each pixel, all the pixels can be adjusted to the target luminance, and the luminance variation can be improved.

Further, in the case of gradation control by ordinary time width modulation, one target amplitude value is sufficient, and the correction memory may be prepared for the number of pixels.

Note that the present invention is not limited to the time width control, but may be amplitude value control. In this case, the correction value may be a time width or an amplitude value.

(Luminance Correction Method 3) Next, a correction method using another gradation method will be described. At this time, instead of using the corrector 4, a decoder in the signal driver performs correction using the correction value in the correction value memory 5. The decoder employs a method of realizing gradation control by simultaneously performing amplitude value control and time width control. FIG. 20 is an example, and realizes a total of 16 gradations including 4 gradations in time width and 4 gradations in luminance value (emission current value).

The operation for correcting the luminance variation will be described. FIG. 19 shows two characteristics. This is a characteristic of the adjacent pixels A and B at a certain position of the display panel 7. Driving is performed with a driving voltage V0 for a certain target luminance value I0. At this time, it is assumed that the pixel A emits light at the luminance IA and the pixel B emits light at the luminance IB. At this time, the drive voltage is corrected so that both emit light with the same luminance. The correction value is set so that the driving voltage of the pixel A becomes VA and the driving voltage of the pixel B becomes VB. At this time, the value of the correction value (voltage or current value) may be used as it is as the set value, but the input signal may be corrected using a calculation formula by obtaining a correction formula from the correction value. Also. A coefficient value (gain) from the reference value may be used as the set value.

By correcting the drive voltage in accordance with the characteristics of each pixel, the luminance can be made the same. The output waveforms of the pixels A and B are as shown in FIG. This is because the drive voltage value of the pixel B is higher than that of the pixel A, but is corrected so as to have the same luminance.

At this time, it is necessary to find a drive voltage that changes the luminance in four steps at equal intervals. For each element (pixel or sub-pixel unit), a correction value or a drive voltage value such that the luminance value becomes four steps at regular intervals is
It is necessary to write to the correction value memory. The correction value memory is prepared by the number of pixels (pixels or subpixels) × the number of gradation steps. The decoder in the signal driver 7 takes out the correction value from the correction value memory in synchronization with the pixel to be driven, corrects the drive voltage, and outputs a drive waveform as shown in FIG.

As described above, by using the correction value memory by the decoder and correcting the drive voltage in each pixel so that the luminance step becomes the target value, the luminance can be accurately controlled. This makes it possible to accurately correct variations in luminance in the display panel.

As described above, the provision of the brightness fetching means and the correction value memory makes it possible to correct the uneven brightness of the pixels.

Note that the number of gradation steps is not limited to this, and may be any number. Although the drive voltage value is corrected, the invention is not limited to this, and the drive current value may be corrected.

At this time, constant current control for keeping the drive current constant may be performed. In this method, the drive current constant control is normally performed so that the cathode current is constant, and the luminance can be controlled accordingly. For this reason, it is considered that no correction is necessary. However, in practice, even if the anode current is controlled to be constant, the luminance does not become constant due to leakage current to the extraction electrode and the like. In other words, the present invention in which the luminance is accurately controlled by correcting the current value in accordance with the luminance even in the driving method in which the constant current control is performed is effective.

The gradation control method is not limited to this, and the time width may be used as the correction value.

(Luminance Correction Operation 4) By combining output time width control and output amplitude value control with the above configuration, high gradation can be realized without requiring high speed and high precision in the elements and the drive circuit. This is a gradation realization method. However, in this gradation control method, at the time of low luminance, a problem as described with reference to FIG. 51 has occurred.

Therefore, when displaying low luminance (for example, when outputting the first 16 gradations), it is necessary to increase the amplitude value (drive voltage or current) in order to increase the response speed. (FIG. 21).

That is, up to the first 16 gradations, the amplitude value is doubled and the gradation is output only by the amplitude value control (FIG. 2).
2). At this time, the time width is reduced to ２, but since the time width is twice as long as the normal time width control (when the amplitude is set to ／), the response speed is in a range that follows.

As described above, by doubling the amplitude width and outputting the gray scale only by the time width control, the response speed of the element follows, and the output can be performed accurately even at the low gray scale. When the first 16 gradations have passed, the time width control ends, and the system returns to the normal gradation realization method (FIG. 22B).
This means that the gradation values after the 17/63 gradation have an amplitude value of 2 /
This is because the response speed is 4 or more, and there is no problem in response speed.

As described above, the gradation method in which the time width control is performed on the low luminance side and the time width control and the amplitude value control are simultaneously performed on the high luminance side, and by switching between the two methods, the gradation on the low luminance side is obtained. The key can be output with high accuracy.

When the response speed becomes slow on the low luminance side, amplitude width control may be used as shown in FIG. 23A instead of time width control. This extends the time width to 1/2 of the maximum value, and extends the time for which the response of the element follows. By performing such control, even if amplitude value control is performed, gradation can be output with high accuracy. For this reason, on the low luminance side (for example, when outputting the first 16 gradations)
In FIG. 23, the amplitude value control is performed. When the amplitude value is exceeded, the amplitude value control ends, and the process returns to the normal gradation realization method (FIG. 23).
(B)). Thus, the amplitude value control is performed on the low luminance side,
By performing a gradation method for simultaneously performing the time width control and the amplitude value control on the high luminance side and switching between both methods, it is also possible to accurately output the gradation on the low luminance side.

In the above two realization methods, the first 16 gradations, that is, the number of gradations of the time width control in the gradation method for simultaneously performing the time width control and the amplitude value control are used as the switching timing. It is not limited to this.

For example, the gradation method may be switched with 50% of the number of gradations as a boundary. When the luminance or the number of gradations is 50% or less of the maximum value, the amplitude value control or the time width control is performed. When the luminance or the number of gradations is 50% or more of the maximum value, the time width control and the amplitude value control are simultaneously performed. A gradation method may be performed. This threshold value of 50% is obtained when the brightness is low.
For example, when the output time width control is performed with the amplitude value being fixed at 50% of the maximum value, the achievable luminance is 50% of the maximum value.

(Luminance Correction Operation 5) In addition to the control method of the present invention described in the above (Luminance Correction Operation 4), a method of switching the gradation realization method according to time will be described.

FIG. 24 shows an example, which will be described with reference to the drawings. In FIG. 24, a case is considered where, for example, the gradation realization method 1 is performed up to 16 gradations on the low luminance side, and thereafter the gradation realization method 2 is performed for 17 or more gradations.

The gray scale realization method includes an output time width control, an output amplitude value control, a gray scale method for simultaneously performing the output time width control and the output amplitude value control, and the like, and may be arbitrarily selected according to the element. .

At this time, since the two gray scale realization methods are different, a luminance shift may occur at the boundary. For this reason, when an image is displayed, a difference in luminance occurs in that portion, and a problem occurs that the image is seen as a pseudo contour.

In order to alleviate this problem, FIG.
As shown in FIG. 5, the number of gradations for switching the gradation realization method is changed with time. In FIG. 25, in the first frame, the gradation realization method 1 is performed up to the 16th gradation, and the gradation realization method 2 is performed from the 17th gradation. The next frame is 17
The gradation realization method 1 is performed up to the gradation, and the gradation realization method 2 is performed from the 18th gradation. This is repeated for each frame.

As described above, by changing the number of gradations to be switched for each frame and reducing the change in luminance,
This is to make it impossible to recognize a luminance shift.

As described above, the gray scale can be displayed without a sense of incongruity by switching the gray scale realization method according to time.

Note that the method of switching according to time and the amount of switching (one gradation) are not limited to this, and may be two gradations or more. The switching timing (one frame) is not limited to this, and may be two or more frames or a different time unit. It suffices that the luminance shift be less noticeable in accordance with the characteristics of the element to be displayed.

<Operation of Time-Dependent Change Correction>
The brightness correction method is a method of correcting uneven brightness in an initial state. This is because uniform display can be performed by correcting the initial characteristics in inspection at the time of panel shipment. But,
Even if there is no luminance unevenness in the initial state, for example, when the same information is displayed for a long time, the pixel that is displaying may deteriorate more than other pixels. For example, even if the same drive voltage is applied, the luminance of the deteriorated pixel decreases. For this reason, when all the pixels are made to emit light at 100% luminance next, even if the correction is performed using the correction table,
The luminance of the light-emitting element in a part where certain information is displayed is lower than that of the other part because the light-emitting element is deteriorated. Therefore, a luminance difference occurs, and a phenomenon such as burn-in visually occurs.

In order to solve this phenomenon, the correction value memory is changed again by using the above-described luminance correction method.

For example, with respect to a display panel after a certain period of time (eg, 1000 or 2000 hours),
Perform the correction again. However, since the correction operation is sequentially performed for each pixel, a certain period of time is required, and a problem occurs that the video display must be interrupted during the operation.

The present invention makes it possible to correct luminance variations without interrupting video display. An operation example will be described below.

FIGS. 26 and 27 schematically show video information and a scanning method used in a CRT or the like. In CRT, to scan the electron beam,
There is always a blanking period (blanking period). Also,
The current terrestrial broadcast NTSC video signal also has this retrace period, and has a horizontal blanking period (FIG. 26) and a vertical blanking period (FIG. 27).

According to the NTSC standard (EIA RS-170A), the horizontal blanking period is 10.9 ± 0.2 μs, and the vertical blanking period is 20H (H: 1 horizontal scanning period, about 6
(3.5 μs) = 1.27 ms. Also,
According to the HDTV standard, the horizontal blanking period is 3.
77 μs, and the vertical blanking period is determined as 45 lines (line frequency 33.75 kHz) = 1.33 ms.

During this flyback period, there is no video output and there is no free time. The luminance correction operation for a certain pixel is performed using the blanking period.

In the operation of correcting the luminance variation in the initial stage, the influence on the video output need not be considered, so that the luminance correcting operation may be performed continuously. In the initial correction, this correction operation may be performed during a blanking period.

<Apparatus Configuration> When the above-described gradation driving method and luminance correction method are realized, they are generally realized as a driver IC. At this time, the circuit for calculating the correction value, the correction table, the corrector, and the like may be integrated into one chip. Further, a configuration is also conceivable in which a correction table is provided in a driver IC that realizes gradation and correction is performed. In this way, by integrating the functional blocks into one chip, the driver cost can be reduced and the cost can be reduced, and the entire device can be reduced in size and weight.

Further, also in an image display device equipped with this driving device, it is possible to provide a small, lightweight and inexpensive device which realizes gradation with high accuracy, suppresses luminance variations, and provides a low-cost device.

According to the embodiment of the present invention described above, by adopting a gradation realizing method in which the time width control and the amplitude value control are performed at the same time, the gradation can be accurately controlled even for a high-resolution display panel. The output can be output, and furthermore, by configuring the luminance correction means using the correction memory, it is possible to suppress the luminance variation even at the initial stage and with time. This makes it possible to improve the performance and characteristics of a panel that has conventionally been defective in gradation and uniformity during panel manufacturing. Therefore, the manufacturing yield can be improved, and an inexpensive and high-quality image display device can be provided.

In the above embodiment, the gradation control and the luminance correction have been described by taking the electron-emitting device as an example. However, the present invention is not limited to this, and the present invention is not limited thereto. Driving is also applicable.

(Embodiment 2) As Embodiment 2, another example of the operation of the time-dependent change correction will be described. A luminance correction method according to the second embodiment will be described with reference to FIG. Consider a blanking period (horizontal or vertical). This series of operations is performed during this blanking period, in which pixels are driven to emit light, luminance information is taken in (for example, an anode current), a correction value for driving is calculated, and the calculated value is stored in a correction memory. If this operation is performed during the blanking period, the luminance correction operation can be performed without affecting the video output.
In addition, since the pixels that emit light are one pixel at a time, which is extremely short, there is an advantage that the user does not recognize the pixels.

For example, it is assumed that this operation is performed during the horizontal blanking period of NTSC. Assuming that the element is capable of high-speed response and can emit light during this period (10.9 μs), a correction operation can be performed pixel by pixel during one horizontal blanking period. Since the correction can be performed without affecting the video output, the correction time does not need to be considered,
For example, in the case of a panel whose resolution is equivalent to VGA, one measurement time is 640 × 480 × 1/525 × 1/30 = 1.
It becomes 9.5 (sec).

In an element having no response speed on the order of μs, the correction operation may be performed during the vertical blanking period. For example, the vertical blanking period of NTSC
Since the time is 1.27 ms, a sufficient correcting operation can be performed. Only one pixel may be measured during the vertical blanking period.
If completed in 0 μs, a plurality of pixels can be corrected during this blanking period.

At this time, a luminance correction operation of 10 pixels can be performed in one vertical blanking period. Again,
Since the correction can be performed without affecting the video output, the correction time does not need to be considered. For example, in the case of a panel having a resolution equivalent to VGA, one measurement time is 640 × 480 × 1/100 × 1/60. = 51.2 (se
c).

As described above, during the blanking period of the video signal, the pixel is driven to emit light, luminance information is taken in, the correction value for driving is calculated, and the operation is stored in the correction memory. By performing this series of operations during this blanking period, a luminance correction operation can be performed without affecting the image output.

(Embodiment 3) As Embodiment 3, another example of the operation of the temporal change correction will be described. FIG. 29 shows a luminance correction method according to the third embodiment. Consider a blanking period (horizontal or vertical). During this blanking period, only the operation of driving the pixels to emit light and taking in luminance information (for example, anode current) is performed. In this case, only a minimum operation is performed during the blanking period, for example, when the resolution is increased and the blanking period is shortened. As long as luminance information is taken in during the blanking period, the subsequent correction calculation and memory saving operation can be performed simultaneously and in parallel, even if they overlap with the image output operation.

A luminance information temporary storage memory (not shown)
For example, only the pixel light emission and the luminance information capturing operation are performed in advance for all the pixels, and are temporarily stored in the luminance information temporary storage memory. Thereafter, regardless of the video output timing, the operation of reading the luminance information from the luminance information temporary storage memory and performing the correction value calculation and the memory correction for all the pixels may be performed.

As described above, even if only the operation of illuminating the pixel and taking in the luminance information is performed during the blanking period, and the operation of calculating the correction value and storing it in the correction memory is performed at other timings, the image output is not affected. The brightness correction operation can be performed.

(Fourth Embodiment) As a fourth embodiment, another example of the operation of the time-dependent change correction will be described. FIG. 30 shows a flowchart of a correction procedure for the entire display panel. First, in a certain pixel, the pixel emits light in step 10. Next, at step 11, luminance information is fetched. In the case of a display panel including an electron-emitting device, a drive current or an anode current may be detected. In step 12, a correction value is calculated, and in step 13, it is stored in a correction memory. Steps 10 to 13 so far may proceed in the same manner as the luminance correction operation described above. That is, steps 10 to 13 may be performed in one blanking period, or only steps 10 and 11 may be performed in one blanking period. Next, regarding the convergence determination, the acquired luminance information is data corresponding to the luminance value, and can be compared with a certain reference value (target value). Although this value differs depending on the gain of the luminance acquisition system, it can be considered that there is some relationship (for example, a proportional relationship or a power relationship) with the luminance value. Therefore, a relationship between a required luminance value and luminance information (for example, an anode current value) is measured in advance, and a desired target value can be set. In step 14, the difference between the acquired luminance information and a certain target value is calculated, and it is determined whether or not the difference has become smaller than a certain value. The criterion is closely related to the allowable range of the luminance variation between adjacent pixels. For example, if the deviation is 40 dB or less with respect to the target value, the deviation is about 1% or less. If the deviation is equal to or larger than the numerical value, the same pixel is driven again with the changed correction value. That is, the process returns to step 10. In this manner, by repeating the correction operation, the deviation converges to a certain value or less at a certain number of times. If the deviation converges at a certain pixel, the process proceeds to step 15 and proceeds to the next pixel. Then, in step 15, it is determined whether all pixels have been completed. If all pixels have not been completed, the process returns to step 10 and the same operation is repeated. If all the pixels are completed, the correction operation is completed. For each pixel of all the pixels, the deviation is less than a certain value, and as a result, the luminance variation converges to a certain value or less.

Note that the luminance capturing operation for each pixel may be performed continuously during each video blanking period, or may be performed at an arbitrary timing instead of continuous.

By performing such a correction procedure, it is possible to correct the luminance in all the pixels of the display panel, and it is possible to suppress the luminance variation.

(Fifth Embodiment) As a fifth embodiment, another example of the operation of correcting the change with time will be described. FIG. 31 shows a flowchart of a correction procedure for the entire display panel. In this flowchart, the correction is performed once over the entire screen. In the above-described embodiment, the luminance correction is performed on the same pixel until the deviation converges. However, in this method, depending on the convergence situation, only the same pixel shines, and light emission may be recognized. For this reason, in this embodiment, the luminance correction is performed only once for the pixels that constitute one screen. Until all pixels converge
This operation is repeated.

Steps 21 to 23 are the same as the operations described above. Next, the process proceeds to the next pixel without performing the determination operation. Then, the operations of steps 20 to 24 are repeated until the operation is completed for all the pixels. Once the correction operation is completed for all pixels, the convergence state is examined. This involves examining the deviation between the acquired luminance information and a certain target value, but this is determined at the measurement stage at each pixel, and a determination table (not shown) prepared for each pixel is prepared. good.
For example, in step 27, the convergence state of each pixel is checked using this determination table, and if the deviations of all the pixels have not converged, the correction operation is started again. In this case, the process returns to step 30. At this time, regardless of the convergence status of each pixel,
The correction work may be performed again for all the pixels, or only the pixels that have not converged according to the determination table may be corrected again. In step 27, if the deviations of all the pixels converge to a certain value or less, the correction operation ends.

Note that the luminance taking-in operation for each pixel may be performed continuously during each video blanking period, or may be performed at an arbitrary timing instead of continuous.

By performing such a correction procedure, it is possible to correct the luminance in all the pixels of the display panel, and it is possible to suppress the luminance variation.

(Embodiment 6) As Embodiment 6, another example of the operation of the time-dependent change correction will be described. In the above-described operation of the temporal change correction, an operation is performed in which a certain pixel emits light and its luminance information is captured. This is because, as shown in FIG. 32, the luminance characteristics of a certain pixel change with the passage of time. It is assumed that when the initial characteristic is the curve of A, the characteristic of B is obtained after a certain time has elapsed. At this time, the threshold voltage and the degree of inclination of the characteristics have also changed, and the correction cannot be performed unless the luminance is measured again. The characteristics of ordinary elements change as described above, but some elements change as shown in FIG. In FIG. 33, the initial characteristic is a curve of A, and the threshold voltage (voltage at which light emission starts) is Vth (A). This element changes to the characteristic B when a certain time has elapsed. At this time, the characteristic B is a characteristic obtained by only translating the characteristic A, and the slope of the curve does not change, only the threshold voltage changes to Vth (B). In such an element that changes over time, only the threshold voltage needs to be detected when performing the luminance correction operation. In this case, in the embodiment described so far, instead of performing the operation of causing the pixel to emit light at a certain luminance and capturing the luminance information, the operation of driving the pixel and detecting the voltage value at which light emission starts is performed. The other operations may be the same. That is, the drive voltage is increased from a state in which light emission is not performed, and a current when light emission starts is detected. The current at this time may be a drive current or an anode current. If the threshold voltage can be detected,
When the correction value is a voltage value, it is only necessary to add a change in the threshold voltage to the correction value. In this case, the correction operation is performed once for each pixel, and the repeated operation is not required. At this time, in the detection of the threshold voltage, since the pixel emits very little light, the correction operation can be performed without any recognition by the user.

As described above, in the case where the characteristics of the element are only shifted in parallel due to the change over time, only the detection of the threshold voltage is required.

(Embodiment 7) As Embodiment 7, another example of the operation of the temporal change correction will be described. In the correction procedure described above, a correction value is obtained by performing a comparison operation with a certain reference value (target value) related to the target luminance from the luminance information captured for each pixel. At this time, the reference value is a drive control parameter (e.g., a drive current value, a drive voltage value, a drive time width, and the like) converted from the brightness target value in which a target brightness is set in advance.

Normally, the target value is kept constant with the passage of time, and even during a correction operation for a change with time, the luminance of a pixel determined to be lower than this target value is determined. A correction value for improving the value will be taken. That is, it is a method of correcting the luminance of all the pixels in a direction so as to become a certain target value.

On the other hand, considering the deterioration characteristics of the element, if control is performed to improve the luminance of the pixel whose luminance has decreased due to deterioration, the life of the specific element becomes extremely short. In some cases. In such a case, the target value may be set by calculating from the measured luminance information of all pixels without setting the target value to a constant value.

For example, in the luminance information measured for all pixels, the minimum value may be set as the target value. At this time, the correction in the other pixels is controlled in a direction to lower the luminance.

The target value may be not only the minimum value in the luminance information measured for all pixels but also a maximum value or an intermediate value such as an average value, a median value, or a mode value. , May be set arbitrarily according to the characteristics of the panel.

Further, in an image such as a CRT, the luminance of the entire screen gradually decreases over time due to deterioration of the phosphor. However, in human vision, since the luminance is the entire screen and the temporal luminance change is slight, the change is often not noticed. By utilizing this, it is possible to take a value that gradually decreases with time, instead of setting the target value of luminance to a constant value. That is, the target value can be a value that decreases with time as a function of time.

For example, as a curve of luminance degradation, FIG.
4 (a), (b) and (c) are possible. FIG. 34 (a) shows a characteristic in which the luminance deteriorates with time, but the element characteristic has a greater degree of deterioration than the initial stage as time passes. FIG.
(B) also shows a device characteristic in which the luminance deteriorates with time, but the degree of deterioration decreases with time as compared with the initial stage. These characteristics are deterioration characteristics that are common to ordinary elements.

On the other hand, the characteristic shown in FIG. 34C is a curve in which the luminance is held until a predetermined time, and thereafter, the luminance sharply drops. In FIG. 34C, the driving time is 2
Until 0000H, the luminance has only decreased to 80% of the initial luminance, but thereafter, the luminance sharply drops. this,
Numerical values of 400 candela, 20000H, and 80% are merely examples, and are not limited thereto, and may be set arbitrarily. With such a luminance change curve, a bright image can be maintained until a predetermined time, and quality can be guaranteed for a certain period. After that, the user is notified that the life is expired. It can be a convenient video display device for the user.

As a specific configuration, for example, FIG.
As shown in FIG. 5, the correction circuit 12 may be provided with a brightness setting device 100 as means for resetting the brightness.

By setting such a target value that gradually decreases with time, it is possible to prevent excessive driving of each element, and it is possible to extend the life of the element and the life of the phosphor.

In the present embodiment, the target value has a gradual decreasing tendency. However, the present invention is not limited to this. The target value may be any characteristic that decreases without exceeding the initial value. Further, it may be changed over time according to the characteristics of the element.

(Eighth Embodiment) As an eighth embodiment, another example of the operation of the temporal change correction will be described. In the correction procedure described above, a correction value is obtained from luminance information taken in for each pixel. At this time, the luminance information is a value obtained by detecting the anode current or the current of the current limiting resistor. this is,
It detects the amount of electrons emitted from the electron-emitting device.

Normally, when this electron emission amount is constant,
The luminance when the phosphor emits light is constant. However,
In fact, the phosphor has also deteriorated with time (see FIG. 3).
6). At this time, the emission luminance changes (decreases) despite the same amount of electrons colliding with the phosphor.

FIG. 37 shows a correction operation procedure in consideration of the deterioration of the phosphor. Steps 1 to 4 are the correction procedures described above. The difference is that in step 3, a value relating to the luminance degradation of the phosphor is calculated, and in step 3 for calculating the correction value, both the value of the acquired luminance information and the value relating to the luminance degradation of the phosphor are used. The point is that the correction value is calculated. The processing in step 5 may be performed by, for example, the phosphor luminance deterioration calculator 190 shown in FIG.

Next, the process of step 5 will be described. First, values related to the luminance degradation of the phosphor will be described. The deterioration of the phosphor with time can be estimated based on the acceleration voltage value to the phosphor, the time integral of the collision current amount, and the like. For example, when the acceleration voltage is constant,
The luminance degradation characteristic of the phosphor can be set as a function of the time of the collision current amount. At this time, when the luminance deterioration coefficient is considered as a numerical value of the degree of deterioration, the function becomes a function that decreases with time with the initial value being 1.0. This luminance deterioration coefficient may be held as a mathematical expression or in the form of a lookup table for time, but a coefficient relating to time is given to the luminance deterioration.

On the other hand, in the pixel to be corrected, it is possible to integrate the amount of current output for each pixel. In the driving method described so far, for example, a case where amplitude value control is performed will be considered. At this time, the element is driven by controlling the time width in accordance with a certain gradation command value while keeping the amplitude value (current amount) constant during a certain driving period. The amount of current emitted at that time is proportional to time. For example, if the information of the time width is accumulated, it can be considered to be equivalent to the time integral of the amount of electrons colliding with the phosphor of a certain pixel. If the integrated amount of each pixel is stored in the integrated amount table, it can be accumulated as current time integrated value information.

Next, at the time of the pixel correcting operation, the luminance deterioration correction coefficient at that time can be obtained from the time integration value information at that time. For example, the elapsed time at the time of correction is 100 hours, and the time integration value information at that time is 10 hours and 30 minutes.
Assume that the luminance deterioration correction coefficient at this time is, for example, 0.98. Next, it is driven by the calculated correction value and multiplied by a coefficient so that the luminance at the time of light emission becomes the reciprocal of the luminance correction coefficient. Specifically, at the time of pulse width control,
Since the time width is proportional to the luminance, the calculated correction value (the value of the time width itself this time) is multiplied by the reciprocal of the luminance deterioration correction coefficient (in this case, 0.98). In the case of a driving method in which the correction value is not proportional to the luminance, the luminance correction coefficient is further calculated. The luminance deterioration correction coefficient may be corrected not only by multiplying the reciprocal but also by addition, subtraction, calculus, or the like according to the characteristics of the element or the driving method.

As described above, by further changing the correction value in consideration of the luminance deterioration characteristics of the phosphor, it is possible to perform luminance correction in consideration of the deterioration of the phosphor. It becomes possible to correct the deterioration with time more accurately.

It should be noted that there is no difference in the time integration amount of the amount of electrons colliding with the phosphor when an average image is output, and it is costly to prepare an integration amount table for every pixel. In the case where the time is up, the time integration information may be simply replaced with the panel drive time.

If the luminance degradation characteristics differ depending on the emission color of the phosphor, a luminance degradation correction coefficient is prepared for each of R, G, and B.

Although the collision current component value is used as a parameter of the phosphor deterioration, the present invention is not limited to this, and any value may be used as long as the degree of deterioration can be estimated.

As described above, by performing such a correction procedure, the luminance can be corrected for all the pixels of the display panel, and the luminance variation can be suppressed.

(Embodiment 9) As Embodiment 9, another example of the operation of the time-dependent change correction will be described. FIGS. 39 and 40 are schematic diagrams showing the order of pixels for performing the correction operation in the correction procedure described above. FIG. 39 shows a method in which pixels to be subjected to luminance correction are sequentially shifted to adjacent pixels.
This is the same order as the video output system used in a normal CRT. This method is only performed sequentially, and the configuration is simplified.

In the operation of sequentially correcting the adjacent pixels, the light emission becomes linear although the light emission period is short, and the light emission may be recognized in a streak shape depending on the timing. In this case, as shown in FIG. 40, instead of sequentially selecting adjacent pixels, luminance correction may be performed by arbitrarily selecting non-adjacent pixels. By doing so, the luminance correction operation cannot be recognized at all.

(Tenth Embodiment) As a tenth embodiment, another example of the operation of the temporal change correction will be described. FIG.
FIG. 5 shows an example of operation intervals of the luminance correction operation. When performing luminance correction by the operation as in the above-described embodiment, re-correction is performed at certain intervals. The interval of the re-correction operation is arbitrarily determined according to the characteristics of the element. According to the present invention, since the luminance correction operation can be performed without being recognized by the user, the correction interval may be any time. For example, it may be performed at regular intervals every 1000 hours.

FIG. 42 shows the life characteristics of the elements constituting the display panel. Although the luminance deteriorates with time, the element characteristic has a degree of deterioration that increases with time as compared with the initial stage. In the case of a display panel having such characteristics, it is possible to minimize the variation in brightness by setting the interval of the brightness correction to be initially long and shortening the interval as time passes.

FIG. 43 shows the life characteristics of the elements constituting the display panel. Also in this characteristic, although the luminance deteriorates with time, the degree of deterioration becomes smaller as time elapses from the initial stage. At this time, if the interval of the luminance correction is initially set to be short, and the interval is increased as time passes, it is possible to minimize the luminance variation.

The interval of the luminance correction operation may be performed at a constant interval, or as described above, the interval of the re-correction operation may be set according to the characteristics of the element.
The luminance variation can be minimized, and the luminance variation can be corrected without being recognized by the user.

As a specific configuration for changing the interval of the luminance correction, a re-correction command calculator 180 shown in FIG. 44 may be used, for example.

(Eleventh Embodiment) As an eleventh embodiment, another example of the operation for correcting the change over time will be described. FIG.
FIG. 5 shows an example of operation intervals of the luminance correction operation. In the present embodiment, the brightness correction operation for the entire screen is continuously performed.
In the above-described embodiment, the re-correction is performed at certain intervals. However, as an advantage of the present invention, since the luminance is corrected during the blanking period, the operation can be performed without being recognized by the user. Therefore, it is possible to continuously correct all pixels without a certain period. At this time, since the correction is always effective, it is possible to perform display without variation in luminance regardless of the degree of luminance degradation.

The luminance correction operation for the entire screen is performed continuously. Among them, the luminance acquisition operation for each pixel is
It may be performed continuously during each video blanking period, or may be performed at an arbitrary timing instead of continuous.

The luminance used in the embodiments described so far is unified with the luminance measured from the front of the panel. However, depending on the conditions, it does not have to be the front, and there is no problem if they are used unified.

Further, according to the above embodiment, in the display panel, a certain pixel is made to emit light, and luminance information (for example, a drive current or an anode current in the case of FED) is taken in, a luminance correction memory is created, and a luminance correction memory is created. By correcting the driving, a display without uneven light emission can be realized for both the initial characteristics and the change with time.

Further, by taking in luminance information of the pixels during the video pause period and updating the correction memory based on the luminance information, it is possible to correct a temporal change without interrupting the video output. Therefore, the correction operation can be performed without the user being conscious of it, and a display panel that can maintain high display quality can be provided.

(Other Matters) (1) When the above-described gradation driving method and luminance correction method are realized, they are generally realized as a driver IC. At this time, an arithmetic circuit for calculating a correction value, a correction value memory, a corrector, a signal driver, and the like may be integrated into one chip. In these circuits, the combination of
It may be formed into a chip, and may be performed according to the application.

(2) A driver IC for realizing gradation
A configuration is also conceivable in which a correction memory is provided in the device to perform correction. In this way, by integrating the functional blocks into one chip, the driver cost can be reduced and the cost can be reduced, and the entire device can be reduced in size and weight.

(3) In an image display device equipped with a display panel, a gradation driving circuit, and a luminance correction circuit that performs the operations described in the above embodiments, gradation can be realized with high accuracy and the initial stage can be improved. In addition, it is possible to provide a small, lightweight, and high-quality image display device that suppresses luminance variation due to aging.

(4) Further, even in a light source equipped with a gradation driving circuit or a luminance correction circuit that performs the operation described in the above embodiment, the luminance setting can be changed, so that appropriate luminance can be obtained. At the same time, the load on the element can be reduced and the life can be extended.

[0215]

As described above, according to the structure of the present invention, it is possible to realize a display mainly without light emission unevenness with time. The individual effects are as follows.

(1) By changing the luminance setting reference value with the elapsed time, the load on the element can be reduced and the life can be extended.

(2) By changing the update interval of the correction memory in accordance with the luminance degradation characteristic, re-correction can be performed at an optimal interval without relying on luminance measurement and determination.

(3) With respect to an apparatus having a phosphor, by performing luminance correction in consideration of the degradation characteristics of the phosphor,
The accuracy of the brightness correction is improved.

(4) By performing the correction operation (driving the pixel and taking in the luminance information) in a period that does not affect the output of the video signal, it is not necessary to interrupt the video display halfway.

(5) In order to realize gradation, in particular, a method of simultaneously performing amplitude value control and time width control, a method of displaying gradation by changing the amplitude value in a direction of increasing the value, and a method of gradation. It is realized by controlling the switching of the data. As a result, a high gradation can be realized and a high-quality image can be output.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a display panel according to Embodiment 1 of the present invention.

FIG. 3 is a circuit diagram of the display panel according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of an output waveform according to the first embodiment of the present invention.

FIG. 5 is a diagram showing an example of an output waveform according to the first embodiment of the present invention.

FIG. 6 is a diagram showing decoder input data according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating an example of an output waveform according to the first embodiment of the present invention.

FIG. 8 is a diagram showing an example of an output waveform according to the first embodiment of the present invention.

FIG. 9 is a diagram illustrating a configuration of a display driver according to the first embodiment of the present invention.

FIG. 10 is a diagram for explaining a luminance capturing operation when the luminance capturing means is a CCD.

FIG. 11 is a diagram showing another configuration when the luminance capturing means is a CCD.

FIG. 12 is a diagram showing a configuration of another luminance capturing unit.

FIG. 13 is a diagram illustrating a configuration of still another luminance capturing unit.

FIG. 14 is a diagram illustrating an example of a detection waveform according to the first embodiment;

FIG. 15 is a diagram illustrating an example of a configuration of a correction circuit according to the first embodiment.

FIG. 16 is a diagram illustrating an example of output characteristics according to the first embodiment.

FIG. 17 is a diagram illustrating an example of output characteristics according to the first embodiment.

FIG. 18 is a diagram illustrating an example of an output waveform according to the first embodiment.

FIG. 19 is a diagram illustrating an example of output characteristics of the first embodiment.

FIG. 20 is a diagram illustrating an example of an output waveform according to the first embodiment.

FIG. 21 is a diagram showing a relationship between applied voltage and luminance.

FIG. 22 is a diagram illustrating an example of an output waveform according to the first embodiment.

FIG. 23 is a diagram illustrating an example of an output waveform according to the first embodiment.

FIG. 24 is a diagram for explaining switching of a gradation realization method.

FIG. 25 is a diagram for explaining switching of another gradation realization method.

FIG. 26 is a diagram illustrating an example of output characteristics of the first embodiment.

FIG. 27 is a diagram illustrating an example of output characteristics of the first embodiment.

FIG. 28 is a diagram showing a luminance correction method according to the second embodiment.

FIG. 29 is a diagram illustrating a luminance correction method according to the third embodiment.

FIG. 30 is a flowchart showing a luminance correction method according to the fourth embodiment.

FIG. 31 is a flowchart showing a luminance correction method according to the fifth embodiment.

FIG. 32 is a diagram illustrating a relationship between a luminance current and a drive voltage for describing a luminance correction method according to the sixth embodiment.

FIG. 33 is a diagram illustrating a relationship between a luminance current and a drive voltage for describing a luminance correction method according to the sixth embodiment.

FIG. 34 is a diagram illustrating deterioration characteristics of a phosphor for describing a luminance correction method according to the seventh embodiment.

FIG. 35 is a diagram showing an example of a configuration for realizing the luminance correction method according to the seventh embodiment.

FIG. 36 is a diagram showing deterioration characteristics of a phosphor.

FIG. 37 is a flowchart showing a luminance correction method according to the eighth embodiment.

FIG. 38 is a diagram showing an example of a configuration for realizing the luminance correction method according to the eighth embodiment.

FIG. 39 is a diagram showing a luminance correction method according to the ninth embodiment.

FIG. 40 is a diagram showing a luminance correction method according to the ninth embodiment.

FIG. 41 is a diagram illustrating a luminance correction method according to the tenth embodiment.

FIG. 42 is a diagram showing the life characteristics of the elements constituting the display panel.

FIG. 43 is a diagram showing the life characteristics of the elements constituting the display panel.

FIG. 44 is a diagram showing an example of a configuration for realizing the luminance correction method according to the tenth embodiment.

FIG. 45 is a diagram showing a luminance correction method according to the eleventh embodiment.

FIG. 46 is a configuration diagram of a conventional basic display.

FIG. 47 is a configuration diagram of a conventional PWM system.

FIG. 48 is a diagram showing an example of a conventional PWM light emission pattern.

FIG. 49 is a configuration diagram of a conventional output modulation method.

FIG. 50 is a diagram showing an example of a light emission pattern of a conventional output modulation method.

FIG. 51 is a diagram illustrating an example of a conventional luminance correction method.

FIG. 52 is a view for explaining a conventional gradation control method.

[Explanation of symbols]

 Reference Signs List 1 Video decoder 2 Controller 3 ADC 4 Corrector 5 Correction value memory 6 Correction value calculator 7 Signal driver 8 Scan driver 9 Display panel 10 Anode current measuring means 12 Correction circuit 57 Brightness capturing means 100 Brightness set value generator 180 Recorrection command Arithmetic unit 190 Phosphor degradation arithmetic unit

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G09G 3/22 G09G 3/22 D 3/30 3/30 K H04N 5/66 H04N 5/66 A (72) Inventor Koji Akiyama 1006 Kazuma Kadoma, Kadoma City, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Tetsuya Shiratori 1006 Kadoma Kadoma, Kadoma City, Osaka Pref. BA13 BA32 BA35 BB05 BB14 5C080 AA01 AA06 BB05 DD05 DD13 EE19 EE29 JJ02 JJ03 JJ04 JJ05 JJ06 JJ07

Claims (70)

[Claims] 1. A method for driving a display panel, comprising: setting a luminance twice or more, performing a luminance setting operation in which respective luminance setting values are different, and changing the set luminance with a driving time. 2. The display panel according to claim 1, wherein the brightness setting value is determined based on measured brightness information, and the brightness is corrected so as to match the determined setting brightness value. Drive method. 3. A pixel is driven, luminance information of the pixel is taken in, a correction value is calculated from the measured luminance information and a luminance set value, and the correction value is stored in the correction memory. Is a driving method of a display panel that corrects a driving amount according to the following formula:
A method for driving a display panel, comprising: performing a brightness setting operation such that each set brightness value is different, and changing the set brightness with a drive time. 4. The method according to claim 1, wherein the luminance setting value does not exceed a previous luminance setting value. 5. The method according to claim 1, wherein the luminance is corrected at least twice in accordance with a predetermined interval, and a luminance correction operation in which the intervals of the respective luminance correction operations are different is performed, thereby changing a start interval of the re-correction operation. Driving method of the display panel. 6. The display panel driving method according to claim 5, wherein an interval of the luminance correction operation is changed according to a luminance deterioration characteristic of the display element. 7. A pixel is driven, luminance information of the pixel is taken in, a correction value is calculated from the measured luminance information and a luminance set value, the correction value is stored in a correction memory, and the correction value is further stored in accordance with the correction memory. A method of driving a display panel for correcting a driving amount, wherein a series of updating operations of the correction memory in all pixels are performed at predetermined intervals. 8. The method of driving a display panel according to claim 7, wherein a series of operations for updating the correction memory is performed continuously, instead of being performed at the predetermined interval. 9. The method according to claim 2, wherein the operation of correcting the luminance is performed during a period other than the video output period. 10. The display panel driving method according to claim 3, wherein the operation of capturing the luminance information of the pixel is performed by causing at least the pixel to emit light during a period other than the video output period. 11. A period other than the video output period is a vertical blanking period, and luminance information is taken in a set number of pixels within the period.
0. A method for driving a display panel according to item 0. 12. The method according to claim 10, wherein adjacent pixels are not driven continuously. 13. The display panel according to claim 3, wherein the calculation of the correction value is performed using both the measured luminance information and the deterioration characteristic relating to the luminance of the element or pixel for which the luminance was measured. Drive method. 14. A method for driving a display panel having a light emitting surface having a phosphor, wherein a degradation characteristic relating to the luminance of the phosphor is used in place of the degradation characteristic relating to the luminance of the element or the pixel. Item 14. A method for driving a display panel according to item 13. 15. A deterioration characteristic is measured in advance, a degree of deterioration is calculated based on a driving integration amount for each pixel, and a correction value is calculated using both the measured luminance information and a correction memory. The method of driving a display panel according to claim 13, wherein the updating is performed. 16. The display panel driving method according to claim 2, wherein the correction operation is continued until the difference between the measured luminance information and the luminance set value becomes equal to or less than a certain value. 17. The method according to claim 3, wherein the luminance information to be taken is a drive current. 18. The method according to claim 3, wherein the luminance information to be taken is a light emission start point of the pixel. 19. A luminance correction method for a display panel in which the display panel has at least an anode electrode and a light emitting surface having a plurality of phosphors on the anode electrode, wherein the luminance information to be taken is an anode current. Claim 3
The driving method of the display panel described in the above. 20. Initially, when a display panel is formed,
For all the constituent pixels, the pixels are made to emit light one pixel at a time, the luminance information of the pixels is captured, and the luminance setting operation is performed twice or more and the luminance setting values are different from each other. A method of calculating a correction value from the obtained luminance information and the luminance setting value, and storing the correction value in a correction memory as an initial correction value. 21. The display panel driving method according to claim 3, wherein an input luminance signal is corrected according to a correction value stored in the correction memory. 22. The display panel driving method according to claim 3, wherein an amplitude value or a time width of a driving signal applied to the display panel is corrected according to the correction value stored in the correction memory. 23. The display panel driving method according to claim 3, wherein the correction memory calculates and stores a correction value which also has γ correction data for each pixel. 24. The display panel according to claim 3, wherein the gradation is realized by amplitude control or time width control.
3. The method for driving a display panel according to item 1. 25. A method for realizing a gray scale of a display panel, which is a gray scale method in which a current or a voltage value for amplitude value control is changed only in a direction of increasing the current value except when the output is terminated. 3. The method for driving a display panel according to item 3. 26. The display panel driving method according to claim 3, wherein the gray scale realizing method of the display panel is a driving method of simultaneously performing amplitude value control and time width control. 27. The gradation control method according to claim 1, wherein upper-order m bits (m is an arbitrary integer) of the gradation data represented by n bits (n is an arbitrary integer) at intervals of 1/2 m of a maximum value. Amplitude value control that outputs a current or voltage value whose amplitude is controlled, and time width control that controls the time width at intervals of 1/2 ^(nm) of the maximum value using lower ^(nm) bits are performed. The method of driving a display panel according to claim 26, wherein 28. The LSB of current or voltage output is set to 2
28. The display panel driving method according to claim 26, wherein LSB having an output time width is output twice, or both LSBs are output twice. 29. The output division number of the time width control is larger than the output division number of the amplitude value control.
7. The method for driving a display panel according to item 6. 30. A gray scale realizing method for a display panel is a driving method for realizing gray scale by switching between amplitude value control or time width control and a gray scale control method for simultaneously performing amplitude value control and time width control. The method for driving a display panel according to claim 3, wherein: 31. A gradation for performing amplitude value control or time width control when the magnitude of the output luminance signal level is equal to or less than a reference value, and performing amplitude value control and time width control simultaneously when the magnitude of the output luminance signal level is equal to or greater than the reference value. 31. The driving method of a display panel according to claim 30, wherein a gray scale is realized by performing a control method. 32. The method according to claim 31, wherein the reference value is the number of output gray scales, and has means for setting the number of gray scale steps on the time width control side in a gray scale control method for simultaneously performing amplitude value control and time width control. 32. The method for driving a display panel according to claim 31, wherein: 33. The display panel driving method according to claim 30, wherein the gray scale is realized by switching a gray scale realization method depending on time. 34. A luminance resetting means for setting a luminance twice or more and performing a luminance setting operation such that the respective luminance setting values are different, wherein the setting luminance is changed with the driving time. Brightness correction device. 35. A system comprising: a luminance correcting unit that corrects luminance so as to match a luminance setting value; and a unit that determines the luminance setting value based on measured luminance information. 35. The brightness correction device according to claim 34. 36. A luminance resetting means for setting a luminance twice or more and performing a luminance setting operation such that respective luminance setting values are different, a driving means for driving a pixel, and a luminance measurement for taking in luminance information of the pixel. Means, a correction memory for storing a correction value, a calculation means for calculating a correction value from the measured luminance information and the luminance set value, and storing the correction value in the correction memory, and correcting a driving amount according to the correction memory. A brightness correction device for a display panel. 37. The brightness correction apparatus according to claim 34, wherein the brightness setting value does not exceed a previous brightness setting value. 38. A brightness correction means for correcting brightness at least twice in accordance with a predetermined interval and performing a brightness correction operation in which the intervals between the brightness correction operations are different. A brightness correction device characterized by changing. 39. A display device comprising:
39. The brightness correction apparatus according to claim 38, further comprising: means for changing an interval of the brightness correction operation. 40. A driving unit for driving a pixel, a luminance measuring unit for taking in luminance information of the pixel, a correction memory for storing a correction value, and calculating a correction value from the measured luminance information and a luminance set value. A calculating unit for storing the correction value in the correction memory; a correcting unit for correcting a driving amount according to the correction memory; and a control unit for performing a series of updating operations of the correction memory in all pixels at predetermined intervals. A brightness correction device for a display panel, comprising: 41. The display panel according to claim 40, wherein the control means continuously performs a series of update operations of the correction memory, instead of performing the update operation at the predetermined interval. Correction device. 42. The brightness correction apparatus according to claim 35, further comprising control means for controlling the brightness correction operation to be performed during a period other than the video output period. 43. The display according to claim 40, further comprising control means for controlling the operation of capturing the luminance information of the pixel by causing at least the pixel to emit light during a period other than the video output period. Panel brightness correction device. 44. A method according to claim 43, wherein the predetermined period other than the video output period is a vertical blanking period, and a luminance 1 blue report is taken in a set number of pixels within the period. A brightness correction device for a display panel as described in the above. 45. The apparatus according to claim 43, wherein the control unit does not cause adjacent pixels to emit light continuously. 46. An operation for calculating a correction value by using both measured luminance information and a deterioration characteristic relating to the luminance of an element or a pixel whose luminance has been measured, and updating a correction memory instead of the arithmetic means. 37. The apparatus according to claim 36, further comprising a correction unit. 47. A brightness correction device for a display panel having a light emitting surface composed of a phosphor, wherein the arithmetic correction means uses the degradation characteristic of the phosphor instead of the degradation characteristic of the element or the pixel. 47. The brightness correction device for a display panel according to claim 46, wherein the brightness correction device is used. 48. The deterioration characteristic is measured in advance, the degree of deterioration is calculated based on the integrated amount of drive current for each pixel, and a correction value is calculated using both the measured luminance information and a correction memory. 47. The display panel brightness correction apparatus according to claim 46, further comprising an operation correction unit for updating the luminance of the display panel. 49. The display panel according to claim 35, further comprising control means for controlling so as to continue the correction operation until the difference between the measured luminance information and the luminance set value becomes equal to or less than a certain value. Brightness correction device. 50. The display panel brightness correction apparatus according to claim 36, further comprising brightness measurement means whose brightness information to be taken is a drive current. 51. The apparatus according to claim 3, further comprising a luminance measuring unit whose luminance information to be taken is a light emission start point of the pixel.
7. The luminance correction device for a display panel according to 6. 52. A brightness correction apparatus for a display panel, wherein the display panel has at least an anode electrode and a light emitting surface having a plurality of phosphors on the anode electrode, wherein the brightness information to be taken is an anode current. 37. The brightness correction device for a display panel according to claim 36, wherein: 53. A luminance resetting means for setting a luminance twice or more and performing a luminance setting operation such that respective luminance setting values are different, and one pixel for all pixels constituting the display panel at the initial stage of forming the display panel. Control means for causing a pixel to emit light at a time, fetching luminance information of the pixel, calculating a correction value from the luminance information and a luminance set value, and storing the correction value in a correction memory as an initial correction value. A brightness correction device for a display panel, comprising: 54. The apparatus according to claim 36, wherein the correcting means for correcting the drive amount in accordance with the correction value stored in the correction memory corrects an input luminance signal. 55. A correcting means for correcting a drive amount according to a correction value stored in the correction memory, corrects an amplitude value or a time width of a drive signal applied to a display panel according to the correction value stored in the correction memory. 37. The brightness correction device for a display panel according to claim 36, wherein: 56. A display panel drive device comprising the display panel luminance correction device according to claim 36, wherein the display panel gradation realizing method is amplitude value control or time width control. 57. A display panel brightness correcting method according to claim 36, wherein the display panel gradation realizing method is performed only in the direction of increasing the current or voltage value of the amplitude value control except when terminating the output. A driving method of a display panel, wherein the driving method is a gradation method in which the display panel is changed to a gray scale. 58. A display panel comprising the display panel luminance correction device according to claim 36, wherein the display panel gradation realizing method is a driving method for simultaneously performing amplitude value control and time width control. Gradation driving device. 59. The gradation control is performed at intervals of 1/2 m of a maximum value using upper m bits (m is an arbitrary integer) of gradation data expressed by n bits (n is an arbitrary integer). Amplitude value control that outputs a current or voltage value whose amplitude is controlled, and time width control that controls the time width at intervals of 1/2 ^(nm) of the maximum value using lower ^(nm) bits are performed. The driving device of a display panel according to claim 58, wherein 60. The LSB of current or voltage output is 2
59. The display panel driving device according to claim 58, wherein the LSB having the output time width is output twice or the LSB having the output time width is output twice. 61. The output division number of the time width control is larger than the output division number of the amplitude value control.
9. The display panel driving device according to 8. 62. A method for realizing a gradation of a display panel, comprising the luminance correction device for a display panel according to claim 36, wherein the amplitude control or the time width control and the amplitude value control and the time width control are simultaneously performed. A driving device for a display panel, wherein the driving method is a driving method for realizing gradation by switching between a tone control method. 63. A gray scale for performing amplitude value control or time width control when the magnitude of the output luminance signal level is equal to or less than a certain reference value, and performing amplitude value control and time width control when the magnitude of the output luminance signal level is equal to or more than the reference value. 63. The display panel driving device according to claim 62, further comprising means for performing a gray scale by performing a control method. The reference value is the number of output gray scales, and has means for setting the number of gray scale steps on the time width control side in a gray scale control method for simultaneously performing amplitude value control and time width control. 64. The display panel driving device according to claim 63. 65. The display panel driving device according to claim 62, further comprising means for switching the gray scale realization method depending on time to realize gray scale. 66. The display panel driving device according to claim 56, wherein the correction memory has a value corresponding to the number of steps of the amplitude value for each pixel. 67. The display panel driving device according to claim 56, wherein the correction memory has a value which also has data for γ correction for each pixel. 68. A brightness correction apparatus according to claim 36, wherein at least two of said correction memory, said correction means, said calculation means, and said control means are integrated. Display panel driving device. 69. An image display device comprising the luminance correction device according to claim 36. 70. A light source comprising the luminance correction device according to claim 36.