JP2011253056A - Image display device and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for displaying an image at short time whose luminance variation is suppressed without increasing a processing band of a work memory.SOLUTION: An image display device of the present invention comprises: a display panel; first memory means for storing correction data; second memory means; transmission means for transmitting the correction data; correction means for reading the correction data from the second memory means and performing a correction process on an input image signal; and control means. The control means starts a temporary correction process using a part of the correction data when the part of the data is written in the second memory means as well as starts an image display, and by abbreviating the temporary correction process on a part of frames until the rest of the data is written in the second memory means, generates non-read time in which the correction means does not access the second memory means to allocate the non-read time to a process for the transmission means writing the rest of the data in the second memory means.

Description

  The present invention relates to an image display device and a control method thereof.

Conventional techniques relating to image display devices are disclosed in, for example, Patent Documents 1 and 2.
Japanese Patent Application Laid-Open No. 2004-228688 shows to a user that a start-up operation is transmitted to a device by displaying a predetermined still image or moving image on the screen from when the start-up operation is performed until normal image output starts. A technique for recognizing is disclosed.
Patent Document 2 discloses a technique for shortening the apparent processing time by displaying a narrowband broadcast before a wideband broadcast having a long processing time until display.

JP 2007-104083 A JP 2008-187379 A

As an image display device, in particular, as a flat display device (FPD), a liquid crystal display device (LCD), a plasma display device (PDP), a field emission display device (FED), an organic EL display device (OLED), etc. are known. Yes.
In such an FPD, it is necessary to form a large number of display elements on a substrate. The light emission characteristics of these display elements are affected by slight differences in manufacturing conditions and the like. Therefore, in general, it is difficult to make the light emission characteristics of all the display elements included in the FPD completely uniform. This non-uniformity of the light emission characteristics causes a luminance variation and causes image quality deterioration. For example, in the case of an FED, a surface conduction electron-emitting device, a Spindt type, an MIM type, a carbon nanotube type, or the like is used as an electron-emitting device. If the shape or the like of the electron-emitting device varies depending on the manufacturing conditions of the electron-emitting device, the electron-emitting characteristics of the electron-emitting device also differ. As a result, luminance variation occurs and image quality deteriorates.

  In response to such a problem, a configuration for correcting a video signal in accordance with the light emission characteristics of each display element has been proposed (luminance variation correction). For example, there is a method in which correction data including an adjustment ratio (correction value) for reducing luminance variation is prepared in advance for each display element, and the luminance variation is reduced by multiplying the input video signal by the adjustment rate. However, the luminance variation may depend on the gradation value (gradation dependence of variation). Therefore, in order to reduce the luminance variation for all the gradation values, it is necessary to prepare correction values corresponding to the respective gradation values for each display element, and the amount of correction data becomes enormous. In addition, this capacity further increases as the image display device becomes higher in definition.

  On the other hand, the correction data described above must be retained even when the image display apparatus is turned off, and is generally retained in a nonvolatile memory (storage memory) such as a flash memory. In addition, since the non-volatile memory is slower than the processing rate of the video processing, every time the image display device is turned on, the non-volatile memory changes from a non-volatile memory to a high-speed volatile memory such as a DRAM for correcting luminance variation ( It is necessary to transfer the correction data to the work memory. Therefore, due to an increase in the transfer capacity (the correction data capacity described above), the above transfer takes time, the start-up time of the image display device (time until video is displayed), and a digital television to which the image display device is applied. The start-up time for the set will be longer.

To solve this problem, several methods for shortening the startup time can be considered.
One is a method of reducing or compressing the correction data capacity. However, it is not appropriate to reduce the capacity of the correction data because the image quality after correction (the degree of reduction in luminance variation) is significantly reduced. In addition, since the luminance variation is generally random, the correlation of the correction data is low, and the compression rate cannot be improved.
The other is a method of increasing the transfer speed by parallel processing using a plurality of nonvolatile memories. This method is not appropriate because it is very expensive.

  In addition, the techniques disclosed in Patent Documents 1 and 2 are both techniques for suitably shortening the activation time due to decoding of broadcast signals and the like, and are not techniques for shortening the activation time due to transfer of correction data. . For this reason, even if the techniques disclosed in Patent Documents 1 and 2 are used, the startup time resulting from the transfer of correction data cannot be shortened.

  An object of the present invention is to provide a technique for displaying an image with reduced luminance variation in a short time without increasing the processing bandwidth of the work memory.

  An image display device according to the present invention stores a display panel having a plurality of display elements arranged in a matrix and correction data used in a correction process for reducing luminance variation between the plurality of display elements. Storage means; second storage means used as a work memory; transfer means for transferring the correction data from the first storage means to the second storage means; and reading the correction data from the second storage means for input A correction unit that performs the correction process on the video signal that has been processed, and a control unit, wherein the control unit writes a part of the correction data to the second storage unit by the transfer unit At the time, the correction means starts a provisional correction process using the partial data, starts displaying video on the display panel, and the transfer means starts the correction. After the remaining data is written to the second storage means, the correction process by the correction means is switched to the correction process using all of the correction data, and the partial data is written to the second storage means. In the period from when the remaining data is written to the second storage means, the correction means eliminates the provisional correction processing for some frames of the input video signal, so that the correction means (2) A non-reading time that does not access the storage unit is generated, and the non-reading time is allocated to a process in which the transfer unit writes the remaining data in the second storage unit.

  An image display apparatus control method according to the present invention stores a display panel having a plurality of display elements arranged in a matrix and correction data used in correction processing for reducing luminance variations among the plurality of display elements. First storage means for performing the operation, second storage means used as a work memory, transfer means for transferring the correction data from the first storage means to the second storage means, and reading the correction data from the second storage means. And a correction unit that performs the correction process on the input video signal, wherein a part of the correction data is written to the second storage unit by the transfer unit. At the time, the provisional correction processing using the partial data is started by the correction means, and the video display on the display panel is started. After the remaining data of the correction data is written in the second storage unit by the transfer unit, the correction process by the correction unit is switched to the correction process using all of the correction data; and the partial data The provisional correction processing for a part of the frames of the input video signal is omitted in the period from when the second data is written to the second memory means until the remaining data is written to the second memory means. Generating a non-reading time during which the correction unit does not access the second storage unit, and allocating the non-reading time to a process in which the transfer unit writes the remaining data to the second storage unit. It is characterized by having.

  According to the present invention, an image with reduced luminance variation can be displayed in a short time without increasing the processing bandwidth of the work memory.

FIG. 3 is a diagram illustrating an example of a startup sequence according to the first embodiment. The figure which shows an example of the whole structure of the image display apparatus which concerns on a present Example. The figure which shows an example of a modulation signal. The figure which shows an example of the characteristic of an electron emission element. The figure which shows an example of the gradation dependence of a correction value. The figure which shows an example of a structure of the brightness variation correction part which concerns on a present Example. The figure which shows the flow of a process of the conventional system control part. The figure which shows the conventional starting sequence. FIG. 3 is a diagram illustrating an example of a process flow of a system control unit according to the first embodiment. The figure which shows the subject of the memory access at the time of provisional correction processing. FIG. 10 is a diagram illustrating a startup sequence according to the second embodiment. The figure which shows an example of the luminance variation distribution before correction | amendment, and a target luminance value.

  According to the present invention, an image with reduced luminance variations (brightness variations among a plurality of display elements) can be displayed in a short time without increasing the processing bandwidth of the work memory. For example, shortening the start-up time (time until video display) due to transfer of correction data used for correction processing (luminance variation correction) for reducing luminance variation without increasing the processing bandwidth of the work memory Can do. Further, when the luminance variation depends on the gradation value, the correction data capacity increases, so that the effect of the present invention can be greatly expected.

  The drive (modulation) method of the image display device is not particularly limited, but the drive method for controlling the voltage waveform is preferable because the luminance variation depends on the gradation value. For example, an active matrix driving type or a simple matrix driving type is preferable. Specifically, a voltage-driven pulse width modulation method (PWM), a pulse amplitude modulation method (PHM), a combination type of PWM and PHM, a current-driven type (resulting in a change in the voltage waveform applied to the display element) Is preferable). In particular, a PHM that modulates the amplitude (electric field strength) of a modulation signal in accordance with a gradation value, a combined type of PWM and PHM, and the like are preferable because gradation dependency of luminance variation becomes remarkable.

  The kind of display element used in the present invention is not particularly limited. For example, an electron-emitting device, an EL device, a liquid crystal device, a plasma device, or the like can be used. In particular, an electron-emitting device or an EL device whose luminance is controlled by electric field strength can be preferably used from the viewpoint of gradation dependency of luminance variation. As the electron-emitting device, for example, a surface conduction type, Spindt type, MIM type, carbon nanotube type, or BSD type electron-emitting device can be used.

  In a large-area image display device using a plurality of display elements, variation in emission current among the plurality of display elements tends to be large, and thus uneven brightness (luminance variation) is likely to occur. For this reason, an image display device having a large area (a diagonal size of a screen of 20 inches or more) using a plurality of display elements is a preferable embodiment to which the present invention is applied. In a high-definition image display device, since the capacity of correction data increases, the transfer capacity (and time required for transfer) also increases. Therefore, a high-definition (high-definition resolution such as 2K1K or 4K2K) image display device is a preferable form to which the present invention is applied.

Further, it is necessary to store the correction data in a non-volatile memory such as a flash memory even when the image display apparatus is turned off. When starting up or switching the display mode, it is necessary to transfer from a low-speed nonvolatile memory to a high-speed volatile memory such as a DRAM for correcting luminance variation. Therefore, a system in which correction data must be transferred between two memories, a memory for storing correction data (storage memory) and a memory for processing (work memory), a system having a low transfer speed, and the like are disclosed in the present invention. Is a preferred form to which is applied.
Further, a method of selecting and reading out only a minimum necessary correction value from a plurality of correction values corresponding to a plurality of gradation values stored in the work memory is a preferable form to which the present invention is applied.

<Example 1>
Hereinafter, an image display apparatus and a control method thereof according to Embodiment 1 of the present invention will be described. In this embodiment, an example in which an electron-emitting device is used as a display device and the electron-emitting device is driven in a simple matrix by a modulation method including PWM will be described. In this embodiment, correction data is prepared for each of a plurality of display elements, and the correction data for one display element is N (N is an integer of 2 or more) corresponding to N gradation values. It is assumed that it is composed of correction values. However, as described above, the present invention is not limited to this configuration.

  1 and 2 are representative views for explaining an image display apparatus and a control method thereof according to the present embodiment. FIG. 1 is a diagram illustrating an example of a sequence (start-up sequence) at startup of the image display apparatus according to the present embodiment, and FIG. 2 is a block diagram illustrating an example of the overall configuration of the image display apparatus according to the present embodiment. It is.

(About the entire display controller)
First, the functional configuration of the image display apparatus according to the present embodiment will be described with reference to FIG.
Reference numeral 200 denotes a display panel. The display panel has a plurality of display elements arranged in a matrix. In this embodiment, a display panel in which a rear plate and a face plate are opposed to each other via a support member called a spacer is used as the display panel. The rear plate has a multi-electron source (for example, horizontal direction 5759 (= 1920 × RGB) × vertical direction 1080 electron-emitting devices 214) in which a plurality of display elements (for example, cold cathode elements) are arranged in a matrix. It was supposed to be. The face plate has a glass substrate, a plurality of phosphors provided on the glass substrate so as to face the plurality of electron-emitting devices, and a metal back covering the plurality of phosphors.

  The plurality of electron-emitting devices 214 are simply matrix-wired by a plurality of modulation wires 212 and a plurality of scanning wires 213. By applying signals from the modulation driver 210 and the scanning driver 211 to the modulation wiring 212 and the scanning wiring 213, electrons are emitted from a desired electron-emitting device. By using the high voltage power source 216 to raise the potential of the metal back, the emitted electrons are accelerated and pass through the metal back and collide with the phosphor. Thereby, the phosphor emits light and an image (video) is displayed. The configuration and manufacturing method of a display panel having a plurality of electron-emitting devices are disclosed in detail in, for example, Japanese Patent Application Laid-Open No. 2000-250463.

  Next, processing of the image display apparatus according to the present embodiment, particularly processing from when a video signal is input until video is displayed will be described. The image display device is connected to, for example, a video signal supply device, and mainly performs processing using a video signal such as the video signal S1 and the synchronization signal T1 and processing using a command signal such as the communication signal C1. It consists of two types of parts to be performed.

First, a process from the generation of the video signal S1 input from the video signal supply device to the generation of the drive signal S6 input to the modulation driver 210 will be described.
The video signal S1 is input to the RGB input unit 201. The RGB input unit 201 is a conversion circuit that converts the video signal S1 so that the horizontal resolution, the number of scanning lines, the frame rate, the clock frequency, and the like match those of the display panel 200, and an adjustment that adjusts color temperature, white balance, and the like. Circuit and the like. The RGB input unit 201 performs a predetermined process on the video signal S1 using the conversion circuit and the adjustment circuit, and outputs the processed signal as a signal S2.

The signal S2 is input to the inverse γ correction unit 202. The inverse γ correction unit 202 converts the signal S2 so that the luminance value (output value) on the display panel and the value (data) of the video signal are linear, and outputs the signal S3. In the converted signal S3, the data is proportional to the luminance value, and hence the data of the signal S3 is hereinafter referred to as “luminance data”. In general, the video signal S1 is transmitted or recorded after being subjected to non-linear conversion (gamma conversion) such as 0.45 to match the input-light emission characteristics of the CRT display on the assumption that the video signal S1 is displayed on the CRT display device. ing. The inverse γ correction unit 202 displays such a video signal on a display device having a linear input-light emission characteristic such as FED or PDP, and performs inverse gamma conversion such as a square of the video signal. Apply.

  The signal S3 is input to the luminance variation correcting unit 203, which is a feature of the present embodiment. The luminance variation correction unit 203 performs a correction process for reducing the luminance variation (variation in electron emission characteristics among the plurality of electron-emitting devices 214) on the signal S3, and outputs the signal S4. Details of the luminance variation correction unit 203 will be described in detail later. Since the data of the signal S4 is data in which the luminance variation is corrected, the data is hereinafter referred to as corrected luminance data.

  The signal S4 is input to the phosphor correction unit 204. The phosphor correction unit 204 takes into consideration the nonlinearity of the modulation driver 210, the luminance saturation characteristic of the phosphor, and the like, so that the selected display element emits light at a luminance proportional to the correction luminance data. ) Is subjected to linearity correction and output as a signal S5. In the present embodiment, an electron-emitting device that is not a self-luminous type is assumed as the display device. Therefore, the signal S4 is used so that the phosphor facing the selected electron-emitting device emits light with a luminance proportional to the corrected luminance data. Is subjected to linearity correction. If the luminance saturation characteristics of the phosphors of R, G, and B are different, different conversion (correction) may be performed on the corrected luminance data for each color.

The signal S5 is input to the drive conversion unit 205. The drive conversion unit 205 rearranges the data (signal S5 data) input in RGB parallel so as to correspond to the array of RGB phosphors of the display panel 200. Further, the drive conversion unit 205 converts the data of the signal S5 into data suitable for the input format (eg, Mini LVDS, RSDS, etc.) of the modulation driver 210, and outputs the data as the drive signal S6. The data of the signals S4 and S5 is data having a value proportional to the luminance, but the data of the drive signal S6 is non-linear data with respect to the luminance.

Note that the operation timing of each signal processing unit (function indicated by reference numerals 201 to 205) is controlled by a synchronization signal T2 generated by the timing control unit 206 based on the synchronization signal T1 received from the video signal supply device. The operation mode of each signal processing unit (functions indicated by reference numerals 201 to 205) is controlled by the system control unit 207 by setting each parameter via the system bus 209. The system control unit 207 may be configured with only logic logic, or may be configured with a CPU, a microcomputer, and a media processor capable of parallel operation. The program for performing control may be built in the ROM, or may be transferred from the outside via an input / output interface. The above parameters vary from those having a small data capacity to those having a large data capacity, which is a problem in this embodiment. In any case, the parameters need to be stored even when the power is shut off. There is. Therefore, the above parameters are stored in a large-capacity nonvolatile memory 208 (storage memory; first storage means) represented by a flash memory and the like, and are read out and set by the system control unit 207 as necessary. Can be done. The nonvolatile memory 208 is not limited to a NAND type or NOR type flash memory, but may be a ROM or a hard disk. Moreover, the structure which uses volatile memories, such as SRAM, like a non-volatile memory by battery drive may be sufficient.
In addition, the system control unit 207 receives various requests such as a start request and an operation mode switching request from the video signal supply device side by the communication signal C1, and controls the image display device according to the request if there is no error. When there is an error, the video signal supply device side is notified of this, and error processing (for example, forced shutdown) of the image display device is performed in a fail-safe manner.

Next, a process from when the drive signal S6 is output from the drive conversion unit 205 to when the display panel 200 is driven until video display is performed will be described.
The modulation driver 210 receives the drive signal S6 from the drive conversion unit 205. Then, the modulation driver 210 applies the modulation signal S7 to the modulation wiring 212 for each scanning wiring selection period by the scanning driver 211 based on the timing control signal T3 from the timing control unit 206.
The scanning driver 211 sequentially selects lines (scanning wirings) in accordance with the timing control signal T4 from the timing control unit 206, and applies a predetermined selection signal to the selected scanning wirings during the selection period.
The drive power source 215 supplies power for driving the modulation driver 210 and the scan driver 211.

  Thus, the modulation driver 210 drives the modulation wiring 212 with the modulation signal corresponding to the drive signal S6. At the same time, the scanning driver 211 outputs a selection potential (scanning pulse) to the scanning wiring 213. Thereby, the electron-emitting device 214 connected to the selected scanning wiring 213 and the modulation wiring 212 to which the modulation signal is applied emits electrons according to the modulation signal of the modulation wiring 212.

The high-voltage power supply 216 generates an acceleration voltage (8 to 10 kV), and makes the metal back potential high by the acceleration voltage. Thereby, the electrons emitted from the electron-emitting device are accelerated and collide with the phosphor. The phosphor emits light by the collision of electrons with the phosphor.
By sequentially selecting all the scanning wirings and performing the above processing, an image for one screen is formed (displayed) on the display panel 200.
The drive power source 215 and the high voltage power source 216 are preferably configured to be adaptively controlled by control signals C2 and C3 from the system control unit 207. In particular, it is preferable to control the driving sequence of each power source and the step-up / step-down method of the high-voltage power source with an appropriate startup / shutdown sequence at the time of start-up, power-off, and error occurrence.

(Necessity of multi-value correction)
Next, the reason why the multi-value correction is necessary in the luminance variation correction unit 203 will be described below. Multi-value correction means correction processing using correction values corresponding to at least two or more gradation values with respect to luminance variations that differ for each gradation value.

First, an example of the modulation signal of the modulation driver 210 will be described. Since the electron-emitting device can control the emission current according to the drive voltage to be applied, the luminance can be controlled by the pulse amplitude of the modulation signal. Also, the luminance can be controlled by the pulse width of the modulation signal.
In this embodiment, a case where a display panel is driven by a method of modulating a pulse width and a pulse amplitude as shown in FIG. 3 will be described. In FIG. 3, the modulation signal waveform (drive waveform) corresponding to each gradation value is shown side by side with the vertical axis representing potential and the horizontal axis representing time. Here, the gradation value is a number assigned in descending order of the signal level that can be taken by the modulation signal.
This corresponds to the drive signal S6 output from 05.

  In such a modulation method, the smaller the difference in pulse width and pulse amplitude between the driving waveform of the target gradation value and the driving waveform corresponding to the preceding and subsequent gradation values, the lower the gradation at the target gradation value. Increases performance. Further, in the present modulation method, the difference can be reduced in a low luminance region (low gradation region; region having a small gradation value) as compared with a PWM modulation method in which the pulse amplitude is constant. Therefore, the number of gradation values in the low gradation region can be increased (the gradation performance in the low gradation region can be improved). However, in this modulation method, since the pulse amplitude is lower on the low gradation side than in the case of normal PWM, the luminance variation increases on the low gradation side. Hereinafter, the gradation dependency of such luminance variation will be described in detail.

  As a result of intensive studies by the present inventors on the cause of the luminance variation, it has been found that the luminance variation is largely due to variations in the emission current among a plurality of electron-emitting devices. FIG. 4 shows a schematic graph of the characteristics of the electron-emitting device with the horizontal axis representing the driving voltage and the vertical axis representing the emission current. The drive voltage is a voltage (Vf) applied to the electron-emitting device 214, and is a difference (Vf = VA + Vss) between the potential (−Vss) of the selection signal and the potential (VA) of the modulation signal. FIG. 4 is a diagram when the potential (−Vss) of the selection signal is −7.5V and the maximum value of the potential (VA) of the modulation signal is 7V. It can be seen from FIG. 4 that electrons are emitted from the electron-emitting device to which the selection signal is applied in accordance with the potential (VA) of the modulation signal. On the other hand, it can be seen that electrons are not emitted from the electron-emitting device to which the selection signal, the modulation signal, or both are not applied.

  In the actual display panel 200, there are not a few variations in characteristics among a plurality of electron-emitting devices. FIG. 4 schematically shows the characteristics of two electron-emitting devices as an example. In FIG. 4, a portion indicated by A is a portion where the potential of the modulation signal is high, and the emission current values are relatively coincident between the two elements. On the other hand, the portion indicated by B is a portion where the potential of the modulation signal is lower than that of the portion A, and it can be seen that the emission current value greatly deviates (varies) between the two elements. Further, in the driving voltage between the part A and the part B, the emission current value between the two elements is not as large as the part B, but is larger than the part A. This variation in the emission current value causes a luminance variation among a plurality of display elements. In addition, the variation in the emission current value depending on the value of the drive voltage causes the gray level dependency of the luminance variation.

  Further, when the number of emission points (number of electron emission positions) varies among a plurality of electron-emitting devices, the characteristics of each electron-emitting device are obtained by multiplying the vertical axis of FIG. 4 by a constant (ratio of the number of emission points). Therefore, there is almost no gradation dependency of luminance variation. On the other hand, when the field multiplication factor (distance and shape between the emitter and the gate) of the electron-emitting device varies, the characteristics of each electron-emitting device are obtained by multiplying the horizontal axis of FIG. 4 by a constant (ratio of driving electric field). Because of the characteristics, the gradation dependence of the luminance variation is remarkably generated. Therefore, when the number of emission points and the electric field multiplication coefficient vary independently, the relationship of the luminance variation between the plurality of gradation values varies depending on the content of the variation in the number of emission points and the variation of the electric field multiplication factor. For this reason, in order to obtain an accurate correction value, it is necessary to measure the luminance variation for at least two gradation values. Since the luminance variation may have gradation dependency, a correction value for each display element is required for each gradation value. When the correction process is performed on the low gradation area, a correction value for each gradation value in the low gradation area is required.

For the above reasons, multivalue correction is necessary.
However, if a correction value for each display element is prepared for each of all gradation values, the data capacity becomes enormous and it is not realistic to realize it with hardware. Therefore, in this embodiment, some representative gradation values among all gradation values are selected, and correction values corresponding to the other gradation values are interpolated with correction values corresponding to the representative gradation values. It is generated using the correction value curve obtained in this way.
FIG. 5 shows the gradation dependency of the correction value, and is an example of correcting the gradation values of the display element A1 and the display element A3 so as to match the luminance of the display element A2.
In FIG. 5, the plot point of the display element A3 is an ideal value, and four correction values (U (Upper) point, M (Middle) point, L) corresponding to four representative gradation values below the gradation value m. (Lower) point, L ′ (Lower ′) point) is interpolated. However, in the example of FIG. 5, since the linear interpolation is performed between the correction values, the correction value curve includes an error (interpolation error) (the deviation occurs between the ideal value and the value obtained from the correction value curve). ). In order to reduce the error of the correction value curve, the number of representative gradation values must be large to some extent.

(Specific example for realizing multi-value correction)
A hardware configuration for realizing multi-value correction using the correction value curve as described above will be described with reference to FIG. FIG. 6 is a block diagram illustrating details of the luminance variation correction unit 203. FIG. 6 can be broadly divided into two processing systems: a correction data write / transfer processing system and a correction data read calculation processing system. Each processing system will be described in detail below.

Correction Data Writing / Transfer Processing System This processing system is provided to transfer correction data from a low-speed nonvolatile memory to a high-speed volatile memory at the start-up as a stage before performing luminance variation correction. Specifically, the system control unit 207 opens the system bus 209 to the memory write control unit 1000 at the time of startup. Then, when the preparation is completed, the system control unit 207 continuously reads out the correction data stored in the nonvolatile memory 208 to the memory write control unit 1000 to perform transfer. Such a transfer is generally called a DMA transfer.

  The memory write control unit 1000 stores the correction data transferred using the system bus 209 in an internal buffer and writes it in the volatile memory 1002 capable of high-speed operation. Note that the memory write control unit 1000 converts the format as necessary when writing the correction data into the volatile memory 1002. That is, in the present embodiment, the system control unit 207 and the memory write control unit 1000 constitute the transfer means of the present invention. The volatile memory 1002 is a memory (second storage unit) used as a work memory. The volatile memory 1002 is generally composed of DRAM, SRAM, or the like that is inexpensive and capable of high-speed operation, such as SDRAM or DDR2-SDRAM.

In the example of FIG. 5, since the correction values of four gradation values are transferred, the number of display elements is 1920 × 1080 × 3.
(= RGB) When one correction value is 8 bits, the transfer capacity is calculated as follows.
Transfer capacity = 1920 x 1080 x 8 bits x 3 (= RGB) x 4 = 199065600 bits (= 12441600 words)
Assuming that the system control unit 207 is a general 16-bit microcomputer or the like, the transfer time of the transfer capacity was calculated. Specifically, assuming that the bus clock of the system bus 209 is 25 MHz and 1 word data is transferred in a time of 7 cycles in one bus cycle of DMA transfer, the transfer time is calculated as follows.
Transfer time = 12441600 words x 40 ns x 7 = 2.18 sec
This transfer time that takes several seconds is a problem in this embodiment.

Correction Data Reading Operation Processing System This processing system is provided for reading correction data from the volatile memory 1002 and performing luminance variation correction on the input video signal. Specifically, in the multi-value correction calculation unit 1001 (correction means), the gradation value of the signal S3 is corrected using a correction value curve obtained by interpolating the correction value read from the volatile memory 1002, and the signal Output as S4.

The system control unit 207 instructs the multi-value correction calculation unit 1001 to start multi-value correction. The multi-value correction calculation unit 1001 reads four correction values corresponding to the four gradation values from the volatile memory 1002 in synchronization with the synchronization signal T2 from the timing control unit 206. Then, the selector 1003 selects two correction values necessary for multi-value correction from the read four correction values, and outputs them to the interpolation calculation unit 1004.

Here, the selection method by the selector 1003 will be described by taking the case of FIG. 5 as an example.
When the gradation value of the signal S3 (luminance data) is a gradation value between the U point and the M point, the selector 1003 selects the U point and the M point. If the tone value is between the tone values of the M point and the L point, the M point and the L point are selected. When the gradation value is between the gradation values of the L point and the L ′ point, the L point and the L ′ point are selected. When the gradation value is larger than the U point, the U point is selected. When the gradation value is smaller than the L ′ point, the L ′ point is selected.

The above-described method for reading four correction values from the volatile memory 1002 and selecting the optimum two correction values by the selector 1003 (four-value reading binary selection method) is wasteful in terms of the read band of the memory. . If it is possible to selectively read out the optimum two correction values from the volatile memory 1002, such a method (binary selection reading method) is preferable from the viewpoint of the reading band of the memory. In this case, the selector 1003 is not necessary.
In the following, a four-value reading / binary selection method will be described as an example.

A calculation method in the interpolation calculation unit 1004 will be specifically described. A case will be described in which the gradation value of the luminance data is din, and din is a gradation value between the gradation values of the M point and the L point. If the coordinates of the M point are (m_th, m_coef) and the coordinates of the L point are (l_th, l_coef), the correction value dout (correction value after interpolation) corresponding to the gradation value din can be calculated by the following equation. it can.
dout
= (1 / (m_th−l_th)) × ((m_coef−l_coef) × din + m_th × l_coef−l_th × m_coef)
= (1 / (m_th−l_th)) × (l_coef × (m_th−din) + m_coef × (din−l_th))
(However, l_th <din <m_th)
Then, the multiplier 1005 multiplies the luminance data by the correction value dout to obtain corrected luminance data (signal S4). Therefore, when the correction value is 1, the luminance data is output as it is. When the correction value is less than 1, the gradation value is corrected to lower (decrease the luminance), and when it is larger than 1, the gradation value is increased. Correction (increased brightness) will be performed. Even when the value of din is a gradation value between the gradation values of the U point and the M point, and the L point and the L ′ point, the correction value may be calculated by the same method. Further, when the gradation value of the luminance data is not a gradation value between gradation values corresponding to the correction values of U and L ′, the U point or L ′ point may be used as the correction value.

(Regarding processing at the time of starting the conventional image display device)
As described above, the transfer time that takes several seconds is a problem in this embodiment. The importance of this problem will be described with reference to FIGS.
FIG. 8 is a diagram showing a conventional startup sequence (change timings of various states). When the video signal supply device is activated at time t0 (when the power supply of the video signal supply device is turned on), the image display device is activated at time t1 after 0.6 sec (the power supply of the image display device is turned on). When the image display apparatus is activated, the system control unit 207 is reset and starts up according to the flowchart of FIG.

First, in S101 of FIG. 7, reset processing and initialization processing are performed. This process includes all the initialization processes such as the program loading by the boot process, the hardware reset process, and the PLL and the volatile memory 1002 for generating the internal clock, and sets the state of the image display device to the normal operation state. It is a series of processes for.
When the initialization completion is confirmed in S102, the drive signal S6 output from the drive conversion unit 205 is forcibly set to a black level (mute process) in S103. This is performed for the purpose of protection, for example, to prevent unintentional video from being output inadvertently.

In S104 (time t2), correction transfer / reflection processing is performed. Specifically, as described above, transfer of correction data is started in S105. In S106 (time t5), when N correction values (N = 4 in this embodiment) are transferred for each display element, these correction values (all correction data) are transferred in S107. The used correction process (N-value correction process) is enabled (executable). The correction process using all of the correction data is a process of converting the gradation value of the input video signal using the correction value curve obtained by interpolating N correction values as described above.
Next, when a display request signal from the video signal supply device that has become valid at time t3 is detected in S108, the mute process is turned off in S109. Specifically, the drive signal S6 is switched to a video signal that has been subjected to luminance variation correction using all of the correction data. The display request signal is a signal notifying that a video signal is stably input from the video signal supply device. Specifically, this is a signal that is valid when the video signal supply device stably outputs a synchronizing signal T1 and a video clock output (not shown) and a displayable video signal S1. At the same time as the display request signal becomes valid, the broadcast video signal may be displayed (broadcast display is possible) or may be broadcasted thereafter.
Then, the drive power source 215 is activated (driven) in S110, and the high voltage power source 216 is activated in S108, whereby video display on the display panel (display of video based on a video signal subjected to luminance variation correction) is started. The

As described above, in the conventional method, it takes about 3 seconds from starting the video supply device to displaying the video (startup time) (FIG. 8). This time may further increase as the gradation of the display panel 200 improves and the definition becomes higher. For example, in order to improve the gradation performance of a dark part (low gradation region), correction values corresponding to more gradation values are required in the low gradation region, so that the startup time becomes long. Specifically, when the correction value is increased from 4 to 6, the startup time is 1.5 times 4.5 seconds. In addition, due to ultra-high definition corresponding to digital cinema such as 4K2K, the data amount increases four times as compared with HD, so the startup time increases to 12 seconds at a stretch.

  In this embodiment, after the image display device is activated, when a part of the correction data is written into the volatile memory 1002, the multi-value correction calculation unit 1001 uses the partial data for provisional correction. The processing is started and video display is started. Then, after the remaining data of the correction data is written in the volatile memory 1002, the correction process by the multi-value correction calculation unit 1001 is switched to the correction process using the entire correction data. Thereby, an image with reduced luminance variation is displayed in a short time. This will be described in detail below.

(About processing at the time of starting the image display apparatus according to the present embodiment)
A specific example of processing at the time of starting the image display apparatus according to the first embodiment will be described with reference to FIGS. 9 and 10.
FIG. 9 corresponds to the correction transfer / reflection process in S104 of FIG. 7, and is a flowchart showing the stepwise transfer of correction data representing the features of this embodiment and the correction reflection method (the process flow of the system control unit 207). Is a flowchart). FIG. 10 is a timing chart showing an example of a startup sequence according to this embodiment. In this embodiment, the system control unit 207 and a correction value output control unit 2000 described later constitute the control means of the present invention.

Next to S103 in FIG. 7, at time t2 in FIG. 10, the system control unit 207 first transfers among N correction values to be transferred from now on (n is an integer of 1 or more and less than N; this In the embodiment, two first correction values are selected (S201). Hereinafter, the n first correction values (part of correction data) are referred to as first correction data. In this embodiment, two correction values (point U and point L ′) are selected so as to reduce the average interpolation error as much as possible in the entire area below the gradation value m in FIG. These correction values are stored in the nonvolatile memory 208 as preset values of the system control unit 207 and loaded in S201. This selection method is merely an example, and combinations other than these two points may be selected.

In step S <b> 202, the selected first correction value stored in the nonvolatile memory 208 is transferred to the volatile memory 1002.
When the transfer of the first correction data is completed in S203 (time t5), the first correction value (binary) is forcibly selected by the selector 1003 in S204, and the correction process using the first correction value is performed. (Temporary correction processing: first correction processing) is enabled. The provisional correction process is a process of converting a gradation value of an input video signal using a correction value curve obtained by interpolating n correction values (first correction values) (n value correction process). ).
Next, when a display request signal that is valid at time t3 is detected in S205, the drive signal S6 is switched to a video signal that has undergone provisional correction processing in S206 (mute processing off). Then, the drive power supply is turned on in S207 and the high voltage power supply is turned on in S208, whereby video display on the display panel 200 is started (specifically, time t5 is later than time t4 at which broadcast display is possible). Therefore, the broadcast display is started).

Next, in S209 (time t5), the remaining correction values (second correction values; M point and L point in this embodiment) stored in the nonvolatile memory 208 are transferred to the volatile memory 1002. . Hereinafter, the remaining correction values are referred to as second correction data.
When the transfer of the second correction data is completed in S210 (time t6), the correction process (second correction process) using all of the correction data is validated in S211. In other words, the correction process is switched from the first correction process to the second correction process. As a result, the correction value curve is switched from the first correction value curve shown in FIG. 5 to the second correction value curve. Specifically, the correction value selection method in the selector 1003 is switched to a method of selecting two points with reference to the luminance data described above (four-value reading binary selection method).

  As described above, in this embodiment, when a part of the correction data is written, the provisional correction process and the control to start the video display are performed, so that the video with the reduced luminance variation can be shortened for a short time. Can be displayed. Specifically, half of the correction data is transferred, and provisional correction processing and control to start video display are performed, thereby shortening the time until video display by half in the same system configuration as before. can do. In the first correction process, the interpolation error of the correction value curve is larger than that in the second correction process. However, since the correction process is switched to the second correction process in a relatively short time, there is a problem with the image quality of appearance in the video. Almost does not occur.

(Regarding the issue of memory access during provisional correction processing)
Here, a problem of memory access at the time of provisional correction processing will be described. In the period from time t5 to time t6 in FIG. 10, both the writing of the second correction data to the volatile memory 1002 and the reading of the first correction data from the volatile memory 1002 are performed. For this reason, it is necessary to allocate a memory bandwidth that can process the first correction data (binary) and the second correction data (binary) in a time-sharing manner to the volatile memory 1002.

In the case of the four-value reading binary selection method, a memory band is allocated so that the first correction data and the second correction data (four values) can be read after time t6. Therefore, the necessary bandwidth from time t5 to time t6 does not exceed the necessary bandwidth after time t6.
However, in the case of the binary selective reading method, only binary reading selected from four values is performed after time t6. Therefore, the necessary band from time t5 to time t6 becomes larger than the necessary band after time t6. There is no problem if the memory bandwidth is allocated in accordance with the necessary bandwidth from time t5 to time t6. However, since this period is a relatively short period (several seconds) that occurs only once when the power is turned on, allocating a large memory bandwidth for this period causes an increase in cost and is not appropriate.

  On the other hand, the video has a vertical blanking period (a period from displaying the last line of a certain frame to displaying the first line of the next frame). This vertical blanking period is a period during which correction data reading is suspended. Therefore, a method of writing the second correction data (binary) using this vertical blanking period is also conceivable. If the transfer time in this case is roughly estimated, in the example of FIG. 10, the transfer time of the second correction data is 1.1 seconds. Therefore, when 4% of the processing time for one frame is the vertical blanking period, the second correction data This takes 1.1 seconds / 4% = 28.72 seconds. Performing provisional correction processing for such a long time is problematic from the viewpoint of image quality.

  Therefore, in this embodiment, during the period from when the first correction data is written to the volatile memory 1002 to when the second correction data is written to the non-volatile memory 1002, provisional for a part of the frames of the input video signal. A typical correction process is omitted. Thereby, the non-reading time during which the multi-value correction calculation unit 1001 does not access the nonvolatile memory 1002 is generated. Then, such a non-reading time is assigned to a process in which the transfer unit writes the second correction data to the volatile memory 1002.

This will be specifically described below with reference to FIG. FIG. 1 shows an example of a start-up sequence that is characteristic in the present embodiment. The start-up sequence according to the present embodiment can be applied particularly suitably in the case of the binary selective read system. FIG. 1 shows an example in which a video signal having a frame rate of 120 Hz is input from the video supply device side.
A characteristic feature of this embodiment is that a black screen (mute) is displayed on the display panel instead of the partial frame (correction-off frame) from which the provisional correction process is omitted. Specifically, in a period in which the writing of the second correction data and the reading of the second correction data overlap, the frame rate of the video is halved by black insertion. That is, in the example of FIG. 1, during the period from time t5 to time t6, a black screen is displayed at a frame rate of 60 Hz, and the frame rate of the video is changed from 120 Hz to 60 Hz (black insertion 60 Hz drive). At this time, a binary correction process using the first correction data is performed as the correction process. After time t6, black insertion is canceled and the video frame rate is returned to 120 Hz (120 Hz drive). At this time, four-value correction processing is performed as correction processing.

  In this embodiment, the correction value output control unit 2000 generates a signal for identifying a black insertion period (a period in which provisional correction processing is omitted) as a write permission signal based on the vertical synchronization signal of the video signal. Based on the write permission signal, the multivalue correction calculation unit 1001 stops reading correction data from the volatile memory 1002 during the black insertion period, and sets a correction value after interpolation by the correction value selector 2001. Switch to correction value (0.0). Further, the memory write control unit 1000 controls the system control unit 207 to perform the above-described DMA transfer only during the black insertion period based on the write permission signal. On the other hand, during a period other than the black insertion period, correction data is read from the volatile memory 1002, and the correction value selector 2001 selects a correction value after interpolation. The system control unit 207 is controlled not to perform DMA transfer.

  By performing the control as described above, the transfer time of the second correction data can be sufficiently shortened to 1.1 seconds × 2 = 2.2 seconds in the example of FIG. Thereby, it is possible to reduce the influence on the image quality due to the provisional correction processing.

The example of FIG. 1 shows a case where video signal frames and black screens are displayed alternately (that is, when the ratio of the number of video signal frames to black screens is 1: 1). The number of signal frames: the number of black screens may be 2: 1, 3: 1, 4: 1,. In addition, when the video signal is composed of an original frame and an interpolation frame that is generated using the original frame and interpolates between the original frames, the image quality of the interpolation frame is lower than the image quality of the original frame. For this reason, it is preferable from the viewpoint of image quality to omit provisional correction processing for the interpolated frame instead of the original frame. For example, the video supply device may output a frame identification signal that distinguishes an original frame and an interpolation frame. Then, the correction value output control unit 2000 may generate a write permission signal with the interpolation frame period as the black insertion period in accordance with the vertical synchronization signal and the frame identification signal.

In the case where the display panel 200 is an impulse display device, in the period from time t5 to time t6, the display luminance (time average luminance) that is time-averaged from the period after time t6 becomes darker for the same video. End up. Specifically, in the case of the example of FIG. 1, since the black screen and the video frame are alternately displayed, the time average luminance is ½ compared to the case where black insertion is not performed. Therefore, when the video frame rate is switched from 60 Hz to 120 Hz, the luminance changes (the time average luminance is doubled), which may give the viewer a sense of incongruity.
Therefore, in this embodiment, a gain multiplication circuit (not shown; reduction means) for reducing the luminance of the video signal input before the luminance variation correcting unit 203 in FIG. 2 is prepared. Then, when the system control unit 207 starts the second correction process, the luminance of the input video signal becomes equal to the time average luminance during the period from time t5 to time t6. Set the reduction rate. Thereafter, the luminance of the input video signal is increased stepwise until the reduction rate becomes zero. In the case of reducing the luminance of the video signal by multiplying the gain value by the gain multiplication circuit, for example, the gain value is set to 1 during the period from time t5 to time t6 so that the change in luminance is not visible after time t6. The gain value may be controlled so as to gradually approach from 0.5 to 1. Note that the luminance control described above is merely an example, and any control may be used as long as the viewer does not feel uncomfortable due to a change in luminance. Also, the reduction rate is determined in advance so as to compensate for the difference in time-average luminance of the video displayed before and after switching according to the change in frame rate (frame rate before and after switching), regardless of the input video signal. It may be decided.

  In the case where the display panel 200 is an impulse type display device, flicker may be noticeable in the period from time t5 to time t6. Therefore, in the case where the display panel 200 is an impulse type display device, it is only necessary to reduce the luminance in the period from the time t5 to the time t6 (for example, the gain value is about 0.5) and make the flicker inconspicuous. Then, after time t6, the gain value may be controlled to gradually approach 1 from 0.25 so that the luminance change is not visible.

  As described above, according to the present embodiment, when a part of the correction data is written, provisional correction processing and video display control are performed to shorten the video with reduced luminance variation. Can be displayed in time. In addition, the provisional correction process for some frames of the video signal is omitted, and the period is assigned to the process of writing the remaining data of the correction data to the work memory, thereby increasing the processing bandwidth of the work memory. Can be obtained without inviting.

<Example 2>
In the first embodiment, the example in which the video frame rate is reduced to ½ by black insertion has been described. In Embodiment 2 of the present invention, a method for obtaining the same effect as Embodiment 1 without reducing the video frame rate will be described with reference to FIG.
As shown in FIG. 11, in this embodiment, video is displayed at a frame rate of 120 Hz in all periods after time t5. However, in a period in which writing of transfer processing and reading of correction processing overlap from time t5 to time t6, a video in which binary correction on / off is switched in units of frames is displayed instead of video mute (provisional). 120 Hz drive).

  In this embodiment, the correction value output control unit 2000 generates a signal for identifying a period (correction off period) in which the provisional correction process is omitted based on the vertical synchronization signal as a write permission signal. Then, by using this write permission signal, the same effect as that of the first embodiment is controlled by controlling the writing of the correction data to the volatile memory 1002 and the reading of the correction data from the volatile memory 1002 as in the first embodiment. Is obtained.

  In addition, there are two problems to be considered for switching on / off of provisional correction processing in units of frames in the period from time t5 to time t6. The first is a reduction in correction performance. Second, there is a sense of discomfort in the display due to a change in luminance caused by turning on / off the temporary correction process.

The first problem will be described. When switching the temporary correction process positive on / off, the correction error is averaged in the time direction, so that the correction error increases as compared with the case where the temporary correction process is continuously performed. Such an increase in the correction error has little variation in luminance of the display panel 200 and when the length of the period from the time t5 to the time t6 is relatively short as 2.2 seconds as in this embodiment, I don't know how it looks. However, when the luminance variation of the display panel 200 is large, it is preferable to reduce the correction error (make it inconspicuous). Specifically, it is preferable that the duty ratio during the on / off period of the temporary correction process can be changed. The duty ratio is a ratio of the number of frames for which provisional correction processing is performed (correction on frame) and frames to be omitted (correction off frame). For example, the correction error can be made inconspicuous by setting the correction on frame: correction off frame to 3: 1. The duty ratio (corrected on frame: corrected off frame) is not limited to 3: 1, but may be 2: 1, 4: 1, 5: 1, or the like.
Specifically, such a function can be realized by the correction value output control unit 2000 changing the write permission signal according to the duty ratio. However, as the number of correction on-frames with respect to the correction off-frame increases, the correction error becomes less conspicuous, but the length of the period from time t5 to time t6 becomes longer. For example, if the correction on frame: correction off frame is 3: 1, the length of the period from time t5 to time t6 is doubled (4.4 seconds) compared to 1: 1. That is, the duty ratio and the length of the period from time t5 to time t6 are in a trade-off relationship, and it is preferable to determine the duty ratio so that the influence on the image quality by both is minimized.

The second problem will be described. In luminance variation correction (correction processing using a part of correction data or correction processing using all correction data), the luminance value is converted to a target luminance value (target value) for each pixel. For this reason, when the same image is displayed, the average luminance differs between when the luminance variation correction is on and when it is off. This will be described in more detail with reference to FIG. FIG. 12 is a diagram illustrating an example of the luminance variation distribution and the target luminance value before correction of the display panel 200. From the luminance variation distribution before correction, for example, a luminance value (73% of the average luminance in the example of FIG. 12) at a position lower than the average luminance by 3σ (σ is a standard deviation) is set as the target luminance value. Of course, these numerical values are merely examples, and may be set as appropriate in accordance with the luminance unevenness specification of the image display device and the luminance variation distribution before correction. A range indicated by a thick line (arrow) in FIG. 12 indicates a correction range. In other words, in this embodiment, pixels having a luminance value lower than the target luminance value are not subjected to correction of luminance variation (such pixels are left as corrections). Therefore, in the example of FIG. 12, the average luminance after performing the luminance variation correction is approximately 73% of the average luminance before performing the luminance variation correction.
Therefore, in this embodiment, the overall brightness of the corrected off frame is set so that the average brightness of the corrected off frame becomes equal to the average brightness when the brightness variation correction is performed on the same image as the image of the corrected off frame. Is reduced by a predetermined ratio (73% before correction). Thereby, it is possible to prevent display discomfort due to a change in luminance due to the on / off of the temporary correction processing.
Specifically, the gain value for luminance control described in the first embodiment is 1. In a period during which the provisional correction processing is omitted, the multi-value correction calculation unit 1001 stops reading the first correction data from the volatile memory 1002 and the correction value selector 2001 sets the correction value after interpolation. Switch to the setting correction value (0.73). Thereby, the above function can be realized.

By performing the control as described above, it is possible to obtain the same effect as in the first embodiment without reducing the frame rate.
In this embodiment, the overall brightness of the corrected off frame is set so that the average brightness of the corrected off frame is equal to the average brightness when the brightness variation correction is performed on the same image as the image of the corrected off frame. The configuration is reduced to the above. However, such a control may not be performed, and the overall luminance may be reduced to such an extent that luminance variations are not noticeable. Even with such a configuration, an effect equivalent to that of the first embodiment can be obtained.

200 Display Panel 207 System Control Unit 208 Non-Volatile Memory 1000 Memory Write Control Unit 1001 Multilevel Correction Operation Unit 1002 Volatile Memory 2000 Correction Value Output Control Unit

Claims (8)

A display panel having a plurality of display elements arranged in a matrix;
First storage means for storing correction data used in correction processing to reduce luminance variation among the plurality of display elements;
Second storage means used as a work memory;
Transfer means for transferring the correction data from the first storage means to the second storage means;
Correction means for reading correction data from the second storage means and performing the correction processing on the input video signal;
Control means;
Have
The control means includes
At the time when a part of the correction data is written to the second storage unit by the transfer unit, the correction unit starts a provisional correction process using the part of the data, and the display panel Video display on
After the remaining data of the correction data is written to the second storage unit by the transfer unit, the correction process by the correction unit is switched to a correction process using all of the correction data,
The provisional correction for some frames of the input video signal in a period from when the partial data is written to the second storage means to when the remaining data is written to the second storage means By omitting the process, the correction unit generates a non-read time during which the second storage unit is not accessed,
An image display apparatus, wherein the non-reading time is allocated to a process in which the transfer unit writes the remaining data in the second storage unit. The image display apparatus according to claim 1, wherein the control unit reduces the luminance of the partial frames from which the provisional correction process is omitted by a predetermined ratio as a whole. The image display apparatus according to claim 1, wherein the control unit displays a black screen on the display panel in place of the partial frame from which the provisional correction process is omitted. It further has a reduction means for reducing the luminance of the input video signal,
When the correction process using all of the correction data is started, the control unit stores the time average luminance of the video displayed thereafter and the partial data in the second storage. The remaining data is input at a preset reduction rate so as to compensate for the difference from the time average luminance of the video displayed in the period from when the remaining data is written to the second storage means. Reduce the brightness of the video signal,
The image display device according to claim 1, wherein the reduction rate is set to increase the luminance of the input video signal in a stepwise manner. The predetermined ratio is set so that an average luminance of the some frames is equal to an average luminance when the correction process is performed on the same image as the image of the frame. 2. The image display device according to 2. The input video signal is composed of an original frame and an interpolation frame generated by using the original frame and interpolating between the original frames.
The image display apparatus according to claim 1, wherein the control unit omits the provisional correction process for the interpolation frame. The image display apparatus according to claim 1, wherein the display element is an electron-emitting device. A display panel having a plurality of display elements arranged in a matrix;
First storage means for storing correction data used in correction processing to reduce luminance variation among the plurality of display elements;
Second storage means used as a work memory;
Transfer means for transferring the correction data from the first storage means to the second storage means;
Correction means for reading correction data from the second storage means and performing the correction processing on the input video signal;
A method for controlling an image display device comprising:
At the time when a part of the correction data is written to the second storage unit by the transfer unit, the correction unit starts a provisional correction process using the part of the data, and the display panel Starting video display on
After the remaining data of the correction data is written to the second storage unit by the transfer unit, the correction process by the correction unit is switched to a correction process using all of the correction data;
The provisional correction for some frames of the input video signal in a period from when the partial data is written to the second storage means to when the remaining data is written to the second storage means By omitting the process, the correction unit generates a non-reading time during which the second storage unit is not accessed, and the transfer unit writes the remaining data into the second storage unit. Assigning steps,
A control method for an image display device, comprising:

Images