JP2013037374A - Image display device and method of optimizing overdrive coefficient in image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable determination of an overdrive coefficient by accurately estimating the temperature of a display panel.SOLUTION: An image display device comprises: an overdrive driving section equipped with a lookup table that, on the basis of an overdrive coefficient determined by a current frame video and an immediately preceding frame video, performs overdrive driving of a display panel; a temperature detection section that detects the temperature of the display panel; a storage section in which a plurality of overdrive coefficients appropriate for the detected temperature are stored; a time monitoring section that monitors an elapsed operation time of the display panel at start-up or recovery from an idle state; and a control section that, using elapsed operation time information acquired from the time monitoring section, selects an optimum overdrive coefficient from the plurality of overdrive coefficients appropriate for temperature information acquired from the temperature detection section, and sets the optimum coefficient to the lookup table.

Description

  In particular, the present invention relates to an image display device suitable for use in LCD moving image display that performs overdrive driving, and an overdrive coefficient optimization method in the image display device.

In recent years, flat panel displays such as liquid crystal (LCD) displays have become widespread as image display devices.
In addition, with the speeding up of PCs, the number of cases of handling moving image display on an LCD has increased. Further, along with the increase in the size of LCD panels and the improvement in image quality, they have become widespread as television applications in general households, and there is an increasing demand for moving image display quality of LCD panels in the distribution market.

By the way, the above-mentioned LCD panel displays an image by changing the transmittance of each cell by changing the electric field applied to each cell (pixel) constituting the LCD panel. At this time, since the transmittance of the LCD cell changes relatively slowly, there is a problem with response speed such that when a moving image is displayed, a part of the image of the immediately preceding frame overlaps with the image of the current frame and appears to be blurred. .
In order to improve the response speed described above, a general LCD panel employs a method of performing overdrive driving by applying a voltage higher than the normal voltage. For this reason, the input data and the input data of the previous frame are A look-up table for obtaining output data from is used.

However, although the response speed of the LCD panel is improved by the overdrive driving described above, the response speed is highly temperature dependent. When the overdrive coefficient written in the look-up table is fixed, the temperature change occurs. Does not achieve the optimal overdrive drive, and the blurred edge of the screen is emphasized.
For this reason, the overdrive coefficient is adjusted according to changes in the ambient temperature, or a plurality of lookup tables for each temperature are provided, and the optimum lookup table is selected and switched to perform overdrive driving. Many LCD displays have been proposed in the past (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3).

Japanese Patent Laying-Open No. 2003-241721 (paragraph “0022”, FIGS. 1 and 2) JP 2005-114955 A (paragraph “0021”, FIG. 4) Japanese Patent Laying-Open No. 2005-272882 (paragraph “0019”)

According to the techniques disclosed in Patent Documents 1 to 3 described above, an optimal overdrive coefficient can be obtained according to the ambient temperature of the LCD panel, and thus improved image quality can be obtained.
However, there are various factors for the temperature change of the LCD panel, such as when the LCD monitor is rotated from the horizontal position to the vertical position, or when the LCD monitor returns from the hibernation state, and the temperature provided in the vicinity of the LCD panel. Since the temperature measured by the sensor does not necessarily become the temperature of the LCD panel, how to accurately predict the temperature of the LCD panel and determine the overdrive coefficient has become the most important design matter.

  The present invention has been made based on the above various circumstances, and provides an image display apparatus and an overdrive coefficient optimization method for an image display apparatus that accurately predict the temperature of a display panel and determine an overdrive coefficient. The task is to do.

  In order to solve the above-described problems, an image display device according to the present invention has an overdrive drive including a look-up table for performing overdrive drive of a display panel based on an overdrive coefficient determined by a current frame image and a previous frame image. , A temperature detection unit for detecting the temperature of the display panel, a storage unit for storing a plurality of overdrive coefficients suitable for the detected temperature, and an operation of the display panel when the display panel is restored from a start or hibernation state A time monitoring unit that monitors the elapsed time, and a storage unit that uses the operation elapsed time information acquired from the time monitoring unit among the plurality of overdrive coefficients suitable for the temperature information acquired from the temperature detection unit. A control unit that selects a stored overdrive coefficient and sets the stored overdrive coefficient in the lookup table. And features.

  The present invention also provides an optimization method for an overdrive coefficient in an image display device including a look-up table for performing overdrive driving of a display panel based on an overdrive coefficient determined by a current frame image and a previous frame image. Detecting the temperature of the display panel, monitoring the operation elapsed time of the display panel when the image display device is returned from a start-up or hibernation state, the detected temperature information, and the monitoring Using the obtained operation elapsed time information, selecting an optimum overdrive coefficient from a plurality of overdrive coefficients suitable for the temperature stored in advance in a storage unit, and setting the lookup table, Display based on the overdrive factor set in the lookup table And having a step of performing overdrive panel, the.

  According to the present invention, the overdrive coefficient can be determined by accurately predicting the temperature of the display panel.

1 is a block diagram showing an internal configuration of an image display apparatus according to Embodiment 1 of the present invention. It is a figure which shows an example of the data structure of the look-up table used in Embodiment 1 of this invention. It is a figure quoted in order to explain the response time of the overdrive drive of the image display device in Embodiment 1 of the present invention. 5 is a flowchart cited for explaining the operation of the image display apparatus according to the first embodiment of the present invention. 3 is a graph showing temperature characteristics of the display panel 12 in Embodiment 1 of the present invention. FIG. 5 is a block diagram cited for explaining an application example in the first embodiment of the present invention. FIG. 5 is a block diagram cited for explaining an application example in the first embodiment of the present invention. It is a block diagram which shows the internal structure of the image display apparatus concerning Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing an internal configuration of an image display apparatus according to Embodiment 1 of the present invention.
The image display apparatus according to the first embodiment of the present invention includes a signal processing unit 10, an overdrive drive unit 11, a display panel 12, a storage unit 13, a temperature detection unit 14, a time monitoring unit 15, and a control. Part 16.

The signal processing unit 10 executes processing according to the input video signal in accordance with the display format of the display panel 12 and outputs the processed signal to the overdrive driving unit 11. The overdrive drive unit 11 performs overdrive driving of the display panel 12 based on an overdrive coefficient determined by the current frame image and the immediately preceding frame image. The overdrive drive unit 11 also includes a lookup table 111 in which an overdrive coefficient is set.
Here, the display panel 12 is an LCD panel that displays an image by changing the transmittance of each cell by changing the electric field applied to each cell (pixel).

On the other hand, the storage unit 13 stores a plurality of overdrive coefficients suitable for the temperature detected by the temperature detection unit 14. The temperature detection unit 14 detects the temperature near the display panel 12 using a temperature sensor or the like and outputs the detected temperature to the control unit 16. Furthermore, the time monitoring unit 15 monitors the operation elapsed time of the display panel 12 when returning from the PC activation or hibernation state, and outputs it to the control unit 16.
The control unit 16 uses the temperature information acquired from the temperature detection unit 14 and the operation elapsed time information acquired from the time monitoring unit 15 to select an optimum overdrive coefficient from among the overdrive coefficients stored in the storage unit 13. Is selected and output to the overdrive drive unit 11 and set in the built-in lookup table 111. The control unit 16 is specifically composed of a microcomputer or the like, and realizes the above-described functions by sequentially reading and executing a program recorded in a built-in ROM.

In the above configuration, the video signal 1a output from the PC is input to the signal processing unit 10 in the image display device, where processing such as color conversion and image enlargement is performed. The video signal output as a processing result is input to the overdrive drive unit 11.
The overdrive drive unit 11 performs reference using the look-up table 111 based on the video signal output to the display panel 12 in the immediately previous frame and the video signal of the current frame, thereby determining the video signal. A video signal is output to the display panel 12.

The lookup table 111 has, for example, the data structure shown in FIG. 2, and can arbitrarily set a video signal to be output this time from the immediately preceding frame (video one frame before) and the current frame (current video). It is possible. Here, by setting the overdrive coefficient so that a video signal emphasized over the video signal of the current frame is output with respect to a change in the video signal whose response speed of the display panel 12 is slow, the display panel 12 Then, the overdrive driving shown in FIG. This improves the response speed.
FIG. 3 is a diagram cited for explaining the response time of overdrive driving of the image display device, where (a) is a video signal from a PC, and (b) is a video when no overdrive driving is performed. The response time for the signal, (c) shows the response time for the video signal when overdrive driving is performed.

FIG. 4 is a flowchart cited for explaining the operation of the control unit 16. Hereinafter, the overdrive optimization process by the control unit 16 will be described in detail with reference to the flowchart shown in FIG.
First, the control unit 16 acquires temperature information from the temperature detection unit 14 provided in the image display device (step S41). Subsequently, the acquired temperature information is compared with the previously measured temperature information, and the presence or absence of a change is determined (step S42). Here, when it is determined that there is a change, the control unit 16 refers to the lookup table 111 in the overdrive drive unit 11 and determines the reference destination of the optimum overdrive coefficient (step S43). If there is no change, the overdrive optimization process is terminated.

Further, the control unit 16 determines whether or not the reference overdrive coefficient has already been set in the lookup table 111 (step S44), and if not set, based on the temperature information acquired by the temperature detection unit 14. The temperature of the display panel 12 is predicted, and an appropriate overdrive coefficient is selected and read from the storage unit 13 holding a plurality of overdrive coefficients corresponding to the temperature (step S45). Then, the read overdrive coefficient is set in the lookup table 111 in the overdrive drive unit 11 to switch to the overdrive coefficient suitable for the temperature, and the overdrive optimization process is ended (step S46). .
If it is determined in step S44 that the reference overdrive coefficient has already been set, the overdrive optimization process described above ends.

The above description is a basic configuration for well-known overdrive optimization. However, as described above, the response speed of the display panel 12 has a large temperature dependency, and the temperature change of the display panel 12 is caused by the display panel 12. It changes with the operation time of.
Specifically, as shown in the temperature characteristics of the display panel 12 in FIG. 5, the temperature of the display panel 12 rapidly increases immediately after startup (power on), and rapidly decreases after the power is turned off. Further, when the display panel 12 is in use, the same temperature change occurs when the PC to which the display panel 12 is connected enters the hibernation state (power off) and returns from the hibernation state (restart). .

Therefore, in order to grasp the temperature of the display panel 12, it is desirable to provide the temperature detection unit 14 such as a temperature sensor directly on the display panel 12, but there is a technical problem in terms of manufacturing and high cost. Therefore, in many cases, the temperature detection unit 14 is provided in a location near the display panel 12 such as a control board, and the temperature of the display panel 12 must be predicted from the indirectly measured temperature information. .
However, since the temperature is indirectly measured, the actual temperature of the display panel 12 does not necessarily match, and the temperature information for optimizing the overdrive coefficient is not accurate. As shown in FIG. 5, the temperature rise when the power is turned on or the PC returns from the hibernation state depends on the operation elapsed time such as the power off or the PC hibernation state. Means are needed.

In the first embodiment of the present invention, a time monitoring unit 15 is provided as means for monitoring the operation elapsed time information, and the control unit 16 performs power on / off and PC hibernation / return. In addition, those times are acquired from the time monitoring unit 15. Thus, when selecting the overdrive coefficient, the control unit 16 predicts the temperature of the display panel 12 from the temperature information acquired from the temperature detection unit 14 and the time information acquired from the time monitoring unit 15. Is possible.
Specifically, in step S44 of the flowchart shown in FIG. 4, the control unit 16 obtains, from the time monitoring unit 15, operation elapsed time information when returning from the startup or hibernation state in addition to the temperature information. In the processing of S45 and S46, the control unit 16 uses the temperature information and the elapsed time information to select an optimum overdrive coefficient from among a plurality of overdrive coefficients stored in the storage unit 13, and performs lookup. Set in table 111.

6 and 7 show application examples of the image display apparatus according to Embodiment 1 of the present invention. Specifically, as shown in FIG. 6, the configuration shown in FIG. 1 is further provided with an outside air temperature detection unit 51 including a temperature sensor or the like for measuring the outside air temperature outside the image display device. By adding, the control unit 16 predicts the accurate temperature of the display panel 12 from the difference between the temperature (outside air temperature) in the usage environment of the image display device and the temperature on the control board by the temperature detection unit 14. Since the temperature prediction accuracy of the display panel 12 is improved, the optimum overdrive coefficient can be obtained and combined with the operation elapsed time information by the time monitoring unit 15 at the time of power activation. In addition, high-quality moving image display can be realized even when returning from a PC sleep state.
In FIG. 6, the configuration other than the outside air temperature detection unit 51 is the same as the configuration illustrated in FIG. 1, and thus description thereof is omitted to avoid duplication.

FIG. 7 is a diagram illustrating a configuration of an image display device in which a rotation direction detection unit 61 is added to the image display device illustrated in FIG. 1.
As described above, the temperature change of the display panel 12 depends on the operation elapsed time, but the temperature change further depends on the use state of the image display apparatus. For example, in an image display apparatus that can be used by rotating the display panel 12 around a mechanical component as a fulcrum and switching from a vertical position to a horizontal position or vice versa, the image display apparatus can be used from a horizontal position to a vertical position. When changing the state, the display panel 12 needs to be rotated from the horizontal direction to the vertical direction. In this case, since the temperature of the display panel 12 changes the positional relationship with the heat-generating component, the display panel 12 is used horizontally. The temperature characteristics are different from that of the case. Further, the temperature detected by the temperature detection unit 14 also has different measurement results for the same reason, and thus correction is necessary for the temperature information output from the temperature detection unit 14.

In the application example shown in FIG. 7, in addition to the configuration shown in FIG. 1, in order to detect the rotation direction of the image display device (display panel 12) described above, a rotation direction detection unit 61 composed of a micro switch or the like is added. Yes. For this reason, the control unit 16 can always acquire the rotation state of the image display device from the rotation direction detection unit 61. When selecting the overdrive coefficient, the control unit 16 uses the temperature information acquired from the temperature detection unit 14, the time information acquired from the time monitoring unit 15, and the rotation state information of the image display device 12. It is possible to predict the temperature of the display panel 12 more accurately, and the temperature of the display panel 12 can be further predicted by adding the outside air temperature information acquired from the outside air temperature detecting unit 51 of the application example shown in FIG. By selecting an overdrive coefficient that is improved in accuracy and most suitable for the usage state of the image display device, high-quality moving image display can be realized.
In FIG. 7, the configuration other than the rotation direction detection unit 61 is the same as the configuration illustrated in FIG. 1, and thus description thereof is omitted to avoid duplication.

  According to the first embodiment of the present invention described above, various temperature change factors are grasped with respect to the response speed of the display panel 12 having temperature dependence, and the overdrive is optimized by correcting the temperature information. By improving the response speed of the display panel 12, it is possible to provide an image display device equipped with an overdrive function for stably displaying high-quality moving images to the user.

Embodiment 2. FIG.
FIG. 8 is a block diagram showing an internal configuration of the image display apparatus according to Embodiment 2 of the present invention.
8, reference numerals 70 to 75 denote the signal processing unit 10, the overdrive drive unit 11, the display panel 12, the storage unit 13, the temperature detection unit 14, and the time monitoring unit 15 of the first embodiment shown in FIG. Therefore, the configuration and operation description here are omitted. According to the second embodiment of the present invention, a test pattern generation unit 77 and a response speed measurement unit 78 are further added to the above configuration, and the control unit 76 has a test pattern generation unit 77 and a response speed measurement unit 78. Are used to calculate and optimize the overdrive coefficient. Details will be described below.

  The control unit 76 can display a video signal on the display panel 72 using the test pattern generation unit 77, and here, as an example, can generate a video signal of 0 to 255 gradations. And The response speed measurement unit 78 is provided on the front surface of the display panel 72 and can convert the measured luminance value into a voltage value and output it to the control unit 76. Thus, the control unit 76 can take in the luminance level information from the voltage value.

When the control unit 76 enters a mode for measuring the response speed of the display panel 72, the test pattern generation unit 77 can output a video signal to the display panel 72 even when there is no input video signal. it can. In order to measure the response speed of the display panel 72, the control unit 76 instructs the test pattern generation unit 77 to output a 0-gradation video signal first, and uses the response speed measurement unit 78 to change the luminance level. Start sampling and import. Subsequently, a video signal of one gradation is output from the test pattern generation unit 77, and the luminance level is sampled and captured by the response speed measurement unit 78.
Next, the control unit 76 changes the overdrive coefficient 0-1 of the lookup table 711 to sample the luminance level at the time of gradation change, and repeats this operation until the luminance level stabilization time is shortened. The coefficient when the stabilization time is shortened is the optimum coefficient when the 0-1 gradation changes.

Similarly, the above operation is repeatedly measured up to 0-2, 0-3,..., 0-255 gradation, and the overdrive coefficient is calculated, so that the image of the previous frame is 0, and the image of the current frame is 0. The overdrive coefficient can be optimized with 255 combinations.
Similarly, the temperature information acquired from the temperature detection unit 74 is calculated by calculating an optimal all overdrive coefficient when the image of the current frame is changed from 0 to 255 while changing the image of the previous frame from 1 to 255. And the optimal overdrive coefficient are stored in the storage unit 73 based on the time information acquired from the time monitoring unit 75. Note that when the video of the previous frame and the current frame are the same, it is not necessary to perform overdrive driving, and therefore measurement is omitted.

  According to the second embodiment of the present invention described above, even after the image display device is manufactured, the response speed of the display panel 72 can be increased by the image display device itself without generating an expensive measuring instrument, service, and maintenance costs. By optimizing the overdrive coefficient, it is possible to achieve overdrive drive suitable for the characteristics of the display panel 72, ambient temperature, and usage environment, and to display high-quality video over the long term to the user. An image display device equipped with a drive function can be provided.

  As described above, the present invention includes temperature detection means (temperature detection units 14, 74) such as temperature sensors provided inside and outside, and means (time monitoring units 15, 75) for monitoring the operation elapsed time of the display panel. It is possible to optimize the temperature of the display panel and optimize the overdrive coefficient, and the image display device itself has a means for measuring the response speed (response speed measuring unit 78). The coefficient is optimized, and it is possible to display a moving image by overdrive suitable for the user's environment for a long period of time, and provide a liquid crystal display having high moving image display quality and reliability to the user.

  DESCRIPTION OF SYMBOLS 10, 70 ... Signal processing part 11, 71 ... Overdrive drive part, 12, 72 ... Display panel, 13, 73 ... Memory | storage part, 14, 74 ... Temperature detection part, 15, 75 ... Time monitoring part, 16, 76 ... Control unit, 51 ... Outside air temperature detection unit, 61 ... Rotation direction detection unit, 77 ... Test pattern generation unit, 78 ... Response speed measurement unit, 111 ... Look-up table

Claims (4)

Based on the overdrive coefficient determined by the current frame image and the immediately preceding frame image, an overdrive drive unit having a look-up table for performing overdrive drive of the display panel;
A temperature detector for detecting the temperature of the display panel;
A storage unit for storing a plurality of overdrive coefficients suitable for the detected temperature;
A time monitoring unit for monitoring the elapsed time of operation of the display panel when returning from a startup or hibernation state;
From the plurality of overdrive coefficients suitable for the temperature information acquired from the temperature detection unit, an optimum overdrive coefficient is selected using the operation elapsed time information acquired from the time monitoring unit, and the lookup table is selected. A control unit to be set;
An image display device comprising: It further includes an outside air temperature detecting unit for detecting outside air temperature outside,
The control unit uses the difference between the temperature information acquired from the temperature detection unit and the outside air temperature information acquired from the outside air temperature detection unit, and the operation elapsed time information of the display panel acquired from the time monitoring unit. The image display apparatus according to claim 1, wherein an optimal overdrive coefficient is selected from the overdrive coefficients stored in the storage unit and set in the lookup table. A rotation direction detection unit for detecting a rotation direction in a use state of the display panel;
The control unit includes temperature information acquired from the temperature detection unit, operation elapsed time information of the display panel acquired from the time monitoring unit, and rotation direction information of the display panel acquired from the rotation direction detection unit. A control unit for selecting an overdrive coefficient stored in the storage unit and setting it in the lookup table;
The image display apparatus according to claim 1, further comprising: An overdrive coefficient optimization method in an image display device having a look-up table for performing overdrive driving of a display panel based on an overdrive coefficient determined by a current frame image and an immediately preceding frame image,
Detecting the temperature of the display panel;
Monitoring the elapsed operation time of the display panel when the image display device is restored from a startup or hibernation state;
Using the detected temperature information and the monitored operation elapsed time information, an optimum overdrive coefficient is selected from a plurality of overdrive coefficients suitable for the temperature stored in advance in a storage unit, Setting in the lookup table;
Performing overdrive driving of the display panel based on the overdrive coefficient set in the lookup table;
A method for optimizing an overdrive coefficient in an image display device.

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