JP2005345552A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display an excellent image by suppressing luminance distortion between luminance of a backlight and transmittance of a liquid crystal panel to a minimum. <P>SOLUTION: The liquid crystal display device is equipped with: a picture data feature extraction part 103 which detects temperature of the liquid crystal panel 108 with a temperature sensor 111 mounted in the vicinity of the liquid crystal panel 108 and outputs a signal Up/Down to judge a direction of variation of transmittance of the panel; and a timing correcting means 112 to correct a timing of setting the luminance value of the backlight corresponding to the panel temperature and the direction of the transmittance variation. Furthermore, the liquid crystal display device is constructed in such a way that the timing of setting the luminance of the backlight is corrected so as to make the timing of varying the luminance of the backlight always follow the timing of variation of the transmittance of the liquid crystal panel 108, even if the transition time of the transmittance of the liquid crystal panel 108 varies in accordance with the temperature, or even if the transition time differs in accordance with the direction of variation of the transmittance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device that includes a liquid crystal panel and a backlight disposed on the back surface thereof, and displays an image while changing the relative relationship between the transmittance of the liquid crystal panel and the backlight luminance based on the feature amount of image data. .

  In general, liquid crystal display devices are widely used as image display devices such as mobile phone devices and portable information terminal devices. In this type of liquid crystal display device, the number of pixels of the liquid crystal panel has been increased and the pixel size has been miniaturized in recent years in order to enhance the expressiveness of display images.

  Since the transmittance of the liquid crystal panel of the liquid crystal display device decreases as the number of pixels increases and the pixel size becomes finer, it is necessary to make the luminance of the backlight, which is a light source disposed on the back surface, brighter. .

  However, in a battery-driven liquid crystal display device, if the brightness of the backlight of the liquid crystal panel is made brighter, the power consumption increases and the drive duration is shortened.

  Therefore, in recent liquid crystal display devices, the maximum luminance in the image data constituting one image is obtained, and the luminance of the video signal is increased according to the margin for the maximum luminance that can be expressed by the liquid crystal panel. A method of reducing power consumption by reducing the luminance of the backlight has been proposed (for example, see Patent Document 1).

  On the other hand, as the light source of the backlight, generally, either one or both of a cold cathode tube and a white LED are used. The luminance of the backlight using the cold cathode tube as a light source is generally not suitable for dynamically changing the light emission amount because of its long response transition time.

  Note that the transmittance transition waveform due to the transmittance change of the liquid crystal panel is expressed in an exponential function, so that the determination time of the transmittance transition is slow. Relative to the fixed transition time of the liquid crystal panel, the brightness of the backlight using the white LED as a light source changes sharply and the transition time is short.

  Therefore, as this type of liquid crystal display device, the backlight luminance transition waveform is adjusted to complement the transmittance transition waveform of the liquid crystal panel by changing the drive current of the white LED stepwise and integrating and smoothing this. In order to reduce the distortion of luminance when the luminance of the backlight and the transmittance of the liquid crystal panel change at the same time, there has been proposed (for example, see Patent Document 2).

  A conventional liquid crystal display device will be described with reference to FIGS. 7, 8 and 9. FIG. FIG. 7 is a block diagram showing a configuration of a conventional liquid crystal display device. As shown in FIG. 7, the liquid crystal display device includes a liquid crystal panel drive circuit 7, a liquid crystal panel 8, a white LED 9, and a white LED drive circuit 10.

  In FIG. 7, the vertical synchronizing signal VSYNC, the horizontal synchronizing signal HSYNC, the image data transfer clock PCLK, and the pixel data R ′, G ′, B ′ constituting the image are input to the liquid crystal panel drive circuit 7 at the timing shown in FIG. Is done.

  The liquid crystal panel drive circuit 7 generates an applied voltage corresponding to each pixel of the liquid crystal panel 8 in accordance with the pixel data R ′, G ′, B ′ constituting the image. The liquid crystal panel 8 determines the transmittance based on the applied voltage.

  A serial clock signal SCLK, backlight luminance data SDATA, and a backlight luminance data confirmation signal STROBE are input to the white LED driving circuit 10 at the timing shown in FIG. The white LED driving circuit 10 performs digital / analog conversion on the backlight luminance data SDATA input in the serial format at the falling edge timing of the backlight luminance data determination signal STROBE, and outputs a driving current for the white LED 9.

  The white LED 9 is disposed on the back surface of the liquid crystal panel 8, emits light substantially in proportion to the drive current supplied from the white LED drive circuit 10, and irradiates the liquid crystal panel 8 having transmittance based on image data. As a result, a predetermined image is displayed on the panel surface (not shown) of the liquid crystal panel 8.

  Here, the relationship between the change in the transmittance of the liquid crystal panel 8, the change in the light emission luminance of the white LED 9, and the combined luminance of both will be described with reference to FIG. FIG. 10 is a timing diagram of luminance waveforms in the conventional liquid crystal display device shown in FIG. In FIG. 10, in order from the top, the vertical synchronization signal VSYNC, the pixel data R ′, G ′, B ′ constituting the image, the backlight luminance data determination signal STROBE, the transmittance of the liquid crystal panel 8, and the back by the light emission of the white LED 9. The combined luminance on the panel surface of the liquid crystal panel 8 obtained by multiplying the light luminance, the transmittance of the liquid crystal panel 8 and the luminance of the white LED 9 is shown.

  In FIG. 10, symbol τ1 is a delay time from the falling edge of the vertical synchronization signal VSYNC until the liquid crystal panel drive circuit 7 starts driving. Symbol τ2 is a delay time from the fall of the vertical synchronization signal VSYNC to the fall of the backlight luminance data determination signal STROBE.

  The image displayed on the panel surface of the liquid crystal panel 8 is displayed as a combined luminance of both the transmittance of the liquid crystal panel 8 and the light emission luminance of the white LED 9. Therefore, in this conventional liquid crystal display device, as described above, the luminance of the video signal is increased in accordance with the margin for the maximum luminance that can be expressed by the liquid crystal panel 8, and the power consumption is reduced by reducing the luminance of the backlight accordingly. In order to suppress this, the relative relationship between the delay time τ1 and the delay time τ2 is adjusted so that the timing of the change in the luminance of the backlight and the transmittance of the liquid crystal panel 8 is matched.

The luminance response of the white LED 9 is generally determined by a steep change relative to the rise and fall of the transmittance response of the liquid crystal panel 8 that slowly changes exponentially. For this reason, before and after both the luminance of the backlight and the transmittance of the liquid crystal panel 8 change at the same time, a sudden rise or drop (luminance distortion) occurs in the combined luminance waveform of both. In the conventional liquid crystal display device, the relative relationship between the delay time τ1 and the delay time τ2 is determined so as to minimize such luminance distortion.
JP 11-65531 A JP 2003-330424 A

  However, in the conventional liquid crystal display device as shown in FIG. 7, it is generally known that the response transition time of the transmittance of the liquid crystal panel 8 largely varies depending on the change in the ambient temperature. Further, in the conventional liquid crystal display device, as shown in the liquid crystal panel transmittance waveform shown in FIG. 10, the transmittance changes sharply at a high temperature and the transition time is short, but the transition time becomes very long at a low temperature. End up. Furthermore, it is known that in the conventional liquid crystal display device, there is a difference in response time between the direction in which the transmittance increases and the direction in which the transmittance decreases.

  For this reason, in the conventional liquid crystal display device, even if the relative relationship between the delay time τ1 and the delay time τ2 is adjusted so as to minimize the luminance distortion at room temperature, if the temperature is lower or higher, FIG. The transition response time of the liquid crystal panel shown in FIG. As a result, in the conventional liquid crystal display device, a timing mismatch with a change in backlight luminance occurs, resulting in a larger luminance distortion of the combined luminance, and human flickering in the image displayed on the panel surface of the liquid crystal panel 8 is caused by human flickering. There was a problem that the image quality was deteriorated by being recognized by the eyes.

  Further, in the liquid crystal display device described in Patent Document 1, it is necessary to prepare a drive circuit for changing the backlight luminance waveform in a stepwise manner for each change temperature, so that the circuit scale becomes very large.

  The present invention has been made in view of the above points. Even when the transmittance transition time of the liquid crystal panel fluctuates due to a change in ambient temperature, the luminance of the backlight and the liquid crystal can be changed by following the change in the luminance of the backlight. It is an object of the present invention to provide a liquid crystal display device that can display a good image while minimizing luminance distortion with respect to the transmittance of the panel.

  In order to solve such a problem, a liquid crystal display device of the present invention includes a liquid crystal panel showing a transmittance according to each pixel data constituting an image, and a backlight that illuminates the liquid crystal panel from the back, and the liquid crystal display A liquid crystal display device that displays an image according to image data on a panel, and outputs an image correction parameter, a backlight luminance value, and a change direction of an image luminance component for the input image data from a feature amount of the input image data Data feature amount extraction means, image data correction means for correcting the image data by reflecting the image correction parameters obtained by the image data feature amount extraction means to the input image data, and the image data feature amount A light control means for determining a light emission amount of the backlight based on the backlight luminance value obtained by the extraction means; A temperature detecting means for detecting the temperature of the liquid crystal panel arranged in contact with the light, and dimming for adjusting the setting timing of the backlight luminance value from the temperature obtained by the temperature detecting means and the change direction of the image luminance component And a timing correction means.

  According to this configuration, the panel temperature of the liquid crystal panel is detected by the temperature detecting means arranged in the vicinity of the liquid crystal panel. Further, the change direction of the panel transmittance of the liquid crystal panel is determined by the image data feature amount extraction means. Then, the dimming timing adjusting means adjusts the setting timing of the backlight luminance value according to the panel temperature and the change direction of the panel transmittance. Accordingly, even when the transition time of the liquid crystal panel varies depending on the panel temperature and when the transition time varies depending on the direction of change of the panel transmittance, the transmission timing of the liquid crystal panel is always changed. The timing of the luminance change of the backlight can be matched. Therefore, according to this configuration, it is possible to suppress luminance distortion caused by a change between the luminance of the backlight and the transmittance of the liquid crystal panel, and it is possible to perform good image display.

  According to the present invention, even if the transmittance transition time of the liquid crystal panel fluctuates due to a change in the ambient temperature or the transition time varies depending on the change direction of the transmittance of the liquid crystal panel, the timing of the change in the transmittance of the liquid crystal panel It is possible to follow the change timing of the luminance of the backlight, and it is possible to suppress the luminance distortion between the luminance of the backlight and the transmittance of the liquid crystal panel and perform a good image display.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, components having the same configuration or function and corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a block diagram of a liquid crystal display device according to an embodiment of the present invention. As shown in FIG. 1, a liquid crystal display device 100 according to the present embodiment includes an image memory 101, an image data correction unit 102, an image data feature amount extraction unit 103, a timing generation unit 104, and a liquid crystal interface unit (LCD IF) 105. , A dimming interface unit (P / S IF) 106, a liquid crystal panel driving circuit 107, a liquid crystal panel 108, a white LED 109, a white LED driving circuit 110, a temperature sensor 111, and a dimming timing correction unit 112.

  In FIG. 1, an image memory 101 is a storage unit that temporarily stores image data input to the liquid crystal display device 100. The image data correction unit 102 is image data correction means for reflecting an image correction parameter to pixel data constituting an image. The image data feature amount extraction unit 103 is an image data feature amount extraction unit that calculates a feature amount from each pixel data constituting an image and outputs an image correction parameter and a backlight luminance value.

  The timing generation unit 104 instructs the timing for sequentially reading the image data stored in the image memory 101 from the image memory 101 as the signal RGB. In addition, the timing generation unit 104 instructs the liquid crystal interface unit 105 and the dimming timing correction unit 112 to transmit image data transfer timing and backlight luminance value transfer timing, respectively.

  The liquid crystal interface unit 105 outputs pixel data R ′, G ′, and B ′ that constitute an image along with the vertical synchronization signal VSYNC, the horizontal synchronization signal HSYNC, and the image data transfer clock PCLK.

  The dimming interface unit 106 transfers the backlight luminance value in a serial format at a given timing.

  The liquid crystal panel drive circuit 107 drives the liquid crystal panel 108. The liquid crystal panel 108 displays an image.

  The white LED 109 is a backlight disposed on the back surface of the liquid crystal panel 108 and illuminates the liquid crystal panel 108 from the back surface. The white LED driving circuit 110 determines a current to be given to the white LED 109 from the backlight luminance value.

  The temperature sensor 111 is disposed in the vicinity of the liquid crystal panel 108 and is a temperature detection unit that detects the temperature of the liquid crystal panel 108.

  The dimming timing correction unit 112 is dimming timing correction means for correcting the backlight luminance setting timing based on the temperature of the liquid crystal panel 108 detected by the temperature sensor 111.

  Next, the operation of the liquid crystal display device 100 according to the present embodiment will be described.

  In FIG. 1, image data input to the liquid crystal display device 100 is temporarily stored in the image memory 101. The image data stored in the image memory 101 is sequentially read out as a signal RGB from the image memory 101 in accordance with an instruction from the timing generation unit 104 and sent to the image data correction unit 102 and the image data feature amount extraction unit 103.

  The image data feature amount extraction unit 103 obtains feature amounts such as the maximum value, the minimum value, and the average value of the luminance component for each pixel data constituting one screen, and the image data correction parameter for the original image data is obtained from the result. And determine the backlight brightness value.

  For example, when the luminance component of the original image data is lower than the maximum allowable gradation, the image correction parameter for increasing the luminance component is output, and the backlight luminance value is the value for decreasing the issued amount. On the other hand, when the luminance component of the original image data reaches almost the maximum value of the allowable gradation, an image correction parameter that decreases the luminance component is output, and a value that increases the light emission amount is output as the backlight luminance value. .

  Further, the image data feature amount extraction unit 103 causes the dimming timing correction unit 112 to increase the luminance of the corrected image output from the image data correction unit 102 as compared to the luminance of the previous correction image. Assuming that the signal Up / Down = 1, the signal is output for each image unit as 0 when descending.

  Next, the image data correction unit 102 corrected the luminance component by reflecting the image correction parameter obtained by the image data feature amount extraction unit 103 on the original image data read from the image memory 101. Pixel data R ′, G ′, B ′ constituting the image is output.

  In FIG. 1, as an example, pixel data R ′, G ′, and B ′ that constitute an image output from the image data correction unit each have an 8-bit gradation.

  The timing generation unit 104 instructs the liquid crystal interface unit 105 and the dimming timing correction unit 112 for the image data transfer timing and the backlight luminance value transfer timing, respectively.

  The liquid crystal interface unit 105 generates a vertical synchronization signal VSYNC, a horizontal synchronization signal HSYNC, and an image data transfer clock PCLK based on the timing control signal output from the timing generation unit 104, and configures an image from the image data correction unit 102. Pixel data R ′, G ′, B ′ to be output to the liquid crystal panel drive circuit 107. Here, R ′, G ′, and B ′ are 6 bits each, which indicates a case where color reduction processing is performed in accordance with the number of gradations of the liquid crystal panel 108, and is not changed from the gist of the present invention. Needless to say.

  The liquid crystal panel drive circuit 107 applies to the pixels of the liquid crystal panel 108 from pixel data R ′, G ′, B ′ constituting the image sent together with the vertical synchronization signal VSYNC, horizontal synchronization signal HSYNC, and image data transfer clock PCLK. Generate voltage. The liquid crystal panel 108 displays an image on the panel surface with the transmittance based on the applied voltage.

  On the other hand, the dimming timing correction unit 112 has a correspondence table of transmittance transition times with respect to the temperature of the liquid crystal panel 108. This correspondence table is a table divided into a case where the transmittance increases and a case where the transmittance decreases.

  The dimming timing correction unit 112 also includes liquid crystal panel temperature information detected by the temperature sensor 111 disposed in the vicinity of the liquid crystal panel 108, a signal Up / Down from the image data feature amount extraction unit 103, and timing generation. An instruction for backlight luminance value transfer timing is input from the unit 104.

  The dimming timing adjustment unit 112 corrects the backlight luminance setting timing input from the timing generation unit 104 from the liquid crystal panel temperature information and the signal Up / Down, and then changes the transmittance of the liquid crystal panel 108. A timing signal of the backlight luminance setting timing when the amount reaches almost the center is output to the dimming interface unit 106.

  The dimming interface unit 106 performs parallel / serial conversion on the backlight luminance value 8 bits input from the image data feature amount extraction unit 103 in accordance with the timing signal output from the dimming timing correction unit 112, and generates signals SDATA, SCLK, STROBE is output.

  The white LED drive circuit 110 determines the drive current for the white LED 109 by digital / analog conversion of the backlight luminance value 8 bits serially transferred from the dimming interface unit 106 at the falling edge of the signal STROBE. Then, the white LED drive circuit 110 supplies the transmitted light to the liquid crystal panel by emitting light from the white LED 109 disposed on the back surface of the liquid crystal panel 108 with the determined drive current. Here, since the brightness of the white LED 109 is substantially proportional to the drive current, the brightness of the white LED 109 can be adjusted by controlling the drive current.

  Next, the above operation will be described with reference to a timing chart focusing on the relationship between the transmittance response of the liquid crystal panel 108 and the light emission timing of the backlight luminance.

  FIG. 2 shows an image when the liquid crystal display device according to the present embodiment does not perform image data correction and backlight luminance control, that is, without reflecting the result of the image data feature amount extraction unit 103 in FIG. FIG.

  In FIG. 2, in order from the top, the vertical synchronization signal VSYNC, the pixel data R ′, G ′, B ′ constituting the image, the backlight luminance setting timing signal STROBE, the transmittance response waveform of the liquid crystal panel 108, and the backlight luminance waveform. 4 shows a combined luminance waveform obtained by combining the transmittance response waveform of the liquid crystal panel 108 and the backlight luminance.

  In FIG. 2, symbol τ <b> 1 is a delay time from the fall of the vertical synchronization signal VSYNC until the transmittance of the liquid crystal panel 108 starts to change, and corresponds to the processing delay time of the liquid crystal panel drive circuit 107.

  As shown in FIG. 2, when the result of the image data feature amount extraction unit 103 is not reflected, the input image data becomes the pixel data R ′, G ′, B ′ constituting the image as it is. The transmittance response waveform is the transmittance waveform itself based on the input image. In this example, the transmittance of the liquid crystal panel 108 gradually decreases for each frame, that is, the image becomes darker.

  In FIG. 2, symbol τ2 is a delay time from the fall of the vertical synchronization signal VSYNC to the fall of the backlight setting timing signal STROBE. As shown in FIG. 2, when the result of the image data feature amount extraction unit 103 is not reflected, the backlight luminance value is constant, so the backlight luminance waveform is also constant. In addition, since the composite luminance waveform is expressed as a product of the transmittance response waveform and the backlight luminance, the transmittance response waveform of the liquid crystal panel 108 maintains the shape as it is, and a dark image gradually appears for each frame. It shows how it is displayed.

  FIG. 3 reflects the result of the image data feature amount extraction unit 103 in FIG. 1 when image data correction and backlight luminance control of the liquid crystal display device according to the present embodiment are performed, so that the image data correction is performed. FIG. 6 is a timing chart when the dimming of backlight luminance is reflected.

  As described above, in an image in which the input image gradually becomes dark, the transmittance of the liquid crystal panel 108 has a high margin with respect to the maximum transmittance of 100%, so that the transmittance of the liquid crystal panel 108 is gradually increased. The luminance component of the image data output from the image data correction unit 102 is corrected.

  As a result, the transmittance response waveform of the liquid crystal panel 108 is a waveform in which the transmittance gradually increases. At this time, the signal output by the image data feature amount extraction unit 103 is Up / Down = 1.

  On the other hand, the backlight luminance value output from the image data feature amount extraction unit 103 is controlled to decrease in accordance with the gradually increasing transmittance of the liquid crystal panel 108. As a result, the backlight luminance waveform gradually decreases at the timing of the signal STROBE for each frame. That is, the power consumed for the backlight gradually decreases.

  The composite luminance waveform gradually decreases in the same manner as that in FIG. 2, but some luminance distortion occurs before and after the change in the transmittance waveform of the liquid crystal panel 108 and the change in the backlight luminance waveform overlap.

  Here, the delay time τ2 is the temperature vs. transmittance when the luminance increases, which the dimming timing correction unit 112 has from the temperature of the liquid crystal panel 108 detected by the temperature sensor 111 in FIG. 1 and the signal Up / Down. The backlight luminance setting timing is determined with reference to the transition time characteristic table. That is, in the liquid crystal display device 100, even when the transmittance transition time of the liquid crystal panel 108 varies depending on the ambient temperature, the backlight luminance setting timing always follows the timing when it almost reaches the center of the transmittance change amount. The luminance distortion that appears in the combined luminance waveform is suppressed to a minimum.

  Here, the transmittance transition time with respect to the temperature of the liquid crystal panel 108 will be described with reference to FIG. FIG. 4 is a diagram showing the relationship between the temperature of the liquid crystal panel 108 of the liquid crystal display device 100 according to the present embodiment and the transmittance transition time (response time).

  The transmittance transition time is a time required to change from the current transmittance to the next transmittance, and this value varies greatly from several ms to several hundred tens of ms depending on the temperature. Further, the transmittance transition time of the liquid crystal panel 108 is characterized in that it differs depending on whether the transmittance of the liquid crystal panel 108 increases or decreases.

  The image data feature amount extraction unit 103 has two tables denoted by reference characters τd and τr in FIG. 4. Transmission of τd when the signal Up / Down = 0 and transmission of τr when the signal Up / Down = 1. By selecting the rate transition time characteristic table, the backlight setting timing acts to compensate the temperature.

  Next, referring to FIGS. 5 and 6, the liquid crystal display device 100 undergoes a temperature change, and the combined luminance waveform shown in FIG. 2 is deformed to change the transmittance transition time of the liquid crystal panel 108. explain.

  FIG. 5 is a timing chart at a high temperature of the liquid crystal display device according to the present embodiment, that is, a timing chart when the temperature of the liquid crystal panel 108 becomes higher than the case of FIG. In this case, the response of the transmittance of the liquid crystal panel 108 becomes faster due to the temperature rise.

  Therefore, in this case, the dimming timing correction unit 112 instructs the backlight luminance setting timing to be earlier from the temperature information detected by the temperature sensor 111 and the signal Up / Down. As a result, the backlight luminance setting timing STROBE output from the dimming interface unit 106 is advanced so as to coincide with the timing at which the liquid crystal panel 108 reaches almost the center of the amount of change in transmittance. With this operation, in the liquid crystal display device 100, the luminance distortion appearing in the combined luminance waveform is suppressed to the smallest state.

  FIG. 6 is a timing chart at a low temperature of the liquid crystal display device according to the present embodiment, that is, a timing chart when the temperature of the liquid crystal panel 108 becomes lower than the case of FIG. In this case, the response of the transmittance of the liquid crystal panel 108 becomes slower due to the temperature drop.

  Therefore, in this case, the dimming timing correction unit 112 instructs to delay the backlight luminance setting timing from the temperature information detected by the temperature sensor 111 and the signal Up / Down. Accordingly, the backlight luminance setting timing STROBE output from the dimming interface unit 106 is delayed so as to coincide with the timing at which the change amount of the liquid crystal panel transmittance reaches approximately the center. With this operation, in the liquid crystal display device 100, the luminance distortion appearing in the combined luminance waveform is suppressed to the smallest state.

  Incidentally, here, the description has been made by taking up an image in which the input image becomes gradually dark. However, when the input image becomes gradually bright, the image data is set so that the transmittance of the liquid crystal panel 108 is gradually lowered. Is compensated. That is, in this case, since the signal Up / Down = 0, the temperature at which the dimming timing compensation unit 112 has the brightness decreases from the temperature detected by the temperature sensor 111 and the signal Up / Down. The backlight luminance setting timing is determined with reference to a table of transmissivity transition time characteristics.

  As described above, in the liquid crystal display device 100, even if the transmittance transition time of the liquid crystal panel 108 varies depending on the ambient temperature, the backlight luminance setting timing STROBE output from the dimming interface unit 106 always has the transmittance. By following the timing when the change amount reaches almost the center, the luminance distortion appearing in the combined luminance waveform is suppressed to a minimum.

  As described above, in the liquid crystal display device 100 according to the embodiment of the present invention, the backlight luminance value is adjusted by the dimming timing correction unit 112 according to the panel temperature of the liquid crystal panel 108 and the transmittance change direction. The setting timing can be adjusted. Therefore, in the liquid crystal display device 100, even if the transmittance transition time of the liquid crystal panel 108 varies depending on the temperature, and even when the transition time varies depending on the change direction of the transmittance, the transmission of the liquid crystal panel 108 is always performed. By combining the timing of the rate change and the timing of the backlight luminance change, it is possible to suppress the luminance distortion caused by the change between the transmittance of the liquid crystal panel 108 and the luminance of the backlight and perform a good image display. it can.

  The liquid crystal display device according to the present invention always matches the timing of the change of the transmittance of the liquid crystal panel and the timing of the change of the backlight luminance, and the luminance generated by the change between the transmittance of the liquid crystal panel and the luminance of the backlight. Since it has the effect of suppressing distortion and good image display and reducing power consumption, it is equipped with a liquid crystal panel and a backlight placed on the back side under various temperature environments. This is useful as a portable device for displaying images.

1 is a block diagram of a liquid crystal display device according to an embodiment of the present invention. Timing chart when image data compensation and backlight luminance control are not performed in the liquid crystal display device according to the embodiment of the present invention FIG. 4 is a timing chart when image data correction and backlight luminance adjustment are performed in the liquid crystal display device according to the embodiment of the present invention. The figure which shows the relationship between the temperature of the liquid crystal panel of the liquid crystal display device which concerns on one embodiment of this invention, and the transmittance | permeability transition time. Timing chart at high temperature of liquid crystal display device according to one embodiment of the present invention Timing chart at low temperature of liquid crystal display device according to one embodiment of the present invention Block diagram showing the configuration of a conventional liquid crystal display device Timing chart of image data transfer in a conventional liquid crystal display device Timing diagram of backlight luminance value transfer in a conventional liquid crystal display device Timing diagram of luminance waveform in a conventional liquid crystal display device

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Image memory 102 Image data correction part 103 Image data feature-value extraction part 104 Timing generation part 105 Liquid crystal interface part 106 Light control interface part 107 Liquid crystal panel drive circuit 108 Liquid crystal panel 109 White LED
110 White LED Drive Circuit 111 Temperature Sensor 112 Light Control Timing Compensation Unit

Claims (5)

A liquid crystal panel showing transmittance according to each pixel data constituting the image;
A backlight for illuminating the liquid crystal panel from the back,
A liquid crystal display device that displays an image according to image data on the liquid crystal panel,
Image data feature amount extraction means for outputting an image correction parameter, a backlight luminance value, and a change direction of the image luminance component for the input image data from the feature amount of the input image data;
Image data correction means for correcting the image data by reflecting the image correction parameters obtained by the image data feature amount extraction means to the input image data;
A light control means for determining the light emission amount of the backlight based on the backlight luminance value obtained by the image data feature amount extraction means;
Temperature detecting means for detecting the temperature of the liquid crystal panel disposed in proximity to the liquid crystal panel;
A liquid crystal display device comprising: a dimming timing correction unit that adjusts a setting timing of the backlight luminance value from a temperature obtained by the temperature detection unit and a change direction of the image luminance component.   2. The liquid crystal display device according to claim 1, wherein the dimming timing correction means includes storage means for storing a transmittance transition time using the temperature of the liquid crystal panel and the change direction of the transmittance as parameters. . A liquid crystal panel showing transmittance according to each pixel data constituting the image;
A liquid crystal display method for displaying an image according to image data on the liquid crystal panel of a liquid crystal display device comprising a backlight for illuminating the liquid crystal panel from the back,
An image data feature amount extraction step for outputting an image correction parameter, a backlight luminance value, and a change direction of the image luminance component for the input image data from the feature amount of the input image data;
An image data correction step of correcting the image data by reflecting the image correction parameters obtained in the image data feature amount extraction step with respect to the input image data;
A dimming step for determining a light emission amount of the backlight based on the backlight luminance value obtained in the image data feature amount extraction step;
Dimming timing for adjusting the setting timing of the backlight luminance value from the temperature obtained by the temperature detecting means that is disposed in the vicinity of the liquid crystal panel and detects the temperature of the liquid crystal panel and the change direction of the image luminance component A liquid crystal display method comprising: a correction step.   4. The liquid crystal display method according to claim 3, wherein the dimming timing correction step stores a transmittance transition time using the temperature of the liquid crystal panel and the change direction of the transmittance as parameters.   A portable terminal device comprising the liquid crystal display device according to claim 1.

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