JP4290479B2 - LCD television equipment - Google Patents

LCD television equipment Download PDF

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Publication number
JP4290479B2
JP4290479B2 JP2003147300A JP2003147300A JP4290479B2 JP 4290479 B2 JP4290479 B2 JP 4290479B2 JP 2003147300 A JP2003147300 A JP 2003147300A JP 2003147300 A JP2003147300 A JP 2003147300A JP 4290479 B2 JP4290479 B2 JP 4290479B2
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Japan
Prior art keywords
luminance
image
liquid crystal
light emission
signal
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JP2003147300A
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JP2004350179A (en
Inventor
立美 森
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船井電機株式会社
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention More particularly, the present invention relates to a liquid crystal television apparatus that improves the image quality of an image displayed on a liquid crystal display surface. .
[0002]
[Prior art]
Conventionally, as a technique for improving the image quality (for example, contrast) of an image displayed on a liquid crystal display surface, a technique for correcting the luminance of each pixel of display data forming an image displayed on the liquid crystal display surface is known. (For example, refer to Patent Document 1, Patent Document 2, and Patent Document 3.)
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 4-11281
[Patent Document 2]
JP-A-62-262028
[Patent Document 3]
JP-A 63-261229
[0004]
[Problems to be solved by the invention]
In the above-described conventional apparatus, display data to be displayed on the liquid crystal display surface is analyzed, predetermined control data is fed back according to the analysis, and image processing is executed on the display data based on the control data Therefore, since the image quality of the image is improved, the processing is complicated.
[0005]
The present invention has been made in view of the above problems, and can improve the image quality (for example, contrast) of an image displayed on a liquid crystal display surface by a simple method. LCD television equipment The purpose is to provide
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a liquid crystal panel in which a display surface is formed by a plurality of pixels; The number of pixels that make up the liquid crystal panel A backlight unit disposed on the back surface of the liquid crystal panel and emitting the same light emitter to irradiate the display surface of the liquid crystal panel from the back surface; and A backlight drive circuit that emits light at a predetermined light emission intensity by applying a voltage to each light emitter, and a television signal having a desired frequency corresponding to a television broadcast band via an antenna are received. A tuner that selects only the required signal from the received television signal, outputs a high-frequency amplified analog video signal that has been converted to an intermediate frequency signal, and a predetermined signal level of the analog video signal that is input from the tuner An analog / digital conversion circuit that converts the range to a digital signal with a gradation corresponding to each signal level, and the converted digital signal A digital signal processing circuit that performs predetermined digital signal processing to generate a digital video signal, and a digital video signal that forms an image for one screen displayed on the liquid crystal panel while inputting the generated digital video signal A frame memory circuit for storing the image, a liquid crystal driver circuit for displaying the image on the liquid crystal panel while performing predetermined signal processing on the digital video signal stored in the frame memory, and a microcomputer for controlling the circuits. In the liquid crystal television apparatus, the image is displayed based on the digital video signal stored in the frame memory circuit. At least 2 or more Divided image brightness that averages the brightness of each pixel for each divided image And the overall image brightness and And the microcomputer is calculated by the luminance calculation circuit. Entire image And the difference between the divided image brightness calculated by the brightness calculation circuit and the difference is Represents the state of light emission brightness that is excessively bright or dark It is determined whether or not the difference is equal to or greater than the difference threshold, and when the difference is equal to or greater than the difference threshold and the image luminance is higher than the divided image luminance, the emission luminance of the corresponding light emitting area is reduced and the difference is increased. Is equal to or greater than the difference threshold value and the image brightness is smaller than the divided image brightness, the light emission brightness of the corresponding light emitting area in the backlight unit is increased, and each light emitting area corresponding to each divided image is increased. By applying a predetermined voltage based on the increase / decrease of the light emission luminance to the light emitter of the backlight unit, the light emission luminance of the light emission region is individually adjusted in accordance with each divided image luminance.
[0007]
In the liquid crystal television apparatus according to the present invention, when an image is displayed on a liquid crystal panel having a display surface formed of a plurality of pixels, the tuner receives a television signal having a desired frequency corresponding to the television broadcast band via an antenna. Then, only a required signal is selected from the received television signal, amplified at a high frequency, and an analog video signal converted into an intermediate frequency signal is output. The analog / digital conversion circuit receives an analog video signal from the tuner, converts a predetermined signal level range of the analog video signal into a digital signal having a gradation corresponding to each signal level, and the digital signal processing circuit A predetermined digital signal process is performed on the converted digital signal to generate a digital video signal.
[0008]
Here, the frame memory circuit stores the digital video signal that forms an image for one screen displayed on the liquid crystal panel while inputting the digital video signal generated by the digital signal processing circuit, and the liquid crystal driver circuit Then, the image is displayed on the liquid crystal panel while performing predetermined signal processing on the digital video signal stored in the frame memory. Further, the backlight unit irradiates the display surface of the liquid crystal panel from the back side by causing the arranged matrix-like light emitters to emit light. The backlight unit emits light by a backlight driving circuit. In such a case, the backlight driving circuit applies a voltage to each light emitter of the backlight unit to cause each light emitter to emit light with a predetermined light emission luminance. In each of these circuits, the microcomputer controls the circuit to realize a function as a liquid crystal television device.
[0009]
As described above, the backlight unit illuminates the display surface from the back surface of the liquid crystal panel by causing the light emitter to emit light. At this time, a predetermined voltage is applied from the backlight drive circuit to each light emitter of the backlight unit, and each light emitter emits light with a predetermined luminance corresponding to the applied voltage. Here, an image based on the digital video signal is displayed on the liquid crystal panel. The brightness of the image of the digital video signal changes appropriately according to the content of the image. On the other hand, when the backlight unit emits light with a predetermined luminance regardless of the luminance change of the image, if the image is bright, the luminance of the image and the luminance of the backlight unit may make the user feel dazzling. It can happen. On the other hand, when the image is dark, the visibility of the image may be lowered only by the luminance of the backlight unit emitting light at a predetermined luminance. Further, the brightness of an image is often different for each image area according to the content of the image. At this time, by changing the light emission luminance of the backlight unit in a region where the luminance is higher or lower than the average luminance of the entire image, the image quality can be improved if the contrast of the region with respect to the entire image can be enhanced. This is preferable.
[0010]
Therefore, in the invention according to claim 1 configured as described above, a luminance calculation circuit is provided, and the image is obtained in a predetermined number based on the digital video signal stored in the frame memory circuit by the luminance calculation circuit. A divided image luminance is calculated by averaging the luminance of each pixel for each divided divided image. Then, based on the divided image brightness calculated by the microcomputer, the backlight driving circuit is controlled, and a predetermined voltage is applied to the light emitter of the backlight portion of each light emitting area corresponding to each divided image. The light emission brightness of each light emitting area is individually adjusted in accordance with the divided image brightness. In this way, by changing the light emission luminance of the backlight unit for each divided image in accordance with the divided image luminance, the display data for forming the image displayed on the liquid crystal panel can be simplified without performing image processing. An image having a desired contrast can be acquired by a simple method.
[0011]
With the configuration described above, the image quality of an image can be improved by a simple method by appropriately changing the light emission luminance in each light emission region of the backlight unit corresponding to the divided image luminance. On the other hand, the technical idea is not limited to a specific device to which the technology is applied, that is, a liquid crystal television device, but a backlight that controls the light emission luminance of the backlight in a corresponding region according to the divided image luminance. It goes without saying that it can also be realized as a light control device.
[0012]
Therefore, image data acquisition means for acquiring image data displayed on the liquid crystal display surface formed by a plurality of pixels, and each pixel in each divided image obtained by dividing the image by a predetermined number based on the acquired image data A luminance calculating means for calculating a divided image luminance obtained by averaging the luminances of the liquid crystal, and a light emission unit disposed on the back surface of the liquid crystal display surface, capable of emitting light from the back surface of the liquid crystal display surface, and corresponding to the division of the image A backlight unit capable of adjusting the light emission luminance for each region and a backlight control unit for individually adjusting the light emission luminance of each corresponding light emission region based on the calculated divided image luminances may be provided. .
[0013]
In the invention configured as described above, when the image data acquisition unit acquires the image data displayed on the liquid crystal display surface formed by a plurality of pixels, the luminance calculation unit calculates the image based on the acquired image data. A divided image luminance is calculated by averaging the luminance of each pixel in each divided image divided by a predetermined number. Here, the backlight means disposed on the back surface of the liquid crystal display surface emits light from the back surface with respect to the liquid crystal display surface. At this time, the backlight means can adjust the light emission luminance for each light emission region corresponding to the division of the image. Then, the backlight control unit individually adjusts the light emission luminance of each corresponding light emission region based on each divided image luminance calculated by the luminance calculation unit.
[0014]
Further, the luminance calculation means calculates an image luminance obtained by averaging the luminance of each pixel of the image, and the backlight control means determines whether the calculated image luminance is equal to or greater than a predetermined maximum luminance threshold value. If the image brightness is determined to be equal to or greater than the maximum brightness threshold, the light emission brightness of the entire light emission region in the backlight unit may be reduced.

In the invention configured as described above, the luminance calculation means calculates the image luminance obtained by averaging the luminance of each pixel of the image. Then, the backlight control means determines whether or not the calculated image brightness is equal to or greater than a predetermined maximum brightness threshold. Here, when the backlight control unit determines that the image luminance is equal to or higher than the maximum luminance threshold value, the backlight control unit reduces the emission luminance of the entire light emitting region in the backlight unit.
[0015]
Further, the luminance calculation means calculates an image luminance obtained by averaging the luminance of each pixel of the image, and the backlight control means determines whether the calculated image luminance is equal to or less than a predetermined minimum luminance threshold value. If the image brightness is determined to be equal to or less than the same minimum brightness threshold, the light emission brightness of all the light emitting areas in the backlight unit may be increased.

In the invention configured as described above, the luminance calculation means calculates the image luminance obtained by averaging the luminance of each pixel of the image. Then, the backlight control means determines whether or not the calculated image luminance is equal to or less than a predetermined minimum luminance threshold. Here, when the backlight control means determines that the image brightness is equal to or lower than the minimum brightness threshold, the backlight control means increases the light emission brightness of the entire light emission area in the backlight means.
[0016]
Further, image data acquisition means for acquiring image data displayed on a liquid crystal display surface formed by a plurality of pixels, and each pixel in each divided image obtained by dividing the image by a predetermined number based on the acquired image data A luminance calculating means for calculating a divided image luminance obtained by averaging the luminances of the liquid crystal, and a light emission unit disposed on the back surface of the liquid crystal display surface, capable of emitting light from the back surface of the liquid crystal display surface, and corresponding to the division of the image Backlight control means capable of adjusting the light emission brightness for each region, and the backlight control means calculates the difference between the calculated image brightness and the calculated divided image brightness and Is equal to or greater than a predetermined difference threshold, and if the difference is equal to or greater than the difference threshold and the image luminance is greater than the divided image luminance, the corresponding light emitting region emits light. Degree may reduced to configure.
In the invention configured as described above, Then, the difference between the image brightness calculated by the brightness calculation means and the divided image brightness calculated by the brightness calculation means is calculated by the backlight control means. Here, the backlight control means determines whether or not the calculated difference is greater than or equal to a predetermined difference threshold value. And when it determines with the said difference being more than a difference threshold value, the light emission brightness | luminance of the corresponding light emission area | region in a backlight means is reduced.
[0017]
Further, the backlight control means calculates a difference between each calculated divided image brightness and the calculated image brightness, determines whether the difference is equal to or greater than a predetermined difference threshold, and When the difference is equal to or greater than the difference threshold and the image brightness is lower than the divided image brightness, the light emission brightness of the corresponding light emitting area in the backlight unit may be increased.
In the invention configured as described above Then, the difference between the divided image brightness calculated by the brightness calculating means and the image brightness calculated by the brightness calculating means is calculated by the backlight control means. Here, the backlight control means determines whether or not the calculated difference is greater than or equal to a predetermined difference threshold value. And when it determines with the said difference being more than a difference threshold value, the light emission brightness | luminance of the corresponding light emission area | region in a backlight means is increased.
[0018]
It goes without saying that the above-described backlight control device can also be established as a method thereof, and it goes without saying that the invention is also realized as a program that enables a computer to realize an equivalent function in the backlight control device.
[0019]
【The invention's effect】
As described above, the present invention performs image processing on display data forming an image displayed on the liquid crystal panel by changing the light emission luminance of each light emission region corresponding to the backlight unit according to the divided image luminance. Therefore, it is possible to provide a liquid crystal television device capable of acquiring an image having a desired contrast by a simple method.

Further, it is possible to provide a backlight control device capable of improving the image quality of an image by a simple method by individually adjusting the light emission luminance for each light emission region corresponding to the divided image according to the divided image luminance. it can. Furthermore, when the entire image is very bright, that is, when the luminance is equal to or higher than the luminance indicated by the maximum luminance threshold, it is possible to reduce glare that the user can feel by reducing the light emission luminance of the entire light emitting region.

Further, when the entire image is very dark, that is, below the luminance indicated by the minimum luminance threshold, it is possible to improve the visibility of the image by increasing the light emission luminance of the entire light emitting region.
[0020]
Further, by reducing the light emission luminance of the light emission region corresponding to the dark divided image with respect to the entire image, it is possible to further reduce the luminance of the divided image portion and enhance the contrast of the image.
Furthermore, by increasing the light emission luminance of the light emission region corresponding to the bright divided image with respect to the entire image, it is possible to further increase the luminance of the divided image portion and enhance the contrast of the image.
Further, it is possible to provide a backlight control method capable of improving the image quality of an image by a simple method by individually adjusting the light emission luminance for each light emission region corresponding to the divided image according to the divided image luminance. it can.
Further, it is possible to provide a backlight control program capable of improving the image quality of an image by a simple method by individually adjusting the light emission luminance for each light emission region corresponding to the divided image according to the divided image luminance. it can.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Here, embodiments of the present invention will be described in the following order.
(1) Configuration of the liquid crystal television device:
(2) Processing content of emission luminance control processing:
(3) Modification:
(4) Correspondence with the present invention:
(5) Summary:
[0022]
(1) Configuration of the liquid crystal television device:
FIG. 1 is a block diagram showing the configuration of an embodiment of a liquid crystal television device according to the present invention.
In FIG. 1, a liquid crystal television apparatus 10 is roughly composed of a tuner 11, a video signal processing circuit 12, a liquid crystal panel 13, a microcomputer 14, and a selector circuit 15. The video signal processing circuit 12 has a digital signal processing circuit 12a and a liquid crystal driver circuit 12b inside, and a microcomputer I / F 12d and a luminance calculation circuit 12f are connected via a bus 12e such as an IIC bus. . A microcomputer 14 is connected to the microcomputer I / F, and the microcomputer 14 can control each circuit of the video signal processing circuit 12 via the microcomputer I / F 12d.
[0023]
Here, an operation panel 14a, a remote control I / F 14b, a ROM 14c, a RAM 14d, and a backlight drive circuit 14e are connected to the microcomputer 14, and the microcomputer 14 reads various control programs stored in advance in the ROM 14c, The RAM 14d is executed as a work area, and the control of each circuit described above is executed. Further, the backlight unit 14e1 is connected to the backlight drive circuit 14e1. Here, the resolution of the liquid crystal panel 13 is not particularly limited, but in this embodiment, as shown in FIG. 2, the pixels M (1, 1) to M (640, 480) are arranged in the vertical and horizontal directions. The resolution is the size of pixel * 480 pixels (VGA size).
[0024]
Of course, this resolution may be a resolution of 1024 pixels * 768 pixels (XGA size). The backlight unit 14e1 connected to the backlight drive circuit 14e is disposed on the back surface of the liquid crystal panel 13, and as shown in FIG. 3, the pixels M (1,1) to M ( 640,480) is equivalent to the light emitter elements L (1,1) to L (640,480), and the light emitter elements L (1,1) to L (640,480) are arranged in a matrix. As shown in FIG. 4, the backlight 14 is individually driven by the backlight drive circuit 14e based on the control of the microcomputer 14 so as to emit light with a predetermined light emission luminance.
[0025]
At this time, the backlight drive circuit 14e applies a predetermined voltage to each of the light emitter elements L (1, 1) to L (640, 480) based on a predetermined control signal input from the microcomputer 14. Here, FIG. 5 shows the relationship between the voltage applied to each of the light emitting elements L (1, 1) to L (640, 480) from the backlight drive circuit 14e and the light emission luminance. In the drawing, the horizontal axis defines the voltage V, and the vertical axis defines the light emission luminance Y of each of the light emitter elements L (1, 1) to L (640, 480). The backlight drive circuit 14e can apply a voltage of 0 to V1 to the light emitter elements L (1, 1) to L (640, 480) based on the control signal of the microcomputer 14, and each light emitter element L ( 1, 1) to L (640, 480) emit light substantially corresponding to the voltage change of 0 to V1, and at this time, the luminance changes to 0 to Y1.
[0026]
The tuner 11 is a tuner for analog television, and receives television broadcast radio waves with a connected antenna 11a. The tuner 11 outputs a television broadcast signal (composite video signal) as an analog video signal based on the received television broadcast radio wave. The liquid crystal television apparatus 10 also receives an external input terminal 15a for inputting an analog video signal (composite video signal) from the VTR as an external input terminal, and an analog video signal (composite video signal) from the LD player. And an external input terminal 15c for inputting an analog video signal (composite video signal) from the DVD player.
[0027]
The tuner 11 and the external input terminals 15a to 15c are connected to the selector circuit 15. The composite video signal (television broadcast signal) output from the tuner 11 and the composite video signal input from the external input terminal 15a and the external input. One composite video signal can be selected from the composite video signal input from the terminal 15b and the composite video signal input from the external input terminal 15c. This selection is performed by an operation by a remote controller that is input via an operation panel 14a connected to the microcomputer 14 and a remote controller I / F 14b. The composite video signal selected by the selector circuit 15 is sent to the video signal processing circuit 12. The sent composite video signal is input to the digital signal processing circuit 12 a inside the video signal processing circuit 12.
[0028]
The digital signal processing circuit 12a includes an analog / digital conversion circuit 12a1, a Y / C separation circuit 12a2, a chroma decoder circuit 12a3, an image quality adjustment circuit 12a4, and a matrix circuit 12a5. In such a configuration, when the analog / digital conversion circuit 12a1 receives a composite video signal, a predetermined signal level range between a white level and a black level in the composite video signal is converted into a digital signal having a gradation corresponding to each signal level. Convert to Subsequent predetermined signal processing is executed based on this digital signal. The Y / C separation circuit 12a2 performs separation processing into a Y signal and a C signal based on this digital signal. The separated Y signal and C signal are input to the chroma decoder circuit 12a3 and subjected to predetermined signal processing. Later, it is output as a YUV signal.
[0029]
The image quality adjustment circuit 12a4 of the digital signal processing circuit 12a adjusts sharpness, color, and TINT for the YUV signal. The matrix circuit 12a5 performs an RGB matrix conversion process on the YUV signal whose image quality has been adjusted by the image quality adjustment circuit 12a4 to generate an RGB signal. The generated RGB signal is sent to the liquid crystal driver circuit 12b. The liquid crystal driver circuit 12b includes a pixel number conversion circuit 12b1, an image quality adjustment circuit 12b2, an output processing circuit 12b3, and a frame memory 12b4. The pixel number conversion circuit 12b1 receives the RGB signal generated by the digital signal processing circuit 12a, and performs an RGB signal for one screen displayed on the liquid crystal panel 13 while performing a scaling process on the RGB signal. Generate. Then, the RGB signals for one screen are stored in the frame memory 12b4 as pixel information.
[0030]
The image quality adjustment circuit 12b2 of the liquid crystal driver circuit 12b is subjected to scaling processing by the pixel number conversion circuit 12b1, and adjusts brightness, contrast, black balance, and white balance for the RGB signal stored in the frame memory 12b4. Do. The output processing circuit 12b3 performs gamma correction, dither processing, etc. on the RGB signal whose image quality has been adjusted by the image quality adjustment circuit 12b2, and adds a background signal, an OSD signal, a blanking signal, etc. To display the image.
[0031]
As described above, the liquid crystal television device 10 having the configuration according to the present embodiment causes each of the light emitter elements L (1, 1) to L (640, 480) of the backlight unit 14e1 to emit light, thereby causing each of the liquid crystal panels 13 to emit light. The pixels M (1, 1) to (640, 480) are irradiated from the back side. At this time, as described above, the predetermined voltage V is applied from the backlight driving circuit 14e to each of the light emitter elements L (1, 1) to L (640, 480) of the backlight unit 14e1, and each of the light emitter elements. L (1, 1) to L (640, 480) emit light at a predetermined light emission luminance Y corresponding to the voltage V. Here, as described above, the liquid crystal panel 13 displays an image based on pixel information composed of RGB signals for one screen stored in the frame memory 12b4. The brightness of this image changes appropriately according to the content of the image.
[0032]
On the other hand, when the backlight unit 14e1 irradiates the liquid crystal panel 13 with a constant light emission luminance Y regardless of the luminance change of the image, If the image to be displayed is bright, the brightness of the image and the light emission luminance Y of the backlight unit 14e1 may cause the user to feel dazzling. On the other hand, when the displayed image is dark, the visibility of the image may be lowered only by the light emission luminance Y of the backlight unit 14e1 emitting light at a predetermined light emission luminance. Further, the displayed image often has different luminance for each image area in accordance with the content of the image. At this time, if the contrast of the region relative to the entire image can be enhanced by changing the light emission luminance of the backlight unit 14e1 in a region where the luminance is higher or lower than the average luminance of the entire image, the image quality is improved. It is possible to improve, which is preferable.
[0033]
Therefore, in the present embodiment, the light emission luminance Y of each of the light emitter elements L (1, 1) to L (640, 480) of the backlight unit 14e1 is changed according to the luminance of the image displayed on the liquid crystal panel 13. . That is, by changing the light emission luminance Y of the backlight unit 14e1, it is possible to realize an appropriate contrast according to the displayed image and improve the visibility of the image. At this time, the brightness calculation circuit 12f is divided into the image brightness of the entire image or each divided by a predetermined division method based on pixel information composed of RGB signals for one screen stored in the frame memory 12b4. The divided image brightness for each divided image is calculated. Then, the light emitter elements L (1, 1) to L (640, 480) of the backlight unit 14e1 are configured substantially corresponding to the entire divided image or the divided image in accordance with a predetermined correspondence relationship based on the image luminance or the divided image luminance. The light emission luminance Y is changed for each light emitting region formed by the light emitting elements L (1,1) to L (640,480) of the backlight portion 14e1.
[0034]
FIG. 6 is a configuration diagram showing an embodiment of a division mode when the liquid crystal panel 13 is divided.
In this figure, in this embodiment, the liquid crystal panel 13 is divided into divided images W1 to W9. Then, the luminance calculation circuit 12f calculates individual divided image luminances C1 to C9 from the pixel data included in each of the divided images W1 to W9. As the calculation method of the divided image luminances C1 to C9, the luminance is calculated for each pixel from the RGB data in the pixel information by using an existing luminance calculation method, and an average of these is calculated. Here, the divided image luminance C1 indicates the average luminance of the divided image W1, the divided image luminance C2 indicates the average luminance of the divided image W2, and the divided image luminance C3 indicates the average luminance of the divided image W3. The divided image luminance C4 indicates the average luminance of the divided image W4.
The divided image luminance C5 indicates the average luminance of the divided image W5, the divided image luminance C6 indicates the average luminance of the divided image W6, the divided image luminance C7 indicates the average luminance of the divided image W7, and the divided image The luminance C8 indicates the average luminance of the divided image W8, and the divided image luminance C9 indicates the average luminance of the divided image W9.
[0035]
FIG. 7 is a configuration diagram showing an embodiment of a division mode of the backlight unit 14e1 divided corresponding to the division of the liquid crystal panel 13. As shown in FIG.
In the figure, the backlight unit 14e1 is divided into light emitting regions R1 to R9 corresponding to the divided images W1 to W9 of the liquid crystal panel 13 described above. Needless to say, this division is a logical division and is not physically divided. And the backlight drive circuit 14e outputs a predetermined voltage for each light emission area | region R1-R9, and makes it light-emit with the predetermined light emission brightness Y. FIG. That is, the light emitting elements R (1, 1) to L (640, 480) included in the same light emitting region R1 to R9 are individually applied to each light emitting region R1 to R9 so that the same voltage V is applied. The light emission luminance Y can be changed. In the present embodiment, the liquid crystal panel 13 is divided into nine divided images W1 to W9, and the backlight unit 14e1 is divided into nine light emitting regions R1 to R9 correspondingly. However, the division mode is of course not limited, and may be divided into two divided images, or may be divided into n divided images, and the number of divided images is designed. Needless to say, it is a matter.
[0036]
(2) Processing content of emission luminance control processing:
Based on the above-described division mode, the microcomputer 14 executes the following light emission luminance control process to control the light emission luminance Y for each of the light emission regions R1 to R9. FIG. 8 is a flowchart showing the processing contents of the light emission luminance control processing.
In the figure, when pixel information composed of RGB signals for one screen stored in the frame memory 12b4 is updated (step S104), the microcomputer 14 receives each pixel from the frame memory 12b4 via the microcomputer I / F 12d. Each pixel information of M (1, 1) to (640, 480) is read (step S105). Then, the luminance of the pixels M (1, 1) to (640, 480) is calculated based on the read pixel information.
[0037]
Then, the luminance calculated for each of the divided images W1 to W9 is averaged to calculate the divided image luminances C1 to C9 (step S110), and the average luminance of all the pixels M (1,1) to (640,480). A certain image brightness Cw is calculated (step S115). Next, it is determined whether or not the image brightness Cw is greater than or equal to a predetermined maximum brightness threshold h. Here, in the present embodiment, the reference voltage VB is applied to each of the light emitting elements L (1, 1) to L (640, 480) of the backlight unit 14e1 as a default as shown in FIG. It is assumed that each of the light emitting elements L (1, 1) to L (640, 480) emits light with the reference luminance YB based on the reference voltage VB. In such a situation, the above-described maximum luminance threshold value h is set to a value that allows the user to feel dazzle with the luminance that is the sum of the reference luminance YB and the image luminance Cw (step S120).
[0038]
If it is determined in step S120 that the image brightness Cw is greater than or equal to the maximum brightness threshold h, it is determined that the entire image is in a very bright state, and all the light emitter elements L (1, 1, The light emission luminance YB of 1) to (640, 480) is reduced. Specifically, a value obtained by subtracting a predetermined minute voltage ΔV from the reference voltage VB is substituted for the control voltage V, and the light emitter elements L (1, 1) to L (640, 480) emit light by the control voltage V. (Step S125). Thereby, it becomes possible to reduce the brightness | luminance of the whole image, and it becomes possible to suppress the glare which a user can feel when seeing an image. If it is determined in step S120 that the image brightness Cw is less than the maximum brightness threshold h, it is determined whether or not the image brightness Cw is less than or equal to the minimum brightness threshold l.
[0039]
The minimum luminance threshold value l is set to a value that reduces the visibility of the image when the image is displayed at a luminance that is the sum of the reference luminance YB and the image luminance Cw (step S130). Here, when it is determined that the image luminance Cw is equal to or less than the minimum luminance threshold l, it is determined that the entire image is in a very dark state, and all the light emitter elements L (1, 1) to ((1) to ( 640, 480) is increased. Specifically, a value obtained by adding a predetermined minute voltage ΔV from the reference voltage VB is substituted for the control voltage V, and the light emitter elements L (1, 1) to L (640, 480) emit light by the control voltage V. (Step S135). As a result, it is possible to increase the brightness of the entire image and improve the visibility of the image. On the other hand, if it is determined in step S130 that the image brightness Cw is equal to or less than the minimum brightness threshold value l, the control voltage V is set to VB, and all light emitter elements (1, 1) to 1B are set at the default light emission brightness YB. L (640, 480) is caused to emit light (step S136).
[0040]
Next, the light emission luminances of the light emitting regions R1 to R9 corresponding to the divided images W1 to W9 are controlled based on the luminance state of the divided image luminances C1 to C9 with respect to the image luminance Cw. First, in order to detect the luminance state of the divided image W1, 1 is substituted into the parameter k (step S140), and | image luminance Cw−divided image luminance Ck | is calculated (step S145). Then, it is determined whether or not the value of | image brightness Cw−divided image brightness Ck | is equal to or greater than a predetermined threshold value S. The threshold value S is set to a value that can determine whether each area of the divided images W1 to W9 is excessively bright or excessively dark compared to the image brightness Cw of the entire image ( Step S150). If it is determined in step S150 that the value of | image luminance Cw−divided image luminance Ck | is greater than or equal to a predetermined threshold S, it is determined whether or not the image luminance Cw is greater than the divided image luminance Ck ( Step S155).
[0041]
When it is determined that the image luminance Cw is higher than the divided image luminance Ck, it is determined that the portion of the divided image Wk is dark with respect to the entire image, and the emission luminance of the light emitting region Rk corresponding to the divided image Wk is reduced. . Specifically, a value obtained by subtracting a predetermined minute voltage ΔV from the control voltage V is substituted into a new control voltage V, and the light emitting elements L (1, 1) to L existing in the light emitting region Rk by this control voltage V are substituted. (640, 480) is caused to emit light (step S160). Thereby, the brightness of the divided image Wk can be lowered as compared with the surroundings, so that the contrast can be enhanced and the image quality can be improved. On the other hand, when the image luminance Cw is smaller than the divided image luminance Ck, it is determined that the portion of the divided image Wk is bright with respect to the entire image, and the emission luminance of the light emitting region Rk corresponding to the divided image Wk is increased.
[0042]
Specifically, a value obtained by adding a predetermined minute voltage ΔV from the control voltage V is substituted into the new control voltage V, and the light emitting elements L (1, 1) to L existing in the light emitting region Rk by the control voltage V are substituted. (640, 480) is caused to emit light (step S165). Thereby, the brightness of the divided image Wk can be increased compared to the surroundings, so that the contrast can be enhanced and the image quality can be improved. The above processing is executed up to the divided image W9 (step S170).
[0043]
(3) Modification:
In the above-described embodiment, a method of increasing or decreasing the constant minute voltage ΔV from the reference voltage VB or the control voltage V is employed to increase or decrease the emission luminance of the divided image luminances C1 to C9. In this way, the constant minute voltage ΔV may be increased or decreased, or the minute voltage ΔV to be increased or decreased may be changed. In such a case, if the image brightness Cw is changed in correspondence with the degree of difference between the maximum brightness threshold value h, or is changed in correspondence with the degree of difference between the image brightness Cw and the minimum brightness threshold value l, it is adapted to the image state. Brightness can be achieved, which is preferable. Similarly, it is preferable to change based on the difference between the image luminance Cw and each of the divided images C1 to C9 because it is possible to realize contrast enhancement suitable for the image state.
[0044]
(4) Correspondence with the present invention:
The correspondence between the configuration in the embodiment described above and the configuration in the present invention will be added. The liquid crystal panel according to the present invention corresponds to the liquid crystal panel 13, and the tuner according to the present invention corresponds to the tuner 11. The analog / digital conversion circuit according to the present invention corresponds to the analog / digital conversion circuit 12a1, and the signal processing circuit according to the present invention corresponds to the digital signal processing circuit 12a excluding the analog / digital conversion circuit 12a1. The frame memory circuit according to the present invention corresponds to the frame memory 12b4, and the liquid crystal driver circuit according to the present invention corresponds to the liquid crystal driver circuit 12b excluding the frame memory circuit 12b4.
[0045]
The function of the luminance calculation circuit according to the present invention is realized by the luminance calculation circuit 12f, and the microcomputer according to the present invention is realized by the microcomputer 14. The image data acquisition unit according to the present invention corresponds to the frame memory 12b4 that acquires and stores pixel information for one screen while inputting the generated digital video signal, and the luminance calculation unit is connected to the luminance calculation circuit 12f. Correspond. The backlight means corresponds to the backlight unit 14e1, and the backlight control means corresponds to the microcomputer 14 and the backlight drive circuit 14e.
[0046]
(5) Summary:
In this way, the image luminance Cw and the divided image luminances C1 to C9 are calculated. When the image luminance Cw is equal to or greater than the maximum luminance threshold h, the emission luminances of all the light emitter elements L (1,1) to L (640,480). The glare that the user can feel is suppressed by reducing the brightness, and when the image brightness Cw is less than or equal to the minimum brightness threshold l, the light emission brightness of all the light emitter elements L (1, 1) to L (640, 480) is increased. This makes it possible to improve the visibility of the image. Further, the image quality is improved by enhancing the contrast of the corresponding divided images W1 to W9 by increasing or decreasing the emission luminance of the corresponding light emitting regions R1 to R9 based on the state of the divided image luminances C1 to C9 with respect to the image luminance Cw. It becomes possible to improve.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of a liquid crystal television device according to the present invention.
FIG. 2 is a configuration diagram showing a configuration of a liquid crystal panel 13;
FIG. 3 is a configuration diagram showing a configuration of a backlight unit 14e1.
FIG. 4 is a configuration diagram showing a control system of a backlight unit 14e1.
FIG. 5 is a diagram illustrating a correspondence relationship between an applied voltage V and light emission luminance Y.
6 is a configuration diagram showing an embodiment of a division mode of the liquid crystal panel 13. FIG.
FIG. 7 is a configuration diagram showing an embodiment of a dividing mode of the backlight unit 14e1.
FIG. 8 is a flowchart showing processing contents of light emission luminance control processing.
FIG. 9 is a diagram showing a correspondence relationship between an applied voltage V and light emission luminance Y.
[Explanation of symbols]
10 ... Liquid crystal television device
11 ... Tuner
11a ... antenna
12 ... Video signal processing circuit
12a ... Digital signal processing circuit
12a1 ... analog / digital conversion circuit
12a2 ... YC separation circuit
12a3 ... chroma decoder circuit
12a4 ... Image quality adjustment circuit
12a5 ... Matrix circuit
12b ... Liquid crystal driver circuit
12b1... Pixel number conversion circuit
12b2: Image quality adjustment circuit
12b3 ... Output processing circuit
12b4 ... Frame memory
12d: Microcomputer I / F
12e ... Bus
12f ... Luminance calculation circuit
13 ... LCD panel
14 ... Microcomputer
14a ... operation panel
14b ... Remote control I / F
14c ... ROM
14d ... RAM
14e ... Backlight drive circuit
14e1 ... Backlight
15 ... Selector circuit
15a: External input terminal (VTR)
15b ... External input terminal (LD)
15c ... External input terminal (DVD)

Claims (1)

  1. A liquid crystal panel having a display surface formed of a plurality of pixels, and a light emitting body arranged in a matrix in the same number as the pixels constituting the liquid crystal panel, and disposed on the back surface of the liquid crystal panel and having the same light emission A backlight unit that emits light from the body and irradiates the display surface of the liquid crystal panel from the back side, and a backlight that causes each light emitter to emit light at a predetermined light emission luminance by applying a voltage to each light emitter of the backlight unit Analog video that receives a television signal of a desired frequency corresponding to the television broadcast band via a light driving circuit and an antenna, and selects only the required signal from the received television signal, amplifies it at high frequency, and converts it to an intermediate frequency signal A tuner that outputs a signal, and an analog video signal input from the tuner, and a predetermined signal level range of the analog video signal is set according to each signal level. An analog / digital conversion circuit that converts the digital signal into a digital signal, a digital signal processing circuit that performs predetermined digital signal processing on the converted digital signal to generate a digital video signal, and the generated digital video signal In addition, a frame memory circuit for storing a digital video signal for forming an image for one screen displayed on the liquid crystal panel, and a predetermined signal processing for the digital video signal stored in the frame memory are performed on the liquid crystal panel. In a liquid crystal television device comprising a liquid crystal driver circuit for displaying the image and a microcomputer for controlling the circuits,
    Luminance calculation for calculating the divided image luminance obtained by averaging the luminance of each pixel for each divided image obtained by dividing the image into at least two based on the digital video signal stored in the frame memory circuit, and the image luminance of the entire image Have a circuit,
    The microcomputer calculates the difference between the image luminance of the entire image calculated by the luminance calculation circuit and the divided image luminance calculated by the luminance calculation circuit,
    It is determined whether or not the difference is equal to or greater than a difference threshold that represents a state of light emission luminance that is excessively bright or dark . The difference is equal to or greater than the difference threshold, and the image luminance is higher than the divided image luminance. Is too large, the light emission brightness of the corresponding light emitting area is reduced,
    When the difference is equal to or greater than the difference threshold and the image luminance is smaller than the divided image luminance, the emission luminance of the corresponding light emitting region in the backlight unit is increased,
    By applying a predetermined voltage based on the increase / decrease of the light emission luminance to the light emitter of the backlight section of each light emission region corresponding to each divided image, the light emission luminance of the same light emission region is made to correspond to each divided image luminance. A liquid crystal television device characterized by being individually adjusted.
JP2003147300A 2003-05-26 2003-05-26 LCD television equipment Expired - Fee Related JP4290479B2 (en)

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