JP2006330222A - Liquid crystal display device and its temporal deterioration correcting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device that eliminates the need for a complicated control circuit for a luminance sensor and a feedback control circuit, and thus, can facilitate control and can be made compact and low-priced, and to provide a liquid crystal display device capable of correcting the temporal luminance deterioration by areas. <P>SOLUTION: The liquid crystal display device is equipped with a cumulative power-on time memory 7 which stores a cumulative power-on time obtained by accumulating power-on times; a time lapse luminance setting memory 5 which stores luminance setting value for making the luminance of a lamp for a backlight that is nearly constant by compensating luminance deterioration of the lamp 3 for the backlight, with respect to the cumulative power-on time; and lamp luminance control means 1 and 2 for reading the corresponding luminance setting value stored in the temporal luminance setting memory 5, according to the cumulative power-on time stored in the cumulative power-on time memory 7 and adjusting the luminance of the lamp 3 for the backlight with the read luminance setting value. Furthermore, the luminance unevenness is corrected by correction means 13, 15, and 16 of correcting temporal luminance deterioration by the areas. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device capable of reducing deterioration with time of a backlight and a method for correcting deterioration with time.

  The backlight illumination system used in liquid crystal display devices includes a direct light system that directly irradiates light from the light source from the back of the liquid crystal display panel, and a sidelight that irradiates the liquid crystal display panel with light from the light source via a light guide plate. There is a method (or edge light method). Recently, with the increase in size of liquid crystal display devices, the direct type has been increasingly adopted.

  For the backlight, a light source such as a cold cathode tube or an EL element is used. However, these light sources are deteriorated with time, and the luminance gradually decreases as the usage time elapses. Although this time-dependent deterioration characteristic depends on the type of light source used, an approximate characteristic indicates an accumulated energization time-luminance characteristic with a downward slope as shown in FIG. The life of a cold cathode tube is usually said to be 20,000 to 30,000 hours.

  As conventional techniques for correcting the deterioration of the backlight light source over time, for example, Japanese Patent Application Laid-Open No. 11-295589 (Patent Document 1), Japanese Patent Application Laid-Open No. 11-295589 (Patent Document 2), and Japanese Patent Application Laid-Open No. 2004-163479. (Patent Document 3) and JP-A-2005-91526 (Patent Document 4).

Further, the liquid crystal display screen has uneven brightness due to the backlight light source.
As conventional techniques for correcting the luminance unevenness caused by such a backlight light source, JP-A-8-94845 (Patent Document 5), JP-A-2004-109205 (Patent Document 6), JP-A-6-313883. There are a gazette (patent document 7) and Unexamined-Japanese-Patent No. 10-170919 (patent document 8).

  For example, FIG. 8 shows an arrangement of cold cathode tubes used as a light source of a backlight of a liquid crystal display device. In FIG. 8, reference numeral 41 denotes a U-shaped cold cathode tube. Reference numeral 42 denotes a casing to which the cold cathode tube 41 is attached. FIG. 8 shows a state in which the cold cathode tubes 41 are attached to the casing 42 and arranged. The casing 42 serves as a mounting frame for the cold cathode tube 41 and also serves as a reflector. Although not shown in FIG. 8, the liquid crystal display device further includes a liquid crystal display panel, a light diffusion plate, and the like. These liquid crystal display panel, light diffusing plate, cold cathode tube 41 and casing 42 are assembled by being overlaid as shown in FIG. 1 of Japanese Patent Laid-Open No. 8-94845 (Patent Document 5), for example.

  A cold cathode fluorescent lamp 41 having a U-shape as shown in FIG. 8 has a drive part 43 on one side and a bent part 44 on the other side as shown in the figure. The cold cathode tube 41 is characterized in that the drive unit 43 side is brighter (higher brightness) than the bent portion 44 side. This is a feature of a cold cathode tube having a U shape.

The liquid crystal display device in which the cold cathode tubes 41 having such characteristics are arranged and attached as shown in FIG. 8 is viewed from the display screen 45 side as shown in FIG. 45 _-1 bright, the bent portion 44 side _{45 -2} darkened, comes to have a brightness gradient (brightness unevenness). Note that the brightness gradient in the frame indicated by reference numeral 45 represents a schematic image.
JP-A-11-295589 JP-A-11-307245 JP 2004-163479 A JP-A-2005-91526 Japanese Patent Laid-Open No. 8-94845 JP 2004-109205 A JP-A-6-313883 JP-A-10-170919

  However, the conventional techniques disclosed in Patent Documents 1 to 4 for correcting deterioration with time are for detecting light from a backlight light source with a luminance sensor and performing feedback control so as to obtain a predetermined luminance. In addition, it requires a feedback control circuit, which complicates the control, increases the number of parts used, and has problems in miniaturization and cost reduction.

  Further, the luminance unevenness of the liquid crystal display screen in the above-mentioned Patent Documents 5 to 8 for correcting the luminance unevenness also varies with time for each area of the liquid crystal display screen. It could not be corrected.

In view of the above problems, an object of the present invention is to eliminate the need for a complicated control circuit and a luminance sensor for increasing the number of parts in a liquid crystal display device provided with a aging deterioration correction unit. It is an object of the present invention to provide a liquid crystal display device that is simple and can be reduced in size and price.
Another object of the present invention is to provide a liquid crystal display device provided with a brightness correction means for each area of the liquid crystal display screen, capable of correcting the luminance deterioration with time for each area, and a method for correcting the deterioration with time. Is to provide.

The subject matter of the first aspect of the present invention is a liquid crystal display device that includes a liquid crystal display panel and a backlight lamp that emits light from the back of the liquid crystal display panel, and displays display data on the liquid crystal display panel. A storage means for storing the accumulated energization time obtained by accumulating the energized time; and a lamp brightness control means for adjusting the brightness of the backlight lamp to be the same based on the accumulated energization time. It exists in the liquid crystal display device.
According to a second aspect of the present invention, there is provided a liquid crystal display that includes a liquid crystal display panel and a backlight lamp that emits light from the back surface of the liquid crystal display panel, and displays display data on the liquid crystal display panel. In the apparatus, an accumulated energization time memory for storing an accumulated energization time obtained by accumulating energized time, and compensating for luminance deterioration of the backlight lamp with respect to the accumulated energization time, thereby making the luminance of the backlight lamp substantially constant. A luminance setting value stored with time, a luminance setting value stored in the time-dependent luminance setting memory is read based on the cumulative energization time stored in the cumulative energization time memory, and the read luminance setting value Thus, the present invention resides in a liquid crystal display device comprising lamp luminance control means for adjusting the luminance of the backlight lamp.
The gist of the invention according to claim 3 of the present invention is that the luminance setting value stored in the temporal luminance setting memory is set so that the lowest luminance area of the display screen has a predetermined luminance. The liquid crystal display device according to claim 2.
According to a fourth aspect of the present invention, there is provided display data adjusting means for adjusting the plurality of areas into which the liquid crystal display panel is divided so that the luminance is substantially the same. It exists in the liquid crystal display device as described in any one of Claim 1 thru | or 3.
The gist of the invention according to claim 5 of the present invention is that the display data adjusting means has an area correction coefficient table storing an area correction coefficient for each of the plurality of areas, and is stored in the area correction coefficient table. 5. The liquid crystal display device according to claim 4, wherein correction data of display data is calculated with reference to an area correction coefficient.
The gist of the invention according to claim 6 of the present invention is that the area correction coefficient is stored as a plurality of area correction coefficient tables corresponding to the accumulated energization time, and corresponds to the accumulated energization time of the accumulated energization time memory. 6. The liquid crystal display device according to claim 5, wherein correction data of display data is calculated with reference to an area correction coefficient table.
According to a seventh aspect of the present invention, there is provided a liquid crystal display that includes a liquid crystal display panel and a backlight lamp that emits light from the back surface of the liquid crystal display panel, and displays display data on the liquid crystal display panel. In the apparatus, the accumulated energization time obtained by accumulating the energized time is stored, and is set for each area according to the accumulated energization time so that the luminances of the plurality of areas dividing the liquid crystal display panel are substantially the same. The present invention resides in a liquid crystal display device provided with a correction means for correcting by changing a correction coefficient.
According to an eighth aspect of the present invention, there is provided a liquid crystal display that includes a liquid crystal display panel and a backlight lamp that emits light from the back surface of the liquid crystal display panel, and displays display data on the liquid crystal display panel. In the apparatus, an accumulated energization time memory for accumulating and storing energized time, and an area correction coefficient for adjusting each area so that the luminance of a plurality of areas dividing the liquid crystal display panel is substantially the same. A plurality of temporal correction coefficient memories stored corresponding to the cumulative energization time, an area correction coefficient table storing the area correction coefficient corresponding to the cumulative energization time of the cumulative energization time memory, and the area correction coefficient table The present invention resides in a liquid crystal display device which calculates display data correction data with reference to the area correction coefficient.
The subject matter of claim 9 of the present invention is characterized by comprising alarm display means for displaying an alarm when the accumulated energization time reaches a predetermined life time. 9. The liquid crystal display device according to any one of 8 above.
According to a tenth aspect of the present invention, there is provided a time-dependent deterioration correction method for a liquid crystal display device that includes a backlight lamp that emits light from the back surface of the liquid crystal display panel and displays display data on the liquid crystal display panel. Storing the accumulated energization time obtained by accumulating the energized time, and adjusting the brightness of the backlight lamp to be the same based on the stored accumulated energization time. It exists in the correction method.
According to an eleventh aspect of the present invention, there is provided a time-dependent deterioration correction method for a liquid crystal display device that includes a backlight lamp that emits light from the back surface of the liquid crystal display panel and displays display data on the liquid crystal display panel. The accumulated energization time obtained by accumulating the energized time is stored, and the luminance setting value that makes the luminance of the backlight lamp substantially constant by compensating for the luminance degradation of the backlight lamp with respect to the accumulated energization time is set as the accumulated energization time. Corresponding storage, reading a brightness setting value corresponding to the stored cumulative energization time, and adjusting a brightness of a backlight lamp according to the read brightness setting value Lies in the way.
The gist of the invention according to claim 12 of the present invention is that the stored luminance setting value is set so that the lowest luminance area of the display screen has a predetermined luminance. 11. A method for correcting deterioration with time of a liquid crystal display device according to item 11.
According to a thirteenth aspect of the present invention, in the area where the liquid crystal display panel is divided into a plurality of areas, the plurality of areas are adjusted to have substantially the same luminance. It exists in the aging degradation correction method of the liquid crystal display device as described in any one of Claims 10 thru | or 12.
The gist of the invention according to claim 14 of the present invention is that the correction data of the display data is calculated with reference to an area correction coefficient table storing an area correction coefficient for each of the plurality of areas. 13. The method of correcting deterioration with time of the liquid crystal display device according to item 13.
The gist of the invention according to claim 15 of the present invention is that the area correction coefficient is stored as a plurality of area correction coefficient tables corresponding to the accumulated energization time, and the area correction corresponding to the stored accumulated energization time. 15. The method according to claim 14, wherein correction data for display data is calculated with reference to a coefficient table.
According to a sixteenth aspect of the present invention, there is provided a backlight deterioration lamp for irradiating light from the back surface of a liquid crystal display panel, and a method for correcting deterioration over time of a liquid crystal display device that displays display data on the liquid crystal display panel. The accumulated energization time obtained by accumulating the energized time is stored, and the correction set for each area according to the accumulated energization time so that the luminances of the plurality of areas dividing the liquid crystal display panel are substantially the same. The present invention resides in a method for correcting deterioration over time of a liquid crystal display device, wherein correction is performed by changing a coefficient.
According to a seventeenth aspect of the present invention, there is provided a backlight deterioration lamp for irradiating light from the back surface of a liquid crystal display panel, and a method for correcting deterioration with time of a liquid crystal display device that displays display data on the liquid crystal display panel. In the above, the energized time is accumulated and stored in the accumulated energized time memory, and the area correction coefficient for adjusting each area so that the luminance of the plurality of areas dividing the liquid crystal display panel is almost the same is accumulated. A plurality of storages corresponding to energization time, and correction data of display data is calculated with reference to the area correction coefficient corresponding to the accumulated energization time of the accumulated energization time memory. Lies in the way.
The gist of the invention according to claim 18 of the present invention is that it comprises alarm display means for displaying an alarm when the accumulated energization time reaches a predetermined life time. 17. The method for correcting deterioration with time of a liquid crystal display device according to any one of 17 above.

According to the present invention, there is no need for a complicated control circuit, and there is no need for a luminance sensor that increases the number of parts. Therefore, the time-dependent deterioration correction means that is easy to control and can be reduced in size and price. There is an effect that a liquid crystal display device having the above can be provided.
Further, according to the present invention, there is an effect that it is possible to provide a liquid crystal display device capable of correcting the luminance deterioration with time for each area of the liquid crystal display screen.

The best mode for carrying out the present invention will be specifically described with reference to the drawings.
(First embodiment)
FIG. 1 shows a control circuit configuration of a liquid crystal display device according to a first embodiment of the present invention.
Reference numeral 1 denotes a microcomputer (hereinafter referred to as a microcomputer) that controls the entire control circuit. Reference numeral 2 denotes a lamp brightness control circuit. Reference numeral 3 denotes a backlight lamp in which cold cathode tubes 41 are arranged as shown in FIG. Reference numeral 4 denotes a liquid crystal display panel for inputting display data and displaying video and characters.

  The microcomputer 1 inputs the luminance setting value 6 from the temporal luminance setting memory 5 and adjusts the luminance of the backlight lamp 3 by the lamp luminance control circuit 2. The brightness adjustment by the brightness setting value 6 is not the brightness unevenness adjustment but the overall brightness.

Reference numeral 7 denotes a cumulative energization time memory. A clock 8 outputs time data of the current time. The cumulative energization time memory 7 accumulates and stores the energization time of the liquid crystal display device based on the time data from the clock 8. The microcomputer 1 reads the accumulated energization time stored in the accumulated energization time memory 7, and reads the luminance setting value corresponding to the accumulated energization time in the elapsed luminance setting memory 5. Thereby, the microcomputer 1 operates the lamp brightness control circuit 2 to adjust the brightness of the backlight lamp 3 based on the brightness setting value 6 so that the brightness of the backlight lamp 3 becomes substantially constant regardless of the passage of time. The cumulative energization time memory 7 uses a non-volatile memory such as E ² PROM or a battery-backed memory, and stores the accumulated energization time even when the power is turned off.

  FIG. 2 shows the stored contents of the temporal luminance setting memory 5, in which the luminance setting value for the cumulative energization time is stored. TL indicates a predetermined lifetime. The characteristic of the cumulative energization time-luminance setting value shown in FIG. 2 compensates for the cumulative energization time-luminance characteristic shown in FIG. 7, and the luminance of the backlight lamp 3 is substantially constant regardless of the passage of time. It is set to be.

  Reference numeral 9 in FIG. 1 is an alarm display means. When the cumulative energization time reaches the life time TL shown in FIG. 2, an alarm signal from the microcomputer 1 indicates that the backlight lamp has reached the life time. An alarm is displayed.

  Reference numeral 10 denotes an external memory, which stores preset area correction coefficient and gradation correction coefficient data. FIG. 3 shows the contents stored in the external memory 10. The area correction coefficient is a correction coefficient for dividing the liquid crystal display screen into arbitrary areas and correcting the luminance stored for each area. In the example of FIG. 3, the horizontal direction of the liquid crystal display screen is divided into four parts X1 to X4, the vertical direction is divided into four parts Y1 to Y4, and correction coefficients D11 to D44 are stored in the respective divided areas. It has become. A gradation correction coefficient D45 is also stored. However, this is an example, and the present invention is not limited to this example.

Next, the area correction coefficients D11 to D44 related to luminance unevenness correction will be further described.
FIG. 4 is a characteristic diagram for explaining the concept of luminance unevenness correction. The horizontal axis represents the distance in the width direction of the display screen 45, and the vertical axis represents the luminance y of the display screen 45 corresponding to the distance x.

  A curve 26 in the characteristic graph of FIG. 4 shows the luminance characteristic of the cold cathode tube 41 itself before correction. The point indicated by A in the curve 26 indicates the darkest part of the liquid crystal display screen area. Reference numeral 27 denotes a reference luminance level indicating the desired brightness of the display screen. A curve 28 of the characteristic graph is a characteristic graph when the curve 26 of the characteristic graph is shifted upward so that the point A of the curve 26 of the characteristic graph matches the point B of the reference luminance level 27. Accordingly, the luminance of the curve 28 in the characteristic graph is all equal to or higher than the reference luminance level 27. In order to match point A to point B, the brightness of the backlight lamp is adjusted by the lamp brightness control circuit. For this reason, the luminance setting value is determined and stored in the temporal luminance setting memory 5 so that the point A matches the point B.

  A curve 29 in the characteristic graph indicates an area correction coefficient characteristic for correcting the luminance unevenness with display data. In the curve 29 of the characteristic graph, the area correction coefficient is set to 1 at the point B, and the luminance level is not changed. At the value exceeding the point B of the curve 28 of the characteristic graph, the area correction coefficient of the curve 29 of the characteristic graph is smaller than 1, and the value of the curve 28 of the characteristic graph is equal to the area correction coefficient of the curve 29 of the characteristic graph. The values are set so as to match the reference luminance level 27 when the values are multiplied. Reference numeral 30 denotes a corrected luminance characteristic after the value 28 is multiplied by the value of the curve 29 in the characteristic graph.

  That is, in this correction, the luminance unevenness (curve 26 of the characteristic graph) due to the light source is corrected by the luminance control of the backlight lamp (control to adjust the A point to the B point) and the brightness of the display data (curve 29 of the characteristic graph). Thus, the luminance characteristic of the light emitted from the surface of the liquid crystal display screen becomes the corrected luminance characteristic 30. As can be seen from FIG. 4, the corrected luminance characteristic 30 is a horizontal straight line characteristic that matches the reference luminance level 27, that is, a characteristic having no luminance unevenness.

  The characteristic of the curve 29 of the characteristic graph of FIG. 4 is shown for one of the vertical directions divided into a certain area, for example, Y1 of FIG. 3, but the vertical directions Y2, Y3, Y4 of the liquid crystal display screen. The area correction coefficients D11 to D44 are set in the same manner. The gradation correction coefficient D45 is set as a correction coefficient for correcting the average brightness of the entire display screen. Note that the area where the point A in FIG. 4 exists corresponds to the lowest luminance portion of the area divided by X1 to X4 and Y1 to Y4 in FIG.

  Reference numeral 11 denotes a gradation correction coefficient table (256 Bytes), which stores gradation correction coefficient data D45 from the video data 14 and the external memory 10 and stores them. Reference numeral 12 denotes an area correction coefficient table (256 Bytes), which stores area correction coefficient data D11 to D44 from the external memory 10 and stores them. The area correction coefficients D11 to D44 and the gradation correction coefficient D45 stored in the external memory 10 may be stored in the gradation correction coefficient table 11 and the area correction coefficient table 12 at the initial setting at the time of product shipment. The tone correction coefficient table 11 and the area correction coefficient table 12 constitute a reference table memory (LUT memory) 13.

  An arithmetic circuit 15 performs gradation correction, luminance correction, and color correction of video data and outputs the calculated correction data. The arithmetic circuit 15 receives the video data 14 and refers to the gradation correction coefficient data in the gradation correction coefficient table 11 and the area correction coefficient in the area correction coefficient table 12 when performing gradation correction and luminance correction. Therefore, the gradation correction coefficient table 11 and the area correction coefficient table 12 serve as a reference table memory (LUT memory) 13 for this calculation.

  Reference numeral 16 denotes a display data switching circuit, which generates display data based on video data from the video data 14, correction data from the arithmetic circuit 15, and display data switching signal 17 from the microcomputer 1, and outputs it to the liquid crystal display panel 4. .

  According to the present embodiment, a complicated control circuit using a luminance sensor is not necessary, and a luminance sensor that increases the number of parts is not necessary. Therefore, control is simple, and miniaturization and cost reduction are achieved. There is an effect that it is possible to provide a liquid crystal display device provided with a aging deterioration correction means. Further, according to the present invention, there is an effect that it is possible to provide a liquid crystal display device that can correct luminance unevenness for each area of the liquid crystal display screen.

(Second Embodiment)
FIG. 5 shows a control circuit configuration of a liquid crystal display device according to the second embodiment of the present invention.
Reference numeral 1 denotes a microcomputer (hereinafter referred to as a microcomputer) that controls the entire control circuit. Reference numeral 2 denotes a lamp brightness control circuit. Reference numeral 3 denotes a backlight lamp in which cold cathode tubes 41 are arranged as shown in FIG. Reference numeral 4 denotes a liquid crystal display panel for inputting display data and displaying video and characters.

  The microcomputer 1 inputs the luminance setting value 6 from the temporal luminance setting memory 5 and adjusts the luminance of the backlight lamp 3 by the lamp luminance control circuit 2. Since the luminance adjustment by the luminance setting value 6 cannot adjust the luminance unevenness, the entire brightness is adjusted.

  Reference numeral 7 denotes a cumulative energization time memory. A clock 8 outputs time data of the current time. The cumulative energization time memory 7 accumulates and stores the energization time of the liquid crystal display device based on the time data from the clock 8. The microcomputer 1 reads the accumulated energization time stored in the accumulated energization time memory 7 and reads the luminance data corresponding to the accumulated energization time in the time-dependent luminance setting memory 5. Thereby, the microcomputer 1 operates the lamp brightness control circuit 2 to adjust the brightness of the backlight lamp 3 based on the brightness setting value 6 so that the brightness of the backlight lamp 3 becomes substantially constant regardless of the passage of time.

  9 is an alarm display means, and when the cumulative energization time reaches the life time TL shown in FIG. 2, an alarm signal from the microcomputer 1 displays an alarm that the backlight lamp has reached the life time. ing.

  Reference numeral 19 denotes a time-dependent correction coefficient memory, and FIG. The temporal correction coefficient memory 19 stores a plurality of preset area correction coefficient data D11-1 to D44-1, D11-2 to D44-2,... D11-n to D44-n and gradation correction coefficients. Data D45-1 to D45-n are stored. In the external memory 10 in the first embodiment, one set of area correction coefficient data D11 to D44 and gradation correction coefficient data D45 are stored. In the present embodiment, the area correction coefficient and the gradation correction coefficient are stored. A plurality of sets of 1 to n are stored.

  The group of the area correction coefficient and the gradation correction coefficient stored in FIG. 6 is set at a predetermined time interval so as to compensate for the deterioration of the accumulated energization time-luminance characteristics for each area. That is, correction can be performed by changing the correction coefficient for each area so that luminance unevenness does not occur even if time elapses.

  Reference numeral 11 denotes a gradation correction coefficient table (256 Bytes), which is acquired by storing gradation correction coefficient data from the video data 14 and is read and set from the time-dependent correction coefficient memory 19 by the microcomputer 1 according to the accumulated energization time. Reference numeral 12 denotes an area correction coefficient table (256 Bytes), which is set by reading the area correction coefficient data from the time-dependent correction coefficient memory 19 by the microcomputer 1 according to the accumulated energization time. The tone correction coefficient table 11 and the area correction coefficient table 12 constitute a reference table memory (LUT memory) 13.

  An arithmetic circuit 15 performs gradation correction, luminance correction, and color correction of video data and outputs the calculated correction data. The arithmetic circuit 15 receives the video data 14 and refers to the gradation correction coefficient data in the gradation correction coefficient table 11 and the area correction coefficient in the area correction coefficient table 12 when performing gradation correction and luminance correction.

  Reference numeral 16 denotes a display data switching circuit, which generates display data based on video data from the video data 14, correction data from the arithmetic circuit 15, and display data switching signal 17 from the microcomputer 1, and outputs it to the liquid crystal display panel 4. .

According to the present embodiment, a complicated control circuit using a luminance sensor is not necessary, and a luminance sensor that increases the number of parts is not necessary. Therefore, control is simple, and miniaturization and cost reduction are achieved. There is an effect that it is possible to provide a liquid crystal display device provided with a aging deterioration correction means.
In addition, according to the present invention, it is possible to provide a liquid crystal display device that can correct the luminance unevenness for each area of the liquid crystal display screen and can also correct the temporal variation of the luminance unevenness.

Although the present invention has been described above with specific embodiments, the present invention is not limited to the U-shaped cold cathode tube, and other cold cathode tubes can be used. Further, the light source is not limited to a cold cathode tube, and may be a light source of another type that causes uneven brightness. For example, the present invention can be applied to a backlight system using an EL element, a light emitting diode, or the like.
Further, the present invention is not limited to those described in the above embodiment, and it goes without saying that the present invention can be modified and implemented within the scope of the gist of the present invention.

  The present invention can be widely used for correcting luminance unevenness of liquid crystal display screens of various video display devices such as televisions, personal computers, mobile terminals (PDA, mobile phone, etc.), and in-vehicle AV devices.

It is a figure which shows the control circuit structure of the liquid crystal display device by the 1st Embodiment of this invention. It is a figure explaining the memory content of the time-dependent luminance setting memory by this invention. It is a figure explaining the memory content of the external memory by this invention. It is a brightness | luminance characteristic view explaining the outline | summary of the brightness nonuniformity correction of this invention. It is a figure which shows the modification of the control circuit structure of the liquid crystal display device by the 2nd Embodiment of this invention. It is a figure explaining the memory content of the time-dependent correction coefficient memory by this invention. It is a figure which shows an example of the time-dependent deterioration characteristic of the lamp | ramp for backlights. It is a figure which shows an example of the lamp | ramp for backlight of a liquid crystal display device. It is a figure which shows an example of the brightness nonuniformity of a liquid crystal display device.

Explanation of symbols

1 ... Microcomputer
2 ... Lamp brightness control circuit 3 ... Backlight lamp 4 ... Liquid crystal display panel 5 ... Time-lapse brightness setting memory 6 ... Brightness set value 7 ... Cumulative energization time memory 8 ... Clock 9 ... Alarm display means 10 ... External memory 11 ... Gradation correction coefficient table 12 ... Area correction coefficient table 13 ... Reference table memory 14 ... Video data 15 ... Arithmetic circuit 16 ... Display data switching circuit 17 ... Switching signal 18 ... Display data 19 ... Temporal correction coefficient memory 26, 28, 29 ... Curve 27 of characteristic graph ... Reference luminance level 30 ... - corrected luminance characteristic 41 ... cold cathode tube 42 ... casing 43 ... driver 44 ... bent portion 45 ... display screen _{45 -1} ... driving unit 43 side _{45 -2} ·・ Bend 44 side

Claims (18)

In a liquid crystal display device that displays display data on the liquid crystal display panel, comprising a liquid crystal display panel and a backlight lamp that emits light from the back of the liquid crystal display panel.
Storage means for storing accumulated energization time obtained by accumulating energized time;
A liquid crystal display device comprising lamp luminance control means for adjusting the luminance of the backlight lamp to be the same based on the cumulative energization time. In a liquid crystal display device that displays display data on the liquid crystal display panel, comprising a liquid crystal display panel and a backlight lamp that emits light from the back of the liquid crystal display panel.
A cumulative energization time memory for storing a cumulative energization time obtained by accumulating the energized time;
A luminance setting memory that stores a luminance setting value that compensates for luminance deterioration of the backlight lamp with respect to the cumulative energization time and makes the luminance of the backlight lamp substantially constant;
Lamp brightness for reading the corresponding brightness setting value stored in the time-dependent brightness setting memory based on the accumulated power-on time stored in the cumulative power-on time memory and adjusting the brightness of the backlight lamp based on the read brightness setting value A liquid crystal display device comprising control means.   3. The liquid crystal display device according to claim 2, wherein the brightness setting value stored in the time-dependent brightness setting memory is set so that a lowest brightness area of the display screen has a predetermined brightness.   The liquid crystal display according to any one of claims 1 to 3, further comprising display data adjustment means for adjusting the luminance of a plurality of areas into which the liquid crystal display panel is divided to be substantially the same. apparatus.   The display data adjusting means has an area correction coefficient table storing area correction coefficients for each of the plurality of areas, and calculates correction data of display data with reference to the area correction coefficients stored in the area correction coefficient table. The liquid crystal display device according to claim 4.   The area correction coefficient is stored as a plurality of area correction coefficient tables corresponding to the cumulative energization time, and the display data correction data is calculated with reference to the area correction coefficient table corresponding to the cumulative energization time of the cumulative energization time memory. The liquid crystal display device according to claim 5. In a liquid crystal display device that displays display data on the liquid crystal display panel, comprising a liquid crystal display panel and a backlight lamp that emits light from the back of the liquid crystal display panel.
The accumulated energization time obtained by accumulating the energized time is stored, and the correction coefficient set for each area according to the accumulated energization time so that the luminance of the plurality of areas dividing the liquid crystal display panel is substantially the same. A liquid crystal display device comprising correction means for correcting by changing. In a liquid crystal display device that displays display data on the liquid crystal display panel, comprising a liquid crystal display panel and a backlight lamp that emits light from the back of the liquid crystal display panel.
An accumulated energization time memory for accumulating and storing energized time;
A time-dependent correction coefficient memory that stores a plurality of area correction coefficients corresponding to the cumulative energization time so that the luminance of a plurality of areas into which the liquid crystal display panel is divided is substantially the same,
An area correction coefficient table for storing the area correction coefficient corresponding to the accumulated energization time of the accumulated energization time memory;
A liquid crystal display device that calculates display data correction data with reference to the area correction coefficient stored in the area correction coefficient table.   9. The liquid crystal display device according to claim 1, further comprising alarm display means for displaying an alarm when the accumulated energization time reaches a predetermined life time. In a method for correcting deterioration over time of a liquid crystal display device that includes a backlight lamp that emits light from the back of the liquid crystal display panel and displays display data on the liquid crystal display panel.
Memorize the cumulative energization time that accumulated the energized time,
A method for correcting deterioration with time of a liquid crystal display device, wherein the backlight lamps are adjusted to have the same brightness based on the stored cumulative energization time. In a method for correcting deterioration over time of a liquid crystal display device that includes a backlight lamp that emits light from the back of the liquid crystal display panel and displays display data on the liquid crystal display panel.
Memorize the cumulative energization time that accumulated the energized time,
A luminance setting value that compensates for the luminance deterioration of the backlight lamp with respect to the cumulative energization time and makes the luminance of the backlight lamp substantially constant is stored in correspondence with the cumulative energization time,
A method for correcting deterioration with time of a liquid crystal display device, comprising: reading a luminance setting value corresponding to the stored cumulative energization time and adjusting a luminance of a backlight lamp based on the read luminance setting value.   12. The method for correcting deterioration with time of a liquid crystal display device according to claim 11, wherein the stored luminance setting value is set so that a lowest luminance area of the display screen has a predetermined luminance.   13. The adjustment according to claim 10, wherein in the area where the liquid crystal display panel is divided into a plurality of areas, the brightness of the plurality of areas is adjusted to be substantially the same. A method for correcting deterioration over time of a liquid crystal display device.   14. The method according to claim 13, wherein correction data of display data is calculated with reference to an area correction coefficient table storing area correction coefficients for each of the plurality of areas.   The area correction coefficient is stored as a plurality of area correction coefficient tables corresponding to the accumulated energization time, and the correction data of the display data is calculated with reference to the area correction coefficient table corresponding to the stored accumulated energization time. The method of correcting deterioration with time of a liquid crystal display device according to claim 14. In a method for correcting deterioration over time of a liquid crystal display device, comprising a backlight lamp for irradiating light from the back of the liquid crystal display panel and displaying display data on the liquid crystal display panel,
Memorize the cumulative energization time that accumulated the energized time,
A time-lapse of a liquid crystal display device, wherein correction is performed by changing a correction coefficient set for each area according to the accumulated energization time so that a plurality of areas divided from the liquid crystal display panel have substantially the same luminance. Degradation correction method. In a method for correcting deterioration over time of a liquid crystal display device, comprising a backlight lamp for irradiating light from the back of the liquid crystal display panel and displaying display data on the liquid crystal display panel,
Accumulate and store the energized time in the cumulative energization time memory,
A plurality of area correction coefficients for adjusting each area so that the luminance of a plurality of areas into which the liquid crystal display panel is divided are substantially the same are stored corresponding to the cumulative energization time,
A method for correcting deterioration with time of a liquid crystal display device, comprising: calculating correction data of display data with reference to the area correction coefficient corresponding to the cumulative energization time of the cumulative energization time memory.   18. The liquid crystal display device according to claim 10, further comprising an alarm display unit configured to display an alarm when the accumulated energization time reaches a predetermined life time. Correction method.

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