WO2013002200A1 - Liquid crystal display device - Google Patents

Abstract

Provided is a liquid crystal display device in which display quality can be enhanced even when temperature variations exist in the liquid crystal panel section thereof. A liquid crystal display device (200) has a liquid crystal panel section (10), a backlight unit (50) including a plurality of LEDs (22) and supplying light to the liquid crystal panel section (10), and a correction section (83) for correcting ghosting in the liquid crystal panel section (10). The correction section (83) varies the amount of ghosting correction for each predetermined region of the liquid crystal panel section (10) in accordance with the temperature distribution of the liquid crystal panel section (10) due to heat from the plurality of LEDs (22).

Description

Liquid crystal display

This invention relates to a liquid crystal display device having a liquid crystal panel.

The liquid crystal display device includes a liquid crystal panel unit and an illumination unit (backlight). The liquid crystal panel unit displays an image (image), and the illumination unit supplies light to the liquid crystal panel unit. It is known that a ghost occurs in a liquid crystal display device. A ghost is a phenomenon in which a video signal is displayed shifted by one line from a position (line) where the video signal is to be displayed.

Therefore, it has been proposed to correct the ghost (for example, Japanese Patent Application Laid-Open No. 2003-150131).

In this conventional technique, the liquid crystal display device includes a ghost correction unit. The ghost correction unit changes the correction coefficient according to the luminance level difference between the front and rear lines. Ghosts are corrected appropriately.

In recent years, a light emitting diode (LED) is used as a light source of an illumination unit (backlight). In such an illumination unit, temperature unevenness occurs depending on the arrangement of the light source and the like. In this case, the temperature distribution in the liquid crystal panel is not uniform.

However, with the conventional technology, it is difficult to properly correct the ghost when the temperature distribution of the liquid crystal panel is not uniform. Therefore, the display quality of the liquid crystal display device is lowered.

In order to solve the above problems, one of the objects of the present invention is to provide a liquid crystal display device capable of improving the display quality even when the temperature distribution of the liquid crystal panel portion is non-uniform.

Therefore, the liquid crystal display device of the present invention includes a liquid crystal panel unit, an illumination unit that includes a plurality of light sources and supplies light to the liquid crystal panel unit, and a correction unit that performs ghost correction of the liquid crystal panel unit. The correction unit changes the ghost correction amount for each predetermined region of the liquid crystal panel unit according to the heat distribution of the liquid crystal panel unit.

In this liquid crystal display device, the ghost is appropriately corrected (reduced) according to the heat distribution of the liquid crystal panel. Therefore, even if the heat distribution of the liquid crystal panel portion is non-uniform, the display quality can be improved.

Preferably, the liquid crystal panel unit includes a first region and a second region having a temperature lower than that of the first region, and the ghost correction amount in the first region is smaller than the ghost correction amount in the second region. In this case, the response characteristics of the liquid crystal panel unit can be controlled so as to be substantially constant throughout the liquid crystal panel unit. Therefore, the ghost can be effectively corrected (reduced).

Also preferably, the correction unit has a plurality of parameter tables that define a voltage corresponding to a ghost correction amount by comparing the luminance of a predetermined line and the luminance of the next line in the liquid crystal panel unit. In this case, the ghost correction amount can be easily changed for each predetermined region of the liquid crystal panel unit according to the heat distribution of the liquid crystal panel unit.

The parameter table is preferably provided for each temperature region of the liquid crystal panel. The ghost can be corrected (reduced) with an appropriate ghost correction amount for each temperature region of the liquid crystal panel. Further, it is more preferable that the parameter table is provided for each temperature in addition to each temperature region of the liquid crystal panel unit. The ghost correction amount can be changed according to the temperature in a predetermined region of the liquid crystal panel unit. That is, the ghost correction amount can be changed according to the temperature change of the liquid crystal panel unit.

The liquid crystal display device preferably further includes temperature measuring means for measuring the temperature of the liquid crystal panel unit. Information such as the temperature distribution or temperature change of the liquid crystal panel can be obtained by the temperature measuring means. By using the obtained information, the ghost correction amount can be changed more accurately according to the heat distribution of the liquid crystal panel unit.

The illumination unit includes, for example, a light guide member that guides light from the light source, and a plurality of light sources are arranged at the end of the light guide member. In this case, the illumination unit is an edge light (side light) type, and the illumination unit and the liquid crystal display device can be easily reduced in thickness.

Although it is easy to reduce the thickness of the edge light type illumination unit, a plurality of light sources are disposed at the end of the light guide member, and the temperature in the vicinity of the end of the light guide member tends to increase. For this reason, in a liquid crystal display device including an edge light type illumination unit, the temperature distribution of the liquid crystal panel unit tends to be non-uniform.

However, in this liquid crystal display device, as described above, display quality can be improved even when the temperature distribution of the liquid crystal panel portion is non-uniform. Therefore, by using an edge light type illumination unit, it is possible to reduce the thickness of the liquid crystal display device while improving display quality.

The lighting part may be a direct type. Specifically, the illumination unit may be disposed so as to overlap the liquid crystal panel unit, and a plurality of light sources may be disposed immediately below the liquid crystal panel unit. In this case, it is preferable that the plurality of light sources are driven independently of each other. So-called dimming control for each area (local dimming control, area active control, etc.) that adjusts the brightness of each area of the illumination unit in synchronization with the brightness of each area of the display image can be realized. Thereby, the contrast of the liquid crystal display device can be greatly improved and the power consumption can be reduced.

In the case of such a direct illumination unit, the temperature is higher in the high luminance region than in the low luminance region. For this reason, the temperature distribution of the liquid crystal panel portion becomes non-uniform.

However, as described above, this crystal display device can improve the display quality even when the temperature distribution of the liquid crystal panel is non-uniform. Therefore, by using a direct illumination unit, it is possible to reduce power consumption while further improving display quality.

The multiple light sources may be arranged unevenly. For example, light sources may be densely arranged in the end region of the illumination unit as compared to other regions. In this case, the number of light sources arranged in the end area of the illumination unit is larger than the number of light sources arranged in other areas. Although the end region tends to be dark, the end region can be brightened.

According to the present invention, it is possible to easily obtain a liquid crystal display device capable of improving display quality even when the temperature distribution of the liquid crystal panel portion is non-uniform.

It is a disassembled perspective view of the liquid crystal display device of 1st Embodiment of this invention. It is sectional drawing which showed typically the liquid crystal display device of 1st Embodiment of this invention. It is the figure which showed typically the temperature distribution of the display panel part of the liquid crystal display device of 1st Embodiment of this invention. It is the top view which showed typically the liquid crystal display device of 1st Embodiment of this invention. It is the block diagram which showed the structure of the liquid crystal display device of 1st Embodiment of this invention. It is the block diagram which showed the structure of the liquid crystal display device of 1st Embodiment of this invention. It is the top view (figure for demonstrating a ghost) which showed the liquid crystal panel part of the liquid crystal display device of 1st Embodiment of this invention. It is a timing chart for demonstrating appearance of a ghost in case the temperature of a liquid crystal panel part is normal temperature. It is a timing chart for explaining appearance of a ghost when the temperature of a liquid crystal panel is high. It is a timing chart for demonstrating appearance of a ghost in case the temperature of a liquid crystal panel part is low. It is the figure which showed an example of the ghost correction | amendment in the area | region near the center of the liquid crystal panel part of 1st Embodiment of this invention. It is the figure which showed an example of the ghost correction | amendment in the area | region of the both ends vicinity of the liquid crystal panel part of 1st Embodiment of this invention. It is sectional drawing which showed typically the liquid crystal display device of 2nd Embodiment of this invention. It is the top view which showed typically the liquid crystal display device of 2nd Embodiment of this invention. It is the block diagram which showed schematic structure of the liquid crystal display device of 2nd Embodiment of this invention. It is the top view which showed typically the liquid crystal display device of 3rd Embodiment of this invention. It is the top view which showed typically the liquid crystal display device of 3rd Embodiment of this invention. It is the block diagram which showed schematic structure of the liquid crystal display device of 3rd Embodiment of this invention. It is the top view which showed typically the liquid crystal display device of the modification of 1st Embodiment. It is the top view which showed typically the liquid crystal display device of the modification of 2nd Embodiment.

DETAILED DESCRIPTION Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings.

(First embodiment)
A liquid crystal display device 200 according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an exploded perspective view of the liquid crystal display device 200. FIG. 2A is a cross-sectional view schematically showing the liquid crystal display device 200. FIG. 2B is a diagram schematically illustrating the temperature distribution of the display panel unit of the liquid crystal display device 200. FIG. 3 is a plan view schematically showing the liquid crystal display device 200. 4 to 11 are diagrams for explaining the liquid crystal display device 200. FIG.

As shown in FIG. 1, the liquid crystal display device 200 according to the first embodiment includes a liquid crystal panel unit 10, a backlight unit 50, and a pair of housings 70 (a front housing 71 and a back housing 72). The backlight unit 50 supplies light to the liquid crystal panel unit 10. The pair of housings 70 sandwich the liquid crystal panel unit 10 and the backlight unit 50.

The liquid crystal panel unit 10 includes an active matrix substrate 11 and a counter substrate 12 facing the active matrix substrate 11. The active matrix substrate 11 includes, for example, a TFT (Thin Film Transistor) as a switching element. The active matrix substrate 11 and the counter substrate 12 are bonded together with a sealing material (not shown). Liquid crystal (not shown) is injected into the gap between the active matrix substrate 11 and the counter substrate 12. Polarizing films 13 are attached to the light-receiving surface side of the active matrix substrate 11 and the light-emitting surface side of the counter substrate 12, respectively.

The liquid crystal panel unit 10 displays an image using a change in transmittance caused by the inclination of liquid crystal molecules.

In the first embodiment, the backlight unit 50 is an edge light (side light) type backlight unit, and includes an LED module 20, a light guide (light guide member) 30 that guides light from the LED module 20, A reflection sheet (reflection member) 41, a backlight chassis 42, a diffusion plate (diffusion member) 43, a prism sheet 44, and a lens sheet 45 are included. As shown in FIGS. 1 and 2A, the backlight unit 50 is disposed directly below the liquid crystal panel unit 10.

The LED module 20 includes an LED 22 as a light source and a mounting substrate 21. The LED 22 is mounted on the mounting substrate 21.

The mounting substrate 21 is a plate-shaped and rectangular substrate. A plurality of electrodes (not shown) are arranged on the mounting surface 21 a of the mounting substrate 21. The LED 22 is mounted on these electrodes.

LED 22 emits light while receiving current. A plurality of LEDs 22 are arranged on the mounting substrate 21 with a predetermined interval. The LED 22 is disposed in the vicinity of the side surface 31 of the light guide 30.

The light guide 30 is made of, for example, a transparent resin material such as acrylic or polycarbonate, and is formed on a single light guide plate as shown in FIGS. The light guide 30 is formed in a substantially rectangular shape (substantially rectangular shape) when seen in a plan view. The light guide 30 has an upper surface 30U (see FIG. 1), a lower surface 30B (see FIG. 1) which is the opposite surface, and four side surfaces 31 (31a to 31d). The side surfaces 31a and 31b are incident surfaces 32 on which light from the LED 22 is incident. That is, the light from the LED 22 enters the light guide 30 through the side surfaces 31 (31a and 1b).

The side surfaces 31 a and 31 b of the light guide 30 are surfaces that face in opposite directions and are parallel to the longitudinal direction (X direction) of the light guide 30. The side surfaces 31 c and 31 d of the light guide 30 are surfaces that face in opposite directions and are parallel to the short direction (Y direction) of the light guide 30.

The LED module 20 on which the plurality of LEDs 22 are mounted is disposed on both sides of the backlight unit 50 in the left-right direction (X direction). That is, the LED module 20 is disposed so that the light emitting surface of the LED 22 faces the side surface 31a, and the LED module 20 is disposed so that the light emitting surface of the LED 22 faces the side end surface 31b.

The light incident from the incident surface 32 (side surfaces 31a and 31b) is guided through the light guide 30 and emitted from the upper surface 30U as planar light (emitted light). The upper surface 30U is a light emitting surface 30U that emits light toward the outside (the liquid crystal panel unit 10).

1 and 2A, the reflection surface 41U (see FIG. 1) of the reflection sheet 41 faces the lower surface 30B of the light guide 30. As shown in FIG. The reflective heat 41 reflects the light leaked from the lower surface 30B so as to return it to the light guide 30, thereby preventing light loss.

The backlight chassis 42 (FIG. 1) is, for example, a box-shaped member. The backlight chassis 42 has a bottom surface 42 </ b> B and houses the LED module 20, the light guide 30 and the reflection sheet 41.

The diffusion plate 43 is an optical sheet that overlaps the light guide 30 and diffuses light from the light guide 30. That is, the diffusion plate 43 diffuses the light from the light guide 30 and spreads the light over the entire area of the liquid crystal panel unit 10.

The prism sheet 44 is an optical sheet that overlaps the diffusion plate 43. The prism sheet 44 includes, for example, triangular prisms extending in one direction (linear shape) arranged in parallel, and deflects the radiation characteristics of light from the diffusion plate 43.

The lens sheet 45 is an optical sheet that overlaps the prism sheet 44. Fine particles that refract and scatter light are dispersed inside the lens sheet 45. The lens sheet 45 does not locally collect the light from the prism sheet 44. That is, the lens sheet 45 suppresses the difference in brightness (light intensity unevenness).

In the backlight unit 50, the light from the LED module 20 is emitted as planar light by the light guide 30, and the light from the light guide 30 passes through the plurality of optical sheets 43 to 45, and the liquid crystal panel unit. 10 is supplied. The non-light emitting liquid crystal panel unit 10 receives light (backlight light) from the backlight unit 50 and improves the display function.

In the first embodiment, as shown in FIG. 4, the liquid crystal display device 200 further includes a display control unit 80, a liquid crystal driver 90, and an LED driving unit 51. The liquid crystal driver 90 includes a source driver 91 and a gate driver 92. The LED driving unit 51 drives the backlight unit 50 (LED 22). As shown in FIG. 5, the liquid crystal panel unit 110 includes a liquid crystal driver 90 and a liquid crystal panel unit 10.

As shown in FIG. 4, the liquid crystal panel unit 10 includes a plurality of source bus lines 91a, a plurality of gate bus lines 92a, and a plurality of pixel formation units (not shown). The plurality of pixel formation portions are provided corresponding to the intersections of the source bus line 91a and the gate bus line 92a, respectively. These pixel forming portions are arranged in a matrix to form a pixel array. Each pixel formation unit includes the above-described TFT (not shown), pixel electrode (not shown), common electrode (not shown), and liquid crystal layer (not shown). The common electrode is a counter electrode provided in common to the plurality of pixel formation portions. The liquid crystal layer is sandwiched between the pixel electrode and the common electrode. The gate terminal of the TFT is connected to the gate bus line 92a, and the source terminal of the TFT is connected to the source bus line 91a. The drain terminal of the TFT is connected to the pixel electrode.

The display control unit 80 receives the image signal DAT and the timing signal group TG, as well as the video signal DV, the source start pulse signal SSP, the source clock signal SCK, the latch strobe signal LS, the gate start pulse signal GSP, the gate clock signal GCK, the luminance The signal KS is output.

The image signal DAT is sent from the outside. The timing signal group TG is a horizontal synchronization signal, a vertical synchronization signal, or the like. The source start pulse signal SSP, the source clock signal SCK, the latch strobe signal LS, the gate start pulse signal GSP, and the gate clock signal GCK control image display in the liquid crystal panel unit 10. The luminance signal KS controls the luminance of the backlight unit 50.

As shown in FIG. 5, the display control unit 80 includes a liquid crystal controller unit 81 that controls the display of the liquid crystal panel unit 10. The liquid crystal controller unit 81 includes a drive voltage value determination unit 82 and a correction unit 83. The correction unit 83 includes a ghost voltage value determination unit 84 and a memory 86 and performs ghost correction of the liquid crystal panel unit 10. The memory 86 has a ghost parameter reference table (parameter table) 85.

The drive voltage value determination unit 82 determines a drive voltage value for driving the liquid crystal panel unit 10 from the LCD data signal output from the signal generation unit 80d. The ghost voltage value determination unit 84 determines the ghost correction amount by referring to the ghost parameter reference table 85, and adds the ghost correction amount to the drive voltage value (or subtracts the ghost correction amount from the drive voltage value). A voltage in consideration of the ghost correction amount is applied to the liquid crystal driver 90.

The display control unit 80 further includes a color restoration unit 80a, a contrast adjustment unit 80b, a gamma correction unit 80c, a signal generation unit 80d, and the like. The color recovery unit 80a recovers the signal transmitted from the image data acquisition unit 120 into red (R), green (G), and blue (B) color signals, and outputs them to the contrast adjustment unit 80b. The contrast adjustment unit 80b performs contrast adjustment on the signal from the color restoration unit 80a and outputs the signal to the gamma correction unit 80c. The gamma correction unit 80c performs gamma correction on the signal from the contrast adjustment unit 80b and outputs the signal to the signal generation unit 80d. The signal generation unit 80d generates various signals (see FIG. 4) such as a gate clock signal GCK and a latch strobe signal LS. An LCD data signal is output from the signal generator 80d to the drive voltage value determiner 82. When the signal from the image data acquisition unit 120 is a composite signal, the display control unit 80 includes other units such as a Y / C separation unit and a signal adjustment unit.

As shown in FIG. 4, the source driver 91 receives the video signal DV, the source start pulse signal SSP, the source clock signal SCK, and the latch strobe signal LS, and applies a driving video signal to each source bus line 91a. Based on the gate start pulse signal GSP and the gate clock signal GCK, the gate driver 92 repeats the application of the active scanning signal to each gate bus line 92a with one vertical scanning period as a cycle. The LED drive unit 51 receives the luminance signal KS and drives the backlight unit 50 (LED 22).

As described above, a driving video signal is applied to each source bus line 91a, a scanning signal is applied to each gate bus line 92a, light is irradiated from the back side of the liquid crystal panel unit 10, and an image (video) is liquid crystal. Displayed on the panel unit 10.

In the drive timing setting of the liquid crystal display device, the timing of the gate clock signal GCK and the latch strobe signal LS is specified so that no ghost appears. The gate clock signal GCK is a signal that determines the timing of the gate driver 92, and the latch strobe signal LS is a signal that determines the timing of the source driver 91. When the ghost cannot be sufficiently corrected in the state defined as described above, the ghost correction is performed by the correction unit 83.

However, the liquid crystal has temperature characteristics, and the movement of the liquid crystal (liquid crystal layer) of the liquid crystal panel unit 10 varies depending on the temperature. The rising and falling characteristics of the source voltage (voltage applied to the liquid crystal layer) are affected by the ambient temperature. The waveform becomes dull at low temperatures. As a result, a ghost (post-ghost) that could not be seen at room temperature may appear.

In the edge light type backlight unit 50, the LEDs 22 as light sources are concentrated on the end of the liquid crystal panel unit 10 (near the side surface of the light guide 30). Therefore, the heat distribution of the liquid crystal panel unit 10 tends to be biased. For this reason, the dullness of the waveform such as the source waveform (the waveform of the voltage applied to the liquid crystal layer) and the gate waveform is not constant over the entire liquid crystal panel unit 10 (the entire surface), and the strength of the appearing ghost is also nonuniform. Therefore, in the conventional ghost correction in which the correction amount for the ghost is constant throughout the liquid crystal panel unit 10 (constant for each gradation), the display quality is deteriorated.

Note that “ghost” is a phenomenon in which the video signal is displayed shifted by one line from the position (line) to be displayed. A “ghost” includes a front ghost and a back ghost. The “front ghost” is a phenomenon that is displayed one line before the target, and the “rear ghost” is a phenomenon that is displayed one line behind the target (a position advanced one line in the scanning direction). Specifically, for example, as shown in FIG. 6, the phenomenon that the voltage written to the n + 1th row (n + 1 line) is applied to the nth row (nline) is the pre-ghost, and the nth row (nline). The phenomenon that the voltage to be written to the (n + 1) th line (n + 1 line) is applied to the rear ghost.

The appearance of a ghost due to the temperature of the liquid crystal panel will be described with reference to FIGS. FIG. 7 shows the case where the temperature of the liquid crystal panel is normal. As shown in FIG. 7, in synchronization with the rising edge of the gate clock signal GCK, the Nth gate Gout_n goes high (H) and the Nth gate opens (Nth gate OPEN). In synchronization with the rising edge of the latch strobe signal LS, the Nth source Sout_n (voltage applied to the liquid crystal layer) goes high, and the voltage is written in the nth row (nline). The Nth gate Gout_n becomes low (L) in synchronization with the rising edge of the next gate clock signal GCK, and the (N + 1) th gate Gout_n + 1 becomes high in synchronization with the rising edge of the gate clock signal GCK. . Then, the (N + 1) th gate Gout_n + 1 is opened (N + 1th gate OPEN). Similarly, the N-th source Sout_n then goes low in synchronization with the rising edge of the latch strobe signal LS, and in synchronization with the rising edge of the latch strobe signal LS, the N + 1-th source Sout_n + 1 (in the liquid crystal layer). Applied voltage) goes high. Then, a voltage is written in the (n + 1) th row (n + 1 line).

Since the (N + 1) th gate Gout_n + 1 is opened before the Nth source Sout_n is closed, the voltage of the Nth source Sout_n is written to the (N + 1) th (n + 1th row). Specifically, a voltage corresponding to the region q (hatched portion) in the Nth source Sout_n is written in the (N + 1) th (n + 1th row). When this region q becomes large, a rear ghost is likely to appear. On the other hand, since the (N + 1) th source Sout_n + 1 is opened before the Nth gate Gout_n is closed (becomes a low state), the voltage corresponding to the region r (hatched portion) in the (N + 1) th source Sout_n + 1 is Nth (nth row). ). When this region r becomes large, a front ghost is likely to appear. Note that, as described above, the timings of the gate clock signal GCK and the latch strobe signal LS are adjusted so as to balance the amounts of the front ghost and the rear ghost and make both inconspicuous.

When the temperature of the liquid crystal panel is lowered due to a change in the ambient temperature, the waveform becomes dull as shown in FIG. In particular, due to the influence of the waveform (Sout) of the source (voltage applied to the liquid crystal layer) having a large dullness, the amount of the front ghost and the rear ghost is changed. Specifically, the waveform becomes dull at low temperatures, and a post-ghost is likely to occur (the area of the region r in the source Sout_n + 1 is reduced, and the area of the region q in the source Sout_n is increased).

On the contrary, when the temperature of the liquid crystal panel increases, the rising and falling of the waveform become agile, as shown in FIG. 9, and a front ghost is likely to occur (the area of the region r in the source Sout_n + 1 increases, The area of the region q in Sout_n is reduced).

As described above, in the edge light type backlight unit 50, the heat distribution of the liquid crystal panel unit 10 is likely to be biased.

For example, as shown in FIGS. 2 and 3, the temperature of the liquid crystal panel unit 10 is high in the region (region Ar1) near the LED 22, and the liquid crystal panel unit 10 is in a region (region Ar2) away from the LED 22 by a predetermined distance. Is relatively low (the temperature of the liquid crystal panel is lower than that in the vicinity of the LED 22 (region Ar1)). That is, in the liquid crystal display device 200 including the edge light type backlight unit 50, the temperature is high near the light source of the liquid crystal panel unit 10, and the temperature is relatively low near the center of the liquid crystal panel unit 10. Waveform dullness is large near the center of the liquid crystal panel unit 10 having a low temperature, and waveform dullness is small near both ends of the liquid crystal panel unit 10 having a high temperature.

Therefore, in the first embodiment, the correction unit 83 changes the ghost correction amount for each predetermined region of the liquid crystal panel unit 10.

More specifically, for example, in the vicinity of the light source where the liquid crystal panel unit 10 is high (area Ar1), the parameter is set to be weak (ghost correction amount is small). On the other hand, in the vicinity of the center of the panel where the liquid crystal panel unit 10 is relatively low (area Ar2), the parameter is set to be strong (ghost correction amount is large). Thereby, even when the temperature distribution of the liquid crystal panel unit 10 is not uniform, it is possible to control the ghost characteristics to be substantially constant over the entire liquid crystal panel unit.

The ghost correction amount is determined by comparing the luminance of a predetermined line in the liquid crystal panel unit 10 with the luminance of the next line. As shown in FIGS. 10 and 11, for example, when the luminance of the previous line is lower than the luminance of the next line, a high voltage is applied to the next line to prevent this luminance from appearing as a ghost. At that time, in the area Ar2 near the center of the liquid crystal panel portion, a rear ghost is likely to appear, so that ghost correction is applied strongly as shown in FIG. On the other hand, in the area Ar1 in the vicinity of both ends (near the light source) of the liquid crystal panel portion, the ghost is unlikely to appear, so that ghost correction is applied weakly as shown in FIG.

Note that by adjusting the timings of the gate clock signal GCK and the latch strobe signal LS, the previous ghost is set so as not to appear even when the temperature distribution occurs (when the temperature distribution is non-uniform).

As shown in FIG. 2B, the boundary g between the region Ar1 and the region Ar2 in the liquid crystal panel unit 10 is, for example, in a region (region R) having a large temperature gradient. The boundary g is easily set by measuring the temperature distribution.

As shown in FIG. 3, the distance between the boundary g and the end of the liquid crystal panel unit 10 in the X direction is L. For example, in the case of a 40-inch liquid crystal panel unit, the distance L is, for example, about 3 cm (about 3.4% with respect to the panel length (about 88.5 cm)). However, the distance L varies depending on the number of LEDs 22, the thermal efficiency, the temperature of the liquid crystal panel unit 10, and the like.

As described above, the ghost correction amount is determined by the correction unit 83 by comparing the luminance of the predetermined line in the liquid crystal panel unit 10 with the luminance of the next line. As shown in FIG. 5, the correction unit 83 includes a ghost parameter reference table 85 (lookup table). The correction unit 83 refers to the ghost parameter reference table 85 to determine a ghost correction amount (ghost parameter) for each luminance difference (gradation).

The ghost parameter reference table 85 includes at least a table for the area Ar1 and a table 85 for the area Ar2. The table for the area Ar1 is a table (table for setting parameters weakly) assuming that the liquid crystal panel unit 10 becomes high temperature. On the other hand, the table for the area Ar2 is a table (a table in which parameters are set to be stronger) assuming that the liquid crystal panel unit 10 has a relatively low temperature. Each setting value of the ghost parameter reference table 85 is determined by the temperature, gradation, input signal frequency, and the like.

In the first embodiment, as described above, even when the temperature distribution of the liquid crystal panel unit 10 is not uniform, the ghost can be corrected (reduced) appropriately. Therefore, the display quality of the liquid crystal display device 200 can be improved.

The ghost correction amount in the region Ar1 near both ends (near the light source) of the liquid crystal panel unit 10 is smaller than the ghost correction amount in the region Ar2 near the center of the liquid crystal panel unit 10. In such a configuration, the response characteristics of the liquid crystal panel unit 10 can be controlled so as to be substantially constant throughout the liquid crystal panel unit 10. Therefore, the ghost can be effectively corrected (reduced).

The correcting unit 83 determines the ghost correction amount (ghost parameter) by comparing the luminance of a predetermined line with the luminance of the next line in the liquid crystal panel unit 10. The correction unit 83 includes a ghost parameter reference table 85 that defines a ghost correction amount for a luminance difference, and the ghost correction amount can be easily determined by referring to the ghost parameter reference table 85.

The ghost parameter reference table 85 includes a table for each temperature region (for each region Ar1 and each region Ar2) of the liquid crystal panel unit 10. Therefore, the ghost can be corrected (reduced) appropriately for each temperature region of the liquid crystal panel unit 10.

In the first embodiment, the liquid crystal display device 200 includes an edge light type backlight unit 50. Therefore, the liquid crystal display device 200 can be easily reduced in thickness.

In the liquid crystal display device 200 including the edge light type backlight unit 50, the temperature distribution of the liquid crystal panel unit 10 tends to be non-uniform. However, as described above, the display quality can be improved even if the temperature distribution of the liquid crystal panel unit 10 is not uniform. Therefore, it is possible to reduce the thickness of the liquid crystal display device 200 while improving display quality.

(Second embodiment)
Next, a liquid crystal display device 200a according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 12 is a cross-sectional view schematically showing the liquid crystal display device 200a. FIG. 13 is a plan view schematically showing the liquid crystal display device 200a. FIG. 14 is a block diagram showing a schematic configuration of the liquid crystal display device 200a. In addition, in each figure, the same code | symbol is attached | subjected to a corresponding component, and the overlapping description is abbreviate | omitted suitably.

Unlike the first embodiment, the liquid crystal display device 200a of the second embodiment includes a direct-type backlight unit 150. Specifically, as shown in FIG. 12, in the backlight unit 150, the LED module 20 (LED 22) is disposed on the bottom surface 42 </ b> B of the backlight chassis 42. As shown in FIGS. 12 and 13, the backlight unit 150 is disposed so as to overlap the liquid crystal panel unit 10, and the plurality of LEDs 22 are disposed immediately below the liquid crystal panel unit 10.

As shown in FIG. 13, in the second embodiment, the plurality of LEDs 22 are arranged at equal intervals. The plurality of LEDs 22 can be controlled independently of each other. Therefore, it is possible to perform so-called dimming control for each area (local dimming control, area active control, etc.) that adjusts the brightness of each area of the backlight unit 150 in synchronization with the brightness of each area of the display image. .

When the light source (LED 22) is turned off or when the luminance of the light source is low, the temperature of the region of the liquid crystal panel unit 10 corresponding to the light source is relatively low. On the other hand, when the light source (LED 22) is turned on or when the luminance of the light source is high, the temperature of the region of the liquid crystal panel unit 10 corresponding to the light source becomes high. Therefore, in the liquid crystal display device 200a including such a backlight unit 150, the heat distribution of the liquid crystal panel unit 10 may be biased.

Therefore, in the second embodiment, the ghost correction amount is changed for each predetermined area of the liquid crystal panel unit 10 as in the first embodiment. Specifically, for example, in a region where the light source (LED 22) is turned off and the temperature is low, a rear ghost is likely to appear, and as shown in FIG. On the other hand, for example, in a region where the light source (LED 22) is lit and the temperature is high, a rear ghost hardly appears, and ghost correction is applied weakly as shown in FIG.

As shown in FIG. 14, in the second embodiment, the LED drive unit 51 and the correction unit 83 work together to select an optimum ghost parameter. The LED driving unit 51 includes an LED driver 51a and a counter 51b that control driving of the LEDs 22 of the backlight unit 150. The counter 51b is connected to the LED driver 51a and counts a predetermined time. The LED driver 51 a is connected to the ghost voltage value determination unit 84 of the correction unit 83. The LED driver 51a calculates the integrated value of the current applied to each LED 22 for a predetermined time. The ghost voltage value determination unit 84 calculates the temperature of the liquid crystal panel unit 10 based on the integrated value of the current applied to each LED 22. The correction unit 83 determines an optimum ghost correction amount for each predetermined region (for each temperature region) of the liquid crystal panel unit 10 from the ghost parameter reference table 85.

The ghost parameter reference table 85 has a plurality of tables for each temperature region or for each temperature. Other configurations of the second embodiment are the same as those of the first embodiment.

In the second embodiment, as described above, the liquid crystal display device 200a includes the direct-type backlight unit 150 and can perform dimming control for each region (local dimming control, area active control, etc.). Thereby, the contrast of the liquid crystal display device can be greatly improved and the power consumption can be reduced.

In the case of the direct backlight unit 150, the temperature is higher in the high luminance area than in the low luminance area. Therefore, also in the liquid crystal display device 200a including the direct type backlight unit 150, the temperature distribution of the liquid crystal panel unit 10 becomes non-uniform.

However, even in the liquid crystal display device 200a of the second embodiment, the display quality can be improved even when the temperature distribution of the liquid crystal panel unit 10 is not uniform as described above. Therefore, it is possible to reduce power consumption while further improving display quality.

If the ghost parameter reference table 85 includes a table for each temperature, the ghost correction amount can be changed according to the temperature change of the liquid crystal panel unit 10. Other effects of the second embodiment are the same as those of the first embodiment.

(Third embodiment)
A liquid crystal display device 200b according to a third embodiment of the present invention will be described with reference to FIGS. 15 and 16 are plan views schematically showing the liquid crystal display device 200b. FIG. 17 is a block diagram showing a schematic configuration of the liquid crystal display device 200b. FIG. 15 shows an example of the third embodiment, and FIG. 16 shows another example of the third embodiment. In addition, in each figure, the same code | symbol is attached | subjected to a corresponding component, and the overlapping description is abbreviate | omitted suitably.

The liquid crystal display device 200b of 3rd Embodiment contains the temperature sensor 60 which measures the temperature of the liquid crystal panel part 10, as shown in FIG.15 and FIG.16. For example, as shown in FIG. 15, the temperature sensor 60 may measure (temperature measurement) one location of the liquid crystal panel unit 10. As shown in FIG. 16, the plurality of temperature sensors 60 may measure (temperature measurement) a plurality of locations on the liquid crystal panel unit 10. In FIG.15 and FIG.16, the area | region enclosed with the dashed-two dotted line s shows a measurement location.

As shown in FIG. 15, when measuring one location of the liquid crystal panel unit 10, by measuring the temperature correspondence between the actual measurement location and other locations in advance at each temperature, The temperature at multiple locations can be recognized by measurement. Therefore, if comprised in this way, the temperature distribution of the liquid crystal panel part 10 can be measured in real time.

On the other hand, as shown in FIG. 16, when measuring a plurality of locations of the liquid crystal panel unit 10 with a plurality of temperature sensors 60 (temperature measurement), the temperature distribution of the liquid crystal panel unit 10 can be measured more accurately in real time.

As shown in FIG. 17, the temperature sensor 60 is connected to the ghost voltage value determination unit 84 of the correction unit 83, and outputs the measured temperature to the ghost voltage value determination unit 84. Based on the temperature data from the temperature sensor 60, the ghost voltage value determination unit 84 determines an optimum ghost correction amount for each predetermined region (for each temperature region) of the liquid crystal panel unit 10 from the ghost parameter reference table 85. .

The ghost parameter reference table 85 has a plurality of tables for each temperature in addition to each temperature region. Therefore, a more optimal ghost correction amount is determined according to the temperature change of the liquid crystal panel unit 10. Other configurations of the third embodiment are the same as those of the first or second embodiment.

In the third embodiment, the temperature sensor 60 can obtain information such as the temperature distribution or temperature change of the liquid crystal panel unit 10. Therefore, by using the obtained information, the ghost correction amount can be changed more accurately according to the heat distribution of the liquid crystal panel unit 10.

The temperature of the liquid crystal panel unit 10 varies depending on a change in ambient temperature (environmental temperature) or an elapsed time after the power is turned on. More optimal ghost correction can be performed by changing the ghost correction amount for each predetermined region in accordance with the temperature change. Thereby, display quality can be improved more.

The ghost parameter reference table 85 has a plurality of tables for each temperature in addition to each temperature region of the liquid crystal panel unit 10. Therefore, the ghost correction amount can be changed according to the temperature change of the liquid crystal panel unit 10. Other effects of the third embodiment are the same as those of the first or second embodiment.

In addition, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes meanings equivalent to the scope of claims for patent and all modifications within the scope.

For example, in the first to third embodiments, the backlight unit includes a diffusion plate, a prism sheet, and a lens sheet as optical members (optical sheets). However, the optical member (optical sheet) may be appropriately changed, added, or reduced as necessary.

In the first to third embodiments, the ghost correction amount is changed according to the heat distribution of the liquid crystal panel unit due to the heat from the light source. However, in addition to the light source, an electronic component that generates heat is mounted on the liquid crystal display device. The heat distribution of the liquid crystal panel part may be biased by heat from such electronic components. Therefore, the ghost correction amount may be changed for each region in consideration of the uneven distribution of heat due to heat from the electronic component or the like.

The liquid crystal display device described above can be applied not only to a liquid crystal television but also to various devices including a liquid crystal panel unit such as a smartphone or an electronic book terminal.

In the first to third embodiments, a ghost parameter reference table is used to determine a ghost correction amount. However, the ghost correction amount may be determined by parameters, for example, without using such a table. Further, the parameter may be changed at a constant rate with respect to the distance from the light source without using a table. Specifically, for example, the parameter is set to increase by 1.1 times every 1 cm when the distance from the end of the liquid crystal panel is 0 to 5 cm, and becomes stronger toward the center of the liquid crystal panel. May be.

In the first to third embodiments, the LED is used as the light source of the backlight unit, but a light source other than the LED may be used.

In the first embodiment, a single light guide plate is used as the light guide, but for example, the light guide may have a combination of a plurality of strip-shaped light guide plates. Further, the light guide body may be, for example, a rod-shaped light guide bar in addition to the plate shape.

In the first embodiment, the LED modules (LEDs) are arranged on the left and right sides of the backlight unit (light guide), but the LED modules (LEDs) are arranged on at least one side of the backlight unit (light guide). It only has to be done. For example, as shown in FIG. 18, the LED modules 20 (LEDs 22) may be disposed on both upper and lower sides of the backlight unit (light guide 30). Also in this case, the area in the vicinity of the LED 22 may be the area Ar1, and the area away from the LED 22 by a predetermined distance may be the area Ar2. Note that the LED modules may be arranged on both the left and right sides or the upper and lower sides. For example, the LED modules may be disposed on the upper and right sides of the light guide. Further, the LED module may be disposed only on one of the upper side and the lower side of the light guide. The LED module may be disposed only on either the right side or the left side of the light guide.

In the first embodiment, the liquid crystal panel unit includes two regions, that is, a region Ar1 having a high temperature and a region Ar2 having a relatively low temperature. However, the liquid crystal panel unit may include three or more regions having different temperatures. The ghost correction amount may be changed for each of these areas. Ghost correction is performed more accurately. However, in reality, about three regions are sufficient. When the number of regions is more than that, it is considered that the effect is not obtained so much.

In the first and third embodiments, the area in the vicinity of the LED (area Ar1) and the area away from the LED by a predetermined distance (area Ar2) may be changed according to the temperature change. That is, since the temperature distribution of the liquid crystal panel changes depending on the ambient temperature or the like, the size of the region Ar1 and the region Ar2 (position of the boundary g) may be changed according to the temperature change.

In the edge light type backlight unit, the LED as the light source may be a top view type LED or a side view type LED. The top-view LED emits light in a direction perpendicular to the mounting surface of the mounting substrate, and the side-view LED emits light in a direction horizontal to the mounting surface of the mounting substrate.

In the first embodiment, the distance L (see FIG. 3) indicates the position of the boundary g and is set to about 3 cm, for example. However, the boundary g may be appropriately set according to, for example, the heat distribution.

In the second embodiment, the LEDs are arranged at equal intervals. However, LEDs (a plurality of light sources) may be arranged unevenly. FIG. 19 shows a modification of the second embodiment. As shown in FIG. 19, the LEDs 22 are arranged more densely in the end region of the backlight unit 150 than in other regions. In the end region, the LEDs 22 are arranged at an interval a1 in the X direction and at an interval b1 in the Y direction. In the central region, the LEDs 22 are arranged at an interval a2 in the X direction and at an interval b2 in the Y direction. The interval a1 is smaller than the interval a2, and the interval b1 is smaller than the interval b2. In this case, the number of LEDs 22 arranged in the end region of the backlight unit 150 is larger than the number of LEDs 22 arranged in other regions. The end region is likely to be dark, but in FIG. 19, the end region is bright. Further, the temperature is high in a region where the density of the LED 22 is high, and the temperature is low in a region where the density of the LED 22 is low. The driving of the liquid crystal panel unit is adjusted in accordance with such characteristics. In FIG. 19, the interval a1 may be smaller than the interval a2, and the interval b1 may be the same as the interval b2. The interval a1 may be the same as the interval a2, and the interval b1 may be smaller than the interval b2.

In the second embodiment, a plurality of LEDs can be driven independently in a direct backlight unit. However, a plurality of LEDs may be driven simultaneously. That is, the plurality of LEDs may not be driven independently. In this case, it is considered that the influence of heat from the LED on the heat distribution of the liquid crystal panel portion is reduced. However, the heat distribution of the liquid crystal panel unit may be affected by the heat from the electronic components and the like mounted on the liquid crystal panel unit. Even in such a case, the ghost correction is effective, and the ghost is appropriately corrected according to the heat distribution of the liquid crystal panel unit.

In each embodiment, the type of LED is not particularly limited. For example, an LED chip (light emitting chip) and an LED including a phosphor may be used. When the LED chip emits blue light and the phosphor receives light from the LED chip and emits yellow light, the LED emits light from the LED chip and light from the phosphor. Generate white light. Note that the number of LED chips included in the LED is not particularly limited.

The LED may include a phosphor that receives blue light from the LED chip and fluoresces green light and red light. In this case, the LED generates white light from the blue light from the LED chip and the light from the phosphor (green light, red light).

The LED may include a red LED chip that emits red light, a blue LED chip that emits blue light, and a phosphor that emits green light by receiving light from the blue LED chip. Such an LED can generate white light with red light from a red LED chip, blue light from a blue LED chip, and green light from a phosphor.

The LED may not contain any phosphor. For example, the LED includes a red LED chip that emits red light, a green LED chip that emits green light, and a blue LED chip that emits blue light, and mixes light from all LED chips to emit white light. It may be generated.

Note that embodiments obtained by appropriately combining the techniques disclosed above are also included in the technical scope of the present invention.

10 Liquid Crystal Panel 20 LED Module 21 Mounting Board 22 LED (Light Source)
30 Light guide (light guide member)
41 Reflective sheet 42 Backlight chassis 43 Diffuser plate 44 Prism sheet 45 Lens sheet 50, 150 Backlight unit (illumination unit)
51 LED Drive Unit 51a LED Driver 51b Counter 60 Temperature Sensor (Temperature Measuring Means)
DESCRIPTION OF SYMBOLS 70 Housing 80 Display control part 80a Color recovery part 80b Contrast adjustment part 80c Gamma correction part 80d Signal generation part 81 Liquid crystal controller part 82 Drive voltage value determination part 83 Correction part 84 Ghost voltage value determination part 85 Ghost parameter reference table 86 Memory 90 Liquid crystal driver 91 Source driver 92 Gate driver 110 Liquid crystal panel unit 120 Image data acquisition unit 200, 200a, 200b Liquid crystal display device Ar1 area (first area)
Ar2 region (second region)

Claims (9)

The liquid crystal display device includes a liquid crystal panel unit, an illumination unit that includes a plurality of light sources and supplies light to the liquid crystal panel unit, and a correction unit that performs ghost correction of the liquid crystal panel unit, The ghost correction amount is changed for each predetermined region of the liquid crystal panel unit according to the heat distribution of the liquid crystal panel unit. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal panel unit includes a first region and a second region having a temperature lower than that of the first region, and a ghost correction amount in the first region is equal to the first region. It is smaller than the ghost correction amount in the second region. 3. The liquid crystal display device according to claim 1, wherein the correction unit defines a voltage corresponding to a ghost correction amount by comparing the luminance of a predetermined line and the luminance of the next line in the liquid crystal panel unit. It has a plurality of parameter tables. 4. The liquid crystal display device according to claim 3, wherein the parameter table is provided for each temperature region of the liquid crystal panel unit. 5. The liquid crystal display device according to claim 4, wherein the parameter table is provided for each temperature. 6. The liquid crystal display device according to claim 1, further comprising temperature measuring means for measuring a temperature of the liquid crystal panel unit. 7. The liquid crystal display device according to claim 1, wherein the illumination unit includes a light guide member that guides light from the light source, and the plurality of light sources are provided at an end of the light guide member. It is arranged in the part. 7. The liquid crystal display device according to claim 1, wherein the illumination unit is disposed so as to overlap with the liquid crystal panel unit, and the plurality of light sources are disposed directly below the liquid crystal panel unit. And are driven independently of each other. 9. The liquid crystal display device according to claim 8, wherein the plurality of light sources are non-uniformly arranged.

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