JPH11183894A - Uneven color correction device for color liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of unevenness in color. SOLUTION: The correction device is arranged in each chrominance signal in a color liquid crystal display device using grating elements. In this case, the correction device is provided with a correction coefficient output means 12 for previously storing correction coefficients for correcting the unevenness of luminance in each horizontal address of an input video signal and outputting a correction coefficient corresponding to each horizontal address of the input video signal and a means 2 for multiplying the input video signal by the correction coefficient outputted from the means 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for correcting color unevenness in a color liquid crystal display device using a grating element.

[0002]

2. Description of the Related Art In a color liquid crystal display device, R
In order to obtain three primary colors (red), G (green), and B (blue), a color filter formed by printing a coloring material of each color by printing or the like has been used. However, in a color liquid crystal display device using such a color filter, when white light from a light source is incident on each color pixel, light is not used because a complementary color component for that color pixel is wasted. There was a disadvantage that efficiency was poor.

Therefore, incident light is diffracted and separated using a grating (diffraction grating) element and dispersed into R, G, and B color components at a predetermined spatial period, and these color components are converged by a microlens array. Then, a color liquid crystal display device for making the light incident on a liquid crystal panel has already been developed.

FIG. 9 shows a schematic configuration of a color liquid crystal display device using a grating element.

The light source device 110 includes a grating element 1
It is arranged above the side of 20. The light source device 110
It comprises an elliptical reflecting mirror 111 and a lamp (for example, a metal halide lamp) 112 arranged at the focal position.

The parallel light emitted from the light source device 110 is:
The light is incident on the grating element 120 at a predetermined incident angle. When light enters the grating element 120, R
The color component, the G color component, and the B color component are diffracted at a predetermined dispersion angle.

[0007] The R, G, and B color components dispersed by the grating element 120 are positioned at different positions on the liquid crystal panel 130 by a microlens array (not shown) disposed below the liquid crystal panel 130. Is converged. In other words, the R color component is
The G color component is converged on the G pixel portion, and the B color component is converged on the B pixel portion.

Note that 120L is the grating element 12
0, 120R is the right side of the grating element 120, 130L is the left side of the liquid crystal panel 130, and 1 is the left side.
30R indicates the right side surface of the liquid crystal panel 130, respectively.

FIG. 10 shows a luminance distribution on the surface of the grating element 120 by the light source device 110. As can be seen from FIG.
The luminance at the left and right central parts on the surface of the zero element is larger than the luminance at the left part and the right part on the surface of the grating element 120.

[0010] As shown in FIG.
Of the R color components dispersed by 20, only the R color component reflected from the right half of the surface of the grating element 120 enters the liquid crystal panel 130. For this reason, the R-color component having a large luminance reflected from the central portion of the grating element 120 is incident on the left side of the lower surface of the liquid crystal panel 130. As shown in FIG. 11, the luminance on the left side of the screen is higher than the luminance on the right side.

[0011] As shown in FIG. 9, among the G color components dispersed by the grating element 120, only the G color component reflected from the center of the surface of the grating element 120 is incident on the liquid crystal panel 130. For this reason,
Since the G color component having a large luminance reflected from the central portion of the grating element 120 enters the central portion on the lower surface of the liquid crystal panel 130, the distribution of the G color component incident on the liquid crystal panel 130 and projected on the screen is shown in FIG. As shown in FIG. 12, the luminance at the center of the screen is higher than the luminance at both sides.

As shown in FIG. 9, among the B color components dispersed by the grating element 120, only the B color component reflected from the left half of the surface of the grating element 120 is incident on the liquid crystal panel 130. For this reason,
Since the B-color component having a large luminance reflected from the center of the grating element 120 is incident on the right side of the lower surface of the liquid crystal panel 130, the distribution of the B-color component incident on the liquid crystal panel 130 and projected on the screen is shown in FIG. As shown in FIG. 13, the brightness of the right side of the screen is higher than the brightness of the left side.

As described above, the horizontal direction (horizontal direction) of the screen
However, there is a problem that uneven brightness occurs in the R color component, the G color component, and the B color component.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus for correcting color unevenness in a color liquid crystal display device which can prevent the occurrence of color unevenness.

[0015]

According to the first aspect of the present invention, there is provided a color non-uniformity correcting device provided in a color liquid crystal display device using a grating element, provided for each color signal. Correction coefficient output means for preliminarily storing a correction coefficient for correcting luminance unevenness for each horizontal address of the input video signal and outputting a correction coefficient corresponding to the horizontal address of the input video signal, and outputting a correction coefficient to the input video signal And a means for multiplying the correction coefficient output from the means.

The color non-uniformity correction device in the second color liquid crystal display device according to the present invention is a color non-uniformity correction device provided for each color signal in a color liquid crystal display device using a grating element. Sampling means for sampling at a sampling cycle of
Horizontal address generation means for generating a horizontal address signal of an input video signal at a period twice as long as the sampling period, a correction coefficient for correcting luminance unevenness for each horizontal address defined by the horizontal address signal is stored; Correction coefficient output means for outputting a correction coefficient corresponding to the horizontal address generated by the horizontal address signal generation means, delay means for delaying and outputting the correction coefficient output from the correction coefficient output means by one sampling period, and correction coefficient Switching means for alternately switching and outputting the correction coefficient output from the output means and the correction coefficient output from the delay means every one vertical period is provided.

[0017]

Embodiments of the present invention will be described below.

[1] Description of First Embodiment A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a color unevenness correction circuit applied to a color liquid crystal display device using a grating element as shown in FIG. FIG. 1 shows a color unevenness correction circuit for the R color component.

An input video signal (R signal) is converted into a digital signal by the A / D converter 1. The output of the A / D converter 1 is sent to the multiplier 2 and multiplied by the correction coefficient output from the correction coefficient output circuit 10. The output of the multiplier 2 is converted into an analog signal by the D / A converter 3 and output as an output video signal.

The PLL 4 outputs a reference clock CLK. The reference clock CLK is sent to the A / D converter 1 and the D / A converter 3 as a sampling clock. The reference clock CLK is supplied to the correction coefficient output circuit 1
Also sent to 0.

The correction coefficient output circuit 10 includes a horizontal counter (H counter) 11 and a ROM 12. The horizontal counter 11 receives a horizontal synchronization signal as a horizontal reset signal (H reset). That is, the horizontal counter 11 is reset every time the horizontal synchronization signal is output. The horizontal counter 11 counts the input reference clock CLK and outputs the count value as a horizontal address signal (H address).

The ROM 12 stores, as a look-up table, correction coefficients for correcting the luminance unevenness of the R color component for each horizontal address. For example, assuming that the luminance distribution in the horizontal direction of the screen before the color unevenness correction for the R color component has a characteristic as shown in FIG. 2, the correction coefficient for the R color component is as shown in FIG. FIG. 4 shows the luminance distribution in the horizontal direction of the screen with respect to the R color component after being corrected by the correction coefficient.

The horizontal counter 11 receives a horizontal synchronizing signal as a horizontal reset signal (H reset). That is, the horizontal counter 11 is reset every time the horizontal synchronization signal is output. The horizontal counter 11 counts the input reference clock CLK and outputs the count value as a horizontal address signal (H address).

The horizontal address signal output from the horizontal counter 11 is sent to the ROM 12, and a correction coefficient corresponding to the input horizontal address signal is output from the ROM. Since the input image signal is multiplied by the correction coefficient by the multiplier 2, color unevenness in the horizontal direction for each color component of the input image signal is corrected.

The color non-uniformity correction device for the G and B components has the same configuration. However, in the color unevenness correction device for the G color component, RO in the correction coefficient output circuit
In M, a correction coefficient for correcting the luminance unevenness of the G color component for each horizontal address is stored as a lookup table. Similarly, in the color non-uniformity correction apparatus for the B color component, the ROM in the correction coefficient output circuit stores a correction coefficient for correcting the luminance non-uniformity of the B color component for each horizontal address as a look-up table.

[2] Description of Second Embodiment

A second embodiment of the present invention will be described with reference to FIGS.

FIG. 5 shows a color unevenness correction circuit applied to a color liquid crystal display device using a grating element as shown in FIG. FIG. 5 shows a color unevenness correction circuit for the R color component.

The input video signal (R signal) is converted into a digital signal by the A / D converter 1. The output of the A / D converter 1 is sent to the multiplier 2 and multiplied by the correction coefficient output from the correction coefficient output circuit 20. The output of the multiplier 2 is converted into an analog signal by the D / A converter 3 and output as an output video signal.

From the PLL 4, the first reference clock CLK
1 and the second reference clock CLK2 obtained by dividing the first reference clock CLK1 by two are output. That is, the frequency of the second reference clock CLK2 is １ ／ of the frequency of the first reference clock CLK1.

The first reference clock CLK1 is sent to the A / D converter 1 and the D / A converter 3 as a sampling clock. The second reference clock CLK2 is sent to the correction coefficient output circuit 20.

The correction coefficient output circuit 20 includes a horizontal counter (H counter) 21, a ROM 22, and a delay circuit (DLY).
23 and a changeover switch (SW) 24.

The horizontal counter 21 is reset every time a horizontal synchronizing signal (H reset) is output. The horizontal counter 21 counts the input second reference clock CLK2, and outputs the count value as a horizontal address signal (H address). Therefore, the frequency of the reference clock CLK of the first embodiment and the frequency of the first reference clock CL
Assuming that K1 is the same, while the horizontal address signal is output twice from the horizontal counter 11 of the first embodiment, the horizontal counter 21 of the second embodiment outputs a horizontal signal at a rate of once. An address signal is output.

The ROM 22 stores, as a look-up table, correction coefficients for correcting luminance unevenness of the R color component for each horizontal address output from the horizontal counter 21. Therefore, the number of correction coefficient data is halved as compared with the first embodiment.

The horizontal address signal output from the horizontal counter 21 is sent to the ROM 22, and a correction coefficient corresponding to the input horizontal address signal is output from the ROM 22. This correction coefficient is sent to the delay circuit 23 and to the changeover switch 24. The delay circuit 23 delays the input correction coefficient by one cycle of the first reference clock CLK1, and outputs the delayed correction coefficient. The correction coefficient delayed by one cycle of the first reference clock CLK1 output from the delay circuit 23 is sent to the changeover switch 24.

The changeover switch 24 is switched every vertical period by a vertical period signal. For example, OD
It is assumed that the changeover switch 24 selects the output from the ROM 22 during the D field, and the changeover switch 24 selects the output of the delay circuit 23 during the EVEN field.

For example, if the correction coefficients for the addresses 0, 1, 2, and 3 stored in the ROM 22 are values (2 bits in this example) as shown in FIG.
D) In the field, horizontal addresses 0, 1,.
As shown in FIG. 6, a correction coefficient is output from the changeover switch 24 for 2 and 3. On the other hand, in the even field (EVEN) field, for example, the correction coefficient as shown in FIG.

That is, in the odd field, the correction coefficient for the horizontal address n is output from the correction coefficient output circuit 20 when the horizontal address is n, and in the even field, when the horizontal address n is the horizontal address (n-n).
The correction coefficient for 1) is output from the correction coefficient output circuit 20.

Considering one field, the correction coefficient for the horizontal address is as shown by a solid line in FIG. 8, and the number of bits of the correction coefficient is doubled in a pseudo manner. Therefore, in the second embodiment, compared to the first embodiment,
Since the number of bits of the correction coefficient stored in the ROM can be reduced and the number of correction coefficients stored in the ROM can be reduced, there is an advantage that the capacity of the ROM can be reduced.

The color non-uniformity correction device for the G and B components has the same configuration. However, in the color unevenness correction device for the G color component, RO in the correction coefficient output circuit
In M, a correction coefficient for correcting the luminance unevenness of the G color component for each horizontal address is stored as a lookup table. Similarly, in the color non-uniformity correction apparatus for the B color component, the ROM in the correction coefficient output circuit stores a correction coefficient for correcting the luminance non-uniformity of the B color component for each horizontal address as a look-up table.

[0042]

According to the present invention, it is possible to obtain an apparatus for correcting color unevenness in a color liquid crystal display device which can prevent the occurrence of color unevenness.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a color shading correction circuit according to a first embodiment.

FIG. 2 is a graph showing an example of a luminance distribution in a horizontal direction of a screen before color unevenness correction for an R color component.

FIG. 3 is a graph showing a correction coefficient for an R color component.

FIG. 4 is a graph showing a luminance distribution in a horizontal direction of a screen with respect to an R color component after being corrected by a correction coefficient.

FIG. 5 is a circuit diagram showing a color shading correction circuit according to a second embodiment.

FIG. 6 is a graph showing an example of a correction coefficient output from a changeover switch 24 for horizontal addresses 0, 1, 2, and 3 in an odd (ODD) field.

FIG. 7 is a graph showing an example of a correction coefficient output from the changeover switch 24 for horizontal addresses 0, 1, 2, and 3 in an even (EVEN) field.

FIG. 8 shows a horizontal address 0 when considered in one field,
4 is a graph showing correction coefficients for 1, 2, and 3.

FIG. 9 is a schematic diagram showing a schematic configuration of a color liquid crystal display device using a grating element.

FIG. 10 is a graph showing a luminance distribution on a grating element surface by a light source device.

FIG. 11 is a graph showing a distribution of R-color components incident on a liquid crystal panel and projected on a screen.

FIG. 12 is a graph showing a distribution of a G color component incident on a liquid crystal panel and projected on a screen.

FIG. 13 is a graph showing a distribution of a B color component incident on a liquid crystal panel and projected on a screen.

[Explanation of symbols]

 Reference Signs List 1 A / D converter 2 Multiplier 3 D / A converter 4 PLL 10 Correction coefficient output circuit 11 Counter 12 ROM 20 Correction coefficient output circuit 21 Counter 22 ROM 23 Delay circuit 24 Switching switch

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H04N 9/30 H04N 9/30

Claims (2)

[Claims] 1. A color unevenness correction device provided for each color signal in a color liquid crystal display device using a grating element, wherein a correction coefficient for correcting luminance unevenness is stored in advance for each horizontal address of an input video signal. Correction coefficient output means for outputting a correction coefficient corresponding to the horizontal address of the input video signal, and means for multiplying the input video signal by the correction coefficient output from the correction coefficient output means. An uneven color correction device for a color liquid crystal display device. 2. A color liquid crystal display device using a grating element, comprising: a color unevenness correction device provided for each color signal, wherein sampling means for sampling an input video signal at a predetermined sampling period; Horizontal address generation means for generating a horizontal address signal of an input video signal in a cycle of: a correction coefficient for correcting luminance unevenness for each horizontal address defined by the horizontal address signal is stored in advance and the horizontal address signal generation means Correction coefficient output means for outputting a correction coefficient corresponding to the horizontal address generated by the correction coefficient output means, delay means for delaying the correction coefficient output from the correction coefficient output means by one sampling period and outputting the same, and output from the correction coefficient output means Between the correction coefficient output from the delay means and the correction coefficient Color unevenness correction device of the color liquid crystal display device, characterized by comprising means, switching outputs alternately switched between every.