JPS6395786A - Liquid crystal television - Google Patents

Abstract

PURPOSE:To obtain a high picture quality displaying image with a satisfactory gradation and without a hue dislocation by considering the characteristic of a television signal and a liquid crystal panel, correcting an inputted television signal and keeping the proportional relation of the luminance of an original picture and the luminance of a displaying picture. CONSTITUTION:Three primary color signals 9-11 are respectively inputted to reverse gamma correcting circuits 12-14, and three primary color signals 15-17 with the corrected size can be obtained. After the corrected three primary color signals 15-17 are time-division-mixed on accordance with the constitution of the color dot of a color filter on a color liquid crystal panel 19 in a liquid crystal panel driving circuit 18, the signals are inputted to a color liquid crystal panel 19. The relation of an impressed voltage V and the transmitted light quantity, namely, a luminance Y of a color liquid crystal panel 19 is as shown in the figure. The input output characteristic of the reverse gamma correcting circuits 12-14 is set by considering a color liquid crystal panel characteristic and a gamma correcting characteristic. Thus, a luminance I of the original picture and the luminance Y of the displaying picture are in a proportion relation, and the high picture quality displaying picture with a gradation and without a hue dislocation can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal television that displays television images on a liquid crystal panel.

[Conventional technology]

In recent years, so-called liquid crystal televisions, which display television images on a liquid crystal panel, have come into widespread use.

Conventionally, in these liquid crystal televisions, a voltage proportional to the magnitude of the reproduced luminance signal or red, green, and blue color signals is applied to the liquid crystal panel to display monochrome or color television IXhIiR.

[Problem that the invention seeks to solve]

In the cathode ray tube conventionally used for displaying television-11 images, the brightness MY is proportional to the applied voltage (2) to the approximately 2.2 power, as shown in FIG. Therefore, the magnitude V of the television signal input to the television reception (attenuation) is
As shown in FIG. 4, gamma correction is performed in advance in consideration of the characteristics of the cathode ray tube so that the brightness I of the original image is proportional to the approximately 172.2 power. Therefore, the luminance factor of the original image and the luminance of the displayed image YIr:i are proportional as shown in the 11th equation and FIG.

Y2, +V22=1(K2IV22)”=3I(
Kl, K2. (K3 is a constant) However, as shown in an example in FIG. 6, the relationship between the amount of transmitted light, that is, the brightness Y, and the applied voltage V of a liquid crystal panel is different from that of a cathode ray tube. Therefore, the regenerated luminance signal or red, green,
In conventional LCD televisions, in which a voltage proportional to the magnitude of the color signal on the back is applied to the LCD panel, the relationship between the luminance factor of the original image and the luminance Y of the displayed image is shown in Figure 7. , was not proportionate. In other words, conventional monochrome LCD TVs have the disadvantage that the gradation of light and shade decreases, and conventional color LCD TVs have the disadvantage that the gradation decreases and the ratio of red, green, and back of the displayed image decreases. There was a drawback that there was a shift in hue due to the difference from the original image. For example, in the original image, the ratios of red, green, and blue are 100% and 1, respectively.
The colors that are 00% and 50% are red,
When the ratios of green and blue are 100%, 100%, and 80%, respectively, the displayed image becomes more evening-like than the original image.

[Means for solving problems]

The liquid crystal television according to the present invention includes means for inputting a television signal, a liquid crystal panel, and means for displaying a television image based on the television signal on the liquid crystal panel, and the television li! 111M! The means for displaying corrects the magnitude of the television signal and applies it to the liquid crystal panel so that the brightness of the original image represented by the television signal is proportional to the difference in the display image displayed on the liquid crystal panel. I try to do that. by this,
A high-quality display image with good gradation and no hue shift can be obtained.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of a liquid crystal television according to the present invention. A television signal 2 input from an antenna 1 is tuned to a composite television signal 4 by a detection circuit 3.
is output as A Y/C separation circuit 5 separates a luminance signal 6 and a chroma signal 7, and a color signal reproduction circuit 8 reproduces three primary color signals, a red signal 9, a green signal 10, and a blue signal 11. These three primary color signals are signals that have been gamma corrected in accordance with the characteristics of the cathode ray tube. 3 primary color signals 9-1
1 are respectively input to inverse gamma correction circuits 12 to 14, and three primary color signals 15 to 17 whose magnitudes have been corrected are obtained. The corrected three primary color signals 15 to 17 are subjected to time-share mixing in the liquid crystal panel drive circuit 18 according to the configuration of color dots of the color filter on the color liquid crystal panel 19, and then
The color television image is input to the color liquid crystal panel 19 and displayed.

The relationship between the applied voltage (2) to the color liquid crystal panel 19 and the amount of transmitted light, that is, the luminance Y, is as shown in FIG.

The input/output characteristics of the reverse gamma correction circuits 12 to 140 are set as shown in FIG. 8, taking into account the characteristics of the color liquid crystal panel shown in FIG. 6 and the gamma correction characteristics shown in FIG. 4. Therefore, the brightness (2) of the original image and the brightness Y of the displayed image are in a proportional relationship, and a high quality display image with good gradation and no hue shift can be obtained.

FIG. 2 is a block diagram of a second embodiment of the liquid crystal television according to the present invention. This embodiment is an embodiment of a monochrome liquid crystal television, and the operation is the same as that of the first embodiment until the Y/C/M branch circuit 5 brightness signal 6 is obtained. The luminance signal 6 is input to an inverse gamma correction circuit 20, and the magnitude-corrected luminance signal 21 passes through a liquid crystal drive circuit 22 and is input to a monochrome liquid crystal panel 23 to display a monochrome television image. The characteristics of the monochrome liquid crystal panel and the characteristics of the inverse gamma correction circuit are shown in FIGS. 6 and 8, respectively, as in the first embodiment.
As shown in the figure, a display image with good gradation can be obtained.

〔Effect of the invention〕

As explained above, the liquid crystal television according to the present invention corrects the input television signal by taking into account the characteristics of the television signal and the liquid crystal panel, thereby improving the proportional relationship between the brightness of the original image and the brightness of the number of display pixels. By maintaining this, it is possible to obtain a high-quality display image with good gradation and no hue shift.

[Brief explanation of the drawing]

11.4 and 2 are block diagrams of the first and second practical examples of the present invention, respectively, FIG. 3 is a characteristic diagram of a cathode ray tube, FIG. 4 is a gamma correction characteristic diagram, and 5 +ff1 (+ is the original Figure 6 is a diagram showing the relationship between H7jIi image brightness and cathode ray tube brightness, Figure 6 is a characteristic diagram of the liquid crystal panel, Figure 7 is a diagram showing the relationship between original image brightness on a conventional LCD TV and LCD panel brightness, and Figure 8 is a diagram showing the implementation of the present invention. Input/output characteristics of inverse gamma correction circuit in example 1 and 4
It is. 1... Antenna %2... Television signal, 3... Synchronization/detection circuit, 4...
Composite television dibon signal, 5... Y/C separation circuit, 6... Luminance 1g, 7... Chroma signal, 8... Color signal regeneration circuit, 9-11...
・・Gamma corrected color signal, 12~14.20...
...Reverse gamma correction! E rotation, 15-17... Corrected color signal, 18.22... Liquid crystal panel drive circuit, 19° 23... Liquid crystal panel, 26
...... Gamma corrected degree signal, 21...
...Corrected brightness number. Agent Patent Attorney Uchihara 1.7=,'”day
.

Claims (1)

[Claims] In a liquid crystal television comprising means for inputting a television signal, a liquid crystal panel, and means for displaying a television image based on the television signal on the liquid crystal panel, the means for displaying the television image is configured to input a television signal according to the television signal. A liquid crystal television, characterized in that a signal whose magnitude of the television signal is corrected is applied to the liquid crystal panel so that the brightness of the original image represented by the original image is proportional to the brightness of the display image displayed on the liquid crystal panel.