JPH0817495B2 - Color television receiver - Google Patents

Description

The present invention relates to a color television receiver that displays a color image on a liquid crystal display using primary color signals obtained from video signals.

Conventionally, CR was used as the display for color television receivers.
T has been used a lot. Therefore, on the image sending side, the image sending method and characteristics are determined in consideration of the CRT light emission characteristics or driving form.

In recent years, various displays have been developed to improve the drawbacks of CRTs, but their electrical and visual characteristics are
Since it is different from, it cannot be directly replaced with CRT.

An object of the present invention is to solve this problem by using an image display body in which a color filter is mounted on a liquid crystal display body, and displaying the change in color of a video signal of a standard color television received by the image display body. An object of the present invention is to provide a color television receiver capable of displaying accurately on a display body.

In order to achieve such an object, the present invention provides a video signal demodulation for receiving a color television broadcast wave and demodulating a video signal in a color television receiver using a liquid crystal display body having a color filter as an image display body. Means, color signal demodulation means for demodulating the three primary color signals from the demodulated video signal, and driving means for driving the liquid crystal display body based on the demodulated three primary color signals. A signal correction that makes the liquid crystal display body reversely nonlinear so that the liquid crystal display body linearly displays the video signal in color by compensating for the nonlinearity in which the light transmittance shows a saturation tendency. Is added to the three primary color signals.

 The present invention will be described below with reference to the drawings.

FIG. 1 shows a color television receiver of the present invention.

The broadcast wave received by the antenna (1) becomes a video signal in the video signal demodulator (2), and the video signal is a luminance signal processing circuit (3), a color difference signal demodulation circuit (4), and a synchronization signal generating circuit. It is supplied to (9).

The signals from the luminance signal processing circuit (3) and the color difference signal demodulating circuit (4) are added to the primary color signal synthesizing circuit (5), and red,
Obtain the three primary color signals of green and blue.

The three primary color signals are supplied to the liquid crystal drive circuit (7) via the primary color signal processing circuit (6) and processed into signals that can be displayed on the liquid crystal display body (8).

The synchronization signal generation circuit (9) is a primary color signal processing circuit (6).
And a necessary timing signal to the liquid crystal drive circuit (7).

 FIG. 2 is a configuration example of the primary color signal processing circuit (6).

The three primary color signals (RG) obtained by the primary color synthesis circuit (5)
B) is inverted every vertical period by the inverters (11), (12) and (13) and the analog switches (14), (15) and (16), and the signal as shown in FIG. Is converted to.

The analog switches (14), (15) and (16) are supplied with an inversion signal from the synchronization signal generating circuit (9) every vertical period through an inversion signal input (17).

The alternating signals of the three primary colors for each vertical period are converted by the analog switches (18) to (26) for each horizontal period.
It is supplied to the output terminals V ₁ , V ₂ and V ₃ .

That is, in the first horizontal period, the R, G, B signals become V ₁ , V ₂ , and V ₃ signals, respectively, and in the second horizontal period, V ₂ , V ₃ , and V ₁
It becomes a signal, and becomes a V ₃ , V ₁ , V ₂ signal in the _third horizontal period.

The analog switches (18) to (26) receive switching signal inputs (27) to (27) from the synchronization signal generating circuit (9) at each horizontal period.
The switching signal is supplied via (29).

FIG. 3 shows a liquid crystal drive circuit (7) and a liquid crystal display body (8).
It is an example of the structure of the color filter of.

3 primary color signals, is switched for each horizontal period V ₁ ~V ₃
It becomes a signal and is supplied to each pixel corresponding to the three primary colors by the shift registers (30) to (32).

In this figure, R, G, B signals as V ₁ , V ₂ , V ₃ signals in the first horizontal period, B, R, G signals in the second horizontal period, G, B, in the third horizontal period. The R signal will be supplied.

In this way, the three primary color signals demodulated from the broadcast wave are processed into a signal form capable of driving the liquid crystal display.

Now, on the image transmitting side, since the display body is premised on CPT, the transmitted signal is preprocessed in order to correct the γ characteristic of the CRT.

The γ value of CRT is 2.5 to 3, and the voltage is plotted on the horizontal axis and the luminance is plotted on the vertical axis, resulting in a fingerprint curve as shown in FIG.

On the other hand, when the liquid crystal display body takes the light transmittance on the vertical axis,
As shown in FIG. 6, the light transmittance of the liquid crystal display shows a saturation tendency in the high voltage and low voltage application regions, and it can be seen that the dynamic range is narrower than that of the CRT. Particularly, there is a problem that the saturation in the white (corresponding to a portion having high luminance) direction is fast.

Therefore, in order to correct the three primary color signals in accordance with the light transmittance of the liquid crystal display, it is necessary to give the primary color signal synthesis circuit (5) nonlinearity. As a concrete means, a non-linear element such as a diode may be used together with the load resistance of the signal path. In other words, in order to compensate for the non-linear characteristics that easily cause color saturation as an image display body including a color filter, the signal level in the vicinity of the color saturation tendency of the three primary color signals is changed, and the signal level is a non-linear characteristic opposite to the light transmittance. The change in the display color of the image display body having the liquid crystal display body driven by the three primary color signals is made linear to make it difficult to saturate.

Next, there is a problem regarding color reproducibility. In the currently commercially available receiver, the demodulation axis of the color difference signal is appropriately set according to the color development characteristics of the CRT. This also applies to the liquid crystal display, and it is necessary to set the demodulation axis of the color difference signal to an appropriate value by using the dye of the color filter.

This can be done by adjusting the phase of the demodulated carrier wave added to the color difference signal demodulation circuit (4).

On the contrary, a means for controlling the hue by mixing the dyes of the color filter is also effective.

At present, the primary color signals being sent out are used to determine the color filter color scheme that provides the most visually pleasing tones.

As described above, the color television receiver of the present invention is
In the process of demodulating the three primary colors from the video signal, the three primary color signals are corrected according to the light transmittance characteristics of the liquid crystal display so as to compensate for the color saturation due to the rapid saturation of the light transmittance peculiar to the liquid crystal display. In addition, since the change of the voltage level applied to the liquid crystal display is converted into the opposite non-linearity to make the change of the display light of the liquid crystal display linear, the image having the liquid crystal display equipped with the color filter is displayed. The change in the display color on the display body can accurately display the change in the color of the received color television image signal, and has a wider dynamic range than that of the conventional color television receiver using the liquid crystal display body. can do. That is, according to the present invention, it is possible to provide a color television receiver having a small and lightweight liquid crystal display that can display a high-quality image with little deterioration in image quality even under the current color television standard system. .

[Brief description of drawings]

FIG. 1 is a color television receiver of the present invention, FIG. 2 is a structural example of a primary color signal processing circuit, FIG. 3 is a structural example of a liquid crystal driving circuit and a color filter of a liquid crystal display, and FIG. 4 is one vertical period. FIG. 5 shows the γ characteristic of the CRT and FIG. 6 shows the γ characteristic of the liquid crystal display. (1) ...... Antenna, (2) ...... Video signal demodulator (3) ...... Luminance signal processing circuit, (4) ...... Color difference signal demodulation circuit (5) ...... Primary color signal synthesis circuit, (6) ...... Primary color signal processing circuit (7) …… Liquid crystal drive circuit, (8) …… Liquid crystal display (9) …… Synchronous signal generation circuit (11), (12), (13) …… Inverter (14) to ( 16) ・ (18) to (26) …… Analog switch (17) …… Inverted signal input (27) to (29) …… Switching signal input (30) to (32) …… Shift register and sample holder

Claims (3)

[Claims] 1. A video signal demodulation means for receiving a color television broadcast wave and demodulating a video signal in a color television receiver using a liquid crystal display body having a color filter as an image display body, and demodulated. 3 from the video signal
The color signal demodulating means for demodulating the primary color signals and the driving means for driving the liquid crystal display body based on the demodulated three primary color signals are provided, and the color signal demodulating means has a light transmittance characteristic of the liquid crystal display body. In order to compensate the non-linearity in which the light transmittance shows a saturation tendency and linearly display the video signal in color on the image display body, signal correction for making the inverse non-linearity is added to the three primary color signals. Characteristic color television receiver. 2. The color signal demodulating means converts the color difference signal demodulated from the video signal into the three primary color signals, and the color difference signal is generated in accordance with the dye of the color filter mounted on the liquid crystal display. The color television receiver according to claim 1, wherein the value of the demodulation axis of the signal is set. 3. The color signal demodulating means adds signal correction for compensating for color saturation to the three primary color signals according to the light transmittance in a low voltage application region in the light transmittance characteristic of the liquid crystal display. The color television receiver according to claim 1, wherein