JPH061307B2 - Color display device - Google Patents

Description

The present invention relates to a color display device using liquid crystal.

The development of color televisions using liquid crystals is in progress, but one of the challenges in the process of this development is the realization of color display with good reproducibility and excellent color rendering. An object of the present invention is to provide a liquid crystal display device capable of such color display.

Hereinafter, the present invention will be specifically described with reference to the drawings illustrating the embodiments.

FIG. 1 is a cross-sectional structural view of a display portion of a liquid crystal display device according to the present invention, in which a polarizing layer 20 is provided on a transparent substrate 1 made of glass or the like.
Is formed, and the colored film 2 having a thickness of about 10 μm is further formed thereon. This colored film 2 is formed by coloring one surface of a polymer film such as polyvinyl alcohol (PVA) with ink, and a red film strip 21, a green film strip 22 and a blue film strip 23 having a fine width dimension are shown in FIG. As shown in, they are arranged regularly on one side. The production of the colored film having such a pattern is carried out by dividing the number of colors by using a photosensitive resin as in JP-A-55-18685. The transmitted light has wavelength dependence due to the colored film.

On the upper layer of the colored film 2, a transparent thin film 3 of about several hundred liters is adhered and formed for protection by an acrylic resin or the like.
Transparent electrodes X ₁ , X ₂ , X ₃ ... X are formed on the transparent thin film 3 and the upper layer.
_n is formed to match the pattern of the colored film 2, that is, one electrode corresponds to one strip. As shown in FIG. ₃ , the transparent electrodes X ₁ , X ₂ , X ₃ ... X _n are strip-shaped transparent electrodes Y ₁ , Y ₂ , arranged in a direction orthogonal to the transparent electrodes X ₁ , X ₂ , X ₃ ,.
Y ₃ ... _M is for pairing with the liquid crystal layer 5 made of nematic liquid crystal interposed therebetween to apply a voltage. The alignment layers 4 and 6 sandwiching the liquid crystal layer 5 are surface-treated on the liquid crystal layer side so that liquid crystal molecules are aligned in directions orthogonal to each other, and a known twisted effect is obtained. A transparent substrate 7 made of glass or the like is provided on the transparent electrodes Y ₁ , Y ₂ , Y ₃ ... _M. The transparent substrates 1 to 7 are integrally formed, but a neutral polarizing plate 8 which is separate from the transparent substrates 1 to 7 is arranged on the transparent substrate 7 side to form a crossed Nicols with the polarizing layer 20. Needless to say, the polarizing plate 8 may be attached to the transparent substrate 7.

Then, for example, a signal for displaying red is applied to the transparent electrodes X ₁ -Y ₁ , and signals for displaying green and blue are applied between the transparent electrodes X ₂ -Y _{1 and} between X ₃ -Y ₁ , respectively. The red, green, and blue colors having the luminances corresponding to the applied signals are displayed in the respective facing areas, and the apparent color mixture display is performed by these colors.

Now, in the display device having such a configuration, the polarization degree V of the optical system formed by combining the polarizing layer 20 and the neutral polarizing plate 8 is expressed as follows.

However, T _p : transmittance when both polarization axes are combined in parallel T _c : transmittance when both polarization axes are combined vertically T _p and T _c of the polarizing layer 20 and the polarizing plate 8 themselves are the entire surface However, since light passes through the colored colored films 2 colored red, green, and blue, when viewed as the entire optical system of the two polarizing layers (plates) and the colored films 2, the film strips of each color are The actual transmittances T _p and T _c differ depending on the light passing through 21, 22 and 23. For this reason, when the voltage applied to the electrodes for displaying each color is uniform, a color having a high degree of polarization appears preferentially, resulting in a color display having a poor color rendering property. The present invention is equipped with an electronic circuit for color adjustment as shown in FIG. 4 in order to correct this.

Next, this circuit will be described.

Matrix circuit of the circuit of the known chrominance signal color difference signals obtained from the (not _{shown) E R -E Y, E G} -E Y and _E B -E _{Y
(E R, E G, E} B are each red, green, primary color signal of blue .E _Y
Is a luminance signal) applied to the bases of the transistors 31R, 31G, 31B for adjusting the input impedance. A luminance signal E obtained from a known image amplification circuit (not shown) is given to the base of the similar transistor 31Y. The emitter outputs of the transistors 31R, 31G, 31B are given to the bases of the transistors 33R, 33G, 33B for color adjustment via the diodes 32R, 32G, 32B for level adjustment. The emitter of the transistor 31Y is connected to the emitters of the transistors 33R, 33G, and 33B via the level adjusting diode 32Y, the variable resistors 34R, 34G, and 34B, and the resistors. Diode 32R, 32G, 32B and transistor 33
The connection points of the R, 33G, and 33B bases are connected to a pull-down power source 35 via a resistor, and the power source 35 is also connected to the cathode of the diode 32Y via a resistor.

From the collectors of the transistors 33R, 33G, 33B, output signals E _R ′, E _G ′, corresponding to the sum of the input and the emitter input,
Although E _B ′ is obtained, this E _R ′, E _G ′,
E _B 'is determined by the resistance of the variable resistors 34R, 34G, 34B, and its collector output is a diode 36 for level adjustment.
Amplitude control transistors 37R, 37 via R, 36G, 36B
Given to the base of G, 37B. Variable resistors 38R, 38
The circuits connected to the emitters of the transistors 33R, 33G, 33B, including G and 38B, are for white level adjustment. The collectors of the transistors 37R, 37G, 37B are variable resistors 39R,
It is connected to the bases of 39G, 39B and transistors 40R, 40G, 40B. The amplitude of the collector output of the transistors 37R, 37G, and 37B changes according to the resistance value of the variable resistors 39R, 39G, and 39B. The collector outputs are given to the bases of the transistors 40R, 40G, 40B, and the emitter outputs of the transistors 40R, 40G, 40B are given to the collectors of the transistors 41R, 41G, 41B, and the resistance 4
3R, variable resistor 44R and resistor 45R, resistor 43G, variable resistor 4
4G and resistor 45G and resistor 43B, variable resistor 44B and resistor 4
It is given to the voltage dividing circuit consisting of 5B, and variable resistors 44R, 44G,
One end of each 44B is connected to the base of each of the transistors 41R, 41G, and 41B, or the other end thereof is connected to each emitter.

Then, the potentials of the emitters of the transistors 41R, 41G, 41B are output to the three-color switching circuit 46, and the three-color switching circuit 46 alternately supplies the three-color signals from the transistors 42R, 42G, 42B to the A / D converter 47. Output, and after sequentially converting the input signal into a digital signal of 8 gradations, sequentially applying electricity to the electrodes X ₁ and Y ₁ arranged so as to form a matrix pattern as in the above equation, That is, the output is made to the shift register 48 for scanning display.

If the transmittance ratio of the three colors of red, green, and blue based on the difference in the degree of polarization is now red: green: blue = 0.97: 1: 0.94, the variable resistors 34R, 34G, and 34B are used. Adjust the ratio of the signals E _R ′, E _G ′, and E _B ′ for the red, green, and blue display respectively. By setting it to 1, it is possible to correct the difference due to the light transmittance of the film strip of each color, and it is possible to realize a desired color display device with excellent color rendering properties. The signals E _R ′, E _G ′ and E _B ′ thus obtained are supplied to the transistor 37.
The variable resistors 39R, 39G, 39B and 44R, 44G, 44B are preset so that the amplitude and level are input to the R, 37G, 37B but suitable for the level judgment performed later by the A / D converter 47. It The signal E _R ′ or the like input to the transistor 37B or the like outputs a signal having an amplitude determined by the resistance value of the variable resistor 39R or the like, the emitter potential of the transistor 40R or the like changes according to this input signal, and the signal of the transistor 41R or the like changes. The current (which depends on the resistance value of the variable resistor 44R or the like) follows this, and as a result, a required color signal is obtained at the connection point between the resistor 45R or the like and the emitter of the transistor 41R or the like.

As described above, in the color display device according to the present invention, the liquid crystal layer and the coloring layers of a plurality of colors are interposed between the two polarizing layers, and the coloring layer portion corresponding to the region to which the voltage of the liquid crystal layer is applied. The liquid crystal display device is characterized by including a circuit for correcting the signal related to the display of each color according to the optical characteristics of each color portion of the colored layer It is possible to realize a color display device and a color television having excellent color rendition with excellent reproducibility of the original image.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a sectional structural view of a display portion of a liquid crystal display device according to the present invention, FIG. 2 is a pattern diagram of a colored film, and FIG. 3 is a transparent electrode. The pattern diagram and FIG. 4 are electronic circuit diagrams for color adjustment. 2 ... Colored film 5 ... Liquid crystal layer 8 ... Polarizing plate 20 ... Polarizing layer 33
R, 37R, 40R, 41R, 33G, 37G, 40G, 41G, 33B, 37B, 40
B, 41B ... Transistors 34R, 39R, 44R, 34G, 39G, 44G, 34B, 39B, 44B ... Variable resistors

Claims (1)

[Claims] 1. A liquid crystal layer and colored films of a plurality of colors are interposed between two polarizing layers so that each color of a colored film portion corresponding to a region to which an applied voltage of the liquid crystal layer is applied is revealed. In the color display device, the applied voltage of the liquid crystal layer for displaying each color is corrected according to the wavelength dependence of the transmittance of each color portion of the colored film and the wavelength dependence of the polarization degree of the two polarizing layers. A color display device is provided with a circuit for equalizing the transmittance of each color transmitted through the two polarizing layers and the colored films of the plurality of colors.