JPH01277283A - Color liquid crystal display element - Google Patents

Abstract

PURPOSE:To enable almost perfect black to be displayed on multiplex-driven color liquid crystal display element by forming the layer thickness of a liquid crystal corresponding to the dot of each color at a value in which a transmission factor shows the minimum value for light transmitting the filter of each color at the time of impressing a bias voltage by multiplex driving between confronting electrodes. CONSTITUTION:The layer thickness of the layer of the liquid crystal 16 of each color interposed between first and second electrodes 13 and 14 corresponding to each color of color filters 17 is formed at the value in which the transmission factor shows the minimum value for the wavelength light of each color transmitting the dot part of each color in a state where the bias voltage of a signal for time divisional driving is impressed between the first and second electrodes 13 and 14. In other words, the layer thickness(gap) dR, dB, and dG of the liquid crystal at parts corresponding to the color filters of R, G, and B are set at thickness in which the transmission factor shows the minimum value for the light of respective wavelength transmitting the part in the state where the bias voltage is impressed. In such a way, an almost dark state can be obtained in the state where the bias voltage is impressed, that is, in an OFF state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to display devices and devices used in color televisions and the like, and particularly to a one-color liquid crystal display element equipped with color filters of three primary colors.

[Prior art]

Color liquid crystal display elements are used in mm display devices such as televisions. This color liquid crystal display element includes: one substrate on which a plurality of transparent scanning electrodes are formed; the other substrate on which a plurality of transparent signal electrodes facing the scanning electrodes are formed; and the relationship between these substrates. an intervening liquid crystal, a pair of polarizing plates disposed outside the substrate, and a plurality of the 71! A color filter is provided corresponding to the scanning electrode and colored in three primary colors of red, green, and blue.

Then, at the part where the scanning electrode and the signal electrode are separated, 1
Three dot portions are formed, one cumulative force is formed by three adjacent dot portions each having the three primary color filters, and a color image is formed by a plurality of the pixels.

Such color liquid crystal display elements have a large number of pixels and are driven in high time divisions, so they are required to have high-speed response and high contrast. ``In order to increase the response speed, it is desirable to increase the value of Δε of the liquid crystal and to decrease the value of the electric field, that is, the liquid crystal layer thickness d. In order to increase the contrast, if the wavelength of the incident light is 559 m, the product of the refractive index anisotropy Δn of the liquid crystal and the liquid crystal layer thickness d (μm), Δn-d, must have a value of 1.1. It is acknowledged that satisfaction is good.

Furthermore, the above-mentioned color liquid crystal display element is required to have good color balance. However, in a liquid crystal display element in which a pair of polarizing plates are arranged so that the polarization axes are parallel to each other, when the dots of each color are driven by a single power supply voltage, the light that passes through the dots of each of the three colors is The transmittance will be different. This is the refractive index anisotropy (
This is because Δn (hereinafter referred to as Δn) is different, and the transmittance is determined by Δn−d, the product of Δn and the liquid crystal layer thickness d. As a result, the light transmitted through the liquid crystal display element appears colored. In other words, since the transmittance of each wavelength of light that should be transmitted through each color filter is different, the entire screen of the liquid crystal display element appears to be biased toward a specific color. For example, in a simple matrix type liquid crystal display element, the transmittance of red light is high, resulting in an overall reddish, or sepia-colored display.

In order to solve the above-mentioned problem, the liquid crystal display element of the IJ socks has a simple structure in which the wavelength dependence of the transmittance is small and the value of Δn of the liquid crystal is 0.157, for example, so that the above-mentioned conditions are satisfied. In this case, the liquid crystal layer thickness was set to about 7 μm.

On the other hand, in IJ Lux's liquid crystal display element, the thickness of the liquid crystal layer is changed for each part corresponding to the color filter of each color. It is proposed that. Such a structure is, for example, disclosed in JP-A-60
-159823 publication, 60-159830 publication, 60-
159827 publication%60-159831 publication, 61-9
These are disclosed in JP 8330 and JP 61-121033, respectively. The liquid crystal layer thickness of each part shown in these outputs is different for each part corresponding to red (R), green (G), blue (B), and filters.

This layer thickness is Δ for each light transmitted through the R, G%B filter.
As shown in Fig. 15, which shows the transmittance for n-d, Δn at the point (α1, ``*s''l) where the transmittance shown by the light transmittance curves WjAB, G, and R of each color first shows the minimum value.
-d is set to match the value of Δn·d of the portion where each color filter is formed. In this manner, in an active matrix type liquid crystal display element, color balance is improved by varying the thickness of the liquid crystal layer in the portions corresponding to each color filter. This is because in an active matrix type liquid crystal display element, a static voltage is essentially applied to the liquid crystal. At the voltage va obtained and the voltage b obtained in the brightest state, it operates off, and in the off state, the value of Δnod, which is disturbed by the arrangement of liquid crystal molecules, is qualitatively 5s different from the value of Δn-d in the initial alignment state. This is because they are equal.

[Invention or problem to be solved]

However, in a simple matrix type liquid crystal display element, when the liquid crystal layer thickness is reduced in order to increase the response speed, the value of Δn-d also becomes smaller, which increases the wavelength dependence of the transmittance and causes significant coloring. . Conversely, increasing the value of Δn-d has the disadvantage that viewing angle characteristics deteriorate. Furthermore, in a simple matrix liquid crystal display element, each dot section is driven in a multiplex manner, so that a bias voltage is also applied between the opposing electric machines of the dot sections that are in the OFF state. That is, in FIG. 16, a voltage of 188 is applied in the off state, and a voltage of Vb is applied in the on state. Therefore, the orientation of the liquid crystal corresponding to the dot part in the off state changes depending on the bias voltage, and the value of Δn·d in the initial state as in the active matrix type described above or the value of Δn·d for each dot part corresponding to each color filter changes. By setting the values of α8, α7, and α3 shown in FIG. 15, it is not possible to match the color balance.

As described above, it was difficult to adjust the color balance of the conventional simple liquid crystal display device (IJ socks).

The present invention has been made in view of the above-mentioned circumstances, and its object is to provide a simple matrix color liquid crystal display element with good color balance and fast response speed.

(Means for solving the IN! chain) In order to achieve the above-mentioned object, the present invention provides a plurality of first and second 11L pole, and the first and second
a plurality of color filters formed corresponding to at least one of the electrodes and colored in at least three primary colors of red, green, and blue; and a liquid crystal interposed between the first and second electrodes. The above-mentioned No. 1. In a color liquid crystal display device in which a plurality of dot portions formed at the intersection of the first and second electrodes are sequentially time-divisionally driven by sequentially applying a voltage to the second electrode, the first and second electrodes ．．
The layer thickness is formed to have a minimum value of the transmittance for the wavelength light of each color that passes through the dot portion of each color while the bias voltage of the time-division drive signal is applied between the second electrodes. It is.

[Effect]

In the present invention, in a time-divisionally driven simple matrix type color liquid crystal display element, the quasi-crystals in the portions corresponding to the filters of each color have a thickness of 70 layers set as follows.

Using a liquid crystal with wavelength dependence of refractive index anisotropy Δn as shown in FIG.
WC4, FIG. 5, and FIG. 6 show the change in transmittance with respect to the liquid crystal layer thickness (gap) when 1 is applied. Here, Figure 4 shows that for red (λ = 61 Qnm) light,
On the other hand, in Figure 5, for green (J = 540 nm) light,
FIG. 6 shows the relationship between the gap (μm) and the transmittance for blue (λ=460 nm) No. 9. These figures 1 to 2 K Oite, V, (OFF), V
, (OFF), and Vs (OFF) are voltages for controlling the dot portion to a light blocking state (OFF), which corresponds to a bias voltage. As shown in Figure 4, red (λ=
610 nm), when there is no electric field and the gap dR is about 4.6 Jim, the transmittance T shows a minimum value, and as the pressure increases, the transmittance T shows a minimum value.The value of the gap dR increases. I feel nervous. Also, as shown in Figure 5, green (λ=540n
m), the gap d0 is approximately 3.9 without an electric field.
When sm, the transmittance T shows a minimum value, and as the voltage increases, the value of the gap do, which shows the minimum value of the transmittance T, increases. Furthermore, as shown in Figure 6, for blue (λ = 460 nm) light, the transmittance shows a minimum value when the gap d is approximately 3.1 am without an electric field, and as the voltage increases, the transmittance decreases. The value of the gap d, which indicates the minimum value of T, becomes large.

Since the color liquid crystal display device of the present invention is multiplex driven, a bias voltage is also applied to the light-blocking state (off state Th) (K controlled driver) B. Therefore, R
,B%GThe thickness of the liquid crystal layer in the part corresponding to each color filter, (
Gap) dR% d1 and dG are set to thicknesses that exhibit a minimum transmittance for each wave of light that passes through that portion when the bias voltage is applied. For example, in Figures 4 to 6, if the bias voltage is v3, dR is about 5.3 mm, and dG is about 4.7.
mm%dB is approximately 3.7jm. With this configuration, the color liquid crystal display element of the present invention is in an almost completely dark state when the bias voltage is applied, that is, in the off state. Furthermore, the liquid crystal layer thickness is small and the electric field applied to the liquid crystal is strong.

〔Example〕

Below, an example using the present invention will be described in Figures 1 to 2.
This will be explained in detail with reference to the figures.

The lower substrate 11 and the upper substrate 12 are a pair of well-structured glass substrates. The pair of lower and upper substrates 11 and 12 are arranged to face each other and are bonded together with a frame-shaped sealing material 15 at a predetermined distance.

Of these pair of substrates 11 and 12, proteins such as gelatin and casein are formed on the upper surface of the lower substrate 11 at a temperature of about 1 am, and after patterning, a color filter is dyed with a predetermined dye. 17 are formed in an array.

This color filter 17 consists of filters 17R, 117G, and 17B that transmit light of red, green, and blue wavelengths, and these filters 17R, 117G, and 17B are arranged repeatedly to form vertical stripes in FIG. is formed. And filters 17R, 17G, 1
7B, the liquid crystal layer thicknesses of the portions corresponding to these filters 17R, 17G, and 17B are different layer thicknesses d3 and d, respectively.
, dB, and are formed to have different film thicknesses. On top of this color filter 17, a transparent filter 18 having a two-layer structure is formed. This protective film 18 is closely attached to the color filter 17 and has a thickness of approximately 0.3 to 0.0 mm.
It consists of a resin layer 18a with a thickness of about 4 μm and an insulating layer 18b with a thickness of about 150 OA@, which is not attacked by acids and alkalis and does not penetrate therethrough. The resin layer 18a is made of acrylic epoxy resin (for example, Japan Synthetic Rubber JSS-1
6)'lk spin coded and fired. The insulating layer 18b is formed by sputtering silicon oxide (Sin). And this protective film 1
A plurality of signal electrodes 13 are arranged in a vertical direction on the color filter 1γ in correspondence with the filters 17R, 1'7G, and 17B of each color of the color filter 1γ.

This signal electrode 13 is a transparent electrode made of ITO.

Further, the signal electrode 13 is covered with an alignment film 19 made of polyimide resin.

On the other hand, on the surface of the upper substrate 12 facing the lower -j substrate 11, a large number of transparent scanning electrodes 14 made of ITO are arranged in a horizontal direction directly opposite to the signal electrodes 13, as shown in FIG. ing. The surface of this scanning electrode 14 is covered with a layer 111!20 made of polyimide resin. The surfaces of each of the above-mentioned alignment films 19 and 20 are subjected to two-ping processing in a predetermined direction. Each of the alignment films 19.
20 and a region surrounded by the sealing material 15, a liquid crystal 16 is sealed. Further, each electrode 13.14 has a lead portion 13a, 14a extending across the sealing material 15 to an end of each electrode substrate 11.12, and is connected to each electrode terminal 13b, 14b.

Further, on the outside of the lower substrate 11 and the upper substrate 12, a pair of polarizing plates 21 are provided with polarizing axes parallel to each other.
21 are arranged, thereby forming a TN type liquid crystal element.

The dR, d, %d of the liquid crystal is determined by the wavelength transmitted through each color filter when a bias voltage is applied to the liquid crystal of each dot part when each dot part is multiplex driven. The thickness is set so that the transmittance of light exhibits a substantially minimum value.

In a color liquid crystal display element having such a structure, a plurality of portions where one scanning electrode 14 intersects with three signal electrodes 13, . Dora of each color) fffi
One pixel is formed by three dots, one for each color, and this lI! ll1
A large number of g are arranged in a matrix. Then, this force 2-liquid crystal display element is multiplex driven,
Information such as television images is displayed in color by controlling the color tone and transmitted light intensity of the large number of pixels described above.

The spectral transmission characteristics in the on and off states when each gap dR%d, dB is set in this way are shown in FIGS. 7 to 10. 7 and 8 show dR, do,
The dB is 4.7 m, 4.2 m, and 3.8 μm, respectively, and the applied voltage in the off state is 2.9 μm.

In Figures 9 and 10, dRld and %d are each 5.
．． 3Bm, 4.7 sm, and 4.0 am, and the applied voltage in the off state at this time is 3.1V. As shown in Figs. 8 and 10, the spectral transmittance curve R of the dot part set to the liquid crystal layer thickness dR of the part corresponding to the red filter shows the minimum value when the wavelength λ is around 600 nm, and The liquid crystal layer thickness d of the corresponding part. The spectral transmittance curve G of the dot part set to 100 nm shows the minimum value at a wavelength of around 540 nm, and the spectral transmittance curve B of the dot part with the liquid crystal layer thickness dBKJ of the part corresponding to the blue filter determined as follows. As is clear from these spectral characteristic diagrams, the liquid crystal display element of this example can obtain an almost complete dark state when a bias voltage is applied, and has a good color balance. is also good.

In addition, the dR for red (λ = 610 nm) is 4.7 am.
Figure 11 shows the transmittance characteristics with respect to the applied voltage when set to 5.3 μm and 5.3 μm.
On the other hand, Figure 12 shows the transmittance characteristics with respect to the applied voltage when do is set at 4.2 am and 4.7 amK.
= 460 nm) with 'cdB of 3.8 mm and 4.
FIG. 13 shows transmittance characteristics with respect to applied voltage when set to 0 μm. Here, the drive signal is 1156du
ty signal is used, and the element temperature is 30°C. As shown in FIGS. 11 to 13, d R” 4.7 u
rn d G ”” 4.2 am d B ”
When selecting 3.8 srn and dR=5.3μm
m, do=4.2 am.

When dB = 4- Op m is selected, V = 2.9 V and V = 3. Although an almost complete dark state can be obtained with IV, the contrast ratio of the former is small, and the contrast ratio of the latter is too large. Therefore, the latter is more desirable as a liquid crystal display element.

Furthermore, dR was adjusted to 55-8a in the same manner as in the above-mentioned example.
, dg are set to 4.2 am, and dB is set to 4.8 am, the same effects as in the above embodiment can be obtained. In this case, the contrast ratio is extremely high at 22.4.

That's all I said! I! In the example, if the value of Δn-ct between the refractive index anisotropy Δn of the liquid crystal and the liquid crystal layer thickness d is less than 0.4, the viewing angle characteristics will be poor, and if the value of Δn·d is 0.4 or less, the viewing angle characteristics will be poor.
If it is 9 or more, the liquid crystal layer thickness d must be increased, and the electric field strength applied to the liquid crystal becomes weak (resulting in a slow response speed. Therefore, in this example, the value of Δn-d is 0. It is desirable that it be in the range of .45 to 0.8.

FIG. 14 shows a modified example of the embodiment described above, and the same components as in the embodiment shown in FIG. As shown in FIG. 14, the color filter 117 includes filters 117B and 11 of each color.
7o and 117m are formed adjacent to each other. In this modification, the same effect can be obtained by changing the film thickness of each of the filters 117B, 117G, and 117R of the color filter 117 and setting the liquid crystal layer thicknesses dR, do, and dB in the same manner as in the above-described embodiment. .

〔Effect of the invention〕

In the color liquid crystal display element of the present invention, the layer thickness of the liquid crystal corresponding to the dots of each color is such that the thickness of the liquid crystal layer corresponding to the dots of each color has a [minimum transmittance] with respect to the light transmitted through the filter of each color when a bias voltage by multiplex drive is applied between opposing electrodes. Since it is formed to a value that indicates the value, it is possible to display almost complete black in a multiplex-driven color liquid crystal display element.
The color balance will also be better. Furthermore, since the liquid crystal layer thickness is small, the electric field strength applied to the liquid crystal is large and the response speed is fast.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and FIG.
2 is a plan view showing an embodiment of the present invention; FIG. 3 is a graph showing the wavelength dependence of refractive index anisotropy regarding the liquid crystal used in the present invention; FIG. 4 is a graph showing the transmittance versus liquid crystal layer thickness dRK for red light, for each different voltage applied between opposing electrodes. FIG. . Figure 6 is a graph showing the transmittance for each different voltage applied between opposing electrodes for blue light. The graphs shown in Figures 7 and 8 show the transmittance of the liquid crystal display element itself for each part corresponding to each color filter in the on state and off state 1fiK of the liquid crystal display element using the present invention, respectively. Spectral characteristic diagram, No. 9
Figures 1 and 10 are spectral characteristic diagrams showing the transmittance of the liquid crystal display element itself for each part corresponding to each color filter in the on and off states of the liquid crystal display element using the present invention, the 11th factor, and the 11th factor, respectively. Figures 12 and 13 are operational characteristic diagrams showing the transmittance for red, green, and stomach color light, respectively, with respect to the voltage applied to the eye, and Figure 14 is an operation characteristic diagram of the present invention. FIG. 15 is a partial cross-sectional view showing a modified example of , and FIG.
FIG. 6 is an operating characteristic diagram showing the transmittance with respect to the voltage applied to the liquid crystal. DESCRIPTION OF SYMBOLS 11... Lower substrate, 12... Upper substrate, 13... Signal electrode, 14... Footrest electrode, 15... Sealing material, 16
...Liquid crystal, 17...Color filter, 17R...
Red filter, 17G... Green filter, 17B
...Blue filter, 18...HoWJIIJj1.
．． 19.20...Alignment film, 21...Polarized light-like, dR・
...Thickness of the liquid crystal layer in a portion of the red filter, d...Thickness of the liquid crystal layer in a portion of the green filter, dB...Thickness of the liquid crystal layer in a portion of the blue filter. Patent issued and issued by Casio Computer Co., Ltd. (8) Figure 3

Claims (1)

[Claims] (1) A plurality of first and second electrodes arranged intersecting each other on the inner surfaces of a pair of opposing substrates, and corresponding to at least one of the first and second electrodes. a plurality of color filters each colored in at least three primary colors of red, green, and blue;
a liquid crystal interposed between second electrodes, and by sequentially applying a voltage between the first and second electrodes, the first
, in a color liquid crystal display device in which a plurality of dot portions formed at intersections of second electrodes are sequentially driven in a time-division manner, a first dot portion corresponding to each color of the color filter;
The liquid crystal layer for each color interposed between the second electrodes is arranged such that each color is transmitted through the dot portion of each color while a bias voltage of a signal for time division driving is applied between the first and second electrodes. 1. A color liquid crystal display element, characterized in that each layer is formed to have a layer thickness that exhibits a minimum value of transmittance for light of a wavelength of .