JPH02273721A - Color liquid crystal display element - Google Patents

Abstract

PURPOSE:To set the same threshold voltage for respective colors even if color filter films have differences in film thickness with colors by adjusting resistance by varying the width and/or length of wiring connecting electrodes on a substrate and their connection terminals. CONSTITUTION:For example, when liquid crystal layers increase in thickness in the order of G, R, and B, the width of the lead-around wiring 8 which connects transparent conductive films 5 on the sides of scanning electrodes and external connection terminals 9 is increased in the order of G, R, and B corresponding to the differences in thickness between liquid crystal layers to set the resistance of the lead-around wiring 8 in the increasing order of B, R, and G. Consequently, the resistance of the lead-around writing to the scanning electrode of the liquid crystal is high, and consequently a voltage applied to the thin liquid crystal layer B is suppressed because of a voltage drop across the wiring. The resistance of the lead-around wiring to the scanning electrode of the thick liquid crystal layer B, however, is low, the voltage drop across it is small, and a voltage applied to the liquid crystal layer is higher than that at the scanning electrode G. Therefore, voltages applied to the liquid crystal layers by respective color scanning electrodes are different and electric field intensity is equal at the places of the respective color scanning electrodes. Consequently, the threshold voltage of the liquid crystal is not affected by the differences in film thickness with the colors of the color filter films.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a color liquid crystal display element in which a color filter film is formed on the inner surface of a transparent substrate, and even if the thickness of the color filter film differs depending on one color, This element is particularly suitable for STN type color liquid crystal display elements with a small substrate gap, and has the same threshold voltage for all liquid crystal displays regardless of the position of the filter film, that is, the type of color of the filter film formed there. Regarding structure.

[Prior Art] In a conventional dot matrix type large-sized liquid crystal display element, as disclosed in Japanese Patent Application Laid-open No. 117586/1986, the wiring resistance of the transparent conductive films is made equal for each scanning line. This prevents uneven brightness from occurring.

Conventionally, the above-described technology has been used in STN type color liquid crystal display elements, which have been popular in recent years because good contrast can be obtained even when time-divisionally driven with a high duty ratio.

[Problems to be Solved by the Invention] However, color liquid crystal display elements are equipped with color filter films for multiple colors, and the film thickness differs depending on the color due to the manufacturing method. The thickness varies depending on one position, that is, the type of color of the color filter film formed there. In response to this situation, simply making all the wiring resistances of transparent conductive films the same as in the past would result in different colors depending on the color of the color filter formed there, when a voltage is applied to that electrode. The electric field strength generated in the liquid crystal layer differs, which means that the threshold voltage differs depending on the type of color.
Display quality will deteriorate significantly.

The present invention solves the above conventional problems and provides a color liquid crystal display element in which the threshold voltage is the same for each color even if the thickness of the color filter film is different for each color. purpose.

[Means for Solving the Problem] In order to achieve the above object, in the present invention, the liquid crystal layer between the upper and lower substrates is different at each position on the substrate due to the difference in film thickness depending on the color of the color filter film. The resistance is adjusted by changing the width and/or length of the wiring connecting the electrodes at the respective positions on the substrate and their connection terminals in accordance with the thickness of the substrate.
When a voltage is applied between the electrodes that sandwich the liquid crystal layer at each location on the substrate, the electric field strength generated between the electrodes is equal regardless of the location, that is, the type of color of the color filter film formed there. I did it like that.

[Operation] A relatively large capacitance exists between the electrodes of a liquid crystal display element, and the resistivity of the transparent conductive film forming the electrodes is high, so this is a load with a large time constant. When a voltage is applied from the power source to the liquid crystal display element, a charging current flows, and a voltage (W!) between the connecting terminals connected to those electrodes flows between the transparent conductive film electrodes formed on the substrate (W!, from the source to the connecting terminals). The voltage is obtained by subtracting the voltage drop due to the resistance in the transparent conductive film wiring (generally metal wiring has a small voltage drop due to current). Therefore, if the wiring resistance from the connection terminal to the transparent electrode is adjusted to an appropriate value: The resulting display-appropriate voltage differences can be compensated for so that the same electric field strength occurs everywhere on the substrate (at any color location) for the same applied voltage.

Specifically, for places where the color filter film is thick and the liquid crystal layer is thin, the voltage applied to the liquid crystal layer can be lowered by narrowing the wiring width or increasing the resistance by increasing the wiring length. Conversely, in areas where the color filter film is thin and the liquid crystal layer is thick, the voltage applied to the liquid crystal layer is increased by increasing the wiring width or shortening the wiring length to lower the resistance. The electric field strength applied to the liquid crystal layer is made to be the same no matter where the color filter film of any color is formed.

[Embodiment] FIG. 1 is an enlarged sectional view of a main part of an embodiment of the present invention, and FIG. 2 is a top view of the same part of the embodiment. First, a black matrix 2 is placed on the glass substrate 1, and then R, G, and H color filter films 3 are placed between the black matrix 2, and the entire top of these is covered and flattened W! j4, then
A transparent conductive film 5 on the scanning electrode side is formed at positions corresponding to the R2O and B color filter films on the flattening layer 4, and finally an alignment film 6 is formed on both the transparent conductive film 5 and the flattening film 4. Let me.

The cell side surface of the alignment film 6 is subjected to an alignment treatment.

An insulating film may be inserted between the transparent conductive film 5 and the alignment film 6. There is no black matrix, color filter, or flattening layer on the opposing common electrode 7 side.

Here, the thickness of the color filter 3 increases in the order of G>R>B, and the thickness of the liquid crystal layer increases in the order of B>R>G. The thickness of each color filter film is constant depending on the manufacturing method, and the above order is not necessarily true depending on the manufacturing method. Corresponding to the difference in the thickness of the liquid crystal layer shown in FIG. 1, the transparent conductive film 5 on the scanning electrode side and the external connection shown in FIG. ＞I set it to H. In this way, the wiring resistance of the thin G scanning electrode of the liquid crystal layer is high, and the voltage applied to the liquid crystal layer can be suppressed due to the voltage drop there. On the other hand, the wiring resistance of the thick liquid crystal layer to the B scan electrode is low, the voltage drop there is small, and the voltage applied to the liquid crystal layer is higher than that of the G scan electrode.
The voltage applied to the liquid crystal layer is different for each color scan electrode of R, G, and B, and in the end, the electric field strength is equal at each color scan electrode, and the threshold voltage of the liquid crystal depends on the color of the color filter film. Differences in film thickness have no effect. Note that the same applies when the color filter film is attached to the common electrode side.

[Effects of the Invention] As explained above, according to the present invention, the threshold voltage of a color liquid crystal display element (including the case of the STN type with a small cell gap) can be set to the same value for any color. This makes it possible to perform uniform and good color display.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a chestnut portion of an embodiment of the present invention, and FIG. 2 is a top view of the same portion of the same embodiment. 1...Glass substrate, 2...Black matrix,
3... Color filter film, 4... Flattening layer,
5... Transparent conductive film (scanning electrode side), 6... Alignment film, 7... Transparent conductive film (common electrode side), 8... Routing wiring. 9...External connection terminal.

Claims (1)

[Claims] 1. Form a transparent conductive film electrode and a color filter film for multiple colors on opposing inner surfaces in this order or in reverse, form an alignment film and an insulating film thereon, and then form an alignment film and an insulating film on the film. In a color liquid crystal display element, a spacer is interposed between two upper and lower transparent substrates whose innermost surfaces have been subjected to alignment treatment, and a liquid crystal material is filled inside a sealed cell surrounded by a sealing material. Due to the difference in film thickness depending on the color of the film, the thickness of the liquid crystal layer between the upper and lower substrates differs at each position on the substrate. The resistance is adjusted by changing the width and/or length of the wiring connecting the terminals, and when a voltage is applied between the electrodes that sandwich the liquid crystal layer at each position on the substrate, the electric field strength generated between the electrodes is A color liquid crystal display element characterized in that the colors are the same regardless of the type of color filter film formed thereon.