JP2737002B2 - Ferroelectric liquid crystal device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a ferroelectric liquid crystal element applied to, for example, a printer head or a display.

[Prior art] Conventionally, a ferroelectric liquid crystal element used in a printer head or a display is held between a scanning-side electrode group, a matrix electrode including an information-side electrode group that intersects the scanning-side electrode group, and both electrode groups. An image is formed by forming a pixel at each intersection of opposing electrodes and controlling an electric field applied to the liquid crystal at each intersection by a pulse voltage applied to each electrode. It has become. In recent years, attention has been paid to the high-speed response and memory properties of ferroelectric liquid crystals, and development of large-screen flat panel displays using ferroelectric liquid crystal elements is expected.

[Problems to be Solved by the Invention] However, such a ferroelectric liquid crystal (FLC) display is a display using binary pixels that utilizes the white state and black state bistability of the FLC originally packed in a thin cell. For this reason, there is a problem that it is difficult to perform gradation display.

Therefore, a method of arranging an apparent one pixel by a plurality of pixels was considered. In this method, the number of matrix electrodes and the number of driving ICs and the like increase with the number of gradations.
There is a problem that the cost increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a ferroelectric liquid crystal device capable of performing gradation control with a simple and inexpensive configuration in view of the problems of the related art.

[Means for Solving the Problems] To achieve the above object, the present invention provides the following (1) to
(4).

(1) A matrix electrode structure having an information electrode group and a scanning electrode group intersecting and facing the information electrode group, and a ferroelectric liquid crystal held between the two electrode groups. In a ferroelectric liquid crystal element that forms an image by driving a dielectric liquid crystal, the number of information electrodes per pixel is two or more, and each information electrode is an electrode corresponding to an information electrode body and a divided pixel per pixel. A conductor, an insulator, and a non-linear resistor in which the conductor is laminated in this order, and the information electrode main body is connected to the information electrode main body and the electrode portion, respectively. (2) The ferroelectric liquid crystal element, wherein each pixel has a different area, and each pixel is controlled in gradation by a scanning electrode associated with the pixel and an electrode portion of an information electrode associated with the pixel. Each related to pixel The information electrode connects an electrode portion corresponding to two or more divided pixels and the information electrode body and an electrode portion corresponding to the two or more divided pixels corresponding thereto, respectively, a conductor, an insulator, and a conductor. A ferroelectric liquid crystal element according to the above (1), wherein the two or more electrode portions have different inversion thresholds from each other in the one pixel. (4) The information electrode for one pixel is two, and
The ferroelectric liquid crystal element according to (1), wherein each of the information electrodes has two electrode portions.

[Operation] In this configuration, each pixel is controlled to be turned on / off by an electric field between a scan electrode associated with the pixel and an electrode portion of the information electrode associated with the pixel. Since the inversion threshold value of each electrode portion of the device can be made different, by controlling the electric field strength for each information electrode, it is possible to turn on / off any combination of pixel portions.
It is possible to off control, and different areas of all the pixels parts of 1 pixel, thus a data electrode 2 of the pixel for example, if having two electrode portions per each 1 pixel, 2 ⁴ (= 16) Gradation control is performed in gradations.

Reference Example Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a part of a liquid crystal element according to a reference example of the present invention. In the figure, 6 is a glass substrate, 7 is a ferroelectric liquid crystal (FLC), 5 is an upper transparent electrode which is a certain J-th scanning electrode, and 1 and 2 are first information electrodes orthogonal to the upper transparent electrode 5. And the lower transparent electrodes 3 and 4 which constitute a first divided pixel composed of two electrode portions having different areas and inversion thresholds from each other, are also orthogonal to the upper transparent electrode 5 and have a first information electrode. Are connected to the second information electrodes adjacent to each other, and are composed of two electrode portions having different areas and inversion thresholds from each other, and constitute a second divided pixel having a different area from the first divided pixel. Lower electrode. Furthermore, an alignment film layer and an insulating layer are provided on each electrode, but are not shown.
Further, the gaps d ₁ and d ₂ between the upper and lower transparent electrodes 5 and 1 to 4 are different from each other. Therefore, the inversion threshold value of the first divided pixels 1 and 2 or the second divided pixels 3 and 4 is different. Different from each other. The area ratio of the divided pixels is such that the areas of the divided pixels composed of the electrodes 5, 1, 5, 2, 5, 3, 5, and 4 are S ₅₁ , S ₅₂ , S ₅₃ , and S ₅₄ , respectively. S ₅₁ : S ₅₂ : S ₅₃ : S ₅₄ = 4: 1: 2: 3.

FIG. 2 is an explanatory diagram showing each gray scale obtained by combining the on / off states of these divided pixels. It can be seen that ten gradations can be obtained as shown in FIG. However, FIG. 2 shows a case where one pixel is composed of the first divided pixel and the second divided pixel.
Non-hatched portions indicate a white state, and T indicates a gradation level. According to this, for example, as shown in FIG. 2 (c), the left first divided pixel is completely black and the right second divided pixel having a larger area is black. As shown in FIG. 2 (b), since the second divided pixel is completely in a black state and the smaller the area of the first divided pixel is in a black state, the gradation level is different. It is possible to further increase.

Example FIG. 3 is a plan view showing a part of a liquid crystal element according to an example of the present invention. In the figure, 31a is the first information electrode main body, 31b
Is a second information electrode main body, 33a and 33b are first divided pixels, 33c and 33d are second divided pixels, 34 is a first divided pixel including 33a and 33b and second divided pixels 33c and 33d. Pixels, 32
Reference numerals a to 32d denote non-linear resistance portions composed of three layers of a conductor, an insulator, and a conductor. The lower electrodes corresponding to the divided pixels 33a and 33b are connected to the first information electrode main body 31 through the non-linear resistance portions 32a and 32b.
The lower electrode corresponding to the divided pixel 33c, 33d is connected to the second information electrode main body 31b via the non-linear resistance portions 32c, 32d. The area ratio of the divided pixels 33a to 33d is 4: 2 to 8: 1.

In particular, this embodiment is characterized in that a voltage is applied to each of the divided pixels 33a to 33d via the non-linear resistors 32a to 32d.

Here, since the divided pixels 33a to 33d have different areas, the capacitances are also different from each other. In particular, when the capacitance and breakdown voltage of the non-linear resistance portions 32a to 32d are the same, the divided pixels have different inversion thresholds. . Of course, if the capacitances of the divided pixels 33a to 33d, the capacitances of the nonlinear resistance portions 32a to 32d, and the breakdown voltage are appropriately set, the inversion threshold of the divided pixels can be set to a desired value.

Therefore, with the configuration as shown in FIG. 3, a ferroelectric liquid crystal display having pixels of 2 ⁴ = 16 gradations can be obtained in the same manner as shown in FIG.

[Effects of the Invention] As described above, according to the present invention, for each pixel,
A plurality of information electrodes having a plurality of electrode portions having different threshold values from each other are provided, and these electrode portions have different areas, so that the number of gradations can be increased without increasing the number of matrix electrodes and the number of driving ICs. Further, a ferroelectric liquid crystal element can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a part of a liquid crystal element according to a reference example of the present invention, FIG. 2 is an explanatory view showing each gradation obtained by combining the on / off states of each divided pixel, and FIG. FIG. 1 is a plan view showing a part of a liquid crystal element according to an embodiment of the present invention. 1-4: lower transparent electrode, 5: upper transparent electrode 6: glass substrate, 7: ferroelectric liquid crystal, 31a, 31b: information electrode body, 32a-32d: non-linear resistance part, 33a-33d: divided pixel, 34: 1 pixel.

Claims (4)

(57) [Claims] A matrix electrode structure having an information electrode group and a scanning electrode group intersecting the information electrode group; and a ferroelectric liquid crystal held between the two electrode groups, and applying a voltage between the two electrode groups. In a ferroelectric liquid crystal element that forms an image by driving a ferroelectric liquid crystal, two or more information electrodes per pixel are provided.
For each pixel, an information electrode main body, an electrode portion corresponding to a divided pixel, and a non-linear resistor in which a conductor, an insulator, and a conductor are stacked in this order to connect the information electrode main body and the electrode portion with each other. The electrode portion of each information electrode has a different area for one pixel, and each pixel is controlled in gradation by the scanning electrode of the pixel and the electrode portion of the information electrode of the pixel. Characteristic ferroelectric liquid crystal element. 2. Each information electrode of one pixel connects an electrode portion corresponding to two or more divided pixels and an information electrode main body and an electrode portion corresponding to the two or more divided pixels, respectively. 2. The ferroelectric liquid crystal device according to claim 1, further comprising a non-linear resistor in which a conductor, an insulator, and a conductor are laminated in this order. 3. The ferroelectric liquid crystal device according to claim 2, wherein in one pixel, the two or more electrode portions have mutually different inversion thresholds. 4. The ferroelectric liquid crystal element according to claim 1, wherein the number of information electrodes per pixel is two, and each of the two information electrodes has two electrode portions.