JP2001356281A - Display element and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide display elements of a plane type which may be inexpensively manufactured with simple constitution, are capable of efficiently utilizing light source light for display, are high in luminance and wide in visual field angles and are capable of making with sufficient contrast without the occurrence of light leakage and color mixing and a display device. SOLUTION: The display device has the plural display elements, a light source and a light transmission plate for reflecting the light source light and introducing this light to the display elements. The display elements have substrates having display windows serving to be pixels and shutter elements 7 having, for example, flexibility. The shutter elements 7 are piezoelectric elements having the bimorph structures formed by piezoelectric films. The shutter elements 7 shut off the light source light by closing the display windows in an ordinary state and on the other hand, when electric fields are impressed thereto, the shapes of the shutter elements 7 are curved (deformed) by the piezoelectricity of the piezoelectric films to open the display windows, by which the light source light is transmitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display element having a substrate on which a display window to be a pixel is formed and an opening / closing member for opening and closing the display window, and a display device having the display element. is there.

[0002]

2. Description of the Related Art A liquid crystal display element is well known as a display element having a flat shutter for displaying by transmitting or blocking (modulating) light emitted from a light source. In a liquid crystal display element, by applying an electric field (voltage) to liquid crystal, the liquid crystal is used as a flat shutter (light shielding member) to transmit or block light. A liquid crystal display device provided with the element has been widely used as a flat display such as a personal computer monitor, a mobile device, and a TV monitor.
Display is performed by independently driving a large number of fine pixels formed in a matrix by combining with an active matrix element.

As a flat shutter of a display element, a piezoelectric element having a bimorph structure is known.
For example, M. Toda, S. Osaka, Proc.SID, 19, 35 (1
978) has a pair of substrates, a display window is formed on one substrate, and the piezoelectric element is mounted on the other substrate in a direction perpendicular to the substrate (toward one substrate). A type display element is disclosed. The piezoelectric element is painted in different colors on the front surface and the rear surface, and a black colored plate (hereinafter referred to as a blackboard) for opening and closing the display window is provided at the tip of the piezoelectric element. (So as to be parallel to one of the substrates). In the segment type display element having the above configuration, an electric field (voltage) is applied to the piezoelectric element.
To cause the piezoelectric element to bend, thereby displaying the colored front or back surface in a display window,
The display window is hidden by the blackboard when an electric field is not applied while displaying by light reflection.

In Japanese Patent No. 2599886, a movable member that moves in parallel by static electricity is provided on a substrate, and an opening / closing plate (flat shutter) attached to the movable member is provided.
There is disclosed a flat display element that opens and closes a display window by moving in parallel between a display window formed on a substrate and a light-shielding portion, thereby performing display. The movable element is not fixed when no electric field is applied.

[0005]

However, for example, in a liquid crystal display element, a polarizing plate is used, so that the polarizing plate blocks a part of the light, and the light emitted from the light source ( Hereinafter, it is referred to as light source light).
%. Therefore, in the liquid crystal display element, only about several percent of the light source light can be used for display, considering the transmittance of the substrate and the like. Therefore, even when the liquid crystal is in a bright state in which light is transmitted, the brightness of the light from the light source is not sufficiently reflected on the display. Further, even in the dark state due to the crossed Nicols of the polarizing plate, light is leaked, so that a completely black display is not obtained. Further, the liquid crystal display element has various problems that a viewing angle of a liquid crystal display device using the element is narrowed in principle because the appearance of display is changed by switching of liquid crystal. I have. In recent years, measures have been taken to improve the viewing angle of the liquid crystal display device, and therefore the viewing angle has become very wide. However, since the number of manufacturing steps for taking the countermeasure is increased, another problem occurs that the cost of the liquid crystal display device is increased.

[0006] On the other hand, for example, in a segment type display element using a piezoelectric element, a blackboard attached to the piezoelectric element and a substrate on which a display window is formed are not in contact with each other. Therefore, even if the display window is hidden by the blackboard, a gap is generated between the blackboard and the display window in principle, so that light leakage or color mixing occurs. That is, in a display device using the element, display cannot be performed with sufficient contrast. Further, vertically mounting a piezoelectric element on a substrate is structurally difficult to manufacture, and is not suitable for miniaturization of a display element. In other words, a display device using the element has various problems that it is suitable for large segment display, but is not suitable for a display for displaying information.

In a display element using an opening / closing plate, the display window is opened / closed by the parallel movement of the opening / closing plate. Therefore, a light shielding portion having at least the same size as the display window is required in terms of structure. Therefore, in the display element, the ratio of the display window to the substrate (aperture ratio) becomes extremely small (at least less than half) in consideration of providing a wiring portion and the like necessary for driving the movable element, and the light source light Only about a few percent of them (at least less than half) are available for display. Further, the movable element is not fixed when no electric field is applied. For this reason, when no electric field is applied, when vibration is applied to the display element, or when the display element is moved, there is a possibility that the moving element may shift or drop off from a predetermined position. That is, the display element
Function cannot be performed stably. In addition, since a complicated semiconductor process is required to make the structure capable of supporting and driving the moving element, the yield of the display element is low and the display element is not suitable for increasing the size. That is, there are various problems that a display element exhibiting stable performance cannot be manufactured with good reproducibility and high yield.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to be able to manufacture at a low cost with a simple configuration and to efficiently display light emitted from a light source. A flat display element that can be used for high brightness, has a wide viewing angle, and can perform display with sufficient contrast without causing light leakage and color mixing, and the display element Provided is a display device having the same.

[0009]

In order to solve the above-mentioned problems, a display element of the present invention has a substrate on which a display window to be a pixel is formed, and emits light from a light source by opening the display window. An opening / closing member that transmits light and closes the display window to shut off light to perform display by closing the display window, wherein the opening / closing member is provided on the one substrate; It is characterized in that the display window is opened and closed by deforming its shape.

According to the above configuration, the display window is opened / closed by deforming the shape of the opening / closing member, so that the ratio of the display window to the substrate (opening ratio) can be increased. Further, as compared with a liquid crystal display element using two substrates and liquid crystal, the configuration is simple and the number of manufacturing steps is small. Unlike a liquid crystal display device or the like, since it is not provided with an optical device such as a polarizing plate or a retardation plate, light emitted from a light source can be efficiently used for display, and has high luminance and high visual field. The corners are wide and light leakage and color mixing do not occur. Therefore,
A flat display element capable of performing display with a sufficient contrast can be provided.

In order to solve the above-mentioned problems, the display element of the present invention is characterized in that the substrate has flexibility. According to the above configuration, it is possible to obtain a (curved surface) display element that can support display on a curved surface portion.

A display device according to the present invention includes the above-described display element in order to solve the above-mentioned problems. According to the above configuration, since the configuration of the display element is simple, it is easy to increase the size of the display device, and it is possible to provide a display device suitable as a display of a mobile device or the like for displaying information. .

[0013]

[Embodiment 1] An embodiment of the present invention will be described with reference to FIGS.
It is as follows. In the following description, a display device employing a side backlight system will be described as an example.

The display device according to the present embodiment employs a side backlight system. As shown in FIG. 2, a plurality of display elements 1, a light source 2 as a side backlight, and a light source 2 are provided. And at least a light guide plate 3 that reflects light emitted from the light source (hereinafter referred to as light source light) and guides the light to the display elements 1. As the light source 2, specifically, for example, a cold cathode tube used for a liquid crystal display device or the like,
An L lamp or the like is suitable, but is not particularly limited as long as it is a light source having excellent light generation efficiency and a long life.

The display element 1 has a structure formed by one substrate, and employs a so-called flat shutter system. As shown in FIG. 1, the display element 1 includes a substrate 5 having a display window 6 to be a pixel, and a (flexible) shutter element (open / close member) having flexibility, for example.
7 is provided.

The substrate 5 is made of a transparent insulating material, and while the display window 6 is kept in a transparent state, a region other than the display window 6 on the substrate 5 (hereinafter, referred to as a light shielding portion) is, for example, Light-shielding properties are imparted by employing a printing method or a photolithography method. Therefore, the display window 6 transmits the light from the light source, while the light blocking portion shields the light from the light source. The size of the pixel, that is, the size of the display window 6 is not particularly limited. For example, when the display device is used as a display of a mobile device or the like, the size is 300 μm × 30 μm.
About 0 μm is preferable. As a material of the substrate 5, glass or a hard plastic may be used, or a plastic having flexibility (flexible) may be used. When the substrate 5 is formed by using a plastic having flexibility, external force can be absorbed by the flexibility, so that the substrate 5 is strong against impact, durable, and can correspond to display on a curved surface portion. The display element 1 (of a curved surface type) can be obtained, and a so-called realistic display can be performed. That is, a display device provided with the display element 1 is suitable as a display of a mobile device or the like for displaying information.

The shutter element 7 is, as shown in FIG.
For example, a piezoelectric film 9.9 made of a functional material (engineering plastic) such as a polyvinylidene fluoride (PVDF) polymer having piezoelectricity is provided on both sides of an elastic plate 8 made of rubber or the like by using an adhesive or the like. It has a three-layer structure formed by sticking. That is, the shutter element 7 is a piezoelectric element having a bimorph structure formed of a piezoelectric film. Of the two piezoelectric films, the surface of the piezoelectric film 9 located on the display window 6 side is colored black in order to obtain a sufficient contrast, or black by adding a coloring agent to the functional material. It is colored. On the other hand, the piezoelectric film 9 located on the back side with respect to the display window 6 has, for example, a reflection film or a diffusion film formed on its surface by a predetermined method in order to effectively use light from the light source. Note that the shutter element 7 is not particularly limited as long as it has a configuration capable of opening and closing the display window 6 by deforming its shape.

The shutter element 7 is provided on the substrate 5, specifically, on the back side of the substrate 5, and opens and closes the display window 6 by deforming its shape. That is, a pair of electrodes are electrically connected to the piezoelectric film 9 of the shutter element 7 as described later, and when an electric field (voltage) is applied between these electrodes, the piezoelectric film 9.
9, that is, the shutter element 7 bends and opens the display window 6. More specifically, as shown in FIG. 1A, in a normal state, the light source light is blocked by closing the display window 6, and when an electric field is applied, for example, as shown in FIG. In addition, the shape of the shutter element 7 is curved (deformed) by the piezoelectricity of the piezoelectric films 9, 9, and the display window 6 is opened, so that light from the light source is transmitted. Therefore, when the display window 6 is closed, black display is performed by the shutter element 7, and when the display window 6 is open, white display is performed by light from the light source.

As described above, since the shutter element 7 has a configuration in which the display window 6 is opened by deforming its shape, it is compared with, for example, a display element in which the display window is opened by moving the opening / closing plate in parallel. Thus, the size of the light-shielding portion can be reduced. Therefore, the ratio (opening ratio) of the display window 6 to the substrate 5 can be increased,
The light from the light source can be efficiently used for display.

The thickness of the piezoelectric film 9 is not particularly limited, but is preferably about 0.5 μm. When the length of the piezoelectric film 9 is L, the thickness is t, the piezoelectric constant is d, and the voltage is V, the displacement amount δ of the piezoelectric film 9 is as follows: δ = (3/4) d · (L / t) is represented by ² V. Therefore, since the displacement δ is proportional to the voltage V, the displacement δ can be adjusted by adjusting the height of the voltage V. That is, the shutter element 7
By adjusting the height of the voltage applied to the piezoelectric film 9, the amount of deformation (the degree of deformation) of the shape can be appropriately adjusted. Therefore, the shutter element 7
The amount of light transmitted through the display window 6 (the amount of transmitted light)
Since the modulation (adjustment) can be performed, the display element 1 can perform gradation display.

Although the display element 1 is a monochrome display element, the display element 1 may be a color display element by attaching a color filter to the display window 6, for example. The method for forming the display window is not particularly limited. For example, the display window 6 may be formed by hollowing out a part of the substrate 5. Further, the method for forming the light-shielding portion is not particularly limited. For example, the light-shielding portion may be formed by adding a coloring agent such as a pigment or a dye to a transparent material so as to be colored black. In short, the substrate 5
It suffices if the display window 6 has a configuration in which the light source light is transmitted and the light shielding portion shields the light source light.

As a method of deforming the shape of the shutter element 7, for example, a method of applying an electric field, a writing method using light different from light from a light source, and the like can be mentioned. More specifically, as a method of deforming the shape of the shutter element 7, as shown in FIG. 4A, a method of performing a bending motion by applying an electric field using a piezoelectric element having a bimorph structure ( That is, the method described above), or a method in which an element having a bimorph structure is used to cause a bending movement by thermal expansion; and a method in which the element is bent and moved by static electricity as shown in FIG. As shown in (d), a method of expanding and contracting (deforming) in the thickness direction by applying an electric field using a piezoelectric element having a laminated structure; a piezoelectric element or a polymer as shown in FIG. A method of contracting and expanding the volume of the element using an element made of gel; and a method of deforming the shape of the element using an element made of a shape memory material as shown in FIG. Listed But it is not particularly limited.

A more detailed structure of the display element 1 including the substrate 5 and the shutter element 7 will be described below. As shown in FIGS. 5 and 6, the display element 1 includes a plurality of electrodes 11 formed in parallel and a plurality of electrodes 12 formed in parallel on the back side of the substrate 5. The two electrodes 11... 12 are formed by attaching paste-formed nickel to the back side of the substrate 5 by using, for example, a printing method and drying the paste sufficiently. Both electrodes 11 ...
Are orthogonal to each other, and the respective intersections are insulated from each other by an insulating resin layer 13. Also, at a predetermined position of the electrode 11, a conductive wire portion 1 for electrically connecting the piezoelectric film 9 of the shutter element 7 and the electrode 11 is provided.
1a is formed.

The electrode 11, that is, the conductor 11a is
The display window 6 is provided via a conductive layer 14a made of a conductive adhesive.
The electrode 12 is electrically connected to the piezoelectric film 9 via a conductive layer 14b made of a conductive adhesive.
That is, the electrodes 11 and 12 are electrically connected to the same piezoelectric film 9. Therefore, the shutter element 7 is attached to the substrate 5 via the conductive layers 14a and 14b and the electrodes 11 and 12. The electrode 11
The shape, connection position, and the like of... 12 may be set so as to be the optimum shape, connection position, and the like according to the configuration and shape of the shutter element 7 used. Also, the electrodes 11... 1
2 are formed in the light-shielding portion and need not be transparent.

The display element 1 having the above-described configuration is, for example,
After attaching the piezoelectric films 9.9 to both surfaces of the elastic plate 8 to form the shutter element 7 and forming the substrate 5 having the display window 6 by a predetermined method, the electrodes 11,.
The insulating resin layer 13 and the electrodes 12 are formed in this order,
Next, the conductive layers 14a are provided at predetermined positions of the electrodes 11 ... 12.
It can be easily manufactured by applying the conductive adhesive to be 14b and attaching the shutter element 7.

Therefore, the manufacturing process of the display element 1 is different from the manufacturing process of a liquid crystal display element using two substrates and liquid crystal, for example, in the step of attaching the two substrates to each other, Since a step of injecting liquid crystal into the substrate is not required, the configuration is very simple and the number of manufacturing steps is small. That is, the display element 1 can be manufactured at low cost by a simple manufacturing process. The method for manufacturing the display element 1 is not particularly limited.

The display element 1 according to the present embodiment is different from a liquid crystal display element or the like in that it does not include an optical element such as a polarizing plate or a retardation plate. For this reason, the display element 1 has a wide viewing angle, does not cause light leakage or color mixing, and
It does not depend on the frequency characteristics of the light source 2. Further, for example, in a liquid crystal display device, the light transmittance of the liquid crystal panel is about several percent, whereas the display elements 1 according to the present embodiment are arranged.
In the display device provided with (1), the cause of the decrease in the light transmittance of the panel is mainly the light absorption and the aperture ratio of the display window 6 in the substrate 5, and the transmittance is as high as 60 to 70%. Therefore, the light source light can be efficiently used for display, and a display device with high luminance can be obtained.
Therefore, it is possible to provide a flat display element capable of performing display with sufficient contrast.

In the above description, the case where the shutter element 7 is provided on the back side of the substrate 5 has been described as an example, but the shutter element 7 may be provided on the front side of the substrate 5. Alternatively, when the display window 6 is formed by hollowing out a part of the substrate 5, the shutter element 7
May be provided so as to fit into the hollowed portion. That is, the shutter element 7 only needs to be attached to the substrate 5.

As described above, the display element 1 according to the present embodiment can be manufactured at a low cost with a simple configuration, can use the light source light efficiently for display, and has a high luminance. It is a flat display element that is high in viewing angle, wide in viewing angle, and capable of performing display with sufficient contrast without causing light leakage or color mixing. The display device according to the present embodiment has a display element 1 having a simple configuration.
Therefore, it is easy to increase the size and is suitable as a display of a mobile device or the like for displaying information.

In the above description, a display device employing a side backlight system has been described as an example, but the display device may have a configuration employing an entire backlight system. The display element can also use sunlight as a light source (backlight), for example, by being attached to a glass window or the like. Alternatively, the display element is
For example, it can be used as a simple reflective display element (display) by placing it on a light reflecting plate or a light diffusing plate, or on white paper or a desk. Also in this case, the display using the display element according to the present invention can use the light from the light source for display more efficiently than the display using the liquid crystal display element.

[0031]

According to the display element of the present invention, as described above, the opening / closing member is provided on one substrate on which the display window is formed.
Further, the opening / closing member is configured to open and close the display window by deforming its shape.

Thus, the ratio of the display window to the substrate (opening ratio) can be increased. Moreover, since it has a simple configuration and has few manufacturing steps, it can be manufactured at low cost. Then, the light emitted from the light source can be efficiently used for display, the luminance is high, the viewing angle is wide, and light leakage and color mixing do not occur. Therefore, there is an effect that a flat display element capable of performing display with sufficient contrast can be provided.

As described above, the display element of the present invention has a structure in which the substrate has flexibility. Thereby, there is an effect that it is possible to obtain a (curved surface) display element that can support display on a curved surface portion.

As described above, the display device of the present invention has a configuration including the above-described display element. Accordingly, since the configuration of the display element is simple, it is easy to increase the size of the display device, and it is possible to provide a display device suitable as a display of a mobile device or the like for displaying information. .

[Brief description of the drawings]

FIGS. 1A and 1B show a schematic configuration of a display element according to an embodiment of the present invention, in which FIG. 1A is a cross-sectional view showing a state in which a display window is closed by a shutter element, and FIG. It is sectional drawing which shows the state in which the display window was opened by bending motion.

FIG. 2 is a side view illustrating a schematic configuration of a display device including the display element.

FIG. 3 is a perspective view showing a schematic configuration of the shutter element.

FIGS. 4A to 4E are perspective views showing various modifications of the shutter element.

FIG. 5 is a plan view showing a schematic configuration of the display element.

FIG. 6 is a sectional view showing a schematic configuration of the display element.

[Explanation of symbols]

 Reference Signs List 1 display element 2 light source 5 substrate 6 display window 7 shutter element (opening / closing member) 9 piezoelectric film

Claims (3)

[Claims] 1. A display device comprising: a substrate having a display window to be a pixel; a light emitted from a light source being transmitted by opening the display window; and a light being blocked by closing the display window. A display element having an opening / closing member for performing the operation, wherein the opening / closing member is provided on the single substrate, and the opening / closing member is configured to open and close the display window by deforming its shape. Display element. 2. The display element according to claim 1, wherein said substrate has flexibility. 3. A display device comprising the display element according to claim 1.