KR100696261B1 - Transmission Type Display Device Using Micro Light Modulator - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive display device using a fine optical modulator in which an optical path converting member is configured to present an optimal condition of an optical path converting member for bending an incident light incident at an oblique angle in a direction perpendicular to a display surface.

The transmissive display device using the fine optical modulator according to the present invention includes an optical path converting member installed on the fixing member and configured to convert a path of light incident obliquely between the fixing members and the movable members in a direction perpendicular to the display surface. The angle of the incident surface formed on one side of the optical path changing member is determined to be at least 52 ° based on the display surface.

Description

Transmission type display device using micro light modulator             

1A and 1B are cross-sectional views illustrating a transmissive display device using a conventional fine optical modulator.

2 is a cross-sectional view illustrating a front substrate and a rear substrate structure of the display device illustrated in FIGS. 1A and 1B.

3 is a cross-sectional view illustrating an optical path changing member installed in a transmissive display device using the fine optical modulator shown in FIGS. 1 and 2.

4A is a cross-sectional view illustrating widths, spacings, and overlapping widths of electrode patterns in a transmissive display device using a fine optical modulator according to an exemplary embodiment of the present invention.

4B is a cross-sectional view illustrating the inclination angle, the height, and the base of the light path changing member illustrated in FIG. 4A.

5A is a characteristic diagram showing a direction distribution of light sources used in a simulation in a transmissive display device using a fine optical modulator according to the present invention;

FIG. 5B shows the distribution of the emitted light of the light sources used for the simulation of the uniaxial direction of the electrode when 0 ° is determined when the exit light is perpendicular to the display surface in the transmissive display device using the fine optical modulator according to the present invention. drawing.

FIG. 6 is a characteristic diagram illustrating output light distribution according to a change in the inclination angle of the light path conversion member when the light source 1 shown in FIG. 5A is applied as a simulation light source. FIG.

FIG. 7 is a characteristic diagram showing the emitted light distribution of the light sources shown in FIG. 5A when the inclination angle of the light path conversion member is 55 °. FIG.

FIG. 8 is a characteristic diagram showing the emitted light distribution of the light sources 2-8 shown in FIG. 5 when the inclination angle of the light path changing member is changed from 2.5 to 55 degrees at an interval of 47.5 degrees.

9 is a characteristic diagram illustrating distribution of emitted light according to changes in size and spacing of electrode patterns constituting the MEMS panel illustrated in FIG. 4A.

FIG. 10 is a characteristic diagram illustrating output light distribution according to a change in overlap width between an upper movable electrode and a lower fixed electrode constituting the MEMS panel shown in FIG. 4A.

FIG. 11 is a characteristic diagram illustrating an emission light distribution of the light source 1 according to a change in overlap width between an upper movable electrode and a lower fixed electrode constituting the MEMS panel shown in FIG. 4A.

12 is a characteristic diagram showing the distribution of emitted light according to the height change of the optical path changing member.

<Description of Symbols for Main Parts of Drawings>

11: upper movable electrode 12: lower fixed electrode

13: back substrate 14: back light

20: light path conversion member 30: MEMS panel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display element for displaying an image by modulating a light beam. In particular, the present invention proposes an optimal condition of a light path conversion member in an optical path conversion member for bending an incident light incident at an oblique angle in a direction perpendicular to the display surface. The present invention relates to a transmissive display device using a fine optical modulator.

As a next generation display device, research on various flat panel display devices has been actively conducted. Such flat panel display devices include liquid crystal displays (hereinafter referred to as "LCDs") that have been generalized, and plasma display panels (hereinafter referred to as "PDPs") using gas discharge. The LCD has a narrow viewing angle and a slow response time, and the manufacturing process is complicated because it forms a thin film transistor (TFT) and an electrode, which are switching elements, in the semiconductor manufacturing process. PDP is advantageous for large area due to its simple manufacturing process, but has a disadvantage in that discharge and luminous efficiency are low and expensive.

Accordingly, the development of a new display device that can solve the problems of the flat panel display device is in progress. Recently, a transmission type display device capable of displaying an image by forming a fine optical modulator for each pixel cell using a micro electromechanical system (hereinafter, referred to as "MEMS") has been proposed. have.

Referring to FIGS. 1A and 1B, a transmissive display device using a fine optical modulator includes lower fixed electrodes 12 formed side by side on a substrate 13 at predetermined intervals, and lower fixed electrodes in response to a voltage signal. The upper movable electrode 11 overlaps with both sides of the (12). The lower fixed electrodes 12 are formed in a strip shape on the substrate 13. Both ends of the upper movable electrodes 11 are fixed on the substrate 13, and a central portion thereof rises from the substrate 13 by a predetermined distance. These lower fixed electrodes 12 and the upper movable electrodes 11 are controlled by an electrical signal to serve to open and close the optical path by an electrostatic force interacting according to the display state and the non-display state.

In a non-display state as shown in FIG. 1A, a voltage of a predetermined level is applied to the lower fixed electrodes 12 and the upper movable electrodes 11. Then, since the attraction force by the electrostatic force is applied to the lower fixed electrodes 12 and the upper movable electrodes 11, the upper movable electrodes 11 are in contact with the adjacent lower fixed electrodes 12. In this case, the lower pinned electrodes 12 and the upper movable electrodes 11 block light incident from the back light provided on the rear surface of the substrate 13.

On the contrary, in the display state as shown in FIG. 1B, no voltage is applied to the lower fixed electrodes 12 and the upper movable electrodes 11. Then, the upper movable electrodes 11 are returned to their original state by their elastic restoring force, and thus are lifted from the substrate 13 and the lower fixed electrodes 11. In this case, an optical path is formed between the lower fixed electrodes 12 and the upper movable electrodes 11. Light incident from the backlight is transmitted through the optical path toward the display surface to display an image or an image.

However, in the display device shown in FIGS. 1A and 1B, since the incident light is transmitted at an angle (60 to 80 °) inclined through the optical path between the lower fixed electrodes 12 and the upper movable electrodes 11, the display element of FIG. It is necessary to adjust the incident light propagating toward the viewer viewed from the front perpendicular to the substrate. To this end, one reverse prism sheet and one diffusion sheet are laminated on the front substrate (not shown), or as shown in FIG. 2, the diffusion sheet 16c, the horizontal prism sheet 16a, and the vertical prism sheet ( 16b) and the diffusion sheet 18 are laminated on the front substrate.

In order to solve the problems caused by the inclination angle of the incident light incident on the front substrate, the applicant of the Korean Patent Application No. 99-55025 discloses a light path converting member that bends the incident light in a direction perpendicular to the display surface. It has been proposed to install between the boards. The optical path converting member has a trapezoidal cross section as shown in FIG. 3, and the incident light is bent in a direction perpendicular to the display surface, thereby increasing the efficiency of light passing through the display surface without a separate prism sheet.

However, the optical optimum conditions of the trapezoidal optical path converting member need to be presented in order to bend the incident light which is incident obliquely and perpendicularly to the display surface.

Accordingly, an object of the present invention is to provide a transmissive display device using a fine optical modulator to present an optimal condition of an optical path converting member in an optical path converting member for bending an obliquely incident incident light in a direction perpendicular to the display surface. It is.

In order to achieve the above object, the transmissive display element using the micro-light modulator according to the present invention is installed on the fixing member to convert the path of the light incident obliquely between the fixing members and the movable members in a direction perpendicular to the display surface. An optical path converting member is provided, and the angle of the incident surface formed on one side of the optical path converting member is determined to be at least 52 ° based on the display surface.
The light path converting member is made of a material having high reflectivity.
The cross section of the light path conversion member is characterized in that the trapezoid.
The angle of the incident surface formed on one side of the light path converting member is determined at any angle between 52 ° and 70 ° based on the display surface.
The light path converting member is formed at a height greater than a distance between the fixing members and the movable members.
The bottom side of the optical path changing member is determined to be smaller than the distance between the movable members.

Other objects and features of the present invention in addition to the above object will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 4 to 12.

4A and 4B, the MEMS panel 30 of the transmissive display device using the fine optical modulator according to the present invention is formed on the substrate 13 and the upper movable electrodes 11 to open and close the optical path by electrostatic force. And a lower fixed electrode 12 and a trapezoidal light path converting member 20 formed on the lower fixed electrode 12 to bend the light incident obliquely in a direction perpendicular to the display surface.

In the MEMS panel 30, the electrode width of the upper movable electrodes 11 is "a", the width between the upper movable electrodes 11 is "b", and the electrode width of the lower fixed electrodes 12 is "c". And a distance between the lower fixed electrodes 12 is "d". The overlap width at which the right side of the upper movable electrode 11 and the left side of the lower fixed electrode 12 overlap is "x1", and the left side of the upper movable electrode 11 and the right side of the lower fixed electrode 12 overlap. Assume the overlap width is "x2". The inclination angle t formed between the incident surface and the bottom surface of the trapezoidal optical path changing member 20 according to the size (width) and the spacing of the electrode patterns folds the incident light in a direction perpendicular to the display surface and the MEMS panel 30 is rotated. The angle must be changed so that the distribution of the light passing through has a symmetrical structure with respect to the front face.

The trapezoidal optical path is fixed when the distance T between the upper movable electrodes 11 and the lower fixed electrode 12 is fixed to 2.5 μm, and when a = 12 μm, b = 8 μm, c = 12 μm, d = 8 μm, and x1 = x2 = 2 μm. The optimal tilt angle t of the converting member 20 is determined based on the following simulation.

FIG. 5A illustrates a profile representing a direction distribution of light sources used for simulation. In FIG. 5A, the horizontal axis represents the inclination angle of the emitted light when the light passing through the MEMS panel 30 is perpendicular to the display surface, and the vertical axis represents the luminance. Here, the light source 1 is a back light composed only of a lamp assay, a reflective sheet, and a patterned light guide plate. The light sources 2-1 to 2-8 are light sources in which the direction of the emitted light is changed by a predetermined angle with respect to the light source 1.

6 shows the distribution of the emitted light by the change of the inclination angle t formed between the incident surface and the bottom surface of the light path conversion member 20 when "light source 1" is used as the simulation light source. Here, the height f and the base side e of the trapezoidal light path converting member 20 are fixed at 4 μm and 8 μm, respectively, and the inclination angle t is changed at intervals of 2.5 ° from 45 ° to 60 °. As can be seen from FIG. 6, when the inclination angle t is 55 °, the outgoing light of the light source 1 is symmetric with respect to the vertical direction of the display surface.

FIG. 7 is a simulation result when the tilt angle is 55 ° with respect to various light sources used in FIG. 5A when the height f and the base e of the trapezoidal light path converting member 20 are fixed to 4 μm and 8 μm, respectively. In FIG. 7, when the light passing through the MEMS panel 30 is perpendicular to the display surface, the light source having the highest luminance value and the highest luminance value are shifted the most from the angle (0 °) perpendicular to the display surface. Only the light sources (light sources 2-4 and 2-8). "Light sources 2-4" appear in the outgoing light with the highest brightness value of + 4 °, and "Light sources 2-8" appear in the outgoing light with the highest brightness value of -7 °.

On the other hand, in Figure 7, the side lobe (side lobe) is a high luminance value near the angle of the emitted light is approximately 50 °, the light passing through the electrodes (11, 12) of the MEMS panel 30 is highly reflective and electrical It indicates light that passes directly through the display surface without being reflected by the light path converting member 2 made of a conductive metal.

As can be seen in FIG. 7, the inclination angle t of the trapezoidal optical path converting member 20 is adjusted with respect to the output light shifted in the + direction or the − direction with the highest luminance value 0 ° to the optical path converting member 20. By adjusting the angle of the light reflected by the highest luminance value can be appeared at 0 °. For example, when the highest luminance value is shifted in the − direction at 0 °, the inclination angle t of the optical path converting member 20 is adjusted to be smaller than 55 °, while when shifted in the + direction, the optical path converting member 20 is adjusted. By adjusting the inclination angle t of greater than 55 °, the highest luminance value can be displayed on the 0 ° side.

FIG. 8 shows the light distribution of the "light source 2-8" when the inclination angle t of the trapezoidal light path changing member 20 is changed from 47.5 ° to 55 ° by 2.5 ° intervals. As can be seen from FIG. 8, "light source 2-8" indicates that the outgoing light distribution is in the + and-directions about an angle (0 °) where the inclination angle t of the light path conversion member is perpendicular to the display surface at approximately 52.5 °. Is symmetrical in. Similarly, as a result of simulating under the same conditions for all the light sources used in FIG. 5A, the trapezoidal light path converting member is required to make the distribution of the emitted light symmetrical in the + direction and the-direction with respect to the vertical direction of the display surface. The inclination angle t shall be determined between approximately 52 ° and 59 °.

In the case of using a back light composed of only a lamp assay, a reflective sheet, and a patterned light guide plate as a light source 1 as a light source for the MEMS panel 30, the size and spacing of the electrode patterns constituting the MEMS panel 30 are shown in the table below. When changed as shown in FIG. 1, the highest luminance value of the emitted light passing through the display surface is present within a range of ± 3 ° based on an angle perpendicular to the display surface, that is, 0 °, as shown in FIG. 9. At this time, when the inclination angle t of the optical path changing member 20 is fixed and the bottom side e of the trapezoidal optical path converting member 20 and the upper movable electrode 11 are simulated under the same conditions, when the light source 1 is used. The inclination angle t of the light path converting member 20 symmetrical in the + direction and the − direction and the highest luminance value of the emitted light appears perpendicular to the display surface (0 °) should be determined at an angle between approximately 52 ° and 58 °.

a: b: c: d x1: x2 8: 6: 8: 6 1: 1 10: 6: 10: 6 2: 2 10: 8: 10: 8 1: 1 12: 8: 12: 8 2: 2 12: 10: 12: 10 1: 1 14: 10: 14: 10 2: 2

Subsequently, when a light source 1 composed of only a lamp assay, a reflective sheet and a patterned light guide plate is applied as a light source of the transmissive display device according to the present invention, and the inclination angle t of the trapezoidal optical path changing member 20 is determined to be 55 ° and the electrode pattern Changes in the overlap widths x1 and x2 of the upper movable electrodes 11 and the lower fixed electrodes 12 when the size (width) and the distance of the electrodes are fixed to a = 12 μm, b = 8 μm, c = 12 μm, and d = 8 μm As a result, the condition for the inclination angle t of the light path conversion member 20 is determined so that the light emitted from the light source 1 emits the display surface at an angle perpendicular to the display surface.

Referring to FIG. 10, when the inclination angle t of the trapezoidal optical path converting member 20 is 55 °, the height f is 4 μm, and the base e is 8 μm, the emission light distribution of the light source 1 for the change of x1: x2 is shown. As can be seen in FIG. 10, when the inclination angle t of the light path converting member 20 is 55 °, the light emitted from the light source 1 with respect to the x1: x2 change is ± 3 ° at an angle (0 °) perpendicular to the display surface. It is emitted within the range. Therefore, the optimum condition of the inclination angle t of the trapezoidal optical path changing member in which the light irradiated from the light source 1 can be emitted perpendicularly to the display surface for all x1 and x2 is approximately 52 ° to 58 °.

FIG. 11 shows the light source 2-3 in FIG. 5A and fixes the size (width) and spacing of the electrode pattern to a = 12μm, b = 8μm, c = 12μm, d = 8μm, and shows x1 and x2. The emission light distribution when changed under the same condition as 10 is shown. As can be seen from FIG. 11, when the length of x1 varies from 3.0 μm to 1.5 μm, the light having the highest luminance value among the light emitted from the light source 2-3 is emitted vertically with respect to the display surface, whereas x1 When the length of X is 1.0 μm or less, the light having the highest luminance value is shifted in the + direction and emitted. When the emitted light is emitted while being shifted in the + direction, the highest luminance value appears at two angles of approximately + 24 ° and 42 ° to 44 °.

12 shows that the base e of the trapezoidal optical path converting member 20 is fixed to 8 μm when the length of x1 is 1.0 μm and 0.0 μm, and the inclination angle t and the height f are 65 °, 5.5 μm, and 70 °, respectively. The emission light distribution of the light irradiated from the light source 2-3 when changing to 4 micrometers is shown.

In conclusion, when summarizing the simulation data for determining the inclination angle t as described above, trapezoids are obtained for the arbitrary size of light source and the size (width), spacing, and overlapping width of the electrode patterns 11 and 12 of the MEMS panel 30. The inclination angle t of the light path converting member 20 should be determined at an angle between at least 52 ° and at most 70 °. In addition, the height f of the trapezoidal light path converting member 20 must be greater than the distance T between the upper movable electrode 11 and the lower fixed electrode 12 in order to obtain an optimal output light distribution and light efficiency, and the length e of the bottom side is When an electric field is applied to the movable electrodes 11 and the lower fixed electrode 12, the width b between the upper movable electrodes 11 must be smaller than the width b so as to realize a black state.

As described above, the transmissive display device using the fine optical modulator according to the present invention is an optical path converting member for bending a path of light incident through the lower fixed electrodes and the upper movable electrodes toward a display surface, wherein the optical path The angle of inclination, height, and length of the bottom surface formed by the incident surface and the bottom surface of the light path conversion member are optimally determined so that the light reflected by the conversion member is perpendicular to the display surface.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (7)

In the display device having a plurality of fixing members and a plurality of movable members for opening and closing the optical path, An optical path conversion member installed on the fixing member to convert a path of light incident inclinedly between the fixing members and the movable members in a direction perpendicular to the display surface; The angle of the incident surface formed on one side of the light path converting member is determined to be at least 52 ° or more relative to the display surface. The method of claim 1, The light path converting member is a transmissive display device using a fine light modulator, characterized in that the material is made of a high reflectivity. delete The method of claim 2, Transmissive display device using a fine optical modulator, characterized in that the cross section of the optical path conversion member is trapezoidal. The method of claim 1, The angle of the incident surface formed on one side of the optical path conversion member is a transmission type display device using a fine optical modulator, characterized in that determined by any angle between 52 ° to 70 ° relative to the display surface. The method of claim 1, The optical path converting member is a transmissive display device using a fine optical modulator, characterized in that formed in a height greater than the gap between the fixing member and the movable member. The method of claim 1, The bottom side of the optical path converting member is determined to be smaller than the distance between the movable members.

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