JPH05241514A - Display device - Google Patents

Abstract

PURPOSE:To provide a bright, thin and light-weight display device with high accuracy. CONSTITUTION:A matrix substrate is provided with an insulation board 11, a scanning line, a signal wiring, a pixel electrode 14 formed on the insulation board 11 in a matrix shape, a TFT provided on the crossing part of the scanning line and the signal wiring and operating as a switching element connecting or interrupting electrically the signal wiring and the pixel electrode 14, an optical waveguide 16 provided downward the pixel electrode 14 and the optical waveguide 21 intersecting orthogonally with the optical waveguide 16. The optical waveguides 16 are formed with three continuous pieces as a set and the optical waveguides 16 of each set are colored in order of red, green and blue. A beam outgoing from a light source 22 provided on each end part of the optical waveguide 21 respectively passes through the optical waveguide 21 and after the optical path of the beam is converted in an optical path conversion part 23, the beam is guided into the optical waveguide 16 and emits in the direction of observation upward the surface of a figure at the pixel electrode 14. The beams outgoing from the pixel electrodes 14 become red, green and blue since respective optical waveguides 16 are colored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for displaying an image by applying a drive signal to pixel electrodes arranged in a matrix through a switching element.

[0002]

2. Description of the Related Art For example, a conventional liquid crystal display device is constructed so that an image is displayed on a screen by selectively driving picture element electrodes arranged in a matrix. is there.

As one of the methods for selectively driving the picture element electrodes in this way, there is known an active matrix driving method in which a switching element is connected to each of the independent picture element electrodes to selectively drive the picture element electrodes. Has been.

As a switching element for selectively driving this pixel electrode, a TFT (thin film transistor) element, an MIM (metal-insulating film-metal) element, and an M element are generally used.
An OS (metal oxide semiconductor) transistor element or the like is used.

With this switching element, a pixel electrode and
By turning on / off the voltage applied between the counter electrode and the opposite electrode, the display medium composed of the liquid crystal layer interposed between both electrodes is optically modulated, and an image is formed by this optical modulation. To be done.

Since such an active matrix driving system is capable of high-contrast display, it has been put to practical use in liquid crystal televisions, word processors, terminal display devices of computers, and the like.

By the way, such a display device, for example, T
The liquid crystal display device using the FT has two types of reflection type and transmission type.
There are different types.

Since the display of the reflection type display device is difficult to see in a place which is not bright, the transmission type display device is mainly used for liquid crystal televisions, laptop type word processors, computers and the like. In recent years, word processors and computers have become thinner and lighter from laptops to notebooks, and accordingly, demands for thinner and lighter display devices are increasing.

FIG. 4 is a perspective view showing the structure of a matrix substrate of a conventional active matrix liquid crystal display device.

As shown in the figure, this matrix substrate comprises a glass substrate 51, scanning lines 52, signal lines 53, picture element electrodes 54 made of a transparent conductive film, and TFTs 55.

The scanning lines 52, the signal lines 53 and the picture element electrodes 54 are arranged in a matrix on the glass substrate 51. A TFT 55 is connected to each of the picture element electrodes 54 as a switching element.

The TFT 55 is turned on / off by a signal from the scanning line 52, and when it is in the on state, the pixel electrode 54 is connected to the signal line 53.

FIG. 5 is a sectional view showing a structural example of a conventional transmissive liquid crystal display device using the matrix substrate of FIG.

As shown in the figure, a transparent insulating substrate 61
A picture element electrode 62 is disposed on the above.

A substrate 63 is arranged so as to face the substrate 61, and a counter electrode 64 is formed on the substrate 63. A red (R), green (G), and blue (B) color filter 66 for performing color display on a notebook computer or a wall-mounted television is provided on the counter electrode 64 at a position corresponding to the pixel electrode 62. It is provided.

A liquid crystal layer 65 is interposed between the substrate 61 and the substrate 63, and a backlight 67 composed of a fluorescent tube or the like is provided behind the substrate 61 in order to make the liquid crystal display screen bright and easy to see. There is.

A reflection plate 68 is provided so as to surround the backlight 67 with respect to the substrate 61, and the reflection plate 68 is configured to reflect the light from the backlight 67 to the pixel electrode 62 side.

Therefore, in the conventional liquid crystal display device, light from the backlight 67 is applied from below the matrix substrate, and color liquid crystal display is performed by the color filter 66 on the counter electrode 64.

[0019]

Since such a conventional display device uses a backlight, it is difficult to reduce the thickness and weight of a liquid crystal display device such as a laptop or notebook computer. There is. Specifically, (1) it is difficult to make the display device thinner than a few ten millimeters, and it is difficult to reduce the weight because a backlight, a reflector, etc. are required.

(2) The brightness of the display screen varies depending on the shape of the backlight.

(3) The noise generated from the backlight causes deterioration of display quality and adversely affects peripheral equipment.

(4) Care must be taken in handling the device due to the temperature rise due to the backlight.

Further, since the color filter is used, there are the following problems. That is, (5) the manufacturing process of the color filter is complicated and the color filter is expensive, resulting in high cost.

(6) When the matrix substrate and the substrate on the color filter side are bonded together, the color filter and the pixel electrode are likely to be displaced, and the aperture ratio is lowered.

(7) The color filter becomes an obstacle to further thinning of the device.

Therefore, the present invention solves such problems and provides a high-definition, bright, thin and lightweight display device without using a backlight or a color filter.

[0027]

A display medium, a plurality of picture element electrodes for driving the display medium, a plurality of signal lines arranged in a row or column direction, and a plurality of signal lines crossing each other. A plurality of scanning lines arranged in a plurality of lines, a plurality of optical waveguides provided below the plurality of pixel electrodes and colored red, green, and blue, respectively, and a plurality of scanning lines based on signals from the scanning lines. And a switching element for electrically connecting each of the picture element electrodes and a signal line corresponding to the picture element electrode.

[0028]

The switching element electrically connects each of the plurality of picture element electrodes to the signal line corresponding to the picture element electrode based on the signal from the scanning line. As a result, a voltage is applied to the picture element electrode, the display medium corresponding to the picture element electrode is optically modulated, and an image is displayed. Below the picture element electrodes, optical waveguides colored red, green and blue are provided respectively. Since the picture element electrodes are illuminated from below by the light from the optical waveguides, there is no need for backlighting as in the conventional case. Since it is not necessary to use, and since the optical waveguide is colored, it is not necessary to use a color filter, and therefore a bright, thin, lightweight display device with high definition can be realized.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. Here, a liquid crystal display device will be described as an example of the display device according to the present invention.

FIG. 1 is a plan view showing an arrangement of optical waveguides formed on a matrix substrate of an embodiment of a display device according to the present invention. FIG. 2 is a perspective view showing the structure of a matrix substrate of an embodiment of the display device according to the present invention.

As shown in FIG. 2, this matrix substrate includes a transparent insulating substrate 11, scanning lines 12, signal wirings 13 made of metal wiring, picture element electrodes 14, TFTs 15 and optical waveguides 16.

The picture element electrodes 14 are formed in a matrix on the insulating substrate 11.

A scanning line 12 is formed on the insulating substrate 11 for each row (or each column) of the picture element electrodes 14, and a signal made of a metal material is provided for each column (or each row) of the picture element electrodes 14. The wiring 13 is provided so as to intersect the scanning line 12, for example, to be orthogonal.

A TFT 15 that operates as a switching element that electrically connects or disconnects the signal line 13 and the pixel electrode 14 is provided at the intersection of the scanning line 12 and the signal line 13.

The signal wiring 13 and the pixel electrode 14 are provided on both sides of the TFT 15.
The TFT 15 is turned on / off by a signal from the scanning line 12, and the pixel electrode 14 is connected to the signal wiring 13 when in the on state.

An optical waveguide 16 is provided below the picture element electrode 14.

As shown in FIG. 1, the optical waveguides 16 are made up of three continuous optical waveguides, and the optical waveguides 16 of each group are colored in the order of red (R), green (G) and blue (B). There is.

The insulating substrate 11 has a structure 3 which is orthogonal to the optical waveguide 16.
A book optical waveguide 21 is provided, and at each end of the optical waveguide 21, a light source 22 that emits white light, such as an LED (light emitting diode) or an LD (laser diode), is provided.

The light emitted from the light source 22 travels in the optical waveguide 21, and is subjected to optical path conversion in the optical path conversion unit 23, and then the optical waveguide.
It is guided to the inside of 16 and is emitted by the pixel electrode 14 in the observation direction above the drawing sheet. However, FIG. 1 shows only some of the pixel electrodes.

Since each of the optical waveguides 16 is colored as described above, the light emitted from the pixel electrode 14 is red, green and blue light. Therefore, the picture element is colored, and bright color display is possible.

FIG. 3 is a sectional view showing the structure of a liquid crystal display device using the matrix substrate of FIGS.

As shown in the figure, the picture element electrodes 14 are arranged in a matrix on the transparent insulating substrate 11, and the optical waveguide 16 is provided below the picture element electrodes 14. Has been.

A substrate 25 is arranged so as to face the insulating substrate 11, and a counter electrode 26 is formed on the pixel electrode 14 side of the substrate 25. A liquid crystal layer 27 is interposed between the insulating substrate 11 and the substrate 25.

Scan line 12 is one embodiment of the multiple scan lines of the present invention. The signal wiring 13 is an example of the plurality of signal lines of the present invention. The picture element electrode 14 is an embodiment of the plurality of picture element electrodes of the present invention. The TFT 15 is an example of the switching element of the present invention. The optical waveguide 16 is an embodiment of the plurality of optical waveguides of the present invention. The liquid crystal layer 27 is an example of the display medium of the present invention.

Next, a method of manufacturing the matrix substrate will be described.

On the surface of the insulating substrate 11 made of, for example, a glass substrate, the width is 100 μm and the depth is 5 μm by the K ⁺ ion exchange method.
The optical waveguide 16 of is formed. In this step, the K ⁺ ion exchange method is carried out three times, and predetermined positions of the optical waveguide 16 are colored red, green and blue, respectively.

After that, the optical waveguide 21 is formed on the surface of the insulating substrate 11 by a normal semiconductor process. Next, one end of the optical waveguide 21 is connected to the light source 22 composed of, for example, an LED.

Further, an optical path changing portion 23 is provided by forming an optical waveguide in the shape of a lens at the connecting portion between the optical waveguide 16 and the optical waveguide 21, and the optical path can be bent in the optical path changing portion 23.

Next, a transparent electrode made of an ITO (tin-doped indium oxide) film having a thickness of 1000 Å is formed as a pixel electrode 14 on the optical waveguide 16.

A TFT 15 made of amorphous Si (silicon), which is a switching element, is connected to the pixel electrode 14 and T
The signal wiring 13 is connected to the source electrode of the FT 15. Also, TF
The gate electrode of T15 is connected to the scanning line 12.

The matrix substrate manufactured in this manner is bonded to the substrate 25 on the opposite side on which the counter electrode 26 is formed, and liquid crystal is sealed between both substrates to form the liquid crystal layer 27. Is manufactured.

In this liquid crystal display device, when light from the light source 22 is made incident on the optical waveguide 21 to display an image,
A bright color display without display unevenness was obtained.

Therefore, according to this embodiment, a high-definition, bright, thin, and lightweight display device can be realized without using a backlight and a color filter which are conventionally provided.

That is, in this embodiment, an optical waveguide is provided below the picture element electrode, and three continuous optical waveguides constitute one set, and the optical waveguides of each set are colored red, green and blue, respectively. Therefore, for example, when light is incident from the end of the optical waveguide, each of the pixel electrodes is illuminated from below by the light from the optical waveguide, so it is necessary to use a backlight such as a fluorescent tube as in the conventional case. Disappear. As a result, (1) the device can be made thin and lightweight.

(2) The uneven brightness of the display screen can be eliminated.

(3) Since the noise due to the backlight is eliminated, the display quality is improved, and the adverse effect of the noise on the peripheral equipment is eliminated.

(4) The temperature rise due to the backlight is eliminated, and the device is easy to handle.

Further, since the optical waveguides are colored red, green and blue with one set of three, color filters are unnecessary. As a result, (5) the cost of the device can be reduced.

(6) The problem of lowering the aperture ratio can be solved.

(7) The device can be made thinner.

When the liquid crystal material requires a polarizing plate, a polarizing system may be provided on the light emitting side of the light source 22, that is, the optical waveguide 21 side. In this case also, one external polarizing plate is used. It is efficient because it can be done.

[0062]

As described above, the present invention provides a display medium, a plurality of picture element electrodes for driving the display medium, a plurality of signal lines arranged in the row or column direction, and a plurality of signal lines. From the scanning lines, a plurality of scanning lines that are arranged so as to intersect with the signal lines of, and a plurality of optical waveguides that are provided below the plurality of pixel electrodes and colored red, green, and blue, respectively, A switching element that electrically connects each of the plurality of picture element electrodes to a signal line corresponding to the picture element electrode based on the signal. Therefore, a high-definition, bright, thin, and lightweight display device can be realized without using the backlight and color filter provided in the conventional display device.

[Brief description of drawings]

FIG. 1 is a plan view showing an arrangement of optical waveguides formed on a matrix substrate of an embodiment of a display device according to the present invention.

FIG. 2 is a perspective view showing a configuration of a matrix substrate of an embodiment of a display device according to the present invention.

FIG. 3 is a sectional view showing a configuration of a liquid crystal display device using the matrix substrate of FIGS. 1 and 2.

FIG. 4 is a perspective view showing a configuration of a matrix substrate of a conventional active matrix liquid crystal display device.

5 is a cross-sectional view showing a configuration example of a conventional transmissive liquid crystal display device using the matrix substrate of FIG.

[Explanation of symbols]

 11 Insulating substrate 12 Scanning line 13 Signal wiring 14 Picture element electrode 15 TFT 16, 21 Optical waveguide 22 Light source 23 Optical path conversion unit 25 Substrate 26 Counter electrode 27 Liquid crystal layer

Claims (2)

[Claims] 1. A display medium, a plurality of picture element electrodes for driving the display medium, a plurality of signal lines arranged in a row or column direction, and an arrangement intersecting the plurality of signal lines. A plurality of scanning lines provided, a plurality of optical waveguides provided below the plurality of pixel electrodes and colored red, green, and blue, respectively, and based on signals from the scanning lines, A display device comprising: each of a plurality of picture element electrodes and a switching element electrically connecting the signal line corresponding to the picture element electrode. 2. The display device according to claim 1, further comprising a light emitting element that allows light to enter the plurality of optical waveguides.