JP2003029295A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a utilization factor of a light source. SOLUTION: In a transmissive or a transflective liquid crystal display device, a shading area part (the part where there are gate wiring, source wiring, TFTs, pixel reflecting electrode, or the like) on the upper surface of a pixel electrode side glass substrate is provided with a reflective film 2 for reflecting the light made incident to the shading area from the light source as a pattern, and an insulating film 3 is formed thereon as a pattern, and the TFTs, wiring, or the like are constructed on this insulating film 3. The incident light made incident to the liquid crystal display device from the light source but not made incident to a transmitting area including pixel transparent electrodes 4a therein is reflected by the reflecting film 2 and returns to the light source side, and is reflected by the light source side reflecting plate and made incident to the liquid crystal display again. The utilization factor of the light therefore is improved and also the light source can be increased in an apparent quantity of the emitted light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive type or a transmissive type capable of improving the light source utilization efficiency of a liquid crystal display device,
The present invention relates to a reflective combined liquid crystal display device.

[0002]

2. Description of the Related Art An active drive type liquid crystal display device (L
CD) includes pixel electrodes provided in a matrix on a glass substrate, a plurality of gate lines for supplying scanning signals and a plurality of source lines for supplying display signals, which are arranged so as to pass through the periphery of the pixel electrodes and are orthogonal to each other. , TFT (thin film transistor) provided near the intersection of the gate line and the source line
It is composed of an equal switching element, a counter electrode provided on a counter substrate which is arranged to face the pixel electrode side with a liquid crystal interposed therebetween, a color filter and the like.

TF using the switching element as a TFT
In the structure of one pixel of the T drive system, as shown in FIG. 6, the pixel electrode 4 is surrounded by the gate wiring 6 and the source wiring 7, and the TFT 5 provided at the intersection of the gate wiring 6 and the source wiring 7.
Gate, source, and drain of the gate wiring 6,
The structure is such that it is connected to the source line 7 and the pixel electrode 4. In addition, as shown in FIG. 7, the cross-sectional structure of the TFT 5 is such that the gate electrode 5a is formed on the glass substrate 1 and the gate wiring 6 is formed.
An insulating film 5b that is formed together with the gate electrode 5a and the gate wiring 6 is applied, and the gate electrode 5 is formed through the insulating film 5b.
an insulating semiconductor layer 5c, semiconductor N ⁺ layers 5d, 5f on a,
The channel protection film 5e is sequentially formed, the source 5f is formed on the semiconductor N ⁺ layer 5d, the drain 5 is formed on the semiconductor N ⁺ layer 5f, and the protection film 5i is formed thereon.

The liquid crystal display device is shown in FIGS.
As shown in (C), there are a transmission type, a reflection type, and a semi-transmission type (combined with the transmission type and the reflection type). In the transmissive type, the pixel electrode formed on the glass substrate 1 is the transparent electrode 4a. In the reflective type, the pixel electrode 4 is a reflective electrode 4b whose upper surface is an irregular reflective surface. In the transflective type, the pixel electrode 4 is composed of a transparent electrode 4a and a reflective electrode 4b. Usually, a transparent electrode film is formed on the entire area as the pixel electrode 4, and the reflective electrode 4b is formed on the transparent electrode film. The portion of the transparent electrode film where the reflective electrode film does not overlap functions as the transparent electrode 4a. The transparent electrode 4a is provided inside the reflective electrode 4b as shown by the dotted line in FIG. A polarizing plate 9 is provided on the lower surface of the reflective and semi-transmissive glass substrate 1.

On the liquid crystal 10 side of a counter glass substrate 11 of a transmissive, reflective, or semi-transmissive liquid crystal display device, a counter electrode (transparent electrode) 12 and a color filter 1 for R, G, B, etc. are provided.
3 is provided, and a polarizing plate 16 is provided on the display side of the counter glass substrate 11. Although not shown,
The counter glass substrate 11 is provided with a black mask (light-shielding film) for protecting the TFT 5 and the like from outside light. In addition, the pixel electrode 4, the TFT 5 provided on the glass substrate 1,
The liquid crystal 10 such as the color filters 13 provided on the entire surface of the wirings 6, 7 and the like in contact with the liquid crystal 10 and the counter glass substrate 11.
An alignment film for aligning the molecules of the liquid crystal 10 in a predetermined direction is provided on the entire surface in contact with.

In the transmissive liquid crystal display device and the transflective liquid crystal display device, as shown in FIGS. 9 and 10, light from a light source (not shown) is incident on the glass substrate 1 and is transparent. Light incident on the transmissive display portion A where the electrode 4a is located is transmitted to the device display side in the transmissive mode. In the transmissive liquid crystal display device, the pixel electrode 4 is composed of the transparent electrode 4a, the transmissive display portion A is wide, and the image quality is the best in a normal environment, but there is no reflection plate (reflection electrode) that reflects external light. Therefore, visibility in the sun is poor. In the reflective liquid crystal display device, the entire pixel electrode is the reflective electrode 4b, and external light is used as the reflective electrode 4b.
Since it is reflected by b, the visibility of the display under external light is good, but since no light source is used, the display cannot be seen in the dark part. The transflective liquid crystal display device has a transmissive display portion A and a reflective display portion C, and although it looks like a bright / dark portion, both are inferior to the transmissive / reflective type.

Further, in a semi-transmissive liquid crystal display device, unevenness is applied to a reflective electrode, and ambient light at various incident angles is effectively used as display light. The reflective electrode is provided below a transparent electrode through a transparent insulating film. Provided so that the optical path lengths in the liquid crystal layer in the reflective area and the transmissive area of the pixel electrode are made close to each other so that the characteristic changes of the light in the liquid crystal layer in the reflective area and the transmissive area of the pixel electrode are made uniform. (Patent No. 2955277).

[0008]

SUMMARY OF THE INVENTION Transmission type and transmission type,
The liquid crystal display device used in combination with the reflection type displays the transmission mode,
Regarding the pattern on the light source side, sufficient consideration is given to masking the portion affected by incident light with a light-shielding film and eliminating light leakage outside the display region. Therefore, the structure is such that light is not transmitted except in the transmissive display region.

A liquid crystal display device in which the display portion is sufficiently larger than the wiring portion, that is, the transmissivity is sufficiently large has a small optical loss in the wiring portion, but the wiring width itself is high in the transmissive liquid crystal display device having a large number of pixels. Since it does not change, the proportion occupied by the wiring portion relatively increases and the transmittance decreases.

Further, in the transmissive / reflective liquid crystal display device, since the pixel portion used in the reflective mode in the display portion is closed when viewed from the transmissive direction, the light utilization efficiency in the transmissive mode is That is, the transmittance is lowered.

In these portions where the transmitted light does not pass, the incoming and outgoing light is scattered and absorbed and does not contribute to the image display. Therefore, in order to realize an image with sufficient brightness, it is necessary to increase the brightness of the light source itself or increase the transmittance.

When increasing the brightness of the light source, the power consumption increases, and it is necessary to reduce the power consumption as much as possible.
The liquid crystal device used in combination with the transmissive type or the reflective type increases the power load on the camcorder, the digital camera, the morphological information device and the like.

The present invention has been made to solve the above problems, and it is possible to improve the utilization efficiency of a light source by reflecting the incident light from the light source and returning it to the light source with respect to portions other than the transmissive display pixels. It is an object of the present invention to provide a transmissive type or a transmissive type / reflective type liquid crystal display device.

[0014]

According to the present invention, a plurality of gate wirings, a plurality of source wirings provided so as to intersect with the gate wirings, and a switching provided near an intersection of the gate wirings and the source wirings are provided. A transparent substrate having an element and a pixel transparent electrode connected to the switching element,
A transmissive liquid crystal display device in which incident light from a light source is transmitted to a display side through a transparent region in a transmissive mode, or a plurality of gate wirings, a plurality of source wirings provided so as to intersect with the gate wirings, and the gates. A light source in a transmission mode having a switching element provided near an intersection of a wiring and a source wiring, and a pixel transparent electrode connected to the switching element and a pixel reflection electrode for reflecting external light In the transmissive and reflective liquid crystal display device, in which incident light from is transmitted to the display side through a transparent region, a reflective film for reflecting incident light from the light source as a pattern is provided in a light shielding region portion on the upper surface of the transparent substrate, The switching element is constructed on the reflective film via an insulating film.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 FIG. 1 shows a cross-sectional structure of a transmissive / reflective liquid crystal display device according to Embodiment 1 of the present invention. In this liquid crystal display device, the upper surface of the portion of the glass substrate 1 on the pixel electrode side which becomes the light shielding region, that is, the gate wiring 6, the source wiring 7, the FET
5, a reflection film 2 for reflecting the incident light from the light source to the light source side is formed as a pattern on the upper surface of the portion where the reflection electrode 4b and the like are provided, and further, the insulating film 3 is formed as a pattern on the reflection film 2. Then, on the glass substrate 1 on which the reflective film 2 and the insulating film 3 are formed, the gate wiring 6, the source wiring 7, and the T wiring 7 are formed in the same manner as in the conventional transmissive / reflective liquid crystal display device.
The configuration is such that the FT 5, the transparent electrode 4a, the reflective electrode 4b, and the like are formed. Further, similarly to the conventional case, the light distribution film 8 is provided on the surface of the gate wiring 6, the source wiring 7, the TFT 5, the transparent electrode 4a, the reflective electrode 4b, etc., which is in contact with the liquid crystal 10, and the polarizing plate 9 is formed on the lower surface of the glass substrate 1. Is provided. Further, on the counter glass substrate 11, a transparent electrode (counter electrode) 12, a black mask 14 for blocking external light to the gate wiring 6, the source wiring 7, the TFT 5, etc., and an alignment film 15 for aligning liquid crystal 10 molecules. A polarizing plate 16 and the like are provided.

Wirings, TFTs on the glass substrate 1,
A procedure for forming the pixel electrode and the like will be described. First, a reflective film is formed on the upper surface of the glass substrate 1 by a sputtering method using a material similar to that of the conventional reflective electrode 4b, for example, aluminum or silver so that the surface in contact with the glass substrate 1 is a mirror surface, and has a predetermined shape. To form a pattern of the reflection film 2 in the portion which will be the light-shielding region, a photosensitive insulating film is applied thereon, and development processing is performed according to a predetermined pattern.
The insulating film 3 is formed as a pattern on the reflective film 2. Then, the gate wiring 6, the source wiring 7, the TFT 5, the pixel reflection electrode 4b and the like are formed on the insulating film 3 of the glass substrate, and the pixel transparent electrode 4a is formed in the portion where the insulating film 3 is not present.

That is, the gate 5a of the TFT 5 is formed on the insulating film 3 of the glass substrate 1 on which the reflective film 2 and the insulating film 3 are provided.
Then, a gate wiring is formed, an insulating film 5b is formed on the gate 5a and the gate wiring, a transparent electrode film 4a 'is formed on the entire portion to be a pixel electrode region, and a reflective electrode 4b is formed thereon. Next, the semiconductor layer 5c of the TFT 5, the channel protection film 5d, and the semiconductor N ⁺ layers 5e and 5f are sequentially formed, and TF
The source 5g of T5, the source wiring 7 and the drain 5h of the TFT 5 are formed so as to be connected to the transparent electrode film 4a 'and the reflective electrode 4b. Then, the protective film 5i is applied to the source wiring 7 and the drain 5h of the TFT 5. The portion of the transparent electrode film 4a 'where the reflective electrode 4b does not overlap becomes the transparent electrode 4a and becomes the transmissive region.

As shown in FIG. 2, the above-mentioned transmissive / reflective liquid crystal display device has a light-shielding area B on the upper surface of the glass substrate 1 on which the gate wiring 6, the source wiring 7, the TFT 5, the reflective electrode 4b and the like are provided.
Since the reflection plate 2 for reflecting the incident light from the light source is provided in the portion, the conventional light shielding area B becomes the reflection area B of the light source light,
The incident light that has entered the reflection area B from the light source is reflected by the reflection film 2 and returns to the light source side, is reflected by the reflection plate on the light source side, and enters the liquid crystal display device again.

FIG. 3 shows a light source device 20 of the above-mentioned transmissive / reflective liquid crystal display device combined with a light source 21 and an inclined reflector 22.
This is an example of an edge light type backlight composed of. In this case, the light source 21 is composed of a fluorescent tube, an LED, etc., and the light from the light source 21 is reflected by the reflecting plate 22 and enters the liquid crystal display device (LCD). The light entering and blocking the transparent area A of the liquid crystal display device becomes the transmitted light. On the other hand, the light entering and blocking from the light source to the reflection area B is reflected by the reflective film 2, returns to the light source side, is reflected by the light source side reflection plate 222, and becomes incident light to the liquid crystal display device again.

This transmissive and reflective liquid crystal display device is
As described above, since the incident light from the light source that does not enter the transmissive area A is reflected by the reflective film 2 and returns to the light source side to be reflected and condensed, the utilization efficiency of the backlight light is improved. At the same time, it is possible to increase the apparent light emission amount of the light source.

Embodiment 2 FIG. 4 shows a sectional structure on the pixel side in a transmissive liquid crystal display device according to Embodiment 2 of the present invention. In this liquid crystal display device, the pixel electrode 4 is composed of only the transparent electrode 4a.
Other configurations are similar to those of the transmissive and reflective liquid crystal display device of FIG. 1 described above, and therefore, the same components as those shown in FIG. Is omitted. That is, this transmissive liquid crystal display device,
A reflection film 2 for reflecting the incident light from the light source to the light source side and an insulating film 3 for covering the reflection film 2 are formed in a pattern on the light shielding region B on the upper surface of the glass substrate 1.
A gate wiring 6, a source wiring 7, a TFT 5 and the like, and a transparent electrode (pixel electrode) 4a and the like are formed on the glass substrate 1 on which the insulating film 3 is formed, as in the conventional transmissive liquid crystal display device. is there. The cross-sectional structure of the counter electrode side is similar to that of a conventional transmissive liquid crystal display device, and includes a counter glass substrate 11, a transparent electrode (counter electrode) 12, a color filter 13, a black mask 14, an alignment film 15, a polarizing plate 16 and the like. It is configured.

The transmissive liquid crystal display device is as shown in FIG.
Gate wiring 6, source wiring 7, T on the upper surface of the glass substrate 1
Since the reflection plate 2 for reflecting the incident light from the light source is provided in the part of the light shielding area B such as FT5, the conventional light shielding area B is
The incident light which becomes the reflection area B of the light source light and enters the reflection area B from the light source is reflected by the reflection film 2 and returns to the light source side,
The light is reflected by the light source side reflection plate and again enters the liquid crystal display device.

When the light source device of the transmissive liquid crystal display device is a backlight using an edge light system composed of a light source 21 and an inclined reflecting plate 22 as shown in FIG. 3, the light from the light source 21 is reflected. The light is reflected by the plate 22 and enters the liquid crystal display device. Light entering / exiting the transmissive area A of the liquid crystal display device becomes transmitted light, and light entering / exiting the reflective area B is reflected by the reflective film 2 and returned to the light source side to be reflected by the reflection plate 22 on the light source side, and again to the liquid crystal display device. It becomes incident light.

Therefore, according to this transmissive liquid crystal display device, like the transmissive and reflective liquid crystal display device,
It is possible to improve the utilization efficiency of the backlight light and increase the apparent light emission amount of the light source.

In the above, the case of the edge light system as the backlight has been described, but the same effect as described above can be obtained by using a backlight of another system.

[0026]

As described above, the present invention has the following effects because the reflection film for reflecting the incident light from the light source is provided in the light-shielding area portion on the upper surface of the transparent substrate (glass substrate).

(1) The power consumption of the backlight, which is a display light source, can be reduced without lowering the display brightness. Therefore, when the power source of the light source is a battery, the battery lasts a long time. (2) The display image can be brightened without increasing the power consumption of the backlight. (3) Since only the structure of the liquid crystal display device is changed, it is not necessary to change the structure of the light source. (4) There is almost no change in the external dimensions of the display device because it can be handled only by adding a pattern. (5) Since the conventional manufacturing process can be used for the manufacturing, the reflecting plate can be manufactured with extremely high accuracy as compared with the method of attaching a similar reflecting layer to the outside.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a transmissive / reflective liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a transmissive display portion and a reflective area of the liquid crystal display device.

FIG. 3 is an explanatory diagram of reflected light of the liquid crystal display device.

FIG. 4 is a sectional configuration diagram of a transmissive liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is an explanatory view of a transmissive display portion and a reflective area of the liquid crystal display device.

FIG. 6 is a structural explanatory view of one pixel of the liquid crystal display device.

FIG. 7 is an explanatory diagram of a cross-sectional structure of a thin film transistor.

FIG. 8 is an explanatory cross-sectional configuration diagram of a conventional transmissive, reflective, or semi-transmissive liquid crystal display device.

FIG. 9 is an explanatory diagram of a transmissive display portion and a light-shielding area of a conventional transmissive liquid crystal display device.

FIG. 10 is an explanatory diagram of a transmissive display portion and a light-shielding area of a conventional transmissive / reflective liquid crystal display device.

[Explanation of symbols]

1 ... Glass substrate on the pixel side (transparent substrate) 2 ... Reflective film (reflector) 3 ... Insulating film 4 ... Pixel electrode 4a ... Pixel transparent electrode 4b ... Pixel reflective electrode 5 ... TFT (thin film transistor) 6 ... Gate wiring 7 ... Source wiring 8 ... Light distribution film 9 ... Polarizing plate 10 ... Liquid crystal (liquid crystal layer) 11 ... Opposing glass substrate 12 ... Opposite transparent electrode 13 ... Color filter 14 ... Black mask (light-shielding film) 15 ... Light distribution film 16 ... Polarizing plate 20 ... Light source device 21 ... Light source 22 ... Reflector

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09F 9/35 G09F 9/35 F term (reference) 2H091 FA14Y FA34Y FA41Z GA02 GA03 GA07 GA13 LA11 LA17 LA18 2H092 JA26 JB07 JB22 JB31 NA01 NA07 PA09 PA12 PA13 5C094 AA10 AA22 BA03 BA43 CA19 CA24 DA14 DA15 DB04 EA04 EA06 EA07 EB02 ED03 ED11 ED15

Claims (3)

[Claims] 1. A plurality of gate wirings, a plurality of source wirings provided so as to intersect with the gate wirings, a switching element provided near an intersection of the gate wirings and the source wirings, and a connection to the switching element. In a transmissive liquid crystal display device that has a transparent substrate with a pixel transparent electrode that is formed, the incident light from the light source in the transmissive mode is transmitted to the display side through the transparent region, in the light-shielding region portion of the transparent substrate upper surface, A liquid crystal display device, characterized in that a reflective film for reflecting incident light from the light source is provided as a pattern, and the switching element is constructed on the reflective film via an insulating film. 2. A plurality of gate wirings, a plurality of source wirings provided so as to intersect with the gate wirings, a switching element provided near an intersection of the gate wirings and the source wirings, and a connection to the switching element. Transparent and reflective liquid crystal display having a transparent substrate having a transparent pixel electrode and a pixel reflective electrode for reflecting external light, and transmitting incident light from a light source to a display side through a transparent region in a transmissive mode. In the device, a reflective film for reflecting incident light from the light source is provided as a pattern in a light-shielding region portion on the upper surface of the transparent substrate, and the switching element is constructed on the reflective film via an insulating film. Liquid crystal display device. 3. The liquid crystal display device according to claim 1, wherein the switching element is a thin film transistor.