KR100796759B1 - Semitransparent type liquid crystal display - Google Patents

Abstract

The present invention relates to a transflective liquid crystal display device that displays an image by using external natural light or backlight light. The transflective liquid crystal display device according to the present invention is opposed to a first insulating substrate and a first insulating substrate, and is a reflection mode. A second insulating substrate having two regions divided into a region and a transmission mode region, a liquid crystal layer injected and sealed between the first and second insulating substrates, and upper and lower polarizers attached to the front and rear surfaces of the liquid crystal layer, respectively. 2 includes a reflecting projection formed on the lower surface of the insulating substrate and a condensing portion formed on the lower surface of the second insulating substrate and formed in a region other than the portion where the reflecting projection is formed, wherein the condensing lens is a convex lens. It features.

As a result, the overall light utilization efficiency of the transflective liquid crystal display device is improved by using the reflection protrusions and the convex lenses formed on the lower surface of the lower substrate.

Transflective Liquid Crystal Display, Backlight Unit (BLU), Convex Lens, Reflective Projection, Light Control.

Description

Transflective Liquid Crystal Display {SEMITRANSPARENT TYPE LIQUID CRYSTAL DISPLAY}

1 is a cross-sectional view illustrating a structure of a transflective liquid crystal display according to an exemplary embodiment of the present invention.

2 is a cross-sectional view illustrating a structure of a lower substrate for a transflective liquid crystal display according to an exemplary embodiment of the present invention.

3A to 3D are cross-sectional views illustrating a manufacturing process of a lower substrate according to an embodiment of the present invention.

※ Explanation of code about main part of drawing ※

10: upper polarizer

20: upper compensation film

30: upper substrate

40: reference electrode

51: TFT

52: transparent electrode

60: lower substrate

61: reflective projection

62: condenser                 

70: lower polarizer

80: lower compensation film

90: BLU (Back Light Unit)

The present invention relates to a transflective liquid crystal display device.

A liquid crystal display device is a display device that displays an image through light transmission and blocking using a liquid crystal material having dielectric anisotropy. The liquid crystal display device is a transmissive type that transmits backlight light to display an image and reflects natural light incident from the outside to display an image. It is divided into reflection type which makes it.

The transmissive liquid crystal display device has a high brightness of the screen because a back light unit is installed on the back to be used as its own light source, but it is difficult to apply to a portable device because of high power consumption.

On the other hand, the reflective liquid crystal display displays an image because the natural light incident from the outside is selectively transmitted by the switching action of the liquid crystal layer and is reflected back from the reflecting plate to be emitted to the front surface. The disadvantage is that it is difficult to use in bad and dark places.

The semi-transmissive liquid crystal display device to solve the shortcomings of the transmissive and reflective liquid crystal display device is to display an image using both the external incident light or the backlight unit light. It includes the upper and lower substrates, the transparent electrode, the insulating layer and the alignment layer are sequentially formed on the lower surface of the upper substrate and the upper surface of the lower substrate, and the upper and lower substrates are sealed and assembled with a sealing material therebetween. A liquid crystal material is injected into the space to form a liquid crystal layer.

In addition, a polarizing plate is attached to an outer surface (upper surface) of the upper substrate, and a semi-transmissive reflecting plate is attached to an outer surface (lower surface) of the lower substrate to reflect natural light incident through the upper substrate and to transmit backlight (BL) light. Doing.

However, the transflective liquid crystal display device having such a structure propagates the light from the backlight unit to all other areas other than the transmission area, thereby causing light loss. In particular, light entering the reflecting region is reflected without affecting the transmittance at all, thereby further increasing the light loss.

Therefore, there is a need for a method of realizing a clear screen by efficiently using the light reflected from the reflection area.

An object of the present invention is to provide a transflective liquid crystal display device which can implement a clear screen by improving light utilization efficiency.

In order to solve the technical problem, the present invention forms a convex lens and a reflective protrusion for adjusting the amount of light on the lower surface of the lower substrate.

Specifically, the transflective liquid crystal display device according to the present invention includes a first insulating substrate; A second insulating substrate facing the first insulating substrate and having two regions divided into a reflection mode region and a transmission mode region; A liquid crystal layer that is injection-sealed between the first insulating substrate and the second insulating substrate; Upper and lower polarizers attached to the front and rear surfaces of the liquid crystal layer, respectively; A reflection protrusion formed on a bottom surface of the second insulating substrate; And a light collecting portion formed on a lower surface of the second insulating substrate and formed in a region other than the portion where the reflective protrusion is formed.

In addition, a transistor substrate for a transflective liquid crystal display device according to the present invention includes an insulating substrate and a first signal line formed on the insulating substrate; A first insulating film formed over the first signal line; A second signal line formed on the first insulating film and crossing the first signal line; A thin film transistor connected to the first signal line and the second signal line; A second insulating film formed over the thin film transistor and having a first contact hole for exposing a predetermined electrode of the thin film transistor; A transparent electrode formed on the second insulating film and connected to the predetermined electrode of the thin film transistor through the first contact hole; A reflective electrode formed on the transparent electrode and having a transmission window; A reflection protrusion formed on a lower surface of the insulating substrate and overlapping the thin film transistor; It includes a convex lens formed on the lower surface of the insulating substrate and overlapping a portion of the transmission window and the transparent electrode.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view illustrating a structure of a transflective liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a reference electrode 40 is formed on an inner surface of an upper substrate 30 disposed opposite to a lower substrate 60, and a gate electrode is disposed between the reference electrode 40 and the lower substrate 60. And a thin film transistor (TFT) 51 and a transparent electrode 52 made of a source electrode, a drain electrode, a gate insulating film, an ohmic contact layer, an amorphous silicon layer, and the like.

An upper compensation film 20 made of λ / 2 or λ / 4 reflective film or the like is attached to an outer surface (upper surface) of the upper substrate 30, and an upper polarizing plate 10 is attached to the upper compensation film 20. have.

The lower surface of the lower substrate 60 is formed with a reflection protrusion 61 overlapping the thin film transistor 51 in the liquid crystal cell 100 to prevent light from entering the reflection area, and a lower portion connected to the reflection protrusion 61. The light collecting part 62 collects light entering the transmission region in the liquid crystal cell 100 and collects part of the light reflected from the semi-annular protrusion 61 to the transmission region of the upper substrate 30 on the lower surface of the substrate 60. ) Is formed.

Here, the light collecting part 62 is a convex lens formed by partially etching the lower substrate 60 according to an embodiment of the present invention. Hereinafter, the light collecting part 62 will be referred to as a convex lens.

A lower polarizer 70 is attached to an outer surface of the lower substrate 60 including the reflective protrusion 61 and the convex lens 62, and a λ / 2 or λ / 4 reflective film is attached to the lower surface of the lower polarizer 70. The lower compensation film 80 which consists of etc. is affixed. The lower surface of the lower compensation film 80 is attached to a BLU (Back Light Unit: Backlight Unit, 90), which includes a reflector (not shown).

The lower substrate for the transflective liquid crystal display device having the above structure will be described in more detail as follows.

2 is a cross-sectional view illustrating a structure of a lower substrate according to an embodiment of the present invention. Referring to FIG. 2, the lower substrate for a transflective liquid crystal display device includes a reflection mode region in which natural light incident from the outside is selectively transmitted by a switching action of the liquid crystal layer according to whether an electric field is applied from the outside to form an image display. A) and the backlight unit 90 provided on the rear surface of the liquid crystal display device include two regions divided into a transmission mode region B for transmitting an image and performing image display.

First, the upper structure of the lower substrate for the liquid crystal display device divided into the reflection mode region A and the transmission mode region B will be described in detail.

A gate line (not shown) for transmitting a scan signal and a gate electrode 100, which is a branch thereof, are formed on the first insulating substrate 60 made of a transparent material such as glass, and a gate is disposed on the gate line 101 and the gate electrode. An insulating film 102 is formed.

An amorphous silicon layer 103 is formed on the gate insulating film 102 on the gate electrode 100, and ohmic contact layers 104 and 105 made of n + amorphous silicon are formed thereon. The source electrode 106 and the drain electrode 107 are formed on the ohmic contact layers 104 and 105, respectively.

Here, the gate electrode 100, the source electrode 106, the drain electrode 107, the gate insulating layer 102, the ohmic contact layers 104 and 105, and the amorphous silicon layer 103 may form a thin film transistor TFT, 51. In this case, the amorphous silicon layer 103 between the source electrode 106 and the drain electrode 107 becomes a channel portion of the thin film transistor. That is, when the scan signal is applied to the gate electrode 100 through the gate line, the thin film transistor is turned on, so that the image signal applied to the source electrode 106 through the data line (not shown) is The amorphous silicon layer 103 is passed to the drain electrode 107.

A passivation layer 108 is formed on the source electrode 106 and the drain electrode 107, and the passivation layer 108 is indium tin oxide (ITO), which is a transparent conductive material for each pixel region defined by the intersection of the gate line and the data line, or A transparent electrode 109 made of IZO (Indium Zinc Oxide) or the like is formed. The transparent electrode 109 is connected to the drain electrode 107 through a contact hole (not shown) to receive an image signal to drive the liquid crystal molecules.

The reflective film 110 having the transmission window 111 is formed on the transparent electrode 109. The reflective film 110 is formed of a conductive film having a high reflectance such as aluminum or an aluminum alloy, and becomes a pixel electrode together with the transparent electrode 109. In this case, the transmission window 111 of the reflective film 110 may be formed in various shapes, a plurality of may be formed in one pixel area.

Next, the lower structure of the first insulating substrate 60 having the above-described structure will be described.

Reflecting projections 61 made of metal such as aluminum are formed on the lower surface of the first insulating substrate 60, and convex lenses 62 are formed on the lower surface of the first insulating substrate 60 on which the reflective projections 61 are formed. ) Is formed.

At this time, the reflection protrusion 61 is formed so as to overlap the TFT 51 in the reflection mode region A, thereby preventing light from entering the TFT 51 from the outside.                     

In addition, a convex lens 62 is formed in the pixel region where the reflection protrusion 61 is not formed to collect light so that the light emitted from the backlight unit 90 can go to the transmission mode region B as much as possible.

On the other hand, since the reflection protrusion 61 is formed in the portion where the convex lens 62 is not formed, all the light that has not passed through the convex lens 62 is reflected and returned to the backlight unit 90. The light is again reflected by the reflector in the backlight unit 90 so that a part passes through the convex lens 62 and a part proceeds to the part where the reflecting protrusion 61 is formed. This process is repeated so that most of the light enters the transmission mode region B through the convex lens 62. Therefore, the light utilization efficiency of the backlight unit 90 is maximized.

Hereinafter, a manufacturing process of the lower substrate for a transflective liquid crystal display device will be described.

3A to 3D are cross-sectional views illustrating a manufacturing process of a lower substrate for a transflective liquid crystal display according to an exemplary embodiment of the present invention.

First, as shown in FIG. 3A, a photosensitive film is coated on a lower surface of a lower substrate 60 made of a transparent material such as glass, and then exposed and developed to expose the lower substrate in a state in which the reflection mode region A and its peripheral region are exposed. The 60 is etched to form a convex lens 62 that is a light collecting portion.

At this time, a portion of the convex lens 62 into which the light emitted from the backlight unit (outside) directly enters the transmission mode region B is formed flat, while the convex lens 62 enters the reflection mode region A. The other area of may be formed by varying spherical aberration, thereby adjusting the amount of light through angle adjustment of the convex lens 62.

Next, as shown in FIG. 3B, a metal film made of aluminum (Al) or the like is deposited on the lower surface of the lower substrate 60, and a photoresist film is coated on the metal film, and then a photolithography process using the photoresist film is used to reflect the metal material. The protrusion 61 is formed.

In this case, the metal film is removed from the transmission mode region B and a part of the reflection mode region A surrounding the lower substrate 60 to expose the surface of the lower substrate 60. In addition, the reflection protrusion 61 is formed to overlap the plurality of TFTs in the liquid crystal cell, thereby preventing light from flowing into the TFT from the outside.

Next, as shown in FIG. 3C, the lower polarizer 70 is attached to the lower surface of the lower substrate 60 on which the reflecting protrusion 61 and the convex lens 62 are formed, and then, λ on the lower surface of the lower polarizer 70. The lower compensation film 80 which consists of / 2 or (lambda) / 4 reflective film, etc. is attached.

Next, as shown in FIG. 3D, the backlight unit 90, which is a light source, is attached to the lower surface of the lower compensation film 80. At this time, before the backlight unit 90 is attached, the prism sheet may be additionally attached to adjust the light inflow amount into the transmission mode region B. FIG.

The drawings and detailed description of the invention are merely exemplary of the invention, which are used for the purpose of illustrating the invention only and are not intended to limit the scope of the invention as defined in the claims or in the claims. That is, those skilled in the art will be able to easily derive various modifications and equivalent other embodiments therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

In the present invention, by forming the light reflecting projection on the lower surface of the lower substrate so as to overlap the TFT, it is possible not only to prevent light from entering the reflection mode region but also to use the predetermined reflecting plate and convex lens to reflect the light reflected from the reflecting projection. By sending the light into the transmission mode region in the liquid crystal cell, the light utilization efficiency can be improved as a whole.

Claims (13)

A first insulating substrate; A second insulating substrate facing the first insulating substrate and having two regions divided into a reflection mode region and a transmission mode region; A liquid crystal layer that is injection-sealed between the first insulating substrate and the second insulating substrate; Upper and lower polarizers attached to front and rear surfaces of the liquid crystal layer, respectively; A reflection protrusion formed on a bottom surface of the second insulating substrate; And Condensing part formed in the lower surface of the said 2nd insulating board, and is formed in the area | region other than the part in which the said reflective projection is formed. Transflective liquid crystal display device comprising a. According to claim 1, The light collecting part is a convex lens, and the convex lens is formed by partially etching the second insulating substrate. According to claim 1, And a prism sheet attached to a lower surface of the lower polarizer and configured to control an amount of light flowing into the transmission mode region of the second insulating substrate. According to claim 1, And a light source formed at a rear side of the lower polarizer and supplying light, wherein the light source includes a reflector for reflecting a part of light reflected from the reflecting protrusion. Insulation board, A first signal line formed on the insulating substrate; A first insulating film formed on the first signal line; A second signal line formed on the first insulating film and crossing the first signal line; A thin film transistor connected to the first signal line and the second signal line; A second insulating film formed on the thin film transistor and having a first contact hole for exposing a predetermined electrode of the thin film transistor; A transparent electrode formed on the second insulating layer and connected to a predetermined electrode of the thin film transistor through the first contact hole; A reflective electrode formed on the transparent electrode and having a transmission window; A reflection protrusion formed on a bottom surface of the insulating substrate and overlapping the thin film transistor; And A convex lens formed on a lower surface of the insulating substrate and overlapping a portion of the transmission window and the transparent electrode. Transistor substrate for a transflective liquid crystal display comprising a. A first insulating substrate; A second insulating substrate facing the first insulating substrate and having two regions divided into a reflection mode region and a transmission mode region; A liquid crystal layer that is injection-sealed between the first insulating substrate and the second insulating substrate; Upper and lower polarizers attached to front and rear surfaces of the liquid crystal layer, respectively; And Reflective protrusions formed on at least a portion of the lower surface of the second insulating substrate in the reflective mode region Transflective liquid crystal display device comprising a. The method of claim 6, A semi-transmissive liquid crystal display device, which is formed in the remaining region except for the portion where the reflective protrusions are formed, and further includes a condenser formed of a convex lens. The method of claim 6, And a prism sheet attached to a lower surface of the lower polarizer and configured to control an amount of light flowing into the transmission mode region of the second insulating substrate. The method of claim 6, And a light source formed at a rear side of the lower polarizer and supplying light, wherein the light source includes a reflector for reflecting a part of light reflected from the reflecting protrusion. A first insulating substrate; A second insulating substrate facing the first insulating substrate and having two regions divided into a reflection mode region and a transmission mode region; A liquid crystal layer that is injection-sealed between the first insulating substrate and the second insulating substrate; Upper and lower polarizers attached to front and rear surfaces of the liquid crystal layer, respectively; And A light collecting part formed on at least a lower surface of the second insulating substrate in the transmission mode region and including a convex lance. Transflective liquid crystal display device comprising a. The method of claim 10, A transflective liquid crystal display device further comprising a reflection protrusion formed on at least a lower surface of the second insulating substrate in the reflection mode region. The method of claim 10, And a prism sheet attached to a lower surface of the lower polarizer and configured to control an amount of light flowing into the transmission mode region of the second insulating substrate. The method of claim 10, And a light source formed at a rear side of the lower polarizer and supplying light, wherein the light source includes a reflector for reflecting a part of light reflected from the reflecting protrusion.

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