KR20070001488A - Transflective type liquid crystal display device - Google Patents

Abstract

A transflective LCD(Liquid Crystal Display) is provided to improve transmission characteristic by forming unit pixels including RGB sub-pixels having a reflection part and a transmission part and a white sub-pixel having only the transmission part. A transflective LCD includes unit pixels having at least one first sub-pixel(R,G,B) and at least one second sub-pixel(W). The first sub-pixel includes a transmission part(RTP,GTP,BTP) that transmits light emitted from a back light unit and a reflection part(RRP,GRP,BRP) that reflects an external light. The second sub-pixel has only a transmission part(WTP) for transmitting the light from the back light unit. The first sub-pixel includes a red sub-pixel, a green sub-pixel and a blue sub-pixel. The second sub-pixel is a transmissive white sub-pixel. The first sub-pixel includes a transparent pixel electrode formed in the transmission part, an opaque reflection electrode(60) formed in the reflection part, and a color filter layer formed opposite to the transmission part and the reflection part. The second sub-pixel includes a transparent pixel electrode formed in the transmission part.

Description

Transflective liquid crystal display {TRANSFLECTIVE TYPE LIQUID CRYSTAL DISPLAY DEVICE}

1 is a plan view showing a unit pixel of a transflective liquid crystal display according to the related art.

2 is a plan view illustrating a unit pixel of a transflective liquid crystal display according to a first exemplary embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view taken along the line II ′ of FIG. 2.

4 is a cross-sectional view schematically illustrating a red subpixel of the three color subpixels illustrated in FIG. 2.

FIG. 5 is a schematic cross-sectional view of the white subpixel illustrated in FIG. 2. FIG.

6 is a graph illustrating a comparison between transmission and reflection characteristics of a related art and a transflective liquid crystal display according to an exemplary embodiment of the present invention.

7 is a graph illustrating a comparison between transflective characteristics of a related art and a transflective liquid crystal display according to an exemplary embodiment of the present invention.

8 is a plan view illustrating a unit pixel of a transflective liquid crystal display according to a second exemplary embodiment of the present invention.

FIG. 9 is a schematic cross-sectional view taken along the line II-II ′ of FIG. 8;

10 is a plan view illustrating a unit pixel of a transflective liquid crystal display according to a third exemplary embodiment of the present invention.

11 is a plan view illustrating a unit pixel of a transflective liquid crystal display according to a fourth exemplary embodiment of the present invention.

<Explanation of Signs of Major Parts of Drawings>

17 pixel electrode 23 color filter layer

24: through hole 60: reflective electrode

RTP: Red Transmitter RRP: Red Reflector

GTP: Green Transmissive GRP: Green Reflective

BTP: Blue Transmitter BRP: Blue Reflector

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a transflective liquid crystal display device capable of improving transmission characteristics.

Since the liquid crystal display is not a self-light emitting device, a separate light source is required. The liquid crystal display may be classified into a transmissive type and a reflective type according to a light source.

In the transmissive liquid crystal display, a backlight unit is installed to face a lower substrate of two transparent substrates into which liquid crystal is injected to transmit light incident from the backlight unit toward the display surface. On the other hand, the reflective liquid crystal display device forms a reflective surface on the lower substrate of the two transparent substrates into which the liquid crystal is injected to display the display surface, that is, the external light incident on the lower substrate via the upper substrate or a separate auxiliary light. It is reflected toward.

On the other hand, in recent years, research into a transflective liquid crystal display device which may have advantages of a transmissive type and a reflective type is being activated.

The transflective liquid crystal display operates as a reflective liquid crystal display by reflecting light incident from the outside by a reflective electrode when the external light is sufficient, and by using a backlight unit when the external light is insufficient. Light from the backlight unit is incident on the liquid crystal to operate as a transmissive liquid crystal display.

Meanwhile, the high brightness transflective liquid crystal display proposed by Korean Patent Laid-Open Publication No. 2005-37685 includes a color unit pixel CPX1 composed of four subpixels UPX1 of RGBW, as shown in FIG. Each subpixel UPX1 includes a hatched reflective region RR and other transmissive regions TR.

The reflection area RR of the RGB subpixels R, G, and B has the same area, whereas the reflection area RRW of the W subpixel W has a larger area than the transmission area TRW. In this case, the white color filter layer is formed larger in the reflection region RRW than in the transmission region TRW to minimize the display difference between the reflection mode and the transmission mode.

The high-luminance semi-transmissive liquid crystal display may adjust the area ratio of the reflective region RRW and the transparent region TRW in the white subpixel W to minimize the difference between the reflective display and the transmissive display. This can be optimized very easily compared to the method of reducing the display difference in.

However, such a high brightness semi-transmissive liquid crystal display device has a disadvantage in that its transmissive characteristic is reduced due to the area of the reflective region RRW even if the area ratio of the reflective region RRW and the transparent region TRW formed in the white subpixel W is adjusted. .

Therefore, the high brightness transflective liquid crystal display according to the related art has a problem that it is not suitable for the transflective liquid crystal display which requires the improvement of the transmissive property rather than the reflection characteristic.

Accordingly, in order to solve the above problems, the present invention is to provide a transflective liquid crystal display device capable of improving the transmission characteristics.

In addition, another object of the present invention is to provide a transflective liquid crystal display device capable of improving transmission characteristics and improving reflection characteristics.

A semi-transmissive liquid crystal display device according to an embodiment of the present invention for achieving the above object includes at least one first subpixel having a transmission portion for transmitting the light from the backlight unit and a reflection portion for reflecting external light; And a unit pixel including at least one second subpixel having only a transmission unit for transmitting light from the backlight unit.

The first subpixel may include a red subpixel representing red, a green subpixel representing green, and a blue subpixel representing blue.

The second subpixel may be a transparent white subpixel representing white.

The first subpixel may include a transparent pixel electrode formed on the transmission part, an opaque reflection electrode formed on the reflection part, and a color filter layer facing the transmission part and the reflection part.

The second subpixel may include a transparent pixel electrode formed on the transmission part.

The transflective liquid crystal display may further include a transmission hole formed in the reflection unit.

The transmission hole may be formed in the color filter layer opposite to the reflector.

The unit pixels may be arranged in quad and stripe types.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings and embodiments.

FIG. 2 is a plan view showing one unit pixel in the transflective liquid crystal display according to the first exemplary embodiment of the present invention, and FIG. 3 is a schematic diagram cut along the line II ′ of FIG. 2. It is a cross section.

2 and 3, the transflective liquid crystal display according to the first embodiment of the present invention includes a transmissive portion (RTP, GTP, BTP) for transmitting light from the backlight unit and a reflecting portion for reflecting external light ( A unit pixel including at least one first subpixel RGB having RRP, GRP, and BRP, and at least one second subpixel W having a transmission part WTP through which light from the backlight unit is transmitted It is provided.

The first subpixel RGB includes a red subpixel R representing red, a green subpixel G representing green, and a blue subpixel B representing blue.

The red subpixel R transmits light from the backlight unit toward the display surface through the red color filter layer 23R to express red color, and external light is red by using the reflective electrode 60. A red reflector RRP is formed to reflect red through the color filter layer 23R toward the display surface. In this case, the red transmitting part RTP and the red reflecting part RRP have different areas, and the area ratio of the red transmitting part RTP and the red reflecting part RRP may be adjusted according to the transmission and reflection characteristics.

The green subpixel G transmits the light from the backlight unit toward the display surface through the green color filter layer 23G to express green, and external light is green by using the reflective electrode 60. A green reflecting part GRP is formed to reflect green through the color filter layer 23G toward the display surface. In this case, the green transmitting part GTP and the green reflecting part GRP may have different areas, and the area ratio of the green transmitting part GTP and the green reflecting part GRP may be adjusted according to the transmission and reflection characteristics.

The blue subpixel B transmits the light from the backlight unit toward the display surface through the blue color filter layer 23B to express blue, and external light is blue by using the reflective electrode 60. A blue reflecting portion BRP that reflects blue toward the display surface through the color filter layer 23B is provided. In this case, the blue transmitting part BTP and the blue reflecting part BRP have different areas, and the ratio of the area of the blue transmitting part BTP and the blue reflecting part BRP may be adjusted according to the transmission and reflection characteristics.

The second subpixel W is a white transmissive subpixel having a white transmissive portion WTP that transmits light from the backlight unit toward the display surface to represent white.

The three-color subpixel RGB and the white subpixel W are arranged in a quad type to form one unit pixel. That is, red and green subpixels R and G are disposed in the first horizontal direction, and blue and white subpixels B and W are disposed in the second horizontal direction.

4 is a cross-sectional view schematically illustrating a red subpixel among the three color subpixels illustrated in FIG. 2.

Referring to FIG. 4, the red subpixel R of the present invention includes a transistor array substrate 11, a color filter array substrate 21 facing the transistor array substrate 11, a transistor array substrate 11, and a color filter. It consists of liquid crystals 31 enclosed between the array substrates 21.

The transistor array substrate 11 includes a gate line (not shown) and a data line (not shown) that vertically cross each other to define a pixel region, and a gate electrode 12a and a gate insulating layer 13 at intersections of the two lines. A thin film transistor including a semiconductor layer 14, an ohmic contact layer 14a, and source / drain electrodes 15a and 15b, a protective film 16 formed on the entire surface of the transistor array substrate 11 including the thin film transistor, A transparent pixel electrode 17 connected to the thin film transistor and formed on the red transparent portion RTP on the passivation layer 16, an interlayer insulating layer 18 formed on the entire surface of the transistor array substrate 11 including the pixel electrode 17, and a thin film. It is composed of an opaque reflective electrode 60 connected to the transistor and formed in the reflective portion RRP on the interlayer insulating film 18.

The color filter array substrate 21 includes a black matrix 22 for blocking light leakage, a red (R) color filter layer 23 formed between the black matrix 22, and a pixel electrode 17 of the transistor array substrate 11. And a common electrode 91 facing the reflective electrode 60.

Meanwhile, first and second alignment layers (not shown) and transistor array substrates (not shown) are arranged on inner surfaces of the transistor array substrate 11 and the color filter array substrate 21 to arrange molecules of the liquid crystal 31 in a predetermined direction. 11) and a phase difference plate 54 disposed on the outer surface of the color filter array substrate 21, between the first and second polarizing plates 50 and 51, and the color filter array substrate 21 and the second polarizing plate 51. It is further provided.

The first and second polarizing plates 50 and 51 pass only light in a direction parallel to the light transmission axis to convert natural light into linearly polarized light. The phase difference plate 54 functions to change the polarization state of the light by delaying the incident linear flat light by 180 ° by using a phase difference corresponding to lambda / 2.

The red subpixel R transmits the light irradiated from the backlight unit to the red transmitting part RTP through the red color filter layer 23 to the display surface according to the electric field between the pixel electrode 17 and the common electrode 91. Or reflect external light incident from the outside according to the electric field between the pixel electrode 17 and the reflective electrode 60 to the reflective electrode 60 of the red reflector RRP, and display the light through the red color filter layer 23. Is transmitted through. Accordingly, the red subpixel R expresses red according to the red light passing through the red color filter layer 23 of the red transmitting part RTP or the red reflecting part RRP.

Meanwhile, the green and blue subpixels G and B have the same structure as the above-described red subpixel R except for the color filter layer 23.

The green subpixel G transmits the light irradiated from the backlight unit to the green transmission part GTP from the backlight unit to the display surface through the green color filter layer 23 according to the electric field between the pixel electrode 17 and the common electrode 91. In response to the electric field between the pixel electrode 17 and the reflecting electrode 60, external light incident from the outside is reflected by the reflecting electrode 60 of the green reflecting unit GRP and transmitted to the display surface through the green color filter layer 23. Let's go. Accordingly, the green subpixel G expresses green according to the green light transmitted through the green color filter layer 23 of the green transmitting part GTP or the green reflecting part GRP.

The blue subpixel B transmits the light irradiated from the backlight unit to the blue transmission part BTP through the blue color filter layer 23 to the display surface according to the electric field between the pixel electrode 17 and the common electrode 91. The external light incident from the outside according to the electric field between the pixel electrode 17 and the reflective electrode 60 is reflected by the reflective electrode 60 of the blue reflector BRP and transmitted to the display surface through the blue color filter layer 23. Let's go. Accordingly, the blue subpixel B expresses blue according to the blue light transmitted through the blue color filter layer 23 of the blue transmitting part BTP or the blue reflecting part BRP.

FIG. 5 is a cross-sectional view schematically illustrating the white subpixel illustrated in FIG. 2.

Referring to FIG. 5, the white subpixel W of the present invention is formed on the front surface of the white transmissive portion WTP and connected to the pixel electrode 17 connected to the thin film transistor, and the color filter array substrate 21 facing the white transmissive portion WTP. ) Has the same structure as the above-described three-color subpixel RGB except that there is no color filter layer.

Accordingly, the white subpixel W transmits light incident from the backlight unit to the white transmission portion WTP toward the display surface.

Meanwhile, a white color filter layer may be formed on the color filter array substrate 21 facing the white transmissive portion WTP in the white subpixel W.

6 is a graph illustrating a comparison of transmission and reflection characteristics of a related art and a transflective liquid crystal display according to an exemplary embodiment of the present invention.

In Figure 6 the horizontal axis represents the area of the transmission portion, the vertical axis represents the transmission / reflection characteristics. As shown in FIG. 6, it can be seen that the transmissive and reflective properties of the transflective liquid crystal display according to the exemplary embodiment of the present invention are improved as compared with related arts.

7 is a graph illustrating a comparison between semi-transmissive characteristics of a related art and a transflective liquid crystal display according to an exemplary embodiment of the present invention.

In Figure 7, the horizontal axis represents the area of the transmission portion, the vertical axis represents the transmission / reflection characteristics. As shown in FIG. 7, it can be seen that the transflective property of the transflective liquid crystal display according to the exemplary embodiment of the present invention is improved compared to the related art.

FIG. 8 is a plan view illustrating one unit pixel in the transflective liquid crystal display according to the second exemplary embodiment of the present invention, and FIG. 9 is a schematic diagram cut along the line II-II ′ of FIG. 8. It is a cross section.

8 and 9, a transflective liquid crystal display according to a second exemplary embodiment of the present invention includes a transmissive portion (RTP, GTP, BTP) for transmitting light from a backlight unit and a reflecting portion for reflecting external light ( At least one first subpixel RGB having RRP, GRP, BRP and transmission holes 24 formed in the reflecting portions RRP, GRP, BRP, and a transmission portion WTP for transmitting light from the backlight unit. It has a unit pixel including at least one second sub-pixel (W) having a).

The transflective liquid crystal display according to the second exemplary embodiment of the present invention has the exception of the transmissive holes 24 formed in the reflecting portions RRP, GRP, and BRP of the first subpixel RGB. It has the same structure as the transflective liquid crystal display according to the first embodiment of the present invention shown in FIG. Accordingly, in the transflective liquid crystal display according to the second embodiment of the present invention, only the description of the transmissive hole 24 will be described, and the description of other configurations will be replaced with the description of the first embodiment of the present invention. do.

The transmissive hole 24 is a color filter layer 23R of each of the red subpixel R, the green subpixel G, and the blue subpixel B facing the reflective electrode 60 of the reflecting portions RRP, GRP, and BRP. , 23G, 23B). Each of the transmission holes 24 improves the reflectance by increasing the incident amount of external light incident on the reflective electrode 60 through the color filter layers 23R, 23G, and 23B from the outside.

The transflective liquid crystal display according to the second exemplary embodiment of the present invention improves the transmission characteristics by using the white transmissive subpixel W having only the white transmissive portion WTP and also transmits the reflective portions RRP, GRP, and BRP. The hole 24 may be formed to improve reflection characteristics.

10 is a plan view illustrating one unit pixel in the transflective liquid crystal display according to the third exemplary embodiment of the present invention.

Referring to FIG. 10, the transflective liquid crystal display according to the third exemplary embodiment of the present invention includes at least one transmissive portion TP for transmitting light from the backlight unit and a reflecting portion RP for reflecting external light. At least one second subpixel W having a first subpixel RGB and a transmissive portion TP through which light from the backlight unit is transmitted is provided.

The transflective liquid crystal display according to the third exemplary embodiment of the present invention has the same structure as the first exemplary embodiment of the present invention except that the unit pixels are arranged in a stripe form.

11 is a plan view illustrating one unit pixel in the transflective liquid crystal display according to the fourth exemplary embodiment of the present invention.

Referring to FIG. 11, a transflective liquid crystal display according to a fourth exemplary embodiment of the present invention includes a transmissive portion TP for transmitting light from a backlight unit, a reflecting portion RP for reflecting external light, and a reflecting portion RP. ) At least one first subpixel RGB having a transmission hole 24 formed in the cross-section, and at least one second subpixel W having a transmission portion WTP for transmitting light from the backlight unit. It has a unit pixel arranged in the form.

The transflective liquid crystal display according to the fourth embodiment of the present invention has the same structure as the second embodiment of the present invention except that the unit pixels are arranged in a stripe form.

On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is possible that various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention It will be apparent to those skilled in the art.

As described above, the transflective liquid crystal display according to the exemplary embodiment of the present invention may improve transmission characteristics by including a unit pixel including three color subpixels having a reflection part and a transmission part and a white subpixel having only the transmission part. In addition, the transflective liquid crystal display according to the exemplary embodiment of the present invention improves transmission characteristics and reflection characteristics by including a three-color subpixel having a reflection portion and a transmission portion, a white subpixel having only the transmission portion, and a transmission hole formed in the reflection portion. You can.

As a result, the transflective liquid crystal display according to the exemplary embodiment of the present invention may improve visibility due to improvement of reflection and transmission characteristics.

Claims (8)

And at least one first subpixel having only a transmissive part transmitting light from the backlight unit and a reflecting part reflecting external light, and at least one second subpixel having only a transmitting part transmitting light from the backlight unit. Semi-transmissive liquid crystal display device comprising a unit pixel. The method of claim 1, The first subpixel is, A red subpixel representing red, A green subpixel representing green, A semi-transmissive liquid crystal display device comprising a blue subpixel representing blue. The method of claim 1, The transflective liquid crystal display of claim 2, wherein the second subpixel is a transparent white subpixel representing white. The method of claim 1, The first subpixel is, A transparent pixel electrode formed on the transmission part; An opaque reflective electrode formed on the reflective portion, And a color filter layer facing the transmissive portion and the reflecting portion. The method of claim 4, wherein The second subpixel may include a transparent pixel electrode formed on the transmissive portion. The method of claim 4, wherein The transflective liquid crystal display device further comprising the through-hole formed in the said reflecting part. The method of claim 6, The transmissive hole is a transflective liquid crystal display, characterized in that formed in the color filter layer facing the reflecting portion. The method of claim 1, The unit pixel is a semi-transmissive liquid crystal display, characterized in that arranged in quad and stripe type.

Images