JP2000267081A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal display device capable of efficiently using backlight for a transmissive display in dark space, besides, efficiently using external light for a reflective display in bright space, reproducing excellent colors in both cases and reducing the power consumption. SOLUTION: A reflection part PR and a transmission part PT are provided in one pixel region P. In a bright space, pictures are displayed by selectively reflecting external light with the reflection part PR. In a dark space, the pictures are displayed by selectively transmitting backlight emitted from a backlight unit 30 with the transmission part PR. Film thickness of a color filter CFR in the reflection part PR is made thinner than that of a color filter CFT in the transmission part PT. Thereby, a spectral transmission factor of the color filter CFR is made higher than that of the color filter CFT.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a reflective portion for displaying an image by reflecting external light in one pixel region and displaying an image by transmitting backlight light. The present invention relates to a transflective color liquid crystal display device having a transmissive portion.

[0002]

2. Description of the Related Art In general, a liquid crystal display device has a switching element arranged near an intersection of a scanning line and a signal line arranged orthogonally to each other, and a pixel electrode electrically connected to the switching element. An array substrate, a counter substrate having a counter electrode, and a liquid crystal composition sandwiched between the array substrate and the counter substrate are provided. In addition to these components, the color liquid crystal display device includes, for example, a color filter having a substantially uniform film thickness on the array substrate side.

[0005] A transflective color liquid crystal display device includes a reflective portion and a transmissive portion in one pixel region. The reflection section has a reflection electrode such as an aluminum film disposed below the color filter. The transmissive portion has a transmissive electrode such as an indium-tin-oxide, ie, an ITO film, which is disposed on a color filter having substantially the same thickness as the reflective portion. The reflection electrode and the transmission electrode are pixel electrodes connected to the switching element, and are supplied with the same voltage.

In such a transflective color liquid crystal display device, a backlight is turned on in a dark place, and the transflective color liquid crystal display device functions as a transmissive liquid crystal display device that displays an image by using a transmissive portion in a pixel area, thereby providing a bright light. In some cases, there is an advantage that power consumption can be significantly reduced by functioning as a reflective liquid crystal display device that displays an image by reflecting external light using a reflective portion in a pixel region.

[0005]

However, such a transflective liquid crystal display device has the following problems. That is, when displaying an image by reflecting external light,
External light passes twice through the color filter provided on the reflective electrode. On the other hand, when displaying an image by transmitting the backlight, the backlight passes only once through a color filter provided below the transmission electrode.

When the film thickness of the color filter is uniform in both the reflection part and the transmission part in the pixel area, that is, when the optical density of the color filter in the reflection part and the transmission part is constant, the reflection display is compared with the transmission display. As a result, the optical density is about twice as high, and the luminance is significantly reduced. For this reason, the color reproduction range at the time of reflective display becomes extremely small. Therefore, it is difficult to achieve good color reproduction at the time of both transmissive display and reflective display.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. It is an object of the present invention to effectively utilize backlight light for transmissive display in a dark place, and to provide an external light for reflective display in a bright place. It is an object of the present invention to provide a liquid crystal display device capable of effectively utilizing light to enable good color reproduction and reducing power consumption.

[0008]

In order to solve the above-mentioned problems and to achieve the object, a liquid crystal display device according to the first aspect of the present invention comprises a scanning line arranged in a row direction on one main surface, and a plurality of scanning lines. A pixel including a signal line arranged in a column direction so as to be orthogonal, a switching element disposed at an intersection of the scanning line and the signal line, and a reflective electrode and a transmissive electrode electrically connected to the switching element A first substrate having electrodes,
A liquid crystal display device comprising: a second substrate having a counter electrode disposed on one main surface; and a liquid crystal composition sandwiched between the first substrate and the second substrate. The pixel region partitioned by the line includes a reflective portion having a color filter and a reflective electrode, and a transmissive portion having a color filter and a transmissive electrode, and the optical density of the color filter of the reflective portion is equal to that of the transmissive portion. The optical density is different from the optical density of the color filter.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the liquid crystal display device of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view schematically showing an example of a liquid crystal display panel applied to the liquid crystal display device of the present invention.

A liquid crystal display according to an embodiment of the present invention is an active matrix type transflective color liquid crystal display, and includes a liquid crystal display panel 10 and a backlight unit 30.

As shown in FIG. 1, the liquid crystal display panel 10 has an array substrate 100 as a first substrate, an opposing substrate 200 as a second substrate arranged opposite to the array substrate 100, and an opposing substrate. A liquid crystal composition disposed between the substrate and the substrate. In such a liquid crystal display panel 10, a display area 1 for displaying an image is provided.
Numeral 02 is formed in a region surrounded by a sealant 106 for bonding the array substrate 100 and the counter substrate 200, and includes a plurality of pixel regions. Peripheral area 1 having various wiring patterns drawn out of display area 102
04 is formed in a region outside the sealing material 106.

The display area 102 of the array substrate 100 is
As shown in FIGS. 2 to 4, mxn pixel electrodes 151 arranged in a matrix on a transparent insulating substrate, for example, a glass substrate 101 having a thickness of 0.7 mm, are arranged in a row direction of the pixel electrodes 151. M scanning lines Y1 formed along
To Ym, n signal lines X1 to Xn formed along the column direction of these pixel electrodes 151, and mxn pixel electrodes 15
1, scanning lines Y1 to Ym and signal lines X1 to Xn
M × n thin film transistors or TFTs 12 arranged as non-linear switching elements near the intersection of
1. a scanning line driving circuit 18 for driving the scanning lines Y1 to Ym;
A signal line driving circuit 19 for driving these signal lines X1 to Xn
have.

The scanning lines are formed of a low-resistance material such as aluminum or a molybdenum-tungsten alloy. The signal line is formed of a low resistance material such as aluminum.

As shown in FIGS. 3 and 4, the pixel area P
Generally corresponds to a region defined by the scanning lines Y and the signal lines X provided on the array substrate 100. The one pixel region P includes a reflecting portion PR for displaying an image by selectively reflecting external light, and a transmitting portion PT for displaying an image by selectively transmitting backlight light from the backlight unit 30. have.

In each of these pixel regions, a color filter CF colored in three primary colors is provided in order to realize color display. In this embodiment, for example, a red pixel area, a green pixel area, and a blue pixel area have red, green,
A color filter CF colored blue is provided.
The color filter 203 is formed of, for example, a resin in which pigments of each color component are dispersed.

The backlight unit 30 shown in FIG.
Are arranged on the back surface of the array substrate 100 in the liquid crystal panel 10. The backlight unit 30 includes a light guide plate having a wedge-shaped cross section, a light source disposed on one side of the light guide plate, a reflection plate surrounding the light source, a prism sheet disposed between the light guide plate and the array substrate, and the like. And the like.

The reflecting portion PR includes a bump 161 formed of, for example, an acrylic resin resist and the bump 16.
And a reflection electrode 151R formed of a metal reflection film of aluminum or the like provided on the reflection electrode 151R. A color filter CFR is provided on the reflective electrode 151R.

The transmission part PT includes a color filter CFT,
A transmission electrode 151T formed of a transparent conductive member such as indium-tin-oxide, that is, ITO, provided on the color filter CFT. The transmission electrode 151T is connected to the reflection part PR and the transmission part P.
It is arranged over the entirety of one pixel region including T.

The reflection electrode 151R and the transmission electrode 151T
Functions as a pixel electrode 151 electrically connected to the source electrode of the TFT 121.

The thickness d1 of the color filter CFR in the reflection part PR is equal to the thickness d2 of the color filter CFT in the transmission part PT.
It is thinner and the ratio d1 / d2 between the film thicknesses d1 and d2 is less than 1. In the transmission part PT, the backlight light passes through the color filter CFT only once, while the reflection part PR
Then, the external light from the counter substrate 200 side is
FR passes twice, so the color filter C
It is preferable that the film thickness d1 of the FR be approximately の of the film thickness d2 of the color filter CFT.

As described above, by making the film thickness of the color filter CFR in the reflection part PR smaller than the film thickness of the color filter CFT in the transmission part PT, the optical density of the color filter CFR is different from the optical density of the color filter CFT. In contrast, a spectral transmittance as shown in FIG. 5 is obtained.

In FIG. 5, the thin line indicates the spectral transmittance of the color filter CFR in the reflection part PR, and the thick line indicates the transmission part P.
4 shows the spectral transmittance of the color filter CFT at T.

As shown in FIG. 5, the spectral transmittance RR of the red color filter in the reflecting portion PR is higher than the spectral transmittance RT of the red color filter in the transmitting portion PT. Further, the spectral transmittance GR of the green color filter in the reflection part PR is higher than the spectral transmittance GT in the transmission part PT. Further, the spectral transmittance BR of the blue color filter in the reflection part PR is equal to the spectral transmittance BT in the transmission part PT.
taller than.

As described above, by making the film thickness of the color filter CFR in the reflection part PR smaller than the film thickness of the color filter CFT in the transmission part PT, a smaller optical density, that is, a higher spectral transmittance is obtained. .

The TFT 121 has a portion protruding from the scanning line Y as a gate electrode, and has a semiconductor film formed of an amorphous silicon film, a polysilicon film, or the like laminated thereon with a gate insulating film interposed therebetween. The semiconductor film is a pixel electrode 1 via a low-resistance semiconductor film and a source electrode.
51 are electrically connected. The semiconductor film is electrically connected to a drain electrode extending from the signal line X via a low-resistance semiconductor film. In the example shown in FIGS. 3 and 4, the TFT 121 is disposed below the bump 161 near the intersection of the signal line X and the scanning line Y.

Reflective electrode 151R as pixel electrode 151
Are in contact with and electrically connected to the source electrode via contact holes formed in the bump 161 on the source electrode of the TFT 121. Also, the pixel electrode 151
The transmission electrode 151T is electrically connected to the source electrode via a contact hole formed in the bump 161 on the source electrode of the TFT 121 and the color filter CFR.

The surface of the transmission electrode 151T is
0, and is covered with an alignment film 141 for aligning the liquid crystal composition 300 interposed therebetween.

Each of the TFTs 121 has a potential of the signal lines X1 to Xn driven by the signal line driving circuit 19 when the corresponding scanning line is driven by the scanning line driving circuit 18 and the pixel electrode 151 of the corresponding row is selected. Is applied to the pixel electrodes 151 in the corresponding rows.

The scanning line driving circuit 18 supplies a scanning voltage to the scanning lines Y1 to Ym sequentially in a horizontal scanning cycle, and the signal line driving circuit 19 supplies a pixel signal voltage to the signal lines X1 to Xn in each horizontal scanning cycle. I do.

In the liquid crystal display panel 10, as shown in FIG. 1, although not shown in detail, the signal lines are arranged around the periphery of the array substrate 100 in order to reduce the outer dimensions of the liquid crystal display device, particularly the frame size. The X-TAB 401-is pulled out only to the first end side 100X side of the area 104X and is connected to the X control circuit board 421 including the signal line driving circuit 19 for supplying video data to the signal lines on the first end side 100X side.
1, 401-2, 401-3, and 401-4.

The scanning lines are also drawn out only to the second side 100Y of the peripheral area 104X of the array substrate, which is orthogonal to the first side 100X, and supply the scanning pulses to the scanning lines at the second side 100Y. Y-TAB 411-
1, 411-2.

As shown in FIGS. 2 to 4, the display area 102 of the counter substrate 200 includes a counter electrode 204 provided on a transparent insulating substrate, for example, a glass substrate 201 having a thickness of 0.7 mm. ing.

The opposing electrode 204 is formed of a transparent conductive member that forms a potential difference between the pixel electrode 151 and a transparent conductive member, for example, ITO.
Is formed by The surface of the counter electrode 204 is covered with an alignment film 205 for aligning the liquid crystal composition 300 interposed between the counter electrode 204 and the array substrate 100.

The counter electrode 204 includes a plurality of pixel electrodes 151.
Are set to the reference potential. An electrode transfer material, that is, a silver paste as a transfer, disposed around the substrate is provided to supply a voltage from the array substrate 100 to the counter substrate 200, and the counter electrode 204 is connected to the counter electrode drive connected via the transfer. Driven by the circuit 20.

A liquid crystal capacitor CL is formed by the liquid crystal layer 300 sandwiched between the pixel electrode 151 and the counter electrode 204.

The array substrate 100 includes a pair of electrodes for forming an auxiliary capacitance CS electrically in parallel with the liquid crystal capacitance CL. That is, the storage capacitor CS is connected to the pixel electrode 15
1 is formed by a potential difference formed between the storage capacitor electrode 61 having the same potential as 1 and the storage capacitor line 52 set to a predetermined potential.

On the outer surface of the glass substrate 101 of the array substrate 100, a λ / 4 wavelength plate 181 and a polarizing plate 183 are provided. On the outer surface of the glass substrate 201 of the counter substrate 200, a diffusion plate 207, a λ / 4 wavelength plate 209, and a polarizing plate 211 are provided. For the polarizing surfaces of the polarizing plates 183 and 211, an optimal direction is selected according to the display mode of the liquid crystal display device, the twist angle of the liquid crystal composition, and the like.

The thickness of the liquid crystal layer between which the liquid crystal composition 300 is sandwiched, that is, the gap having a predetermined width formed between the array substrate 100 and the counter substrate 200 is determined by the wiring patterns of the signal lines X and the scanning lines Y, TFT 121, pixel electrode 15
1. Secured by spacers arranged in non-pixel areas such as peripheral picture frames.

In the example shown in FIG. 4, the thickness of the liquid crystal layer is about 5 μm in the transmission part PT of the pixel region P.

In the reflection part PR of the pixel area P, the reflection electrode 1
51R and about 1 to 5 μm below the reflective electrode 151R.
Is provided, the position of the lower surface of the color filter CFR in the reflection part PR is higher than the position of the lower surface of the color filter CFT in the transmission part PT by 1 to 5 μm. The thickness of the color filter CFR is
Although the thickness of the color filter CFT is about １ ／, the thickness of the bump 161 and the reflective electrode 151R is １ ／ or more of the thickness of the color filter CFT. In the example shown in FIG. 4, the thickness of the liquid crystal layer of the transmission part PT is generally １ ／, that is, about 2.0.
5 μm.

FIG. 6 shows an example of an optimum relationship between the thickness of the color filter CF and the thickness of the liquid crystal layer with respect to the height of the bump 161. In FIG. 6, a solid line L1 indicates the thickness of the color filter, and a broken line L2 indicates the thickness of the liquid crystal layer. According to the relationship shown in FIG. 6, in the transmission part PT, the thickness of the liquid crystal layer is 5 μm, and the color filter C
The thickness of the FT is about 3 μm. In the reflection part PR, the thickness of the liquid crystal layer is 2.5 μm, the thickness of the color filter CFR is about 1 μm, and the height of the bump 161 is about 5 μm.

Next, a method for manufacturing the liquid crystal display device will be described.

That is, a glass substrate 1 having a thickness of 0.7 mm
A multi-layer film of an aluminum or molybdenum-tungsten alloy film forming a scanning line Y including a gate electrode of the TFT 121 and an auxiliary capacitance electrode 52, a silicon oxide film and a silicon nitride film forming a gate insulating film,
For example, an amorphous silicon film, a low-resistance semiconductor film, an aluminum film for forming the signal line X, the source electrode 131, and the drain electrode 132 as the semiconductor film are formed and patterned.

As a result, a plurality of scanning lines Y arranged in a row direction on one main surface of the glass substrate 101, these scanning lines Y
And the switching elements 121 arranged at the intersections of the signal lines X and the scanning lines Y and the signal lines X which are arranged in the row direction so as to be orthogonal to.

Subsequently, on the entire surface of the glass substrate 101,
A transparent ultraviolet curable acrylic resin resist (manufactured by Fuji Hunt Technology Co., Ltd.) is applied to a thickness of 4 μm using a spinner and dried. Thereafter, the acrylic resin resist is exposed at a wavelength of 365 nm at an exposure amount of 100 mJ / cm ² using a photomask having a predetermined pattern corresponding to the reflection portion PR of each pixel region P. For 70 seconds. Then, by baking, the bump 161 having a thickness of 4 μm is formed.

Subsequently, the TFT 121 is formed on the bump 161.
A contact hole penetrating to the source electrode is formed.

Subsequently, an aluminum thin film is formed on the entire surface of the glass substrate 101 by a sputtering method. At this time, the contact hole of the bump 161 is also filled with aluminum, and the source electrode of the TFT 121 and the pixel electrode 15 are filled.
1R is electrically connected. After that, this aluminum thin film is patterned into a predetermined pixel electrode shape so as to remain on the bump 161. Thus, on the bump 161,
A reflection electrode, that is, a pixel electrode 151R is formed.

Subsequently, a color filter CF is formed on the entire surface of the glass substrate 101. That is, the glass substrate 10
A UV-curable acrylic resin resist (manufactured by Fuji Hunt Technology Co., Ltd.) in which a red pigment is dispersed is applied to the entire surface of 1 with a predetermined thickness using a spinner. At this time,
This acrylic resin resist is set to have a viscosity such that the film thickness at the reflection portion PR having the bump 161 is slightly smaller than the film thickness at the transmission portion PT without the bump 161, and preferably about 約. Has a viscosity of 10 cp.

After drying the acrylic resin resist, the resist is exposed at a wavelength of 365 nm at an exposure amount of 100 mJ / cm ² using a photomask having a shape corresponding to the red pixel region. Develop for seconds. Then, by firing, the red color filter C having a predetermined thickness is formed in the transmission part PT and the reflection part PR.
Form F.

Similarly, a green color filter CF in the green pixel region and a green color filter CF in the blue pixel region by using an ultraviolet-curable acrylic resin resist in which a green pigment is dispersed and an ultraviolet-curable acrylic resin resist in which a blue pigment is dispersed. The blue color filters CF are respectively formed.

Subsequently, a TFT is added to the color filter CF.
A contact hole penetrating to the source electrode 121 is formed.

Subsequently, the entire surface of the glass substrate 101
An O thin film is formed by a sputtering method. At this time,
The contact hole of the color filter CF is also filled with ITO, and the source electrode of the TFT 121 and the pixel electrode 151T are electrically connected. After that, the ITO thin film is patterned into a predetermined pixel electrode shape so as to remain in the entire one pixel region P. Thus, the transmission electrode, that is, the pixel electrode 15
Form 1T.

Subsequently, AL-1051 was used as an alignment film material.
An alignment film 141 is formed by applying (manufactured by Nippon Synthetic Rubber Co., Ltd.) over the entire surface and performing a rubbing treatment.

On the other hand, a glass substrate 201 having a thickness of 0.7 mm
A counter electrode 204 and an alignment film 205 are formed thereon, and a counter substrate 200 is formed. The alignment film 205 of the counter substrate 200 has an alignment axis in a direction orthogonal to the alignment axis of the alignment film 141 of the array substrate 100.

Subsequently, the sealing material 106 is printed along the periphery of the alignment film 205 of the counter substrate 200 except for the liquid crystal injection port. Further, from the array substrate 100 side, the counter substrate 20
An electrode transfer material for supplying a voltage to the 0-side counter electrode 204 is formed on the electrode transfer electrode around the seal member 106.

Subsequently, the array substrate 100 and the counter substrate 200 are arranged so that the alignment films 141 and 205 face each other, heated to cure the sealant 106, and bonded to the two substrates. At this time, a predetermined gap is formed between the array substrate 100 and the counter substrate 200.

Subsequently, the array substrate 10 is inserted through the liquid crystal injection port.
0 and the counter substrate 200 as a liquid crystal composition 300
LI-1565 (manufactured by E. Merck) with chiral agent S81
The liquid crystal to which 0.1 wt% is added is injected, and the liquid crystal injection port is sealed with an ultraviolet curable resin. The injected liquid crystal composition 300 has a twist angle of 9 due to the alignment film 141 on the array substrate 100 side and the alignment film 203 on the counter substrate 200 side.
A 0 degree nematic liquid crystal layer is formed.

The thickness of the liquid crystal layer depends on the reflection part PR of the pixel region P.
And the transmission part PT. In the reflection part PR, the thickness from the surface of the glass substrate 101 is larger than the transmission part PT because the color filter CFR is formed on the bump 161, and the thickness of the liquid crystal layer in the reflection part PR is 2.5 μm. On the other hand, the thickness of the liquid crystal layer in the transmission part PT is 5 μm.
m.

For this reason, in the transmission part PT, the backlight light incident on the liquid crystal layer from the array substrate side generates a phase difference of λ / 2 before transmitting to the opposite substrate side. In the reflection part PR, external light incident on the liquid crystal layer from the counter substrate side is λ in one way.
The reflected light generated by the reflection electrode 151R having a phase difference of / 4 reciprocates by λ / 2 before being emitted to the counter substrate side.
Is generated.

On the outer surface of the array substrate 100, a λ / 4 wavelength plate 181 and a polarizing plate 183 are laminated in this order.
In addition, a diffusion plate 207, λ /
The four-wavelength plate 209 and the polarizing plate 211 are stacked in this order.

The circularly polarized light generated by passing through the deflecting plate and passing through the phase difference plate turns ON / OF the voltage to the liquid crystal layer.
F converts the light into circularly polarized light in the forward or reverse direction.
Thereby, after passing through the phase difference plate again, the pass / non-pass of the polarizing plate is selected. By utilizing this, in a dark place, an image is displayed by selectively transmitting backlight light. In a bright place, an image is displayed by selectively reflecting external light.

As described above, the transflective liquid crystal display device includes the reflection portion PR and the transmission portion PT in one pixel region P, and selectively reflects external light by the reflection portion PR in a bright place to display an image. Function as a reflective liquid crystal display device that displays
The transmissive portion PT functions as a transmissive liquid crystal display device that selectively transmits the backlight emitted from the backlight unit 30 and displays an image, thereby always driving the backlight unit as a transmissive liquid crystal display device. Power consumption can be greatly reduced as compared with the case where the power consumption is reduced.

The thickness of the color filter CFR in the reflection part PR is set to be equal to the thickness of the color filter CFR in the transmission part PT.
By making the color filter CFR thinner than the FT and making the spectral transmittance of the color filter CFR higher than that of the color filter CFT, it is possible to effectively use external light even in the case of functioning as a reflective liquid crystal display device in a light place. It becomes possible. Therefore, even when functioning as a reflective liquid crystal display device, a good color reproduction range equivalent to that when functioning as a transmissive liquid crystal display device can be realized in a dark place.

Next, another embodiment of the present invention will be described. Note that the same components as those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIGS. 7 and 8, the array substrate 1
In FIG. 00, the reflection portion PR of the pixel region P is a pixel electrode 151 serving as a reflection electrode provided on the glass substrate 101.
R. In addition, the transmission part PT is provided on the glass substrate 10.
1 and a first color filter CF1 provided on the first color filter CF1, and a pixel electrode 151T as a transmission electrode provided on the first color filter CF1. The optical density of the first color filter CF1 is １ ／, and the thickness thereof is about 2.5 μm. Therefore, the transmission portion PT of the array substrate 100 is equivalent to the thickness of the first color filter CF1.
Is thick. That is, the first color filter CF1 plays the role of the bump 161 in the above-described embodiment shown in FIGS.

In the counter substrate 200, the reflection part PR and the transmission part PT of the pixel region P are formed by the second color filter CF2 provided on the glass substrate 201 and the opposite color filter CF2 provided on the second color filter CF2. And an electrode 204. The optical density of the second color filter CF2 is
It is almost the same as the first color filter CF1 and is ２,
Its thickness is about 2.5 μm. The pixel region P on the counter substrate 200 side is substantially flat.

The optical density of the transmitting portion of the pixel region P is equal to the sum of the optical densities of the first color filter CF1 and the second color filter CF2, and is 1. On the other hand, the optical density of the reflecting portion is Only the optical density of the two-color filter CF2 is effective, and is １ ／. At the time of transmissive display in a dark place, the backlight light incident on the array substrate side from the backlight unit selectively passes through the first color filter CF1 and the second color filter CF2. In a bright place, during reflective display, external light incident from the counter substrate side passes through the second color filter CF2, is reflected by the reflection electrode 151R, and selectively passes through the second color filter CF2 again.

As described above, the backlight light and the external light are
The light passes through a color filter having substantially the same optical density, so that the same color reproduction as in transmissive display can be realized even in reflective display.

The pixel region P of the opposing substrate 200 is substantially flat, while the pixel region P of the array substrate 100 has the first color filter CF1 in the transmissive portion PT.
Is thicker than the reflecting portion PR by the thickness of. Therefore, the reflecting portion P
The thickness of the liquid crystal layer of R is greater than the thickness of the liquid crystal layer of the transmission part PT. In this embodiment, the thickness of the liquid crystal layer of the reflection part PR is about 7.5 μm, and the thickness of the liquid crystal layer of the transmission part PT is about 5 μm.

For this reason, assuming that the phase difference that occurs in the transmission portion PT until the backlight light incident on the liquid crystal layer from the array substrate side is transmitted to the counter substrate side is λ / 2, the reflection portion PR has External light incident on the liquid crystal layer from
A phase difference of λ / 2 × 3/2 = 3λ / 4 is generated in one way, and a phase difference generated before the reflected light reflected by the reflective electrode 151R is emitted to the counter substrate side is 3λ / 2 in a round trip. .

On the outer surface of the array substrate 100, a λ / 4 wavelength plate 181 and a polarizing plate 183 are laminated in this order in the same manner as in the above-described embodiment. , Λ / 4 wavelength plate 209 and polarizing plate 211 are laminated in this order.

The circularly polarized light generated by passing through the polarizing plate and passing through the phase difference plate turns ON / OF the voltage to the liquid crystal layer.
F converts the light into circularly polarized light in the forward or reverse direction.
Thereby, after passing through the phase difference plate again, the pass / non-pass of the polarizing plate is selected. By utilizing this, in a dark place, an image is displayed by selectively transmitting backlight light. In a bright place, an image is displayed by selectively reflecting external light.

As described above, the color filter is used as a substitute for the bump, and as a result, the thickness of the color filter in the reflection part PR is made smaller than the thickness of the color filter in the transmission part PT. Similarly to the embodiment described, it is possible to greatly reduce power consumption, and even when functioning as a reflective liquid crystal display device, the same as when functioning as a transmissive liquid crystal display device is used. A good color reproduction range can be realized.

[0075]

As described above, according to the present invention, in a dark place, the backlight light for the transmissive display is effectively used, and in a bright place, the external light for the reflective display is effectively used. In both cases, a liquid crystal display device that enables good color reproduction and can reduce power consumption can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing an example of a liquid crystal display panel applied to a liquid crystal display device of the present invention.

FIG. 2 is a diagram schematically showing a configuration of a liquid crystal display device of the present invention.

FIG. 3 is a plan view schematically showing one pixel region of the liquid crystal display panel shown in FIG.

FIG. 4 is a cross-sectional view schematically showing a cross section when one pixel region shown in FIG. 3 is cut along line AB.

FIG. 5 is a diagram showing a spectral transmittance of a color filter applied to the liquid crystal display device of the present invention.
FIG. 4 shows the spectral transmittance of the color filter of the transmitting portion in one pixel region, and the thin line shows the spectral transmittance of the color filter of the reflecting portion.

FIG. 6 is a diagram illustrating a thickness (L1) of a color filter and a thickness (L2) of a liquid crystal layer with respect to a height of a bump, respectively.

FIG. 7 is a plan view schematically showing another pixel region of the liquid crystal display panel shown in FIG. 1;

8 is a cross-sectional view schematically showing a cross section when one pixel region shown in FIG. 7 is cut.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display panel 30 ... Backlight unit 100 ... Array substrate 121 ... Thin film transistor 151 ... Pixel electrode 151R ... Reflection electrode 151T ... Transmission electrode 161 ... Bump 200 ... Counter substrate 300 ... Liquid crystal composition P ... Pixel area PR ... Reflection part PT ... Transmissive part CF (T, R) ... Color filter CF (1,2) ... Color filter

Claims (11)

[Claims] 1. A scanning line arranged in a row direction on one main surface, a signal line arranged in a column direction orthogonal to these scanning lines, and arranged at an intersection of the scanning line and the signal line. A first substrate having a switching element, and a pixel electrode composed of a reflective electrode and a transmissive electrode electrically connected to the switching element; a second substrate having a counter electrode disposed on one main surface; In a liquid crystal display device comprising: a liquid crystal composition sandwiched between a first substrate and a second substrate, a pixel region partitioned by the scanning lines and the signal lines includes:
A reflection portion having a color filter and a reflection electrode; and a transmission portion having a color filter and a transmission electrode, wherein the optical density of the color filter of the reflection portion is different from the optical density of the color filter of the transmission portion. A liquid crystal display device characterized by the above-mentioned. 2. The liquid crystal display device according to claim 1, wherein the spectral transmittance of the color filter of the reflection section is higher than that of the color filter of the transmission section. 3. The liquid crystal display device according to claim 1, wherein the thickness of the color filter in the reflection section is smaller than the thickness of the color filter in the transmission section. 4. A film thickness d1 of a color filter of said reflection portion.
And the ratio d1 of the thickness d2 of the color filter of the transmission part
The liquid crystal display device according to claim 1, wherein / d2 is less than 1. 5. The liquid crystal display device according to claim 1, wherein the thickness of the color filter in the reflection section is substantially の of the thickness of the color filter in the transmission section. 6. A ratio dc1 / of a thickness dc1 of the liquid crystal composition sandwiched between the first substrate and the second substrate in the reflection portion and a thickness dc2 of the liquid crystal composition in the transmission portion.
dc2 is substantially (2N + 1) when N is a natural number.
2. The liquid crystal display device according to claim 1, wherein the ratio is 1/2. 7. The liquid crystal display device according to claim 1, wherein the position of the lower surface of the color filter in the reflection portion is higher than the position of the lower surface of the color filter in the transmission portion by 1 to 5 μm. 8. The liquid crystal display device according to claim 1, wherein the reflection section has a bump below the reflection type electrode. 9. The liquid crystal display device according to claim 8, wherein the bump has a thickness of 1 to 5 μm. 10. The first substrate, comprising: a bump, a reflective electrode provided on the bump, and a color filter provided on the reflective electrode in a reflective portion of the pixel region; 2. The liquid crystal display device according to claim 1, wherein the portion includes a color filter having a thickness greater than that of the color filter of the reflection portion, and a transmission electrode provided on the color filter. 11. The first substrate includes a reflection electrode in a reflection portion of the pixel region, a color filter in a transmission portion of the pixel region, and a transmission electrode provided on the filter. 2. The liquid crystal display device according to claim 1, wherein the second substrate includes a color filter having a substantially uniform film thickness, facing the reflection part and the transmission part of the pixel area. 3.