JP5110927B2 - Electro-optical device and electronic apparatus - Google Patents

Electro-optical device and electronic apparatus Download PDF

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JP5110927B2
JP5110927B2 JP2007078304A JP2007078304A JP5110927B2 JP 5110927 B2 JP5110927 B2 JP 5110927B2 JP 2007078304 A JP2007078304 A JP 2007078304A JP 2007078304 A JP2007078304 A JP 2007078304A JP 5110927 B2 JP5110927 B2 JP 5110927B2
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electrode
electro
region
liquid crystal
pixel
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JP2008241789A (en
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明秀 春山
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株式会社ジャパンディスプレイウェスト
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    • GPHYSICS
    • G02OPTICS
    • G02FDEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/13718Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on a change of the texture state of a cholesteric liquid crystal
    • GPHYSICS
    • G02OPTICS
    • G02FDEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/13731Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on a field-induced phase transition
    • GPHYSICS
    • G02OPTICS
    • G02FDEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1335Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528Polarisers
    • G02F2001/133543Cholesteric polarisers

Description

  The present invention relates to an electro-optical device and an electronic apparatus.

  An electro-optical device using electronic polarization due to the Kerr effect is known. The Kerr effect refers to a phenomenon that exhibits optical anisotropy having a magnitude proportional to the square of the electric field strength with the electric field direction as an axis when an electric field is applied. As an electro-optical substance exhibiting such a Kerr effect, for example, a liquid crystal material called a blue phase is known. A liquid crystal display device using a blue phase as a liquid crystal layer is known for its high response speed. The blue phase exhibits optical isotropy when no electric field is applied. When the blue phase is at a temperature within a predetermined range, an optical anisotropy proportional to the square of the electric field strength is exhibited when an electric field is applied to the blue phase.

  In recent years, electro-optical devices such as liquid crystal display devices are often used as display units of portable electronic devices such as mobile phones and portable information terminals. In general, as a liquid crystal display device used for a portable electronic device, a transflective type capable of reflective display and transmissive display is adopted. In particular, a horizontal electric field type liquid crystal display device is known to have a wide viewing angle. By using a blue phase as a liquid crystal layer in such a transverse electric field type transflective liquid crystal display device, an improvement in viewing angle and a high-speed response are possible (for example, see Patent Document 1).

In general, a horizontal electric field type liquid crystal display device has a configuration in which a liquid crystal layer is sandwiched between one opposed substrate and a pixel electrode and a counter electrode are provided on the other substrate. The normal liquid crystal phase has a characteristic that the change in orientation propagates to the surrounding liquid crystal molecules as the orientation of the liquid crystal molecules in the interface region changes. For this reason, when a lateral electric field is applied, the orientation of the liquid crystal molecules changes in the region to which the transverse electric field is applied, and this change in orientation propagates in the thickness direction of the liquid crystal layer. On the other hand, the blue phase has a characteristic that even if the alignment of one liquid crystal molecule changes, the change in alignment hardly propagates to surrounding liquid crystal molecules. For this reason, when a horizontal electric field is applied to the blue phase, the alignment of the liquid crystal molecules changes in the region where the horizontal electric field is applied, but the change in alignment is difficult to propagate to the region where the horizontal electric field is not applied. As a result, the orientation of liquid crystal molecules changes only in a local region to which a lateral electric field is applied, and exhibits optical anisotropy only in this local region.
JP 2006-3840 A

  In general, a transflective liquid crystal display device has different cell thicknesses (liquid crystal layer thicknesses) between a reflective display region and a transmissive display region in order to obtain a good display in both reflective display and transmissive display. A structure (so-called multi-gap structure) is employed. However, when a horizontal electric field is applied to the blue phase, the alignment of the liquid crystal can only be changed in a local region where the electric field is generated, so if the cell thickness exceeds a certain thickness, the electric field is applied to the entire liquid crystal molecules. Will not reach and the area will not contribute to brightness. Therefore, there is no need to form a multi-gap in the transmission / reflection region. However, when white display is performed in the reflective area (for example, a phase difference of λ / 4), the phase difference of the transmissive area is λ / 4, and the substantial refractive index level between the transmissive display area and the reflective display area. The phase difference (retardation) does not match.

  If the retardation does not match between the reflective display area and the transmissive display area, the light transmittance will be different between the two areas. Due to the difference in the light transmittance, the brightness of the display differs in both areas, which causes a contrast difference. If there is a difference in contrast between the reflective display area and the transmissive display area, the display characteristics are deteriorated. There is a similar problem not only in a liquid crystal display device using a blue phase but also in an electro-optical device using an electro-optical material that exhibits the Kerr effect. However, in a transflective electro-optical device using an electro-optical material that exhibits the Kerr effect, means for improving display characteristics is not clear for both reflective display and transmissive display.

  In view of the circumstances as described above, an object of the present invention is to provide an electro-optical device and an electronic apparatus having high display characteristics.

In order to achieve the above object, an electro-optical device according to the present invention includes a plurality of sub-displays each including a reflective display region that performs reflective display and a transmissive display region that performs transmissive display, with an electro-optical material layer sandwiched between a pair of substrates. An electro-optical device including a pixel region, wherein an electro-optical material forming an electro-optical material layer is optically isotropic when an electric field is not applied and is proportional to the square of the electric field strength when an electric field is applied In addition to exhibiting anisotropy and negative dielectric anisotropy, the transmissive display region includes a first electrode on one side of the pair of substrates, the first electrode, and the first substrate. A second electrode having a height higher than that of the first electrode, the third electrode and the height from the one substrate on the electro-optic material layer side of the one substrate in the reflective display region. A fourth electrode formed higher than the third electrode, and the first electrode And the second electrode, and the third electrode and the fourth electrode have a thickness of the electro-optical material layer sandwiched between the first electrode and the second electrode in the transmissive display region, and the third electrode and the fourth electrode in the reflective display region. It is formed to be thicker than the layer thickness of the electro-optical material layer sandwiched between the electrodes.

  The magnitude of retardation is defined by the product (Δnd) of the thickness (d) of the electro-optic material layer and the magnitude of optical anisotropy (Δn). In a so-called transflective electro-optical device provided with a reflective display region and a transmissive display region, light passes through the electro-optical material layer in the reflective display region twice. This means that the thickness of the electro-optic material layer in the reflective display area is substantially twice the thickness of the electro-optic material layer in the transmissive display area. Therefore, in a configuration that does not employ a multi-gap, the substantial retardation of the reflective display region is twice that of the transmissive display region. In contrast, by increasing the retardation of the transmissive display region, the substantial retardation of the transmissive display region can be made equal to the substantial retardation of the reflective display region.

  According to the present invention, the height from the one substrate in at least one of the first electrode and the second electrode on the transmissive display region side is from one substrate in the third electrode and the fourth electrode on the reflective display region side. Therefore, the range of the electric field applied to the portion of the electro-optical material layer sandwiched between the first electrode and the second electrode is sandwiched between the third electrode and the fourth electrode. The range of the electric field applied to the portion of the electro-optic material layer can be made wider.

Therefore, in the present invention can be greater than the re Polygonum Shon of the retardation of the transmissive display region reflective display region. By increasing the retardation of the transmissive display area, the substantial retardation of the transmissive display area can be made equal to the substantial retardation of the reflective display area, and light transmission between the reflective display area and the transmissive display area can be achieved. The difference in rate can be eliminated. Thereby, the difference in contrast between the reflective display area and the transmissive display area can be eliminated, and an electro-optical device with high display characteristics can be obtained.
In addition, the orientation of the portion exhibiting negative dielectric anisotropy can be regulated in a desired direction .

The electro-optical device, the sub-pixel region of the double number, a first sub-pixel region for displaying the first color light, includes a second sub-pixel region for displaying the second color light, the first sub the height of the first electrode及beauty second electrode from hand surface of the substrate that put the pixel region, the first electrode及beauty second electrode from the surface of the hand of the substrate that put in the second sub-pixel region It may be formed higher than the height .
According to the present invention, in the first sub-pixel region displaying the first color light, the first electrode and the second electrode from the surface of one substrate are compared with the second sub-pixel region displaying the second color light. Since the height is high, an optimal light transmittance can be obtained according to the type of color light. Thereby, an electro-optical device having high display characteristics can be obtained.

The electro-optical device, the sub-pixel region of the double number, a first sub-pixel region for displaying the first color light, includes a second sub-pixel region for displaying the second color light, the first sub the height of the third electrode及beauty fourth electrode from hand surface of the substrate that put the pixel region, the third electrode及beauty fourth electrode from the surface of the hand of the substrate that put in the second sub-pixel region It may be formed higher than the height .
According to the present invention, in the first sub-pixel region displaying the first color light, the third electrode and the fourth electrode from the surface of one substrate are compared with the second sub-pixel region displaying the second color light. Since the height is high, an optimal light transmittance can be obtained according to the type of color light. Thereby, an electro-optical device having high display characteristics can be obtained.

In the electro-optical device , a concave portion is provided in a region sandwiched between the first electrode and the second electrode in one of the substrates, or the third electrode and the fourth electrode are planar. A convex portion may be provided in a region sandwiched between the two.
Thereby, an electro-optical device having high display characteristics can be obtained.

The electro-optical device, electrical-optical material may be contain a cholesteric blue phase.
The cholesteric blue phase is a kind of electro-optic material that exhibits optical isotropy when no electric field is applied and exhibits optical anisotropy proportional to the square of the electric field strength when an electric field is applied. In the present invention, since the electro-optical material contains a cholesteric blue phase, an equivalent light transmittance can be obtained between the reflective display region and the transmissive display region. Thereby, an electro-optical device having high display characteristics can be obtained.

The electro-optical device, the gas-optical material conductive, smectic blue phase, a cubic phase may be include any of a smectic D phase and micellar phases.
Smectic blue phase, cubic phase, smectic D phase and micelle phase are optically isotropic when no electric field is applied and exhibit optical anisotropy proportional to the square of the electric field strength when an electric field is applied It is a kind of. In the present invention, since the electro-optical material contains a smectic blue phase, an equivalent light transmittance can be obtained between the reflective display region and the transmissive display region. Thereby, an electro-optical device having high display characteristics can be obtained.

The electro-optical device may be an interface to the alignment film is provided with at least one of the electric-optical material layer of the substrate of a pair.
According to the present invention, since the alignment film is provided at the interface with at least one electro-optical material layer of the pair of substrates, the alignment of the electro-optical material can be supplementarily regulated when an electric field is applied. it can.

The electro-optical device, Oriented films may be have been rubbed in a direction orthogonal to the array direction between the first electrode and the second electrode.
According to the present invention, since the alignment film is rubbed in a direction orthogonal to the arrangement direction of the first electrode and the second electrode, the alignment of the electro-optic material can be reliably regulated when an electric field is applied. Can do.

Electronic device according to the present invention, you mounting tower the electro-optical device.
According to the present invention, since an electro-optical device capable of obtaining the same light transmittance in the transmissive display area and the reflective display area and capable of displaying with high contrast is mounted, an electronic apparatus having high display quality and high reliability. Can be obtained.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
(Configuration of liquid crystal display device)
FIG. 1 is a diagram showing an overall configuration of the liquid crystal display device 1. The present embodiment is an active matrix type transflective liquid crystal display device using a thin film transistor (hereinafter referred to as TFT) element as a switching element, and a horizontal electric field that applies an electric field (lateral electric field) in the direction of the substrate surface. Of the methods, a liquid crystal display device adopting a method called an IPS (In-Plane Switching) method will be described as an example.

  As shown in the figure, the liquid crystal display device 1 is mainly composed of a liquid crystal panel 2 and a backlight 3. The liquid crystal panel 2 and the backlight 3 are arranged so as to overlap in plan view, and only the liquid crystal panel 2 is shown in FIG. A flexible circuit board (not shown) is connected to the liquid crystal panel 2.

  In the liquid crystal panel 2, a pair of substrates, specifically, a TFT array substrate 4 and a color filter substrate 5 are bonded together by a sealing material 7, and a liquid crystal layer 6 is enclosed in a region partitioned by the sealing material 7. It has a configuration. An injection port 7 a for injecting liquid crystal is provided in a part of the sealing material 7. The injection port 7a is sealed with a sealing material 7b. A peripheral parting region (peripheral region) 8 is provided in a region inside the sealing material 7. The area inside the peripheral parting area 8 is a display area 9 for displaying images, moving images, and the like. In the display area 9, a plurality of sub-pixel areas 10 are provided in a matrix.

  In the present embodiment, three sub-pixel regions 10 adjacent in the left-right direction in the figure constitute one set to constitute one pixel. The three sub pixel areas 10 constituting one pixel are a red sub pixel area for displaying red, a green sub pixel area for displaying green, and a blue sub pixel area for displaying blue. A region between the sub-pixel regions 10 is an inter-pixel region 11.

  The peripheral edge portion of the TFT array substrate 4 is an overhanging region protruding from the color filter substrate 5. A scanning line driving circuit 12 for generating a scanning signal is formed on the left side and the right side in the drawing in the overhang region. On the lower side in the figure, a data line driving circuit 13 for generating a data signal and a connection terminal 15 for connecting to a flexible circuit board are formed. In a region between the scanning line driving circuit 12 and the connection terminal 15, a wiring 16 that connects them is formed.

FIG. 2 is a plan view showing the configuration of one sub-pixel region 10 and inter-pixel region 11 in the liquid crystal display device 1. In FIG. 2, the color filter substrate 5 is not shown for convenience of explanation.
As shown in the figure, the sub-pixel region 10 has a rectangular shape in plan view, and the vertical direction (column direction of the matrix) in the figure is the longitudinal direction and the horizontal direction (matrix row direction) in the figure is short. It is a hand direction. In the sub-pixel region 10, a light reflection layer 41, a pixel electrode 42, and a common electrode 43 are disposed. In the inter-pixel region 11, scanning lines 44, data lines 45, common electrode lines 46, semiconductor thin films 47, and columnar spacers 48 are arranged.

A configuration in the inter-pixel region 11 will be described.
The scanning line 44 is made of a metal such as aluminum, chromium, or tantalum, and is a wiring extending in the short direction (left and right direction in the drawing) of the sub-pixel region 10. One end of the scanning line 44 is connected to the scanning line driving circuit 12 (see FIG. 1), and supplies the scanning signal generated by the scanning line driving circuit 12. The scanning line 44 is disposed in the inter-pixel region 11 below the sub-pixel region 10 in the drawing.

  Similarly to the scanning line 44, the data line 45 is made of a metal such as aluminum, chromium, or tantalum and extends in the longitudinal direction (vertical direction in the drawing) of the sub-pixel region 10. One end of the data line 45 is connected to the data line driving circuit 13 (see FIG. 1) and supplies a data signal generated by the data line driving circuit 13. The data line 45 is provided with a source electrode 45 a that branches toward the semiconductor thin film 47. The source electrode 45 a is an L-shaped electrode in plan view, and is provided so as to partially overlap the semiconductor thin film 47 in plan view.

  Similar to the scanning line 44 and the data line 45, the common electrode line 46 is made of a metal such as aluminum, chromium, or tantalum, and extends in the short direction (direction in the figure) of the sub-pixel region 10. The common electrode line 46 is connected to each common electrode 43 provided in each sub-pixel region 10 and is disposed in the inter-pixel region 11 on the upper side of the sub-pixel region 10 in the drawing.

  The scanning lines 44 and the data lines 45 are provided so as to intersect within the inter-pixel region 11 and are arranged in a lattice shape in plan view. The sub-pixel area 10 is configured to be located in an area surrounded by the scanning lines 44 and the data lines 45.

  The semiconductor thin film 47 is made of, for example, amorphous silicon, and is a thin film provided in an island shape in a region overlapping the scanning line 44 in plan view. The semiconductor thin film 47 has a channel region 47a, a source region 47b, and a drain region 47c. The channel region 47 a is a region provided in the center of the semiconductor thin film 47 and faces the scanning line 44. The source region 47b is a region provided on one end side (left side in the figure) of the semiconductor thin film 47, and is electrically connected to the data line 45 via the source electrode 45a. The drain region 47 c is a region provided on the other end side (right side in the drawing) of the semiconductor thin film 47. A drain electrode 47d is provided in a region overlapping the drain region 47c in plan view. The drain electrode 47d is provided so as to partially overlap the contact portion 42b of the pixel electrode 42 in plan view. A contact hole 47e is provided in a portion where the contact portion 42b and the drain electrode 47d overlap in plan view.

  The columnar spacer 48 is a spacer member for maintaining a constant distance between the TFT array substrate 4 and the color filter substrate 5. The columnar spacer 48 is provided on the lower right corner of the sub-pixel region 10 in the inter-pixel region 11.

A configuration in the sub-pixel region 10 will be described.
The light reflecting layer 41 is made of a metal having high light reflectance such as aluminum or silver, and is a thin film provided so as to cover almost half of the sub-pixel region 10. Of the sub-pixel region 10, the region covered with the light reflecting layer 41 is the reflective display region 10a, and the region not covered with the light reflecting layer is the transmissive display region 10b. In order to improve the visibility in the reflective display, the surface of the light reflecting layer 41 may be uneven.

  The pixel electrode 42 is an electrode member including a base end portion 42a, a contact portion 42b, and a branch portion 42c. The base end part 42a, the contact part 42b, and the branch part 42c are each made of a transparent conductive material such as ITO (Indium Tin Oxide).

  The base end portion 42 a is provided on the transmissive display region 10 b side in the sub-pixel region 10, and is provided so as to extend in the short direction of the sub-pixel region 10. The width of the base end portion 42a (the dimension in the direction orthogonal to the extending direction) is, for example, about 10 μm and constant. The base end portion 42 a is disposed at a position close to the scanning line 44.

  The contact part 42b is a part protruding from the base end part 42a toward the scanning line 44, and is provided integrally with the base end part 42a. The contact part 42b is provided so that a part thereof overlaps the scanning line 44 in plan view. The contact portion 42b is electrically connected to the drain electrode 47d through the contact hole 47e.

  The branch portion 42c is a portion extending in the longitudinal direction of the sub-pixel region 10 from the base end portion 42a, and is provided integrally with the base end portion 42a. The width of the branch portion 42c (the dimension in the direction perpendicular to the extending direction) is, for example, about 10 μm and constant. The branch portion 42c extends from the transmissive display region 10b side where the base end portion 42a is provided to the reflective display region 10a side so as to straddle both regions, and the short direction of the sub-pixel region 10 For example, a plurality of them are arranged at a pitch of about 10 μm. A portion (third electrode) provided on the reflective display region 10a side of the branch portion 42c and a portion (first electrode) provided on the transmissive display region 10b side of the branch portion 42c are integrally formed. Has been. Of course, each part may be separated.

  The common electrode 43 is an electrode member including a base end portion 43a, a contact portion 43b, and a branch portion 43c. Similar to the pixel electrode 42, the base end portion 43a, the contact portion 43b, and the branch portion 43c are each made of a transparent conductive material such as ITO.

  The base end portion 43 a is provided on the reflective display region 10 a side in the sub-pixel region 10, and is provided so as to extend in the short direction of the sub-pixel region 10. The width of the base end portion 43a (the dimension in the direction orthogonal to the extending direction) is, for example, about 10 μm, and is constant and substantially the same as the width of the base end portion 42a of the pixel electrode 42. The base end portion 43 a is disposed at a position close to the common electrode line 46.

  The contact portion 43b is a portion that connects the base end portion 43a and the common electrode line 46, and is provided at a substantially central portion in the short direction of the base end portion 43a. The base end portion 43a and the common electrode line 46 are integrally provided via the contact portion 43b. The common electrode 43 in each subpixel region 10 provided in the row direction of the matrix is connected to one common electrode line 46 through a contact portion 43b.

  The branch portion 43c is a portion extending in the longitudinal direction of the sub-pixel region 10 from the base end portion 43a, and is provided integrally with the base end portion 43a. The width of the branch portion 43c (the dimension in the direction orthogonal to the extending direction) is, for example, about 10 μm, and is constant, and is substantially the same as the width of the branch portion 42c of the pixel electrode 42. The branch part 43c extends from the reflective display area 10a side where the base end part 43a is provided to the transmissive display area 10b side so as to straddle both areas. Exist. A portion (fourth electrode) provided on the reflective display region 10a side of the branch portion 43c and a portion (second electrode) provided on the transmissive display region 10b side of the branch portion 43c are integrally formed. Has been. Of course, each part may be separated. A plurality of branch portions 43 c of the common electrode 43 are arranged at a pitch of about 10 μm, for example, in the short direction of the sub-pixel region 10, and are arranged just in the middle of the adjacent branch portions 42 c of the pixel electrode 42. Thus, the branch portions 42c of the pixel electrode 42 and the branch portions 43c of the common electrode 43 are alternately arranged at equal pitches in the short direction of the sub-pixel region 10 so that the comb teeth are engaged with each other. .

  FIG. 3 is a diagram showing a configuration along the section AA in FIG. The left side in the drawing corresponds to the upper configuration in FIG. 2 (partial cross-sectional configuration of the common electrode line), and the right side in the drawing corresponds to the lower configuration in FIG. 2 (cross-sectional configuration of the scanning line). . Although not shown in FIG. 2, FIG. 3 shows a cross-sectional configuration including the color filter substrate 5.

  As shown in the figure, the TFT array substrate 4 is mainly composed of a rectangular base material 4a made of a light transmissive material such as glass, quartz, or plastic. A base layer (not shown) is formed on the base material 4a. The scanning line 44 is formed in a part of the region on the base layer. A gate insulating layer 49 is provided on the base layer. The gate insulating layer 49 is an interlayer insulating film made of an insulating material such as SiO 2 or SiN, and covers almost the entire surface of the base layer including the scanning line 44.

  On the gate insulating layer 49, the semiconductor thin film 47, the source electrode 45a, and the drain electrode 47d are formed. The semiconductor thin film 47 is disposed so as to face the scanning line 44 with the gate insulating layer 49 interposed therebetween. The semiconductor thin film 47, the gate insulating layer 49, and the scanning line 44 constitute a back gate type TFT (Thin Film Transistor). In this TFT, a region of the scanning line 44 that overlaps the semiconductor thin film 47 in plan view functions as a gate electrode.

  The source electrode 45 a is formed so as to partially cover the source region 47 b of the semiconductor thin film 47. The data line 45 (not shown in FIG. 3) is also formed in the same layer as the source electrode 45a. A resin layer 50 is provided on the gate insulating layer 49. The resin layer 50 covers almost the entire surface of the gate insulating layer 49 including the semiconductor thin film 47, the source electrode 45 a, the drain electrode 47 d, and the data line 45.

  A recess 50 b is provided in a part of the resin layer 50. The light reflecting layer 41 is provided in the recess 50b. The space between the upper surface 41a of the light reflecting layer 41 and the upper surface 50a of the resin layer 50 is flat. The upper surface 41a and the upper surface 50a constitute one substrate surface. A contact hole 47 e is provided in a region of the resin layer 50 that overlaps the drain electrode 47 d in plan view so as to penetrate the resin layer 50.

  A pixel electrode 42 and a common electrode 43 are provided on the upper surface 41a of the light reflecting layer 41 and the upper surface 50a of the resin layer 50, respectively. A contact portion 42b of the pixel electrode 42 is disposed in a region of the resin layer 50 that overlaps the contact hole 47e in plan view. The contact hole 47e is filled with a conductive material constituting the contact portion 42b, and the contact portion 42b and the portion buried in the contact hole 47e are integrated. The tip (lower side in the figure) of the portion buried in the contact hole 47e is in contact with the drain electrode 47d. In the contact portion, the contact portion 42b and the drain electrode 47d are electrically connected.

  The pixel electrode 42 and the common electrode 43 are different in height (thickness) from the substrate surface as compared with the reflective display region 10a and the transmissive display region 10b. In the reflective display region 10a, the pixel electrode 42 and the common electrode 43 are formed to a thickness of about 0.40 μm. In the transmissive display area 10b, the pixel electrode 42 and the common electrode 43 are formed to have a thickness of about 0.72 μm. Thus, the thickness of the pixel electrode 42 and the common electrode 43 in the transmissive display region 10b is larger than the thickness of the pixel electrode 42 and the common electrode 43 in the reflective display region 10a. Specifically, The thickness is about 1.8 times. In the reflective display area 10a and the transmissive display area 10b, the thicknesses of the pixel electrode 42 and the common electrode 43 can be changed.

  Comparing only in the reflective display region 10a or the transmissive display region 10b, the thickness of the pixel electrode 42 and the thickness of the common electrode 43 are substantially the same. Each part (base end part 42a, contact part 42b, branch-like part 42c) of the pixel electrode 42 and each part (base end part 43a, contact part 43b, branch-like part 43c) of the common electrode 43 are in the reflective display area 10a and Each of the transmissive display areas 10b has the same thickness.

  A phase difference plate 21 is provided on the outer surface of the substrate 4a. The phase difference plate 21 is a λ / 4 phase difference plate that imparts a phase difference of approximately ¼ wavelength to transmitted light. The retardation plate 21 has a slow axis in a predetermined direction.

  A polarizing plate 22 is provided on the outer surface of the phase difference plate 21. The polarizing plate 22 has a polarizing axis formed in a direction that forms an angle of about 45 ° with respect to the slow axis of the retardation plate 21. A circularly polarizing plate 23 is constituted by the retardation plate 21 and the polarizing plate 22. The circularly polarizing plate 23 may be a broadband circularly polarizing plate in which a polarizing plate, a λ / 2 retardation plate, and a λ / 4 retardation plate are combined in addition to a configuration in which the retardation plate 21 and the polarizing plate 22 are combined. Absent.

  On the other hand, the color filter substrate 5 is composed mainly of a rectangular base material 5a made of a light transmissive material such as glass, quartz, plastic, etc., like the TFT array substrate 4. A color filter layer 51 and a black matrix 52 are provided on the inner surface of the base material 5a (the surface facing the TFT array substrate 4).

  The color filter layer 51 is a color layer provided at a position overlapping the sub-pixel region 10 in plan view. The color filter layer 51 is composed of three color layers including a red layer, a green layer, and a blue layer made of a known material such as an organic material or an inorganic material. The red layer is provided in a region overlapping the red sub-pixel in plan view. The green layer is provided in a region overlapping the green sub-pixel in plan view. The blue layer is provided in a region overlapping with the blue sub-pixel in plan view. The black matrix 52 is provided in the inter-pixel region 11 and is made of a material such as chromium that absorbs light.

  A phase difference plate 31 is provided on the outer surface of the substrate 5a. Similar to the phase difference plate 21, the phase difference plate 31 is a λ / 4 phase difference plate that imparts a phase difference of approximately ¼ wavelength to transmitted light. The retardation plate 31 has a slow axis in a predetermined direction.

  A polarizing plate 32 is provided on the outer surface of the phase difference plate 31. The polarization axis of the polarizing plate 32 is formed in a direction that forms an angle of about 45 ° with respect to the slow axis of the retardation plate 31. A circularly polarizing plate 33 is constituted by the retardation plate 31 and the polarizing plate 32. The circularly polarizing plate 33 may be a broadband circularly polarizing plate in which a polarizing plate, a λ / 2 phase difference plate, and a λ / 4 phase difference plate are combined.

  The liquid crystal layer 6 is sandwiched so as to be in contact with both the TFT array substrate 4 and the color filter substrate 5. The liquid crystal layer 6 is made of a liquid crystal material that exhibits optical isotropy when no electric field is applied and also exhibits optical anisotropy proportional to the square of the electric field strength when the electric field is applied (Kerr effect). An example of such a liquid crystal material is a blue phase liquid crystal material. The dielectric constant of the liquid crystal molecules of the liquid crystal layer 6 is positive (ε> 0).

  The blue phase is an optically isotropic liquid crystal phase that appears in a narrow temperature range between the chiral nematic phase and the isotropic phase. The liquid crystal material of the blue phase contains, for example, a liquid crystal molecule having a narrow Kerr effect temperature range (about 1K) and a small amount of polymer (polymer-stabilized blue phase). By including a polymer together with liquid crystal molecules, the expression temperature range is about 100K.

  In the polymer-stabilized blue phase, as shown in [Equation 1], the magnitude of retardation (Δn) is proportional to the square of the electric field. In [Equation 1], K is the Kerr coefficient, λ is the wavelength of light, and E is the electric field generated between the electrodes. The Kerr coefficient of the polymer-stabilized blue phase is 3.7 × 10 −10 (mV−2), which is about 170 times that of nitrobenzene.

  The response time for the rise (expression of the Kerr effect) and the response time for the fall (disappearance of the Kerr effect) of the polymer-stabilized blue phase are both about 10 to 100 μs. A typical nematic liquid crystal has a response time of about 10 ms. The response of the polymer-stabilized blue phase is much faster than that of a general nematic liquid crystal.

  The backlight 3 has a known configuration. Specifically, a light source unit such as an LED, a light guide plate made of a transparent material such as acrylic resin, a diffusion plate provided on the liquid crystal panel 2 side with respect to the light guide plate, and a liquid crystal panel side 2 of the diffusion plate It is comprised mainly by the light-condensing plate provided in.

(Operation of liquid crystal display)
The operation of the liquid crystal display device 1 of the present embodiment will be described.
First, transmissive display (transmission mode) will be described.
Light emitted from the backlight 3 is converted into circularly polarized light in the process of passing through the polarizing plate 22 and the phase difference plate 21. The light converted into circularly polarized light passes through the TFT array substrate 4 and enters the liquid crystal layer 6. Since the blue phase is optically isotropic when no voltage is applied, the light incident on the liquid crystal layer 6 passes through the liquid crystal layer 6 as circularly polarized light without being affected by optical anisotropy. The light that has passed through the liquid crystal layer 6 passes through the color filter substrate 5 and enters the phase difference plate 31. This light is converted into linearly polarized light orthogonal to the transmission axis of the polarizing plate 32 in the process of passing through the phase difference plate 31. Since this linearly polarized light does not pass through the polarizing plate 32, black display is obtained when no voltage is applied (normally black display).

  When a voltage is applied between the pixel electrode 42 and the common electrode 43, the liquid crystal layer 6 exhibits optical anisotropy. The light emitted from the backlight 3 passes through the polarizing plate 32 and the phase difference plate 31 and is converted into circularly polarized light. This light enters the liquid crystal layer 6 and is converted into elliptically polarized light whose rotation direction is reversed in the process of passing through the liquid crystal layer 6. This light enters the phase difference plate 31, is converted into linearly polarized light substantially parallel to the transmission axis of the polarizing plate 32, and passes through the phase difference plate 31. All or part of the light transmitted through the phase difference plate 31 is transmitted through the polarizing plate 32. Thus, white display is obtained when a voltage is applied.

Next, reflection display (reflection mode) will be described.
External light incident on the outer surface of the polarizing plate 32 is converted into circularly polarized light in the process of passing through the polarizing plate 32 and the phase difference plate 31. The light converted into circularly polarized light passes through the color filter substrate 5 and enters the liquid crystal layer 6. Since the blue phase is optically isotropic when no voltage is applied, the light incident on the liquid crystal layer 6 passes through the liquid crystal layer 6 as circularly polarized light without being affected by optical anisotropy. The light transmitted through the liquid crystal layer 6 is reflected by the light reflecting layer 41, and the rotation direction is reversed at the time of reflection. The reflected light is transmitted through the liquid crystal layer 6 toward the color filter substrate 5 as circularly polarized light without being affected by optical anisotropy in a state where the rotation direction is reversed. This light passes through the color filter substrate 5 and enters the phase difference plate 31. When transmitted through the phase difference plate 31, it is converted into linearly polarized light orthogonal to the transmission axis of the polarizing plate 32. Since this linearly polarized light cannot be transmitted through the polarizing plate 32, black display is obtained when no voltage is applied (normally black display).

  When a voltage is applied between the pixel electrode 42 and the common electrode 43, the liquid crystal layer 6 exhibits optical anisotropy. External light incident on the outer surface of the polarizing plate 32 is converted into circularly polarized light in the process of passing through the polarizing plate 32 and the phase difference plate 31. The light converted into circularly polarized light passes through the color filter substrate 5 and enters the liquid crystal layer 6. This light is reflected by the light reflection layer 41 with a predetermined phase difference (λ / 4) given in the process of passing through the liquid crystal layer 6. After being reflected by the light reflection layer 41, a predetermined phase difference (λ / 4) is given again when the liquid crystal layer 6 is transmitted toward the color filter substrate 5. The light that has passed through the liquid crystal layer 6 passes through the color filter substrate 5 and enters the phase difference plate 31. In the process of passing through the phase difference plate 31, the light is converted into linearly polarized light parallel to the transmission axis of the polarizing plate 32. All or part of the light transmitted through the phase difference plate 31 is transmitted through the polarizing plate 32. Thus, white display is obtained when a voltage is applied.

  The magnitude of the retardation is defined by the product (Δnd) of the thickness (d) of the liquid crystal layer 6 and the optical anisotropy (Δn). In the so-called transflective liquid crystal display device 1 provided with the reflective display region 10a and the transmissive display region 10b, light passes through the liquid crystal layer 6 in the reflective display region 10a twice. This is equivalent to the thickness of the liquid crystal layer 6 in the reflective display region 10a being twice the thickness of the liquid crystal layer 6 in the transmissive display region 10b. Therefore, in a configuration that does not employ a multi-gap, the retardation of the reflective display region 10a is twice that of the transmissive display region 10b. On the other hand, by increasing the retardation of the transmissive display region 10b, the retardation of the transmissive display region 10b can be made equal to the retardation of the reflective display region 10a.

  According to the present embodiment, the transmissive display area 10b is higher in height from the substrate surface of the pixel electrode 42 and the common electrode 43 than the reflective display area 10a, and thus is sandwiched between the pixel electrode 42 and the common electrode 43 accordingly. The range of the electric field applied to the liquid crystal layer 6 in the part can be widened. Therefore, a stronger electric field can be applied to the portion of the liquid crystal layer 6 sandwiched between the pixel electrode 42 and the common electrode 43 in the transmissive display region 10b.

  As described above, according to the present embodiment, the optical anisotropy of the liquid crystal layer 6 increases in proportion to the square of the electric field, so that the liquid crystal layer 6 in the transmissive display region 10b has a greater effect than the liquid crystal layer 6 in the reflective display region 10a. By applying a stronger electric field, the optical anisotropy of the transmissive display region 10b becomes larger than the optical anisotropy of the reflective display region 10a. For this reason, the retardation of the transmissive display area 10b can be increased. By increasing the retardation of the transmissive display area 10b, the retardation of the transmissive display area 10b can be made equal to the retardation of the reflective display area, and the difference in light transmittance between the reflective display area 10a and the transmissive display area 10b. Can be eliminated. Thereby, the difference in contrast between the reflective display region 10a and the transmissive display region 10b can be eliminated, and the liquid crystal display device 1 having high display characteristics can be obtained.

  FIG. 4 shows the magnitude (V) of the voltage applied between the pixel electrode 42 and the common electrode 43 and the magnitude of the light transmittance (relative value) of the liquid crystal layer 6 in the liquid crystal display device 1 of the present embodiment. It is a graph which shows the relationship. The vertical axis of the graph indicates the light transmittance. The horizontal axis of the graph indicates the voltage magnitude. In the graph, the light transmittance of the liquid crystal layer 6 in the reflective display region 10a is indicated by a solid line, and the light transmittance of the liquid crystal layer 6 in the transmissive display region 10b is indicated by a broken line.

  As shown in the figure, the value of the light transmittance of the reflective display region 10a and the light transmittance of the transmissive display region 10b in the range where the magnitude of the voltage applied between the pixel electrode 42 and the common electrode 43 exceeds 6V. Is close to the value of. When the magnitude of the voltage is in the range of 8V to 12V, the light transmittance values in both regions are very close. In particular, when the voltage value is in the range of 9V to 10V, the light transmittance values of both regions are substantially the same.

  The voltage values described above are such that the pixel electrode 42 and the common electrode 43 are formed to have a thickness of about 0.40 μm in the reflective display region 10a, and the pixel electrode 42 and the common electrode 43 have a thickness of about 0.40 μm in the transmissive display region 10b. It is a value when formed to about 72 μm. In the reflective display area 10a and the transmissive display area 10b, the thicknesses of the pixel electrode 42 and the common electrode 43 can be changed. The voltage value can be changed by changing the thickness of the pixel electrode 42 and the common electrode 43. In the present embodiment, the thicknesses of the pixel electrode 42 and the common electrode 43 are adjusted so that the retardation (Δnd) of the reflective display region 10a is λ / 4 and the retardation of the transmissive display region 10b is λ / 2.

  In the configuration of the liquid crystal display device 1 of the present embodiment, when an equal voltage is applied between the pixel electrode 42 and the common electrode 43, the light transmittance of the reflective display region 10a and the light transmittance of the transmissive display region 10b are as follows. A range of voltages appears to be equivalent. Therefore, when the liquid crystal display device 1 is driven, by applying a voltage within a range in which the light transmittances in both regions are equal, the light transmittances in both regions can be equalized, and the same in both regions. Contrast can be obtained.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.
FIG. 5 is a cross-sectional view showing the configuration of the liquid crystal display device 101 according to the present embodiment. This figure corresponds to FIG. 3 in the first embodiment. In the liquid crystal display device 101 of this embodiment, the configuration of the color filter substrate and the liquid crystal layer is the same as that of the first embodiment, and the configuration of the TFT array substrate is different from that of the first embodiment.

  As shown in FIG. 5, the pixel electrode 142 and the common electrode 143 are provided on the TFT array substrate 104 side. In the reflective display region 110 a, the pixel electrode (third electrode) 142 and the common electrode (fourth electrode) 143 are directly provided on the surface 141 a of the light reflecting layer 141. In the transmissive display region 110b, an insulating layer 155 is provided on the surface 150a of the resin layer 150, and a pixel electrode (first electrode) 142 and a common electrode (second electrode) 143 are provided on the insulating layer 155. Yes. The pixel electrode 142 and the common electrode 143 on the reflective display region 110a side, and the pixel electrode 142 and the common electrode 143 on the transmissive display region 110b side are integrally formed. Of course, the pixel electrode 142 and the common electrode 143 may be separated for each region.

  The thickness of the pixel electrode 142 and the common electrode 143 in the reflective display region 110a and the thickness of the pixel electrode 142 and the common electrode 143 in the transmissive display region 110b are both about 0.4 μm. The pitch of the arrangement of the pixel electrode 142 and the common electrode 143 is about 8 μm, and the width of each electrode is about 8 μm.

  The insulating layer 155 is made of an electrically insulating material, for example, an inorganic material such as SiO 2 or SiN, or an organic material such as resin. The thickness of the insulating layer 155 is about 2 μm. In the transmissive display region 110b, the pixel electrode 142 and the common electrode 143 are provided on the color filter substrate 105 side (position where the height from the substrate surface (surface 150a of the resin layer 150) is higher) by the thickness of the insulating layer 155. It has been.

The layer thickness of the liquid crystal layer 106 is constant. The thickness of the portion sandwiched between the pixel electrode 142 and the common electrode 143 in the liquid crystal layer 106 is equal. A distance t1 from the central portion M in the thickness direction of the portion to the pixel electrode 142 and the common electrode 143 in the reflective display region 110a is from the central portion M to the pixel electrode 142 and the common electrode 143 in the transmissive display region 110b. It is larger than the distance t2 (t1> t2).
Other configurations are the same as those of the liquid crystal display device 1 according to the first embodiment.

  Thus, in this embodiment, since the pixel electrode 142 and the common electrode 143 are provided on the color filter substrate 105 side in the transmissive display region 110b as compared with the reflective display region 110a, the transmissive display region 110b is more in the direction. The distance in the thickness direction from the pixel electrode 142 and the common electrode 143 to the central portion M of the liquid crystal layer 106 becomes smaller (t1> t2), and the pixel electrode 142 and the common electrode 143 are closer to the central portion of the liquid crystal layer 106. Will be placed. Therefore, an electric field can be applied to the portion of the liquid crystal layer 106 sandwiched between the pixel electrode 142 and the common electrode 143 over a wide range in the vertical direction of the electrodes 142 and 143. Therefore, a stronger electric field is applied to the liquid crystal layer 106 in the transmissive display region 110b than in the liquid crystal layer 106 in the reflective display region 110a. The retardation of the transmissive display area 110b can be made equal to the retardation of the reflective display area 110a, and the difference in light transmittance between the reflective display area 110a and the transmissive display area 110b can be eliminated. Thereby, the difference in contrast between the reflective display region 110a and the transmissive display region 110b can be eliminated, and the liquid crystal display device 101 having high display characteristics can be obtained.

  6 shows the magnitude (V) of the voltage applied between the pixel electrode 142 and the common electrode 143 and the magnitude of the light transmittance (relative value) of the liquid crystal layer 106 in the liquid crystal display device 101 of the present embodiment. It is a graph which shows the relationship. The vertical axis of the graph indicates the light transmittance. The horizontal axis of the graph indicates the voltage magnitude. In the graph, the light transmittance of the liquid crystal layer 106 in the reflective display region 110a is indicated by a solid line, and the light transmittance of the liquid crystal layer 106 in the transmissive display region 110b is indicated by a broken line.

  As shown in the figure, the value of the light transmittance of the reflective display region 110a and the light transmittance of the transmissive display region 110b in the range where the magnitude of the voltage applied between the pixel electrode 142 and the common electrode 43 exceeds 6V. Is close to the value of. When the voltage magnitude is in the range of 7V to 12V, the light transmittance values in both regions are very close. In particular, when the voltage value is in the range of 8V to 10V, the light transmittance values of both regions are almost the same.

  In the reflective display area 110a, the pixel electrode 142 and the common electrode 143 are formed with a thickness of about 0.40 μm, and the insulating layer 155 of the transmissive display area 110b is formed with a thickness of about 2 μm. It is a value when there is. The thickness of the pixel electrode 42 and the common electrode 43 in the reflective display region 110a and the transmissive display region 110b, the thickness of the insulating layer 155 in the transmissive display region 110b, and the like can be changed. The voltage value can be changed by changing these values. In the present embodiment, the thicknesses of the pixel electrode 142 and the common electrode 143 are adjusted so that the retardation (Δnd) of the reflective display region 110a is λ / 4 and the retardation of the transmissive display region 110b is λ / 2.

  In the configuration of the liquid crystal display device 101 of this embodiment, when an equal voltage is applied between the pixel electrode 142 and the common electrode 143, the light transmittance of the reflective display region 110a and the light transmittance of the transmissive display region 110b are as follows. A range of voltages appears to be equivalent. Therefore, when driving the liquid crystal display device 101, by applying a voltage within a range in which the light transmittances in both regions are equal, the light transmittances in both regions can be equalized, and the same in both regions. Contrast can be obtained.

[Third Embodiment]
Next, a third embodiment of the present invention will be described.
FIG. 7 is a cross-sectional view showing the configuration of the liquid crystal display device 201 according to this embodiment. This figure corresponds to FIG. 3 in the first embodiment. In the liquid crystal display device 201 of this embodiment, the configuration of the color filter substrate and the liquid crystal layer is the same as that of the first embodiment, and the configuration of the TFT array substrate is different from that of the first embodiment.

  As shown in FIG. 7, the pixel electrode 242 and the common electrode 243 are provided on the TFT array substrate 204 side. In the reflective display area 210 a, a pixel electrode (third electrode) 242 and a common electrode (fourth electrode) 243 are provided on the surface 241 a of the light reflecting layer 241. In the transmissive display area 210 b, the pixel electrode (first electrode) 242 and the common electrode (second electrode) 243 are provided on the surface 250 a of the resin layer 250. The pixel electrode 242 and the common electrode 243 on the reflective display region 210a side, and the pixel electrode 242 and the common electrode 243 on the transmissive display region 210b side are integrally formed. Of course, the pixel electrode 242 and the common electrode 243 may be separated for each region.

  The thicknesses of the pixel electrode 242 and the common electrode 243 in the reflective display area 210a and the thicknesses of the pixel electrode 242 and the common electrode 243 in the transmissive display area 210b are both about 0.4 μm. The pitch of the arrangement of the pixel electrodes 242 and the common electrode 243 is about 8 μm, and the width of each electrode is about 8 μm.

  In the transmissive display area 210b, a recess 255 is provided in an area between the pixel electrode 242 and the common electrode 243 in the resin layer 250. The recess 255 has the same width as the distance between the pixel electrode 242 and the common electrode 243, and the depth (distance from the surface 250 a to the bottom of the resin layer 250) is approximately 2 in the entire recess 255. .5 μm and uniform. In the reflective display area 210 a, the surface 241 a of the light reflecting layer 241 is an interface with the liquid crystal layer 206. In the transmissive display area 210 b, the bottom of the recess 255 is an interface with the liquid crystal layer 206. Accordingly, the thickness of the liquid crystal layer 206 in the portion sandwiched between the pixel electrode 242 and the common electrode 243 is larger in the transmissive display region 210b than in the reflective display region 210a.

In FIG. 7, in the liquid crystal layer 206 of the reflective display region 210a, the central portion in the thickness direction of the portion sandwiched between the pixel electrode 242 and the common electrode 243 (reflective side central portion) is denoted by Mr, and the transmissive display region 210b The center part (transmission side center part) is indicated by Mt. The reflection side central portion Mr is located closer to the color filter substrate 205 than the transmission side central portion Mt. Therefore, the distance t3 from the reflection side central portion Mr to the pixel electrode 242 and the common electrode 243 in the reflection display region 210a is the distance t4 from the transmission side central portion Mt to the pixel electrode 242 and the common electrode 243 in the transmission display region 210b. (T3> t4).
Other configurations are the same as those of the liquid crystal display device 1 according to the first embodiment.

  Thus, in this embodiment, since the recessed part 255 is provided in the area | region between the pixel electrode 242 and the common electrode 243 among the resin layers 250, the pixel in the reflective display area 210a from the reflection side center part Mr. The distance t3 between the electrode 242 and the common electrode 243 is larger than the distance t4 from the transmissive side center portion Mt to the pixel electrode 242 and the common electrode 243 in the transmissive display area 210b (t3> t4). The pixel electrode 242 and the common electrode 243 are disposed at a position closer to the central portion (transmission-side central portion Mt). Therefore, an electric field can be applied to a portion of the liquid crystal layer 206 sandwiched between the pixel electrode 242 and the common electrode 243 over a wide range in the vertical direction of the electrodes 242 and 243. Therefore, a stronger electric field is applied to the liquid crystal layer 206 in the transmissive display area 210b than in the liquid crystal layer 206 in the reflective display area 210a. Since the retardation of the transmissive display area 210b can be made equal to the retardation of the reflective display area 210a, the difference in light transmittance between the reflective display area 210a and the transmissive display area 210b can be eliminated. Thereby, the difference in contrast between the reflective display area 210a and the transmissive display area 210b can be eliminated, and the liquid crystal display device 201 having high display characteristics can be obtained.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described.
FIG. 8 is a cross-sectional view showing the configuration of the liquid crystal display device 301 according to this embodiment. FIG. 3 shows a simplified view of FIG. 3 in the first embodiment. In the liquid crystal display device 301 of this embodiment, the configuration of the color filter substrate and the liquid crystal layer is the same as that of the first embodiment, and the configuration of the TFT array substrate is different from that of the first embodiment.

  As shown in FIG. 8, the pixel electrode 342 and the common electrode 343 are provided on the TFT array substrate 304 side. In the reflective display area 310 a, a pixel electrode (third electrode) 342 and a common electrode (fourth electrode) 343 are provided on the surface 341 a of the light reflecting layer 341. In the transmissive display region 310b, a pixel electrode (first electrode) 342 and a common electrode (second electrode) 343 are provided on the surface 350a of the resin layer 350. The pixel electrode 342 and the common electrode 343 on the reflective display region 310a side, and the pixel electrode 342 and the common electrode 343 on the transmissive display region 310b side are integrally formed. Of course, the pixel electrode 342 and the common electrode 343 may be separated for each region.

  The thickness of the pixel electrode 342 and the common electrode 343 in the reflective display area 310a and the thickness of the pixel electrode 342 and the common electrode 343 in the transmissive display area 310b are both about 0.4 μm. The pitch of the arrangement of the pixel electrodes 342 and the common electrode 343 is about 8 μm, and the width of each electrode is about 8 μm.

  In the reflective display region 310a, a convex portion 355 is provided in a region sandwiched between the pixel electrode 342 and the common electrode 343 on the surface 341a of the light reflecting layer 341. The convex portion 355 is provided so as to partially fill the space between the pixel electrode 342 and the common electrode 343. In the reflective display region 310 a, the surface of the convex portion 355 is an interface with the liquid crystal layer 306. In the transmissive display region 310 b, the surface 350 a of the resin layer 350 is an interface with the liquid crystal layer 306. Accordingly, in the transmissive display region 310b, the thickness of the liquid crystal layer 306 in the portion sandwiched between the pixel electrode 342 and the common electrode 343 is larger than that in the reflective display region 310a.

In FIG. 8, the central portion in the thickness direction (reflective side central portion) of the portion sandwiched between the pixel electrode 342 and the common electrode 343 in the liquid crystal layer 306 of the reflective display region 310a is denoted by Mr, and the transmissive display region 310b The center part (transmission side center part) is indicated by Mt. The reflection-side center portion Mr is located closer to the color filter substrate 305 than the transmission-side center portion Mt. Therefore, the distance t5 from the reflection-side center portion Mr to the pixel electrode 342 and the common electrode 343 in the reflection display region 310a is the distance t6 from the transmission-side center portion Mt to the pixel electrode 342 and the common electrode 343 in the transmission display region 310b. (T5> t6).
Other configurations are the same as those of the liquid crystal display device 1 according to the first embodiment.

  As described above, in the present embodiment, the convex portion 355 is provided in a region sandwiched between the pixel electrode 342 and the common electrode 343 on the surface 341a of the light reflection layer 341 in the reflective display region 310a. A distance t5 from the central portion Mr to the pixel electrode 342 and the common electrode 343 in the reflective display region 310a is larger than a distance t6 from the transmission side central portion Mt to the pixel electrode 342 and the common electrode 343 in the transmissive display region 310b. (T5> t6), the pixel electrode 342 and the common electrode 343 are disposed at a position closer to the central portion (transmission-side central portion Mt) in the transmissive display region 310b. Thereby, similarly to the above-described embodiment, the difference in contrast between the reflective display area 310a and the transmissive display area 310b can be eliminated, and the liquid crystal display device 301 having high display characteristics can be obtained.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described.
FIG. 9 is a cross-sectional view showing the configuration of the liquid crystal display device 401 according to this embodiment. FIG. 3 shows a simplified view of FIG. 3 in the first embodiment. In the liquid crystal display device 401 of this embodiment, the configuration of the color filter substrate is the same as that of the first embodiment, and the configuration of the TFT array substrate is different from that of the first embodiment. This embodiment is different from the first embodiment in that the dielectric constant of the liquid crystal molecules of the liquid crystal layer 406 is negative (ε <0).

  As shown in FIG. 9, the pixel electrode 442 and the common electrode 443 are provided on the TFT array substrate 404 side. In the reflective display area 410a, a pixel electrode (third electrode) 442 and a common electrode (fourth electrode) 443 are provided on the surface 441a of the light reflecting layer 441. In the transmissive display region 410b, a pixel electrode (first electrode) 442 and a common electrode (second electrode) 443 are provided on the surface 450a of the resin layer 450. The pixel electrode 442 and the common electrode 443 on the reflective display area 410a side and the pixel electrode 442 and the common electrode 443 on the transmissive display area 410b side are integrally formed. Needless to say, the pixel electrode 442 and the common electrode 443 may be separated for each region.

  In the reflective display region 410a, the thickness of the pixel electrode 442 and the thickness of the common electrode 443 are different. Specifically, the common electrode 443 is thicker than the pixel electrode 442. Even in the transmissive display region 310b, the thickness of the pixel electrode 442 is different from the thickness of the common electrode 443, and the common electrode 443 is thicker than the pixel electrode 442. The pitch of the arrangement of the pixel electrodes 342 and the common electrode 343 is about 8 μm, and the width of each electrode is about 8 μm.

  As described above, according to the present embodiment, in the portion where the liquid crystal layer 406 exhibits negative dielectric anisotropy (ε <0) with respect to the electric field, the dimension of the pixel electrode 442 in the thickness direction is the same as that of the common electrode 443. Since it is smaller than the dimension in the thickness direction, the alignment of the liquid crystal molecules in the portion exhibiting negative dielectric anisotropy can be regulated in a desired direction.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described.
FIG. 10 is a cross-sectional view showing the configuration of the liquid crystal display device 501 according to this embodiment. In the liquid crystal display device 501 of this embodiment, the configuration of the color filter substrate is the same as that of the first embodiment, and the configuration of the TFT array substrate is different from that of the first embodiment.

  As shown in FIG. 10, the pixel electrode 542 and the common electrode 543 are provided on the TFT array substrate 504 side. The pixel electrode 542 and the common electrode 543 include a red sub-pixel 510R provided with a red color filter layer 551R, a green sub-pixel 510G provided with a green color filter layer 551G, and a blue color provided with a blue color filter layer 551B. The height (thickness) from the substrate surface 550a is different between the sub-pixels 510B. Specifically, when the height in the red sub-pixel 510R is t7, the height in the green sub-pixel 510G is t6, and the height in the blue sub-pixel 510B is t9, t7> t8> t9. The heights of the pixel electrode 542 and the common electrode 543 are reduced in the order of the red sub-pixel 510R, the green sub-pixel 510G, and the blue sub-pixel 510B.

  As described above, according to the present embodiment, the height of the pixel electrode 542 and the common electrode 543 is reduced in the order of the red sub-pixel 510R, the green sub-pixel 510G, and the blue sub-pixel 510B. Optimal light transmittance can be obtained. Thereby, the liquid crystal display device 501 with high display characteristics can be obtained.

[Seventh Embodiment]
Next, a seventh embodiment of the present invention will be described.
FIG. 6 is a perspective view showing the overall configuration of the electronic apparatus (mobile phone) according to the present embodiment.
The mobile phone 600 includes a housing 601, an operation unit 602 provided with a plurality of operation buttons, and a display unit 603 that displays images, moving images, characters, and the like. The display unit 603 includes the liquid crystal display devices 1 to 501 according to the present embodiment.
As described above, since the liquid crystal display devices 1 to 501 capable of obtaining the same light transmittance in the transmissive display region and the reflective display region and capable of high-contrast display are mounted, the display quality is high and the mobile phone is highly reliable. A phone 600 can be obtained.

The technical scope of the present invention is not limited to the above-described embodiment, and appropriate modifications can be made without departing from the spirit of the present invention.
In the above embodiment, the configuration of the liquid crystal layer has been described as a configuration including a cholesteric blue phase, but the configuration is not limited thereto. For example, it may be configured to include materials such as a smectic blue phase, a cubic phase, a smectic D phase, and a micelle phase.

  In the above embodiment, the configuration in which the alignment film is not provided has been described. However, for example, the alignment film may be formed at the interface with the liquid crystal layer of the TFT array substrate. In this case, it is preferable to perform a rubbing process in a direction in which the orientation of liquid crystal molecules changes due to an electric field. Thereby, the change in the alignment of the liquid crystal molecules can be promoted.

  The configuration of the pixel electrode and the common electrode and the configuration of the periphery thereof are not limited to the configurations described in the above embodiments. The range in the thickness direction of the electric field applied to the portion of the electro-optic material layer sandwiched between the pixel electrode and the common electrode in the transmissive display region is equal to the electrical portion of the portion sandwiched between the pixel electrode and the common electrode in the reflective display region. Any other configuration may be used as long as it is larger than the range of the electric field applied to the optical material layer in the thickness direction.

1 is a plan view showing a configuration of a liquid crystal display device according to a first embodiment of the present invention. FIG. 3 is a plan view illustrating a configuration of a sub-pixel region of the liquid crystal display device according to the embodiment. FIG. 3 is a cross-sectional view illustrating a configuration of a liquid crystal display device according to the embodiment. The graph which shows the relationship between the voltage applied between a pixel electrode and a common electrode, and light transmittance. Sectional drawing which shows the structure of the liquid crystal display device which concerns on 2nd Embodiment of this invention. The graph which shows the relationship between the voltage applied between a pixel electrode and a common electrode, and light transmittance. Sectional drawing which shows the structure of the liquid crystal display device which concerns on 3rd Embodiment of this invention. Sectional drawing which shows the structure of the liquid crystal display device which concerns on 4th Embodiment of this invention. Sectional drawing which shows the structure of the liquid crystal display device which concerns on 5th Embodiment of this invention. Sectional drawing which shows the structure of the liquid crystal display device which concerns on 6th Embodiment of this invention. The perspective view which shows the structure of the mobile telephone which concerns on 7th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1-501 ... Liquid crystal display device 2 ... Liquid crystal panel 4 ... TFT array substrate 5 ... Color filter substrate 6 ... Liquid crystal layer 10 ... Sub pixel area 10a ... Reflection display area 10b ... Transmission display area 11 ... Inter-pixel area 21, 31 ... Phase difference plate 22, 32 ... Polarizing plate 23, 33 ... Circular polarizing plate 41 ... Light reflecting layer 42 ... Pixel electrode 42a ... Base end portion 42b ... Contact portion 42c ... Branched portion 43 ... Common electrode 43a ... Base end portion 43b ... Contact Part 43c ... Branch part 50 ... Resin layer 50b ... Concave part 155 ... Insulating layer 255 ... Concave part 355 ... Convex part 600 ... Cellular phone 603 ... Display part

Claims (9)

  1. An electro-optical device comprising a plurality of sub-pixel regions each having a reflective display region for performing reflective display and a transmissive display region for performing transmissive display, with an electro-optical material layer sandwiched between a pair of substrates.
      The electro-optic material forming the electro-optic material layer is optically isotropic when no electric field is applied, and exhibits optical anisotropy proportional to the square of the electric field strength when an electric field is applied, and has a negative dielectric property. Has anisotropy
    In the transmissive display area, a first electrode and a height from the one substrate higher than that of the first electrode are formed on the electro-optic material layer side of one of the pair of substrates. Two electrodes,
    The reflective display region includes a third electrode on the electro-optic material layer side of the one substrate, and a fourth electrode formed with a height higher than the third electrode from the one substrate. Provided,
    The first electrode and the second electrode, and the third electrode and the fourth electrode have a thickness of the electro-optic material layer sandwiched between the first electrode and the second electrode in the transmissive display region. The reflective display region is formed to be thicker than the thickness of the electro-optic material layer sandwiched between the third electrode and the fourth electrode.
      Electro-optic device.
  2. The plurality of sub-pixel regions include a first sub-pixel region that displays first color light, and a second sub-pixel region that displays second color light,
    The height of the first electrode and the second electrode from the surface of the one substrate in the first sub-pixel region is such that the first electrode and the height from the surface of the one substrate in the second sub-pixel region are Formed higher than the height of the second electrode;
    The electro-optical device according to claim 1.
  3. The plurality of sub-pixel regions include a first sub-pixel region that displays first color light, and a second sub-pixel region that displays second color light,
      The heights of the third electrode and the fourth electrode from the surface of the one substrate in the first subpixel region are such that the third electrode from the surface of the one substrate in the second subpixel region Formed higher than the height of the fourth electrode;
    The electro-optical device according to claim 1.
  4. A recess is provided in a region of the one substrate that is planarly sandwiched between the first electrode and the second electrode, or is planarly sandwiched between the third electrode and the fourth electrode. Protrusions are provided in the area
    The electro-optical device according to claim 1.
  5. The electro-optic material includes a cholesteric blue phase;
    The electro-optical device according to claim 1 .
  6. The electro-optical material includes any one of a smectic blue phase, a cubic phase, a smectic D phase, and a micelle phase;
    The electro-optical device according to claim 1.
  7. An alignment film is provided at an interface with at least one of the electro-optic material layers of the pair of substrates.
    The electro-optical device according to claim 1.
  8. The alignment film is rubbed in a direction perpendicular to the arrangement direction of the first electrode and the second electrode;
    The electro-optical device according to claim 7.
  9. An electronic apparatus equipped with the electro-optical device according to claim 1.
JP2007078304A 2007-03-26 2007-03-26 Electro-optical device and electronic apparatus Active JP5110927B2 (en)

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