JP5154181B2 - Liquid crystal display device and electronic device - Google Patents

Description

The present invention relates to a liquid crystal display device and an electronic device including the liquid crystal display device, and more particularly to a liquid crystal display device capable of displaying predetermined characters, logos, and the like in a power-off state, and an electronic device including the liquid crystal display device. .

As a liquid crystal display device, a transflective liquid crystal display device having both transmissive and reflective properties has been developed (see Patent Document 1 below). This transflective liquid crystal display device has a light transmissive region provided with a pixel electrode and a light reflective region provided with both a pixel electrode and a reflector in one pixel region. In a dark place, the backlight is turned on and an image is displayed using the light transmission area, and in a bright place, the image is displayed using outside light in the light reflection area without turning on the backlight. It is. Therefore, the transflective liquid crystal display device
Since it is not necessary to always turn on the backlight, there is an advantage that power consumption can be greatly reduced. This transflective liquid crystal display device is widely used as a display portion of a particularly small and medium electronic device such as a mobile phone.

On the other hand, in recent years, there has been a great demand for improvements in the design of electronic devices. For example, in mobile phones, not only displays an arbitrary image on a standby screen, but also a wide variety such as a manufacturer's logo and a specific pattern. An image is displayed.
Japanese Patent Laid-Open No. 11-101992

When an image is displayed on the display unit of the liquid crystal display device, the liquid crystal display device needs to be driven and displayed while the power is on. However, in the conventional liquid crystal display device, nothing is displayed when the power is turned off, so that an image cannot be displayed when the power is turned off. Therefore, in order to display a standby screen or the like for a long time, it is necessary to continue driving a specific pixel for a long time, so that power consumption increases accordingly. In this way, when a standby screen or the like is displayed for a long time, a transflective liquid crystal display device may be driven as a reflective type without turning on the backlight. However, the longer the display time is, the more proportional it is. As a result, power consumption increases. Such an increase in power consumption becomes a serious problem for small electronic devices such as mobile phones.

In recent years, proposals have been made to make it possible to display such an image even when the power is turned off and to improve the design of the entire device including the display unit. For this purpose, it is necessary to be able to display some image even when the power of the liquid crystal display device is turned off. However, conventionally, a liquid crystal display device that can display a substantially normal image when the power is turned on and can display any image when the power is turned off has not been known.

In view of the circumstances as described above, an object of the present invention is to provide a display with a wide range of expressive power that can display a predetermined pattern including a symbol for identification such as a company name even when the power is turned off. It is an object to provide a liquid crystal display device having high characteristics and an electronic apparatus including the liquid crystal display device.

To achieve the above object, a liquid crystal display device according to the present invention, a liquid crystal display device of a normally black mode in which the sub-picture element is provided with a display area arranged in a matrix having a light reflecting region and a light transmissive region The sub-pixel is provided at the interface between the liquid crystal layer sandwiched between the first substrate and the second substrate facing each other, the liquid crystal layer of the first substrate, and the interface of the liquid crystal layer of the second substrate. An alignment film, and a projection formed below or on the surface of the alignment film in the light reflection area when the subpixel corresponds to a pattern to be displayed in the display area when the liquid crystal display device is not driven. When the liquid crystal display device is driven, an arbitrary image is displayed on the display region by light emitted from the backlight through the light transmission region, and when the liquid crystal display device is not driven, the image is emitted through the light reflection region. By reflected light of outside light Pattern is displayed on the display region.

In the normally black mode liquid crystal display device, the liquid crystal molecules are aligned in the direction regulated by the alignment film in a non-driving state in which no electric field is applied between the liquid crystal driving electrodes,
Since it does not transmit light, the display is black. However, in a driving state in which an electric field is applied between the liquid crystal driving electrodes, the liquid crystal molecules are moved by the electric field, so that light is transmitted. However, if the structure for disturbing the orientation of the liquid crystal molecules is formed in the light reflection region of the sub-pixel, the orientation of the liquid crystal molecules is disturbed in this portion, so that an electric field is not applied between the liquid crystal driving electrodes. Light is transmitted to some extent even in the driving state.

Accordingly, the liquid crystal display device of the present invention is a normally black mode liquid crystal display device, in which the configuration for disturbing the alignment of liquid crystal molecules is formed in the light reflection region, and thus the light reflection in which the configuration for disturbing the alignment is formed. Even if the region is not driven, light leakage occurs. Therefore, even when the liquid crystal display device is in a non-driven state, when incident light from outside light is emitted, it is emitted as emitted light having a color layer color corresponding to a pattern such as an identification pattern. It is possible to display a pattern such as an identification pattern. In addition, when the liquid crystal display device is in a driving state, a good image display can be performed using the light transmission region. Accordingly, the liquid crystal display device of the present invention is a liquid crystal display device having a wide range of expressive power and high display characteristics.

Further, protrusions are formed on the surface of the alignment film Runode, the liquid crystal molecules in the vicinity of the projection in the non-driving state is oriented in random directions, but the specific direction the liquid crystal molecules in a position away from the projection is restricted by the alignment layer Oriented . What slave, the alignment direction of liquid crystal molecules of the collision force vicinity is different from the orientation direction of the liquid crystal molecules in a position away from the projection. Therefore, by forming the protrusions below or on the surface of the alignment film in the light reflection region, light leakage can be caused in the light reflection region where the protrusions are formed. It should be noted that this projection has the same effect regardless of which side of the pair of substrates constituting the liquid crystal display device is formed. In addition, it is preferable to form a plurality of protrusions in the light reflection region of the same sub-pixel because light leakage increases.

The liquid crystal display equipment according to the present invention preferably shall be driven in a vertical alignment VA (Vertically Aligned) mode or transverse electric field mode.

The liquid crystal display device driven in these VA mode or lateral electric field mode is not only a normally black mode liquid crystal display device, but also has a characteristic that the contrast is good with a wide viewing angle. A liquid crystal display device having a wide viewing angle and good contrast while exhibiting the effects of the present invention is obtained. As the liquid crystal display device driven in the lateral electric field mode, an IPS (In-Plane Switching) mode or FFS (Fringe Field Switching) mode can be used.

Furthermore, in order to achieve the above object, an electronic apparatus according to the present invention, obtain Bei the liquid crystal display device according to any one of the above.

According to the electronic apparatus of the present invention , an electronic apparatus having a normally black mode liquid crystal display device having a wide range of expressive power and good contrast can be obtained.

Hereinafter, the best embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a VA mode liquid crystal display device as a liquid crystal display device for embodying the technical idea of the present invention, and the present invention is specified as the VA mode liquid crystal display device. And is equally applicable to other embodiments within the scope of the claims. In each drawing used for explanation in this specification,
In order to make each layer and each member recognizable on the drawing, the scale is different for each layer and each member, and they are not necessarily displayed in proportion to the actual dimensions.

FIG. 1 is a diagram showing the overall configuration of the liquid crystal display device. FIG. 2 is a schematic cross-sectional view taken along the line II-II in FIG. FIG. 3 is a schematic cross-sectional view of one subpixel at a position corresponding to a pattern to be displayed according to the first embodiment. FIG. 4 is a plan view showing a display state when the liquid crystal display device of the first embodiment is not driven. FIG. 5 is a schematic cross-sectional view of one sub pixel at a position corresponding to a pattern to be displayed according to the second embodiment. 6A is a diagram showing a personal computer equipped with the liquid crystal display device of the present invention, and FIG. 6B is a diagram showing a mobile phone equipped with the liquid crystal display device of the present invention.

First, as a switching element common to the first and second embodiments, a thin film transistor (Th
In film transistor: Hereinafter, an active matrix type VA mode transflective liquid crystal display device using an element will be described as an example. As shown in FIG. 1, 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.

The liquid crystal panel 2 is a so-called transflective liquid crystal panel. In this liquid crystal panel 2, a TFT array substrate (first substrate) 4 and a color filter substrate (second substrate) 5 are bonded together by a sealing material 7, and a liquid crystal layer 6 is formed in a region partitioned by the sealing material 7. Is enclosed. An injection port 7a for injecting liquid crystal into a part of the sealing material 7
The inlet 7a is sealed with a sealing material 7b. A light shielding film (peripheral parting) 8 made of a light shielding material is provided in a region inside the sealing material 7. An area inside the peripheral parting 8 is a display area 9 for displaying an image, a moving image, or the like. The display area 9 is provided with a plurality of sub-pixels 10 in a matrix. A region between the plurality of sub-pixels 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 upper side of FIG. 1, a wiring 14 that connects the left and right scanning line driving circuits 12 is routed. A data line driving circuit 13 for generating a data signal and a connection terminal 15 for connecting to an external circuit or the like are formed on the lower side of the center of FIG. In a region between the scanning line driving circuit 12 and a connection terminal for connecting to an external circuit or the like, a wiring 16 for connecting the two is formed. In addition, an inter-substrate conductive material 17 for electrical connection between the TFT array substrate 4 and the color filter substrate 5 is provided at each corner of the color filter substrate 5.

As shown in FIG. 2, the TFT array substrate 4 includes a base material 4a formed of a material having high translucency such as glass and quartz, and a pixel electrode 48 formed on the liquid crystal side of the base material 4a. The switching element 47 for supplying an electric signal to the pixel electrode 48, the light reflection layer 45, the pixel electrode 48, the switching element 47, an alignment film 46 formed so as to cover the light reflection layer 45, and the substrate 4a The polarizing plate 49 affixed to the outer side (the side opposite to the liquid crystal layer 6) is mainly used. An interlayer film may be formed between the base material 4a and the pixel electrode 48.

The pixel electrode 48 is disposed in a region overlapping the subpixel 10 in plan view, for example, ITO.
It is made of a transparent conductive material such as (Indium Tin Oxide). Switching element 4
7 is arranged in the inter-pixel region 11 and is provided to correspond to the pixel electrode 48 on a one-to-one basis. As described above, the orientation of the liquid crystal layer 6 can be regulated independently for each sub-pixel 10. The switching element 47 is an element made of TFT, for example, and is connected to a scanning line and a data line (not shown). The alignment film 46 is provided at the interface with the liquid crystal layer 6 and regulates the alignment of liquid crystal molecules constituting the liquid crystal layer 6.

The light reflecting layer 45 is a metal layer made of, for example, aluminum, and reflects light toward the color filter substrate 5 side. The light reflection layer 45 is formed on the liquid crystal layer 6 side of the pixel electrode 48 and is provided at an arbitrary ratio in a region in the sub-pixel 10 in a plan view. In FIG. It is provided in an area that occupies almost half of the area. This region is a light reflection region 10b. The region where the light reflection layer 45 is not provided is a light transmission region 10 a that transmits light from the backlight 3 to the liquid crystal layer 6 and the color filter substrate 5. The surface of the light reflecting layer 45 (the surface on the liquid crystal layer 6 side) is a reflecting surface, and an uneven pattern is formed on the reflecting surface. In addition, the thickness of each light reflection layer 45 is constant. Here, an example in which the light reflecting layer 45 is formed on the surface of the pixel electrode 48 is shown, but the light reflecting layer 45 is also shown.
May be formed under the pixel electrode 48.

On the other hand, the color filter substrate 5 is mainly composed of a base material 5a, a color filter layer 50, a light shielding film 51, a common electrode 58, and an alignment film 56. The base material 5a of the color filter substrate 5 is a rectangular plate-like member formed of a highly light-transmitting material such as glass or quartz, for example, like the base material 4a of the TFT array substrate 4. The color filter layer 50 is a color layer provided on the liquid crystal layer 6 side of the substrate 5a so as to overlap the subpixel 10 in plan view. The color filter layer 50 includes, for example, three color layers, a red layer 50R, a green layer 50G, and a blue layer 50B.

One sub-pixel 10 is provided with a color filter layer 50 of one of the three colors, and the red layer 50R, the green layer 50G, and the blue layer 50B are arranged in adjacent columns. Three sub-pixels 10 having color filter layers 50 adjacent to each other and having different color layers form a set, and 1
A pixel (one pixel) is configured. The light shielding film 51 is a light shielding member made of a material capable of reflecting or absorbing light, and is provided around the color filter layer 50.

The common electrode 58 is an electrode formed of a transparent conductive material such as ITO, for example,
It is provided so as to cover the color filter layer 50 and the light shielding film 51. In the region of the common electrode 58 that overlaps the light reflecting layer 45 in plan view, an insulating film transparent layer 58a is formed in the lower layer so that it is closer to the TFT array substrate 4 side than the other regions. Yes. As a result, the gap t2 of the liquid crystal layer 6 in the region where the light reflecting layer 45 is provided is smaller than the gap t1 of the liquid crystal layer 6 in other regions. The alignment film 56 is provided at the interface with the liquid crystal layer 6, and regulates the alignment of liquid crystal molecules constituting the liquid crystal layer 6 with the alignment film 46.

The liquid crystal layer 6 is made of liquid crystal molecules such as a fluorine-based liquid crystal compound and a non-fluorine-based liquid crystal compound, and is in contact with both the alignment film 46 on the TFT array substrate 4 side and the alignment film 56 on the color filter substrate 5 side. So as to be sandwiched between both substrates. The alignment of the liquid crystal molecules is regulated by the alignment film 46 and the alignment film 56 so as to block light (normally black mode) when no voltage is applied. Here, a vertical alignment film is used for the alignment film 46 and the alignment film 56, and a liquid crystal compound having a negative dielectric anisotropy is used.

[First Embodiment]
Here, a specific configuration for one sub-pixel at a position corresponding to a pattern to be displayed in the first embodiment will be described with reference to FIG. In the first embodiment, a protrusion 80 made of polyimide or the like is formed as a structure that disturbs the alignment of liquid crystal molecules between the light reflecting layer 45 and the alignment film 46 in the light reflecting region 10b. Since the alignment films 46 and 56 are vertical alignment films, the liquid crystal molecules are aligned perpendicular to the surfaces of the alignment films 46 and 56 when the liquid crystal display device 1 is in a non-driven state.

Then, the liquid crystal molecules located away from the protrusions 80 are aligned perpendicular to the TFT array substrate 4, but the liquid crystal molecules near the protrusions 80 are aligned perpendicular to the alignment film 46.
When viewed from the TFT array substrate 4, the orientation is inclined. Therefore, when the liquid crystal display device 1 is in a non-driven state, the light transmission region 10a and the light reflection region 10b in which the protrusions 80 are not formed display black because they do not transmit light, but the light in which the protrusions 80 are formed. Reflection area 1
In 0b, a part of the incident light from the outside is transmitted, reflected by the light reflecting layer 45, and leaked to the outside. For this reason, the light reflection area 1 of the sub-pixel corresponding to the pattern to be displayed in the display area.
By forming the protrusion 80 on 0b, a predetermined pattern can be displayed when the liquid crystal display device 1 is not driven. In order to increase light leakage, a plurality of the protrusions 80 may be formed so as to be distributed over the entire surface of the light reflection region 10b of the sub-pixel corresponding to the pattern to be displayed in the display region. .

An example of the state of the display area 9 when the power of the liquid crystal display device 1 configured as described above is turned off is shown in FIG. FIG. 4 shows the display area 9 in a state in which the power source of the liquid crystal display device 1 is turned off, that is, in a non-driving state in which no voltage is applied to the liquid crystal layer 6 between the TFT array substrate 4 and the color filter substrate 5. When the user of the liquid crystal display device 1 observes the display area 9, an arbitrary identification pattern formed in advance with respect to the background pattern 60 can be observed. In the first embodiment, a symbol composed of ABCDE is displayed as the identification pattern 70 as shown in FIG.

That is, normally, when the liquid crystal display device 1 is not driven, there is no light transmitted from the backlight 3 through the light transmission region 10a, and light from outside light reflected by the light reflection layer 45 in the light reflection region 10b is observed by the observer. It is only observed. At this time, if the projection 80 is formed in the light reflection region 10b of the sub-pixel 10 corresponding to the identification pattern 70, the reflected light from the light reflection region 10b where the projection 80 is formed is observed by the observer. The identification pattern 70 appears on the background pattern 60 and is observed.

Therefore, in the liquid crystal display device including the sub-pixels having the light transmission region 10a and the light reflection region 10b, the protrusion 80 corresponding to the identification pattern to be displayed when the power of the liquid crystal display device 1 is turned off is provided in the light reflection region 10b. In this way, even when the liquid crystal display device 1 is in a non-driven state, when incident light composed of external light is emitted, it is emitted as emitted light corresponding to the identification pattern. The pattern 70 can be displayed.

Note that when the protrusion 80 is formed in the light reflection region 10b of the sub-pixel in which the color filter layer of a specific color is formed, leakage light of the specific color is generated. Accordingly, by appropriately selecting a sub-pixel in which a protrusion is formed within one pixel, it is possible to generate a leak light having a desired color. Furthermore, if the color filter layer of the light reflection region 10b of the sub-pixel where the protrusion 80 is formed is removed, achromatic leakage light can be generated, and the pattern can be displayed in black and white.

In addition, when the power of the liquid crystal display device is turned on, the light transmission region 10a is transmitted from the backlight 3.
Various displays such as a normal moving image and a still image can be performed by the light emitted through. At this time, the light emitted through the light reflection region 10b by the external light is very weak compared to the light emitted through the light transmission region 10a, and therefore the identification mark is hardly observed by the user. Absent.

In addition, although the example which displayed the alphabet as the identification pattern 70 was shown in 1st Embodiment, it is not limited to such characters, such as an alphabet. According to the present invention, not only characters but also various patterns including corporate logo marks, floral patterns, checkered patterns, and the like can be observed by the user with the liquid crystal display device turned off. As described above, in the liquid crystal display device 1 according to the present invention, since the arbitrary identification pattern 70 can be displayed when the power is turned off, the power consumption can be greatly reduced.

In the first embodiment, the example in which the protrusion 80 is formed between the light reflecting layer 45 and the alignment film 46 is shown, but the protrusion 80 may be formed on the surface of the alignment film 46. In this case, the protrusion 80
Since there is no alignment film on the surface, liquid crystal molecules in the vicinity of the protrusions 80 are oriented in random directions. Accordingly, when the liquid crystal display device 1 is not driven, light is transmitted in the vicinity of the protrusion 80. Therefore, in the light reflection region 10b where the protrusion 80 is formed, a part of the incident light from the outside is transmitted and the light is transmitted. Reflected by the reflective layer 45 and leaks to the outside. Therefore, in the liquid crystal display device 1, an arbitrary identification pattern 70 can be displayed without applying a voltage to the liquid crystal layer 6.

In the first embodiment, an example in which the protrusion 80 is formed on the TFT array substrate 4 side is shown. However, the protrusion may be formed in the light reflection region 10 b of the color filter substrate 5. Even in this case, the protrusion can be formed on the surface of the alignment film 56 or between the alignment film 56 and the common electrode 58. The principle of light leakage due to the provision of the protrusion is first. This is the same as in the first embodiment.

[Second Embodiment]
In the first embodiment, an example is shown in which protrusions are formed as a configuration for disturbing the alignment of liquid crystal molecules in the light reflection region. However, the light reflection region can also be formed by forming a region where no alignment film is present in the light reflection region. The orientation of the liquid crystal molecules can be disturbed. A specific configuration for one sub-pixel at a position corresponding to a pattern to be displayed in the second embodiment in which an alignment film absent region is formed in the light reflection region will be described with reference to FIG. .

As described above, in the normal display region, the opposing surfaces of the TFT array substrate 4 and the color filter substrate 5 are separated from the vertical alignment film so as to shield light when not driven without applying voltage (normally black mode). Covered with the alignment film 46 and the alignment film 56 (
(See FIG. 2). In the second embodiment, at least a part of the alignment film 46 formed on the surface of the light reflection layer 45 in the light reflection region 10b at a position corresponding to the pattern to be displayed is removed, and the alignment film is not present. A portion 46a is formed.

Then, the liquid crystal molecules located away from the alignment film non-existing portion 46a are transferred to the TFT array substrate 4.
The liquid crystal molecules of the alignment film absent portion 46a are oriented in a random direction. Therefore, when the liquid crystal display device 1 is in a non-driven state, the light reflection region 10b on which the light transmission region 10a and the alignment film 46 are formed displays black because it does not transmit light, but the alignment film absence portion 46a. In the light reflection region 10b in which is formed, a part of the incident light from the outside is transmitted and reflected by the light reflection layer 45 and leaks to the outside. Therefore, by forming the alignment film non-existing portion 46a on a part or the whole surface of the light reflecting region 10b of the sub-pixel corresponding to the pattern to be displayed in the display region, the predetermined pattern is obtained when the liquid crystal display device 1 is not driven. Can be displayed.

Also in this case, the alignment film non-existing portion 46 a is formed on the TFT array substrate 4 side, but the alignment film non-existing portion 46 a may be formed in the light reflection region 10 b of the color filter substrate 5. Also in this case, the principle of light leakage due to the provision of the alignment film absent portion 46a is the same as that in the case where the alignment film absent portion 46a is formed on the TFT array substrate 4 side.

Although the VA mode has been described as the first and second embodiments, the present invention is equally applicable to a normally black mode transflective liquid crystal display device.
Other semi-transmissive liquid crystal display devices of such a normally black mode include, for example, IP
A transflective liquid crystal display device in a transverse electric field mode such as an S mode or an FFS mode can be given.

Heretofore, an example of a transflective liquid crystal display device has been described as an embodiment of the present invention. Such a transflective liquid crystal display device of the present invention can be used for electronic devices such as personal computers, mobile phones, and portable information terminals. Among these, an example in which the transflective liquid crystal display device 71 is used in the personal computer 70 is shown in FIG. 6A, and an example in which the transflective liquid crystal display device 76 is similarly used in the mobile phone 75 is shown in FIG. However, since the basic configuration of the personal computer 70 and the mobile phone 75 is well known to those skilled in the art, a detailed description thereof will be omitted.

It is a figure which shows the whole structure of a liquid crystal display device. It is a schematic cross section along the II-II line of FIG. FIG. 3 is a schematic cross-sectional view for one sub-pixel at a position corresponding to a pattern to be displayed according to the first embodiment. It is a top view which shows the display state at the time of the non-driving of the liquid crystal display device of 1st Embodiment. It is a schematic cross section for one sub pixel of the position corresponding to the pattern which wants to be displayed concerning a 2nd embodiment. 6A is a diagram showing a personal computer equipped with the liquid crystal display device of the present invention, and FIG. 6B is a diagram showing a mobile phone equipped with the liquid crystal display device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device 2 ... Liquid crystal panel 3 ... Backlight 4 ... TFT array substrate 5 ...
Color filter substrate 6 ... Liquid crystal layer 9 ... Display area 10 ... Sub-pixel 10a ... Light transmission area
10b ... Light reflection region 45 ... Light reflection layer 46 ... Alignment film 50 ... Color filter layer 50R
... Red layer 50G ... Green layer 50B ... Blue layer 60 ... Background pattern 70 ... Identification pattern 80: Projection

Claims (5)

In the liquid crystal display device of a normally black mode in which the sub-picture element is provided with a display area arranged in a matrix having a light reflecting region and a light transmitting region,
The sub-pixel is
A liquid crystal layer sandwiched between the first substrate and the second substrate facing each other;
An alignment film provided at an interface between the first substrate and the liquid crystal layer, and an interface between the second substrate and the liquid crystal layer;
When the subpixel corresponds to a pattern to be displayed in the display area when the liquid crystal display device is not driven , a protrusion formed below or on the surface of the alignment film in the light reflection area;
Have
When the liquid crystal display device is driven, an arbitrary image is displayed on the display region by light emitted from the backlight through the light transmission region, and when the liquid crystal display device is not driven, the light reflection region is passed through the light reflection region. The pattern is displayed in the display area by reflected light of outside light emitted in this way,
Liquid crystal display device. 2. The liquid crystal display device according to claim 1, wherein a plurality of the protrusions are dispersedly arranged in the light reflection region of the sub-pixel corresponding to the pattern. The liquid crystal display device according to claim 1, wherein a color filter layer in a light reflection region of the sub-pixel corresponding to the pattern is removed. The liquid crystal display device according to claim 1, which is driven in a vertical alignment mode or a lateral electric field mode. The electronic device provided with the liquid crystal display device in any one of Claims 1-4.

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