JP2003215607A - Liquid crystal display device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent thickness accuracy and thickness uniformity of a liquid crystal layer from being degraded caused by infiltration of a gap material in a sealing material into a cholesteric liquid crystal layer side or a hologram layer side when two substrates with the cholesteric liquid crystal layer or the hologram layer disposed on each are stuck with each other via the sealing material in a liquid crystal display device. <P>SOLUTION: In the liquid crystal display device provided with a semitransmissive-reflective layer 18 with the cholesteric liquid crystal layer or the hologram layer, a reinforcing layer 50 composed of a metal film or an organic film with ≥2H pencil hardness is disposed between the semitransmissive-reflective layer 18 and the sealing material 15. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and an electronic device in which a liquid crystal layer side surface of a substrate constituting a liquid crystal cell is provided with a collective liquid crystal layer and a hologram layer. The fibers and beads in the material are prevented from sinking into the cholesteric liquid crystal layer side or the hologram layer side so that the accuracy and uniformity of the thickness of the liquid crystal layer can be improved.

[0002]

2. Description of the Related Art Reflective liquid crystal display devices have low power consumption because they do not have a light source such as a backlight, and have been widely used in various portable electronic devices. However,
The reflective liquid crystal display device uses external light such as natural light or illumination light for display, and thus has a problem that it is difficult to visually recognize the display in a dark place. Therefore, there has been proposed a liquid crystal display device in which outside light is used in a bright place like a normal reflection type liquid crystal display device, and a display can be visually confirmed by an internal light source in a dark place. In other words, this liquid crystal display device employs a display system that has both a reflective type and a transmissive type, and the power consumption can be reduced by switching the display mode to either the reflective mode or the transmissive mode according to the ambient brightness. It is possible to perform a clear display even when the surroundings are dark while reducing the number. Hereinafter, in this specification, this type of liquid crystal display device is referred to as a “semi-transmissive reflective liquid crystal display device”.

As a form of the transflective liquid crystal display device,
A reflective film having a slit (opening) for light transmission formed on a metal film such as aluminum is referred to as an inner surface of the lower substrate (hereinafter, in this specification, a surface of the substrate on the liquid crystal side is an inner surface, and a surface opposite to the outer surface is an outer surface). Therefore, a liquid crystal display device in which this reflective film functions as a semi-transmissive reflective film has been proposed. This type of liquid crystal display device has an effect of preventing the effect of parallax due to the thickness of the lower substrate by providing a metal film on the inner surface of the lower substrate, and in particular, in the structure using a color filter, preventing color mixing. .

By the way, as a reflective layer of such a transflective liquid crystal display device, a metal film having a high light reflectance such as aluminum or silver has been conventionally used. On the other hand, in recent years, dielectric mirrors in which dielectric thin films having different refractive indexes are alternately laminated, cholesteric reflectors using cholesteric liquid crystals, hologram reflectors composed of hologram layers, and the like have been proposed. These reflectors not only serve as reflectors that reflect light by taking advantage of the characteristics of the constituent materials, but also have other functions.

Cholesteric liquid crystals exhibit a liquid crystal phase at a certain temperature (liquid crystal transition temperature) or more, and in the liquid crystal phase, liquid crystal molecules have a periodic spiral structure with a constant pitch. This structure has a property of selectively reflecting light having a wavelength matching the pitch of the helix and transmitting other light. Therefore, since the pitch of the helix can be controlled by, for example, the intensity of ultraviolet rays during curing and the temperature, the color of the reflected light can be locally changed, and it is also used as a reflective color filter. Further, by stacking a plurality of cholesteric liquid crystal layers that selectively reflect color lights of different colors, it is possible to eventually function as a reflection plate that reflects white light.

Further, the hologram layer reflects incident light in a direction deviated from the specular reflection direction according to the pitch of interference fringes formed in the layer, so-called off-axis (Off Axi).
It has the function of s). Further, by changing the pitch of the interference fringes, it is possible to reflect light of different wavelengths, and like the cholesteric liquid crystal, it can be used as a reflective color filter.

[0007]

However, in a reflective liquid crystal display device using such a cholesteric liquid crystal layer, patterning is difficult to form the cholesteric liquid crystal layer, and therefore the cholesteric liquid crystal layer is formed on the entire surface of the substrate. I have no choice but to form. Therefore, when the one substrate on which the cholesteric liquid crystal layer is formed and the other substrate are bonded together via the sealing material including the gap material, the sealing material is provided on the cholesteric liquid crystal layer. Since the hardness of the cholesteric liquid crystal layer is comparatively low, the gap material in the sealing material may dent into the cholesteric liquid crystal layer side. Usually, the sealing material contains a relatively hard gap material such as glass fiber so that the distance between the upper substrate and the lower substrate becomes a predetermined liquid crystal layer thickness. Therefore, the fact that the sealing material is embedded in the cholesteric liquid crystal layer specifically means that the glass fiber or the like contained in the sealing material is embedded. As a result, the distance between the one substrate and the other substrate, that is, the thickness of the liquid crystal layer becomes smaller than a predetermined thickness, or the uniformity becomes poor, resulting in a decrease in contrast and display unevenness on the liquid crystal display screen. There was a problem of causing it.

Such a problem is not limited to a passive matrix type or active matrix type reflective liquid crystal display device using a cholesteric liquid crystal layer, but is a problem of a passive matrix type or active matrix type semi-display using a cholesteric liquid crystal layer. The same applies to the transflective liquid crystal display device. Further, the same applies to the configuration in which the hologram layer is formed as the reflection layer or the color filter layer on the substrate that constitutes the liquid crystal cell. That is, when one substrate on which the hologram layer is formed and the other substrate are bonded via a sealing material, the hologram layer is relatively flexible and has a hardness that can withstand the pressure applied in the bonding step. Since there is no gap, there is a problem that the gap material in the seal material is embedded in the hologram layer side.

The present invention has been made to solve the above problems, and in a liquid crystal display device in which a cholesteric liquid crystal layer or a hologram layer is provided on a substrate, two substrates are pasted together with a sealing material. An object of the present invention is to provide a liquid crystal display device capable of preventing a decrease in thickness accuracy and thickness uniformity of a liquid crystal layer due to a gap material in a sealing material penetrating into a cholesteric liquid crystal layer side or a hologram layer side at the time of matching. And

[0010]

In order to solve the above-mentioned problems, a liquid crystal display device of the present invention is provided between an upper substrate and a lower substrate which face each other and are adhered by a frame-like sealing material. A liquid crystal display device having a liquid crystal cell in which a liquid crystal layer is sandwiched, wherein a cholesteric liquid crystal layer that reflects at least a part of elliptically polarized light having a predetermined rotation direction is provided on the liquid crystal layer side surface of the lower substrate. An upper substrate-side elliptically-polarized light incidence unit that makes elliptically polarized light incident on the liquid crystal layer from the upper substrate side is provided, and the liquid crystal layer is in a selective electric field applied state or a non-selective electric field-applied state. The polarity of the elliptically polarized light that has entered in one of the states is reversed, and the polarity is not changed in the other state. A metal film or pencil hardness of 2H or more is provided between the reflective layer and the sealing material. Wherein the reinforcing layer made of an organic film is provided.

The cholesteric liquid crystal used in the present invention has so-called selective reflectivity that selectively reflects circularly polarized light having a wavelength equal to the helical pitch of liquid crystal molecules and the same rotation direction as the spiral winding direction. There is. Conversely,
Light having a wavelength not equal to the helical pitch of the liquid crystal molecules, and circularly polarized light having a rotation direction opposite to the spiral winding direction even though the wavelength is equal to the helical pitch of the liquid crystal molecules pass through the cholesteric liquid crystal. Further, the cholesteric liquid crystal layer used in the present invention has a wavelength equal to the helical pitch of liquid crystal molecules,
It has a function of reflecting at least a part of circularly polarized light in the same rotation direction as the spiral winding direction. Therefore, in the case of a cholesteric liquid crystal layer that has a wavelength equal to the helical pitch of liquid crystal molecules and reflects all circularly polarized light in the same rotation direction as the spiral winding direction, it functions as a reflective layer and the wavelength is the helical pitch of liquid crystal molecules. And a cholesteric liquid crystal layer that reflects a part of circularly polarized light in the same rotation direction as the spiral winding direction, it functions as a semi-transmissive reflective layer.

In the structure provided with the reflective layer having the cholesteric liquid crystal layer, both the light introduced into the liquid crystal layer from the upper substrate side and the lower substrate side is "elliptical polarized light", but in reality, it is "circular polarized light". However, the above light does not necessarily have to be perfectly circularly polarized light, and may be “elliptical polarized light” in a broad sense. Further, the light reflected by the cholesteric liquid crystal layer is "elliptical polarized light having a predetermined rotation direction", but actually it is approximately "circular polarized light having a predetermined rotation direction". However, the light reflected by the cholesteric layer does not necessarily have to be perfect circularly polarized light, and in a broad sense is "elliptic polarized light".
If

According to the present invention, when the two substrates are bonded together via the sealing material, even if a pressing force is applied to press the sealing material toward the cholesteric liquid crystal layer side, the reflection layer and the sealing layer having the cholesteric liquid crystal layer are sealed. By providing the reinforcing layer with the material, it is possible to prevent the gap material in the sealing material from sinking into the cholesteric liquid crystal layer side.
Therefore, the thickness accuracy and the thickness uniformity of the liquid crystal layer can be improved, and the contrast and the display unevenness on the liquid crystal display screen can be improved.

In the present invention, the reflective layer may be a semi-transmissive reflective layer having a cholesteric liquid crystal layer that reflects a part of elliptically polarized light having a predetermined rotation direction and transmits a part thereof. Thus, a transflective liquid crystal display device can be constructed. In this case, a lower substrate side elliptically polarized light incident means for making the elliptically polarized light incident from the lower substrate side is provided.

Another liquid crystal display device of the present invention is a liquid crystal cell in which a liquid crystal layer is sandwiched between an upper substrate and a lower substrate which are opposed to each other and are pasted together by a frame-shaped sealing material. A liquid crystal display device having the above, wherein a reflective layer having a hologram layer is provided on a surface of the lower substrate on the liquid crystal layer side, and a metal film or an organic material having a pencil hardness of 2H or more is provided between the reflective layer and a sealing material. It is characterized in that a reinforcing layer made of a film is provided.

According to the present invention, similarly to the case where the cholesteric layer is provided, when the two substrates are pasted together via the sealing material, even if the sealing material is pressed against the hologram layer side, a hologram is generated. By providing the reinforcing layer between the reflective layer having a layer and the sealing material, it is possible to prevent the gap material in the sealing material from sinking into the hologram layer side. Therefore, the thickness accuracy and the thickness uniformity of the liquid crystal layer can be improved, and the contrast and the display unevenness on the liquid crystal display screen can be improved.

In the present specification, the organic film refers to a film formed of an organic material. As the metal film, for example, chromium (Cr), tantalum (Ta), aluminum (A
1), silver (Ag) and the like are preferable.

The thickness of the reinforcing layer depends on the hardness of the film in order to obtain the effect of preventing the sealing material from slipping in.
It is preferably 0.05 μm or more. In the case of a metal film, the upper limit of the film thickness is preferably set so as not to cause a short circuit with the conductive film on the counter substrate. The width of the reinforcing layer in the width direction of the sealing material should be 0.8 or more when the width of the sealing material is 1 in order to obtain the effect of preventing the sealing material from slipping in. Preferably there is. The grounds for these numerical ranges are described in [Example] below.
Will be described in detail in the section.

Further, the reinforcing layer does not necessarily have to be formed in the entire region which overlaps with the sealing material when seen in a plan view, and may be partially provided in the region. In a region overlapping with the sealing material, when the reinforcing layer is partially provided, in a part of the sealing material,
The position where the reinforcing layer is formed is set so that the penetration can be prevented but the penetration cannot be prevented in other portions. Specifically, in a plan view of the sealing material, the reinforcing layer is substantially point-symmetric with respect to the center of the region surrounded by the sealing material, and It is preferable to design the reinforcing layer to be present in all of the sections when it is divided into four sections by two straight lines passing through each other so that the thickness of the liquid crystal layer in the entire screen becomes uniform. Therefore, it is possible to improve the contrast and display unevenness.

An electronic apparatus of the present invention is characterized by including the liquid crystal display device of the present invention having any one of the above configurations.
According to such a configuration, the sealing material is prevented from penetrating into the cholesteric liquid crystal layer, so that the liquid crystal layer is formed to have a predetermined thickness, and the liquid crystal device is provided with a good uniformity of the thickness of the liquid crystal layer. An electronic device with good display characteristics can be obtained.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. 1A and 1B show a schematic configuration of a liquid crystal display device 10 of the present embodiment, where FIG. 1A is a plan view and FIG.
It is sectional drawing which follows the HH 'line in (a). FIG. 2 is a cross-sectional view showing an enlarged main part of FIG. This embodiment is an example of an active matrix type transflective liquid crystal display device using a thin film transistor (TFT) as a switching element.
In all of the following drawings, in order to make the drawings easy to see, the film thicknesses, the dimensional ratios, and the like of the respective constituent elements are appropriately changed.

Reference numeral 11 in the drawing is a liquid crystal cell, and the lower substrate 1
3 and the upper substrate 14 are fixed in a state of being opposed to each other via a sealing material 15, and the upper substrate 14 and the lower substrate 1
3. TN (Twisted Nema) in the space surrounded by the sealing material 15.
tic) A liquid crystal layer 16 made of liquid crystal or the like is enclosed. The sealing material 15 is formed of an epoxy resin or the like containing the gap material 15a. The gap material 15a in the sealing material 15 is contained to make the gap between the lower substrate 13 and the upper substrate 14 constant, and has a diameter of 2 to 10 μm, for example.
m, a glass fiber or the like having a length of about 10 to 100 μm is preferably used.

A sealing material 15 is provided on the lower substrate 13 along the edge thereof, and a data line driving circuit 51 and an external circuit connecting terminal 52 are provided on the lower substrate 13 in an area outside the sealing material 15. It is provided along one side, and the scanning line driving circuit 54 is provided along two sides adjacent to this one side. A plurality of wirings 55 for connecting the scanning line drive circuits 54 provided on both sides of the image display area are provided on the remaining one side of the lower substrate 13. Further, at least one location of the corner portion of the upper substrate 14 is provided with a conductive material 56 for establishing electrical conduction between the lower substrate 13 and the upper substrate 14. The liquid crystal display device of the present embodiment is a semi-transmissive reflection type, and although not shown, a backlight (illumination device) is provided on the back surface side of the liquid crystal cell 11, that is, the outer surface side of the lower substrate 13. .

The lower substrate 13 is made of a translucent material such as glass or plastic, and a semi-transmissive reflective layer 18 in which an alignment film and a cholesteric liquid crystal layer are alternately formed is provided on the inner surface of the lower substrate 13. There is. The plurality of cholesteric liquid crystal layers forming the semi-transmissive reflective layer 18 have different helical pitches of liquid crystal molecules. For example, a layer in which the helical pitch of liquid crystal molecules is about 450 nm is blue light, 550 n
The layer having a thickness of about m selectively reflects green light, and the layer having a thickness of about 650 nm selectively reflects red light, so that white light as a whole is selectively reflected. Further, each cholesteric liquid crystal layer reflects a part of circularly polarized light having a predetermined rotation direction and transmits a part thereof. In the present embodiment, for example, clockwise circularly polarized light (hereinafter, right circularly polarized light). Of the polarized light), 80% is reflected and 20% is transmitted. Therefore, the entire semi-transmissive reflective layer 18 has a function of reflecting 80% of white right-handed circularly polarized light and transmitting 20% thereof. The thickness of the semi-transmissive reflective layer 18 is, for example, 5 to 20 μm.
It is about m.

In order to form the semi-transmissive reflective layer 18, for example, an alignment film is applied on a glass plate, a plastic sheet or the like which constitutes the lower substrate 13, the alignment film is rubbed, and then the alignment film is formed. A solution containing a cholesteric liquid crystal is applied to the surface of the film by various coating methods such as a spin coater, and then, the solution is irradiated with ultraviolet rays to be cured to form a cholesteric liquid crystal layer. Here, by controlling the pitch of the spirals of the liquid crystal molecules by controlling the intensity of the ultraviolet rays and the temperature when curing by irradiating with ultraviolet rays, the liquid crystal molecules adopt a periodic spiral structure at a constant pitch. To do. Then, the formation of the alignment film subjected to such a rubbing treatment and the formation of the cholesteric liquid crystal layer are alternately repeated to obtain the desired semi-transmissive reflective layer 18.

Although not shown, data lines, scanning lines, pixel electrodes, switching TFTs, etc. are formed on the semi-transmissive reflective layer 18 on the liquid crystal layer 16 side, and the innermost layer (the liquid crystal layer 1) is formed.
As the uppermost layer on the 6 side), an alignment film made of polyimide or the like is laminated. Further, if necessary, the semi-transmissive reflective layer 1
On the liquid crystal layer 16 side of No. 8, an overcoat layer, a color filter layer, a flattening film and the like may be formed. Then, the reinforcing layer 50 is formed between the semi-transmissive reflective layer 18 and the sealing material 15 in a region overlapping the sealing material 15 when the liquid layer cell 11 is viewed in a plan view. The reinforcing layer 50 is formed below the alignment film which is the innermost layer. In the present embodiment, as shown in FIG. 1, when the liquid layer cell 11 is viewed in a plan view, the region overlapping the sealing material 15 has a substantially rectangular band shape, and the reinforcing layer 50 has the rectangular band shape region. Out of
The data line drive circuit 51 and the external circuit connection terminal 52 are provided at both ends of two strip-shaped portions extending in parallel with the side on which the data circuit drive terminal 51 and the external circuit connection terminal 52 are formed.

The reinforcing layer 50 is formed of a metal film or a relatively hard organic film. The metal material for forming the metal film is not particularly limited as long as it has a hardness that can prevent the gap material 15a in the seal material 15 from slipping into the semi-transmissive reflection layer 18 side. For example, chromium (Cr), Tantalum (Ta), aluminum (Al), silver (Ag), etc.
Since it is a metal conventionally used in the construction of liquid crystal display devices, it is preferable because it is easily available and can be used as a film forming device. On the other hand, if the hardness of the organic film forming the reinforcing layer 50 is insufficient, it is impossible to prevent the gap material in the sealing material 15 from penetrating into the semi-transmissive reflective layer 18 side. Therefore, a pencil hardness of 2H or more is preferably used. . The organic material forming the organic film is not particularly limited as long as it can achieve a pencil hardness of 2H or more, but an acrylic resin having a high hardness is particularly preferable.

The thickness of the reinforcing layer 50 depends on the hardness thereof, but in order to obtain the effect of preventing the gap material 15a in the sealing material 15 from sinking into the semi-transmissive reflection layer 18 side,
The thickness is preferably 0.05 μm or more. If the thickness of the reinforcing layer 50 is too large, the gap material cannot be used to realize a predetermined thickness of the liquid crystal layer.
The following is preferable. In particular, when the reinforcing layer 50 is formed of a metal film, if the reinforcing layer 50 (metal film) is too thick, a short circuit may occur with a conductive film such as wiring provided on the inner surface of the upper substrate 14. is there. Generally, the liquid crystal layer 1
Since the thickness of 6 is designed to be about 3 to 8 μm, if the thickness of the reinforcing layer 50 made of a metal film is 2 μm or less, a short circuit can be prevented even when the design value of the thickness of the liquid crystal layer 16 is as thin as 3 μm. can do.

Reinforcing layer 50 in the width direction of the sealing material 15
In order to obtain the effect of preventing the gap material 15a in the sealing material 15 from sinking into the semi-transmissive reflective layer 18, the width of the width of the reinforcing material 50 is 1 when the width of the sealing material 15 is 1. It is preferable that the ratio is 0.8 or more. Reinforcing layer 50
The width of may be the same as the width of the sealing material 15, and the sealing material 1
The width of the reinforcing layer 50 may be larger than the width of 5, but if it is too large, the area that does not contribute to the display of the liquid crystal display device increases. Therefore, the upper limit of the width of the reinforcing layer 50 is about 1.2 when the width of the sealing material 15 is 1. It is preferable that

The liquid crystal display device of the present embodiment is of a semi-transmissive reflection type, and serves as a lower substrate side elliptically polarized light incident means means for making elliptically polarized light incident on the liquid crystal layer 16 from the lower substrate 13 side.
On the outer surface side of the lower substrate 13 (the side opposite to the liquid crystal layer 16),
The four-wave plate 27 and the lower polarizing plate 28 are provided in this order. In the present embodiment, the transmission axis of the lower polarizing plate 28 is parallel to the plane of the paper of FIG. 2, and the linearly polarized light in this direction is the lower 1/4.
Right circularly polarized light is emitted when the light enters the wave plate 27. An arbitrary retardation plate may be used in place of the lower quarter wave plate 27. In this case, this retardation plate has a function of converting linearly polarized light transmitted through the lower polarizing plate 28 into circularly polarized light. Is used.

The upper substrate 14 is made of a light-transmissive material such as glass or plastic, and on its inner surface side (the liquid crystal layer 16 side), a counter electrode (not shown) is formed and a polyimide is used as the innermost layer. An alignment film made of, for example, is laminated. Further, if necessary, an overcoat layer, a color filter layer, a flattening film and the like may be formed on the inner surface side of the upper substrate 14.

The liquid crystal layer 1 is formed on the outer surface of the upper substrate 14.
As the upper substrate side elliptically polarized light incidence means for making the elliptically polarized light incident on 6 from the upper substrate 14 side, an upper quarter wavelength plate 35,
The upper polarizing plate 36 is provided in this order from the upper substrate 14 side. In the present embodiment, the transmission axis of the upper polarizing plate 36 is set in a direction parallel to the paper surface of FIG. 2, and when linearly polarized light in this direction is incident on the upper ¼ wavelength plate 35, right circularly polarized light is emitted. ing. An arbitrary retardation plate may be used instead of the upper quarter-wave plate 35. In this case, this retardation plate has a function of converting linearly polarized light transmitted through the upper polarizing plate 36 into circularly polarized light. If you have.

The liquid crystal layer 16 is for reversing the rotation direction of the circularly polarized light that has entered depending on whether or not a selective electric field is applied. For example, when the non-selective voltage is applied (when the liquid crystal is OFF), the liquid crystal molecules lie down, for example, λ / 2. Therefore, the incident right circularly polarized light is changed to left circularly polarized light after passing through the liquid crystal layer, and left circularly polarized light is changed to right circularly polarized light. On the other hand, the phase difference disappears when the selection voltage is applied (when the liquid crystal is ON), and the rotation direction of the circularly polarized light does not change.

Here, the display principle of the liquid crystal display device of the present embodiment will be described with reference to FIG. Here, the color filter layer 30 is provided on the inner surface of the lower substrate 13, and when light entering the liquid crystal cell from the outside of the upper substrate 14 and the outside of the lower substrate 13 enters the color filter layer 30, , R will be described below. Figure 3
In the liquid crystal display device of the present embodiment shown in FIG. 3, when performing bright display in the reflection mode (the left end of FIG. 3), the upper substrate 14
Light incident from the outside of the upper polarizing plate 36 on the upper substrate 14
To become linearly polarized light having a polarization axis parallel to the paper surface, and then to pass through the upper quarter-wave plate 35 to become right circularly polarized light. At this time, when the liquid crystal is kept in the ON state, the rotation direction of the circularly polarized light does not change as described above. Therefore, when the right circularly polarized light is incident on the liquid crystal layer, this light passes through the liquid crystal layer 16 and the color filter layer 30. Even after reaching the semi-transmissive reflective layer 18, the circularly polarized light remains right circularly polarized.

Therefore, after 80% of the red right circularly polarized light obtained by passing the right circularly polarized light through the R dye layer is reflected by the semi-transmissive reflective layer 18 on the lower substrate 13, the liquid crystal is again directed to the upper substrate 14. It will pass through layer 16. At this time as well, since the liquid crystal is in the ON state, the polarization state remains unchanged as right-handed circularly polarized light, but thereafter it changes to linearly polarized light having a polarization axis parallel to the paper surface by passing through the upper ¼ wavelength plate 35. Since this linearly polarized light can pass through the upper polarizing plate 36, it returns to the outside (observer side) and the liquid crystal display device displays bright (red).

On the contrary, in the case of performing the dark display in the reflection mode (second from the right in FIG. 3), if the liquid crystal is turned off,
Since the liquid crystal layer 16 has a phase difference of λ / 2, right circularly polarized light incident from the upper substrate 14 side becomes left circularly polarized light when transmitted through the liquid crystal layer 16. In FIG. 3, the cholesteric liquid crystal forming the semi-transmissive reflective layer 18 reflects only a part of the right circularly polarized light, so that the left circularly polarized light passes through the semi-transmissive reflective layer 18. After that, by passing through the lower quarter wave plate 27, it is changed to linearly polarized light having a polarization axis perpendicular to the paper surface,
Since this linearly polarized light is absorbed by the lower polarization plate 28, it does not return to the outside (observer side), and the liquid crystal display device displays a dark image.

On the other hand, when displaying in the transmission mode, the light emitted from the backlight enters the liquid crystal cell 11 from the outside of the lower substrate 13, and this light becomes the light that contributes to the display. Here, when dark display in the transmissive mode is performed (right end in FIG. 3), substantially the same action as in the reflective mode occurs from the lower substrate side to the upper substrate side. That is, FIG.
In the above, the lower polarizing plate 28 is the same on the lower substrate side as on the upper substrate side.
Since the lower quarter wave plate 27 is provided, the liquid crystal layer 1
Right circularly polarized light is incident on the lower substrate 6 from the lower substrate side, and 20% of the light is transmitted through the semi-transmissive reflective layer 16. Here, if the liquid crystal is in the OFF state, it becomes left circularly polarized light when it reaches the upper substrate side,
By passing through the upper quarter-wave plate 35, it changes into linearly polarized light having a polarization axis perpendicular to the paper surface, and since this linearly polarized light is absorbed by the upper polarizing plate 36, it is emitted to the outside (viewer side). Instead, the liquid crystal display device is darkly displayed.

When the bright display in the transmission mode is performed (second from the left in FIG. 3), the light incident from the lower substrate side is transmitted through the lower polarizing plate 28 to form a straight line having a polarization axis parallel to the paper surface. It becomes polarized light, and then passes through the lower quarter wave plate 27 to be emitted as right circularly polarized light. 20% of the emitted light can be transmitted through the semi-transmissive reflective layer 18 made of cholesteric liquid crystal, further transmitted through the dye layer of the color filter layer 30, and emitted as red right circularly polarized light. When the liquid crystal is in the ON state, 20% of right circularly polarized light reaches the upper substrate 14 side while maintaining the polarized state. After that, the right-handed circularly polarized light passes through the upper quarter-wave plate 35 to be changed into linearly polarized light having a polarization axis parallel to the paper surface, and this linearly polarized light can pass through the upper polarizing plate 36. ), The liquid crystal display is displayed bright (red).

By the way, in the transmissive mode bright display, 80% of the right circularly polarized light is reflected by the semi-transmissive reflective layer 18 made of cholesteric liquid crystal. At this time, as described above, the cholesteric liquid crystal has a property of not changing the rotation direction of the reflected circularly polarized light, and therefore the reflected light is right circularly polarized light. Therefore, thereafter, when the right circularly polarized light passes through the lower quarter wave plate 27, it becomes linearly polarized light having a polarization axis parallel to the paper surface, and this linearly polarized light passes through the lower polarizing plate 28 having a transmission axis parallel to the paper surface. can do. In this way, when the linearly polarized light having the same polarization axis as the transmission axis of the lower polarizing plate 28 is emitted from the lower substrate side, the light is reflected by the reflection plate provided in the backlight to the liquid crystal cell side. It can be reintroduced and reused for display.

As described above, in the liquid crystal display device of the present embodiment, the same display mode can be used during reflection and during transmission, and particularly when attention is paid to the bright display in the transmission mode, the conventional transflective liquid crystal is used. Unlike the display device, part of the light incident from the lower substrate side is not absorbed by the upper polarizing plate, and almost all the light transmitted through the semi-transmissive reflective layer 18 made of cholesteric liquid crystal contributes to the display. On the other hand, the light reflected by the semi-transmissive reflective layer 18 made of cholesteric liquid crystal can be reused for display. Therefore, the liquid crystal display device according to the present embodiment has the semi-transmissive reflective layer 1 made of cholesteric liquid crystal.
8 can be utilized to the maximum and the circularly polarized light reflected by the semi-transmissive reflective layer 18 can be reused for display, and thus the brightness of the reflective display can be maintained while maintaining the brightness of the reflective display. It is possible to realize a semi-transmissive reflective liquid crystal display device that has improved brightness and has excellent visibility.

According to this embodiment, the sealing material 15
Since the reinforcing layer 50 is formed between the semi-transmissive reflective layer 18 and the semi-transmissive reflective layer 18, the gap material 15a in the seal material 15 is cholesteric even if the sealing material 15 is pressed against the semi-transmissive reflective layer 18 side. Semi-transmissive reflective layer 1 having liquid crystal layer
It is prevented from slipping into the 8 side. Therefore, the liquid crystal layer 1
The thickness of 6 is the gap material 15 included in the seal material 15.
The thickness is defined by the diameter of a, and the thickness of the liquid crystal layer 16 is uniform in the entire liquid crystal cell 11. Therefore, it is possible to prevent deterioration of contrast and display unevenness due to defective thickness of the liquid crystal layer 16 and improve visibility.

The formation position and the planar shape of the reinforcing layer 15 are not limited to the example of the present embodiment, and the effect of preventing the semi-transmissive reflective layer 18 from being intruded into the entire sealing material 15 can be achieved. Can be changed appropriately. Seal material 1
In order to reinforce the entire No. 5 in good balance, the reinforcing material 50
Is substantially symmetrical with respect to the center of the region surrounded by the sealing material 15, and the sealing material 15 is divided into four sections by two straight lines passing through the center and orthogonal to each other. It is preferable to form the reinforcing layer 50 in all the compartments. For example, as shown in a modified example in FIG. 4, the reinforcing layer 50 is formed in each of the regions that overlap two opposing sides (short sides in the example of FIG. 4) of the substantially rectangular strip region that overlaps the sealing material 15. Alternatively, as shown in FIG. 5, the reinforcing layer 50 may be formed at each of the four corners of the substantially rectangular band-shaped region overlapping the sealing material 15.
However, when the reinforcing layer 15 has conductivity, wirings and electrodes provided on the lower substrate 13 and the upper substrate 14,
It is necessary to set the formation position and shape of the reinforcing layer 50 so that a short circuit does not occur between the conductive material 56 and the like provided at the corners of the sealing material 15.

[Electronic Equipment] Examples of electronic equipment provided with the liquid crystal display device of the above embodiment will be described. FIG. 6 is a perspective view showing an example of a mobile phone. In FIG. 6, reference numeral 1000 indicates a mobile phone main body, and reference numeral 1001 indicates a liquid crystal display unit using the above liquid crystal display device.

FIG. 7 is a perspective view showing an example of a wrist watch type electronic device. In FIG. 7, reference numeral 1100 indicates a watch body, and reference numeral 1101 indicates a liquid crystal display unit using the above liquid crystal display device.

FIG. 8 is a perspective view showing an example of a portable information processing device such as a word processor and a personal computer. In FIG. 8, reference numeral 1200 is an information processing apparatus, reference numeral 1202 is an input unit such as a keyboard, reference numeral 1204 is an information processing apparatus main body, and reference numeral 1206 is a liquid crystal display unit using the above liquid crystal display device.

The electronic equipment shown in FIGS. 6 to 8 is provided with a reinforcing layer between the cholesteric liquid crystal layer and the sealing material, and the liquid crystal layer is improved in thickness accuracy and thickness uniformity. Since the liquid crystal display device 10 is provided in the liquid crystal display unit, the liquid crystal layer is formed to have an appropriate thickness, so that an electronic device having excellent visibility can be obtained with high yield.

In the above embodiment, the liquid crystal display device can be constructed by using a semi-transmissive reflective layer having a hologram layer instead of the semi-transmissive reflective layer having a cholesteric liquid crystal layer, and similar to the cholesteric liquid crystal layer. Similarly, by providing the reinforcing layer 50 between the hologram layer having flexibility and the sealing material 15, the gap material 15a in the sealing material 15 is prevented from intruding, and the thickness accuracy and thickness of the liquid crystal layer 16 are improved. Uniformity can be improved.

Further, the technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. The present invention is not limited to the active-matrix transflective liquid crystal display device in which the TFT is used as a switching element as in the above embodiment, and the active-matrix method using a thin film diode as a switching element is not limited thereto. The present invention can also be applied to the semi-transmissive reflection type liquid crystal display device and the passive matrix type semi-transmissive reflection type liquid crystal display device.

In the above embodiment, the transflective liquid crystal display device has been described as an example. However, in the cholesteric liquid crystal layer, the wavelength is equal to the spiral pitch of liquid crystal molecules and the same rotation direction as the spiral winding direction. In the case of the cholesteric liquid crystal layer that reflects all of the circularly polarized light, it functions as a reflective layer, so that a reflective liquid crystal display device can also be configured using this. In this case, the backlight (illuminator) and the lower substrate side elliptically polarized light incidence means (lower quarter wave plate 27 and lower polarization plate 28) are not required. The display principle of the reflection type liquid crystal display device is almost the same as the reflection bright display and the reflection dark display when used as a semi-transmissive reflection type.

Further, the present invention can be applied not only to the color liquid crystal display device but also to the liquid crystal display of monochrome display.
In the liquid crystal display device of the above embodiment, the semi-transmissive reflective layer 18 having a plurality of cholesteric liquid crystal layers reflects a part of white circularly polarized light in the same rotation direction as the spiral winding direction,
Although the case of having a function of transmitting a part of the liquid crystal cell 11 has been described, a reflection type color that selectively reflects color light having different wavelengths according to the spiral pitch of liquid crystal molecules in each predetermined area divided in the display area of the liquid crystal cell 11. A color liquid crystal display device can also be configured using a cholesteric liquid crystal layer having a function as a filter.

[0051]

EXAMPLE A liquid crystal display device having the structure shown in FIGS. 1 and 2 was manufactured, and the influence of the difference in the thickness and width of the metal film on the thickness of the liquid crystal layer was investigated. (Test Example 1) A liquid crystal display device having the structure shown in FIGS. The design value of the thickness of the liquid crystal layer 16 was 5 μm, and the sealing material 15 contained glass fibers having a diameter of 5 μm.
The reinforcing layer 50 was made of chromium. The width of the sealing material 15 is 1 m
The width of the reinforcing layer 50 was 1.2 mm with respect to m. The thickness of the reinforcing layer 50 is changed to 0.03 to 2.0 μm,
The thickness of the liquid crystal layer 16 was measured for each. The results are shown in Table 1 below. The thickness of the liquid crystal layer 16 was measured at the center of the region surrounded by the seal material 15 and on the diagonal line of the region surrounded by the seal material 15 and 20 times from the center.
The measurement was performed at a total of 5 points of 4 points provided at positions separated by mm, and the average value of the measured values at 5 points was obtained.

[0052]

[Table 1]

From the results shown in Table 1, the thickness of the reinforcing layer 50 was set to 0.
If the thickness is not less than 05 μm, the thickness of the liquid crystal layer 16 can be set within an error range (± 10%) (4.5 to 5.5 μm) within the allowable manufacturing error with respect to the design value of 5 μm. did it.

(Test Example 2) A liquid crystal display device having the structure shown in FIGS. The design value of the thickness of the liquid crystal layer 16 is 4μ
m, and the sealing material 15 contained glass fibers having a diameter of 4 μm. The reinforcing layer 50 is made of chrome and has a thickness of 0.
It was 1 μm. The width of the reinforcing layer 50 (described as W1 in the table) is 2.0 μm, and the width of the sealing material (described as W2 in the table) is changed in the range of 0.5 to 5.0 μm. The thickness was measured as in Test Example 1. The results are shown in Table 2 below. Table 2 shows the ratio (W1 / W1) of the reinforcing layer 50 (W1) to the width (W2) of the sealing material.
W2) is also shown.

[0055]

[Table 2]

From the results shown in Table 2, when the width of the sealing material is set to 1, and the width ratio of the reinforcing layer 50 is set to 0.8 or more, the thickness of the liquid crystal layer 16 is manufactured with respect to the design value of 4 μm. Within an error range of ± 10% which is an allowable range of error (3.6 to 4.
4 μm).

[0057]

As described above, according to the liquid crystal display device of the present invention, since the reinforcing layer is formed between the seal material constituting the liquid crystal cell and the cholesteric liquid crystal layer or the hologram layer, Even if a pressing force is applied to the sealing material toward the cholesteric liquid crystal layer or the hologram layer side, the gap material in the sealing material is prevented from slipping into the cholesteric liquid crystal layer or hologram layer side. Therefore, the thickness accuracy of the liquid crystal layer is good, and the thickness of the liquid crystal layer is uniform, so that it is possible to improve the contrast and display unevenness on the liquid crystal display screen. Also,
According to the electronic device provided with such a liquid crystal display device, the liquid crystal layer is formed to have an appropriate thickness, so that the visibility is excellent and the yield at the time of manufacturing is also good.

[Brief description of drawings]

FIG. 1 shows a schematic configuration of a liquid crystal display device according to a first embodiment of the present invention, in which (a) is a plan view and (b) is a cross section taken along line HH ′ in (a). It is a figure.

FIG. 2 is a cross-sectional view showing an enlarged main part of the liquid crystal display device of the first embodiment shown in FIG.

FIG. 3 is a diagram for explaining a display principle of the liquid crystal display device according to the first embodiment.

FIG. 4 is a plan view schematically showing a modified example of the liquid crystal display device of the first embodiment.

FIG. 5 is a plan view schematically showing another modification of the liquid crystal display device of the first embodiment.

FIG. 6 is a perspective view showing an example of an electronic device according to the present invention.

FIG. 7 is a perspective view showing another example of an electronic device according to the present invention.

FIG. 8 is a perspective view showing still another example of an electronic device according to the present invention.

[Explanation of symbols]

10 Liquid crystal display device 11 Liquid crystal cell 13 Lower substrate 14 Upper substrate 15 Seal material 15a gap material 16 Liquid crystal layer 18 Semi-transmissive reflective layer 27 Lower quarter wave plate 28 Lower polarizing plate 35 Upper 1/4 wave plate 36 Upper polarizing plate 50 Reinforcing layer 1000 Cellular phone body (electronic device) 1001, 1101, 1206 Liquid crystal display unit 1100 Watch body (electronic device) 1200 Information processing device (electronic device)

Continued front page    F-term (reference) 2H049 BA05 BA43 BB03 BC09 BC22                 2H089 LA15 LA48 MA03Y MA15Y                       QA12 QA14 QA16 RA05 SA17                       TA01 TA04 TA09 TA12 TA14                       TA15 TA17                 2H091 FA08X FA08Z FA11X FA11Z                       FA14Z FB02 FB08 FD06                       GA08 GA13 HA06 HA07 KA10                       LA02 LA12 LA17 LA18

Claims (8)

[Claims] 1. A liquid crystal display device having a liquid crystal cell in which a liquid crystal layer is sandwiched between an upper substrate and a lower substrate which are opposed to each other and are pasted together by a sealing material provided in a frame shape. A reflective layer having a cholesteric liquid crystal layer that reflects at least a part of elliptically polarized light having a predetermined rotation direction is provided on the surface of the substrate facing the liquid crystal layer, and the liquid crystal layer is elliptical from the upper substrate side. An upper substrate side elliptically polarized light incident means for making polarized light incident is provided, and the liquid crystal layer inverts the polarity of the elliptically polarized light incident in either the selective electric field applied state or the non-selective electric field applied state, and the other state. In the above liquid crystal display, the polarity is not changed, and a reinforcing layer made of a metal film or an organic film having a pencil hardness of 2H or more is provided between the reflective layer and the sealing material. Location. 2. The reflective layer is a semi-transmissive reflective layer having a cholesteric liquid crystal layer that reflects a part of elliptically polarized light having a predetermined rotation direction and transmits a part of the elliptically polarized light, and further from the lower substrate side. 2. The liquid crystal display device according to claim 1, further comprising a lower-substrate-side elliptically-polarized light incidence unit that allows elliptically-polarized light to enter. 3. A liquid crystal display device having a liquid crystal cell in which a liquid crystal layer is sandwiched between an upper substrate and a lower substrate which are opposed to each other and are pasted together by a sealing material provided in a frame shape. A reflective layer having a hologram layer is provided on the surface of the substrate facing the liquid crystal layer, and a reinforcing layer made of a metal film or an organic film having a pencil hardness of 2H or more is provided between the reflective layer and the sealing material. A liquid crystal display device characterized by the above. 4. The liquid crystal display device according to claim 1, wherein the reinforcing layer is made of a metal film selected from the group consisting of chromium, tantalum, aluminum and silver. 5. The liquid crystal display device according to claim 1, wherein the reinforcing layer has a thickness of 0.05 μm or more. 6. The ratio of the width of the reinforcing layer when the width of the sealing material is 1 in the width direction of the sealing material is 0.8 or more. The liquid crystal display device according to any one of claims. 7. The reinforcing layer is formed so as to be substantially point-symmetric with respect to the center of the region surrounded by the sealing material in a state where the sealing material is viewed in a plan view, 7. The liquid crystal display according to claim 1, wherein the reinforcing layer is present in all of the sections when the section is divided into four sections by two straight lines passing through the center and orthogonal to each other. apparatus. 8. An electronic apparatus comprising the liquid crystal display device according to claim 1.