JP2001083509A - Liquid crystal display device and electronic instrument using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semitransmissive-reflective liquid crystal display device without any double image due to parallax. SOLUTION: A semitransmissive-reflective layer 135 is arranged between a liquid crystal layer 140 and an illuminator 190. The illuminator 190 is provided with a light source 191 and a nearly transparent light transmission body 190. A light reflection means 200 is arranged on the rear side of the light transmission body 190. A light diffusing means 170 having frontal scattering characteristics is arranged between the semitransmissive-reflective layer 135 and the illuminator 190.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a reflection type display function of reflecting and displaying external light incident from the front side of a liquid crystal panel, and an illuminating device provided on the back side of the liquid crystal panel. The present invention relates to a transflective liquid crystal display device having a transmissive display function of causing light from the LCD to enter the liquid crystal panel for display.

[0002]

2. Description of the Related Art Conventionally, a reflection type display function of reflecting and displaying external light incident from the front side of a liquid crystal panel, and light from a lighting device provided on the back side of the liquid crystal panel are incident on the liquid crystal panel. As a transflective liquid crystal display device having a transmissive display function of performing display by displaying,
A transflective liquid crystal display device described in JP-A-8929 is known.

In this known transflective liquid crystal display device, when the surroundings are bright, external light incident from the front surface side of the liquid crystal panel is transflective with an opening formed in an aluminum film. Is displayed by reflecting the light. When the surroundings are dark, light from an illuminating device provided on the back side of the liquid crystal panel is passed through an opening provided on the semi-transmissive reflective film to perform transmissive display.

[0004]

However, in the transflective liquid crystal display device according to the above-mentioned prior art, a metal film having an opening as a transflective film or a thin film which is sufficiently thin to transmit light. The formed metal film is adopted. For this reason, there is a problem that light is not reflected at this opening in the case of the reflection type display, and only light transmitted through this opening is used in the case of the transmission type display, so that the light use efficiency is extremely low. .

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises a liquid crystal panel having a liquid crystal layer sandwiched between a pair of translucent substrates, and a back side of the liquid crystal panel. A semi-transmissive reflection film is provided between the liquid crystal layer and the illumination device, and the illumination device includes a light source and a substantially transparent light guide. A light reflecting means is provided on the back side of the light guide, and a light diffusing means having forward scattering characteristics is provided between the semi-transmissive reflection film and the lighting device. It is characterized by being.

According to the liquid crystal display device of the present invention, the external light that has entered the liquid crystal panel and has passed through the transflective film is reflected by the light reflecting means provided on the back side of the light guide, so that it is transflective. Since the light can be transmitted through the reflective film, the light use efficiency is remarkably improved at the time of the reflective display. However, in a liquid crystal display device in which an illuminating device or the like is arranged between the transflective film and the light reflecting means, the distance d between the liquid crystal layer and the light reflecting means is relatively large. Therefore, depending on the incident angle of the external light incident on the liquid crystal panel, the outward path of the light passing through the liquid crystal layer,
The return path is different, which causes double reflection due to parallax. In the liquid crystal display device of the present invention, this parallax is solved by the light diffusion means having forward scattering characteristics. That is, the external light that has passed through the semi-transmissive reflective film is sufficiently diffused once before passing through the light diffusing means and arriving at the light reflecting means, then reflected by the light reflecting means, and is again transmitted through the semi-transmissive reflective film. Pass through. Since the light passing through the transflective film is light that has been sufficiently diffused,
Double reflection due to parallax is reduced.

The semi-transmissive reflection film in the liquid crystal display device of the present invention is a metal film formed on the inner surface side of the liquid crystal panel and provided with an opening for transmitting light, or a thin enough to transmit light. A metal film or the like can be used. Of course, a transflective film may be provided on the outer surface side of the liquid crystal panel, but in that case, double reflection due to light reflected by the transflective film occurs due to the thickness of the substrate of the liquid crystal panel.
Preferably, a transflective film is provided on the inner surface side of the liquid crystal panel.

[0008] As the light reflecting means in the liquid crystal display device of the present invention, the higher the reflectivity, the better. Therefore, it is better to use a metal film such as aluminum or silver than a white reflector used for a general lighting device for a liquid crystal display device.

As the light diffusing means in the liquid crystal display device of the present invention, a resin having a low refractive index of 1.6 or less (polyester resin, amino resin, polyurethane resin, etc.) and fine particles having a smaller refractive index than this resin are used. (MgF2, CaF
2, LiF, NaF, BaF, or silica fine particles).

According to the liquid crystal display device of the present invention, since the external light once transmitted through the transflective film can be reused during the reflective display, a very bright reflective display is realized.
Therefore, the transmissivity of the transflective layer can be set relatively high, and the display in the transmissive display is also bright. More specifically, experiments performed by the present inventors have confirmed that a sufficiently bright reflective display can be obtained even when the light transmittance of the transflective film is 25% or more.

If the transmittance is too high, the amount of external light reflected by the semi-transmissive reflection film becomes small. Therefore, when a color display is to be performed using a color filter (described later), the vividness of the color is reduced. Have a negative effect,
The light transmittance of the transflective film is preferably 80% or less.

The inventor conducted an experiment on parallax generated due to the distance between the light reflecting means and the liquid crystal layer. In this experimental method, as shown in FIG. 7, after the display device is tilted by 30 degrees, incident light is incident on the display device from a direction inclined by 45 degrees, and the observer starts parallax from directly above. Observed, the experimental results in Table 1 were obtained. Note that the haze value H in Table 1 indicates the diffusion rate (5
９５95%), and the distance d is between the light diffusion plate 170 and the light reflection plate 2.
The distance (mm) from 00 is shown.

[0013]

[Table 1]

Horizontal axis = separation dimension d (mm) Vertical axis = haze value H (%) ：: Shadow is blurred and display is easy to understand 〇: Shadow is blurred and △: Shadow is slightly anxious ×: Shadow is clearly seen. That is, when the relationship between the haze value H at which parallax does not occur and the separation dimension d is expressed as a mathematical expression, H ≧ −200d + 14.
It becomes 0. Further, the liquid crystal display device of the present invention is characterized in that a color filter layer having a plurality of colored regions is provided above the transflective film.

The liquid crystal display device of the present invention relates to a transflective liquid crystal display device capable of color display using a color filter. In the type display, there is a problem of color mixing in addition to the double reflection described above. In other words, color mixing occurs due to the fact that the forward path and the backward path of light passing through the liquid crystal layer during the reflective display are different from each other, so that the forward path and the backward path of light pass through different colored regions. According to the present invention, external light that has passed through the color filter
After passing through the light diffusion means and arriving at the light reflection means, the light is sufficiently diffused, and after the colors are mixed, the light is reflected by the light reflection means and passes through each colored region of the color filter again. That is, the light that has been mixed once and has become a color close to white is separated again by the color filter, so that the color mixture is reduced. Regarding the position where the color filter is provided, in order to color both the light reflected by the transflective means and the light reflected by the light reflecting means on the back of the light guide, it is necessary to provide the color filter above the transflective film. is there. By the way, in order to obtain a vivid color when performing color display using a color filter, a transflective film and a color filter are provided as close as possible to each other, and a liquid crystal layer, a transflective film and a color filter are provided. It is necessary to eliminate parallax. Therefore, it is most preferable that the transflective film is provided on the liquid crystal layer side of the rear substrate of the liquid crystal panel, and the color filter is also provided on the liquid crystal layer side of the rear substrate of the liquid crystal panel.

The colored region of the present invention preferably has three colored regions of red, blue and green. By using these three colors, full colorization is possible. Furthermore, white light can be obtained by sufficiently mixing the red, blue and green colors with light diffusing means.

As the color filter, there are an optical interference filter, a hologram, a light selective reflection layer using a cholesteric liquid crystal, a retardation layer, and the like. A color filter using a dye or a pigment is most preferable because it is easy to manufacture. preferable.

Further, according to the liquid crystal display device of the present invention, a polarizing means for transmitting or absorbing incident light according to its polarization component is provided between the illumination device and the transflective film. A reflection polarization means for transmitting or reflecting incident light according to the polarization component is provided between the polarization means and the illumination device, and the transmission axis directions of the polarization means and the reflection polarization means are substantially parallel. It is characterized by.

Generally, a TN (twisted nematic) type liquid crystal panel, a STN (super-twisted nematic) type liquid crystal panel, or an ECB (electorically controlled bi
When performing transmissive display using a transflective liquid crystal display device using an efringence type liquid crystal panel, etc., it is necessary to align the polarization of the light from the lighting device before entering the liquid crystal panel. Required. Conventional technology (JP-A-7-3
Japanese Patent No. 18929) uses a polarizing plate that absorbs and transmits light in accordance with a polarized light component, thereby aligning the polarization of light from the lighting device. However, when this polarizing plate is used, more than half of the light from the lighting device is absorbed by the polarizing plate, so that the use efficiency of light (of the lighting device) is low, and particularly, the transmission type display is darkened. Had been lost.

According to the liquid crystal display device of the present invention, of the light emitted from the illumination device, only light having a polarization component equal to the transmission axis direction of the polarizing means and the reflective polarizing means passes through the polarizing means and the reflective polarizing means, and Illuminate the panel. On the other hand,
Light having a different polarization component is reflected by the reflection polarization means. Then, the light is reflected by the light reflecting means and again enters the reflection polarizing means. Then, as the reflection between the reflection polarization means and the light reflection means is repeated, the polarization direction changes, and eventually the light passes through the polarization means and the reflection polarization means. for that reason,
Light from the lighting device can be effectively used without being absorbed by the polarizing plate.

As the reflection polarizing means in the present invention, for example, a reflection polarizer having the structure shown in FIG. 1 can be used. The reflective polarizer 160 has a structure in which two different layers 1 (A layer) and 2 (B layer) are alternately laminated in a plurality of layers. The refractive index (nAX) in the X direction of the A layer 1 is different from the refractive index (nAY) in the Y direction. Refractive index of the B layer 2 in the X direction (nBX)
And the refractive index (nBY) in the Y direction are equal. Further, the refractive index (nAY) of the A layer 1 in the Y direction and the refractive index (n
BY).

Therefore, the upper surface 5 of the reflection polarizing means 160
Out of the light incident on the reflective polarizer 160 from a direction perpendicular to the reflective polarizer 160, the linearly polarized light in the Y direction is transmitted through the reflective polarizer 160 and emitted from the lower surface 6 as linearly polarized light in the Y direction. Conversely, among the light incident on the reflective polarizer 160 from a direction perpendicular to the lower surface 6 of the reflective polarizer 160, linearly polarized light in the Y direction is transmitted through the reflective polarizer 160 and linearly polarized in the Y direction from the upper surface 5. Out. Here, the transmission direction Y is referred to as a transmission axis.

On the other hand, the thickness of the A layer 1 in the Z direction is t
When the thickness of the A and B layers 2 in the Z direction is tB and the wavelength of the incident light is λ, tA · nAX + tB · nBX = λ / 2 (1) The reflective polarizer 1 is arranged in a direction perpendicular to the upper surface 5 of the reflective polarizer 160.
The linearly polarized light in the X direction out of the light incident on 60 is reflected by this reflective polarizer 160 as linearly polarized light in the X direction. Further, the light having the wavelength λ and the reflection polarizer 16
The linearly polarized light is reflected by the reflective polarizer 160 as linearly polarized light in the X direction on the lower surface 6 of the zero. Here, the direction of reflection X is referred to as a reflection axis.

The thickness tA of the A layer 1 in the Z direction
By varying the thickness tB of the B layer 2 in the Z direction so that the above (1) is satisfied over the entire wavelength range of visible light, a straight line in the X direction can be obtained not only for a single color but also for all white light. A reflection polarizer that reflects the polarized light as linearly polarized light in the X direction and transmits the linearly polarized light in the Y direction as linearly polarized light in the Y direction is obtained. Such a reflective polarizer is disclosed in International Publication WO 95/17 (WO 95/17).
692). Note that an element having a structure in which a cholesteric liquid crystal layer is sandwiched between λ / 4 plates also has a reflective polarization function.

The liquid crystal display device according to the present invention is characterized in that the light guide is substantially isotropic.

When the light guide has a large optical anisotropy,
The display appearance may be colored and color unevenness may occur. Therefore, if the light guide is optically close to isotropic, the display appearance will not be colored or color unevenness will occur, and the display will be bright.

Further, the light guide has optical anisotropy, and has regularity in the optical axis direction of the light guide. When the optical axis direction has a certain direction, that is, regularity such as uniaxiality or biaxiality, color unevenness can be prevented from occurring.

Further, an electronic apparatus according to the present invention is characterized in that the liquid crystal display device having any one of the above structures is mounted as a display unit.

Next, the display principle of the liquid crystal display device of the present invention will be described in detail with reference to FIGS. FIG. 2 is a diagram for explaining a case where external light is incident on a display device using the reflection polarizing means, and FIG. 3 is a diagram for explaining a case where a light source is turned on.

FIG. 2 is a diagram for explaining a case where external light is incident on a display device using the reflection polarizing means 160. In this display device, a retardation plate 131 and a polarizing plate 130 are provided above the TN liquid crystal 140. Below the TN liquid crystal 140, a color filter 145 of three colors of red, green and blue, a light transflective film 135, a λ / 4 retardation plate 151, a polarizing plate 150, and a reflective polarizing means 160 are provided in this order. ing. Also, below the reflective polarizing means 160, there is a light guide 190 capable of emitting light from the light source 191 from below the reflective polarizing means 160, and a reflecting plate 200.
Are provided. The semi-transmissive reflective film 135 is a metal film containing aluminum or silver and is made of a thin film or a metal film with a hole formed in a part thereof. The semi-transmissive reflective film 135 reflects some light and transmits the rest of the light. It is.

Referring to FIG. 2, the left side of the display device under external light is a voltage application section 110, and the right side is a voltage non-application section 12
Description will be made assuming 0. In the voltage application section 120 on the right side, the natural light 121 is converted into linearly polarized light in a direction parallel to the plane of the drawing by the polarizing plate 130, and then passes through the phase difference plate 131 and the TN liquid crystal 140 to become linearly polarized light. At 135, some light is reflected and the rest is transmitted. A part of the reflected light passes through the TN liquid crystal 140 and the phase difference plate 131 again, becomes linearly polarized light in a direction parallel to the paper surface, and exits the polarizing plate 130. Further, the remaining part of the transmitted light is diffused by the light diffusion plate 170 having forward scattering characteristics, then becomes circularly polarized light by the λ / 4 retardation plate 151, becomes linearly polarized light by the polarizing plate 150, and becomes a reflected polarizing means 160. Is transmitted as linearly polarized light in a direction parallel to the paper surface, passes through the transparent light guide 190, and is reflected by the reflector 200. The light guide 1 is provided between the light diffusion plate 170 and the reflection plate 200.
90, reflective polarizer, λ / 4 retarder 151, polarizer 15
Since a sufficient distance is provided by 0 or the like, the light is reflected by the reflection plate 200 in a sufficiently diffused state, and is again reflected by the light guide 190, the reflection polarization means 160, and the polarization plate 150.
, And becomes circularly polarized light by the λ / 4 phase difference plate 151, passes through the transflective film 135, the TN liquid crystal 140, and the phase difference plate 131 as circularly polarized light, and a part of the light becomes linearly polarized light by the polarizing plate 130. Emit. Therefore, the light passes through the color filter 145 and is colored. In FIG. 1, the light diffusing plate is a semi-transmissive reflecting plate and a λ / 4 retardation plate 1.
However, when the light guide 190 is relatively thicker than the reflective polarizing plate, the λ / 4 retardation plate 151, the polarizing plate 150, etc., the light diffusing plate is a semi-transmissive reflecting plate. It may be arranged at any position between the reflector and the reflector.

The light reflected by the reflector includes not only linearly polarized light in a direction parallel to the plane of the paper but also linearly polarized light in a direction perpendicular to the plane of the paper. Such linearly polarized light in the direction perpendicular to the plane of the paper is reflected by the reflective polarizing means 160, reflected again by the reflection plate 200, the polarization direction is changed, and becomes partially polarized light in a direction parallel to the plane of the paper. pass. By repeating this, light can be used effectively and the image becomes brighter. Thus, when no voltage is applied,
Since the incident light can be effectively used by the reflection polarizing means 160, a bright display can be obtained. Further, the transflective film 13
Since the light reflected at 5 is also used, there is no shadow and the image becomes colorful.

In the voltage application section 110 on the left side, the natural light 111 is converted into linearly polarized light in a direction parallel to the paper surface by the polarizing plate 130, and thereafter, the phase difference plate 131 and the TN liquid crystal 1
After passing through 40, the light becomes circularly polarized light, and the transflective film 135
Some light is reflected as circularly polarized light in the opposite direction of rotation,
The remaining part of the light is transmitted. Part of the reflected light passes through the TN liquid crystal 140 and the phase difference plate 131 again, becomes linearly polarized light in a direction perpendicular to the paper surface, and is absorbed by the polarizing plate 130. In addition, the remaining light that has passed through is converted to a λ / 4 retardation plate 151.
As a result, linearly polarized light in a direction perpendicular to the plane of
Absorbed by 50. That is, it becomes dark. As described above, in the voltage non-applying section 120, the reflection polarizing means 1
60, the reflected light becomes the emission light 122 colored by the color filter 145. In the voltage application unit 110, the polarizing plate 130 and the polarizing plate 150 are used.
It becomes absorbed and darkened.

Next, referring to FIG. 3, the display device comprises:
It is the same as FIG.

When the light source 191 is turned on, the light 125 from the lighting device is
Of the linearly polarized light in a direction parallel to the paper
60 is transmitted. In addition, the linearly polarized light in the direction perpendicular to the paper of the light 125 of the light source is reflected by the reflective polarizing means 160, reflected again by the reflection plate 200, the polarization direction is changed, and becomes partially polarized light in a direction parallel to the paper. , Pass through the reflective polarizing means 160. By repeating this, almost all the light passes through the reflective polarizing means 160. The linearly polarized light in the direction parallel to the paper surface that has passed through the reflective polarizing means 160 and passed through the polarizing plate 150 is converted into circularly polarized light by the λ / 4 retardation plate 151, passes through the semi-transmissive reflective film 135, and is colored by the color filter 145. TN liquid crystal 140, retardation plate 1
Due to 31, the light remains circularly polarized, and part of the light is emitted from the polarizing plate 130. That is, the light can be effectively used by the reflection polarizing means 160, and the light becomes very bright.

In the voltage application section 110 on the left side, the linearly polarized light in the direction parallel to the paper of the light 115 of the light source passes through the reflective polarization means 160. The linearly polarized light in the direction parallel to the paper surface that has passed through the reflective polarizing means 160 and passed through the polarizing plate 150 is converted into circularly polarized light by the λ / 4 retardation plate 151, passes through the semi-transmissive reflective film 135, and is colored by the color filter 145. Then, the TN liquid crystal 140 and the retardation plate 131 convert the light into linearly polarized light in a direction perpendicular to the plane of the paper, and the light is absorbed by the polarizing plate 130 and becomes dark.

As described above, in the voltage non-applying section 120, the light is colored by the color filter 145, the light can be effectively used by the reflective polarizing means 160, and the light becomes very bright.
In the voltage applying unit 110, the light is absorbed by the polarizing plate 130 and becomes dark. Therefore, if the light source color is white while the light source 191 is on, switching between coloring of the color filter 145 and black display can be obtained.

Here, the color filters 145 are red, green,
If the dot matrix display is blue, multi-color display and even full-color display can be performed. Although the normally white mode has been described above, normally black may be used. However, in the normally white mode, the effect of being bright both in reflection and in transmission is clearly exhibited. In the above, T
Although the description has been made by taking the N liquid crystal 140 as an example, the TN liquid crystal 140
The basic operation principle is the same even if another transmission polarization axis such as an STN liquid crystal can be changed by a voltage or the like instead of the above.

[0039]

Embodiments of the present invention will now be described with reference to the drawings.

(First Embodiment) FIG. 4 is an exploded sectional view for explaining a display device according to a first embodiment of the present invention.

In the display device 10 of the present embodiment, S
On the upper side of the TN liquid crystal panel 20, a diffusion adhesive layer 14 having a light diffusion function, that is, a forward scattering function, a first retardation film 13, a second retardation film 12, and a polarizing plate 11 are provided in this order. On the lower side of the STN liquid crystal panel 20, a diffusion adhesive layer 17 having a forward scattering function, a λ / 4 retardation film 15, a polarizing plate 16, and a reflective polarizing means 40 are provided in this order. The diffusion adhesive layer 17 has a haze (H) value of 82%. Further, an illumination device 70 to which light can enter from below the reflection polarizing means 40 is provided. The lighting device 70 uses an LED (Light Emitting Diode) 71 as a light emitter, and emits light upward through a light guide 72. A reflection plate 80 is provided below the light guide 72. As the transparent material forming the light guide 72, a transparent resin such as an acrylic resin, a polycarbonate resin, or an amorphous polyolefin resin, an inorganic transparent material such as glass, or a composite thereof is preferably used. The thickness is 0.3 to 2 mm. The surface has small protrusions. The size of the protrusion is about 5 μm or more in order that the wavelength of visible light is about 380 nm to about 700 nm, so that the influence of diffraction does not occur, and the size of the protrusion is such that the protrusion is not noticeable to the naked eye. It is desirable that the size be approximately 300 μm or less. Further, in consideration of manufacturing convenience, the size of the projection is preferably about 10 μm or more and 100 μm or less. The ratio between the height and the width of the protrusion (the diameter if it is substantially a column) may be 1: 1 or less. In this embodiment, the shape of the projection is 20 μm in diameter,
A column having a height of 15 μm was formed, and the pitch was set to 20 μm.

As the reflection plate 80, a film obtained by evaporating aluminum or silver on a PET film, an aluminum foil or the like is used.
The shape of the surface of the reflection plate 80 may be a mirror surface or a scattering surface. In the STN liquid crystal panel 20, an STN liquid crystal 26 is sealed in a cell constituted by two glass substrates 21, 22 and a sealing member 23. Glass substrate 2
1, a transparent electrode 24 is provided on the lower surface of the glass substrate 22.
Is provided with a transparent electrode 25 on the upper surface thereof to form a dot matrix. As the transparent electrodes 24 and 25, ITO (Indium Tin Oxide), tin oxide, or the like can be used. Further, a red / green / blue color filter 27 is formed between the transparent electrode 24 and the glass substrate 21 and matches the electrode pattern of the transparent electrode 25. Further, on the upper surface of the glass substrate 22, on the lower surface of the transparent electrode 25, an aluminum vapor-deposited layer 28 is formed in a line shape as a transflective film, and the aluminum vapor-deposited layer 28 has a slit-like hole. Thereby, the aluminum deposition layer 28 has both the reflection function and the transmission function.

By applying or not applying a voltage to the STN liquid crystal 26, the light polarization state in the aluminum vapor deposition layer 28 changes and the first
Retardation film 13 and second retardation film 12
Are set so as to obtain a circularly polarized state and a linearly polarized state. The λ / 4 retardation film 15 changes the light from the light guide 72 into circularly polarized light. The reflection polarizer described with reference to FIG. 1 is used as the reflection polarization means 40 in the present embodiment. Further, the reflection polarizing means 40
And the direction of the transmission axis of the polarizing plate 16 match.

Next, the operation of the display device 10 according to the present embodiment will be described. Under the external light, in the voltage non-applied region, natural light is converted into linearly polarized light in a predetermined direction by the polarizing plate 11, and thereafter, by the second retardation film 12, the first retardation film 13, and the STN liquid crystal panel 20. The polarization direction becomes linearly polarized light having a predetermined angle twisted, and the aluminum deposition layer 2
At 8, some are reflected and some are transmitted. The reflected light passes through the STN liquid crystal panel 20, the first retardation film 13, the second retardation film 12, and the polarizing plate 11 again, and becomes brighter. On the other hand, the transmitted light is converted into circularly polarized light by the λ / 4 retardation film 15, and a part of the light passes through the polarizing plate 16 and the reflection polarizing means 40. The transmitted light passes through the light guide 72, is reflected by the reflector 80, passes through the light guide 72, the reflection polarizing means 40, and the polarizing plate 16 again, and becomes circularly polarized by the λ / 4 retardation film 15. , STN liquid crystal panel 20, first retardation film 13, second retardation film 12,
Further, the light passes through the polarizing plate 11 and becomes bright. Further, the light whose polarization direction has been changed by the reflection plate 80 is repeatedly reflected between the reflection polarization means 40 and the reflection plate 80, and eventually the reflection polarization means 40.
Then, light is emitted to the STN liquid crystal panel 20, a bright display is obtained, and light is used effectively. At that time, color filter 2
When light passes through 7, the color of any of red, green, and blue is exhibited. In addition, since the diffusion adhesive layer 14 is provided, the reflected light is scattered and a bright display with a wide viewing angle is obtained.

In the voltage application region, natural light is converted into linearly polarized light in a predetermined direction by the polarizing plate 11, and thereafter,
Second retardation film 12, first retardation film 1
3. The polarization direction is circularly polarized by the STN liquid crystal panel 20, and the aluminum vapor deposition layer 28 partially reflects and partially transmits. The reflected light becomes reverse circularly polarized light, and when it passes through the STN liquid crystal panel 20, the first retardation film 13, and the second retardation film 12 again, it becomes linearly polarized light.
It is absorbed by 1 and darkens. On the other hand, the transmitted light is λ
The light is converted to linearly polarized light by the / 4 retardation film 15 and absorbed by the polarizing plate 16 to become dark.

Next, when the lighting device 70 is turned on, in the no-voltage application region, the light emitted from the lighting device 70 passes through the reflective polarizing means 40 and the polarizing plate 16 and is circularly polarized by the λ / 4 retardation film 15. And the STN liquid crystal panel 20,
First retardation film 13, second retardation film 1
2. The light further passes through the polarizing plate 11 and becomes bright. Further, the light emitted from the illumination device 70 is effectively used by the reflection polarizing means 40, and a bright display is obtained. At this time, if light passes through the color filter 27, the color filter 27 exhibits any of red, green, and blue.

In the voltage application region, the light emitted from the illumination device 70 passes through the reflection polarizing means 40 and the polarizing plate 16 and is converted into circularly polarized light by the λ / 4 retardation film 15.
The STN liquid crystal panel 20, the first retardation film 13, and the second retardation film 12 form linearly polarized light in a predetermined direction, and are absorbed by the polarizing plate 12. That is, it becomes dark. In other words, red, green, and
A bright color display can be obtained by the blue color filter. Here, when examining the optical anisotropy in the plane of the light guide 72, color unevenness occurs at a place having anisotropy of 400 nm or more, and conversely, at a place having anisotropy of 150 nm or less. There was no problem with color unevenness. Therefore, the in-plane optical anisotropy of the light guide is preferably set to 400 nm or less, and more preferably 150 nm or less.

(Second Embodiment) FIG. 5 is a schematic diagram for explaining a liquid crystal display device according to a second embodiment of the present invention. That is, in the first embodiment, the surface of the glass substrate 22 is roughened, and the aluminum deposition layer 28 is provided thereon. The surface of the glass substrate 22 may be roughened by directly exposing the substrate surface, or by providing a film and performing embossing or etching. Thereby, the aluminum deposition layer 2
Since the diffusion effect is obtained in 8, the diffusion adhesive layer 14 becomes unnecessary. Further, by roughening the surface of the glass substrate 22, a forward scattering characteristic is obtained, and the diffusion adhesive layer 17 becomes unnecessary. As a result, a result similar to that of the first embodiment was obtained. Furthermore,
In the first embodiment, the display is blurred.
In the embodiment, no blurring of the display is seen, and the display is easy to see.

(Third Embodiment) In the second embodiment, a circular polarizing plate made of a cholesteric liquid crystal or the like is used as the reflective polarizing means 40 instead of the reflective polarizing means described with reference to FIG. And a λ / 4 plate were substituted. The same effect as in the first embodiment was obtained.

(Fourth Embodiment) FIG. 6 is a schematic diagram for explaining a liquid crystal display device according to a fourth embodiment of the present invention. That is, in the first embodiment, the color filter 27 is placed on the glass substrate 2 from the inside of the glass substrate 21.
2 was formed inside. The same effect as in the first embodiment was obtained.

(Fifth Embodiment) In the second embodiment, the transmittance of the aluminum vapor-deposited layer is changed by changing the size of the slit-shaped holes in the aluminum vapor-deposited layer 28 in various ways. Therefore, display is performed and the reflectance at the time of reflection, the color gamut area,
The transmittance at the time of transmission was measured. The color gamut area refers to the area of a triangle formed by connecting the respective x and y coordinates on a CIE chromaticity diagram shown by red, green and blue display with straight lines.
The results are shown in Table 2.

[0052]

[Table 2]

As described above, the transmittance of the aluminum deposition layer is 25
A good balance between the reflectance at the time of display, the color gamut area, and the transmittance at the time of transmission is between -80%. The range of 40 to 70% is more preferable.

(Sixth Embodiment) A display device according to a first embodiment of the present invention is mounted on an information terminal. Bright displays were obtained in the sun, in the shade, indoors and at night.

Similar results were obtained with information terminals equipped with the display devices according to the second to eighth embodiments of the present invention.
Although the information terminal is exemplified in the embodiment of the present invention, the display device of the present invention can be used for various electronic devices such as a mobile phone, a PDA, a home appliance, an electronic organizer, and a calculator.

[0056]

According to the present invention, the external light incident on the liquid crystal panel and transmitted through the transflective film is reflected by the light reflecting means provided on the back side of the light guide, so that the transflective film is formed. Can be transmitted, so that the use efficiency of light at the time of reflection type display is remarkably improved. Further, since the distance d between the liquid crystal layer and the light reflecting means is relatively large, the external light passing through the semi-transmissive reflecting film once passes through the light diffusing means and reaches the light reflecting means. After being sufficiently diffused, the light is reflected by the light reflection means and passes through the semi-transmissive reflection film again, so that double reflection due to parallax is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a reflective polarizing means used in a display device of the present invention.

FIG. 2 is a diagram for explaining the principle of reflection of the display device of the present invention.

FIG. 3 is a diagram for explaining the principle of transmission of the display device of the present invention.

FIG. 4 is an exploded cross-sectional view for explaining the display device according to the first embodiment of the present invention.

FIG. 5 is an exploded cross-sectional view illustrating a display device according to a second embodiment of the present invention.

FIG. 6 is an exploded cross-sectional view illustrating a display device according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing an experimental method for parallax.

[Explanation of symbols]

 Reference Signs List 10 display device 11, 16, 130, 150 polarizing plate 12 second retardation film 13 first retardation film 14 diffusion adhesive layer 17 diffusion adhesive layer 20 STN liquid crystal panel 21 , 22: Glass substrate 26: STN liquid crystal 27, 145: Color filter 28: Aluminum vapor-deposited layer 15, 151: λ / 4 phase difference plate 40, 160: Reflective polarizing means 70, 191: Illumination device 72, 190: Light guide 80, 200: Reflecting plate 110: Voltage applying unit 120: No voltage applying unit 111, 121: Natural light 122: Emitted light 115, 125: Light of light source 131: Phase difference plate 135: Semi-transmissive reflective film 140: TN liquid crystal 170 Light diffusion means

Claims (7)

[Claims] 1. A liquid crystal display device comprising: a liquid crystal panel having a liquid crystal layer sandwiched between a pair of translucent substrates; and a lighting device disposed on the back side of the liquid crystal panel. A semi-transmissive reflection film is provided between the light guide and the device, the lighting device includes a light source and a substantially transparent light guide, and a light reflection unit is provided on a back side of the light guide. A light diffusion means having forward scattering characteristics is provided between the transflective film and the lighting device. 2. The liquid crystal display device according to claim 1, wherein a distance between the light diffusing unit and the light reflecting unit is d (m
m), the haze value H (%) of the light diffusion means
Satisfies the relationship of H ≧ −200d + 140. 3. The liquid crystal display device according to claim 1, wherein a color filter layer having a plurality of colored regions is provided above the transflective film. Liquid crystal display device. 4. The liquid crystal display device according to claim 1, wherein between the illuminating device and the transflective film, incident light is transmitted or absorbed according to its polarization component. Polarizing means is provided, and between the polarizing means and the lighting device, there is provided a reflective polarizing means for transmitting or reflecting incident light according to the polarization component thereof, and transmission of the polarizing means and the reflective polarizing means is provided. A liquid crystal display device wherein the axial directions are substantially parallel. 5. The liquid crystal display device according to claim 1, wherein the light guide is substantially isotropic. 6. The liquid crystal display device according to claim 1, wherein the light guide has optical anisotropy, and an optical axis direction of the light guide has regularity. A liquid crystal display device comprising: 7. An electronic apparatus comprising the liquid crystal display device according to claim 1 as a display unit.