JP4571423B2 - Liquid crystal device - Google Patents

Description

The present invention relates to a liquid crystal device provided with a light guide member, and more particularly to a liquid crystal device capable of illuminating a liquid crystal device provided with one light guide member on both upper and lower surfaces.

Recently, many mobile phones have liquid crystal panels provided on the top and bottom of the upper lid.
A liquid crystal panel for a telephone needs to be provided with a backlight so that the display can be recognized even in a dark place. However, a telephone with two such liquid crystal panels requires two sets of backlights. There was a problem that would become thick.
Therefore, a liquid crystal device of the type as shown in FIG. 10 has begun to be used.
In FIG. 10, a main liquid crystal panel 100 having a relatively large display area and a sub liquid crystal panel 104 having a relatively small display area are provided above and below one light guide member 102. Is emitted by emitting light in both the upper and lower directions through the light guide member 102.
With this configuration, it is possible to illuminate the two liquid crystal panels 100 and 104 only by providing one light guide member 102, so that there is a remarkable effect in reducing the thickness of the telephone. However, since the light is emitted up and down, half of the light is wasted and when the sub liquid crystal panel 104 is illuminated, the light emitted to the area b shown in the figure works effectively as illumination light for the display device. However, there is a problem that the light emitted to the region a shown in the figure is wasted and the illumination efficiency is poor.

There is a light scattering type liquid crystal as a technology candidate for solving such a problem.
The light scattering liquid crystal panel travels light straight in a region where a voltage is applied, and scatters light in a region where a voltage is not applied. There is a proposal to use a light-scattering liquid crystal panel as a display panel using this characteristic, and to scatter light only in a voltage non-application region by introducing light into the panel (see, for example, Patent Document 1).
However, it is impossible to use a light-scattering type liquid crystal panel in a high-definition liquid crystal panel that requires high contrast, and a technique for illuminating two liquid crystal panels with one light source and a light guide member, which is an object of the present invention. There is no suggestion in Patent Document 1 regarding this.

Proposals have been made to further improve the optical characteristics of the light-scattering liquid crystal panel using the same technique as in Patent Document 1 (see Patent Documents 2 and 3).
However, like the proposal of Patent Document 1, it is impossible to use a light scattering liquid crystal panel for a high-definition liquid crystal panel that requires a high contrast ratio, and one light source and a light guide member that are the objects of the present invention. There is no suggestion about the technology to illuminate the two liquid crystal panels.

Further, a proposal has been made to use a light scattering type liquid crystal panel as a light guide member (see, for example, Patent Document 4 and paragraphs 0213 and after).
However, since the technique of Patent Document 4 is based on the premise that light is extracted from one side and that it is premised on scanning the backlight region, it relates to a technique that eliminates the poor illumination efficiency described with reference to FIG. There is no suggestion.

JP-A-10-206848 Patent No. 3479493 Japanese Patent No. 3478784 JP 2002-236290 A

The problem to be solved is that the upper and lower two liquid crystal panels could not be efficiently illuminated with one light source and a light guide member.

The present invention has two liquid crystal panels to be laminated, it is arranged between the two liquid crystal panels, and the light guide member for illuminating these liquid crystal panel and a light source disposed on the side of the light guide member in the liquid crystal device, the light guide member, a first surface and a second surface facing the respective light emitting surface, it has become a controllable light scattering type liquid crystal panel by electrical means the size of the scattering region It is characterized by.

  The liquid crystal device according to the present invention is characterized in that, in claim 1, the light scattering type liquid crystal panel is a polymer dispersion type liquid crystal panel.

The liquid crystal device according to the invention, the light guide member is characterized in that the size of the light emitting region of the first face and the second opposing surfaces are different.

The liquid crystal device according to the invention, the provided liquid crystal panel is disposed, respectively so as to face the first surface and the second surface of the light guide member, the liquid crystal panel is a liquid crystal panel having a different display area It is characterized by that.

  The liquid crystal device according to the present invention is the liquid crystal panel according to any one of claims 1 to 5, wherein the liquid crystal panels respectively disposed opposite to the first surface and the second surface of the light guide member have different sizes. The light emitting area of the first surface of the light guide member is substantially equal to the size of the display area of the liquid crystal panel disposed opposite to the first surface, and The light emitting area of the second surface of the optical member is set to be approximately equal to the size of the display area of the liquid crystal panel disposed to face the second surface.

  The liquid crystal device according to the present invention is a liquid crystal device having a liquid crystal panel, a light guide member that illuminates the liquid crystal panel, and a light source disposed on a side of the light guide member. Each of the first surface and the second surface is made of a light scattering type liquid crystal panel whose light emitting surface can be controlled by electric means, and is opposed to the first surface and the second surface of the light guide member. Each of the liquid crystal panels is composed of a main liquid crystal panel having a relatively large display area and a sub liquid crystal panel having a relatively small display area. When the main liquid crystal panel is driven, control is performed so that the display area of the main liquid crystal panel is approximately equal to the display area. When the sub liquid crystal panel is driven, the display area of the sub liquid crystal panel is controlled. Size and Characterized by being controlled to substantially equal.

The liquid crystal device according to the present invention is characterized in that, in claim 7, the light scattering type liquid crystal panel is a polymer dispersion type liquid crystal panel.

  The liquid crystal device according to the present invention is characterized in that, in any one of claims 1 to 8, a transflective plate is provided between the light guide member and one of the liquid crystal panels.

The liquid crystal device according to the invention, in any one of claims 1 8, characterized in that a polarization separation sheet between the guide member and the liquid crystal panel.

  The liquid crystal device according to the present invention is characterized in that, in claim 7 or 8, a reflecting plate is provided in a portion other than the display area of the sub liquid crystal panel on the surface of the light guide member on the sub liquid crystal panel side.

The liquid crystal device according to the invention, in any one of claims 1 8, wherein the light guide member is to hold the light-scattering-type liquid crystal material by two opposing transparent substrate, the light of the light source is the A polarization separation sheet is provided between one of the transparent substrates that are incident on one of the transparent substrates facing the light guide member, and the other transparent substrate among the transparent substrates facing the light guide member. To do.

The liquid crystal device according to the present invention, in claim 7 or 8, opposite of the light guide member is to hold the light-scattering-type liquid crystal material with a transparent substrate of the two opposing light of the light source light guide member The transparent substrate is incident on one of the transparent substrates, and a polarization separation sheet is provided between the other transparent substrate of the transparent substrates facing the light guide member and one of the liquid crystal panels, and the light from the light source is incident on the transparent substrate. The sub liquid crystal panel is placed on the transparent substrate side of the light guide member, and a reflector is provided on a portion of the light guide member on the sub liquid crystal panel side other than the display area of the sub liquid crystal panel. .

According to the present invention, a liquid crystal device having liquid crystal panels on both sides back to back can be efficiently illuminated with one light source and a light guide member, and a reduction in thickness and a reduction in power consumption can be realized.

  In a liquid crystal device having a liquid crystal panel, a light guide member that illuminates the liquid crystal panel, and a light source disposed on a side of the light guide member, the light guide member is opposed to a first surface and a second surface. Are made of a light scattering type liquid crystal panel in which the light emission area can be controlled by electric means.

In addition, a liquid crystal panel is disposed to face the first surface and the second surface of the light guide member, respectively, and each of the liquid crystal panels includes a main liquid crystal panel having a relatively large display area and a display area. The light scattering region of the light guide member is controlled to be approximately equal to the size of the display region of the main liquid crystal panel when the main liquid crystal panel is driven. When the sub liquid crystal panel is being driven, control is performed so as to be approximately equal to the size of the display area of the sub liquid crystal panel.

2, 3 and 4 are diagrams for explaining the present invention, and FIG. 1 is a diagram showing a first embodiment of the present invention.
2A is a plan view of a lighting device used in the liquid crystal device of the present invention, and FIGS. 2B, 2C, and 2D are cross-sectional views taken along line AA ′ of FIG.
The lighting device of FIG. 2 is composed of a polymer dispersion type liquid crystal panel which is a light scattering type liquid crystal panel, and 10 is a lower transparent substrate which is one transparent substrate. Reference numeral 16 denotes a light source, and separated transparent electrodes 12 and 14 are formed on the lower transparent substrate 10. The outer diameter of the transparent electrode 12 is approximately equal to the display area of the main liquid crystal panel described later, and the outer diameter of the transparent electrode 14 is set approximately equal to the display area of the sub liquid crystal panel described later.

2B, reference numeral 24 denotes an upper transparent substrate of the light scattering type liquid crystal panel constituting the light guide member 56, 10 denotes a lower transparent substrate, and 32 denotes almost the entire area of the upper transparent substrate 24 as shown in FIG. 2 and 14 are provided on the lower transparent substrate 10, respectively. The lower transparent electrode having the shape shown in FIG. 2A, and 26 is the upper transparent electrode. A polymer dispersed liquid crystal which is a light scattering liquid crystal in a region surrounded by the transparent substrate 24 and the transparent substrate 10 seal portion 26 in a seal portion where a seal member for bonding the transparent substrate 24 and the lower transparent substrate 10 is disposed. A light scattering liquid crystal layer 30 made of a material is sandwiched. Reference numeral 22 denotes an upper prism sheet and a 28 lower prism sheet, which function to condense light emitted from the light guide member in a desired direction. Reference numeral 20 denotes a light source for making light incident on the light guide member 56, which is an LED. Reference numeral 18 denotes a reflector. The upper surface of the light guide member 56 in FIG. 2B is a first surface, and the lower surface is a second surface.
2B, 2C, and 2D show the difference in the state of the light scattering liquid crystal layer (hereinafter also referred to as a liquid crystal layer) 30, and the change in the state of the light scattering liquid crystal layer 30 in each figure. FIG. 2B shows a state in which light is transmitted through the liquid crystal layer. Such a state occurs when a voltage is applied across the upper transparent electrode 32 and the lower transparent electrodes 12 and 14. . FIG. 2C shows a state in which light is scattered throughout the liquid crystal layer. Such a state occurs when no voltage is applied between the upper transparent electrode 32 and the lower transparent electrodes 12 and 14. FIG. 2D shows a state in which light is scattered on the lower transparent electrode 14 and light is transmitted through the lower transparent electrode 12. Such a state is a voltage between the upper transparent electrode 32 and the lower transparent electrode 12. Occurs when no voltage is applied between the upper transparent electrode 32 and the lower transparent electrode 14.
As shown in the figure, the state in which the liquid crystal layer 30 transmits light is indicated by fine dots, and the state in which light is scattered is indicated by a dark dot pattern.
The details of the light scattering type liquid crystal panel are described in detail in Patent Documents 1, 2, 3, and 4 described above.
In the following drawings, the same members are denoted by the same reference numerals and indicated by the same oblique lines or patterns.

FIG. 3 is a diagram showing the behavior of light passing through the light guide member. 34 shows a display area of the main liquid crystal panel for display provided on the upper side of the light guide member 56, and 36 is under the light guide member 56. 2 shows a display area of a display sub-liquid crystal panel provided on the side.
FIG. 3A is a diagram when the liquid crystal layer 30 is in a state of scattering light over the entire area, and the light emitted from the light source 20 is an air layer between the transparent substrates 24 and 10 and the liquid crystal panels (34 and 36). The light is totally reflected at the upper and lower boundaries in contact with the liquid crystal, but travels in the liquid crystal layer 30 having a refractive index close to that of the liquid crystal layer 30 and is scattered in the liquid crystal layer 30. At this time, the light is mainly scattered in the traveling direction of the light. Accordingly, the light traveling in the upper transparent substrate 24 is emitted mainly to the lower side, and the light traveling in the lower transparent substrate 10 is mainly scattered upward. Since the light source 20 is disposed between the upper transparent substrate 24 and the lower transparent substrate 10, approximately 50% of the light emitted from the light source 20 illuminates the main liquid crystal panel 34 and serves as backlight light.

FIG. 3B shows an example in which a light-shielding reflecting plate 38 is provided, and the light emission area below the light guide member 56 is limited by the function of the light-shielding reflecting plate 38. That is, the lights 40 and 42 that go out of the sub liquid crystal panel in FIG. 3A become weak reflected lights 44 and 46 by the light-shielding reflecting plate 38 in FIG. 3B. If the reflectance of the light-shielding reflecting plate 38 is set to the same level as the light reflectance when the sub liquid crystal panel 36 is in the display OFF state, the shadow of the light-shielding reflecting plate 38 is not projected on the main liquid crystal panel 34.
If the light-shielding reflecting plate 38 is provided in this way, the light emitting area of the upper first surface facing the light guide member 56 is c as shown, and the light emitting area of the lower second surface is d as shown. Thus, the light emission area can be made different between the first surface and the second surface.

FIG. 3C is a view when only the region of the transparent electrode 14 in FIG. 2A is in a state of scattering light as shown in FIG. 2D, and the light emitted from the light source 20 is transparent substrate. The light is totally reflected at the upper and lower boundaries in contact with the air layers 20 and 10, but proceeds into the liquid crystal layer 30 having a refractive index close to that of the air layer. Further, the light travels straight in the region 48 that transmits light in the liquid crystal layer 30 and is scattered in the region 50 that scatters light. Even in this state, approximately 50% of the light emitted from the light source 20 illuminates the sub liquid crystal panel 36 and functions as backlight light.
What is important here is that most of the light is scattered in the region 50 where light is scattered to become backlight light. Therefore, for example, if the area of the light scattering region 50 is ½ of the entire liquid crystal region of the light guide member 56, the backlight light of the sub liquid crystal panel 36 in FIG. The amount of light per unit area of the backlight light of the main liquid crystal panel 34 in 3 (a) is approximately doubled. Conversely, when the main liquid crystal panel 34 and the sub liquid crystal panel 36 are illuminated with the same brightness, the power consumption of the light source 20 can be reduced when the sub liquid crystal panel 36 is illuminated as compared with the case where the main liquid crystal panel 34 is illuminated.
This point is greatly different from the conventional example shown in FIG. 10. With this effect, the liquid crystal device using the light scattering type liquid crystal panel as the light guide member can increase the illumination efficiency.
In FIG. 3, the liquid crystal panels 34 and 36 are drawn so that the backlight is incident obliquely. However, in the actual light guide member, the prism sheets 22 and 28 are used as shown in FIG. The backlight light enters the liquid crystal panels 34 and 36 at an angle closer to a right angle.

FIG. 4 shows an example in which the liquid crystal device of the present invention is used in a mobile phone. A keyboard 64 is provided on the main body 62 of the mobile phone 58, and the main liquid crystal panel 34, the sub liquid crystal panel 36, and the light source 20 are provided on the lid 60. The liquid crystal device of the present invention comprising the light guide member 56 is provided. In FIG. 4, the light source is not shown.
When the lid 60 is closed, the main liquid crystal panel 34 is turned off and the sub liquid crystal panel 36 is turned on, and the light guide member illuminates the sub liquid crystal panel 36 in the state shown in FIG.
When the cover 60 is open, the sub liquid crystal panel 36 is turned off and the main liquid crystal panel 34 is turned on, and the light guide member moves the main liquid crystal panel 34 in the state shown in FIGS. Illuminate.

FIG. 1 is a cross-sectional view of a first embodiment of a liquid crystal device according to the present invention.
In FIG. 1, 24 is an upper transparent substrate of a light scattering type liquid crystal panel constituting the light guide member 56, 10 is a lower transparent substrate, and 32 is a transparent electrode shown in FIG. 2 and 14 are provided on the lower transparent substrate 10, respectively. The lower transparent electrode having the shape shown in FIG. 2A and 26 is the upper transparent substrate 24. A polymer dispersed liquid crystal material, which is a light scattering type liquid crystal, is sandwiched in a region 30 surrounded by the transparent substrates 24 and 10 at the seal portion to which the lower transparent substrate 10 is bonded. Reference numeral 22 denotes an upper prism sheet and a 28 lower prism sheet, which function to condense light emitted from the light guide member in a desired direction. Reference numeral 20 denotes a light source that is provided on the side of the light guide member 56 and that makes light incident on the light guide member 56. The light source 20 includes an LED, and 18 denotes a reflector. A main liquid crystal panel 34 is provided above the light guide member 56, and a sub liquid crystal panel 36 is provided below the light guide member 56. A light-shielding reflecting plate 38 shown in FIG. 3B is provided below the lower transparent electrode 12 on the lower transparent substrate 10.

As is clear from the description of FIGS. 2 to 4, the light guide member 56 has an upper first surface and a lower second surface facing each other, and each surface serves as a light emitting surface. The light emitting area can be controlled by electrical means, the light emitting area of the first surface facing the c is shown in the figure, the light emitting area of the second surface is shown in the figure d, etc. The light emission areas are different from each other. Further, the light emission area of the first surface of the light guide member 56 is substantially equal to the size of the display area 34 of the main liquid crystal panel disposed to face the first surface, and the second area of the light guide member 56. The light emitting area d of the surface is set to be approximately equal to the size of the display area of the sub liquid crystal panel 36 disposed to face the second surface.

  With such a configuration, particularly when the sub liquid crystal panel 36 is illuminated, it is not necessary to illuminate unnecessary portions, so that power consumption can be reduced and high illumination efficiency can be achieved.

FIG. 5 is a sectional view of a second embodiment of the liquid crystal device according to the present invention.
5A and 5B are configured by adding a main liquid crystal panel 34 and a sub liquid crystal panel 36 as shown in the cross-sectional view of the light guide member 56 shown in FIGS. 2C and 2D. Has been.
In FIG. 5, the display liquid crystal panels 34 and 36 each have a display ON state with diagonal lines similar to those in FIG. 3, and the display OFF state is black with a white cross pattern (the OFF state is darker than the ON state) ).

  5 (a) and 5 (b), the light guide member 56 has first and second surfaces facing each other, that is, both the upper and lower sides of the drawing as light emitting surfaces, and the upper transparent electrode 32 and the lower transparent member. The light scattering region of the light scattering liquid crystal is electrically controlled by turning on and off the voltage applied between the electrodes 12 and 14. Further, a main liquid crystal panel 34 having a relatively large display area is disposed facing the upper surface of the light guide member 56, and a sub liquid crystal panel having a relatively small display area facing the lower surface of the light guide member 56. 36 is arranged.

FIG. 5A shows a state in which the main liquid crystal panel 34 is driven and display is ON, and the sub liquid crystal panel 36 is in display OFF. In this state, in order to illuminate the main liquid crystal panel 34, no voltage is applied between the upper transparent electrode 32 and the lower transparent electrodes 12 and 14, and the entire surface of the liquid crystal layer 30 is used as a light scattering region. Control is performed so that the size and the size of the light scattering region are substantially equal.
FIG. 5B shows a state in which the sub liquid crystal panel 36 is driven and display is ON, and the main liquid crystal panel 34 is in display OFF. In this state, in order to illuminate the sub liquid crystal panel 36, no voltage is applied between the upper transparent electrode 32 and the lower transparent electrode 14, and a voltage is applied between the upper transparent electrode 32 and the lower transparent electrode 12. 30, the entire surface of only the lower transparent electrode 14 is set as a light scattering region, and the size of the display region of the sub liquid crystal panel 36 and the size of the light scattering region are controlled to be approximately equal.
With this configuration, particularly when the sub liquid crystal panel 36 is illuminated, light is emitted only from the light scattering area having the same size as the display area of the sub liquid crystal panel 36, and unnecessary portions are illuminated. I don't need to. Therefore, power consumption can be reduced, and high lighting efficiency can be achieved.

FIG. 6 is a cross-sectional view of a third embodiment of the liquid crystal device according to the present invention.
The liquid crystal device of FIG. 6 has a configuration in which a transflective layer or a transflective plate 70 is added between the light guide member 56 and the sub liquid crystal panel 36 in the second embodiment of FIG.
With the configuration as shown in FIG. 6, a part of the light emitted to the sub liquid crystal panel 36 side is reflected to the main liquid crystal panel 34 side according to the reflectance of the transflective plate 70, and is used for illumination of the main liquid crystal panel 34. Contribute. On the other hand, the light emitted to the sub liquid crystal panel 36 is transmitted through the semi-transmissive reflector 70 according to the transmittance of the semi-transmissive reflector 70 to illuminate the sub liquid crystal panel 36.

As described with reference to FIG. 3A, even when the main liquid crystal panel 34 is illuminated, 50% of the light emitted from the light guide member 56 is emitted to the lower sub liquid crystal panel 36 side. Since the transflective plate 70 functions to return the light emitted downward to the main liquid crystal panel 34 side, the main liquid crystal panel 34 can be illuminated more brightly and with high efficiency.
As described with reference to FIG. 3C, when the same amount of light is emitted from the light source 20, the sub liquid crystal panel 36 is illuminated with a larger amount of light than the main liquid crystal panel 34 by an amount smaller than the area of the display area. Therefore, for example, when it is desired to change the light quantity of the light source 20 between when the main liquid crystal panel 34 is illuminated but cannot be changed when the sub liquid crystal panel 36 is illuminated, both the liquid crystal panels are displayed by the transflective plate 70 of FIG. The brightness of 34 and 36 can be adjusted, which is particularly effective.

A configuration in which the transflective plate 70 is provided between the light guide member 56 and the main liquid crystal panel 34 is also conceivable. Since the liquid crystal panel on the opposite side provided with the transflective plate 70 is displayed brighter, the selection of where to provide the transflective plate 70 and illuminate which liquid crystal panel is brighter should be appropriately determined. .
Further, the semi-transmissive reflection plate 70 can be provided between the prism sheet and the liquid crystal panel, or can be provided between the transparent substrate and the prism sheet.
That is, as shown in the figure, the prism sheet 22 provided between the prism sheet 28 and the sub-liquid crystal 36, provided between the prism sheet 22 and the main liquid crystal 34, and provided between the prism sheet 28 and the lower transparent substrate 10. There are four options of providing between the upper transparent substrate 24 and the upper transparent substrate 24.

FIG. 7 is a sectional view of a fourth embodiment of the liquid crystal device according to the present invention.
The liquid crystal device of FIG. 7 is different from the second embodiment of FIG. 5 in that polarization separation sheets 74 and 76, which are polarization separation layers, are added between the light guide member 56, the main liquid crystal panel 34, and the sub liquid crystal panel 36, respectively. It has a configuration. For the sake of explanation, a lower linear polarizing plate 72 in the main liquid crystal panel 34 and an upper linear polarizing plate 78 in the sub liquid crystal panel 36 are shown.

Here, the polarization separation sheet will be described.
The polarization separation sheet is a sheet having a separation function of transmitting light in one polarization state of two polarization states and reflecting light in the other polarization state, and has a transmission axis and a reflection axis. A reflective polarizing plate, which is a so-called reflective polarizing layer, is included in the concept of this deflection separation sheet. In the embodiment, an example in which a linear deflection separation sheet that separates two kinds of linearly polarized light that is orthogonal is shown, but a circular deflection separation sheet that separates two kinds of circularly polarized light having different rotation directions is used. If a 1 / 4λ plate which is a / 4λ layer is provided, the same effect as that obtained when a linearly polarized light separating sheet for separating linearly polarized light is used is produced.

FIG. 7A is a diagram showing a cross-sectional configuration of the fourth embodiment, and FIG. 7B is a diagram showing the behavior of light in the liquid crystal device having the same configuration as FIG.
In FIG. 7A, the transmission axis of the upper polarization separation sheet 74 and the transmission axis of the linear polarization plate 72 which is the linear polarization layer of the main liquid crystal panel 34 are matched, and the transmission axis of the lower polarization separation sheet 76 and the sub liquid crystal are aligned. The transmission axes of the linear polarizing plates 78 of the panel 34 are made coincident with each other, and the transmission axis of the upper polarization separation sheet 74 and the transmission axis of the lower polarization separation sheet 76 are orthogonal to each other.

In FIG. 7B, the light 77 shown by a solid line is totally reflected by the upper transparent substrate 24 and then scattered in the light scattering liquid crystal layer 30 and travels upward and downward. The light component of the upward light that coincides with the transmission axis of the upper polarization separation sheet 74 passes through the upper polarization separation sheet 74 and reaches the linearly polarizing plate 72, but the transmission axis of the upper polarization separation sheet 74 and the main liquid crystal panel 34. Since the transmission axes of the linear polarizers 72 coincide with each other, they pass through the linear polarizer 72 and become illumination light of the main liquid crystal panel 34. The light component perpendicular to the transmission axis of the inner and lower polarization separation sheets 76 of the light directed downward is reflected by the lower polarization separation sheet 76 and travels upward. In the meantime, it is scattered again in the light scattering liquid crystal layer 30, but finally reaches the upper polarization separation sheet 74. Since this light is light of a polarization component orthogonal to the transmission axis of the lower polarization separation sheet 76, it passes through the upper polarization separation sheet 74 and the linear polarization plate 72 and becomes illumination light for the main liquid crystal panel 34.
The light 79 indicated by the broken line is totally reflected by the lower transparent substrate 10 and then scattered in the light scattering liquid crystal layer 30 and travels upward and downward. The light component of the light directed downward that coincides with the transmission axis of the inner lower polarization separation sheet 76 is transmitted through the lower polarization separation sheet 76 and reaches the linear polarizing plate 78. Since the transmission axes of the linear polarizing plates 78 of the liquid crystal panel 36 coincide with each other, they pass through the linear polarizing plate 78 and become illumination light of the sub liquid crystal panel 36. The light component perpendicular to the transmission axis of the inner upper polarization separation sheet 74 is reflected by the upper polarization separation sheet 74 and travels downward. In the meantime, the light is scattered again in the light scattering liquid crystal layer 30, but finally reaches the lower polarization separation sheet 76. Since this light is light of a polarization component orthogonal to the transmission axis of the upper polarization separation sheet 74, it passes through the lower polarization separation sheet 76 and the linear polarizing plate 78 and becomes illumination light for the sub liquid crystal panel 36.

  As described above, according to the fourth embodiment shown in FIG. 7, almost 100% of the light traveling in the opposite direction to the liquid crystal panel to be illuminated can be used. This light efficiency is almost the same as that of a conventional backlight that emits light only to one side, but high illumination efficiency can be realized while illuminating two liquid crystal panels provided on both sides with one light source and a light guide member. The remarkable effect is produced.

8A and 8B show a fifth embodiment of the liquid crystal device according to the present invention. FIG. 8A is a sectional view, and FIG. 8B is a plan view showing the positional relationship between the sub liquid crystal panel 36 and the reflecting plate 80. .
The liquid crystal device of FIG. 8 has a configuration in which a reflecting plate 80 is added to a portion other than the display area of the sub liquid crystal panel 36 as shown in the figure in the second embodiment of FIG.
The reflectance of the reflecting plate 80 which is a reflecting layer is matched to the reflectance of the surface of the sub liquid crystal panel 36 on the light guide member 56 side.
With this configuration, when the main liquid crystal panel 34 is illuminated, it is possible to prevent unevenness in the brightness of the main liquid crystal panel 34 due to light reflection of the sub liquid crystal panel 36.

FIG. 9A is a sectional view of a sixth embodiment of the liquid crystal device according to the present invention, and FIG. 9B is a sectional view of a modified example of FIG.
FIG. 9A is different from the second embodiment of FIG. 5 in that the lower transparent substrate 10 of the light guide member 56 is extended to one side and the light of the light source 20 is incident thereon. It is. Further, a polarization separation sheet 74 is provided between the light guide member 56 and the main liquid crystal panel 34.
Further, the transmission axes of the polarization separation sheet 74 and the linear polarization plates 72 and 78 are set so that the transmission axes of the polarization separation sheet 74 and the linear polarization plate 72 are parallel and the transmission axes of the polarization separation sheet 74 and the linear polarization plate 78 are orthogonal to each other. Has been.

In the sixth embodiment of FIG. 9, the light passing through the layer to which no voltage is applied is applied to the polymer dispersed liquid crystal, which is a light scattering type liquid crystal, but scattered backward with respect to the traveling direction of the light. It was conceived from the fact that light was found to be scarce.
In FIG. 9A, the light emitted from the light source 20 is totally reflected by the lower transparent substrate 10 and then scattered in the light scattering liquid crystal layer 30 and mainly travels upward. The light component of the upward light that coincides with the transmission axis of the upper polarization separation sheet 74 passes through the upper polarization separation sheet 74 and reaches the linearly polarizing plate 72, but the transmission axis of the upper polarization separation sheet 74 and the main liquid crystal panel 34. Since the transmission axes of the linear polarizing plates 72 coincide with each other, they pass through the linear polarizing plate 72 and become illumination light of the main liquid crystal panel 34. Since the light directed downward is light having a polarization component parallel to the transmission axis of the linear polarizing plate 78 of the sub liquid crystal panel 36, it passes through the linear polarizing plate 78 and becomes illumination light for the sub liquid crystal panel 36. Therefore, in this configuration, the light that illuminates the sub liquid crystal panel 36 is mainly reflected light from the polarization separation sheet 74.
In this configuration, light that contributes to illumination of the main liquid crystal panel 34 is less likely to be lost due to repeated reflection, so that a larger amount of light can be given to the main liquid crystal panel 34.
Further, as described above, the sub liquid crystal panel 36 is given a large amount of light by narrowing the light scattering region of the liquid crystal layer 56, so that the illumination light may be mainly reflected light from the polarization separation sheet 74. .

With such a configuration, an effect equivalent to or greater than that of the fourth embodiment of FIG. 7 using only two polarization separation sheets can be produced. Therefore, in addition to the high efficiency of illumination, there is an effect of reducing the cost of the liquid crystal device.
Note that the polarization separation sheet 74 may be approximately the same size as the display area of the sub liquid crystal panel 36, as shown in FIG. 9B.
When the illumination of the sub liquid crystal panel 36 is mainly considered, the positional relationship between the main liquid crystal panel 34 and the sub liquid crystal panel may be reversed. It is better to determine which lighting is set brighter as appropriate.

FIG. 9B is a modification in which the technique of the fifth embodiment shown in FIG. 8 is applied to the technique of the sixth embodiment of FIG.
FIG. 9B is different from FIG. 9A in that a reflecting plate 80 is added to a portion other than the display area of the sub liquid crystal panel 36.
With this configuration, as in the case of FIG. 8, when the main liquid crystal panel 34 is illuminated, it is possible to prevent the brightness of the main liquid crystal panel 34 from becoming uneven due to the light reflection of the sub liquid crystal panel 36. I can do it.
Note that the reflection plate 80 as the reflection layer may be provided between the lower transparent substrate 10 and the prism sheet 28.

As described above, according to the present invention, two back-to-back liquid crystal panels can be illuminated with high efficiency by one light source and a light guide member, which has a great effect on reduction in thickness and power consumption.
Of course, the same effect can be expected if the technique of the present invention is applied not only to a liquid crystal panel but also to a light receiving display panel.

It is sectional drawing of the 1st Example of the liquid crystal device by this invention. It is a figure explaining the light guide member used with the liquid crystal device by this invention. It is a figure explaining the behavior of the light in the light guide member used with the liquid crystal device by this invention. This is an example in which the liquid crystal device of the present invention is used in a mobile phone. It is sectional drawing of the 2nd Example of the liquid crystal device by this invention. It is sectional drawing of the 3rd Example of the liquid crystal device by this invention. It is sectional drawing of the 4th Example of the liquid crystal device by this invention. It is a 5th Example of the liquid crystal device by this invention. It is sectional drawing of the 6th Example of the liquid crystal device by this invention. It is a figure which shows the conventional liquid crystal device.

Explanation of symbols

34 Main liquid crystal panel 36 Sub liquid crystal panel 56 Light guide member 20 Light source 56 Light scattering type liquid crystal panel 70 Transflective reflection plates 74 and 76 Polarization separation sheet 38 Light blocking reflection plate 80 Reflection plates 10 and 24 Transparent substrate 30 Light scattering type liquid crystal layer 22, 28 Prism sheet 12, 14, 32 Transparent electrode 18 Reflector 26 Seal 72, 78 Linearly polarizing plate

Claims (12)

And two liquid crystal panels to be laminated, is arranged between the two liquid crystal panels, and the light guide member for illuminating these liquid crystal panels, the liquid crystal device having a light source disposed on the side of the light guide member,
The light guide member includes a feature that has become a first surface and a second surface, respectively and the light emitting surface, the size can be controlled by electrical means the light scattering type liquid crystal panel of the scattering region facing Liquid crystal device.   2. The liquid crystal device according to claim 1, wherein the light scattering liquid crystal panel is a polymer dispersion type liquid crystal panel. The light guide member is a liquid crystal device according to claim 1 or 2 size of a light emitting region of the first face and the second opposing surfaces are different from each other. Wherein said liquid crystal panel so as to face the first surface and the second surface of the light guide member are disposed respectively, the liquid crystal panel, which is a liquid crystal panel having a different display area Item 4. The liquid crystal device according to any one of Items 1 to 3 . The liquid crystal panels respectively disposed facing the first surface and the second surface of the light guide member have display areas of different sizes,
The light emitting area of the first surface of the light guide member is approximately equal to the size of the display area of the liquid crystal panel disposed to face the first surface,
2. The light emitting area on the second surface of the light guide member is set to be approximately equal to the size of the display area of the liquid crystal panel disposed to face the second surface. 5. The liquid crystal device according to any one of 4 . In a liquid crystal device having a liquid crystal panel, a light guide member that illuminates the liquid crystal panel, and a light source disposed on a side of the light guide member,
The light guide member includes a light scattering type liquid crystal panel in which the first surface and the second surface facing each other are light emission surfaces, and the light scattering region can be controlled by electric means,
A liquid crystal panel is disposed opposite to the first surface and the second surface of the light guide member,
Each of the liquid crystal panels is composed of a main liquid crystal panel having a relatively large display area and a sub liquid crystal panel having a relatively small display area.
When the main liquid crystal panel is driven, the light scattering area of the light guide member is controlled to be approximately equal to the size of the display area of the main liquid crystal panel, and when the sub liquid crystal panel is driven A liquid crystal device controlled to be approximately equal to the size of the display area of the sub liquid crystal panel. The liquid crystal device according to claim 6, wherein the light scattering liquid crystal panel is a polymer dispersion type liquid crystal panel. The liquid crystal device according to any one of claims 1 to 7, characterized in that a semi-transmissive reflective plate between one and the guiding member of the liquid crystal panel. The liquid crystal device according to any one of claims 1, characterized in that a polarization separation sheet 7 between the guide member and the liquid crystal panel. 8. The liquid crystal device according to claim 6 , wherein a reflection plate is provided in a portion other than the display area of the sub liquid crystal panel on the surface of the light guide member on the sub liquid crystal panel side. The light guide member is to hold the light-scattering-type liquid crystal material with a transparent substrate of the two opposing,
The light from the light source is incident on one of the opposing transparent substrates of the light guide member,
The liquid crystal according to claim 1, wherein a polarization separation sheet is provided between the other transparent substrate of the transparent substrates facing the light guide member and one of the liquid crystal panels. apparatus. The light guide member is to hold the light-scattering-type liquid crystal material with a transparent substrate of the two opposing,
The light from the light source is incident on one of the opposing transparent substrates of the light guide member,
A polarizing separation sheet is provided between the other transparent substrate of the transparent substrates facing the light guide member and one of the liquid crystal panels,
Place the sub liquid crystal panel on the transparent substrate side of the light guide member into which the light of the light source is incident,
8. The liquid crystal device according to claim 6, wherein a reflection plate is provided in a portion other than the display area of the sub liquid crystal panel on the surface of the light guide member on the sub liquid crystal panel side.

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