JPH0973083A - Illuminator and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illuminator for which a light source is efficiently made use of, generating a compact linearly polarized light and to provide a liquid crystal display device with a high luminosity, a less power consumption, and a high utilization factor of light. SOLUTION: This device is provided with a light source 501, a polarized light separation means 503 by helical structure molecule which separates the light from the light source 501 into a first circularly polarized light and a second circularly polarized light of which the rotation direction of the vibration planes are in the reverse direction to each other, namely, the first circularly polarized light is separated by transmission, the second circularly polarized light by reflection, a circularly polarized light conversion means to convert the second circularly polarized light into the first circularly polarized light and a polarized light conversion means 504 to convert the first circularly polarized light having passed through the polarized light separation means into linearly polarized light, and an light guide means to make the light from the light source or the first circularly polarized light incident to the polarized light separation means with a prescribed incident angle. The device is also provided with a vibration plane conversion means to convert the vibration plane of the linearly polarized light so that it passes through the polarization plate on the side of the liquid crystal panel side and a second light guide means to guide the linearly polarized light to the liquid crystal panel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device that produces polarized light and a display device using the same, and more particularly to a liquid crystal display device.

[0002]

2. Description of the Related Art Illumination devices that generate polarized light are widely used in optical systems that use polarized light, including the light source of a polarization microscope. As an optical system using such polarized light, for example, a liquid crystal display device or a projection type display device has been attracting attention in recent years.

Liquid crystal display devices are widely used because they are thin, lightweight, and have low power consumption. The most commonly used display method of liquid crystal display devices is to provide polarizing plates on both sides of a glass substrate holding a liquid crystal and electromagnetically control the alignment state of the liquid crystal to change the polarization state of incident light. It is a thing. That is, this is a method of performing bright / dark display by transmitting or not transmitting light to the liquid crystal panel, and the liquid crystal itself is passive display that does not emit light. Therefore,
In order to secure screen brightness and obtain good image quality, it is necessary to provide an illuminating device and illuminate from the back of the liquid crystal panel.

In the conventional illuminating device of the display device, the one using a fluorescent tube luminous body such as a cold cathode tube as a light source is the mainstream. As the structure, as shown in FIG. 26, a light guide plate 2602 and a light source 2603 are arranged below the liquid crystal panel 2601, and an edge light system in which the light source light is incident from the end face of the light guide plate 2602 to illuminate the light is also used. As shown in FIG. 27, there is known a direct system in which a light source 2702 is arranged below the liquid crystal panel 2701 and the light is illuminated from directly under the liquid crystal panel. Lighting by edge light method can make the device thin,
Further, it has a characteristic that the brightness is highly balanced, but there is a problem that the utilization rate of light is low and the brightness is high, and at the same time, the power consumption is also a problem.

The light guide plate is for taking out the light source light over the entire liquid crystal panel, and allows the light source light to enter from the end surface of the light guide plate directly or after being reflected by the reflector. The light that has entered the light guide plate undergoes total reflection and is repeatedly reflected with almost no attenuation. The upper or lower surface of the light guide plate is treated with white printing, aluminum vapor deposition, Fresnel mirror, etc. to cause reflection or scattering.When light is incident on the treated surface, the reflection direction changes due to the diffuse reflection effect. Then, the light is emitted from the light guide plate in the illumination direction. The light guide plate is equipped with a diffuser plate for equalizing the distribution of illumination light to the liquid crystal panel, a prism sheet for controlling the emission direction to an appropriate angle, and a white reflector plate under the light guide plate. Many devices are equipped with. By providing such an illuminating device below the liquid crystal panel, a bright and high-contrast liquid crystal display device is realized.

However, since the light from the light emitting body which is the light source is generally non-polarized light, when the light emitted from the conventional lighting device passes through the polarizing plate provided on the light incident side of the liquid crystal panel, About half of the light that does not coincide with the transmission axis is absorbed, and the illumination light that is effectively used becomes half or less of the light emitted from the light source of the illumination device, resulting in a low light utilization efficiency. Therefore, in order to realize a liquid crystal display device with sufficiently high brightness, it is necessary to increase the amount of light emitted from the light source of the lighting device, resulting in an increase in power consumption.

As one of means for solving this problem, in a lighting device applied to a projection type liquid crystal display device instead of a direct view type, the light source light is divided into two orthogonal linearly polarized lights, and one of the polarized lights is polarized. A method has been proposed in which a component is converted into the other polarized component and then incident on a polarizing plate. But,
In order to perform polarization conversion by such a method, in principle
A large dimensional space is newly required and the device becomes large. Such an illuminating device can be applied to a liquid crystal display device such as a projection type liquid crystal display device which does not require much flatness, but when applied to a direct view type liquid crystal display device,
There is a problem that major characteristics of the liquid crystal display device such as thinness and lightness are lost.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. That is, an object of the present invention is to provide a lighting device that can effectively use the light from the light source and that produces polarized light of the same polarity.

An object of the present invention is to provide a liquid crystal display device having high brightness and low power consumption and high utilization rate of light from a light source.

[0010]

An illuminating device of the present invention includes a light source, a first circularly polarized light and a second circularly polarized light whose light source light from the light source are opposite to each other in directions of rotation of oscillating planes. Polarization separation means by a helical structure molecule that separates by transmitting the first circularly polarized light and reflecting the second circularly polarized light; a circularly polarized light converting means that converts the second circularly polarized light into the first circularly polarized light; Alternatively, it is provided with a light guide means for making the first circularly polarized light incident on the polarized light separating means at a predetermined incident angle, and a phase converting means for converting the first circularly polarized light transmitted through the polarized light separating means into linearly polarized light. And

Further, the light source and the light source light from the light source are transmitted to the first circularly polarized light and the second circularly polarized light whose vibrating surfaces are opposite to each other in the rotation directions, and the first circularly polarized light is transmitted to the second circularly polarized light. The polarized light is separated by reflecting the polarized light, and the polarized light is separated by a spiral structure molecule. The circularly polarized light is converted into the first circularly polarized light. The source light or the first circularly polarized light is incident at a predetermined incident angle. First light guide means for making the light incident on the polarized light separating means, phase conversion means for converting the first circularly polarized light transmitted through the polarized light separating means into linearly polarized light, and guiding the light transmitted through the polarized light separating means in a predetermined direction. It is characterized by comprising a second light guide means.

The polarized light separating means is at least 420-
450nm, 520-570nm, 590-630nm
Is characterized by having an interference wavelength region of circularly polarized light selective reflection. Further, the main emission spectrum of the light source is included in the interference wavelength region of the polarization separation means. The main emission spectrum of the light source may be included between the center wavelength of the interference wavelength region of the polarization splitting means and the short wavelength side interference edge wavelength.

The liquid crystal display device of the present invention includes a liquid crystal panel having a liquid crystal layer and a polarizing plate, a light source, and a first circularly polarized light and a second circularly polarized light whose source vibrations are opposite to each other. A polarized light separating means using a helical structure molecule that separates the first circularly polarized light by transmitting it and the second circularly polarized light by reflecting it, and a circularly polarized light converting means that converts the second circularly polarized light into the first circularly polarized light. A first light guide means for making the light source light or the first circularly polarized light incident on the polarized light separating means at a predetermined incident angle; and a phase converting means for converting the first circularly polarized light transmitted through the polarized light separating means into linearly polarized light. And a second light guide means for guiding the light to the liquid crystal panel while maintaining the linearly polarized light.

Further, the liquid crystal display device of the present invention includes a liquid crystal panel having a liquid crystal layer and a polarizing plate, a light source, and first circularly polarized light whose vibrating planes have opposite rotation directions. Polarization separating means by a helical structure molecule that separates the second circularly polarized light by transmitting the first circularly polarized light and reflecting the second circularly polarized light, and a circle that converts the second circularly polarized light into the first circularly polarized light Polarization conversion means, first light guide means for making the source light or first circularly polarized light incident on the polarization separation means at a predetermined incident angle, and first circularly polarized light transmitted through the polarization separation means for conversion to linearly polarized light. It comprises a phase conversion means, a vibrating surface conversion means for converting a vibrating surface of linearly polarized light so as to pass through a light incident side polarizing plate of the liquid crystal panel, and a second light guide means for guiding the linearly polarized light to the liquid crystal panel. It is characterized by

The illuminating device of the present invention is capable of taking out substantially all of the light from the light source emitted from the light source as circularly polarized light or linearly polarized light having uniform polarity.

Here, the circularly polarized light includes circularly polarized light in which the vibrating planes of different polarities rotate in the clockwise direction and circularly polarized light in the counterclockwise direction. The first circularly polarized light is circularly polarized light in the clockwise direction. The second circularly polarized light may correspond to the counterclockwise circularly polarized light, or the first circularly polarized light may correspond to the counterclockwise circularly polarized light.
The second circularly polarized light may correspond to the clockwise circularly polarized light. The same applies to the case where no particular description is given below.

In the present invention, the light from the light source is separated into the first circularly polarized light and the second circularly polarized light whose properties are interchanged by reflection, the first circularly polarized light is transmitted, and the second circularly polarized light is A polarized light separating means using a helical structure molecule that reflects light is used. Such polarized light separating means using molecules having a helical structure may be a substance having a light-transmitting property having a microscopically helical structure that causes optical interference at a predetermined wavelength, and preferably the first It is preferable that only the circularly polarized light of (2) is selectively and completely transmitted, and the second circularly polarized light is not absorbed and is totally reflected. For example, cholesteric liquid crystal may be used.

When the cholesteric liquid crystal is used, it may be used by injecting it into the cell, or it may be polymerized with the UV curable resin or the thermosetting resin while maintaining the coherence. As a shape, a sheet-shaped cholesteric liquid crystal sheet having a thickness sufficient for optical interference may be prepared and used. Also, for example, when a plurality of cholesteric liquid crystal sheets are laminated and used, the circular polarization components having the same polarity may be transmitted or reflected in the interference wavelength range of each sheet.

The interference region of the circularly polarized light separating means needs to include the emission spectrum wavelength region of the light source light. When a fluorescent tube is used as a light source, for example, 420 to 450 nm and 520 to 570 n are included so as to include main emission spectrum peaks of each color of blue, green and red in the emission spectrum of the three-wavelength tube.
It is sufficient to use a polarized light separating means having an interference region in the wavelength region of m, 590 to 630 nm.

The interference wavelength range of these polarized light separating means is
When light is obliquely incident, the interference wavelength region shifts to the short wavelength side. Therefore, the interference wavelength region may be provided on the long wavelength side with respect to the peak of the emission spectrum within a range in which the emission spectrum of the light source is sufficiently included under the condition of vertical light incidence. When the incident angle of the light entering the polarization splitting means is controlled to be vertical, the center of the interference wavelength region may coincide with the center of the peak of the emission spectrum of the light source.

Further, in order to maintain sufficient circularly polarized light selectivity as the polarized light separating means, the light incident condition is ± 20 from vertical incidence.
The light may be condensed and incident at an angle of less than °.

A plurality of cholesteric liquid crystal layers each having an interference wavelength region for each wavelength region may be laminated and used.

Further, when a plurality of polarization separating means are laminated and used, the interference materials at the respective wavelengths have the same polarity so that circular polarization components having the same polarity are transmitted or reflected in the respective wavelength interference regions. It has an ability to interfere with polarized light. That is, in each polarization separation means, the c-axes of the spiral structure molecules are aligned parallel to the incident direction of light, and the spiral directions are aligned within each polarization separation means or between polarization separation means. To That is, when a sheet-shaped polarized light separating means is used, the c-axes of all helical molecules are oriented perpendicular to the sheet surface, and the helices are aligned so as to be right-handed or left-handed. When using a plurality of polarized light separating means, the directions of the spiral molecules are unified between the respective polarized light separating means, that is, right-handed or left-handed.

When the cholesteric liquid crystals are laminated and used, for example, a glass substrate or a plastic sheet substrate may be used between the respective cholesteric liquid crystal layers to form a sheet. Alternatively, the cholesteric liquid crystal may be directly applied onto the substrate by spin coating or a printing method, and may be prepared by repeating the step of curing. As the substrate material, those having high transparency and high refractive index and low birefringence and dispersibility are preferable. For example, glass or PM
MA, PC, CR-39, MS resin, AS resin, TPX
You may make it use resin such as.

When the present invention is applied to, for example, an edge-light type illumination device, the polarized light separating means may be arranged between the light source and the light guide plate, or on the light emitting side of the light guide plate. You may do it. When it is applied to a direct type illumination device, it may be arranged between the light source and the diffusion plate. In this way, where to arrange the polarized light separating means in the optical system of the illuminating device may be designed according to the application and need. Further, the illuminating device of the present invention comprises light guide means for guiding the light source light from the light source or the second circularly polarized light reflected by the polarization separating means to the polarization separating means,
A polarization conversion means for converting the second circularly polarized light and the first circularly polarized light is provided.

As the first and second light guide means, a reflecting mirror, a light guide plate, a prism, a waveguide such as an optical fiber, a holographic optical element (HOE), a diffusion plate, an AR coat, etc. may be used. . Also, a plurality of these light guide means may be combined and used. When the reflecting means such as a reflecting mirror or prism is used as the first light guide means, this light guide means also functions as the polarization conversion means. A mirror surface, a non-linear optical element, or the like may be used as the polarization conversion means. When a mirror surface is used as the polarization conversion means, for example, a reflector, a surface of a light source, a reflection surface such as a reflection plate of a light guide plate may be used. You may make it use combining these polarization conversion means in plurality. It may also serve as a reflector that reflects the light from the light source.

When the second circularly polarized light is reflected by the mirror surface to be converted into the first polarized light, this polarization conversion means also functions as a light guide means. The second circularly polarized light which cannot be transmitted through the polarized light separating means and is reflected is converted into the first polarized light by the polarization converting means, and the first polarized light is transmitted through the polarized light separating means.

Further, if an auxiliary light guide plate as shown in FIGS. 8, 9, 10 and 11 is used as the polarization converting means and the light guiding means, the polarization separation ability is improved.

The arrangement of these light guide means and polarization conversion means may be designed as necessary. For example,
A light guide unit and a polarization conversion unit may be arranged between the light source and the polarization separation unit so that the polarized light is incident on the light guide plate. Further, for example, a light guide plate may be used as a light guide unit and a polarization conversion unit arranged between the light source and the polarization separation unit, and the polarization separation unit may be arranged on the light emission side of the light guide plate. The light guide plate may be provided with a reflection means.

By these polarized light separating means, light guide means and polarized light converting means, substantially all the light source light is emitted from the polarized light separating means as the first circularly polarized light.

If this illuminating device is provided with a phase converting means such as a quarter-wave plate, linearly polarized light can be immediately extracted.

As a phase conversion means for converting circularly polarized light into linearly polarized light, for example, a retardation film made of PVA or the like may be used as a quarter wavelength plate. 1
The direction in which the / 4 wavelength plate is arranged is such that the polarization state is preserved even if reflection is repeated between the upper and lower reflection surfaces of the light guide plate when the polarization separation means is provided between the light source and the light guide plate. , The fast axis is 4 with respect to the side direction of the light guide plate so as to be converted into linearly polarized light which is horizontal or vertical to the reflection surface of the light guide plate.
Set to 5 °.

Further, for example, when the polarization separating means is provided on the upper surface of the light guide body, that is, between the light guide plate and the display screen, the direction of the fast axis is set so that the converted linearly polarized light has a desired direction. Good.

Considering a direct-viewing type liquid crystal display device, the polarizing plate transmission axis direction is usually 45 ° with respect to the display screen side direction due to the problem of viewing angle. Therefore, in order for the linearly polarized light emitted as illumination light from the light guide plate side to be parallel to the transmission axis direction of the polarizing plate, when the polarizing molecular element is between the light source and the light guide plate, the polarized light emitted from the light guide plate is the screen side direction. On the other hand, since it is in the horizontal or vertical direction, a ½ wavelength film may be newly added between the light guide plate and the liquid crystal panel as a vibration plane conversion means. At that time, if the fast axis of the ½ wavelength film is arranged at a position that bisects an angle that makes an acute angle between the polarization direction and the transmission axis of the polarizing plate, the azimuths of the linearly polarized light and the transmission axis of the polarizing plate are matched by polarization rotation. Can be made.

When the polarized light separating means is between the light guide plate and the liquid crystal panel, it is only necessary to match the directions when converting the circularly polarized light into the linearly polarized light. According to the relationship between the rotation direction and the polarizing plate transmission axis, they may be arranged so as to be parallel to the upper and lower sides of the screen or the left and right sides of the screen.

The material required for the light guide plate is the same as the above-mentioned substrate material, and glass, PMMA, PC or the like may be used. In addition, the depolarization property is required to be as small as possible in order to maintain the polarization degree of light. Therefore, the light guide plate is required to have a small birefringence Δn, and the preferable birefringence is Δn <10 −5, more preferably Δn <
10-7 is good. For that purpose, the light guide plate may be manufactured by injection molding, or sufficient annealing may be performed after thermoplastic molding to remove the internal stress.

Further, it is necessary to provide a surface which causes specular reflection instead of diffuse reflection as a reflection surface for eliminating total reflection of the light guide plate and for emitting light to the upper surface of the light guide plate.
Therefore, for example, wedge-shaped concavities and convexities may be provided as the reflection surface of the light guide plate to change the reflection angle so that the light is emitted outside the light guide plate. Further, a reflection means such as a reflection sheet may be provided below the light guide. The reflecting sheet may be a mirror surface of a metal having a high reflectance such as aluminum.

In the illuminating device of the present invention, as a part of the light guide means, more appropriate and efficient light from the light source such as means for uniformizing the emitting direction of the illuminating light, condensing the light, or adjusting the refractive index. You may make it provide the means for leading to the display screen.

As a means for making the emitted light uniform, for example, a diffusion plate may be used. A frosted glass or a holographic optical element having a low depolarizing property may be used for the diffusion plate.

As the means for collecting the emitted light, for example, a prism sheet, an auxiliary light guide plate, a microlens, a holographic lens array or the like may be used. As a means for adjusting the refractive index, for example, an AR coat may be applied so as to reduce an interface reflection component of an optical system such as a light guide plate into which light enters from an air layer. Alternatively, for example, an AR coat film may be attached.

In the illumination device of the present invention, the light source light emitted from the light source is incident on the polarization splitting means by the first light guide means. The light from the light source incident on the polarized light separating means is
Of the first circularly polarized light and the second circularly polarized light of which the first circularly polarized light is transmitted through the polarized light separating means and is emitted to the side opposite to the light source. The second circularly polarized light is reflected to the light source side. The second circularly polarized light is converted into the first circularly polarized light by the polarization conversion means, and is guided to the polarization separation means again by the first light guide means.

According to the illumination device of the present invention, the light emitted from the light source is emitted as the first circularly polarized light with almost no loss.

If the phase conversion means is provided, the light emitted from the light source is emitted as linearly polarized light with almost no loss.

Further, when the auxiliary light guide plate is used as the first polarization conversion means and the light guide means, the polarization separation ability is improved.

In the liquid crystal display device of the present invention, the unpolarized light source light emitted from the light source is incident on the polarization splitting means and split into the first circularly polarized light and the second circularly polarized light. The polarity of the circularly polarized light of the second circularly polarized light reflected on the light source side is inverted by the polarization conversion means and becomes the transmitted light of the polarized light separation means.

Circularly polarized light of uniform polarity is converted into linearly polarized light when passing through the phase conversion means. For the linearly polarized light, the emission direction is changed while maintaining the polarization state by the second light guide means,
The light enters the vibrating surface conversion means, is converted into a vibrating surface that passes through the incident side polarization plate of the liquid crystal panel, and enters the liquid crystal panel.

[0047]

1 is a perspective view schematically showing an example of a lighting device of the present invention.

This illuminating device uses a cold cathode fluorescent tube 101 as a light source. The cold-cathode fluorescent tube 101 corresponds to each of blue, green, and red, and has a wavelength of 420 to 450 nm and 520
It is a three-wavelength tube having a main emission spectrum at 570 nm and 590 to 630 nm. A reflector 102 having a U-shaped cross section is provided so as to surround the cold cathode fluorescent tube 101 and reflects light in a predetermined direction.

A polarized light separating means for transmitting the first polarized light and reflecting the second polarized light is disposed on the opening side of the reflector 102. As the polarized light separating means, three layers of cholesteric liquid crystal sheets 103, 104 and 105 having an interference wavelength region corresponding to the wavelength region of the main light emission spectrum of the light source are laminated and sandwiched between glass substrates 106 and 107.

A glass layer may be provided between the respective cholesteric liquid crystal layers as the polarized light separating means. Further, these cholesteric liquid crystal layers may be sandwiched between the glasses to be separately manufactured and bonded to each other. In this case, the refractive index matching between the glasses may be performed. At least 1 of these glass layers
mm or less.

These cholesteric liquid crystal sheets 103,
104 and 105 are arranged so that circularly polarized light having the same polarity is transmitted or reflected. Further, the number of cholesteric liquid crystal sheets may be used according to the number of main emission spectra of the light source, the wavelength region, and the like.

These cholesteric liquid crystal sheets produce 50% transmission (first circularly polarized light component) and 50% reflection (second circularly polarized light component) in each interference wavelength region for non-polarized light incident, Virtually no light loss. In addition, the light is 100% transmitted outside the interference wavelength region. Therefore, when non-polarized white light is incident on the polarized light separating means composed of the cholesteric liquid crystal sheet having such characteristics, it can be separated into two circularly polarized lights very efficiently.

In the illumination device shown in FIG. 1, the surface of the cold cathode fluorescent tube 101, the reflector 102, and the glass substrate 10 are provided.
6 functions as a light guide unit or a polarization conversion unit.

The light emitted from the cold cathode fluorescent tube 101 is
Cholesteric liquid crystal sheets 103, 104, which are polarization separating means directly or reflected by the reflector 102,
It enters 105. The light source light that has entered the polarization separation means is separated into first circularly polarized light and second circularly polarized light, and the first circularly polarized light passes through the polarization separation means and is emitted to the side opposite to the light source. Second
The circularly polarized light of is reflected to the light source side. This second circularly polarized light is
The light is reflected by the surface of the cold-cathode fluorescent tube 101, the reflector 102, and the glass substrate 106 and is guided again to the polarized light separating means. Since the polarity of the circularly polarized light is converted upon reflection, the second circularly polarized light is converted into the first circularly polarized light. The first circularly polarized light may be converted into the second circularly polarized light, but the second circularly polarized light cannot be transmitted through the polarization separating means and is reflected. Therefore,
According to the illumination device of the present embodiment, the light emitted from the cold cathode fluorescent tube 101, which is the light source, can be emitted to the glass substrate 107 side as the first circularly polarized light with almost no loss.

FIG. 2 shows the relationship between the light source and the optical characteristics of the cholesteric liquid crystal sheet when the cholesteric liquid crystal sheet is used as the polarized light separating means.

The light source uses a three-wavelength fluorescent tube having three main emission spectra. Each emission spectrum is 4
40 nm blue (B) emission spectrum 201, 550n
m is a green (G) color emission spectrum 202 and 610 nm is a red (R) color emission spectrum 203, and the half width of each spectrum is about 10 nm.

On the other hand, the transmittance characteristic of the cholesteric liquid crystal sheet corresponding to each emission spectrum of BGR under the condition of non-polarized incidence is 204, which has an interference wavelength region in blue,
205 has an interference wavelength region in green and 206 has an interference wavelength region in red. These interference wavelength regions should sufficiently include the peak of the main emission spectrum of the light source described above. Further, as will be described later, the relative relationship between the interference wavelength region and the main emission spectrum may be determined so that the peak of the main emission spectrum is on the shorter wavelength side than the center of the interference wavelength region.

FIG. 3 is a diagram showing the relationship between the incident angle of light and the interference characteristic of the cholesteric liquid crystal. The interference wavelength region of the cholesteric liquid crystal is a different region when the light is vertically incident as shown in FIG. 3A and when the light is obliquely incident as shown in FIG. That is, FIG.
As shown in (c), the interference wavelength region 301 at the time of vertical incidence
, The interference wavelength region 302 is shifted to the short wavelength side under the condition that light is obliquely incident. Therefore, the interference wavelength region may be wide on the long wavelength side so that the emission spectrum 303 is included in the interference wavelength region even for obliquely incident light.

The peak wavelength of the emission spectrum of the light source is different from the short wavelength side interference edge wavelength of the cholesteric liquid crystal by 2
The difference 208 from the interference edge wavelength on the longer wavelength side than 07 may be increased.

FIG. 4 is a diagram showing a modified example of the embodiment of FIG. 1 in which a phase converting means is provided on the side opposite to the light source of the polarization separating means and its optical system. In this illuminating device illustrated in FIG. 4A, a quarter wavelength film made of PVA is used as a phase conversion means by being attached to a glass substrate opposite to the light source holding the cholesteric liquid crystal sheet. Linearly polarized light can be extracted by arranging the phase conversion means after the polarized light separation means. The phase conversion means may adjust the sticking direction according to the azimuth of the linearly polarized light to be taken out.
FIG. 4B shows the relationship between the optical system of this lighting device and the polarization.

Non-polarized light emitted from the light source 401 (N in the figure)
The light source light enters the polarized light separating unit 402 and has a clockwise polarity (C +) when viewed on the transmission side, that is, when facing the light.
And circularly polarized light of counterclockwise (C-).
Here, the clockwise circularly polarized light is the first circularly polarized light and the counterclockwise circularly polarized light is the second circularly polarized light, but the opposite case is exactly the same.

The second circularly polarized light (C-) is reflected and returned to the light source side, but the polarity of the circularly polarized light is reversed (C) by the polarization conversion means 403 such as the light source surface, the reflector, the glass interface, and the mirror surface.
+) And becomes the light transmitted through the polarized light separating means. Circularly polarized light with uniform polarity is converted into linearly polarized light (S in the figure) when passing through the phase conversion means 404.

FIG. 5 is a diagram schematically showing an example of an illuminating device further including a second light guide means after the polarization conversion means and the phase conversion means.

A light source 501, a reflector 502, a polarized light separating means 503 composed of a cholesteric liquid crystal sheet, and a PVA.
Linearly polarized light is emitted to the light guide plate 506 side by the phase conversion means 504 made of a quarter wavelength film. Further, an auxiliary light guide plate 505 as shown in FIG. 9 described later is arranged between the light source and the polarized light separating means as a part of the first light guide means.

The second light guide means is mainly composed of a PMMA light guide plate 506, a specular reflection sheet 507 produced by aluminum vapor deposition, and a prism sheet 508. The linearly polarized light incident from the end surface of the light guide plate 506 proceeds while undergoing total reflection at the interface of the light guide plate. In this case, the phase converting means 504 is arranged so that the vibrating surface of the linearly polarized light satisfies the condition of the S-polarized light incident on the reflecting surface. Therefore, the vibration plane of the linearly polarized light does not rotate or depolarize in the light guide plate 506. Further, since the birefringence of the light guide plate 506 is so small as to be negligible, depolarization due to traveling in the light guide plate 506 does not occur and the polarization state of light is preserved.

The light guide plate 506 is provided with a V-shaped groove 509 to form an aluminum reflecting surface. When reflected at this portion, the reflection angle changes and the condition for total reflection deviates, so that light is emitted from the light guide plate 506. The V-shaped groove 509 is also formed so that the S-polarized light enters the vibration plane of the linearly polarized light, so that the polarization component is maintained. Therefore, the light emitted from the light source can be emitted from the upper main surface of the light guide plate as linearly polarized light having a uniform vibrating surface with almost no loss.

A prism sheet 508 may be provided to collect the light emitted from the light guide plate 506 and improve the brightness. Further, the number of prism sheets 508 may be two instead of one.

The V-shaped groove 509 of the light guide plate 506 may be sparse on the side close to the light source and dense on the side far from the light source in order to make the brightness of the emitted light uniform. The same effect can be obtained even if the aluminum reflection surface is not formed in the V-shaped groove 509 and the light is once emitted to the lower side of the light guide plate and reflected by the specular reflection sheet 507. Further, the reflection angle may be changed by providing a V-shaped projection instead of the V-shaped groove 509. Further, by providing the phase conversion means 509 such as a 1/2 wavelength film, the vibration plane of the linearly polarized light can be changed.

FIG. 6 is a view showing an example of an illuminating device provided with a light guide plate between a light source and a polarization converting means. In the case of such an arrangement, a portion corresponding to the second light guide unit in the lighting device shown in FIG. 5, that is, the light guide plate 601,
The specular reflection sheet 602 similarly constitutes a first light guide unit or a polarization conversion unit together with the reflector 603, for example. In the illumination device shown in FIG. 6, the light guide plate 60 is provided with the polarization separation means 604 made of a cholesteric liquid crystal sheet.
1 is provided on the entire main surface on the upper side. The structure of the light guide plate 601 is the same as that of the embodiment of FIG.

The non-polarized light (N in the figure) emitted from the light source 605 is reflected directly or by the reflector 603, and the light guide plate 6 is obtained.
The light enters from the end face 01 and travels in the light guide plate 501 by total reflection. This light is emitted into the light guide plate 601 or the light guide plate 601.
The light is reflected by the reflection surface of the V-shaped groove 606 formed on the lower side, is emitted from the light guide plate 601, and is incident on the polarization separation unit 604.

The unpolarized light source light that has entered the polarized light separating means 604 is separated into first circularly polarized light and second circularly polarized light,
The first circularly polarized light passes through the polarized light separating means 604 and is emitted to the side opposite to the light guide plate. The second circularly polarized light (C- in the figure) is reflected toward the light guide plate 601, passes through the light guide plate 601, and is reflected by the specular reflection sheet 602 formed by aluminum vapor deposition. At this time, the second circularly polarized light is converted into the first circularly polarized light and becomes the light transmitted through the polarized light separating means. Therefore, almost all of the light emitted from the light source is emitted from the polarization splitting means 604 as the first circularly polarized light.

For example, 1/4 is provided after the polarization separation means 604.
As described above, linearly polarized light can be extracted by providing a phase conversion means such as a wavelength film.

Before and after the polarized light separating means 604, for example, first or second frosted glass, holographic optical element, prism sheet, auxiliary light guide plate, microlens, holographic lens array, AR coat film, or the like.
It may be provided as a part of the light guiding means.

FIG. 7 shows a modification of the illumination device shown in FIG. 6 in which the present invention is applied to a direct type illumination device. A light source 702 and a reflector 703 are provided below the light guide plate 701. If an auxiliary light guide plate as shown in FIG. 9 is used as the light guide plate, it is possible to efficiently guide light to the polarization splitting means 704 and convert the polarity of circularly polarized light.

FIG. 8 is a sectional view schematically showing an example of an auxiliary light guide plate which functions as a light guide means or a polarization conversion means. The auxiliary light guide plate 801 has an aluminum vapor deposition reflection surface 8
02 are arranged periodically, and diffused light from the light source side is emitted while being repeatedly reflected by the reflecting surface 802, and is collimated by the prismatic sheet 803 to be polarized light separating means 804.
Incident on.

FIG. 9 is a sectional view schematically showing another example of the auxiliary light guide plate. The auxiliary light guide plate 901 is a transparent light guide 90.
2 and the mirror surface 903. The light traveling through the auxiliary light guide is collimated by the protrusion 904,
It is incident on the polarized light separating means 905. On the other hand, the polarized light separating means 9
The second circularly polarized light reflected from 05 is reflected again on the mirror surface 903, and is converted into the first circularly polarized light at this time. By providing the mirror surface 903 in this way, light is not irregularly reflected and can be efficiently guided to the polarization splitting means 905.

FIG. 10 is a sectional view schematically showing another example of the auxiliary light guide plate. The auxiliary light guide plate 1001 is formed at an angle such that multiple reflection occurs due to total reflection, and diffused light from the light source is condensed by total reflection or refracted at an angle outside total reflection to be parallel light. . In this case, since there is no specular reflection, the light source light can be guided to the polarization separation unit side 1002 with almost no light loss due to multiple reflection.

FIG. 11 is a sectional view schematically showing still another example of the auxiliary light guide plate.

A plurality of cylindrical holes 1102 having different diameters are formed in the auxiliary light guide plate 1101, and a reflecting surface 1103 is formed on the light emitting side. The diffused light from the light source travels while causing total reflection or refraction by using the cylindrical hole 1102 as a reflection interface. By optimizing the size and shape of the hole, the light can be efficiently incident on the polarized light separating means 1104 from the portion other than the portion where the reflecting surface 1103 is provided. The light reflected from the polarization splitting means 1104 has a reflecting surface 1103.
The second circularly polarized light can be efficiently converted into the first circularly polarized light because it is specularly reflected by.

FIG. 12 is a diagram showing the relationship between the incident angle of light on the polarization splitting means and the degree of polarization. The degree of polarization decreases as the incident angle of light increases, that is, the first circularly polarized light and the second circularly polarized light
The performance of separating the circularly polarized light deteriorates. Therefore, by providing the auxiliary light guide plate as described above so that the light is incident at a small incident angle, the light utilization rate becomes high and the brightness of the illuminating device is improved.

FIG. 13 is a diagram showing the polarization splitting ability of the polarization splitting means with and without the use of the auxiliary light guide plate together with the polarization splitting means.

FIG. 14 shows a lighting device 1 having an auxiliary light guide plate.
It is a figure which shows an example schematically. In order to fully exhibit the function of the polarization splitting means 1401, an auxiliary light guide plate 1402 functioning as a light guide means or a polarization converting means is provided on the light incident side of the polarization splitting means 1401. The polarized light separating means 1401 is connected to the light source 1403 and the reflector 1404.
Of the lighting device provided between the light guide plate 1405 and the light guide plate 1405.
An auxiliary light guide plate is arranged between the light guide plate 03 and the polarization splitting means 1401.

FIG. 15 shows the polarization splitting means 1501 as the light guide plate 1.
The light guide plate 15 of the illumination device provided on the entire light emitting surface of 502.
02 and the polarization separation means 1501 between the auxiliary light guide plate 150.
3 are arranged.

The illumination device described above can be widely applied to an optical system using polarized light, including a polarization microscope. For example, it can be applied to an optical system of a liquid crystal display device or a projection type display device.

FIG. 16 is a sectional view schematically showing an example of the liquid crystal display device of the present invention. This liquid crystal display device has polarizing plates 160 on the light incident side and the light emitting side of the liquid crystal layer 1601, respectively.
2, a liquid crystal panel 1604 having 1603, and a light source 16
05, a plurality of cholesteric liquid crystal sheets 1606 which are polarization separation means, a circular polarization conversion means 1607, an auxiliary light guide plate 1608, a PVA1 / 4 wavelength film 1609 which is a phase conversion means, and a vibration plane conversion means for linearly polarized light. It is provided with a certain PVA 1/2 wavelength film 1610 and a light guide plate 1611, a specular reflection sheet 1612, and a prism sheet 1613 as second light guide means for guiding the light transmitted through the polarized light separating means to the liquid crystal panel. Further, although the liquid crystal operation mode of this liquid crystal display device is TN, it may be applied to a liquid crystal display device using another operation mode.

The basic structure of the portion of the liquid crystal display device corresponding to the lighting device is the same as that of the above-mentioned lighting devices. That is, the light source light emitted from the light source becomes the first circularly polarized light having the same polarity by the first light guide unit, the reflector 1614 which is the polarization conversion unit, the auxiliary light guide plate 1608 and the cholesteric liquid crystal sheet 1606.

The first circularly polarized light with uniform polarity is PVA1 /
It is converted into linearly polarized light (S in the figure) by the four-wavelength film 1609 and enters the PMMA light guide plate 1611. At this time, a quarter-wave film is arranged so that the polarization direction is S-polarized incidence on the upper and lower total reflection surfaces of the light guide plate. A specular reflection sheet 1612 made by vapor deposition of aluminum is provided below the lower main surface of the light guide plate, and a prism sheet 1613 is provided above the upper main surface.

The PVA 1/2 wavelength film 1610 which is the vibration surface converting means is arranged between the prism sheet 1613 and the liquid crystal panel 1604. The vibrating surface converting means is a means for matching the vibrating surface of the linearly polarized light obtained by the phase converting means with the light transmission axis of the incident side polarizing plate of the liquid crystal panel. It may be arranged at any position. Moreover, you may make it arrange | position a plurality.

The linearly polarized light incident on the light guide plate 1611 proceeds while undergoing total reflection at the interface of the light guide plate 1611. However, since the vibrating surface of the linearly polarized light is the condition of S polarized light incidence on the reflecting surface, the vibrating surface is rotated. , Depolarization does not occur. In addition, since the birefringence of the light guide plate 1611 is so small that it can be ignored, the polarization state of light is preserved without depolarization caused by traveling in the light guide plate 1611.

The light emitted from the light guide plate 1611 is adjusted in its emission direction by the prism sheet 1613 and PVA1 / 2.
It is incident on the wavelength film 1610.

Light guide plate 1611 and prism sheet 1613
In this case, the vibration direction of the linearly polarized light emitted from the liquid crystal panel 1
It is a direction perpendicular to the upper and lower sides of the display screen 604. Since the polarizing plate transmission axis of the liquid crystal panel 1604 is inclined by 45 ° from the vertical direction of the display screen, the polarization direction is set to 45 by the ½ wavelength film 1610 in order to match the vibration direction of the linearly polarized light with the polarizing plate transmission axis. Rotation (S in the figure
+ 45 °) and guide it to the incident side polarization plate 1602 of the liquid crystal panel. The vibrating direction of the linearly polarized light to be rotated is not limited to 45 °, and the ½ wavelength film may be arranged so as to match the transmission axis of the polarizing plate of the liquid crystal panel.

The prism sheet 1613 may be arranged in a direction rotated by 90 ° from the direction shown in FIG. 16 when the incident light is S-polarized light. In the case of P-polarized light, the orientation shown in FIG. 16 is preferable.

The order of the prism sheet 1613 and the half-wave film 1610 may be exchanged.

With such a structure, an effective illumination light can be obtained without increasing the size of the device and without absorbing a light component which was conventionally absorbed by the incident side polarization plate of the liquid crystal panel and was not used as illumination light. Since the liquid crystal display device can be used, the liquid crystal display device has high brightness and high light utilization efficiency. In addition, power consumption is also reduced.

FIG. 17 shows the relationship between the arrangement of the optical components of the optical system corresponding to the liquid crystal display device illustrated in FIG. 16 and the polarization. The polarized light separating means 1702 exemplified here is one that transmits the first circularly polarized light and reflects the second circularly polarized light.

Non-polarized (N in the figure) light source light emitted from the light source 1701 is incident on the polarization separation means 1702 and is a circle having a clockwise (C +) polarity when viewed on the transmission side, that is, when facing the light. It is separated into polarized light and counterclockwise (C-) circularly polarized light. Here, the clockwise circularly polarized light is the first circularly polarized light and the counterclockwise circularly polarized light is the second circularly polarized light, but the opposite case is exactly the same.

The second circularly polarized light (C-) is reflected and returns to the light source side, but the polarity of the circularly polarized light is reversed (C) by the polarization conversion means 1703 such as the light source surface, the reflector, the glass interface, and the mirror surface.
+) And becomes the light transmitted through the polarized light separating means. As described above, these polarization conversion means 1702 may also be used as the first light guide means.

Circularly polarized light of uniform polarity is phase conversion means 17
When transmitted through 04, it is converted into linearly polarized light (S in the figure).
The relationship between the fast axis (F) and the incident circularly polarized light (C +) and the outgoing linearly polarized light (S) at that time is as shown in FIG.

In the liquid crystal display device illustrated in FIG. 16, for example, the linearly polarized light is incident on the vibration surface conversion means 1705 while changing the emission direction while maintaining the polarization state on the reflection surface of the light guide plate which is a part of the second light guide means. To do. Polarizing plate 1 for liquid crystal panel
The transmission axis (T) of 706 is S as shown in FIG.
When it is rotated by 45 ° from the polarization direction,
As shown in 0, if the fast axis of the vibrating surface conversion means is 22.5 ° that bisects the angle of the linearly polarized light component with the polarizing plate transmission axis, the polarizing plate transmitted light (S + 45 °) is obtained.

The polarities of the circularly polarized light transmitted through the polarized light separating means 1702 may be the same as the polarities of the polarized light reflected or transmitted, and the clockwise circularly polarized light (first circularly polarized light).
May be reflected, and counterclockwise circularly polarized light (second circularly polarized light) may be transmitted. Further, the linearly polarized light incident on the light guide plate may be P polarized light instead of S polarized light. The fast axes of the quarter-wave film and the half-wave film may be adjusted according to these conditions so that they finally pass through the transmission axis of the polarizing plate of the liquid crystal panel.

FIG. 21 is a diagram for explaining the structure of another example of the liquid crystal display device of the present invention. In this liquid crystal display device, the polarized light separating means is arranged on the entire upper main surface of the light guide plate. Also,
Although the operation mode of the liquid crystal is STN, it may be applied to a liquid crystal display device using another operation mode.

Cold cathode fluorescent tube 2101 reflector 2102
Non-polarized light source light emitted from the light source part (N in the figure)
Travels in the light guide plate 2103 by total reflection. A plurality of cholesteric liquid crystal sheets enter the polarization separation means 2104 sandwiched by the transparent film substrates due to reflection at the V-shaped groove 2104 of the light guide plate.

The non-polarized light source light incident on the polarized light separating means 2104 is divided into the first circularly polarized light and the second circularly polarized light having different polarities.
It is separated into two circularly polarized light components. Reflected light component (C- in the figure)
The second circularly polarized light passing through the light guide plate 2103 is reflected by the aluminum vapor deposition reflection surface 2105 so that the polarization component is inverted (C +) and becomes the light transmitted by the polarized light separating means.

The circularly polarized light component transmitted through the polarized light separating means is converted into linearly polarized light which coincides with the polarizing plate transmission axis of the incident side polarizing plate 2107 of the liquid crystal panel 2106 by the quarter wavelength film 2105 which is the phase converting means. , Enters the incident side polarization plate 2107 of the liquid crystal panel. Therefore, it is possible to use half the components of the light source light that could not be used until now, and the liquid crystal display device has a high light utilization rate and a high luminance and a low power consumption.

Alternatively, the light may be condensed by the prism sheet 2108 and then incident on the incident side polarization plate 2107 of the liquid crystal panel 2106. In addition, the prism sheet 21
A plurality of 07 may be used. Further, it may be arranged before the polarization separation means 2104. In this case, the prism sheet constitutes a part of the first light guide means.

FIG. 22 is a sectional view for schematically explaining the constitution of another example of the liquid crystal display device of the present invention. In this liquid crystal display device, the V-shaped groove 22 provided below the light guide plate 2201 in the liquid crystal display device illustrated in FIG.
02 is provided on the upper surface side. This V-shaped groove 22
02 may be a V-shaped projection.

In the case of such a structure, it is not necessary to use a metal reflection sheet, and the light guide plate 22 is out of the condition of total reflection.
The light emitted from 01 does not suffer the loss due to metal reflection. Therefore, light can be emitted with higher efficiency. However, most of the light emitted from the light guide plate 2201 is a component emitted in an oblique direction, so that the maximum luminance direction deviates from the screen vertical direction as shown in FIG. By newly adding a HOE (holographic optical element) 2203, the maximum brightness direction and the vertical direction of the screen are made to coincide with each other as shown while keeping the polarization.

The HOE 2203 may be used not only in the liquid crystal display device illustrated in FIG. 22 but also in other liquid crystal display devices and lighting devices as the second light guide means for the purpose of optimizing the luminance direction. Further, the position where the HOE 2203 is provided may be replaced with the prism sheet 2204 and the half-wave film 2205.

FIG. 24 is a sectional view schematically showing the structure of still another example of the liquid crystal display device of the present invention. In this liquid crystal display device, a diffusing plate is used as a part of the second light guide means for the purpose of improving the viewing angle of the liquid crystal panel 2401. As the diffusion plate, for example, the HOE diffusion plate 2
You may make it use 402.

In this liquid crystal display device, the light emitted from the ½ wavelength film 2403 is diffused by the HOE diffusion plate 2402 in the oblique direction of the display screen while maintaining the polarization state. Therefore, as shown in FIG.
The screen brightness distribution after passing 1 is the HOE diffusion plate 240
The luminance in the oblique direction is made uniform as compared with the state in which 2 is not provided. Further, since the polarization state of the emitted light can be preserved, the light absorption by the polarizing plate of the liquid crystal panel 2401 is less than that in the case of using a normal white diffuser, that is, the brightness of the entire screen is improved. can do.

The diffusion sheet is used not only in the liquid crystal display device illustrated in FIG. 24 but also in other liquid crystal display devices and lighting devices as the second light guide means for the purpose of optimizing the luminance direction. Good. Further, the prism sheet 2404 and the ½ wavelength film 2403 may be replaced with each other.

[0112]

As described above, according to the illumination device of the present invention, the light from the light source can be efficiently emitted as circularly polarized light with uniform polarity. Further, the light from the light source can be efficiently emitted as linearly polarized light having a uniform vibrating surface.

According to the liquid crystal display device of the present invention, the utilization factor of the light source light can be improved and the display brightness can be increased without increasing the size of the device. In addition, power consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing an example of a lighting device of the present invention.

FIG. 2 is a diagram showing a relationship between optical characteristics of a light source and a polarization splitting means.

FIG. 3 is a diagram showing a relationship between an incident angle of light and an interference characteristic of a cholesteric liquid crystal.

FIG. 4 is a diagram schematically showing an example of an illumination device of the present invention and its optical system.

FIG. 5 is a sectional view schematically showing an example of a lighting device of the present invention.

FIG. 6 is a sectional view schematically showing an example of a lighting device of the present invention.

FIG. 7 is a sectional view schematically showing an example of a lighting device of the present invention.

FIG. 8 is a sectional view schematically showing an example of an auxiliary light guide plate.

FIG. 9 is a sectional view schematically showing an example of an auxiliary light guide plate.

FIG. 10 is a sectional view schematically showing an example of an auxiliary light guide plate.

FIG. 11 is a sectional view schematically showing an example of an auxiliary light guide plate.

FIG. 12 is a diagram showing a relationship between an incident angle to a polarized light separating means and a polarized light separating ability.

FIG. 13 is a diagram showing the relationship between the presence / absence of an auxiliary light guide plate and the polarization separation ability.

FIG. 14 is a cross-sectional view showing an example of a lighting device including an auxiliary light guide plate.

FIG. 15 is a sectional view showing an example of a lighting device including an auxiliary light guide plate.

FIG. 16 is a sectional view schematically showing a liquid crystal display device of the present invention.

17 is a diagram schematically showing the relationship between the optical system and polarized light of the liquid crystal display device of FIG.

FIG. 18 is a diagram schematically showing the state of polarization.

FIG. 19 is a diagram schematically showing the state of polarized light.

FIG. 20 is a diagram schematically showing the state of polarization.

FIG. 21 is a sectional view schematically showing an example of a liquid crystal display device of the present invention.

FIG. 22 is a sectional view schematically showing an example of a liquid crystal display device of the present invention.

FIG. 23 is a diagram showing the relationship between the presence or absence of HOE and the maximum luminance direction of emitted light.

FIG. 24 is a sectional view schematically showing an example of a liquid crystal display device of the present invention.

FIG. 25 is a diagram showing the relationship between the presence or absence of a diffusion plate and the screen brightness distribution.

FIG. 26 is a perspective view showing an example of an edge light type illumination device.

FIG. 27 is a perspective view showing an example of a direct type illumination device.

[Explanation of symbols]

101 ... Cold cathode fluorescent tube, 102 ... Reflector, 10
3, 104, 105 ... Cholesteric liquid crystal sheet 106, 107 ... Glass substrate, 501 ... Light source, 50
2 ... Reflector 503 ... Polarization separation means, 504 ... Phase conversion means, 5
05 ... auxiliary light guide plate 506 ... light guide plate, 507 ... specular reflection sheet, 508
...... Prism sheet 509 V-shaped groove 601, light guide plate 602 specular reflection sheet 603 reflector 604 polarization splitting means 70
1 ... Light guide plate 702 ... Light source, 703 ... Reflector, 801 ... Auxiliary light guide plate 802 ... Aluminum vapor deposition reflection surface, 803 ... Prism sheet 901 ... Auxiliary light guide plate, 902 ... Light guide body, 903 ......
Mirror surface, 904 ... Projection portion 905 ... Polarization separating means, 1601 ... Liquid crystal layer, 160
2, 1603 ... Polarizing plate 1604 ... Liquid crystal panel, 1605 ... Light source, 1606
...... Polarization separation means 1607 ...... Polarization conversion means 1608 ...... Auxiliary light guide plate 1609 ...... 1/4 wavelength film, 1610 ...... 1/2
Wavelength film 1611 ... Light guide plate, 1612 ... Specular reflection sheet 1613 ... Prism sheet, 1614 ... Reflector, 1701 ... Light source 1702 ... Polarization separation means 1703 ... Polarization conversion means 1704 ... Phase conversion means, 1705 ...... Vibration surface conversion means 1706 Incident side polarization plate 2201 ...... Light guide plate 2202
V-shaped groove 2203 holographic optical element 2204
Prism sheet 2205 …… 1/2 wavelength film 2401 …… Liquid crystal panel 2402 …… HOE diffuser plate, 2403 …… 1/2 wavelength film 2404 …… Prism sheet

Claims (7)

[Claims] 1. A light source, and a first circularly polarized light and a second circularly polarized light of which light source light from the light source is oscillated in opposite directions of rotation, and the first circularly polarized light is transmitted through the second circularly polarized light. Polarized light separating means by a helical structure molecule that separates the circularly polarized light by reflecting, circularly polarized light converting means for converting the second circularly polarized light into the first circularly polarized light, the source light or the first circularly polarized light An illuminating device comprising: a light guide means for making polarized light incident on the polarized light separating means at a predetermined incident angle; and a phase converting means for converting the first circularly polarized light transmitted through the polarized light separating means into linearly polarized light. . 2. The light source, and the first circularly polarized light and the second circularly polarized light of which the light source light is emitted from the light source, are transmitted through the first circularly polarized light and the second circularly polarized light whose vibration directions are opposite to each other. Polarized light separating means by a helical structure molecule that separates the circularly polarized light by reflecting, circularly polarized light converting means for converting the second circularly polarized light into the first circularly polarized light, the source light or the first circularly polarized light First light guide means for making polarized light incident on the polarized light separating means at a predetermined incident angle, phase conversion means for converting the first circularly polarized light transmitted through the polarized light separating means into linearly polarized light, and transmitting through the polarized light separating means. The second that guides the emitted light in a predetermined direction
An illuminating device comprising the light guiding means of. 3. The polarization splitting means is at least 420-
450nm, 520-570nm, 590-630nm
3. The illuminating device according to claim 1, wherein the illuminating device has an interference wavelength region of circularly polarized light selective reflection. 4. The illuminating device according to claim 1, wherein the main emission spectrum of the light source is included in an interference wavelength region of the polarized light separating means. 5. The main emission spectrum of the light source is included between the center wavelength of the interference wavelength region of the polarization separation means and the short wavelength side interference edge wavelength. Illumination device described. 6. A liquid crystal panel having a liquid crystal layer and a polarizing plate, a light source, and light source light from the light source into a first circularly polarized light and a second circularly polarized light whose vibrating surfaces have opposite rotation directions. Polarization separation means by a helical structure molecule that separates by transmitting the first circularly polarized light and reflecting the second circularly polarized light; and circularly polarized light conversion means for converting the second circularly polarized light into the first circularly polarized light. A first light guide means for causing the light source light or the first circularly polarized light to enter the polarization splitting means at a predetermined incident angle; and a first circularly polarized light transmitted through the polarization splitting means to be linearly polarized light. A liquid crystal display device comprising: phase conversion means; and second light guide means for guiding the linearly polarized light to the liquid crystal panel while maintaining the linearly polarized light. 7. A liquid crystal panel having a liquid crystal layer and a polarizing plate, a light source, and light source light from the light source into a first circularly polarized light and a second circularly polarized light whose vibrating surfaces have opposite rotation directions. Polarization separation means by a helical structure molecule that separates by transmitting the first circularly polarized light and reflecting the second circularly polarized light; and circularly polarized light conversion means for converting the second circularly polarized light into the first circularly polarized light. A first light guide means for causing the light source light or the first circularly polarized light to enter the polarization splitting means at a predetermined incident angle; and a first circularly polarized light transmitted through the polarization splitting means to be linearly polarized light. Phase conversion means, vibration plane conversion means for converting the vibration surface of the linearly polarized light so as to pass through the light incident side polarization plate of the liquid crystal panel, and second light guide means for guiding the linearly polarized light to the liquid crystal panel. A liquid crystal display device comprising: