JPH0588142A - Liquid crystal panel and liquid crystal display device using the same - Google Patents

Abstract

PURPOSE:To provide the liquid crystal panel which makes a high-brightness display and has a high contrast. CONSTITUTION:On a counter electrode substrate 11, a two-dimensional diffraction grating is formed on the surface in contact with macromolecule dispersed liquid crystal 17. The refractive index of projection parts 13 of the diffraction grating is equalized to the refractive index of the liquid crystal 17 when a voltage is applied between a counter electrode 16 and picture element electrodes 15. When the voltage is not applied between the counter electrode 16 and picture element electrodes 15, light made incident on the liquid crystal panel is refracted because of the refractive index difference between the projection parts 13 and liquid crystal 17 and scattered by the liquid crystal 17. When the voltage is applied, the refractive index difference is eliminated, so the light travels straight. The liquid crystal panel is used for the viewfinder, etc., of a liquid crystal projection type television, a video camera, etc. Therefore, when no polarizing plate is used, a high-brightness image can be displayed. Further, the high contrast is provided by the diffraction effect and the scattering effect of the liquid crystal 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION A liquid crystal display device for enlarging and projecting an image displayed on a liquid crystal panel of the present invention on a screen (hereinafter referred to as "
The present invention relates to a liquid crystal display device (hereinafter referred to as a viewfinder) and a liquid crystal display device used for displaying captured images with a video camera or the like, and a liquid crystal panel used for the liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device using a liquid crystal panel is C
Research and development are actively conducted because the possibility of weight reduction and thickness reduction is higher than that of a display device using an RT. In recent years, a twist nematic mode (hereinafter, referred to as TN mode) liquid crystal display device in which the optical rotatory power of liquid crystal is applied to image display has been put into practical use, and is used for a portable pocket TV, a viewfinder of a video camera, and the like. ..

However, the liquid crystal display device has many problems such as difficulty in increasing the screen size. Therefore, in recent years, research and development of a liquid crystal projection television, which enlarges and projects a display image of a small liquid crystal panel by a projection lens or the like to obtain a large display image, has been actively conducted.

FIG. 15 is an equivalent circuit diagram of the liquid crystal panel. G _{1 to} G _m are gate signal lines, one end of which is connected to the gate drive IC 151. S _{1 to} S _n are source signal lines, one end of which is connected to the source drive IC 152. Each pixel has a TFT 153 for applying a signal to the pixel electrode, and an additional capacitor 154 for holding a signal is formed. 1
Reference numeral 55 denotes a liquid crystal sandwiched between the pixel electrode and the counter electrode.

A conventional liquid crystal panel will be described below. FIG. 16 is a sectional view of a conventional liquid crystal panel. 1
67 is a black matrix made of chrome,
166 is a counter electrode formed of a transparent electrode such as ITO. The array substrate 162 and the counter electrode substrate 141 have 4 to 6
The TN liquid crystal 163 is held between the substrates while being held at an interval of μm. The periphery of the display area is sealed with a sealing resin (not shown). Reference numeral 164 is a source signal line.

Hereinafter, a conventional method for manufacturing a liquid crystal panel will be described. First, the array substrate 162 and the counter electrode substrate 1
Alignment films 168a and 168b are applied to 61 and subjected to alignment treatment by rubbing. After that, sealing resin (not shown) is left in the periphery of the array substrate 162, leaving an injection port for TN liquid crystal.
Is applied. Moreover, beads for obtaining a uniform liquid crystal film thickness are scattered on the counter electrode substrate 161. Next, the counter electrode substrate 161 and the array substrate 162 are bonded together. After that, the sealing resin is cured by irradiation with ultraviolet rays or heating. Next, the bonded substrates are put in a vacuum chamber, the gap between the array substrate 162 and the counter electrode substrate 161 is evacuated, and then the liquid crystal inlet is immersed in the liquid crystal. After that, when the vacuum in the vacuum chamber is broken, the liquid crystal is injected into the gap through the injection port. Finally, the injection port is sealed and completed.

A liquid crystal projection television will be described below as an example of a conventional liquid crystal display device with reference to the drawings.
FIG. 17 is a configuration diagram of a conventional liquid crystal projection television.
In FIG. 17, 171 is a condensing optical system, 172 is a UVIR cut mirror that transmits infrared rays and ultraviolet rays,
173a is a blue light reflecting dichroic mirror (hereinafter, B
DM), 173b is a green light reflecting dichroic mirror (hereinafter referred to as GDM), 173c is a red light reflecting dichroic mirror (hereinafter referred to as RDM), 174.
a, 174b, 174c, 176a, 176b, 176
Reference numeral c is a polarizing plate, 175a, 175b and 175c are transmissive TN liquid crystal panels, and 177a, 177b and 177c are projection lens systems. It should be noted that components unnecessary for the description are omitted from the drawings.

The operation of the conventional liquid crystal projection television will be described below. First, the white light emitted from the condensing optical system 171 is reflected by the BDM 173a as blue light (hereinafter referred to as B light), and the B light is incident on the polarizing plate 174a. The light transmitted through the BDM 173a is reflected by the GDM 173b as green light (hereinafter, referred to as G light), and then is polarized by the polarizing plate 174.
The red light (hereinafter, referred to as R light) is reflected by the RDM 174c and is incident on the polarizing plate 174c. The polarizing plate transmits only one of the longitudinal wave component and the transverse wave component of each color light, aligns the polarization directions of the light, and irradiates each liquid crystal display device. At this time, 50% or more of the light is absorbed by the polarizing plate, and the brightness of the transmitted light is half or less at the maximum.

Each liquid crystal panel modulates the transmitted light according to a video signal. The modulated light passes through the respective polarizing plates 176a, 176b, 176c according to the degree of modulation, enters the respective projection lens systems 177a, 177b, 177c, and is enlarged and projected on the screen (not shown) by the lens system. ..

[0010]

As is clear from the above description, in a liquid crystal panel using TN liquid crystal, it is necessary to make linearly polarized light incident. Therefore, it is necessary to dispose polarizing plates before and after the liquid crystal panel. Theoretically, this polarizing plate absorbs 50% or more of light. Therefore,
There is a problem that only a low brightness screen can be obtained when the image is enlarged and projected on the screen. In order to solve this problem, a polymer dispersed liquid crystal is used in the present invention. A liquid crystal panel using polymer-dispersed liquid crystal does not use a polarizing plate, and thus the light utilization efficiency can be made very high.

The polymer-dispersed liquid crystal will be briefly described below. Polymer dispersed liquid crystals are roughly classified into two types depending on the dispersion state of liquid crystals and polymers. One is a type in which liquid crystals in the form of water droplets are dispersed in a polymer. The liquid crystal exists in the polymer in a discontinuous state. Hereinafter, such a liquid crystal will be referred to as a PDLC, and a liquid crystal panel using the liquid crystal will be referred to as a PD liquid crystal panel. The other is a type that has a structure in which a polymer network is stretched around the liquid crystal layer. It looks like a sponge containing liquid crystal. The liquid crystal does not form a water drop but continuously exists. Hereinafter, such a liquid crystal will be referred to as a PNLC, and a liquid crystal panel using the liquid crystal will be referred to as a PN liquid crystal panel. In order to display an image with the above-mentioned two types of liquid crystal panels, light scattering and transmission are controlled.

PDLC utilizes the property that the refractive index differs in the direction in which the liquid crystal is aligned. When no voltage is applied, each water droplet liquid crystal is oriented in an irregular direction. In this state, a difference in refractive index occurs between the polymer and the liquid crystal, and incident light is scattered. When a voltage is applied here, the alignment directions of the liquid crystal are aligned. If the refractive index when the liquid crystal is oriented in a certain direction is matched with the refractive index of the polymer in advance, incident light is transmitted without being scattered.

On the other hand, PNLC uses the irregularity itself of the alignment of liquid crystal molecules. The incident light is scattered in the irregular alignment state, that is, in the state where no voltage is applied.
On the other hand, light is transmitted when a voltage is applied and the array state is made regular. The above description of the movement of the liquid crystal of PDLC and PNLC is merely a model idea. Although the present invention is not limited to one of the PD liquid crystal panel and the PN liquid crystal panel, it is not limited to the PD liquid crystal panel for ease of explanation.
A liquid crystal panel will be described as an example. Further, PDLC and PNLC are collectively referred to as polymer dispersed liquid crystal, and PD liquid crystal panel and PN liquid crystal panel are collectively referred to as polymer dispersed liquid crystal panel. A liquid containing a liquid crystal to be injected into a polymer dispersed liquid crystal panel is generically called a liquid crystal solution, and a state in which a resin component in the liquid crystal solution is polymerized and cured is called a polymer.

Operation of polymer dispersed liquid crystal (FIG. 18)
A brief description will be given using (a) and (b). (Fig. 18 (a)
(B) is an explanatory view of the operation of the polymer dispersed liquid crystal panel. In FIGS. 18A and 18B, 181 is an array substrate, 182 is a pixel electrode, 183 is a counter electrode, 184 is a droplet liquid crystal, 185 is a polymer, and 186 is a counter substrate. A TFT or the like is connected to the pixel electrode 182, and a voltage is applied to the pixel electrode when the TFT is turned on / off to change the liquid crystal alignment direction on the pixel electrode to modulate light. (Fig. 1
As shown in FIG. 8 (a), when no voltage is applied, the water droplet liquid crystals 184 are oriented in irregular directions. In this state, a difference in refractive index occurs between the polymer 185 and the liquid crystal 184, and incident light is scattered. Here (Fig. 18
As shown in (b), when a voltage is applied to the pixel electrode, the liquid crystal is aligned. If the refractive index when the liquid crystal is aligned in a certain direction is matched with the refractive index of the polymer in advance, the incident light is emitted from the array substrate 181 without being scattered.

When it is attempted to construct a high-quality display panel using polymer-dispersed liquid crystal, the amount of light transmitted in the scattered state is
It is necessary to increase the ratio of the amount of transmitted light in the transmitted state (hereinafter referred to as contrast). If the contrast is low, the gradation display characteristics deteriorate. A liquid crystal projection television needs a contrast of 100 or more. The maximum transmittance of the polymer-dispersed liquid crystal panel is regulated by the ITO film or the like of the counter electrode, but it is about 80 to 85%. However, the light transmission amount at the time of scattering is also large. In order to increase the contrast, it is necessary to reduce the amount of transmission in the scattered state (hereinafter referred to as scattering transmittance). In order to reduce the amount of transmission in the scattering state, it is necessary to increase the film thickness of the liquid crystal layer, but if the thickness is increased, the applied voltage for setting the transmission state becomes high and the liquid crystal cannot be driven. From the above, although the brightness can be increased by using the polymer-dispersed liquid crystal, the contrast cannot be increased, and it has been difficult to construct a good liquid crystal panel and a liquid crystal projection television.

The video camera is required to be compact and lightweight in terms of portability and operability. Therefore, introduction of a liquid crystal display device as a viewfinder display is expected. However, the power consumption of the viewfinder using the liquid crystal display device is quite large at present. For example, the power consumption of a viewfinder using a TN liquid crystal display device is about 0.1 W for a liquid crystal display device and about 1.0 W for a light source. The video camera has a limited battery capacity to ensure compactness and lightness, and when the viewfinder consumes a large amount of power,
This is a big problem because the continuous use time becomes short.

The following are possible causes of the large power consumption of the TN liquid crystal display device. As aforementioned,
A liquid crystal panel using TN liquid crystal needs polarizing plates on the incident side and the emitting side, and the total transmittance of these two polarizing plates is about 3
It becomes 0%. Further, the light box needs to be a surface light source with little unevenness in brightness, and for that reason, a diffusion plate is arranged between the TN liquid crystal panel and the light box. When a diffuser plate having a low light diffusion rate is used, a light emission pattern of a fluorescent tube in a light box appears, which is visible through the display screen of the liquid crystal panel, which deteriorates the display quality. Therefore, a diffuser plate having a high diffusivity is used, but generally, if the diffusivity is increased, the transmittance is lowered, and if an attempt is made to obtain a required brightness, power consumption of the light source is increased. Due to the above, the power consumption was large and the video camera could not be used continuously.

[0018]

When a TN liquid crystal is used, 50% or more of light is absorbed by a polarizing plate, so that the light utilization rate is low and high-luminance image display cannot be performed. In addition, power consumption also increases.

The liquid crystal panel of the present invention uses polymer dispersed liquid crystal as the liquid crystal. Further, a two-dimensional diffraction grating is formed on the counter electrode substrate. The diffraction grating is formed by processing the counter electrode substrate.

The liquid crystal projection television of the present invention is constructed using the liquid crystal panel of the present invention. Originally, polymer-dispersed liquid crystal panels had poor scattering properties. However, a diffraction grating is formed in the liquid crystal panel of the present invention, and the contrast is improved by this diffraction effect and the scattering effect of the polymer dispersed liquid crystal.

Further, the viewfinder of the present invention uses a light emitting element for emitting light in a minute region as a light source, and further, a condenser lens for condensing light emitted from the light source and converting it into parallel light, and a condenser lens. The liquid crystal panel for modulating the generated light is provided. The liquid crystal panel of the present invention is used as the liquid crystal panel.

[0022]

In the liquid crystal panel of the present invention, the glass used for the counter electrode substrate is etched to form a two-dimensional diffraction grating. ITO or the like is deposited on the diffraction grating to form a counter electrode. The height of the diffraction grating is 1 to 5 μm. The convex part of the diffraction grating is 3
In the case of μm, the ITO of the concave portion and the ITO of the convex portion of the diffraction grating are electrically insulated, but in the case of the two-dimensional diffraction grating, the proportion of the convex portion is 1/4 of the concave portion. Therefore, there is no problem in driving the liquid crystal by using the ITO in the recess and the counter electrode.

Polymer dispersed liquid crystal is sandwiched between the counter electrode substrate on which the diffraction grating is formed and the array substrate on which the pixel electrodes are formed. The refractive index n _p of the polymer of the polymer dispersed liquid crystal and the ordinary refractive index of the liquid crystal are n _o . Usually, in the polymer dispersed liquid crystal, the material used is set so that n _p = n _o . Further, when a voltage is applied to the liquid crystal layer, the liquid crystal is aligned (hereinafter referred to as an on state) and is in a transmissive state. The on-state refractive index n _on
Becomes n _o . Conversely, when no voltage is applied to the liquid crystal,
The liquid crystal is in a random alignment state (hereinafter referred to as an off state) and is in a scattering state. Assuming that the polymer ratio is small, the refractive index n _off at this time is approximately (2n _o + n _e ) / 3.
Becomes LCD n _o is a number material 1.52 to 1.54, also the material of the diffraction grating, i.e. the refractive index of the glass substrate n
Most of the _g are 1.52 to 1.54. Both materials can be selected easily. Also, the mechanical strength of the diffraction grating is high. In the on state, n _g = n _o , and the diffraction grating is in a disappeared state. Therefore, the incident light on the liquid crystal panel goes straight on. Since n _g ≠ n _{off in the} off state, a refractive index difference is generated between the diffraction grating and the liquid crystal layer, and the incident light to the liquid crystal panel is diffracted and scattered by the liquid crystal layer. Therefore, the contrast is improved.

In the viewfinder, the position of the observer's pupil is almost fixed by the eyepiece ring. Even when the eyepiece ring is not used, a wide viewing angle is not required because the display screen is small. In other words, when a liquid crystal display device is used as a viewfinder, the light source arranged behind it may have a narrow directivity. When a fluorescent backlight is used as a light source, only light that travels within a minute solid angle in a certain direction from a region that is approximately the same size as the display region of the liquid crystal display device is used, and light that travels in other directions is not used.

Therefore, in the present invention, a light source having a small light-emitting body is used, and light emitted from the light-emitting body in a wide solid angle is converted into near-parallel light by a condenser lens. This way
The light emitted from the condenser lens has a narrow directivity, and the narrow directivity is sufficient for use in a viewfinder. If the size of the light-emitting body is small, the power consumption is naturally small.

The condenser lens has no aberration and the transmittance is 100%.
In the case of, the brightness of the light emitter viewed through the condenser lens is equal to the brightness of the light emitter itself. If the maximum transmittance of the liquid crystal display device including the color filter and the polarizing plate is 30%, the transmittance of the condenser lens is 90%, and the brightness required for the viewfinder is 15 [ft-L], the brightness required for the light source. Is about 56
It becomes 0 [ft-L]. In the present invention, as a light emitting element having such a brightness and a small light emitting region, a light emitting tube and an LED (Light Emitting Diode) described later are used.
e) etc. are used.

In the viewfinder of the present invention, a light emitting element having a small light emitting region is used as a light source, and the light emitted from the light emitting element in a wide solid angle is efficiently condensed by the condensing means. The efficiency is higher and the power consumption of the light source is lower than when used.

A liquid crystal display device using a polymer dispersed liquid crystal is
Since no polarizing plate is required, the brightness of the light source for obtaining the required screen brightness is lower than that of a liquid crystal display device using TN liquid crystal. Therefore, the power consumption of the light source can be significantly reduced.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal panel of the present invention will be described below with reference to the drawings. FIG. 3 is a plan view of a counter electrode substrate used in the liquid crystal panel of the present invention. In FIG. 3, 13 is a convex portion of the two-dimensional diffraction grating. Also, 16 is
The counter electrode is made of ITO or the like. The film thickness of the counter electrode 16 is required to be 500 Å or more, but it is preferable that it is thin because it affects the diffraction efficiency and the like. FIGS. 1 and 2 are diagrams in which a liquid crystal panel is constructed using the counter electrode substrate shown in FIG. Note that (FIG. 1) (FIG. 2) is a cross-sectional view of one pixel of the liquid crystal panel, and (FIG. 1) is AA ′ of (FIG. 3).
FIG. 4 is a sectional view taken along line BB ′ of FIG. 2 and FIG. 3. It should be noted that parts not necessary for the explanation are omitted, and the figures are modeled and drawn.

In FIG. 1 and FIG. 2, 11 is a counter electrode base, and 12 is an array substrate. I on the array substrate 12
A pixel electrode 15 made of TO, a source signal line 14, etc. are formed, and a switching element (not shown) for applying an image signal to each pixel electrode is formed on the pixel electrode 15. A thin film transistor (hereinafter referred to as a TFT), a diode, or the like corresponds to the switching element. The pitch of the diffraction grating is 3 to 20 μm, and the range of 5 to 10 μm is preferable when it is used in a liquid crystal projection type television described below. The height of the diffraction grating is 1
~ 6 μm. The shape of the diffraction grating is not limited to the rectangular shape as shown in (FIG. 1), and may be any of trapezoidal shape, sine curve shape, triangular wave shape, and sawtooth wave shape. It is preferable that the height of the diffraction efficiency and the height of the convex portion 13 of the diffraction grating be the lowest, or a rectangular shape. Moreover, the mechanical strength of the diffraction grating was high, and a liquid crystal panel could be formed well.

The arrangement of the two-dimensional diffraction grating is preferably a square arrangement as shown in (FIG. 3). In the arrangement shown in (FIG. 3), the diffraction characteristics were very good also in the horizontal direction, the vertical direction and the oblique direction. The ITO film is provided on the protrusion 13 with the counter electrode 1
When forming 6, the ITO and the counter electrode 1 are vapor-deposited.
No. 6 is not electrically connected because the produced convex portion 13 has a thickness of about 3 μm. Further, the ITO may be removed. However, since the area of the convex portion is ¼ of the entire area, the necessary counter electrode area can be secured, and there is no influence on the driving of the liquid crystal.

The liquid crystal of the polymer dispersed liquid crystal layer 17 is preferably a nematic liquid crystal, a smectic liquid crystal or a cholesteric liquid crystal, and may be a single liquid crystal compound or a mixture of two or more liquid crystal compounds or a substance other than the liquid crystal compound. ..
Of the above-mentioned liquid crystal materials, the cyanbiphenyl nematic liquid crystal is most preferable. The resin material is preferably a transparent polymer, and may be a thermoplastic resin, a thermosetting resin, or a photocurable resin, but it is an ultraviolet curable type from the viewpoint of ease of manufacturing process, separation from the liquid crystal layer, etc. It is preferable to use the above resin. As a specific example, an ultraviolet-curable acrylic resin is exemplified, and a resin containing an acrylic monomer or an acrylic oligomer that is polymerized and cured by ultraviolet irradiation is particularly preferable. By irradiating with ultraviolet rays, these cause a polymerization reaction only in the resin to become a polymer, and only the liquid crystal undergoes phase separation. At this time, when the amount of liquid crystal is smaller than that of the resin component, independent particle-shaped liquid crystal droplets are formed. On the other hand, when the amount of liquid crystal is large, the resin matrix is particulate in the liquid crystal material. , Or exist in the form of a network and the liquid crystals are formed so as to form a continuous layer.

Unless the particle size of the water-drop liquid crystal or the pore size of the polymer network is uniform to some extent and the size is in the range of 0.1 μm to several μm, the incident light scattering performance is poor and the contrast cannot be improved. The particle size of the water-drop liquid crystal or the pore size of the polymer network is preferably in the range of 0.5 μm to 1.5 μm. For this reason, it is necessary to use a material that can be cured in a short time, such as an ultraviolet curable resin. Further, the orientation ratio of the liquid crystal material and the resin material is 95: 5 to 10:90, of which 50:50 to
A range of 90:10 is preferred.

The thickness of the liquid crystal layer 17 is 5 μm to 20 μm.
The range of 8 μm to 15 μm is most suitable for the scattering characteristics and the range of applied voltage for driving.
The film thickness may be set so that a maximum transmittance of 90% can be obtained with an applied voltage of 6 to 8V.

As a method of forming the diffraction grating, a pattern of the convex portions 13 is formed on the borosilicate glass, alkali glass or soda glass substrate with a metal or a resist, and reactive ion etching, chemical etching or the like is performed. In particular, reactive ion etching can be favorably formed because the edge of the convex portion is sharply formed. Refractive index n _g of the glass substrate is selected ones of 1.50 to 1.54, the refractive index is substantially matched to the refractive index n _p or liquid crystal ordinary refractive index n _o of the polymer of the polymer-dispersed liquid crystal 17. Normal,
Most glass substrates used for active matrix liquid crystal panels have a refractive index of 1.52 or 1.53,
This refractive index matches well with n _{o of the} polymer dispersed liquid crystal. After forming the convex portion 13 of the diffraction grating, ITO is vapor-deposited to form the counter electrode 16, and the ITO on the convex portion 13 is removed as necessary. The prototyped diffraction grating has a rectangular shape with a pitch of 6 μm and the height of the convex portions 13 of about 3 μm.

Beads are scattered on the counter electrode substrate 11 on which the above-mentioned diffraction grating is formed, while a sealing resin (not shown) is applied on the array substrate 12. Then, the counter electrode substrate 11 and the array substrate 11 are aligned and bonded. The film thickness of the prototype LCD panel is about 12μ
It was m. Liquid crystal injection methods include a vacuum injection method and a pressure injection method. In the vacuum injection method, after the array substrate 12 and the counter electrode substrate 11 are evacuated, the liquid crystal injection port is immersed in the liquid crystal solution. Next, when the vacuum in the vacuum chamber is broken, the liquid crystal solution is injected between both substrates. On the other hand, in the pressure injection method, the liquid crystal solution is injected by pressure from an injection port of 0.8 to 1.2 mm formed in the peripheral portion of the counter electrode substrate 11. After that, the injection port is sealed and irradiated with ultraviolet rays to polymerize the resin component of the liquid crystal solution, and the liquid crystal and the polymer are phase-separated.

Unlike the TN liquid crystal panel, the polymer dispersed liquid crystal panel does not require an alignment film and rubbing treatment,
Even if the convex portion 13 is formed, the liquid crystal layer can be easily formed.

The operation of the liquid crystal panel of the present invention will be described below.
explain. First, a voltage is applied between the counter electrode 16 and the pixel electrode 15.
Is not applied (hereinafter referred to as OFF state)
When, the refractive index n of the liquid crystal 17_offIs the extraordinary refractive index of the liquid crystal
n_e, The ordinary refractive index n_oAnd when the ratio of polymer is small
Then, then n_off= (2n_o+ N_e) / 3. Times
Refractive index n of the convex portion of the folded grid_gIs almost n_g= N_o= N_pWill be
I am also n _e> N_oTherefore n_g≠ n_offWhen
Become. Therefore, the difference in refractive index between the convex portion 13 and the liquid crystal 17 layer
Incident light on the liquid crystal panel is diffracted. Times
The broken light is scattered by the water-drop-shaped liquid crystal in the 17th layer of liquid crystal.
It

When a voltage is applied between the counter electrode 16 and the pixel electrode 15 and liquid crystal having a positive dielectric constant is vertically aligned (hereinafter, referred to as ON state), the refractive index n _on of the liquid crystal 17 is n. _o That is, n _on = n _g . Therefore, the liquid crystal layer becomes transparent and there is no difference in the refractive index between the convex portion 13 and the liquid crystal 17 layer. Therefore, the incident light on the liquid crystal panel goes straight on. Although no voltage is applied to the ITO on the convex portion, the ratio of the ITO to the ITO is about 1/4 of the area of the counter electrode 16, and the dielectric constant of the liquid crystal 17 is higher than that of the convex portion. Since it is sufficiently large, a substantially uniform electric field is applied between the liquid crystals 17. The refractive index n _g of the convex portion 13 is n _off.
May be matched with. In that case, the incident light on the liquid crystal panel is diffracted in the on state and goes straight in the off state.

When a voltage is applied between the ON state and the OFF state, an intermediate light scattering state is obtained. As described above, since the diffraction grating can be generated or eliminated by the applied voltage, the contrast can be made extremely high.

The liquid crystal projection television of the present invention will be described below with reference to the drawings. FIG. 4 is a configuration diagram of the liquid crystal projection television of the present invention. However, components that are unnecessary for the description are omitted. In FIG. 4, reference numeral 41 denotes a converging optical system, which has a concave mirror and a light generating means 2 inside.
It has a 50W metal halide lamp. Further, the concave mirror is configured to reflect only visible light.
Reference numeral 42 is a UVIR cut mirror that transmits infrared rays and ultraviolet rays and reflects only visible light. However, UVIR
It goes without saying that the cut mirror 42 may be arranged inside the condensing optical system 41. Also, 43a is BDM, 4
3b is GDM and 43c is RDM. In addition, BDM4
It is needless to say that the arrangement of 3a to RDM 43c is not limited to the order described above, and the last RDM 43c may be replaced by a total reflection mirror.

44a, 44b and 44c are liquid crystal panels of the present invention. Among the liquid crystal panels, the liquid crystal panel 44c that modulates the R light has a larger droplet diameter of liquid crystal particles or a larger liquid crystal film thickness than other liquid crystal panels. This is because the longer the wavelength of light, the lower the scattering characteristics. The particle size of the water-drop liquid crystal can be controlled by controlling the intensity of ultraviolet light during polymerization or by changing the material used. The liquid crystal film thickness can be adjusted by changing the bead diameter. Further, the height and pitch of the diffraction grating may be changed for each liquid crystal panel for red (R), green (G), and blue (B). In that case, the height of the diffraction grating of the liquid crystal panel for R is the highest and the height of the diffraction grating for B is the lowest. 45a, 45b, 45c, 47
a, 47b, 47c are lenses, 46a, 46b and 4
6c is an aperture as a diaphragm. 4
5, 46 and 47 constitute a projection optical system. A set of 45, 46 and 47 is called a projection lens system unless there is a particular problem. It is also clear that the aperture is not necessary when the F value of the lens 45 or the like is large, and it is also clear that the projection lens system can be replaced by one lens.

The projection lens system plays a role of transmitting parallel light rays transmitted through each liquid crystal panel and blocking light scattered by each liquid crystal panel. As a result, high-contrast full-color display can be realized on the screen. The contrast is improved by reducing the aperture diameter D of the aperture. However, the image brightness on the screen is reduced. When the pitch of the diffraction grating is 6 μm, the first-order diffracted light is about 6 degrees. Therefore, if the projection lens system is configured so as not to collect light of 6 degrees or more as much as possible, the contrast becomes high.

The thickness of the liquid crystal layer of the liquid crystal panel of the present invention is 1
When it is from 0 to 15 μm, the optimal condensing angle of the lens is within 6 degrees, and at that time, the contrast is 100: 1 at the center of the screen.
When projected on a 40-inch screen with a rear system television, the screen gain was 200 [ft] or more, and a screen brightness equal to or higher than that of the CRT projection television could be obtained.

The operation of the liquid crystal projection television of the present invention will be described below. Since the R, G, and B light modulation systems have substantially the same operation, the B light modulation system will be described as an example. First, white light is emitted from the condensing optical system 41, and the B light component of the white light is BDM 43.
It is reflected by a. The B light is incident on the polymer dispersed liquid crystal panel 44a. The polymer dispersed liquid crystal panel (see FIG.
As shown in FIGS. 8 (a) and 8 (b)), the scattering and transmission state of the incident light is controlled by the signal applied to the pixel electrode to modulate the light.

The scattered light is blocked by the aperture 46a, and conversely, the light within a predetermined angle passes through the aperture 46a. The modulated light is enlarged and projected on a screen (not shown) by the projection lens 47a. As described above, the B light component of the image is displayed on the screen. Similarly, the polymer dispersed liquid crystal panel 44b modulates the G light component light, and the polymer dispersed liquid crystal panel 44c modulates the R light component light so that a color image is displayed on the screen.

The projection lens system in FIG. 4 is not limited to this. For example, as shown in (FIG. 6), the parallel light is blocked by the light shield 62 and the scattered light is projected on the screen. It goes without saying that a mold type optical system may be used. This also applies to the liquid crystal projection type television having the configuration shown in FIG.

Further, in (FIG. 4), light is emitted from the counter substrate 1.
Although the light is incident from the first side, the present invention is not limited to this, and it is obvious that the same effect can be obtained even when the light is incident from the array substrate 12. As described above, the liquid crystal panel and the liquid crystal projection television of the present invention do not depend on the incident direction of light.

Further, the embodiment of the liquid crystal projection type television of the present invention is described as a rear type liquid crystal projection type television, but the present invention is not limited to this, and a front type liquid crystal projection type for projecting an image on a reflection type screen. It goes without saying that you can use TV. Further, in the liquid crystal projection television of the present embodiment, the color separation is performed by the dichroic mirror, but the present invention is not limited to this. For example, an absorption type color filter may be used to perform the color separation.

In the liquid crystal projection television of this embodiment, one projection lens system is provided for each of the R, G, and B light modulation systems, but the invention is not limited to this, and, for example, a mirror or the like. It goes without saying that a configuration may be adopted in which the display images modulated by the liquid crystal panel are combined into one by using, and are made incident on one projection lens system and projected. Further, it is not limited to providing a liquid crystal panel that modulates each of R, G and B lights. For example, a television that projects a picture of the panel by attaching a mosaic color filter to one liquid crystal panel may be used.

Further, although the liquid crystal panel of the present invention has been described as a transmissive liquid crystal panel, it is not limited to this, and it may be formed as a reflective type. In that case, the pixel electrode may be a reflective electrode made of a metal material. The block diagram is shown in FIG.

Furthermore, the Schlieren optical system may be used without being limited to the optical system shown in (FIG. 4) and (FIG. 5). The block diagram is shown in (FIG. 7). As the light modulation element, the liquid crystal panel of the present invention described above is used in a reflective structure. The projection light emitted from the projection light source 73 is focused on the mirror 72 by the condenser lens 74. The condensed light is reflected by the mirror 72, and the schlieren lens 75
Then, it becomes parallel rays and enters the liquid crystal panel 76 of the present invention. The light incident on the pixel for which the diffraction grating is completely generated is diffracted, enlarged by the schlieren lens 75, and projected on the screen 71. The light incident on the pixel in which the diffraction grating has completely disappeared is reflected as it is, and is shielded by the mirror / Schlieren stop 72. In the intermediate state between the generation and disappearance of the diffraction grating, the light according to the diffraction state is projected on the screen 71. Although the light diffracted in the liquid crystal projection type television described above is projected on the screen by the schlieren lens 75, the invention is not limited to this, and the schlieren optical system in which the diffracted light is shielded by the schlieren stop is configured. It goes without saying that it is okay.

Embodiments of the viewfinder of the present invention will be described below with reference to the drawings. FIG. 8 is an external view of the viewfinder of the present invention. In FIG. 8, 81 is a body, 82 is an eyepiece rubber, and 83 is a metal fitting for a video camera. FIG. 9 shows a sectional structure of the first embodiment of the viewfinder of the present invention.
Is a light emitting element, 93 is a condenser lens, 94 is the liquid crystal panel of the present invention, 132 is an eyepiece ring, and 131 and 133 are magnifying lenses.

In this embodiment, as an example, the diagonal length of the display area of the liquid crystal panel 94 is 28 mm, and the condenser lens 93 is used.
Has an effective diameter of 30 mm and a focal length of 95 mm. The light emitting element 91 is arranged near the focal point of the condenser lens 93. The condenser lens 93 is a plano-convex lens and has a flat surface facing the light emitting element 91 side. An eyepiece ring 132 is attached to an end portion of the body 92, and magnifying lenses 131 and 133 are attached to the body 92 and the eyepiece ring 132, respectively. The eyepiece lens and the condenser lens can be replaced with a Fresnel lens or the like. The above also applies to the following embodiments.

The light emitted from the light emitting element 91 in a wide solid angle is converted into light having a narrow directivity by the condenser lens 93, and is converted into light having a narrow directivity.
Incident from the side. The liquid crystal panel 94 changes the amount of light transmission or the degree of scattering of light according to a video signal to form an image. The observer brings the eye into close contact with the eyepiece ring 132 to see the display image on the liquid crystal panel 94. That is, the position of the observer's pupil is almost fixed. Condenser lens 93
When all the pixels of the liquid crystal panel 94 let light go straight,
Light emitted from the light emitting element 91 and incident on the effective area of the condenser lens 93 passes through the magnifying lenses 133 and 131, and then all enters the observer's pupil. The combination of the two lenses 133 and 131 functions as a magnifying lens, so that an observer can magnify and see a small display image on the liquid crystal panel 94.

As the light emitting element, a cathode ray tube, an arc tube using a light emitting principle such as a fluorescent lamp, a fluorescent display tube, a xenon lamp,
Halogen lamp, tungsten lamp, metal halide lamp, LED, EL (Electro Lumine)
element that emits light by the action of electrons such as
PDP (Plasma Display Panel)
Illustrative examples include those that self-luminece such as those that emit light upon discharge. Above all, arc tubes and LEDs are most suitable in terms of low power consumption, small size, and color temperature. The light emitting device 91 of the viewfinder of the present invention will be described below.

The external appearance of the arc tube is a miniature bulb shape. 101 is a case made of glass and has a diameter of 5 mm.
~ 30 mm. 102 is a filament, 4V
A voltage of about 10 V is applied to heat the filament 102. 103 is an anode, and the applied voltage is about 0 to 25V. According to the anode voltage, the filament 10
The electrons emitted by the heating of 2 are accelerated. Case 1
01 contains mercury molecules (not shown), and the accelerated electrons emit ultraviolet rays by colliding with the mercury molecules. This ultraviolet ray excites the phosphor 105 to generate visible light. Reference numeral 104 is a reflective film made of metal or the like.
The reflection film 104 has a function of reflecting and improving the forward divergence rate of light.

A structure in which an LED is used as the light emitting element 91 is shown in FIG. 111 is a resin lens, 112
Is a light emitter and 113 is a terminal. The light-emitting body is composed of red, green, and blue light-emitting chips, and has four terminals, one terminal for each light-emitting chip of each color and a common terminal. The three light emitting chips are molded with transparent resin.

In order to improve the gradation of the display image on the liquid crystal panel 94, it is desirable that the transmittances of the red, green and blue pixels be substantially equal. Then, the emission color of the LED needs to emit white light with a predetermined chromaticity. LED
By controlling the voltage or current applied to each of the red, green, and blue light emitting chips, the emission color of the light emitting pair can be adjusted, and the chromaticity of the image displayed on the liquid crystal panel 94 can be adjusted. This chromaticity adjustment is extremely easy as compared with the case where a fluorescent light backlight is used.

The surface of the LED molding resin can be used as a lens. In particular, as shown in (FIG. 12), if the surface of the mold resin is spherical and the light emitted from the light emitter satisfies the aplanatic condition, the display shows the radius of curvature of the lens surface of the mold resin as r , And the refractive index is n, from the vertex 126 of the lens surface to S = (1 + 1 /
It is preferable to dispose the light-emitting body 123 at a position separated by n) · r. At this time, the image of the light-emitting body 123 on the lens surface can be formed at a position 124 separated by S ′ = (1 + n) · r from the vertex 126 of the lens surface. Since the size of the light-emitting body 123 is sufficiently smaller than the diameter of the condenser lens, it can be regarded as a point.

A mosaic color filter (not shown) is attached to the liquid crystal panel 94. Each color filter transmits any color of red, green, and blue. The film thickness of each color may be controlled by the composition of the color filter. The film thickness of the color filter is adjusted and formed when the color filter is manufactured. That is, the thickness of the color filter is red,
Change with green and blue. The film thickness of the liquid crystal on each pixel can be adjusted according to the color of each color filter by the film thickness of the color filter. The liquid crystal panel 94 has poor scattering characteristics for long-wavelength light (red). Therefore, if the liquid crystal layer thickness of the red pixel is made thicker than that of the other blue and green pixels, the scattering performance can be improved and the red, green and blue gradations can be made uniform.

The condenser lens 93 has a flat surface, that is, a surface having a large radius of curvature, facing the light emitter side. This makes it easy to satisfy the sine condition and improves the brightness uniformity of the display image on the liquid crystal panel 94. This is because By adjusting the degree of insertion of the eyepiece ring 132 into the body 92, the focus can be adjusted according to the visual acuity of the user. It should be noted that the two positive lenses 131 and 133 may be configured by one lens. Further, even if the viewpoint position of the user is slightly shifted, the display image can be viewed well. Since the position of the observer's eyes with respect to the eyepiece ring 132 is fixed, it is necessary to arrange the light emitting element 11 at a predetermined position so that the observer can see a good image. Therefore, although not shown, the light emitting element 91 is provided with a position adjusting mechanism so that the light emitting element 91 can be moved back and forth or left and right to some extent.
The two positive lenses 131 and 13 shown in (FIG. 13) are
It is also possible to remove 3 and use the configuration shown in FIG.

A diaphragm 141 may be arranged in the vicinity of the light emitting element 91 to have a structure as shown in FIG. This makes it possible to reduce the size of the light emitting portion of the light emitting element 91, reduce unnecessary light, and at the same time improve the contrast of the display image on the liquid crystal panel 94. The diaphragm 141 may be a variable diaphragm used in a camera, and the hole diameter of the diaphragm 141 may be changed by rotating a lever (not shown) taken out of the body 81. However, it is necessary to arrange so that the center of the diaphragm 141 passes through the central axis of the condenser lens 13.

With the above configuration, the light emitting element 91
Since the light emitted from a small illuminant with a wide solid angle is efficiently condensed by the condenser lens 93, the power consumption of the light source can be significantly reduced as compared with the case where a fluorescent light backlight is used. it can.

[0065]

As described above, since the liquid crystal panel of the present invention uses the polymer-dispersed liquid crystal, it is possible to obtain a high-brightness screen which is more than twice as bright as the liquid crystal panel using the TN liquid crystal. Further, since the diffraction grating is formed in the liquid crystal panel, the amount of straight transmission of light in the off state of the liquid crystal can be significantly reduced due to the scattering effect and the diffraction effect in the liquid crystal layer. On the contrary, when the liquid crystal is on, the diffraction grating disappears, so that the incident light goes straight on. Therefore, a contrast of 100 or more can be achieved, and high-quality image display with very good gradation display characteristics can be realized. Further, since the diffraction grating is formed by processing the counter electrode substrate, it has high mechanical strength and is easy to form.

In the liquid crystal projection television of the present invention, since the liquid crystal panel of the present invention is used, it is possible to realize high brightness image quality and high contrast display. Further, in the liquid crystal projection television of the present invention, the average particle diameter or the pore diameter of the water droplet liquid crystal is changed or the height of the diffraction grating is changed in accordance with the R, G, and B wavelengths. As a result, the contrast at each wavelength is significantly improved, and high quality image display can be realized.

In the viewfinder of the present invention, the light emitted from the small light-emitting body of the light-emitting element in a wide solid angle is converted into parallel light having a narrow directivity by the condenser lens, and the viewfinder of the liquid crystal panel of the present invention is used. Since the image is modulated and displayed, power consumption is low, unevenness in luminance is small, and the drive circuit of the light emitting element has a simple structure, so that a compact and lightweight viewfinder can be provided.

Further, since the light emitting element for the viewfinder has the red, green and blue light emitting portions inside, it is possible to provide a viewfinder for color display, and when an LED is used as the light emitting element, the red light is used. The white balance of the emission color can be easily adjusted by the applied voltage to each of the green, green, and blue light emitters.

Further, since the viewfinder of the present invention consumes less power, the continuous use time can be remarkably lengthened by mounting the viewfinder on the video camera.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a liquid crystal panel according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a liquid crystal panel according to an embodiment of the present invention.

FIG. 3 is a plan view of a counter electrode substrate of the liquid crystal panel of the present invention.

FIG. 4 is a configuration diagram of a liquid crystal projection television according to an embodiment of the present invention.

FIG. 5 is a configuration diagram of a liquid crystal projection television according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram of one component of the liquid crystal projection television of the present invention.

FIG. 7 is a configuration diagram of a liquid crystal projection television according to an embodiment of the present invention.

FIG. 8 is an external view of the viewfinder of the present invention.

FIG. 9 is a sectional view of a viewfinder according to an embodiment of the present invention.

FIG. 10 is an explanatory diagram of a light emitting element of a viewfinder.

FIG. 11 is an explanatory diagram of a light emitting element of a viewfinder.

FIG. 12 is an explanatory diagram of a light emitting element of a viewfinder.

FIG. 13 is a cross-sectional view of the viewfinder of the present invention.

FIG. 14 is a cross-sectional view of the viewfinder of the present invention.

FIG. 15 is an equivalent circuit diagram of a liquid crystal panel.

FIG. 16 is a cross-sectional view of a conventional liquid crystal panel.

FIG. 17 is a configuration diagram of a conventional liquid crystal projection television.

FIG. 18 is an explanatory diagram of the operation of the polymer dispersed liquid crystal panel.

[Explanation of symbols]

11, 161, 181 Counter electrode substrate 12, 162, 181 Array substrate 13 Convex portion 15, 182 Pixel electrode 16, 183 Counter electrode 17 Polymer dispersed liquid crystal 44a, 44b, 44c Polymer dispersed liquid crystal panel 46a, 46b, 46c Averter 51 Screen 73 Projection light source 74 Condenser lens 75 Schlieren lens 91 Light emitting element 93 Condensing lens 94 Liquid crystal panel 104 Reflective film 105 Fluorescent substance 111 Resin lens 112 Light emitting element 131, 133 Magnifying lens 132 Eyepiece 141 Aperture 163 TN liquid crystal 167 Black matrix 168a, 168b Alignment film 174a, 174b, 174c, 176a, 176b,
176c Polarizing plate 175a, 175b, 175c TN liquid crystal panel 184 Water droplet liquid crystal 185 Polymer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location G02F 1/1335 7724-2K

Claims (10)

[Claims] 1. A polymer dispersed liquid crystal is sandwiched between a pixel electrode substrate having a pixel electrode and a counter electrode substrate having an electrode facing the pixel electrode and facing the polymer dispersed liquid crystal on the counter electrode substrate. A liquid crystal panel having a two-dimensional diffraction grating formed on its surface. 2. The liquid crystal panel according to claim 1, wherein a counter electrode is formed in the concave portion of the diffraction grating. 3. The liquid crystal panel according to claim 1, wherein the convex portion of the diffraction grating is formed of a counter electrode substrate material. 4. The refractive index of the convex portion of the diffraction grating is substantially equal to the refractive index of the resin material of the polymer dispersed liquid crystal or the refractive index of the polymer dispersed liquid crystal in the scattered state. The described liquid crystal panel. 5. A liquid crystal panel according to claim 1, a light generating means, a first optical element part for guiding the light generated by the light generating means to the liquid crystal panel, and light modulated by the liquid crystal panel. A liquid crystal display device comprising a second optical element component for projecting. 6. The light generated by the light generating means is split by a color filter into light of three predetermined wavelengths, blue light, green light and red light, and the liquid crystal panel has a wavelength of the three predetermined wavelengths. The liquid crystal display device according to claim 5, wherein the liquid crystal display device is arranged for at least one of the lights. 7. The liquid crystal display device according to claim 6, wherein the color filter is a dichroic mirror. 8. An optical element for forming an optical image of a liquid crystal panel that modulates blue light, an optical image of a liquid crystal panel that modulates green light, and an optical image of a liquid crystal panel that modulates red light.
7. The liquid crystal display device according to claim 6, wherein the images are projected on the same position on the screen. 9. The liquid crystal panel according to claim 1, comprising a light emitting element, a condensing means for converting light emitted from the light emitting element into substantially parallel light, and light emitted from the condensing means. Liquid crystal display device. 10. A light emitting element, a condensing means for converting light emitted from the light emitting element into substantially parallel light, and a diaphragm means arranged in the vicinity of the light emitting element for controlling light emitted from the light emitting element. 2. A liquid crystal display device comprising: the liquid crystal panel according to claim 1, which modulates the light emitted from the light condensing unit.