JPH07270780A - Projection type display device - Google Patents

Abstract

PURPOSE:To provide a projection type display device which is small in size, is easy to be installed and is capable of displaying stereoscopic images by converting illuminating light into linearly polarized light and projecting the output light of light valve for modulating a polarization state by alternately changing over the polarization direction of the output light for the right and left eyes at every line of display images. CONSTITUTION:The illuminating luminous flux of a lamp 11 is separated into three primary color light rays of red, green and blue by dichroic mirrors 2R, 2G. These rays illuminate liquid crystal panels 6R, 6G, 6B through reflection at reflection mirror 3 to 5. These liquid crystal panels 6R, 6G, 6B have matrix electrodes and output the image light rays which are changed in the transmittance distribution within the plane and are linearly polarized with the three primary color images. Polarization switching element 21R, 21G, 21B control the polarization directions of the light rays transmitting through the liquid crystal panels by each of the respective lines and allow the transmitted light rays of the respective lines to be transmitted by alternately switching over the polarization directions for the right and left eyes. The transmitted light rays of these elements are synthesized by a dichroic prism 7 which reflects the red and blue light rays and allows the green light rays to be transmitted and are projected by a projecting lens 8 onto a screen 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display device capable of displaying a stereoscopic image using polarized light.

[0002]

2. Description of the Related Art FIG. 10 is an explanatory view of a projection type display device capable of displaying a stereoscopic image according to a first conventional example. In the figure, 60R and 60L are projectors for the right eye and projectors for the left eye, 61 and 62 are polarizing plates, 10 is a screen, and 23 is polarizing glasses.

Next, the operation will be described. Each of the projectors 60R and 60L has a built-in image display device such as a CRT or a liquid crystal panel. For the right eye output from a signal source (not shown) to these image display devices,
The parallax image for the left eye is displayed, and the projectors 60R, 60
The parallax image is displayed on the screen 1 by the projection lens at the tip of L.
Projected on top of 0.

Polarizing plates 61 and 62 whose polarization axes are orthogonal to each other are arranged at the projection lens emission ends of the projectors 60R and 60L, and the projected images for the right eye and the left eye are projected as linearly polarized light orthogonal to each other. The viewing of the image is performed by wearing the polarized glasses 23. That is, the right eye projector 60 for the right eye and the right eye projector 60 for the left eye of the polarizing glasses respectively.
Polarizing plates 26R and 26L having polarization axes orthogonal to each other are provided so as to selectively transmit the linearly polarized light projected by the R and left-eye projectors 60L, and the magnified and projected parallax image is viewed by the right and left eyes, respectively. Can realize stereoscopic vision.

FIG. 11a shows, for example, "Imai et al .: Proceedings of IEICE Spring National Convention (1989), C-84".
FIG. 6 is a configuration diagram of a projection display device that is capable of displaying a stereoscopic image according to a second conventional example, described in FIG. In the figure, 1 is a light source, 50, 51 and 52 are mirrors, 53 and 55 are polarization beam splitters, 54L and 54R are color liquid crystal panels,
56 is a λ / 4 plate, 8 is a projection lens, and 9 is projection light.

Next, the operation will be described. A light beam emitted from the light source 1 is split into two linearly polarized light beams having polarization components (p-polarized light and s-polarized light) orthogonal to each other by a polarization beam splitter 53, and two parallax images for the right eye and the left eye are displayed respectively.
The liquid crystal panels 54R and 54L are illuminated. The s-polarized and p-polarized transmitted lights emitted from the liquid crystal panels 54R and 54L are combined by the polarization beam splitter 55, and the p-polarized and s-polarized linearly polarized lights are rotated clockwise and counterclockwise by the λ / 4 plate 56, respectively. The liquid crystal panel 54R is converted into light and is projected by the projection lens 8.
The parallax image of 54L is converted into the projection light 9 and enlarged and projected on a screen (not shown). As shown in FIG. 11 (b), the observer 24 uses a λ / 4 plate 25 that returns circularly polarized light to linearly polarized light.
Polarizing plate 26 having polarization axes orthogonal to each other in R and 25L
Stereoscopic vision can be realized by wearing the circularly polarized glasses 23 to which R and 26L are attached and selectively observing the images for the right eye and the left eye with the corresponding eyes.

[0007]

In the projection display device of the first conventional example shown in FIG. 10, two projectors 60L and 60R are necessary for projecting a parallax image, and a stereoscopic image can be observed without fatigue. In order to do so, it is necessary to make an adjustment so that the parallax images are correctly superimposed on the screen 10. Due to these factors, there is a problem that the entire apparatus is expensive and large-sized, and it takes time to install and adjust the apparatus.

In the second conventional apparatus shown in FIG. 11, a single projector can project a parallax image. Therefore, although the above-mentioned problems of the first conventional example are solved, a color stereoscopic image is projected. In order to do so, it is necessary to use, as the liquid crystal panels 54R and 54L, a color panel in which pixels of three primary colors of red, green, and blue are arrayed, and the number of pixels for each primary color cannot be sufficient in order to increase the definition of the projected image. There was a problem. Moreover, if each primary color light is obtained by the color filter arranged on each pixel of the liquid crystal, in principle, the color filter is 2/3.
The above luminous flux is lost, which has been a problem in achieving high brightness.

The present invention has been made in order to solve the above problems, and a first object thereof is to provide a projection type display device which is compact and capable of displaying a stereoscopic image which is easy to install. is there.

A second object of the present invention is to provide a projection type display device which can secure a sufficient number of pixels and can display a stereoscopic image suitable for high brightness.

A third object of the present invention is to provide a projection type display device which can realize a three-dimensional image display with high reliability and less flicker.

A fourth object is to provide a projection type display device in which crosstalk between left and right parallax images is small.

A fifth object is to provide a small-sized projection display device which is easy to assemble.

[0014]

In the projection display device according to the present invention, a light valve for converting illumination light emitted from a light source into linearly polarized light and modulating the in-plane polarization state according to an image signal to be displayed. And a polarization switching element that alternately switches the polarization direction of the output light of the light valve for each row of the display image for the right eye and the left eye, and a projection lens that magnifies and projects the light flux output from the polarization switching element. is there.

Further, a plurality of light valves for displaying images and polarization switching means on each emission side of the light valves are provided, and the output light of each polarization switching means is combined and projected.

Further, a plurality of light valves for displaying an image, and polarization switching means on the emission side of each light valve,
It is provided with a λ / 4 plate that converts the output light of each polarization switching unit into a right-handed circularly polarized light and a left-handed circularly polarized light according to the polarization switching state, and compositely projects the output light of each polarization switching unit. .

Further, the light valve for image display has pixel electrodes which are periodically arranged at least in the vertical direction of the display screen, and the polarization switching means has row electrodes which are periodically arranged in the vertical direction in correspondence with the pixel structure. It is provided, and the polarization state of the output light of each display row of the light valve can be independently switched according to the signal applied to the row electrode.

The image display light valve is composed of a cell in which a TN mode liquid crystal is sealed and a first liquid crystal panel which is composed of a polarizing plate disposed on the illumination light incident side or both of the illumination light incident / exiting side, and the polarization switching is performed. The means comprises a second liquid crystal panel having a structure in which a ferroelectric liquid crystal is sandwiched between two transparent substrates, and the ferroelectric liquid crystal has an alignment direction of liquid crystal molecules in the plane of the transparent substrate according to the polarity of an applied voltage. State 1 and State 2
In the state 1, the polarization direction of the emitted light of the first liquid crystal panel is transmitted without rotating, and in the state 2, the polarization direction of the emitted light of the first liquid crystal panel is rotated by 90 °. It is made transparent.

Further, the light valve for displaying an image is composed of a cell in which a TN mode liquid crystal is enclosed and a first liquid crystal panel which is composed of a polarizing plate disposed on the illumination light incident side or both the illumination light incident / exiting side. The switching means is composed of a second liquid crystal panel having a structure in which TN mode liquid crystal is sandwiched between two transparent substrates, and the TN mode liquid crystal of the second liquid crystal panel has two states of state 1 and state 2 depending on an applied voltage. In the state 1, the polarization direction of the emitted light of the first liquid crystal panel is transmitted without rotating, and in the state 2, the polarization direction of the emitted light of the first liquid crystal panel is rotated by 90 °. It is transparent.

The image signal to be projected and displayed is output from a pair of image signal sources for the left eye and the right eye, and the row output of the image signal source for the left eye and the row output of the image signal source for the right eye are set to (L
1, L2, L3, L4, ..., Ln-1, Ln), and (R1, R2, R3, R4 ,.
.., Rn-1, Rn), in the odd field, (L
1, R2, L3, R4, ... Ln-1, Rn) is displayed, and in the even field, (R1, L2, R3, L4, ... Rn-1, Ln) is displayed. , A scanning circuit for switching the state of the polarization switching means according to the eye corresponding to each row in synchronization with the display of each row of the odd field and the even field.

The projection lens is a telecentric lens system in which the off-axis chief ray on the light valve side is parallel to the optical axis of the projection lens, and the light valve and the polarization switching means both have an electrode structure which is periodic in the vertical direction. The light bulb and the polarization switching means have the same vertical electrode pitch.

The projection lens is a non-telecentric lens system, the light valve has a periodic electrode structure with a vertical pitch Pl, and the polarization switching means has a vertical pitch Pe. If the optical distance from the polarization switching means to the entrance pupil of the projection lens means is L2 and the optical distance from the light valve to the entrance pupil of the projection lens means is L1, then Pl, P1 Satisfies the relation of the following equation. Pl / Pe
= L1 / L2

Further, the light valve and the polarization switching means are integrally formed so that no space is provided between them.

[0024]

In the projection type display device configured as described above, by switching the polarized light output from the light valve for each row, it is possible to display separate parallax images for the right eye and the left eye. It is possible to realize a projection type display device that can be installed easily and can display a stereoscopic image.

Further, since the output light from a plurality of light valves is combined and projected, a high-definition and high-luminance stereoscopic image can be displayed.

Further, the combined light of a plurality of light valves is expressed by λ
Since the / 4 plate converts the light into circularly polarized light that rotates in the opposite directions for the right eye and the left eye and can project the light, crosstalk between the left and right parallax images can be reduced even if the observer tilts the head to the left or right.

Further, by applying a scanning signal to the row electrodes having a periodic structure, the state of the polarization switching element is switched so as to alternately output the images for the left eye and the right eye for each row, thereby providing a highly reliable device. realizable.

Further, since the polarization of the display image of the TN mode liquid crystal can be controlled by the polarization switching element made of the ferroelectric liquid crystal which operates at high speed, a stereoscopic image display with high contrast can be realized.

Further, since the polarization of the display image of the TN mode liquid crystal can be controlled by the polarization switching element of the TN mode liquid crystal, a relatively inexpensive projection display device can be obtained.

Further, since the image for the right eye and the image for the left eye can be interlaced by the action of the light valve drive circuit, the polarization switching element and the scanning circuit, stereoscopic display with less flicker is possible.

Further, the combination of the telecentric projection lens, the light valve having the same vertical electrode period, and the polarization switching element can eliminate crosstalk in stereoscopic display.

Further, the ratio of the distance from the entrance pupil position of the non-telecentric lens to the light valve and the polarization switching element is made equal to the ratio of the vertical electrode cycle of the light valve and the vertical electrode cycle of the polarization switching element. By that,
Crosstalk in stereoscopic display can be eliminated.

Further, since the light valve and the polarization switching element are integrally formed, the projection display device can be easily assembled, and the projection display device that is compact and has a small crosstalk between the left and right images can be obtained. To be

[0034]

【Example】

<First Embodiment> FIG. 1 is a block diagram showing the optical system of a projection display apparatus according to the first embodiment of the present invention. In the figure, 1
Is a light source and includes a lamp 11 that emits white light, and a reflecting mirror 12. 2R is a dichroic mirror that reflects red light and transmits green and blue light. 2G is a dichroic mirror that reflects green light and transmits blue light.
Reference numerals 4 and 5 are reflection mirrors, 6R, 6G and 6B are liquid crystal panels (light valves) for displaying an image in the plane, 21R and 21R.
G and 21B are polarization switching elements, 8 is a projection lens, 10 is a screen, 23 is polarizing glasses, and polarizing plates 26L and 26R having polarization axes orthogonal to each other are provided for the left and right eyes.

Next, the operation will be described. The light source 1 is, for example, a metal halide lamp, a xenon lamp, a halogen lamp, or the like, which is a reflecting mirror for reflecting the light flux of a lamp 11 that emits white light.
At step 2, it is converted into a parallel illumination light flux. The illumination luminous flux is decomposed into three primary color lights of red, green and blue by dichroic mirrors 2R and 2G made of a dielectric multilayer film, reflected by reflection mirrors 3, 4 and 5 to illuminate liquid crystal panels 6R, 6G and 6B.

As will be described later, the liquid crystal panels 6R, 6G, and 6B have a structure in which a TN (Twisted Nematic) mode liquid crystal cell is sandwiched between two polarizing plates, and the liquid crystal cell has matrix electrodes in the vertical and horizontal directions on its inner surface. . The liquid crystal panel changes the in-plane transmittance distribution of the three primary color images corresponding to red, blue, and green by an output signal of a drive circuit (not shown), and outputs linearly polarized image light. Polarization switching elements 21R, 21
G and 21B can control the polarization direction of the transmitted light of the liquid crystal panel for each row, as will be described later.
The transmitted light of each row of R, 6G, 6B is for the right eye. The polarization direction for the left eye is alternately switched and transmitted.

The transmitted light of the polarization switching element is combined by a dichroic prism 7 of a four-division structure that reflects red and blue light and transmits green light, and is enlarged and projected as projection light 9 on a screen 10 by a projection lens 8. . The viewer 24 views the projected image on the screen 10 through the polarized glasses 23.

When the screen is a transmissive type, the observer views the screen on the side opposite to the projection lens 8 as shown in the figure, and when the screen is a reflective type, the observer views the screen on the projection lens 8 side. To do. Polarizing glasses 23 are provided with polarizing plates 26L and 26R having polarization axes orthogonal to each other in portions corresponding to the left and right eyes, and a stereoscopic effect can be obtained by viewing the corresponding parallax images for the left and right eyes.

FIG. 2 is a diagram showing the arrangement of the liquid crystal panel 6 and the polarization switching element 21 which are the main parts of the configuration of FIG. The liquid crystal panel 6 is composed of an incident side polarization plate 6P, an emission side polarization plate 6A, and a liquid crystal cell 6L sandwiched therebetween. Liquid crystal cell 6
As is well known, L is a TN liquid crystal injected between two transparent substrates. On the inner surface of the transparent substrate, a matrix electrode 6M having a periodic structure in the vertical / horizontal directions, an alignment layer for operating the liquid crystal in the TN mode, and the like are formed. Further, in order to display an image with good contrast, a thin film transistor (T
FT) is formed. Also, the polarization axes of the polarizing plates 6P and 6A are typically orthogonal as shown by the arrows,
Or they are in parallel.

The polarization switching element 21 includes a transparent substrate 21F,
A liquid crystal material is injected between 21R, transparent substrate 21F,
A transparent electrode and an alignment layer are formed on the inner surface of 21R.
At least one of the transparent electrodes is patterned so as to have a periodic structure in the Y direction (upward to downward direction), and is formed in strips by the number corresponding to the row of the matrix electrodes of the liquid crystal panel 6 (the set of pixels in the X direction). Can be driven separately. The polarization switching element 21 is in a state of transmitting the transmitted light of the liquid crystal panel 6 without changing the polarization direction thereof according to the voltage applied to the strip electrodes (state 1) and a state of rotating the polarization direction by 90 degrees (state 2). Can be set for each line.

Images for the left eye / right eye are alternately displayed for each row on the matrix electrodes 6M in accordance with a signal applied from a liquid crystal panel drive circuit 30 described later. Further, the strip electrodes 21C are alternately switched to two states for the right eye / the left eye in accordance with a signal from the scanning circuit in synchronization with the writing of the image to the matrix electrodes row by row. In this way
Incident light Li has a linear polarization direction of 9 for the left eye / right eye for each row.
It is converted into image light Lo having a difference of 0 ° and enlarged and projected by the projection lens. In FIG. 1, since three sets of the liquid crystal panel 6 and the polarization switching element 21 are combined and projected, the display image has the number of pixels of each liquid crystal panel for each primary color, and the color liquid crystal is projected (FIG. 11). Higher definition is possible. Furthermore, dichroic mirror 2 for color separation
If the joint surface of the dichroic prism 7 for R, 2G, and color combination is made of a known dielectric multilayer film, the spectrum of the illumination light emitted from the lamp can be separated and combined with low loss. Therefore, in principle, a high-luminance color projection image can be obtained as compared with the color liquid crystal panel projection system (FIG. 11) that loses 2/3 of the illumination light spectrum.

Next, as an example of the polarization switching element, an electro-optical λ / 2 plate (EO-HW: Electro Optical Hal) using a ferroelectric liquid crystal (FLC: Ferroelectric Liquid Crystal).
f Wave Plate) will be described with reference to FIG. FIG. 5 is an operation explanatory diagram of the deflection switching element used in the present invention.
In the figure, the FLC cell 21 has a structure in which FLC is injected between two transparent substrates having a transparent electrode and an alignment layer on the inner surface. FLC is a uniaxial birefringent material whose optical axis is parallel to the average alignment direction of liquid crystal molecules. By properly setting the FLC layer thickness, the amount of phase shift can be set so that it functions as a λ / 2 plate. Further, the orientation direction of the FLC molecules is switched to two directions parallel to the FLC layer which make 45 ° with each other depending on the direction of the applied electric field. Therefore, the orientation direction of the FLC can be switched by applying a positive / negative voltage to the transparent electrode.

As shown in FIG. 5A, when the direction of the optical axis (Optical Axis) when the voltage -V is applied is aligned with the polarization direction of the incident light, the polarization direction of the transmitted light does not change. on the other hand,
When a voltage + V is applied as shown in FIG. 5B, the optical axis of the FLC rotates by 45 ° in the panel plane, so that the polarization of the transmitted light rotates by 90 ° as compared with FIG. 5A. In addition, in Figure 5, EO-H
In W, the transparent electrode is not divided, but even if the transparent electrode is divided into rows as shown by 21C in FIG. 2, the operation principle of the elements in each row is the same as in FIG. Also, since the response speed of FLC is typically as short as 100 μs or less, a stereoscopic image can be displayed with good contrast for the left and right eyes even when the polarization is switched for each row as shown in FIG.

Regarding the principle of polarization switching using the FLC as described above, for example, (■ Background on Ferroelectri
c Liquid Crystals (FLCs) ■, DISPLAYTECH Inc.
(1991)).

In addition to FLC, there is known a liquid crystal retarder in which the amount of phase shift due to birefringence of nematic liquid crystal is controlled by an applied voltage. Such an element may be used as the EO-HW in place of the FLC described above. In this case, since the amount of phase shift changes continuously with respect to the AC applied voltage, the amount of phase shift is 0λ.
It suffices to switch the state between the voltage of 4 and the voltage of λ / 4. For more information on liquid crystal retarders with nematic liquid crystals, see, for example, ("Polarization Optics Catalog & Handbook ■, p
p.8-9, published by Meadowlark Optics, 1990). In addition to this, it goes without saying that any element whose amount of phase shift can be electrically adjusted can be used for polarization switching in the apparatus of the present invention by performing row division driving. In this way, the device of the present invention does not rely on a mechanical mechanism for switching the polarization, so that the projection display device can be made highly reliable.

Next, the details of the drive circuit will be described with reference to the drawings. FIG. 3 is a configuration diagram of a drive circuit and a scanning circuit of the liquid crystal panel 6 and the polarization switching element 21 according to the present invention. In the figure, 31L and 31R are signal sources for the left eye and the right eye, respectively.
32 is a video memory including a left-eye memory 32L and a right-eye memory 32R, 33 is a composite drive signal generation circuit, and the video memory 32 and the composite drive signal generation circuit 33 constitute a liquid crystal panel drive circuit 30. The outputs of the image signal sources 31L and 31R corresponding to the left and right eyes are held in the memories 32L and 32R for one screen.

In the figure, L1, L2, L3 ... Ln are memories 32L
Image data for n rows for the left eye held by In addition, R1, R2, R3, ... Rn are image data for the right eye for n rows held in the memory 32R. The data held in the video memory 32 is converted into the data for the left eye and the data for the right eye alternately for each row in the composite drive signal generation circuit 33, and the rows LC1, LC2, LC3, ... Of the matrix electrodes of the liquid crystal panel 6 are converted.
..., output to LCn in order.

FIG. 4A shows changes in the display state of the liquid crystal panel 6. In the figure, Tf is the field period, and in the first field, the first field as (L1, R2, L3, R4, ..., Ln-1, Rn)
The image is displayed in order from the row to the nth row, and in the second field, the image is sequentially displayed from the first row to the nth row as (R1, L2, R3, L4, ..., Rn-1, Ln). indicate. Similarly, the next screen data is written in the third and fourth fields, and this is repeated thereafter. According to this data display method, the image for the left eye and the image for the right eye are interlaced, and the display of one screen is completed with a total of two fields. Therefore, for example, a method of alternately displaying the images for the left eye and the right eye for each field Compared with this, image flicker can be reduced.

In FIG. 3, the polarization switching element 21 outputs each row (C1, C2, C3, ..., Cn-1, Cn) according to the output of the scanning circuit 40.
The state of n) is switched. FIG. 4B shows the change over time in the state of the polarization switching element 21. In the figure, Tf is a field period and Th is a horizontal scanning period. In the figure, the symbols (+, −) indicate two states of voltage applied to each row electrode in order to set the polarization switching state for the left eye and the right eye, respectively. It should be noted that the symbols (+, −) are not necessarily the symbols of the voltage applied to the liquid crystal, but are merely for the purpose of distinguishing and showing the two states. In the first field, (+,-, +,-, ...
., +,-), And the polarization switching state corresponding to the left-eye and right-eye data of the first field in FIG. 4a is entered. In the second field, the first field is synchronized with the horizontal scanning cycle.
The state transits to (-, +,-, + ...,-, +) in order from the line, and
The polarization switching state corresponding to the right-eye and left-eye data of the second field of a is set. After that, in the odd and even fields,
Signals similar to those in the first and second fields are repeatedly applied to the polarization switching element 21.

In FIG. 3, the signal sources 31L, 31
The operations of R, the video memory 32, the composite drive signal generation circuit 33, and the scanning circuit 40 are performed in synchronization with the common horizontal synchronization signal Hsync and field synchronization signal Fsync.

By the way, when the principal rays emitted from the corresponding rows of the liquid crystal panel and the polarization switching element in the projected light are deviated, crosstalk occurs in the projected images of the left and right eyes. Therefore, a preferable setting of the row pitch of the liquid crystal panel 6 and the row pitch of the polarization switching element 21 will be described with reference to FIG. Figure 6a
The projection lens 8 shown in is a known telecentric projection lens in which the entrance pupil on the liquid crystal panel side is located at infinity, and the principal ray on the liquid crystal panel 6 side is parallel to the optical axis of the projection lens 8 as indicated by the arrow. Has become. In the figure, Pl and Pe are the row pitches of the liquid crystal panel 6 and the polarization switching element 21, respectively. In this case, Pl = Pe
It can be seen that the relationship of (1) can eliminate the deviation of the row positions of the liquid crystal panel and the polarization switching element in the projected image.

The projection lens 8 shown in FIG. 6b is a known non-telecentric projection lens in which the entrance pupil 8I on the liquid crystal panel 6 side is located at a finite distance, and the chief ray on the liquid crystal panel side is the entrance pupil 8I as shown in the figure. Incident on the center of. Pl / Pe = L1 / L2 (2) To eliminate the misalignment of the line positions of the liquid crystal panel and the polarization switching element in the projected image
And it is sufficient. Where Pl is the row pitch of the liquid crystal panel, P
e is the row pitch of the polarization switching element, L1 is the optical distance from the image display surface of the liquid crystal panel to the entrance pupil 8I, and L2 is the optical distance from the polarization switching element to the entrance pupil 8I. Once the specifications of the projection lens, the liquid crystal panel, and the arrangement of the polarization switching element are determined, the row pitch may be determined so that the ratio of Pl to Pe satisfies the expression (2).

<Second Embodiment> In the configuration shown in FIG. 1, the dichroic prism 7 is used for combining the three primary colors, but as shown in FIG. 7, two dichroic mirrors 70 are used.
It may be replaced with G, 70B. In the figure, 70G is a dichroic mirror for green reflection and red transmission, and 70B is a dichroic mirror for blue reflection and green / red transmission. Other components are the same as those in FIG. The method of driving the liquid crystal panel and the method of switching the polarization explained in FIGS. 3, 4 and 6 and the method of setting the row pitch of the liquid crystal panel and the polarization switching element are the first
It is similar to the embodiment of. It is clear from the description of the first embodiment that the effects of the present invention are the same in this case as well.

<Third Embodiment> In the configuration of FIG. 1, liquid crystal panels 6R, 6G and 6B and polarization switching elements 21R and 21 are used.
Although G and 21B have been described as separate elements, they may actually be integrally formed. FIG. 9 shows the configuration in that case. In FIG. 9, reference numeral 6 is a TN liquid crystal panel for image display, which is composed of liquid crystal cells 6L having polarizing plates 6P and 6A and a matrix electrode 6M. Reference numeral 21 denotes a polarization switching element, which is composed of two transparent substrates 21F and 21R, a liquid crystal layer sandwiched between them, and a row electrode 21C. The polarization switching element 21 and the liquid crystal panel 6 are integrally formed so as to be in contact with each other. By mounting three sets of elements, each of which has the liquid crystal panel and the polarization switching element integrally formed, in the same optical system as in FIGS. 1 and 7, the optical system can be downsized,
In addition, since it is not necessary to position the liquid crystal panel and the polarization switching element relative to each other when assembling the device, the assembling work is facilitated. Moreover, since the surface of the matrix 6M which is the image display surface of the liquid crystal panel and the surface of the row electrode 21C of the polarization switching element are brought close to each other, when the projected image is focused, the blurring of the row electrode 21C can be reduced. As left /
Crosstalk between right-eye images can be reduced. It should be noted that only the incident side polarization plate 6P may be separately configured for cooling the element. Since the polarizing plate 6P does not particularly have a pixel structure or the like, there is no particular need for adjustment even if it is separated.

<Modification> In the above embodiments, an example was described in which the directions of the linearly polarized light of the projection images for the right eye and the left eye were switched by 90 ° and projection was performed, but a second conventional example will be described with reference to FIG. As described above, the right-handed circularly polarized light and the left-handed circularly polarized light may be switched and projected. In this case, as shown by the broken line in the projection optical system of FIGS.
It should be inserted before this. The λ / 4 plate 22 to be inserted is arranged so that the optical axis thereof forms 45 ° with the polarization direction of the transmitted light of the polarization switching element. In addition, three λ / 4 plates are provided immediately after the polarization switching elements 21G, 21B, 21R (on the projection lens side).
If they are inserted one by one, the phase shift amount of the λ / 4 plate can be optimized according to the dominant wavelength of each primary color, which is convenient because the color change of the projection light becomes small. As for the circular polarization glasses worn by the observer, the same circular polarization glasses as shown in FIG. 11b in the conventional example may be used. The advantages of circularly polarized light projection are
As in the conventional example, crosstalk does not occur even if the observer tilts his head left and right.

In FIGS. 1 and 7, the emission side polarization plate (polarization plate 6A in FIG. 2) of the TN mode liquid crystal panels 6R, 6G and 6B may be omitted. In this case, there is a feature that only the person wearing the polarized glasses can view the projected image.
This also applies to the circularly polarized light projection described above.

In FIG. 2, the polarization axes of the incident side polarization plate 6P and the emission side polarization plate 6A of the TN mode liquid crystal panel 6 are arranged so as to be orthogonal to each other. Even if the two polarization axes are arranged in parallel, the stereoscopic image can be observed according to the present invention.

As a polarization switching element, TN (Tw
An isted Nematic) liquid crystal cell may be used. FIG. 8 is an explanatory diagram showing the operation principle of a modification (TN liquid crystal cell) of the polarization switching element used in the present invention. In the figure, the TN liquid crystal cell 21 is a transparent substrate 21F having a transparent electrode and an alignment layer on its inner surface. , 21R and a liquid crystal 21L injected between them. As shown in FIG. 8A, the liquid crystal 21 is oriented so that the major axis direction of the liquid crystal molecules is rotated by 90 ° from the substrate 21F to the substrate 21R when no voltage is applied. The light is rotated 90 ° along the twist of the liquid crystal molecules and transmitted. On the other hand, when a voltage V of a certain value or more is applied to the transparent electrode, the twisted orientation of the liquid crystal 21L disappears, and the polarization plane of the incident light Li is transmitted without rotating. Utilizing the properties of the TN liquid crystal cell as described above, no voltage is applied and voltage V is
Switching of the polarization plane can be realized by applying two states. Of course, when applying the TN liquid crystal cell to the present invention, at least one side of the transparent electrode should be periodically divided in the vertical direction. As described above, when the TN liquid crystal panel is used as the image display panel and the TN liquid crystal cell is also used as the polarization switching element, part of the liquid crystal cell manufacturing process can be shared, so that the cost of the projection display device is reduced. Further, if both the liquid crystal cells for the liquid crystal panel of the image element and the liquid crystal cells for the polarization switching element are configured by using TN liquid crystal cells having matrix electrodes in the vertical / horizontal directions, both cells can be made the same, which results in cost reduction It will become more prominent.

[0059]

As described above, according to the present invention, a novel stereoscopic image capable of displaying a parallax image for the right eye and the left eye by switching the polarized light emitted from the light valve (image display liquid crystal panel) row by row. A projection display device capable of displaying can be realized. This device is compact because it can project a stereoscopic image with a single projector, and does not require any adjustment at the time of installation such as superposition adjustment of left and right parallax images.

Further, since the output lights of a plurality of light valves are combined and projected, a sufficient number of pixels can be secured and a high-definition and high-luminance stereoscopic image can be displayed.

Further, the combined light of a plurality of light valves is expressed by λ
Since the / 4 plate converts the light into circularly polarized light that rotates in the opposite directions for the right eye and the left eye and can project the light, crosstalk between the left and right parallax images can be reduced even if the observer tilts the head to the left or right.

Further, by switching the state of the polarization switching element by the electrodes having a periodic structure so as to alternately output the images for the left eye and the right eye for each row, a highly reliable stereoscopic image without a mechanical polarization switching mechanism is provided. A projection display device for display can be realized.

Further, since the polarization of the display image of the TN mode liquid crystal can be controlled by the polarization switching element made of the ferroelectric liquid crystal which operates at high speed, it is possible to display a stereoscopic image with high contrast.

Further, since the display image of the TN mode liquid crystal can be controlled in polarization by the polarization switching element of the TN mode liquid crystal, the manufacturing process of the liquid crystal cell can be made common and a relatively inexpensive projection display device can be obtained.

Since the right eye image and the left eye image can be interlaced by the action of the light valve drive circuit, the polarization switching element and the scanning circuit, stereoscopic display with less flicker is possible.

By combining a telecentric projection lens, a light valve having the same electrode period in the vertical direction, and a polarization switching element, the display of each row can be surely sent to the right eye or the left eye, and a stereoscopic image with small crosstalk can be obtained. Display is possible.

Further, the ratio of the distance from the entrance pupil position of the non-telecentric projection lens to the light valve and the polarization switching element and the ratio of the vertical electrode cycle of the light valve and the vertical electrode cycle of the polarization switching element are equal. By doing so, it is possible to reliably send the display of each line to the right eye or the left eye, and it is possible to display a stereoscopic image with small crosstalk.

Further, since the light valve and the polarization switching element are integrally formed, the projection display device can be easily assembled, and the projection display device is compact and has a small crosstalk between the left / right parallax images. Is obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an optical system of a projection display apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement of a liquid crystal panel and a polarization switching element, which are main parts of FIG.

FIG. 3 is a configuration diagram of a drive circuit and a scanning circuit of a liquid crystal panel, a polarization switching element according to the present invention.

FIG. 4 is an explanatory diagram of operating states of the liquid crystal panel and the polarization switching element according to the present invention.

FIG. 5 is an operation explanatory diagram of a polarization switching element (EO-HW) used in the present invention.

FIG. 6 is an explanatory diagram of a method of designing a row electrode pitch of a liquid crystal panel and a polarization switching element according to the present invention.

FIG. 7 is a configuration diagram showing an optical system of a second embodiment of the projection display apparatus according to the present invention.

FIG. 8 is an operation explanatory diagram of a modification (TN liquid crystal cell) of the polarization switching element used in the present invention.

FIG. 9 is a diagram showing a configuration of an integrated liquid crystal panel / polarization switching element used in a third embodiment of the present invention.

FIG. 10 is a configuration diagram of a projection display device according to a first conventional example.

FIG. 11 is a configuration diagram of a projection display device according to a second conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 light source 6,6R, 6G, 6B light valve (first liquid crystal panel) 6M pixel electrode 6P, 6A polarizing plate 7,70B, 70G combining means 8 projection lens means 21,21R, 21G, 21B polarization switching means (second
Liquid crystal panel) 21C row electrode 22 λ / 4 plate 30 light valve drive circuit 40 scanning circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04N 9/31 C

Claims (10)

[Claims] 1. A light source, a light valve that converts illumination light emitted from the light source into linearly polarized light and modulates an in-plane polarization state according to an image signal, and a polarization direction of output light of the light valve is displayed. A projection type display device comprising: a polarization switching unit for switching each line of an image; and a projection lens unit for magnifying and projecting a light beam output from the polarization switching unit. 2. A plurality of the light valves are provided, the polarization switching means is provided on the emission side of each of the plurality of light valves, and a combining means for combining and projecting the output light of the polarization switching means is provided. The projection display device according to claim 1, wherein the projection display device is a display device. 3. A plurality of the light valves are provided, the polarization switching means is provided on the exit side of each of the plurality of light valves, and the output light of each polarization switching means is a right-handed circularly polarized light depending on the polarization switching state. Λ / convert light to left-handed circularly polarized light
2. The projection display device according to claim 1, further comprising four plates, wherein the output lights of the respective polarization switching means are combined and projected. 4. The light valve has at least pixel electrodes which are periodic in the vertical direction of a display screen, and the polarization switching means is provided with row electrodes which are periodic in the vertical direction corresponding to the pixel structure. 2. The projection display apparatus according to claim 1, wherein the polarization state of the output light of each row is alternately switched for the right eye and the left eye according to a signal applied to the electrodes. 5. The light valve comprises a first liquid crystal panel comprising a cell enclosing a TN mode liquid crystal and a polarizing plate arranged on both the illumination light incident side or the illumination light incident / exiting side, and the polarization switching means. Consists of a second liquid crystal panel with a structure in which a ferroelectric liquid crystal is sandwiched between two transparent substrates,
In the ferroelectric liquid crystal, the orientation of the liquid crystal molecules is switched between two states of state 1 and state 2 according to the polarity of the applied voltage, and in state 1, the polarization direction of the emitted light of the first liquid crystal panel is transmitted without rotating. The projection display device according to claim 1, wherein, in the state 2, the polarization direction of the emitted light of the first liquid crystal panel is rotated by 90 ° and transmitted. 6. The light valve comprises a first liquid crystal panel comprising a cell enclosing a TN mode liquid crystal and a polarizing plate arranged on both the illumination light incident side or the illumination light incident / exiting side, and the polarization switching means. Is a second liquid crystal panel having a structure in which TN mode liquid crystal is sandwiched between two transparent substrates. The TN mode liquid crystal of the second liquid crystal panel switches between two states, state 1 and state 2 according to the applied voltage. In the state 1, the light emitted from the first liquid crystal panel is transmitted without rotating the polarization direction, and in the state 2, the light emitted from the first liquid crystal panel is rotated by 90 ° and transmitted. The projection display device according to claim 1, wherein: 7. The image signal is output from a pair of image signal sources for the left eye and the right eye, and the row output of the image signal source for the left eye is L1, L2, L3, L4 ,. Ln-1, Ln, and the row output of the image signal source for the right eye is R1, R2, R3, R4, ..., Rn-
1, Rn, in the odd field, L1, R2, L for the display line from the top of the light valve downward.
Light that displays the image of 3, R4, ... Ln-1, Rn, and displays the image of R1, L2, R3, L4, ... Rn-1, Ln in the even field. A valve drive circuit is provided, and in synchronization with the display of each row of the odd field and the even field,
The scanning means for switching the state of the polarization switching means according to the eye corresponding to each row is provided.
The projection display device described. 8. The projection lens means is a telecentric lens system in which an off-axis chief ray on the light valve side is parallel to an optical axis of the projection lens means, and the light valve and the polarization switching means are arranged in a vertical direction. 2. The projection display device according to claim 1, wherein the projection display device has a periodical electrode structure, and the vertical pitches of the electrodes of the light valve and the polarization switching means are equal. 9. The projection lens means is a non-telecentric lens system, the light valve has a periodic electrode structure having a vertical pitch Pl, and the polarization switching means has a vertical pitch Pe. When the optical distance from the polarization switching means to the entrance pupil of the projection lens means is L2, and the optical distance from the light valve to the entrance pupil of the projection lens means is L1, it has a periodic electrode structure, and
2. The projection display device according to claim 1, wherein the Pl and Pe satisfy the following relationship. Pl / Pe = L1 / L2 10. The projection display device according to claim 1, wherein the light valve and the polarization switching means are in contact with each other and integrally configured.