JP2003199125A - Video projector and video projection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video projector that is much downsized and the cost of which is reduced more. <P>SOLUTION: The video projector 10 includes: a reflection type liquid crystal display element 16; a polarization switching element 17; a projection lens 18; and a synchronous circuit (not shown). The reflection type liquid crystal display element 16 and the projection lens 18 temporally and alternately project a left eye video image to be perceived by a left eye of a viewer A and a right eye video image to be perceived by the right eye of the viewer A by incident light on the basis of drive control by the synchronous circuit. Further, the polarization switching element 17 switches the light by the projection lens 18 into a light of a different kind able to be separately guided when the left eye video image is projected or when the right eye video image is projected on the basis of the drive control by the synchronous circuit. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image projection apparatus and an image projection method for projecting an image so that a viewer can see the image three-dimensionally.

[0002]

2. Description of the Related Art Conventionally, there has been known a three-dimensional image projection apparatus which projects an image so that a viewer can see the image three-dimensionally. There are mainly the following two types of stereoscopic image projection system.

One is called a polarization method,
This is a method of projecting an image for the left eye and an image for the right eye by using two polarized lights orthogonal to each other. For example, as shown in FIG. 5, a conventional polarization type stereoscopic projection apparatus 1 includes a left projector L that projects an image for the left eye and a right projector R that projects an image for the right eye. Has been done. The left and right projectors L and R each include an ultra-high pressure mercury lamp 2, an integrator 3, a DMD element 5, and a projection lens 6.

The light emitted from the ultra-high pressure mercury lamp 2 is converted into a uniform light flux by the integrator 3,
After passing through the condenser lens and the mirror, the DMD element 5 is illuminated. The light incident on the DMD element 5 is reflected and modulated by the DMD element 5. Here, in the left projector L, light is modulated based on the image information for the left eye,
In the right projector R, light is modulated based on the image information for the right eye.

The light reflected by the DMD element 5 is projected on the screen 7 by the projection lens 6. Here, in each of the left and right projectors L and R, light is projected after being converted into polarized light whose polarization directions are orthogonal to each other. As a result, the left-eye image and the right-eye image are simultaneously projected on the screen 7 by the two polarized lights whose polarization directions are orthogonal to each other.

An observer A wears polarizing glasses G having polarizing plates G1 and G2 attached to the left and right so that their orientations are orthogonal to each other, and views the image projected on the screen 7. As a result, the viewer A can perceive the left-eye image with the left eye and the right-eye image with the right eye through the polarizing plates G1 and G2. You can see

Another system of the stereoscopic image projection apparatus is called a time division system in which a left eye image and a right eye image are projected alternately in time. The viewer can see the image three-dimensionally by wearing glasses with a liquid crystal shutter that are switched in synchronism with the switching of the projection of the left-eye image and the right-eye image.

[0008]

However, the above-mentioned polarization method has a problem that the size of the apparatus becomes large because it requires the right and left projectors, respectively. Furthermore, in order to match the angle of view of the left and right projectors,
It was necessary to perform adjustment work. On the other hand, the above-mentioned time division method has an advantage that an image can be projected by one projector. However, since the liquid crystal shutter of the glasses with a liquid crystal shutter has to be controlled and driven according to the switching of the projection of the image for the left eye and the image for the right eye, the cost of the glasses is higher than that of the polarized glasses used in the polarization method. There was a problem that it would end up. An object of the present invention is to provide a video projection device that is smaller and that can keep costs down.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 is, for example, as shown in FIG. 1, by projecting light so that the left eye of an observer (A) Projection means (reflective liquid crystal element 16, projection lens 1) for alternately projecting a left-eye image to be perceived and a right-eye image to be perceived by the viewer's right eye in time.
8, a synchronizing circuit (not shown), and the light projected by the projection means can be separately guided when the left-eye image is projected by the projection means and when the right-eye image is projected by the projection means. An image projection device (10) comprising: a light switching unit (a polarization switching element 17, a synchronizing circuit (not shown)) for switching to different types of light.

Here, "different kinds of light capable of being separated and guided" mean two kinds of light which can separate and guide the respective lights when these lights are projected at the same time. To do. Specifically, for example, two types of polarized light having mutually different polarization directions, two types of polarized light having mutually orthogonal polarization directions, two types of light having different spectral distributions (lights having different colors), and the like can be mentioned.

According to the first aspect of the present invention, the different types of lights that can be separated and guided by the light switching means are projected by the projection means, and the left-eye image and the right-eye image are generated. It is projected alternately in time. Therefore, by separately guiding the left-eye image and the right-eye image, which are projected alternately in time, to the left eye and the right eye of the viewer, the viewer can see the image three-dimensionally. .

As described above, according to the invention of claim 1,
Since the image projection device includes the projection means, the left-eye image and the right-eye image are projected alternately in time. Therefore, unlike the conventional polarization type stereoscopic image projection device that requires the left and right projectors, it is not necessary to project the left-eye image and the right-eye image by separate projection means. Therefore, only one projection means for projecting an image can be used, and the image projection device can be downsized. Also, unlike the conventional polarization type stereoscopic image projection apparatus, there is no need to perform adjustment work or the like for matching the angle of view of the projector. Further, since the image projection apparatus of the present invention includes the light switching means, the left-eye image and the right-eye image are projected by projecting different kinds of light that can be separately guided. Therefore, unlike a conventional mere time-division type stereoscopic image projection device, it is not necessary to use eyeglasses with a liquid crystal shutter or the like that are synchronously driven to switch the projected left-eye image and right-eye image. Therefore, it is possible to further reduce the cost as compared with the conventional time-division stereoscopic image projector. As described above, according to the first aspect of the present invention, since the time-division projection means and the light switching means are both provided, the image projection apparatus can be downsized and the cost can be reduced.

It is to be noted that, in order for the viewer to see the image projected by the image projector according to claim 1 in three dimensions, the left-eye image and the right-eye image are viewed by the viewer. The means for separately guiding each of the left eye and the right eye is not particularly limited, but as an example, an optical system that can be worn by a viewer and has different optical properties from each other is provided on the left and right, respectively. Eyeglasses. Specific examples of the spectacles include spectacles in which polarizing plates whose alignment directions are orthogonal to each other are provided on the left and right.

According to a second aspect of the present invention, in the image projection apparatus according to the first aspect, the light switching means switches the light into two types of polarized light having different polarization directions.

According to the second aspect of the invention, the light projected by the projection means is switched by the light switching means to two types of polarized light having different polarization directions, and the light is projected by the projection means. , A left-eye image and a right-eye image are respectively projected. Therefore, unlike a so-called anaglyph-type image projection device that projects a left-eye image and a right-eye image by projecting light of different colors, the left-eye image and the right-eye image are respectively polarized by polarization. Can be projected in full color. Therefore,
Viewers can see chromatic stereoscopic images with more accurate hues.

Here, as the polarization switching element used for the light switching means, specifically, for example, a transmission type liquid crystal element,
A reflective liquid crystal element, an electro-optic crystal element, and the like can be given, but the invention is not particularly limited to these examples, and any element that can switch the polarization direction of light can be applied.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the image projection apparatus described above, the projection means includes a reflection type image display element (reflection type liquid crystal element 16 in FIG. 1) that reflects and modulates light, and is reflected and modulated by this reflection type image display element. It is characterized by projecting light. Here, as the reflective image display element, specifically, for example, the reflective liquid crystal element according to claim 5 or D
Examples include MDs, but the present invention is not limited to these examples, and any element that reflects and modulates light can be applied.

According to the third aspect of the present invention, the light reflected and modulated by the reflection type image display element is projected by the projection means, whereby the image is projected. Therefore, as compared with the case where light is modulated using a transmissive liquid crystal element that transmits and modulates light, the loss of light at the time of light modulation can be suppressed to a relatively small amount, and the modulation speed is high. Therefore, it is possible to improve the image quality by making the projected moving image more responsive and bright.

According to a fourth aspect of the invention, in the image projection apparatus according to the third aspect, the reflection type image display element is a reflection type liquid crystal element (LCOS (Liquid Crystal On Silicon) element) or DMD (Digital Micromirror Device). Is characterized in that. According to the invention of claim 4,
Since the reflection type image display element is a reflection type liquid crystal element or a DMD, light can be modulated by high-speed switching. Therefore, the flicker of the projected image can be suppressed to be relatively small.

According to a fifth aspect of the present invention, different types of light that can be separated and guided are alternately projected in time so that a left-eye image to be perceived by the left eye of a viewer and the viewing. And a right-eye image that should be perceived by the right eye of a person is projected alternately in time.

According to the fifth aspect of the invention, different kinds of light that can be separated and guided are alternately projected in time, and the left-eye image and the right-eye image are alternately arranged in time. Is projected. Therefore, the left-eye image and the right-eye image, which are alternately projected in time, are separately guided to the left eye and the right eye of the viewer, so that the viewer can see the image in three dimensions. .

As described above, according to the invention of claim 5,
Since the left-eye image and the right-eye image are projected alternately in time, unlike the conventional stereoscopic image projection by the polarization method that requires the left and right projectors, respectively, the left-eye image and the right-eye image are projected. Need not be projected by separate projection means. Therefore, only one projection means for projecting an image can be used, and the image projection device can be downsized. In addition, since different left and right eye images are projected by projecting different types of light that can be separated and guided, unlike the conventional time-division stereoscopic image projection, the left eye image is projected. It is not necessary to use glasses with a liquid crystal shutter that are driven in synchronization with switching between the image and the image for the right eye, and it is only necessary to wear inexpensive polarized glasses. Therefore, the cost can be kept lower than that of the conventional time division method. As described above, according to the fifth aspect of the invention, it is possible to reduce the size of the image projection apparatus and reduce the cost.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

[First Embodiment] A video projection apparatus according to a first embodiment of the present invention is a projector applicable to a stereoscopic video system for allowing a viewer to perceive a stereoscopic video. As shown in FIG. 1, the stereoscopic video system S includes the video projection device 10 according to the first embodiment, a polarization maintaining screen 7, and polarizing glasses G.

The optical engine unit in the image projection apparatus 10 shown in FIG. 1 comprises an ultra-high pressure mercury lamp 11 and a color wheel 1.
2, an integrator 13, a polarization conversion element 14, a polarizing plate (not shown), a polarization beam splitter 15, a reflective liquid crystal element 16, a polarization switching element 17, and a projection lens 1
8 and a synchronizing circuit (not shown).

The ultra-high pressure mercury lamp 11 is used for the image projection device 1.
0 serves as a light source of projected light. Further, the color wheel 12 transmits light to R (red), G (green), and B.
It is a rotary division color filter for switching to any one of (blue) monochromatic light. A synchronization circuit is connected to the color wheel 12, and the rotation of the color wheel 12 is controlled by this synchronization circuit. Also,
The integrator 13 converts the emitted light flux into a uniform illumination light flux.

The polarization conversion element 14 is a known element that converts light into linearly polarized light in a predetermined direction. In the image projection device 10, the polarization conversion element 14 is installed in the optical engine unit so as to convert the light passing through the integrator 13 into S-polarized light. A polarization plate (not shown) is provided between the polarization conversion element 14 and the polarization beam splitter 15. The polarizing plate is installed in the optical engine unit so that its orientation direction matches the direction of transmitting the S-polarized light converted by the polarization conversion element 14. The polarization beam splitter 15 is a reflection surface 15 that reflects S-polarized light and transmits P-polarized light.
It is a known optical component that has a and is capable of splitting light into S-polarized light and P-polarized light.

The reflective liquid crystal element 16 is a so-called LCOS (Liquid Crystal On Silicon) capable of high-speed switching.
con) element and so on. Reflective liquid crystal element 16
A video signal input and a synchronizing circuit are connected to.
The reflective liquid crystal element 16 generates an image pattern of any of R, G, B of the left image and R, G, B of the right image sequentially supplied from the image output circuit according to the synchronizing signal from the color wheel 12. , The illumination light is modulated and reflected. Here, the number of reflective liquid crystal elements 16 included in the optical engine unit is one. That is, the image projection device 1
Reference numeral 0 is a so-called single-plate type projector.

The polarization switching element 17 is composed of, for example, a transmissive liquid crystal element. A synchronization circuit is connected to the polarization switching element 17. Polarization switching element 1
7 is, according to the synchronization signal supplied from the synchronization circuit,
Processing for switching the polarization direction of light is performed. That is, the polarization switching element 17 and the synchronization circuit connected to the polarization switching element 17
It is an optical switching means for switching to different types of light that can be separated and guided by a polarizing plate or the like. The projection lens 18 enlarges and projects the projection light on the polarization maintaining screen 7.

The synchronizing circuit (not shown) is the color wheel 1.
2, the reflective liquid crystal element 16 and the polarization switching element 17,
The processing for driving control is performed in synchronization with each other.
Specifically, the synchronization circuit sequentially switches the light emitted from the ultra-high pressure mercury lamp 11 to monochromatic light at predetermined time intervals (for example, every 3 ms), for example, in the order of R, G, and B.
Processing for controlling the rotation of the color wheel 12 is performed. Also,
The synchronizing circuit synchronizes the rotation control of the color wheel 12 with each of the R, G, and B image signals to reflect the liquid crystal element 1.
6 is sequentially supplied to the reflective liquid crystal element 16 to perform the modulation processing of the R, G, and B monochromatic lights in sequence.

When the image projection device 10 is applied to the stereoscopic image system S, the synchronizing circuit uses R, G, and
A process of sequentially supplying the respective video signals of B and the video signals of R, G, and B of the right-eye video to the reflective liquid crystal element 16 is performed temporally alternately. Here, the image for the left eye,
The image for the right eye is an image that should be perceived by each of the left eye and the right eye of the viewer A in order to allow the viewer A to see the image stereoscopically in the stereoscopic image system S. Is. In addition, the synchronization circuit supplies a synchronization signal to the polarization switching element 17 in synchronization with the supply of the video signal to the reflective liquid crystal element 16 so that the reflective liquid crystal element 16 receives the light based on the video signal of the image for the left eye. A process for driving and controlling the polarization switching element 17 is performed so as to switch light in different polarization directions orthogonal to each other between when performing the modulation process and when performing the light modulation process based on the image signal of the right-eye image. To do.

The polarization maintaining screen 7 of the stereoscopic image system S is a conventionally well-known screen which can well maintain the polarization state of light. In addition, the polarized glasses G are for the viewer A.
However, it is mounted and used when watching the image projected on the polarization maintaining screen 7. The polarized glasses G include
A polarizing plate G1 is provided on each of the left side and the right side viewed from the viewer A side.
-G2 is attached. The polarizing plate G1 is attached such that its alignment direction matches the polarization direction of the polarized light switched by the polarization switching element 17 when the reflective liquid crystal element 16 performs light modulation processing based on the image signal of the image for the left eye. There is. Further, the polarizing plate G2 is attached so that its alignment direction matches the polarization direction of the polarized light switched by the polarization switching element 17 when the reflective liquid crystal element 16 performs light modulation processing based on the image signal of the image for the right eye. Has been.

Next, how the light travels in the stereoscopic image system S will be described. The radiant light flux emitted from the ultra-high pressure mercury lamp 11 enters the color wheel 12 and
2 switches to any one of R, G, and B monochromatic light. The emitted light switched to the monochromatic light enters the integrator 13, and the integrator 13 causes
It is converted into a uniform light flux. The light converted into a uniform light flux enters the polarization conversion element 14 and is converted into S-polarized light by the polarization conversion element 14. The light converted into S-polarized light enters a polarizing plate (not shown), and the polarizing purity is improved by the polarizing plate.

The S-polarized light whose polarization purity has been improved by the polarizing plate is vertically incident on the polarization beam splitter 15 and is reflected by the reflecting surface 1.
The light is reflected by 5 a and vertically incident on the reflective liquid crystal element 16. The S-polarized light that has entered the reflective liquid crystal element 16 is modulated by the reflective liquid crystal element 16 on the basis of the R, G, or B video signal of either the left-eye video image or the right-eye video image. It is reflected and converted into P-polarized light.

As described above, the synchronizing circuit supplies R, G, and B image signals to the reflective liquid crystal element 16 in synchronization with the rotation control of the color wheel 12, so that the color wheel 12 controls the R signal. When switched to monochromatic light, the light is modulated based on the R image signal, when switched to G monochromatic light, the light is modulated based on the G video signal, and when switched to B monochromatic light. Light is modulated based on the B video signal.

The light modulated and reflected by the reflective liquid crystal element 16 returns to the polarization beam splitter 15 and is vertically incident on it. Since this light is P-polarized, the reflecting surface 1
After passing through 5a, it exits the polarization beam splitter 15 and enters the polarization switching element 17. The polarization direction of the light incident on the polarization switching element 17 is switched by the polarization switching element 17 as necessary.

Here, as described above, the synchronizing circuit supplies the synchronizing signal to the polarization switching element 17 in synchronization with the supply of the video signal to the reflection type liquid crystal element 16, so that the reflection type liquid crystal element 16 makes the left side. Light is modulated in different polarization directions orthogonal to each other when the light is modulated based on the video signal of the eye image and when the light is modulated by the reflective liquid crystal element 16 based on the video signal of the right image. Can be switched.

The light whose polarization direction is switched by the polarization switching element 17 is enlarged and projected on the polarization maintaining screen 7 by the projection lens 18. Thus, when the reflection-type liquid crystal element 16 performs light modulation processing based on the video signal of the left-eye video image, the left-eye video image is projected, and the light modulation is performed based on the video signal of the right-eye video image. When the processing is performed, the right-eye image is projected. That is, the reflective liquid crystal element 16, the synchronizing circuit connected to the reflective liquid crystal element 16, and the projection lens 18 are projection means for projecting a left-eye image and a right-eye image, respectively.

Here, as described above, the alignment direction of the polarizing plate G1 of the polarizing glasses G matches the polarization direction of the light projected when the image for the left eye is projected, and the alignment of the polarizing plate G2. The direction matches the polarization direction of the projected light when the right-eye image is projected. Therefore, when the viewer A wears the above-mentioned polarized glasses G and views the image projected on the polarization maintaining screen 7 by the image projection device 10, the viewer A finds that the image for the left eye is projected. , Polarizing plate G
When the left-eye image is perceived by the left eye via 1 and the right-eye image is projected, the right-eye image is perceived by the right eye via the polarizing plate G2.

Next, an image projection method for sequentially projecting images by the image projection device 10 in the stereoscopic image system S will be described. In the image projection method of sequentially projecting images, light is emitted by the ultra-high pressure mercury lamp 11, and the color wheel 12, the reflective liquid crystal element 16, and the polarization switching element 17 are synchronized by a synchronizing circuit as follows, for example. Drive control.

That is, for example, as shown in FIG.
When the images are sequentially projected in the order of the th video (n-th Scene), the (n + 1) th video ((n + 1) th Scene), the (n + 2) th video ((n + 2) th Scene) ... The circuit drives the color wheel 12 to rotate, and as shown in the lower row in the figure,
The light emitted from the ultra-high pressure mercury lamp 11 is sequentially switched to monochromatic light in the order of R, G, and B at ms intervals.

Further, in synchronization with the drive control of the color wheel 12 described above, a reflection type liquid crystal element 16 is provided by a synchronizing circuit.
The supply of the R, G, B video signals of the left-eye video and the supply of the R, G, B video signals of the right-eye video are alternately performed in time.

Specifically, as shown in FIG. 2, the R of the left-eye image (Left) for allowing the reflective liquid crystal element 16 to stereoscopically perceive the n-th image by the synchronizing circuit.
Image signal, G image signal, and B image signal are supplied in this order at 3 ms intervals, and then the R image of the right eye image (Right) for stereoscopically perceiving the nth image. Signal, G video signal, B video signal in this order for 3 m
Supply at s intervals. Next, similarly to the case of the n-th video, the R, G, and B video signals of the left-eye video are sequentially supplied to the (n + 1) -th video, and subsequently, the R of the right-eye video, G and B video signals are sequentially supplied. By repeating this, the left-eye image signal and the right-eye image signal are sequentially supplied to the reflective liquid crystal element 16 in the order of left, right, left, right ,.
The reflective liquid crystal element 16 is caused to sequentially perform light modulation processing.

Here, the repetition frequency of the light modulation process based on the video signal of the left-eye image and the light modulation process based on the video signal of the right-eye image by the reflection type liquid crystal element 16 is 50 to 60 Hz. , And more preferably, a reflection type liquid crystal element 1 for displaying a video signal by a synchronizing circuit so that the frequency becomes 60 Hz or more.
It is preferable to feed 6 sequentially.

Further, in synchronization with the drive control of the reflective liquid crystal element 16 described above, a synchronizing signal is sequentially supplied to the polarization switching element 17 by a synchronization circuit, and the polarization switching element 17 is sequentially switched in the polarization direction of light. Let Thereby, as shown in the upper row in FIG.
In synchronism with the light modulation processing based on the video signals of the left-eye video image and the right-eye video image, the switching is sequentially performed in directions orthogonal to each other.

By the above synchronous drive control, the light emitted by the ultra-high pressure mercury lamp 11 is transmitted to the color wheel 12
Are sequentially converted into R, G, and B monochromatic light, and are sequentially modulated by the reflective liquid crystal element 16 in the order of left-eye image, right-eye image, left-eye image, right-eye image, ... While sequentially switching the polarization direction of light by the polarization switching element 17,
It is projected onto the polarization maintaining screen 7 by the projection lens 18. As a result, polarized lights whose polarization directions are orthogonal to each other are projected alternately in time, and a full-color left-eye image and right-eye image in which R, G, and B lights are mixed in time division Image is alternately projected onto the polarization maintaining screen 7.

As described above, according to the image projecting apparatus 10 of the first embodiment and the image projecting method by the image projecting apparatus 10, the polarization switching elements 17 alternately switch the polarizations with respect to each other. Polarized light whose directions are orthogonal to each other
By being projected by the projection lens 18, the left-eye image and the right-eye image are projected alternately in time.
Therefore, the viewer A, by wearing the polarizing glasses G, a left-eye image that is separately guided to the left eye by the polarizing plate G1, and a right-eye image that is separately guided to the right eye by the polarizing plate G2, The images can be viewed three-dimensionally by alternately perceiving each other.

Since the viewer A is made to stereoscopically perceive the image in this manner, the left-eye image and the right-eye image are projected simultaneously, unlike the conventional polarization type stereoscopic image projection device shown in FIG. There is no need for the left and right projectors L and R to operate. Therefore, a single optical engine unit for projecting an image can be used, so that the device can be further downsized as compared with the conventional polarization type stereoscopic image projecting device.

Since the left-eye image and the right-eye image are projected by projecting two polarized lights whose polarization directions are orthogonal to each other, the viewer A wears the polarized glasses G and the polarization maintaining screen. By viewing the image projected on the screen 7, the image can be viewed three-dimensionally. Therefore, unlike the projection of stereoscopic images by the conventional time division method,
It is not necessary to use eyeglasses with a liquid crystal shutter that is driven in synchronization with switching of the projected image, and it is only necessary to wear inexpensive polarized eyeglasses. Therefore, the cost of the stereoscopic image system S can be further suppressed.

As described above, according to the image projection apparatus 10 of the first embodiment, the synchronizing circuit, the reflective liquid crystal element 16 and the polarization switching element 17 which are synchronously driven and controlled by the synchronizing circuit are provided. As a result, the image projection apparatus 10 can be downsized and the cost can be reduced.

Further, by projecting the polarized light, the full-color left-eye image and the right-eye image are respectively projected, so that different colors of light are projected to form the left-eye image and the right-eye image, respectively. As compared to an anaglyph-type image projection device that projects images, the viewer A can see a chromatic three-dimensional image with more accurate hue.

Further, since the reflection type liquid crystal element 16 performs the light modulation processing, the loss of light at the time of light modulation is relatively small as compared with, for example, a transmission type liquid crystal element which transmits and modulates light. To be Therefore, the projected image can be made brighter and the image quality can be improved.

Further, since the light can be modulated by the high-speed switching of the reflective liquid crystal element 16, the flicker of the projected image can be suppressed to a relatively small level. In particular, when the repetition frequency of the light modulation processing based on the video signal of the left-eye image and the light modulation processing based on the video signal of the right-eye image is set to 50 to 60 Hz, the viewer A feels. The flicker of the image can be suppressed to a lesser extent, and further,
When the frequency is set to 60 Hz or higher, the viewer A can see the stereoscopic image with almost no flicker of the image.

Further, the image projection device 10 sequentially converts light into R, G, B monochromatic lights by the color wheel 12,
Since this is a single-plate type projector that performs light modulation processing by one reflective liquid crystal element 16, the optical system can be simplified compared to a three-plate type projector that requires three elements that perform light modulation. The size of the entire apparatus can be made more compact and the weight can be reduced.

Further, in the image projection apparatus 10 having the above-described configuration, the image signals for the left eye and the image for the right eye are not discriminated, and the image signals are sequentially supplied to the reflection type liquid crystal element 16 by the synchronizing circuit to generate the light. By performing the modulation process and projecting the image without performing the process of switching the polarization direction of the light by the polarization switching element 17, it is possible to project a normal two-dimensional image. Therefore, the frequency of use of the image projection device 10 can be improved as compared with a dedicated projector that projects only stereoscopic images.

In the first embodiment, FIG.
Not limited to the example shown in FIG. 3, the image may be sequentially projected by performing the synchronous drive control by the synchronous circuit as in the example shown in FIG.

In the example shown in FIG. 3, as shown in the bottom row of the drawing, the synchronizing circuit causes
The R, G, B video signals for the left-eye video are sequentially supplied at 3 ms intervals, and subsequently the R, G, B video signals for the right-eye video are sequentially supplied. Next, regarding the (n + 1) th video,
The R, G, and B image signals of the right-eye image are sequentially supplied, and subsequently, the R, G, and B image signals of the left-eye image are sequentially supplied. Next, for the (n + 2) th image, the R, G, and B image signals of the left-eye image are sequentially supplied, and subsequently, the R, G, and B image signals of the right-eye image are sequentially supplied. By repeating this, the video signals of the left-eye image and the right-eye image are sequentially supplied to the reflective liquid crystal element 16 in the order of left, right, right, left, left, right ... The light modulation processing is sequentially performed.

In synchronization with the drive control of the reflective liquid crystal element 16 described above, the polarization switching element 17 is caused to sequentially perform switching processing of the polarization direction of the light, and as shown in the upper row in FIG. Are sequentially switched in directions orthogonal to each other in synchronization with the light modulation processing based on the video signals of the left-eye image and the right-eye image.

According to the drive control example shown in FIG. 3, the nth,
The switching processing of the polarization direction of the polarization switching element 17 is shown in FIG. 2 while switching the projection of the (n + 1) th, (n + 2) th ... It can be slower than the drive control example shown. Therefore, the high-speed switching of the image can be performed while using the polarization switching element 17 having a slower switching speed, so that the cost of the polarization switching element 17 can be kept low.

The polarization switching element 17 is a transmissive liquid crystal element, but it is not limited to this as long as it can switch the polarization direction of light. For example, LCOS or the like. The reflection type liquid crystal device, the device using electro-optic crystal, or the like may be used.

Although the reflection type liquid crystal element 16 is used for light modulation, the present invention is not limited to this, and for example, a DMD (Digital Micromirror Device) capable of high-speed switching.
Other types of reflective image display elements, such as, may be used. In addition, instead of the reflective liquid crystal element 16, a DMD
Also in the case of using, it is desirable to provide the polarization conversion element 14 between the light source and the DMD and make the illumination light incident on the DMD into linearly polarized light. In addition, LCOS, DMD
Not limited to the reflection type image display element such as the above, other image display elements such as a transmission type liquid crystal display element may be used to modulate the light.

Further, the image projection apparatus 10 is a single plate type projector, but the present invention is not limited to this, and the present invention can be applied to a three plate type projector or the like.
Further, the configuration of the optical engine unit of the image projection device 10 is not limited to the above-described configuration, and can be appropriately changed without departing from the spirit of the present invention. Also,
The present invention can be applied to the front projector, rear
It is needless to say that the projector can be applied without distinction.

[Second Embodiment] As shown in FIG.
The image projection device 20 of the second embodiment is configured to include an illumination light source device 21 as a light source of projection light. The same components as those of the video projection device 10 according to the first embodiment shown in FIG. 1 are designated by the same reference numerals in FIG. 4, and detailed description thereof will be omitted.

The illumination light source device 21 includes R, G, and B light sources 22, 23, and 24, each including a plurality of R, G, and B light emitting diodes (hereinafter, abbreviated as LEDs).
The color synthesizing prism 25 that synthesizes the radiated light emitted from each of the light sources 22, 23, and 24 and guides it to the integrator 13 side. Light source 22 ・ 23 ・
The LEDs that make up 24 are connected to a synchronization circuit (not shown), and in accordance with a synchronization signal supplied from the synchronization circuit,
The light emission of R, G, and B is sequentially repeated by the switching operation.

As described above, according to the image projecting apparatus 20 of the second embodiment, the R, G, B light sources 22, 23, and 24, which are LEDs, are provided as the light sources of the projection light. As a characteristic of the LED, there is no problem in performing the switching process of R, G, and B in several milliseconds. Therefore, unlike the image projector 10 of the first embodiment that uses the ultra-high pressure mercury lamp 11, it is not necessary to provide the color wheel 12. Unlike bubble lamps such as ultra-high pressure mercury lamps, LEDs do not emit ultraviolet rays or strong infrared rays.
The configuration of the illumination optical system can be further simplified.

[0066]

According to the first aspect of the present invention, since the present video projection apparatus is provided with the projection means for projecting alternately in time, the left eye video and the right eye video are projected by separate projection means. You don't have to. Therefore, only one projection means for projecting the image can be used, and the image projection device can be downsized. Further, since the image projection device is provided with the light switching means, unlike the conventional time-division stereoscopic image projection device,
It is not necessary to use glasses with a liquid crystal shutter that are driven synchronously to switch the projected image, and inexpensive polarizing glasses may be worn. Therefore, the cost can be kept low as compared with the conventional time division method. Therefore, by providing both the projection means and the light switching means, it is possible to reduce the size of the image projection apparatus and reduce the cost.

According to the second aspect of the present invention, since it is possible to project two kinds of polarized light having different polarization directions from each other, the polarized glasses are worn by projecting the left-eye image and the right-eye image. A viewer can perceive a stereoscopic image.

According to the third aspect of the invention, since the light is modulated by the reflection type image display element, the light loss at the time of light modulation can be suppressed relatively small. Therefore, the projected image can be made brighter and the image quality can be improved. According to the invention described in claim 4, the light can be modulated by the high-speed switching, so that the flicker of the projected image can be suppressed to be relatively small. According to the invention described in claim 5, the image projection apparatus can be downsized and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating a stereoscopic video system including a video projection device according to a first embodiment.

FIG. 2 is a diagram for explaining an example of synchronous drive control of the video projection apparatus in FIG. 1 by a synchronous circuit.

3 is a diagram for explaining another example of synchronous drive control of the video projection apparatus in FIG. 1 by a synchronous circuit.

FIG. 4 is a schematic configuration diagram showing a video projection device according to a second embodiment.

FIG. 5 is a schematic configuration diagram showing a conventional stereoscopic image projection device.

[Explanation of symbols]

10 image projection device 16 reflective liquid crystal element (projection means, reflective image display element) 17 polarization switching element (light switching means) 18 projection lens (projection means) A viewer

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Claims (5)

[Claims] 1. A left eye image to be perceived by a viewer's left eye and a right eye image to be perceived by the viewer's right eye are temporally alternated by projecting light. And a projection means for projecting the left eye image by the projection means,
An image projecting device comprising: a light switching unit that switches the light projected by the projecting unit to different kinds of light that can be separately guided when the image for the right eye is projected. 2. The image projection apparatus according to claim 1, wherein the light switching means switches the light into two types of polarized light having mutually different polarization directions. 3. The projection means includes a reflection type image display element that reflects and modulates light, and projects the light reflected and modulated by the reflection type image display element. Alternatively, the video projection device described in 2. 4. The image projection apparatus according to claim 3, wherein the reflective image display element is a reflective liquid crystal element or a DMD (Digital Micromirror Device). 5. A left-eye image to be perceived by a left eye of a viewer and a left eye image to be perceived by the right eye of a viewer by projecting mutually different kinds of light that can be separated and guided alternately in time. A method for projecting an image, characterized in that the image for the right eye to be projected is alternately projected in time.