JP2002189194A - Optical modulating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To independently modulate a light of the different polarized light, while reducing cross talk and a stray light. SOLUTION: An optical modulating equipment which spatially modulates the luminance of the incident light from the light source is provided with, a polarized light separating element (20) where the light of the component of the polarized light of a 1st incident light is reflected, and the light of the component of a 2nd polarized light orthogonal to the 1st polarized light passes through, a 1st reflection type optical modulation element (40) turning the polarization direction of the light of the component of the reflected 1st polarized light, and a 2nd reflection type optical modulation element (41) turning the polarization direction of the light of the component of the transmitted 2nd polarized light. The light modulated with the 1st reflection type optical modulation element (40) passes through, and the light modulated with the 2nd reflection type optical modulation element (41) is reflected and emitted in the same direction as the light which is modulated with the 1st reflection type optical modulation element (40). Thus, luminance modulation of the two different polarized components of incident light is spatially independently carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology effective when applied to the field of displays and optical logic circuits for displaying an image by spatially modulating luminance.

[0002]

2. Description of the Related Art As an element for spatially modulating light, there is an element such as a liquid crystal display (LCD) which uses an optically active liquid crystal and changes the orientation of the liquid crystal by an electric field to change the polarization direction of the light. Has been put to practical use. In such an element, the direction of polarization of external light can be adjusted through a polarizing filter or the like, and an electric field can be applied to each pixel to change the direction of polarization. An image or the like is displayed by extracting the emitted light as a change in luminance.

[0003]

However, such an apparatus uses only one-directional polarization of incident light, and orthogonal light components are discarded at the stage of incidence. In the conventional light modulation method and apparatus, it is not possible to use the discarded light component to include unique image information in orthogonally polarized light. An object of the present invention is to provide a technique capable of independently modulating light of different polarizations with less crosstalk and stray light. The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0004]

The following is a brief description of the outline of the invention disclosed in the present application.
According to a first aspect of the present invention, in a light modulation device that spatially modulates luminance of incident light from a light source, light of a first polarization component of the incident light is reflected and a second light orthogonal to the first polarization is reflected. A polarization separation element having a polarization separation surface through which light of the polarization component is transmitted, and a polarization separation element which is placed at a position where the light of the first polarization component reflected by the polarization separation surface is guided, and A first reflection-type light modulation element that rotates the polarization direction of the component light, and a second polarization component that is located at a position where the light of the second polarization component transmitted through the polarization separation surface is guided. A second reflection-type light modulation element for rotating the polarization direction of the light, and the light modulated by the first reflection-type light modulation element is again incident on the polarization splitting surface, and the first polarization Only the light of the polarization component orthogonal to the light of the component The modulated light is incident on the polarization splitting surface again, and only the light of the polarization component orthogonal to the light of the second polarization component is reflected and the light is modulated by the first reflection type light modulation element. In the same direction, two different polarization components of the incident light are spatially modulated independently of each other.

According to the first aspect of the invention, since two different polarization components of the incident light can be spatially modulated independently of each other, image information by light can be doubled.

According to a second aspect of the present invention, there is provided an optical modulator for spatially modulating the brightness of incident light from a light source, comprising: a polarization splitting element having first, second, third and fourth polarization splitting surfaces; The first polarized light component of the incident light is reflected by the first polarization splitting surface, and the reflected first polarized light component is:
A first reflection-type light modulation element that is reflected by the second polarization splitting surface and rotates the polarization direction at a position where the light of the reflected first polarization component is guided; 1
The second polarized light component orthogonal to the first polarized light component transmitted through the polarized light separating surface further passes through the fourth polarized light separating surface, and the transmitted second polarized light component A second reflection-type light modulation element that is placed at a position where light is guided and spatially rotates the polarization direction, and the light of the first polarization component of the incident light is a first polarization separation surface. And the light of the second polarized light component is transmitted, and the light of the first polarized light component is further reflected by a second polarization splitting surface, and is reflected by the first reflection type light modulation element. The incident and modulated light is reflected again on the second polarization splitting surface, and transmits only the light of the polarization component orthogonal to the light of the first polarization component. And the light of the component of the second polarization transmitted through the first polarization separation surface passes through the fourth polarization separation surface. And the reflected light is again incident on the fourth polarization splitting surface, and only the light of the polarization component orthogonal to the light of the second polarization component is reflected. The light reflected by the third polarization splitting surface and emitted in the same direction as the light modulated by the first reflection-type light modulation element independently spatially modulates two different polarization components of the incident light. Is what you do.

According to the second aspect, the light of the first polarized light (S-polarized light) and the light of the second polarized light (P-polarized light) emitted from the light source are a plurality of polarized light separating surfaces (second polarized light, respectively). (First, second, third, and fourth polarization splitting surfaces), each of which is reflected and transmitted twice, so that the first polarized light and the second polarized light are separated well, and the first and second reflected light beams are reflected. The contrast of each image of the modulation element can be improved.

According to the second aspect, the two different polarized components of the incident light are spatially modulated independently, and the modulated output light is enlarged and projected on a screen or the like, thereby enlarging the image. You can see it.

In the first or second aspect of the present invention, an example of displaying a black-and-white image has been described. Of course, the light source is spectrally separated in advance by a dichroic mirror, a color filter, or the like, and the separated light is converted by a plurality of light modulation elements. Color display is also possible by modulating and synthesizing with a dichroic prism or the like.
Hereinafter, the present invention will be described in detail with reference to the drawings together with embodiments (examples) according to the present invention.

[0010]

(Embodiment 1) FIG. 1 is a schematic diagram showing a schematic configuration of an optical modulation device according to Embodiment 1 of the present invention. The light modulation device according to the first embodiment is an application of the present invention to a liquid crystal display. As shown in FIG.
1, a polarization beam splitter (polarization separation element having a polarization separation surface) 20, a reflection type liquid crystal panel (first reflection type light modulation element) 40 for changing the polarization direction of incident light for each pixel, and a pixel. And a liquid crystal panel (second reflection type light modulation element) 41 for changing the polarization direction of the incident light for each.

In the first embodiment, two independent images can be viewed by using the polarized glasses 200, and a stereoscopic image can be displayed by displaying a parallax image.

That is, in FIG. 1, light 100 emitted from a light source 10 is incident on a polarization beam splitter 20 having a polarization splitting surface 21, and light 101 of S-polarized light (first polarized light) is converted to a polarization splitting surface 21. Reflected by P-polarized light (second polarized light)
Light 102 is transmitted. The S-polarized light 101 is spatially modulated by the reflective liquid crystal panel 40. Here the liquid crystal panel 4
Reference numeral 0 denotes a TN (Twist Nematic) type liquid crystal, which is an ITO electrode (Indium) coated with an alignment film so as to be oriented at 90 degrees.
Tin oxide (transparent conductive film) is enclosed in glass, and one electrode is made of a metal film in order to obtain a reflection type. If there is no voltage between the ITO electrode and the metal electrode,
The polarization direction of the incident light is rotated by 90 degrees due to the orientation of the TN liquid crystal, so that the S-polarized light becomes P-polarized light and the P-polarized light becomes S-polarized light.

On the other hand, when a voltage is applied between the ITO electrode and the metal electrode, the orientation of the TN liquid crystal is disturbed, and the polarization of the incident light is not rotated. Thus, the S-polarized light 101
The polarization direction does not change in a portion of a pixel to which a voltage is applied, and becomes P-polarized light in a pixel to which a voltage is not applied.
The light reflected by the liquid crystal panel 40 is again incident on the polarization beam splitter 20, passes only the P-polarized light on the polarization separation surface 21, and becomes light 103.

On the other hand, the P-polarized light 102 transmitted from the light source 10 through the polarization splitting surface 21 is incident on a liquid crystal panel 41 having the same structure as that of the liquid crystal panel 40 and, like the liquid crystal panel 40, is applied to a pixel electrode. After changing the polarization direction of the incident light according to the voltage and again entering the polarization beam splitter 20, only the S-polarized light is reflected by the polarization splitting surface 21 and the light 10
It becomes 4.

Light 103 and light 104, each of which has been spatially modulated
Are emitted from the polarization beam splitter 20 in the same direction and overlap. By viewing the lights 103 and 104 with the polarized glasses 200, an image of the liquid crystal panel 41 can be seen with S-polarized glasses, and an image of the liquid crystal panel 40 can be seen with P-polarized glasses. You can see different images from the screen.

As shown in FIG. 2, the light emitted from the polarizing beam splitter 20 is converted into a lens (image magnifying means) 7.
By enlarging the image at 0 and projecting it on the screen 80, the image can be enlarged, and by using the polarizing glasses 200 as described above, different images can be seen according to the polarization direction. Also, a right-eye image and a left-eye image are displayed on the liquid crystal panel 40 and the liquid crystal panel 41, respectively, and a stereoscopic image can be easily viewed by adjusting the polarizing glasses 200 to the corresponding polarization directions.

(Embodiment 2) FIG. 3 is a schematic diagram showing a schematic configuration of an optical modulator according to Embodiment 2 of the present invention. In the first embodiment, the method of easily viewing two images is described. However, if the polarization splitting surface 21 of the polarization beam splitter 20 has poor characteristics, the P-polarized light will be mixed in the S-polarized light 101, so that the liquid crystal panel 40 There is a problem that the contrast of the displayed image deteriorates.

Therefore, in the second embodiment, as shown in FIG. 3, the light 100 emitted from the light source 10 is
Polarizing beam splitter 3 having 1, 22, 23, 24
The S-polarized light 101 is reflected by the polarization splitting surface 21 and the P-polarized light 102 is transmitted. The S-polarized light 101 is
Further, the light is reflected by the polarization splitting surface 22 and enters the reflection type liquid crystal panel 40. The liquid crystal panel 40 changes the polarization direction of incident light for each pixel as in the first embodiment.
The polarized light 101 is spatially modulated by the liquid crystal panel 40, enters the polarization splitting surface 22 again, and transmits only the P-polarized light 103. Further, the P-polarized light 103 passes through the polarization splitting surface 23 and exits from the polarization beam splitter 30.

On the other hand, the P-polarized light 102 separated by the polarization separation surface 21 passes through the polarization separation surface 24 and enters the reflection type liquid crystal panel 41, undergoes spatial modulation, and again enters the modulation separation surface 24. Then, only the S-polarized light is reflected to become light 104. Further, the S-polarized light 104 is reflected by the polarization splitting surface 23, is superimposed on the light 103, and is superposed on the polarization beam splitter 30.
It emits more.

As described above, the S-polarized light 101 and the P-polarized light 102 emitted from the light source 10
Since the light is reflected and transmitted twice at 1, 22, 23 and 24, the separation of S-polarized light and P-polarized light is improved, and the liquid crystal panel 4
The contrast of each of the images 0 and 41 is improved.

In the first and second embodiments, an example of displaying a black-and-white image has been described. Of course, the light source 10 is spectrally separated in advance by a dichroic mirror, a color filter, or the like, and the split light is converted by the light modulation elements 40 and 41. By modulating and combining with a dichroic prism or the like, color display is possible.

As described above, the invention made by the present inventor is:
Although specifically described based on the embodiment, the present invention
It is needless to say that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the scope of the invention.

[0023]

As described above, according to the present invention,
Since the two different polarization components of the incident light are spatially modulated independently of each other, image information by light can be doubled. Thus, the present invention can be applied to optical calculation, stereoscopic display, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a schematic configuration of a light modulation device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing another application example of the first embodiment.

FIG. 3 is a schematic diagram illustrating a schematic configuration of a light modulation device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Light source 20, 30 ... Polarization beam splitter 21, 22, 23, 24 ... Polarization separation surface 40, 41 ... Reflective liquid crystal panel 70 ... Projection lens 80 ... Screen 100 ... Incident light 101 ... S-polarized light 102 ... P-polarized light Of light 103 ... P-polarized light modulated by the light modulation element 40 104 ... S-polarized light modulated by the light modulation element 41 200 ... Polarized glasses

Claims (2)

[Claims] In a light modulator for spatially modulating the brightness of incident light from a light source, a light of a first polarization component of the incident light is reflected and a second light orthogonal to the first polarization is reflected. A polarization separation element having a polarization separation surface through which the light of the polarized light component passes, and a position where the light of the first polarized light component reflected by the polarization separation surface is guided, and the first polarized light component A first reflection-type light modulation element that rotates the polarization direction of the light, and a second polarization component that is located at a position where light of the second polarization component transmitted through the polarization separation surface is guided. A second reflection-type light modulation element for rotating the polarization direction of light, and light modulated by the first reflection-type light modulation element is again incident on the polarization separation surface, and Only the light of the polarization component orthogonal to the light of the component is transmitted, and the second reflection type light modulation element transmits the light. The modulated light is incident on the polarization splitting surface again, and only the light of the polarization component orthogonal to the light of the second polarization component is reflected and the light is modulated by the first reflection type light modulation element. An optical modulator, wherein two different polarized components of the incident light are spatially modulated independently by emitting light in the same direction. 2. An optical modulator for spatially modulating the brightness of incident light from a light source, comprising: a polarization splitting element having first, second, third and fourth polarization splitting surfaces; The first polarized light component is reflected by the first polarized light separating surface, and the reflected first polarized light component is further reflected by the second polarized light separating surface. A first reflection-type light modulation element that rotates a polarization direction of the light of the first polarization component placed at a position where light of the first polarization component is guided;
The light of the second polarization component orthogonal to the light of the first polarization component transmitted through the first polarization separation surface further transmits through the fourth polarization separation surface, and the transmitted second polarization light And a second reflection-type light modulator that rotates the polarization direction of the light of the second polarization component at a position where the light of the component is guided, and the first polarization component of the incident light. Is reflected by the first polarization splitting surface, the light of the second polarization component is transmitted,
The light of the first polarized light component is further reflected by a second polarization splitting surface, is incident on the first reflection type light modulation element and is modulated, and the reflected light is again reflected on the second polarization splitting surface. , And transmits only light of a polarization component orthogonal to the light of the first polarization component, and further transmits and emits through a third polarization separation surface;
On the other hand, the light of the second polarized light component transmitted through the first polarized light separating surface passes through the fourth polarized light separating surface, enters the second reflection type light modulation element, is modulated, and is reflected light. Is the fourth
Of the second polarization component, only the light of the polarization component orthogonal to the light of the second polarization component is reflected, and further, the light is reflected by the third polarization separation surface and is reflected by the first reflection type light modulation element. An optical modulator, wherein two different polarized components of the incident light are spatially modulated independently of each other by emitting the modulated light in the same direction.