Stereoscopic imaging device.

(54) Title: STEREOSCOPIC IMAGE APPARATUS. (54) Title: STEREOSCOPIC IMAGING DEVICE.

(57) Summary

A stereoscopic imaging apparatus is described that is capable of minimizing the loss of optical energy and improving the quality of a stereoscopic image; The stereoscopic imaging apparatus includes a polarization beam splitter to reflect or transmit incident light based on the polarizing components of the light to separate the light in at least three different directions, a reflective member to reflect the light reflected by the polarization beam splitter to a screen, at least a modulator to modulate the light reflected by the reflector member and the light transmitted through the polarization beam splitter, and a refraction member disposed in a forward direction of light to be incident on the polarization beam splitter to refract light to be incident on the polarization beam splitter.

(57) Abstract

The purpose of the present invention is to provide a stereoscopic imaging device capable of minimizing optical energy loss and improving image quality. To this end, the present invention provides a stereoscopic imaging device comprising: a polarizing beam splitter for splitting incident light in at least three different directions by reflecting or passing through the incident light according to polarization components; a reflection member for reflecting the light reflected from the polarizing beam splitter towards a screen direction; at least one modulator for modulating the light reflected from the reflection member and the light which has passed through the polarizing beam splitter; and a refraction member for refracting the light to be incident to the polarizing beam splitter by being arranged in the traveling direction of the light to be incident to the polarizing beam splitter.

I KNOW

SECHTMÍA I heard ICCI5MW *

<img file="MX340570B_D0001.tif" />

Mexican Institute of Industrial Property

<img file="MX340570B_D0002.tif" />

PATENT TITLE NO. 340570

Owner (s): MASTERIMAGE 3D ASIA, LLC.

Address: Gasan-dong, BYC Highcity Building A 22F, 131 Gasan DigitaH -ro, 153-803,

Geumcheon-gu, Seoul, REPUBLIC OF KOREA

Name: STEREOSCOPIC IMAGING DEVICE

Classification: lnt.CI.8: G02B27 / 26; G03B21 / 28; G03B35 / 26; H04N13 / 04

Inventor (s): CHUL WOO LEE; SUNG HO CHO; BYUNG GUL LIM

REQUEST

Number: International filing date!

MX / a / 2014/011876 March 26, 2014

PRIORITY

Country: Date: Number:

KR April 2, 2013 10-2013-0035805

Validity: Twenty years

Expiration Date: March 26, 2034

The reference patent is granted based on articles 1, 2 fraction V, 6 fraction III, and 59 of the Industrial Property Law.

: ' ........ _

In accordance with article 23 of the Industrial Property Law, this patent has a validity of twenty years, which cannot be extended, counted from the date of filing of the international application and will be subject to the payment of the tartf »to keep the rights in force. .

Whoever subscribes to this title does so based on the provisions of articles 6 · fraoeiones III and 7 ° bis 2 of the Industrial Property Law (Mario Oficial de la Federación (DOF) 06/27/1991, reforrtWiaátíS / Oe / ie * », 10/25/1996, 12/26/1 ®7, 05/17/1999, 01/26/2004, 06/16/2005, 01/25/2996, 05/06/2009 / 06.06 / 01/2010, 06/15/2010, 06/28 0010. 27Λ1 / 2012 and 04/09/2012); articles jf ', 3rd section V a), 4th and 12th sections I and III of the Regulations of the MaxKMno Institute of Industrial Property (DOF 12/14 / 19®, amended on 07/01/2002, 07/15/2004, 07/28/2004 and 09/07/2007), articles 1, 3, 4, 5 * section V subsection a ), 16 sections I and III and 30 of the Organic Statute and Section 5 a) of the Agreement that delegates powers to the Deputy Directors General, Coordinator, Divisional Directors, Head of the Regional Offices, Divisional Deputy Directors, Departmental Coordinators and other subordinates of the Institute Mexican of Industrial Property. (DOF 12/15/1999, amended on 02/04/2000, 07/29/2004, 08/04/2004 and 09/13/2007).

<img file="MX340570B_D0003.tif" />

Issue Date: July 13, 2016

THE DIVISIONAL DIRECTOR OF PATENTS

<img file="MX340570B_D0004.tif" />

NAHANNY CANAL REYES

Arenal No, 550. Step 1.

: oi. Pueblo Sania María Tepepan,

Xochimiico. CP. 16020 Mexico City

Tal (55) 53 34 07 00 wwtrcpi gob tnx

<img file="MX340570B_D0005.tif" />

MX / 2016/54901

<img file="MX340570B_D0006.tif" />

7105=10

<img file="MX340570B_D0007.tif" />

¹ IMPI

MEXICAN INSTITUTE ¡X THE PROPERTY

INDUSTRIAL

STEREOSCOPIC IMAGING DEVICE

<img file="MX340570B_D0008.tif" />

FIELD OF THE INVENTION

The present invention relates to a stereoscopic imaging apparatus that is capable of transmitting some light consisting of an incident image signal and reflecting the rest of the light to separate the light and to condense the separated light onto a screen to increase brightness.

BACKGROUND OF THE INVENTION

Figure 1 is a view showing a conventional polarization beam splitter.

When a light that has a P-polarization and an S15 polarization in a mixed state is Incident on a polarization beam splitter (PBS) 1, the P-polarization is transmitted through the beam splitter Polarization 1 and S-polarization is reflected by the polarization beam splitter 1.

The reflected S-polarization and the transmitted P-polarization are directed in the same direction by diamond-shaped prisms 2 and 3.

For example, P-polarization is transmitted through the prism and then switched to S-polarization by means of a half-wave plate (retarder) 4.

IMPI

MEXICAN INSTITUTE Of LA rROHEBAD INDUSTRIAL

<img file="MX340570B_D0009.tif" />

As a result, the light having P-polarization and Spolarization in the mixed state is switched to the same polarization, for example S-polarization, by means of the polarization beam splitter. That is, the light that has the P-polarization and the S-polarization in the mixed state has the same direction.

A principle of operation of a stereoscopic imaging apparatus using the conventional polarization beamsplitter is as follows. US Patent No. 7,857,455 is mentioned.

As shown in Figure 2, light emitted from an image surface 5 that generates an image on a projector passes through a projection lens 6 and is then separated into two beams by means of a polarization beam splitter 7 .

That is, light having an S-polarization state and a P-polarization state is reflected by the polarization beam splitter 7 or transmitted through the polarization beam splitter 7.

The transmitted or reflected P-polarization component is switched to S-polarization as it passes through the half-wave retarder 8. The S-polarization is concentrated on a projection screen by means of reflector members 9 and 10, a polarizer 11 , and a modulator 12.

Modulator 12 can change a bias state / direction, for example, according to an electrical signal.

On the other hand, the S-polarization component reflected by the

MEXICAN INSTITUTE OF LA moniDAD

WPUSTUIAL

<img file="MX340570B_D0010.tif" />

Polarization beam splitter 7 reaches the screen of-fw-eyecrinn pnr. rciadin. of a reflector member 13 in a state where the S-polarization is maintained in the same direction.

Accordingly, the light, having mixed polarization states / directions, emitted from the image surface 5 is switched to a single S-polarization.

However, the stereoscopic imaging apparatus using the conventional polarization beamsplitter has the following problems.

In general, a vertical angle of departure of the projector is approximately 15 degrees. A case where the exit angle is 15 degrees is shown in Figure 3. A polarizer and modulator are omitted from Figure 3 for simplicity.

The distance between a polarization beam splitter and a reflector member 16 and the distance between the polarization beam splitter and another reflector member 16 are assumed to be h1 and h2, respectively, and the distances between the respective reflector member 16 and 17 and a screen 18 are L1 and L2, respectively.

In this case, an angle Θ1 between the light reflected by the reflector member 16 and an optical axis of the light emitted from the projector is TAN20 1 (h1 / L1) and an angle Θ2 between the light reflected by the reflector member 17 and the Optical axis of the light emitted from the projector is TAN-1 (h2 / L2).

Reference number 161 indicates the light reflected by the reflector member 16 and reference number 171 indicates the light reflected by

<img file="MX340570B_D0011.tif" />

the reflector member 17. ——_

The distortion of an image on the screen 18 caused by the angles Θ1 and 02 is as follows. Figure 4 is an elongated view showing part (A) of Figure 3.

With reference to Figure 4, reference number 161 indicates the light reflected by the reflecting member 16 and reference number 171 indicates the light reflected by the reflecting member 17.

Furthermore, reference number 162 indicates an image-forming surface of the light reflected by the reflecting member 16 and reference number 172 indicates an image-forming surface of the light reflected by the reflecting member 17.

Assuming that the height of the screen 18 is H, a height difference d1 between the image-forming surface of the light reflected by the reflecting member 16 and the image on the screen 18 and a height difference d2 between the surface which forms the image of the light reflected by the reflecting member 17 and the image on the screen 18 are expressed as follows.

d1 = Η ΤΑΝ (Θ1), d2 = Η ΤΑΝ (Θ2)

Consequently, the beams reflected by the reflector members 16 and 17 form images on the image-forming surface with a distance difference Δ = (Η / 2) {ΤΑΝ (Θ1) + TAN (02)}.

In a case where h1 = h2 = 340 mm, L1 = L2 = 15000 mm, and H = 8500 mm, Θ1 = 62 = 1.3 degrees and, therefore, Δ = 193 mm.

IMPI

<img file="MX340570B_D0012.tif" />

This means that the light reflected by the reflecting member 16 and the light reflected by the reflecting member 17 deviate from each other on the image-forming surface by a maximum of 193 mm. In general, the beam size is several mm. As the distance from the center of the screen 18 increases, therefore, the image becomes less visible, leading to limitations in use.

BRIEF DESCRIPTION OF THE INVENTION

Technical problem

An object of the present invention contemplates solving the problem encountered in a stereoscopic imaging apparatus that is capable of improving the quality of a stereoscopic image and minimizing the loss of optical energy.

Technical Solution

In accordance with one aspect of the present invention, the above objectives and other objectives can be achieved by providing a stereoscopic imaging apparatus including a polarization beam splitter to reflect or transmit incident light based on the states of light polarization to separate light in at least three different directions, a reflector member to reflect light reflected by the polarization beam splitter on the screen, at least one modulator

<img file="MX340570B_D0013.tif" />

<img file="MX340570B_D0014.tif" />

to modulate the light reflected by the reflector member y-ia Iht transmitted through the polarization beam splitter, and a refraction member arranged in a forward direction of light to be incident on the polarization beam splitter and adapt to refract the light to be incident on the polarization beam splitter.

Advantageous Effects

According to the present invention, it is possible to overcome the deterioration in image quality and the impossibility in realizing a large screen due to the mismatch of the two beams on the screen, which is caused in the conventional stereoscopic imaging apparatus.

That is, one light path is divided into a transmitted light path and two reflected light paths, and the split beams are combined on the screen, thereby greatly reducing an image height error.

In addition, two polarization beam splitters are provided connected to each other while bending so that some of the incident light is reflected by and transmitted through one of the polarization beam splitters and the rest of the incident light is reflected by and transmitted through the other polarization beam splitter. Consequently, the beams are divided along the respective paths, thereby achieving an accurate stereoscopic image.

Meanwhile, the refraction member is placed in the part

<img file="MX340570B_D0015.tif" />

IMPI iHJTrruTo mexican tft THE INDUSTRIAL PROPERTY front of the polarization beam splitter to avoid quo4a-lug gea nriripntn, in the area of ​​light reduction formed in the polarization beam splitter, thus avoiding the loss of optical energy.

That is, the light incident at the center of the refraction member is refracted and the refracted beams are emitted as they are uniformly separated from each other and are incident on the polarization beam splitter. Since the light reduction area is located between the refracted beams, it is possible to prevent light emitted from the refraction member from entering the light reduction area.

Also, an additional member can be placed in the transmitted light path to increase a divergence angle of the transmitted light or an additional member can be placed in the reflected light path to decrease a divergence angle of the reflected light, thus reducing a height difference between the transmitted light and the reflected light and thus considerably reducing image error.

Furthermore, the polarizing beam splitter includes two interconnected light transmitting members and a polarizing beam dividing film placed between the light transmitting members. Accordingly, it is possible to remove the astigmatism from the light reflected by the polarization beam splitter and transmitted through the polarization beam splitter.

Meanwhile, it is possible to reduce the distance between the divider of the

<img file="MX340570B_D0016.tif" />

<img file="MX340570B_D0017.tif" />

polarization beam and reflector member compared to conventional stereoscopic imaging apparatus, thereby reducing the size of the stereoscopic imaging apparatus and thereby achieving a compact structure of the stereoscopic imaging apparatus.

Those skilled in the art will appreciate that the effects that could be achieved with the present invention are not limited to those that have been particularly described herein before and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a view showing a conventional bias beam splitting method to obtain a single bias;

Figure 2 is a view showing the structure of a conventional stereoscopic imaging apparatus;

Figures 3 and 4 are side sectional views illustrating the problems of conventional stereoscopic imaging apparatus;

Figure 5 is a view showing the basic structure of a stereoscopic imaging apparatus in accordance with the present invention;

FIG. 6 is a view showing the light paths in polarization beam splitters of the stereoscopic imaging apparatus.

<img file="MX340570B_D0018.tif" />

<img file="MX340570B_D0019.tif" />

in accordance with the present invention; _

FIG. 7 is a view showing a light path in a case where the refractive members are added to the stereoscopic imaging apparatus according to the present invention;

Figure 8 is a view showing another form of the polarization beam splitter of the stereoscopic imaging apparatus according to the present invention;

Figure 9 is a view showing the structure of the stereoscopic imaging apparatus according to the present invention in a case where the refractive member is added to the stereoscopic imaging apparatus;

FIG. 10 is a view showing the structure of the stereoscopic imaging apparatus according to the present invention in a case where a plurality of the different modulators are placed in the stereoscopic imaging apparatus;

Figure 11 is a view showing the structure of the stereoscopic imaging apparatus according to the present invention in a case where a half-wave retarder is placed in the stereoscopic imaging apparatus of Figure 10;

FIG. 12 is a view showing a light path in the stereoscopic imaging apparatus according to the present invention;

Figure 13 is a side view showing a structure

<img file="MX340570B_D0020.tif" />

to correct a path of light transmitted in qp n-argtn Ha stemanently according to the present invention; and

Figures 14 to 17 are side views showing the structures for correcting a reflected light path in the stereoscopic imaging apparatus according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. ·

Figure 5 is a view showing the basic structure of a stereoscopic imaging apparatus in accordance with the present invention.

Hereinafter, an image signal will be referred to as 'light' for convenience, and the term 'light' therefore implies the meaning of the 'image signal'.

As shown in Figure 5, light, which has been emitted from an image surface 19 and passed through a projection lens 20, is Incident at Polarization Beam Splitters (PBS) 21 and 22 on a state where the light has a P-polarization and an S20 polarization in a mixed state.

For convenience, the polarization beam splitter denoted by reference number 21 will be referred to as a first polarization beam splitter and the polarization beam splitter denoted

INSTITUTO MtXKAHO pr la rwriUMP v% ^ ¿¡¡/ NÜWRfTÜAL by reference number 22 will be mentioned as a second polarization beam splitter.

The polarization beam splitters 21 and 22 cannot be formed into a single flat plate shape. The polarization beam dividers 21 and 22 can be formed such that a section defined by the polarization beam dividers 21 and 22 is bent .

The center of the polarization beam splitters 21 and 22 can be located on an optical axis of incident light.

The first polarization beam splitter 21 and the second polarization beam splitter 22 can be connected to each other. The first polarization beam splitter 21 and the second polarization beam splitter 22 can be positioned such that the first polarization beam splitter 21 and the second polarization beam splitter 22 face each other in different directions.

That is, the first polarization beam splitter 21 and the second polarization beam splitter 22 can each be formed into a plate shape such that the plate shape of the first polarization beam splitter 21 and the plate shape of the second polarization beam splitter 22 tilt in different directions.

In the aforementioned structure, half of the incident light in the polarization beam splitters 21 and 22 may be incident in the first polarization beam splitter 21 and the other half of the incident light in the polarization beam splitters 21 and 22 can be incident in the

IMPIfts

MEXICAN INSTITUTE

OF PROPERTY OR »

INDUSTRIAL * = second polarization beam splitter 22.

The polarization beam splitters 21 and 22 transmit a specific polarization component (a P-polarization component) and reflect another polarization component (an S-polarization component) in a direction different from a direction in which light is transmits to separate light in a plurality of directions.

Accordingly, the P-polarization component of incident light in the first polarization beam splitter 21 is transmitted and then advanced to a screen.

On the other hand, the S-polarization component of incident light in the first polarization beam splitter 21 is reflected and then advances in a first direction (in an upward direction in Figure

5).

Furthermore, the P-polarization component of the incident light in the second polarization beam splitter 22 is transmitted and then advanced to the screen.

On the other hand, the S-polarization component of incident light in the second polarization beam splitter 22 is reflected and then advances in a second direction (in a downward direction in Figure

5).

That is, some of the incident light is reflected and the rest of the incident light is transmitted.

The reflected light is also separated. Some of the reflected light is

<img file="MX340570B_D0021.tif" />

INSTITUTO MEXICANO DK LA PROPIEDAD INDUSTRIAL reflects by means of the first polarization beam splitter 21 and the rest of the reflected light is reflected by the second polarization beam splitter

22.

In addition, the transmitted light is also separated. Some of the transmitted light 5 is transmitted through the first polarization beam splitter 21 and the remainder of the transmitted light is transmitted through the second polarization beam splitter 22.

Above the first polarization beam splitter 21 and the second polarization beam splitter 22 are respectively provided reflector members 23 and 24, like mirrors, which separate from the first polarization beam splitter 21 and the second polarization beam splitter 22, respectively.

Representative examples of reflector members 23 and 24 can be mirrors. However, the present invention is not limited to this. The reflecting members 23 and 24 can be made up of all the elements that are capable of representing a function to reflect light.

The reflective member denoted by reference number 23 will be mentioned as a first reflective member and the reflective member denoted by reference number 24 will be mentioned as a second reflective member.

The light reflected by the first polarization beam splitter 21 and the first reflector member 23 and the light reflected by the second polarization beam splitter 22 and the second reflector member 24 each have the

<img file="MX340570B_D0022.tif" />

of the polarizing beam 22 and the second reflector member 24 advance to the screen and then combine with each other on the screen.

Beams reflected and then moving in both directions can be provided to divide the incident light section into two equal parts. Beams reflected and then moving in both directions have the same polarization component.

Meanwhile, the beams transmitted through the first polarization beam splitter 21 and the second polarization beam splitter 22 advance to the screen along an optical axis while having the P-polarization component.

In the aforementioned structure, one half of the light that has passed through the projection lens 20 can reach the first polarization beam splitter 21 and can then be reflected by the first polarization beam splitter 21 or can be transmitted through the first beam splitter polarization beam 21 and the other half of the light transmitted through the projection lens 20 can reach the second polarization beam splitter 22 and can then be reflected by the second polarization beam splitter 22 or it can be transmitted through the second polarization beam splitter 22.

In a case where images that are the same size are projected on the screen, therefore, it is possible to reduce

<img file="MX340570B_D0023.tif" />

<img file="MX340570B_D0024.tif" />

Considerably the distance between the polarization beam splitters 21 and 22 and the reflector members 23 and 24 compared to conventional stereoscopic imaging apparatus, meaning that it is possible to reduce the size of the stereoscopic imaging apparatus.

In a case where the distance between the polarization beam dividers 21 and 22 and the reflector members 23 and 24 of the stereoscopic imaging apparatus according to the present invention is equal to the distance between the polarization beam dividers and the members reflectors of the conventional stereoscopic imaging apparatus, on the other hand, the size of the image projected on the screen in the stereoscopic imaging apparatus according to the present invention can be considerably larger than the size of the image projected on the screen in the conventional stereoscopic imaging apparatus based on the aforementioned structure.

The reason why the size of the stereoscopic imaging apparatus can be reduced as described above, will be described hereinafter in detail.

Figure 6 shows the paths of light transmitted through the first polarization beam splitter 21 and the second polarization beam splitter 22.

As shown in Figure 6, light, having a diameter D, incident on the first polarization beam splitter 21 and the second polarization beam splitter 22 is refracted when the light is transmitted to

<img file="MX340570B_D0025.tif" />

IM F

INSTITUTO MEXICANO Ot IA INDUSTRIAL PROPERTY through the first polarization beam splitter 21 and the second polarization beam splitter 22.

In this case, most of the transmitted light is transmitted through the first polarization beam splitter 21 and the second polarization beam splitter 22 and moves behind the first polarization beam splitter 21 and the second beam splitter However, the central light (the light having a diameter d) enters the first polarization beam splitter 21 and the second polarization beam splitter 22 and then gathers at one point.

Consequently, the light of diameter d does not reach the screen but is extinguished.

That is, the light is incident on a defined bent portion between the first polarization beam splitter 21 and the second polarization beam splitter 22 and is then concentrated at one point to form a brightness reduction area (DA, by its acronym in English).

Some of the light that has passed through the polarization beam splitters 21 and 22 passes through the brightness reduction area (DA). At this time, the energy of light is reduced. Consequently, the light intensity on the screen is reduced with the result that the entire area of ​​the screen darkens relatively.

Therefore, it is necessary to provide a correction method that is capable of solving the aforementioned problem.

Figure 7 shows a structure related to said

<img file="MX340570B_D0026.tif" />

correction method.

As shown in Figure 7, refractive members 25 and 26 are provided having a refractive index and thickness similar to that of the first polarization beam splitter 21 and the second polarization beam splitter 22.

Refractive members 25 and 26 can each be formed into a plate shape. However, the present invention is not limited to this.

The refraction member 25 corresponding to the first polarization beam splitter 10 will be mentioned as a first refraction member and the refraction member 26 corresponding to the second polarization beam splitter 22 will be mentioned as a second refraction member.

The shape of the first refraction member 25 is similar to that of the first polarization beam splitter 21 and the shape of the second refraction member 26 is similar to that of the second polarization beam splitter 22.

That is, the first refractive member 25 is located above the optical axis and the second refractive member 26 is located below the optical axis. The first refraction member 25 and the second refraction member 26 are connected to each other. A bent portion is formed in the center of the first refraction member 25 and the second refraction member 26. I

The first member of refraction 25 and the second member of

<img file="MX340570B_D0027.tif" />

MLXICAN INSTITUTE t * LA TODHÍDAU INDUSTRIAL refraction 26 can face the first polarization beam splitter 21 and the second polarization beam splitter 22, respectively, in a symmetrical mode.

The first refraction member 25 and the second refraction member 26 tilt in different directions in a state where the first refraction member 25 and the second refraction member 26 are connected to each other.

In the aforementioned structure, the beam paths are formed as follows.

The beams incident on the refraction members 25 and 26 are refracted with the result that the beam paths are changed. The beams move toward the polarization beam splitters 21 and 22.

At this time, an empty area (EA), through which the beams do not pass, forms between the center of the refraction members 25 and 26 and the polarization beam splitters 21 and 22. since the center of the refraction members 25 and 26 are bent.

The incident path of incident light in the light reduction area (DA) is shown in Figure 6 corresponding to the empty area (EA) shown in Figure 7. Since the light does not advance further into the empty area (EA) ) Due to the refraction of light by means of refraction members 25 and 26, light is no longer incident in the area of ​​reduced light (DA). Therefore, it is possible to prevent the loss of light caused by the extinction of light.

'J &amp; F' ·· χΛ

IMPI

IWTTTÍTTCí MEXICANO ¡Rí ιλ? Ϊ «οη®» Λΐ&gt;

WBWOJfíAL

Figure 8 is a view showing a method of reducing the astigmatism that can occur in the polarization beam splitter.

The first polarization beam splitter 21, the first refractive member 25, and the first reflector member 23 are shown in Figure

8. However, the descriptions of the first polarization beam splitter

21, the first refraction member 25, and the first reflector member 23 are applied equally to the second polarization beam splitter 22, the second refraction member 26, and the second reflector member 24.

When light that has passed through the first refractive member 25 reaches the first polarization beam splitter 21, a polarization is transmitted through the first polarization beam splitter 21 and an S-polarization is reflected across the entire surface of the first polarizing beam splitter 21 and then advances to the first reflector member 23.

At this time, the length of the transmitted light path is increased by a thickness T of the first polarization beam splitter 21 compared to the length of the reflected light path. This is because the reflected light does not move in the first polarization beam splitter 21 and is then reflected but reflected by the surface of the first polarization beam splitter 21, while the transmitted light passes through the first beam splitter polarization 21.

In this case, light astigmatism can occur due to the difference in path length between reflected light and light

<img file="MX340570B_D0028.tif" />

transmitted.

IMPI

INSTT7VTO MEXICANO Dt IA rUCMEOAP industrial

To correct such astigmatism, it is necessary to equalize the length of the light reflected by the first polarization beam splitter 21 and the length of the light transmitted through the first polarization beam splitter 21.

Accordingly, the first polarization beam splitter 21 is formed by combining two light transmitting members 211 and 212 having the same thickness. A polarization beam splitting film 213 is placed between the light transmitting members 211 and 212.

Assuming that the thickness of the first polarization beam splitter 21 is T and the thickness of each of the light transmitting members 211 and 212 is t, T = 2t (the thickness of the polarization beam splitting film is ignored. ).

For convenience, it is assumed that the thickness of the light transmitting member 211 located on the front side is t1 and the thickness of the light transmitting member 212 located on the rear side is t2.

The P-polarization of the incident light passes through the front side light transmitting member 211, the polarizing beam splitting film 213, and the rear side light transmitting member 212.

At this time, the length of the transmitted light path in the first polarization beam splitter 21 is t1 + t2.

On the other hand, the S-polarization of the incident light passes through the front-side light transmitting member 211, reaching the film of

<img file="MX340570B_D0029.tif" />

INSTTTUTO MIXICANO PE IA FROPIEDAD

INDUSTRIAL

<img file="MX340570B_D0030.tif" />

polarization beam splitting 213 and is reflected by polarization beam splitting film 213 and then passes through the front side light transmitting member 211.

At this time, the length of the reflected light path in the first polarization beam splitter 21 is t1 + t1. Since t1 = t2 as described above, the length of the reflected light path and the length of the transmitted light path are equal. Therefore, it is possible to prevent the occurrence of astigmatism.

The incident angle, transmission angle, and reflection angle of reflected light and transmitted light are not exactly 0. Since the first polarization beam splitter 21 and the light transmission members 211 and 212 that make up the First polarization beam splitter 21 are very thin, however, you can ignore the change in the length of the paths due to the angles.

FIG. 9 is a view showing a basic construction of a polarization beam splitting method according to the present invention.

The section of the reflected S-polarization is divided into two equal parts. As a result, the distance between an optical axis of the projection lens 20 and the first reflector member 23 and the distance between the optical axis of the projection lens 20 and the second reflector member 24 are halved. For example, the distance between an optical axis of the projection lens 20 and the first reflector member 23 and the distance between the axis

IMPI

IHiin VTO MKICANV Of the industrial wopudac

<img file="MX340570B_D0031.tif" />

of the projection lens 20 and the second reflector member 24 may be 75mm.

The aforementioned distance in the polarization beam division method according to the present invention is equivalent to 1/4 the distance, which is 340 mm, in the conventional polarization beam division method shown in Figure 2 , which means that the angle errors Θ1 and 02 with the image-forming surface on screen 18 shown in Figure 2 are reduced to about 1/4 when using the conventional method.

Next, a description will be given of a case where the structure shown in Figure 9 is applied to a stereoscopic imaging apparatus having improved brightness.

Referring to Figure 10, the reflected S-polarization by the first reflector member 23 and the second reflector member 24 is modulated by a first modulator 27a and a third modulator 27c, respectively.

On the other hand, the P-polarization transmitted through the first polarization beam splitter 21 and the second polarization beam splitter 22 is modulated by a second modulator 27b.

The first modulator 27a and the third modulator 27c are provided such that the first modulator 27a and the third modulator 27c have the same phase delay function. The second modulator 27b is provided such that the second modulator 27b has a mean wavelength phase difference of the first and third

IMPI

MEXICAN INSTITUTE Γ&gt; € LA FRCrttDAO INnuSTMlAL

<img file="MX340570B_D0032.tif" />

modulators 27a and 27c.

The first and third modulators 27a and 27c convert an S-polarization state according to an electrical signal. For example, the first and third modulators 27a and 27c convert the Spolarization state from a linear polarization state to a circular polarization state.

Meanwhile, the P-polarization transmitted through the polarization beam splitters 21 and 22 is modulated into an S-polarization as it passes through the second modulator 27b. At the same time, the P-polarization state is modulated from a linear polarization state to a circular polarization state.

The first and third modulators 27a and 27c convert an S-polarization state from a linear polarization state to a circular polarization state while maintaining S-polarization. Accordingly, the first and third modulators 27a and 27c perform a phase delay function of 1/4 of the wavelength.

On the other hand, the second modulator 27b converts the P-polarization state from a linear polarization state to a circular polarization state (performs a phase delay function of 1/4 wavelength) while converting the P -polarization in an S-polarization (performing a phase delay function of 1/2 the wavelength). Accordingly, the second modulator 27b performs a total of 3/4 wavelength phase delay function.

IMPI

INSTITUTO MUBCANO DF LA PROnWAD INDUSTRIAL

<img file="MX340570B_D0033.tif" />

In the embodiment shown in Figure 10, the first to third modulators 27a to 27c can be separated from each other or separated from each other.

This is because, in a state where the first modulator 5 27a, the second modulator 27b, and the third modulator 27c are successively placed, the phase delay characteristics generated in the first and third modulators 27a and 27c are different from those of the phase delay generated in the second modulator 27b.

FIG. 11 is a view showing another embodiment having another element added to the embodiment shown in FIG. 10.

Figure 11 shows a structure where a mid-wave retarder 28 for converting the transmitted P-polarization through the first polarization beam splitter 21 and the second polarization beam splitter 22 into an S-polarization is added to the structure shown in Figure 10.

That is, the medium wave retarder 28 is placed at the rear of the first and second polarization beam splitters 21 and 22 and is placed at the front of the second modulator 27b.

In other words, the medium wave retarder 28 is positioned 20 between the first and second polarization beam splitters 21 and 22 and the second modulator 27b.

In the aforementioned structure, the light that has passed through the medium wave retarder 28 and the light reflected by the first and

IMPI

MEXICAN INSTITUTE OF PROPERTY

INDUSTRIAL

<img file="MX340570B_D0034.tif" />

second reflector members 23 and 24 have characteristics of the same polarization, ie the S-polarization.

Accordingly, it is possible to convert polarizations from a linear polarization state to a circular polarization state using a large single modulator in place of the first, second, and third modulators 27a, 27b, and 27c. The large single modulator can retard the incident light phase by 1/4 the wavelength to convert light from a linear polarization state to a circular polarization state.

Meanwhile, although not shown, the medium wave retarder 28 can be positioned between the first reflector member 23 and the first modulator 27a and / or between the second reflector member 24 and the third modulator 27c.

In a case where both a polarization moving along a reflection path and a polarization moving along a transmission path reach the screen, the polarizations must be changed to a single polarization (a Ppolarization or an S-polarization).

In a case where the mid-wave retarder 28 is placed in the transmission path, therefore, the polarizations reaching the screen can form an image on the screen in a state of Spolarization.

On the other hand, in a case where the medium wave retarder

IMPI

INSTITUTO MEXICANO DF THE INDUSTRIAL PROPERTY is placed in the path of reflection, the polarizations that reach the screen can form an Image on the screen in a state of Ppolarlzaclón.

In accordance with the present invention as described above, the number of beam paths projected on the screen in an overlapping mode is 3.

That is, the beam paths include a first path along which light is transmitted through the first polarization beam splitter 21 and the second polarization beam splitter 22 and then projected onto the screen, a second path along which light is reflected by means of the first polarization beam splitter 21 and the first reflector member 23 and then projected onto the screen, and a third path along which light is reflected by means of the second polarization beam splitter 22 and the second reflector member

24 and then it is projected on the screen.

Next, a description will be given of a method of overcoming a difference between the image-forming surface of the light reflected by the first polarization beam splitter 21 and the second polarization beam splitter 22 and the image-forming surface. of light transmitted through the first polarization beam splitter 21 and the second polarization beam splitter 22 to provide Images that are the same size on the screen.

Figure 12 shows a difference in height Δ between the

<img file="MX340570B_D0035.tif" />

MEXICAN INSTITUTE I heard THE INDUJTWAL PROPERTY

<img file="MX340570B_D0036.tif" />

Surfaces that form the Image of light mainly reflect it pnr..ei first polarization beam splitter 21 and the second polarization beam splitter 22 and secondary reflected by the first reflective member 23 and the second reflective member 24 and the surfaces forming the image of light transmitted through the first polarization beam splitter 21 and the second polarization beam splitter 22.

Reference number 219 indicates the image-forming surface of light transmitted through the first polarization beam splitter 21 and reference number 229 indicates the image-forming surface of light transmitted through the second beam splitter polarization 22.

Reference number 239 indicates the image-forming surface of the light reflected by the first reflecting member 23, and reference number 249 indicates the image-forming surface of the light reflected by the second reflecting member 24.

The imaging surfaces 239 and 249 of the beams moving along the reflection paths are located at the front of the imaging surfaces 219 and 229 of the beams moving along the paths. transmission paths. The height difference Δ is generated due to this difference in position.

The height difference Δ can be reduced using the following four methods.

A first method is to increase a divergence angle of

ΙΜΡΙ

MEXICAN INSTITUTE Say THE PROPERTY

INDUSTRIAL

<img file="MX340570B_D0037.tif" />

light transmitted through the first polarization beam splitter 21 v the second polarization beam splitter 22 using a lens 29 as shown in Figure 13.

The lens may have concave lens characteristics to increase the angle of light divergence.

In this method, a light path 299 after correction by lens 29 is separated more than a light path 298 before correction by lens 29 is performed with the result that the size of the image is increased. an image on the screen.

Referring to Figure 13, a transmission path indicated by a solid line indicates path 298 before correction is made by lens 29 and a transmission path indicated by a dotted line indicates path 299 after correction is performed by means of lens 29.

It can be seen that the path indicated by the dotted line is separated more than the path indicated by the solid line.

As a result, the size of an image formed on the screen by the beams moving along the transmission paths becomes equal to the size of an image formed on the screen by the beams moving along the paths. of reflection, whereby the height difference Δ previously described can be eliminated.

At this time, it should be noted that lens 29 must be positioned between the two reflection paths so that the beams that

<img file="MX340570B_D0038.tif" />

they move along the reflection paths do not interfere with the lens 29.

A second method of eliminating the height difference Δ is to arrange the lenses 30 and 31 to reduce the beam divergence angles in the reflection paths as shown in Figure 14.

Lenses 30 and 31 can have convex lens characteristics to decrease beam divergence angles to some extent.

Lenses 30 and 31 can be positioned adjacent the first reflector member 23 and the second reflector member 24 in a state where the lenses 30 and 31 are located on paths along which the beams reflected by the first member advance. reflector 23 and the second reflector member 24.

In this method, the light paths 309 and 319 after the correction is made by means of the lenses 30 and 31 are separated less than the light paths 308 and 318 before the correction is made by means of the lenses 30 and 31 with the result that the size of an image on the screen decreases.

Referring to Figure 14, the reflection paths 20 indicated by the solid lines indicate the paths 308 and 318 before correction is made by the lenses 30 and 31 and the reflection paths indicated by the dotted lines indicate the trajectories 309 and

319 after correction is made by means of lenses 30 and 31.

IMPI

MEXICAN INSTITUTE OF INDUSTRIAL PROPERTY

It can be seen that the trajectories indicated by the lines

<img file="MX340570B_D0039.tif" />

Dotted lines are less separated than the paths indicated by the solid lines.

As a result, the size of an image formed on the screen by beams moving along the reflection paths becomes equal to the size of an image formed on the screen by beams moving along the paths. transmission, so the height difference Δ described above can be eliminated.

At this time, it should be noted that lenses 30 and 31 must deviate from transmission paths so that beams moving along transmission paths do not interfere with lenses 31.

On the other hand, it is possible to use a method to correct beam paths using plates or prisms 32 and 33 to reduce beam divergence angles as shown in Figure 15 instead of using the correction method using lenses. 30 and 31 as shown in Figure 14.

This is a third method to eliminate the height difference Δ. The plates or prisms 32 and 33 may have convex lens characteristics to decrease beam divergence angles to some extent.

The plates or prisms 32 and 33 can be placed adjacent to the first reflector member 23 and the second reflector member 24 in a state

ΙΜΡΪ

INSTITUTO MEXICANO 'fk-fcsffiSS DE LA «OPIÍDAD &lt;*« a «22 £ industrial it in which the plates or prisms 32 and 33 are located on paths along which the beams reflected by the first reflector member 23 advance and the second reflector member 24.

In this method, light paths 329 and 339 after correction is made by means of plates or prisms 32 and 33 are separated less than light paths 328 and 338 before correction is made by means of plates or prisms 32 and 33 with the result that the size of an image on the screen decreases.

Referring to Figure 15, the reflection paths indicated by solid lines indicate paths 328 and 338 before correction is made by plates or prisms 32 and 33, and the reflection paths indicated by dotted lines indicate paths 329 and 339 after correction is made by plates or prisms 32 and 33.

It can be seen that the paths indicated by the dotted lines are less separated than the paths indicated by the solid lines.

As a result, the size of an image formed on the screen by beams moving along the reflection paths becomes equal to the size of an image formed on the screen by beams moving along the paths. transmission, so the height difference Δ described above can be eliminated.

At this time, it should be noted that the plates or prisms 32 and

IMPI Mexican Institute of LA RRoriEDAD

IMsTRIAt _ must deviate from transmission paths so that

<img file="MX340570B_D0040.tif" />

Beams moving along transmission paths do not interfere with plates or prisms 32 and 33.

A fourth method to eliminate height difference Δ is to use reflector member prism assemblies (mirror prism assemblies) 34 and 35 as shown in Figure 16.

Reflective member prism assemblies 34 and 35 are configured such that lenses 30 and 31 or plates or prisms 32 and 33 shown in Figures 14 or 15 are easily and conveniently detached from the reflective members.

Reflective member prism assemblies 34 and 35 reduce beam divergence angles.

The reflector member prism assemblies 34 and 35 can be located on the paths along which the reflected beams advance by the first polarization beam splitter 21 and the second polarization beam splitter 22.

In this method, light paths 349 and 359 after correction is performed by means of reflector member prism assemblies 34 and 35 are spaced less than light paths 348 and 358 before correction is performed by means of the reflector member prism assemblies 34 and 35 with the result that the size of an image on the screen decreases.

Referring to Figure 16, the reflection paths

IMPI 'Νίτπυτο MUCAMO I heard the nmmoAb INDWnWAL

<img file="MX340570B_D0041.tif" />

indicated by solid lines indicate paths 348 and 358 before correction is made by means of reflector member prism assemblies 34 and 35 and reflection paths indicated by dotted lines indicate paths 349 and 359 after correction is made by reflector member prism assemblies 34 and 35.

It can be seen that the paths indicated by the dotted lines are less separated than the paths indicated by the solid lines.

As a result, the size of an image formed on the screen by beams moving along the reflection paths becomes equal to the size of an image formed on the screen by beams moving along the paths. transmission, so the height difference Δ described above can be eliminated.

Meanwhile, it is possible to provide the same effect even when using a polarization beam splitter consisting of a prism 38 having two polarization beam division surfaces 36 and 37 as shown in Figure 17.

That is, the polarization beam splitter can include the polarization beam division surfaces 36 and 37 connected to each other while tilting and prism 38.

A polarization that has a specific direction (for example a P-polarization) is transmitted through the surfaces of

IMPI (Nrrrrww muicano

DCIAFROMDA · industrial division of the polarization beam 36 and 37.

On the other hand, a polarization having another direction (for example an S-polarization) is reflected by the polarization beam splitting surfaces 36 and 37 and the reflected light path is corrected by means of prism 38.

That is, the path of the reflected light is corrected so that the path of the reflected light is less separated.

Meanwhile, refractive members 39 and 40 can be placed on the front of the polarization beam splitter. The function and structure of the refraction members 39 and 40 are the same as those of the refraction members 25 and 26 shown in Figure 7.

Also, a description of the refraction members 39 and 40 will be replaced by a description of the refraction members 25 and 26 as shown in Figure 7 and will therefore be omitted.

In accordance with the present invention as described above, it is possible to reduce the difference between the forward path of the reflected light and the forward path of the transmitted light, thereby obtaining a high-quality stereoscopic image.

Furthermore, it is possible to reduce the distance between the elements of the stereoscopic imaging apparatus compared to the conventional stereoscopic imaging apparatus, thereby reducing the overall size of the stereoscopic imaging apparatus.

Those skilled in the art will appreciate that the present invention

IMPI

<img file="MX340570B_D0042.tif" />

it can be represented in other specific forms than those established herein without departing from the spirit or essential characteristics of the present invention. The aforementioned description should therefore be constructed in all respects as illustrative and not as restrictive. The scope of the invention is to be determined by the reasonable interpretation of the appended claims and all changes within the equivalence range of the invention are intended to be within the scope of the invention.

IMPI

MEXICAN INSTITUTE Dfc LA PROPIEDAD INDUSTRIAL

<img file="MX340570B_D0043.tif" />