JP2000305047A - Optical element, polarized light illuminating device and projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element improved in efficiency for utilizing light by arranging two polarization converting element arrays, with which plural polarized light separating and reflecting planes are alternately arranged through a translucent member, at a prescribed interval so that mutual polarized light separating planes can be confronted. SOLUTION: Polarization converting element arrays 320a and 320b are provided with polarized beam splitter arrays and λ/2 phase difference plates 381 selectively arranged at one part of light emission planes. The polarized beam splitter array is formed by successively sticking plural columnar translucent members 323 respectively having parallelogram-shaped cross sections. A polarized light separating film 331 and a reflecting film 332 are alternately formed on the interface of the translucent member 323. A polarization converting element 350a closest to the optical axis of the polarization converting element array 320a and a polarization converting element 350b closest to the optical axis of the polarization converting element array 320b are oppositely arranged from side to side at an interval Cp. In the interval Cp, dummy parts 370 of the arrays 320a and 320b and a gap Gp thereof are present.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical element for converting incident light into a predetermined polarized light beam, a polarized light illuminating device provided with such an optical element, and a projection display device.

[0002]

2. Description of the Related Art An illumination optical system of a projection display device converts light having a random polarization direction into light having a single polarization direction in order to increase the light use efficiency and obtain a bright display. Is used. like this,
As an optical element (polarization conversion element) for converting light having a random polarization direction into light having one polarization direction, one described in JP-A-7-294906 is known. FIG. 14 is a plan view of such an optical element. This optical element includes a polarizing beam splitter array 20 in which linear polarizing beam splitters 30 having a polarization separating film 36 and linear prisms 40 having a reflecting film 46 are alternately bonded. The light incident surface of the polarizing beam splitter array 20 includes a lens array 10 including a plurality of condenser lenses, and a λ / 2 retardation plate 24 is selectively provided on a part of the light exit surface. Is provided.

As shown in FIG. 14A, a light beam incident on a lens array 10 is condensed by the lens array 10 and converted into a plurality of divided light beams (intermediate light beams). Is incident on the polarizing beam splitter 30 disposed as an incident light including an s-polarized component and a p-polarized component. This incident light is first transmitted to the polarization separation film 36.
Is separated into s-polarized light and p-polarized light. The s-polarized light is reflected almost vertically by the polarization separation film 36 at 45 degrees with respect to the light incident surface, and further vertically reflected by the reflection film 46 at 45 degrees with respect to the light incident surface. Is emitted. On the other hand, the p-polarized light passes through the polarization splitting film 36 as it is, and
The light is converted into polarized light and emitted. Therefore, this optical element is an element that converts all the incident light beams having random polarization directions into s-polarized light beams and emits them.

[0004]

The light beam incident on the lens array 10 is condensed by each condensing lens constituting the lens array 10, and all the light beams are condensed by the polarizing beam splitter corresponding to each condensing lens. Is ideal. However, in the actual light beam incident on the lens array 10, there is a light beam that is not completely condensed and is incident on the prism 40, as shown in FIG. Such a light beam incident on the prism 40 is totally reflected by the reflection film 46 and is incident on the polarization beam splitter 30 disposed next to the light beam. Then, the polarization beam splitter 30
Is split by the polarization splitting film 36 into s-polarized light and p-polarized light. The separated s-polarized light is reflected by the polarization separation film 36, converted into p-polarized light by the λ / 2 retardation plate 24, and emitted. Further, the p-polarized light is transmitted through the polarization separation film 36 and the prism 40 arranged in the transmission direction.
The light is reflected by the reflective film 46 and emitted. Therefore, the light beam incident on this optical element is not a single light beam of s-polarized light,
The light is converted into a light beam including a polarized light beam and emitted. Here, the incident area of the polarization conversion element is divided into an effective incident area EA and an invalid incident area UA. The effective incident area EA is an incident area of the polarization conversion element where the incident light beam is converted into a desired polarized light and emitted. The invalid incident area UA is an incident area of the polarization conversion element where the incident light beam is converted into an undesired polarized light and emitted.
Therefore, in the present conventional example, the incidence surfaces of the plurality of polarization beam splitters 30 are the effective incidence areas EA, and the incidence faces of the plurality of prisms 40 are the invalid incidence areas UA.

When it is desired to use only one kind of polarized light, the light incident on the invalid incident area UA must be cut by a polarizing plate or the like. That is, in such a case, since the emitted light of the p-polarized light is not used, there is a problem that the light use efficiency is reduced.

The present invention has been made to solve the above-mentioned problems in the prior art, and provides a technique for improving the light use efficiency of an optical element used in a polarized light illumination device or a projection display device. The purpose is to:

[0007]

Means for Solving the Problems and Their Functions and Effects In order to solve the above-mentioned problems, a first invention is an optical element, which converts polarized light having a random polarization direction into one kind of polarized light. It has two polarization conversion element arrays, and each of the polarization conversion element arrays has a polarization separation surface that separates polarized light having a random polarization direction into two types of linearly polarized light, and a straight line that is separated by the polarization separation surface. A reflection surface that reflects one of the polarized lights; a plurality of the polarization separation surfaces and the reflection surfaces are alternately arranged via a light-transmitting member; and the two polarization conversion element arrays are arranged at a predetermined interval. It is characterized by being arranged so as to be separated from each other and the polarization splitting surfaces face each other.

The light incident surface of the polarization conversion element array is divided into a first region where the incident light is directly incident on the polarization separation film surface and a second region where the incident light is directly incident on the reflection surface. The light incident on the first incident region is converted into one type of polarized light (effective polarized light), while the light incident on the second incident region is a different invalid polarized light. Converted to light. According to the configuration of the first aspect of the invention, light passing through the predetermined interval is not incident on the second region, so that it is not converted into invalid polarized light but remains optically random as polarized light. Emitted from the element. Therefore, since the effective polarized light included in the random polarized light passing through such a predetermined interval can be used, the light use efficiency of the optical element can be improved.

[0009] Here, of the two end portions of each of the two polarization conversion element arrays, a dummy region in which neither the polarization separation surface nor the reflection surface exists on the predetermined interval side is formed by a translucent member. Preferably, it is formed.

With this configuration, the light path length of the light beam passing through the polarization conversion element array and the light beam passing through the predetermined interval can be made closer. In addition, among the two end portions of each of the two polarization conversion element arrays, the light beam reflected on the end surface on the predetermined interval side cannot be effectively irradiated on the irradiation surface depending on the direction of reflection, and the light cannot be used effectively. is there. With the above configuration, this problem can be mitigated.

In addition, a region where neither the polarization separation surface nor the reflection surface exists on a side other than the predetermined interval side of each of the two end portions of the two polarization conversion element arrays is provided with a translucent member. May be formed.

The optical element according to the first aspect of the present invention is generally arranged such that its center is located between two arranged conversion element arrays, that is, within a predetermined interval, so that its center coincides with the optical axis of the light source. Used. On the other hand, the light emitted from the light source generally tends to be weaker as the distance from the optical axis of the light source increases,
Even if the light incident on the ends of the two polarization conversion element arrays on the side other than the predetermined interval side is converted into a predetermined type of polarized light, there is almost no effect on the light use efficiency. Therefore,
With the above configuration, the number of polarization separation surfaces and reflection surfaces can be reduced, so that an inexpensive optical element can be realized.

According to a second aspect of the present invention, there is provided an optical element, comprising: a lens array in which a plurality of lenses are arranged in a matrix; and one type of polarized light having a random polarization direction fixed to one surface of the lens array. And two polarization conversion element arrays, each of which converts the polarization light having a random polarization direction into two types of linearly polarized light, and the polarization separation surface. A reflection surface that reflects one of the linearly polarized light beams separated by a plane, wherein the polarization separation surface and the reflection surface are alternately arranged in plurality via a light-transmitting member, and the two polarization conversion element arrays are arranged. Are arranged so as to be spaced apart from each other by a predetermined distance so that the polarization splitting surfaces face each other.

In the second invention, as in the first invention, the light incident surface of the polarization conversion element array has a first region where the incident light is directly incident on the polarization separation film surface and a reflection surface. It is divided into a second area to which light is directly incident. It is preferable that all the light beams condensed by the lens array are incident on the first region, but there are also light beams incident on the second region. According to the configuration of the second aspect, among the light beams emitted from the lens array, the light beams that pass through a predetermined interval without being incident on the polarization conversion element array are not incident on the second region. The light is emitted from the optical element as random polarized light without being converted into invalid polarized light. Therefore,
Since the effective polarized light included in the randomly polarized light passing through such a predetermined interval can also be used, the light use efficiency of the optical element can be improved.

Here, the arrangement pitch of the polarization splitting surface and the reflection surface along the light incident surface of the polarization conversion element array is the same as that of the lens array along the arrangement direction of the polarization separation surface and the reflection surface. Preferably, it is larger than 1/2 of the arrangement pitch.

According to the above configuration, since the polarization conversion element array can be configured so that the light beam emitted from the lens array can be more efficiently incident, the light use efficiency of the optical element can be improved.

According to a third aspect of the present invention, there is provided a polarized light illuminating device, comprising: a light source unit; and an optical element that converts light from the light source unit into one type of polarized light and emits the polarized light. A lens array in which a plurality of lenses are arranged in a matrix,
It has two polarization conversion element arrays that are fixed to one surface of the lens array and convert polarization light having a random polarization direction into one type of polarization light, and each of the polarization conversion element arrays has a random polarization direction. A polarized light separating surface that separates the polarized light into two types of linearly polarized light, and a reflecting surface that reflects one of the linearly polarized light beams separated by the polarized light separating surface. Are arranged alternately with a light-transmitting member interposed therebetween, and the two polarization conversion element arrays are arranged at a predetermined interval so that the polarization separation surfaces face each other.

According to the third aspect, since the optical element having high light use efficiency is used, the light use efficiency of the lighting device can be improved.

Further, it is preferable that the polarization splitting surfaces are arranged in accordance with the distribution of light emitted from the lens array.

With this configuration, since the light emitted from the lens array can be effectively used, the efficiency of using the light of the lighting device can be further improved.

Further, a polarization separation surface is disposed at a position closest to the predetermined interval side of the two polarization conversion element arrays, and the center of the polarization separation surface is the center of the plurality of lenses of the lens array. It is preferable that the lens is disposed on the predetermined interval side with respect to the center axis of the lens disposed closest to the polarization separation surface.

The amount of light emitted from the light source is large near the optical axis of the light source. The distribution of the amount of light emitted from the vicinity of the optical axis of the light source is determined by the center of the lens disposed at the position closest to the polarization separation plane disposed at the position closest to the predetermined interval between the two polarization conversion element arrays. The axis is closer to the light source optical axis than the axis. Therefore, according to the above configuration, the light in the vicinity of the light source optical axis can be used effectively, so that the light use efficiency of the lighting device can be further improved.

A fourth invention is a projection display device,
A polarized light illuminator, a modulating means for modulating light emitted from the polarized light illuminator based on a given image signal, and a projection optical means for projecting a light beam modulated by the modulating means; The apparatus includes a light source unit, and an optical element that converts incident light incident from the light source unit into light having a predetermined polarization direction and emits the light, and the optical element includes a plurality of lenses arranged in a matrix. A lens array, having two polarization conversion element arrays that are fixed to one surface of the lens array and convert random polarization light into one kind of polarization light, and each of the polarization conversion element arrays is A polarization separation surface that separates polarized light having a random polarization direction into two types of linearly polarized light, and a reflection surface that reflects one of the linearly polarized lights separated by the polarization separation surface, and the polarization separation surface. The reflection surface and the plurality of polarization conversion element arrays are alternately arranged with a light-transmitting member interposed therebetween, and the two polarization conversion element arrays are arranged so as to be spaced apart from each other by a predetermined distance and to face each other with the polarization separation surfaces facing each other. Features.

According to the fourth aspect of the invention, since the illumination device using the optical element having high light use efficiency is used, the image projected on the projection surface can be brightened.

[0025]

Next, embodiments of the present invention will be described based on examples.

A. Polarized Lighting Apparatus: FIG. 1 is a schematic structural view of a principal part of a polarized light illuminating apparatus 50 to which an embodiment of the present invention is applied, as viewed in plan. The polarized light device 50 includes a light source unit 60.
And a polarization generator 70. The light source unit 60
A light beam having a random polarization direction including an s-polarized component and a p-polarized component is emitted. The luminous flux emitted from the light source unit 60 is converted by the polarization generator 70 into one type of linearly polarized light (for example, s-polarized light) whose polarization direction is almost uniform, and illuminates the illumination area 80.

The light source section 60 includes a light source lamp 101 and a parabolic reflector 102. Light source lamp 10
The light radiated from 1 is reflected in one direction by the parabolic reflector 102, becomes a substantially parallel light flux, and enters the polarization generator 70.

The polarization generator 70 is provided for the first optical element 20.
0 and a second optical element 400. FIG.
FIG. 3 is a perspective view of a first optical element 200. The first optical element 200 has a configuration in which minute light beam splitting lenses 201 having a rectangular outline are arranged in a matrix of M rows in the vertical direction and 2N columns in the horizontal direction. Therefore, there are N columns to the left and N columns to the right from the lens lateral center CL. In this example, M = 10 and N = 4. The first optical element 200 is arranged such that the optical axis coincides with the center of the first optical element 200. Each beam splitting lens 201
Is set so as to be similar to the shape of the illumination area 80. In this embodiment, since the illumination region 80 is assumed to be long in the x direction, the outer shape of the light beam splitting lens 201 on the XY plane is also horizontally long.

The second optical element 400 shown in FIG. 1 includes an optical element 300 and an exit lens 390. And
The optical element 300 and the emission-side lens 390 are arranged such that their centers coincide with the optical axis.

The optical element 300 includes the condenser lens array 31
0 and two polarization conversion element arrays 320a and 320b. The condensing lens array 310 is a lens array having the same configuration as the first optical element 200, and is arranged in the facing direction. The condensing lens array 310 has a role of condensing the first optical element 200 and a plurality of split light beams split by each light beam splitting lens 201. The polarization conversion element arrays 320a and 320b have a role of converting the incident light flux into one type of linearly polarized light (for example, s-polarized light or p-polarized light) and emitting the light. FIG. 3 is an explanatory diagram showing a basic operation of the polarization conversion element array 320b (320a). Incident light having a random polarization direction including an s-polarized component and a p-polarized component is incident on the incident surface of the polarization conversion element. This incident light is first transmitted by the polarization separation film 331 to s.
The light is separated into polarized light and p-polarized light. The s-polarized light is reflected almost vertically by the polarization separation film 331, and is further vertically reflected by the reflection film 332 before being emitted. on the other hand,
The p-polarized light passes through the polarization splitting film 331 as it is. A λ / 2 retardation plate 381 is disposed on the exit surface of the p-polarized light that has passed through the polarization separation film, and the p-polarized light is converted into s-polarized light and emitted. Therefore, most of the light that has passed through the polarization conversion element is emitted as s-polarized light.
When the light emitted from the polarization conversion element is desired to be p-polarized light, the λ / 2 retardation plate 381 is arranged on the emission surface from which the s-polarized light reflected by the reflection film 332 is emitted. I just need. Note that the present invention is characterized by the optical element 300, and will be described later in detail.

The outgoing lens 390 in FIG.
A plurality of split light beams (divided light beams of linearly-polarized light converted by the polarization conversion element arrays 320a and 320b) emitted from the light source 00 are all superimposed so as to illuminate the illumination area 80.

The light beams emitted from the light source unit 60 and incident on the first optical element 200 are separated by the respective light beam splitting lenses 2.
01 is split into an intermediate light flux 202. Intermediate beam 2
02 converges in a plane perpendicular to the optical axis (XY plane in FIG. 1) by the light condensing action of the light beam splitting lens 201 and the condensing lens 311. At the position where the intermediate light beam 202 converges,
As many light source images as the number of light beam splitting lenses 201 are formed. The position where the light source image is formed is near the polarization separation film 331 (see FIG. 3) in the polarization conversion element arrays 320a and 320b.

Of the light beam incident on the optical element 300,
The light is condensed by the condensing lens array 310 and is polarized by the polarization separation film 331.
Is emitted after being converted into one type of linearly polarized light. The light beam emitted from the optical element 300 illuminates the illumination area 80 by the emission side lens 390. Since the illumination area 80 is illuminated with a large number of light beams split by the many light beam splitting lenses 201, the entire illumination area 80 can be evenly illuminated.

B. First Embodiment: FIG. 4 is a front view showing a light incidence surface of an optical element 300 according to a first embodiment, FIG. 5 is a rear view showing an emission surface, FIG. 6 is a cross-sectional view taken along line AA ′ of FIG. FIG. 7 shows a side view.

The optical element 300 is obtained by bonding two polarization conversion element arrays 320a and 320b to a flat light exit surface of a condenser lens array 310 with an optical adhesive. Two polarization conversion element arrays 320a and 320b
Are arranged in opposite directions to the left and right with a predetermined interval Cp therebetween with reference to the horizontal center CL of the condenser lens array 310. The predetermined interval Cp will be described later. The condenser lens array 310 includes the first optical element 200 (FIG. 2).
A condenser lens 311 having a substantially rectangular outline as in
It has a configuration arranged in a matrix with M rows in the vertical direction and 2N columns in the horizontal direction. Therefore, there are N columns to the left and N columns to the right from the center CL in the lateral direction of the lens. In this example, M = 10 and N = 4.

FIG. 8 shows the polarization conversion element arrays 320a and 320a.
It is a perspective view which shows the structure of 20b. The polarization conversion element arrays 320a and 320b are composed of a polarization beam splitter array 340 and a λ / 2 retardation plate 381 selectively disposed on a part of the light exit surface of the polarization beam splitter array 340.
(Shown by oblique lines in the figure). The polarization beam splitter array 340 has a shape in which a plurality of columnar translucent members 323 each having a parallelogram cross section are sequentially bonded. Polarized light separating films 331 and reflective films 332 are formed alternately on the interface of the light transmitting member 323. λ
The / 2 retardation plate 381 is selectively disposed on the light-exiting surface of the polarization separation film 331 or the reflection film 332 in the x-direction mapped portion. In this example, a λ / 2 retardation plate 381 is selectively disposed on the mapping portion in the x direction of the light exit surface of the polarization separation film 331.

As described above with reference to FIG. 3, the incident light that has entered the polarization separation film 331 passes through the polarization separation film 331 and is converted into a predetermined linearly polarized light by the λ / 2 phase plate 381. Linearly polarized light that is emitted
, And is separated into predetermined linearly polarized light that is reflected and emitted by the reflective film 332. Therefore, one polarization separation film 331 and one reflection film 332 adjacent to each other are included.
One block composed of two λ / 2 phase difference plates 381 can be regarded as one polarization conversion element 350.
In the polarization conversion element arrays 320a and 320b, such polarization conversion elements 350 are arranged in a plurality of rows in the x direction. In this embodiment, since the number N of the condensing lens array 310 in the column direction on one side is four, four rows of polarization conversion elements 350 are configured on one side in principle. However,
The portion 360 corresponding to the fourth row of the polarization conversion element has neither the polarization separation film 331 nor the reflection film 332, and is composed of only a light transmitting member. Hereinafter, for the sake of explanation, this portion 360 is referred to as a light transmitting portion. The light transmitting portion 360 will be described later.

In FIG. 8, a dummy portion 370 made of a light-transmitting member is provided on the side surface (end surface) of the polarization conversion element 350 in the leftmost column. The end 372 of the dummy portion 370 on the light incident surface (adhesion surface) side has a rounded or rounded corner. These reasons will be described later.

FIG. 9 shows a polarization beam splitter array 34.
It is explanatory drawing which shows the example of manufacture of No. 0. The polarization beam splitter array 340 includes a polarization separation film 331 and a reflection film 332.
Are arranged alternately, for example, the polarization separation film 33.
The plate glass 321 on which No. 1 and the reflection film 332 are formed and the plate glass 322 on which nothing is formed are alternately bonded with an adhesive 325. At this time, at the beginning and end of the bonding, the plate glass 32 having a thickness different from that of the plate glass 322 is used.
2b (dummy part 370 (FIG. 8)) and 322C (light transmitting part 360 (FIG. 8)) are bonded together. In this case, the dummy section 370 and the light transmitting section 360 can be formed. The plurality of translucent members 32 thus bonded to each other
1, 322, 322b, and 322c are cut substantially parallel to each other at a cut surface (indicated by a broken line in the drawing) that forms a predetermined angle θ with the surface, whereby a light-transmitting block is cut out. The value of θ is preferably about 45 degrees. Also,
The protruding portions at both ends are cut into a substantially rectangular parallelepiped shape. By polishing the surface (cut surface) of the light-transmitting block thus cut out, the polarization beam splitter array 3
40 (FIG. 8) can be obtained. In this specification, a light-transmitting plate material (light-transmitting member) is also referred to as a “substrate”, and a block obtained by bonding a plurality of light-transmitting plate materials or a block cut out from this is referred to as a “substrate block”.
Also called.

FIG. 10 is a partially enlarged view of a section taken along the line AA ′ shown in FIG. Polarization conversion element arrays 320a, 320b
Are merely arranged at symmetrical positions in the opposite direction with respect to the lens center, and their functions are exactly the same. Therefore, the polarization conversion element array 320a will be described below. The light incident surface of the polarization conversion element array 320a is
An effective incident area EA (a light incident surface corresponding to the polarization splitting film 331) into which the light that enters the light 31 and is converted into effective polarized light and the reflective film 332 are converted into invalid polarized light. Incident area UA (reflection film 332)
(A light incident surface corresponding to).
The size Wp of the effective incident area EA and the invalid incident area UA in the x direction is the size W of the condenser lens 311 in the x direction.
L is set equal to 1/2. Also, the condenser lens 311
Of the effective incident area EA is arranged to be equal to the center in the x direction of the effective incident area EA. Here, the effective polarized light converted and used by the polarization conversion element is s-polarized light.

The light condensed by the condensing lens array 310 (light having a random polarization direction including an s-polarized light component and a p-polarized light component) enters the polarization conversion element array 320a. Of such incident light, the light flux L1 incident on the effective incident area EA is separated by the polarization separation film 331 into s-polarized light and p-polarized light as described above with reference to FIG. The s-polarized light is reflected by the polarization separation film 331 and further reflected by the reflection film 33.
The light is reflected at 2 and emitted. The p-polarized light passes through the polarization separation film 331.
, And further converted into s-polarized light by the λ / 2 phase difference plate 381 and emitted. Therefore, the polarization conversion element array 320
Almost all the light incident on the effective incident area EA is converted into s-polarized light and emitted.

The λ / 2 retardation plate 381 is connected to the reflection film 3
If it is selectively provided on the exit surface side of 32, almost only p-polarized light can be selectively emitted from the polarization conversion element.

Light incident on the invalid incident area UA is converted into unnecessary polarized light (p-polarized light in this embodiment) as described in the background art. Normally, since a light shielding plate or the like is provided on the invalid incident area UA to block light, the light use efficiency is reduced. In particular, in a configuration such as the polarized light illuminating device 50 shown in FIG. 1, the amount of light near the optical axis of the light source is the largest, so that the invalid incident area U near the optical axis
When A is present, the light use efficiency is significantly reduced. The present invention has solved the above-mentioned problem, and will be described in detail below.

In this embodiment, the polarization conversion element array 320
The polarization conversion element 350a closest to the optical axis a of FIG. a (see FIG. 10) and the polarization conversion element 350b closest to the optical axis of the polarization conversion element array 320b (FIG. 10) are in opposite directions to the left and right across the interval Cp. It is configured to be arranged. In this interval Cp, the two polarization conversion element arrays 320a, 32
There is a dummy portion 370 of Ob and a gap Gp therebetween. As a result, the condenser lens array 31 near the optical axis
Of the light beams incident on 0, the light beam L2 that cannot be irradiated on the polarization separation film 331 because it cannot be condensed by the condenser lens array 310 passes through the interval Cp where neither the polarization separation film 331 nor the reflection film 332 is emitted, and is emitted as it is. Will do. The transmitted light at the interval Cp is a light beam including s-polarized light that is effective polarized light and p-polarized light that is invalid polarized light. Then, only the necessary polarized light (s-polarized light in this embodiment) of the outgoing light passing through this interval Cp is converted into an effective light beam by providing a polarizing plate on the exit surface side of this interval Cp, for example. It is possible to use. In addition, the polarized light illumination device 50
When (FIG. 1) is applied to a projection display device to be described later, the light-incident surface of the liquid crystal light valve, which is the illumination area 80,
Usually, a polarizing plate is provided. Therefore, in such a case, there is no need to separately provide a polarizing plate.

The light transmitting portion 360 on the outermost side of the polarization conversion element array 320a is a portion through which light from the outermost lens of the condenser lens array 310 passes. The light source of the polarization illuminating device 50 configured using this embodiment is usually arranged at the center of the light incident surface of the condenser lens array 310 on a center line perpendicular to the light incident surface (FIG. 4). The light incident on the outside of the lens array 310, that is, the light incident on the light transmitting portion 360 has the smallest light amount. In such a state, when the incident light from the outermost side of the condenser lens array 310 is used as the polarized light converted by the polarization conversion element, and when the light is used without conversion, the first optical element is used. In most cases, there is almost no difference in the amount of light that can be effectively used in the entire 300 (FIG. 1). Therefore, the condenser lens array 31 in the polarization conversion element array 320a
The light-transmitting portion 360 corresponding to the outermost region of 0 is not a configuration of the polarization conversion element 350 (see FIG. 8), but has only a light-transmitting member, and the λ / 2 phase plate 381 is also omitted. Accordingly, the light beam L3 passing through the outermost lens of the condenser lens array 310 passes through the light transmitting portion 360 and exits as it is. The outgoing light emitted from the light transmitting portion 360 is, like the outgoing light emitted through the above-described interval Cp, an s-polarized light that is valid polarized light and a p-polarized light that is invalid polarized light. . Then, only the necessary polarized light (s-polarized light in the present embodiment) out of the emitted light passing through the light transmitting portion 360 can be made effective by providing a polarizing plate on the light emitting surface side of the light transmitting portion 360, for example. It can be used as a light beam.

FIG. 11 is an explanatory diagram showing the dummy portion 370 shown in FIG. 8 and the end 372 of the dummy portion 370 on the light incident surface side in an enlarged manner. As shown in FIG. 11A, the polarization conversion element arrays 320a and 320b having no dummy section 370 are arranged at a predetermined distance Cp with respect to the lens lateral center CL of the light exit surface of the condenser lens array 310. It is assumed that they are provided and arranged. At this time, a light beam passing through the interval Cp and a light beam passing through the polarization conversion element arrays 320a and 320b have different optical path lengths. If possible, it is desirable to make the optical path lengths as equal as possible.
The end faces 3 of the polarization conversion element arrays 320a and 320b
The light beam Lex1 reflected at 71 may not be used effectively depending on the direction of reflection. Further, the condenser lens array 310 and the polarization conversion element arrays 320a and 320b
Is, for example, as shown in FIG.
5 bonded. At this time, the protruding portion 376 of the adhesive is generated at the predetermined interval Cp. The light beam Lex2 passing through the adhesive protruding portion 376 is irregularly reflected due to the non-uniformity of the adhesive surface, and cannot be used effectively.

Therefore, as shown in FIG. 11B, the dummy portion 370 is made of the same member as the light transmitting member 323 constituting the polarization conversion element arrays 320a and 320b at a predetermined interval Cp.
Was decided. In this case, the problem of the optical path length and the end faces 37 of the polarization conversion element arrays 320a and 320b are reduced.
1 can reduce the problem of the reflected light Lex1. In addition, as shown in FIG. 11B, by providing the dummy portion 370 and rounding or making the corner of the end 372 of the dummy portion 370 on the light incident surface (adhesion surface) side, We decided to reduce the protrusion of the adhesive. The gap Gp at the center may not be provided. However, considering the alignment accuracy of the bonding position when the polarization conversion element arrays 320a and 320b are bonded to the emission surface of the condenser lens array 310, the polarization conversion element arrays 320a and 320b are attached to the emission surface of the collection lens array 310. It is preferable to provide the dummy portion 370 to such an extent that a slight gap Gp is formed at the center portion when the dummy portion 370 is bonded.

C. Second Embodiment FIG. 12 is an explanatory diagram showing an optical element 300 'according to a second embodiment.

In the middle part of FIG. 12, in a configuration such as the polarization illuminating device 50 (FIG. 1), the polarization conversion element array 320 is condensed by the lenses La to Ld of the lens array 310
The light amount distribution of the light irradiating the incident surface of a 'is shown.
In general, the light intensity Ia of the light condensed by the lens La closest to the optical axis is the strongest, and the light condensed by the lens farther from the optical axis is weaker. In FIG. 12, the fourth lens Ld
, The light intensity Id of the light condensed becomes the weakest. The light amount distribution of the light condensed by each of the lenses La to Ld is such that the closer to the optical axis, the closer to the optical axis the closer to the optical axis from a certain lens position (the position of the third lens Lc in FIG. 12). , And the farther from the optical axis, the closer to the opposite of the optical axis. In FIG. 12, the light amount distribution Pc of the light condensed by the lens Lc is substantially distributed at the center of the lens, and the light amount distributions Pb and Pa are gradually closer to the optical axis as the lenses Lb and La are closer to the optical axis. I have. The light amount distribution Pd of the light condensed by the lens Ld is opposite to the optical axis.

In such a case, if the center of the effective incident area of the polarization conversion element array is made to uniformly coincide with the center of the lens, light loss due to the above-described shift in the light amount distribution occurs. In particular, a deviation between the distribution of light emitted from the lens array and the effective incident area near the optical axis of the light source causes a large loss of light. Therefore, the lens array 310
The center of each effective incident area of the polarization conversion element array 320a 'is arranged in accordance with the distribution of light emitted from the lens array 310, that is, in accordance with the peak interval of the distribution of light emitted from the lens array 310. Is preferred. In order to more effectively use the light condensed by the lens array 310, it is preferable that light condensed by a lens closer to the optical axis be used more effectively. In particular, when the amount of light near the light source optical axis is large and the distribution Pa of light emitted from the lens La near the light source optical axis is more deviated toward the light source optical axis than the center optical axis of the lens, the polarization conversion is performed. It is preferable that the center of the effective incident area EA1 closest to the light source optical axis side of the element array 320a 'be approximately aligned with the peak position of the light distribution Pa.

The second embodiment corresponds to the light intensity and the light amount distribution having the dependency on the lens position of the condenser lens array as described above. The optical element 300 'of the second embodiment has basically the same configuration as that of the first embodiment, but includes an effective incident area EA (EA1 to EA4 in the figure) and an invalid incident area UA (UA1 to UA4 in the figure). The difference is that the polarization conversion element arrays 320a 'and 320b' whose width Wp 'in the x direction is larger than 1/2 of the width WL in the x direction of each of the lenses La to Ld of the lens array 310 are used. FIG. 12 shows the polarization conversion element array 320a '
Only the side is shown. The polarization conversion element array 320b 'side is omitted because it is only symmetrical with the polarization conversion element array 320a side with respect to the optical axis.

For example, the polarization conversion element array 320a 'is arranged so that the center of the lens Lc in the third row is equal to the center of the corresponding effective incident area EA3. Normally, the width UA of the invalid incident area (UA1 to UA4 in the figure)
Is equal to the width Wp 'of the effective incident area EA,
One effective incident area EA2, EA1 is provided for each lens Lb, La.
Gradually becomes closer to the optical axis. The rightmost effective incidence area EA4 is located opposite to the optical axis with respect to the center of the lens Ld. As a result, each effective incident area EA1
EA4 substantially coincides with the position of the light quantity distribution of the light emitted from the lens array 310. In particular, a predetermined number of lenses close to the optical axis, for example, two or three lenses have high light intensity, so that the light amount distribution of light condensed by these lenses is:
It is preferable that the corresponding effective incident areas substantially coincide with each other. With such a configuration, the second embodiment can further increase the light use efficiency. It should be noted that how much the width of the effective incident area should be made larger than 1/2 of the width of the lens, and which lens should be arranged based on the effective incident area, depends on the number of lens arrays and each lens. It can be easily obtained experimentally from the relationship between the light quantity distributions.
Further, the width of the effective incident area or the invalid incident area does not need to be limited to be larger than 1/2 of the width of the lens, and is determined by the actual light amount distribution irradiating the light incident surface of the polarization conversion element array. You.

D. Projection Display Device: FIG. 13 is a schematic configuration diagram showing a main part of a projection display device 800 provided with the polarized light illumination device 50 shown in FIG. This projection display device 800
Is a polarization illuminator 50 and a dichroic mirror 80
1,804, reflection mirrors 802,807,809,
It includes relay lenses 806, 808, 810, three liquid crystal light valves 803, 805, 811, a cross dichroic prism 813, and a projection lens 814.

The dichroic mirrors 801 and 804 are
It has a function as a color light separating unit that separates a white light beam into three color lights of red, blue and green. 3 liquid crystal light valves 8
Reference numerals 03, 805, and 811 each have a function as a light modulation unit that modulates three color lights to form an image in accordance with given image information (image signal). The cross dichroic prism 813 has a function as a color light combining unit that forms a color image by combining three color lights.
The projection lens 814 has a function as a projection optical system that projects light representing a synthesized color image on a screen 815.

A blue light green light reflecting dichroic mirror 801
Transmits the red light component of the white light beam emitted from the polarized light illuminating device 50 and reflects the blue light component and the green light component. The transmitted red light is reflected by the reflection mirror 802 and reaches the red light liquid crystal light valve 803. On the other hand, of the blue light and the green light reflected by the first dichroic mirror 801, the green light is reflected by the green light reflecting dichroic mirror 804 and reaches the green light liquid crystal light valve 805. On the other hand, the blue light also passes through the second dichroic mirror 804.

In this embodiment, the optical path length of blue light is the longest of the three color lights. Therefore, for blue light, after the dichroic mirror 804, the incident lens 8
, A light guide unit 850 configured by a relay lens system including a relay lens 808, and an emission lens 810. That is, after transmitting the blue light through the green light reflecting dichroic mirror 804, first, the incident lens 8
06 and the reflection mirror 807, the relay lens 808
It is led to. Further, the light is reflected by the reflection mirror 809 and guided to the emission lens 810, and reaches the liquid crystal light valve for blue light 811. In addition, three liquid crystal light valves 80
3, 805 and 811 correspond to the illumination area 80 in FIG.

The three liquid crystal light valves 803, 805,
811 modulates each color light in accordance with an image signal (image information) provided from an external control circuit (not shown), and generates color light including image information of each color component. The modulated three color lights enter the cross dichroic prism 813. In the cross dichroic prism 813, a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape. Three color lights are synthesized by these dielectric multilayer films,
Light representing a color image is formed. The synthesized light is projected onto a screen 8 by a projection lens 814 which is a projection optical system.
15, and the image is enlarged and displayed.

In the projection display device 800, liquid crystal light valves 803, 8 of a type for modulating a light beam (s-polarized light or p-polarized light) having a specific polarization direction as light modulating means.
05, 811 are used. Usually, a polarizing plate (not shown) is attached to each of the liquid crystal light valves on the incident side and the output side. Therefore, only a predetermined polarization direction, for example, s-polarized light, is modulated and enters the cross dichroic prism 813. At this time,
Of the light beams incident on the optical element 300, the light beams condensed by the condensing lens array 310 and irradiated on the polarization separation film 331 are all converted into s-polarized light as shown in FIG. 5 described above. Is emitted. The light flux emitted from the optical element 300 illuminates the liquid crystal light valves 803, 805, 811 by the emission side lens 390.

Further, of the light beams incident on the optical element 300, the light beams which are not condensed by the condensing lens array 310 and are irradiated on the reflection film 332 are converted into p-polarized light as described in the background art. And emitted, the liquid crystal light valve 8
03,805,811. However, as described above, a polarizing plate is provided on the incident surface of the liquid crystal light valves 803, 805, 811 so as to use only s-polarized light, and p-polarized light is blocked. On the other hand, the luminous flux that has passed through the interval Cp (FIG. 10) in the optical element 300 according to the embodiment of the present invention is emitted without being converted into polarized light, and the liquid crystal light valves 803 and 80 are emitted.
Illuminate 5,811. Since this illumination light is white light containing an s-polarized light component that can be used by the liquid crystal light valves 803, 805, and 811, the liquid crystal light valves 803, 805
It is possible to use only the s-polarized light component of the light irradiated to 5,811. Therefore, the projection display device 800 shown in FIG. 13 uses the polarized light illuminating device 50 using the optical element 300 according to the embodiment, and thus has an advantage that the light use efficiency is higher than in the related art.

As described above, by using the optical element according to this embodiment, it is possible to increase the light use efficiency of the projection display apparatus as compared with the related art. Therefore, the image projected on the screen 815 can be made brighter.

It should be noted that the present invention is not limited to the above examples and embodiments, but can be implemented in various modes without departing from the scope of the invention.
For example, the following modifications are possible.

The polarized light illuminating device according to the present invention can be applied not only to the projection display device shown in FIG. 13, but also to various other devices. For example, instead of a color image,
The polarizing beam splitter array according to the present invention can be applied to a projection display device that projects a black-and-white image. In this case, in the apparatus of FIG. 13, only one liquid crystal light valve is required, and the color light separating means for separating the light beam into three colors and the color light combining means for combining the light beams of three colors can be omitted. Further, the present invention can be applied to a projection type color display device using only one light valve. Further, the present invention can be applied to an image display device using polarized illumination light, such as a projection display device using a reflection type light valve or a rear display device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of a polarized light illuminating device 50 to which an embodiment of the present invention is applied, as viewed in plan.

FIG. 2 is a perspective view of a first optical element 200.

FIG. 3 is an explanatory diagram showing a basic operation of the polarization conversion element array 320b (320a).

FIG. 4 is a front view showing a light incident surface of the optical element 300 according to the first embodiment.

FIG. 5 is a rear view showing a light emitting surface of the optical element 300 according to the first embodiment.

FIG. 6 is a sectional view taken along line A-A ′ of FIG. 5;

FIG. 7 is a side view of the optical element 300 according to the first embodiment.

FIG. 8 is a perspective view showing a configuration of a polarization conversion element array 320a, 320b.

FIG. 9 is an explanatory view showing a manufacturing example of the polarizing beam splitter array 340.

FIG. 10 is a partially enlarged view of a section taken along line A-A ′ shown in FIG. 5;

FIG. 11 is an explanatory diagram showing an enlarged view of a dummy portion 370 shown in FIG. 8 and an end 372 of the dummy portion 370 on the light incident surface side.

FIG. 12 is an explanatory diagram illustrating an optical element 300 ′ according to a second embodiment.

FIG. 13 is a schematic configuration diagram showing a main part of a projection display device 800 including the polarized light illumination device 50 shown in FIG.

FIG. 14 is a plan view of a conventional optical element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Lens array 20 ... Polarization beam splitter array 30 ... Polarization beam splitter 36 ... Polarization separation film 40 ... Prism 46 ... Reflection film 50 ... Polarization illumination device 60 ... Light source part 70 ... Polarization generation device 80 ... Illumination area 90 ... Illumination area 101 .., Light source lamp 102, parabolic reflector 200, first optical element 201, light beam splitting lens 202, intermediate light beam 300, optical element 310, condensing lens array 311, condensing lens 311 c, center 320 a, 320 b, polarization conversion element Arrays 321, 322, 322b, 322c: translucent member 323: translucent member (plate glass) 325: adhesive 331: polarization separation film 332: reflection film 340: polarization beam splitter array 350: polarization conversion element 350a: polarization conversion Element 350b ... Polarization conversion element 360 ... Transparent part 37 0 ... Dummy part 371 ... End face 372 ... End part 375 ... Adhesive 376 ... Adhesive protruding part 381 ... λ / 2 phase difference plate 390 ... Emission side lens 400 ... Second optical element 800 ... Projection display device 801 804 ... dichroic mirror 802, 807, 809 ... reflection mirror 803, 805, 811 ... liquid crystal light valve 806 ... entrance lens 807 ... reflection mirror 808 ... relay lens 809 ... reflection mirror 810 ... exit lens 813 ... cross dichroic prism 814 ... projection lens 815: screen 850: light guide means CL: lens lateral center Cp: interval EA: effective incident area EA1, EA2, EA3, EA4: effective incident area Gp: gap Ia, Ib, Ic, Id: light intensity Lex1: light flux Lex2 ... Light flux L1 Light flux L2 Light flux L3 Light flux La, Lb , Lc, Ld: Lens Pa, Pb, Pc, Pd: Light intensity distribution UA: Invalid incident area UA1, UA2, UA3, UA4: Invalid incident area

Claims (22)

[Claims] 1. A polarization conversion element array for converting polarized light having a random polarization direction into one type of polarized light, wherein each of the polarization conversion element arrays converts two types of polarized light having a random polarization direction. A polarization separating surface that separates into linearly polarized light, and a reflecting surface that reflects one of the linearly polarized lights separated by the polarization separating surface, wherein the polarization separating surface and the reflecting surface are a light-transmitting member. The two polarization conversion element arrays are arranged alternately at a predetermined interval,
An optical element characterized by being arranged such that the polarization separation surfaces face each other. 2. The method according to claim 1, wherein, of the two end portions of each of the two polarization conversion element arrays, a dummy region in which neither the polarization separation surface nor the reflection surface exists is provided on the predetermined interval side. An optical element formed of an optical member. 3. The polarization separation surface according to claim 1, wherein, of both ends of each of the two polarization conversion element arrays, a side other than the predetermined spacing side is provided.
An optical element, wherein a region where none of the reflection surfaces is present is formed of a translucent member. 4. A lens array in which a plurality of lenses are arranged in a matrix, and two polarization converters fixed to one surface of the lens array and converting polarized light having a random polarization direction into one type of polarized light. Each of the polarization conversion element arrays has a polarization separation surface that separates polarized light having a random polarization direction into two types of linearly polarized light, and a linearly polarized light separated by the polarization separation surface. A reflection surface that reflects one of the polarization conversion surfaces, the polarization separation surface and the reflection surface are alternately arranged in plurality via a light-transmitting member, and the two polarization conversion element arrays are separated by a predetermined interval.
An optical element characterized by being arranged such that the polarization separation surfaces face each other. 5. The transparent region according to claim 4, wherein, of the two end portions of each of the two polarization conversion element arrays, a dummy region having neither the polarization separation surface nor the reflection surface is provided on the predetermined interval side. An optical element formed of an optical member. 6. The optical element according to claim 5, wherein a corner of the dummy area on the side of the predetermined space is removed. 7. The polarization separation surface according to claim 4, wherein, of the two end portions of each of the two polarization conversion element arrays, a side other than the predetermined spacing side is provided with the polarization separation surface.
An optical element, wherein a region where none of the reflection surfaces is present is formed of a translucent member. 8. The polarization conversion element array according to claim 4, wherein an arrangement pitch of the polarization separation surface and the reflection surface along a light incident surface of the polarization conversion element array is the same as the polarization separation surface and the reflection surface. An optical element characterized by being larger than 1/2 of an array pitch of the lens array along an array direction. 9. A light source comprising: a light source unit; and an optical element that converts light from the light source unit into one type of polarized light and emits the polarized light, wherein the optical element includes a plurality of lenses arranged in a matrix. An array, and two polarization conversion element arrays fixed to one surface of the lens array and configured to convert polarized light having a random polarization direction into one type of polarized light. A polarization separation surface that separates the polarized light having a random direction into two types of linearly polarized light, and a reflection surface that reflects one of the linearly polarized lights separated by the polarization separation surface, and the polarization separation surface and the polarization separation surface. A plurality of reflective surfaces are alternately arranged via a translucent member, and the two polarization conversion element arrays are separated by a predetermined distance,
A polarized light illuminating device, wherein the polarized light separating surfaces are arranged so as to face each other. 10. The dummy region according to claim 9, wherein, of the two end portions of each of the two polarization conversion element arrays, a dummy region having neither the polarization splitting surface nor the reflection surface is provided on the predetermined interval side. A polarized illumination device formed of an optical member. 11. The polarized-light illuminating device according to claim 10, wherein corner portions of the dummy region on the predetermined interval side are removed. 12. The polarization separation surface according to claim 9, wherein, of both end portions of each of the two polarization conversion element arrays, a side other than the predetermined interval side is provided with the polarization separation surface;
A polarization illuminating device, wherein a region where none of the reflection surfaces is present is formed of a translucent member. 13. The polarized light illuminating device according to claim 9, wherein the polarized light separating surfaces are arranged in accordance with a distribution of light emitted from the lens array. 14. The polarization separation surface according to claim 9, wherein a polarization separation surface is disposed at a position closest to the predetermined interval side of the two polarization conversion element arrays. A polarization illuminating device, wherein a plurality of lenses of a lens array are arranged on the predetermined interval side with respect to a center axis of a lens arranged closest to the polarization separation surface. 15. The polarization conversion element array according to claim 9, wherein an arrangement pitch of the polarization separation surface and the reflection surface along a light incident surface of the polarization conversion element array is the same as that of the polarization separation surface and the reflection surface. A polarized light illuminating device characterized in that it is larger than 1/2 of the array pitch of the lens array along the array direction. 16. A polarized light illuminating device, a modulating means for modulating light emitted from the polarized light illuminating device based on a given image signal, and a projection optical means for projecting a light beam modulated by the modulating means. The polarized light illuminating device includes: a light source unit; and an optical element that converts incident light incident from the light source unit into light having a predetermined polarization direction and emits the light. The optical element includes a plurality of lenses in a matrix. A lens array fixed in one side of the lens array, and two polarization conversion element arrays for converting polarized light having a random polarization direction into one kind of polarized light. Each of the arrays has a polarization separation surface that separates polarized light having a random polarization direction into two types of linearly polarized light, and a reflection surface that reflects one of the linearly polarized light separated by the polarization separation surface. A plurality of the polarization splitting surfaces and the reflecting surfaces are alternately arranged via a translucent member, and the two polarization conversion element arrays are separated by a predetermined distance.
And a projection display device, wherein the polarization separation surfaces are arranged so as to face each other. 17. The transparent region according to claim 16, wherein, of the two end portions of each of the two polarization conversion element arrays, a dummy region having neither the polarization separation surface nor the reflection surface is provided on the predetermined interval side. A projection type display device formed of an optical member. 18. The projection display device according to claim 17, wherein corners of the dummy area on the side of the predetermined space are removed. 19. The polarization separation surface according to claim 16, wherein, of the two end portions of each of the two polarization conversion element arrays, the polarization separation surface is provided on a side other than the predetermined interval side.
A projection display device, wherein a region where none of the reflection surfaces exists is formed by a translucent member. 20. The projection display according to claim 16, wherein the polarization splitting surfaces are arranged in accordance with a distribution of light emitted from the lens array. 21. The polarization separation surface according to claim 16, wherein a polarization separation surface is disposed at a position closest to the predetermined interval side of the two polarization conversion element arrays, and a center of the polarization separation surface is A projection display device, wherein a plurality of lenses of a lens array are arranged on the predetermined interval side with respect to a center axis of a lens arranged closest to the polarization separation surface. 22. The polarization conversion element array according to claim 16, wherein an arrangement pitch of the polarization separation surface and the reflection surface along a light incident surface of the polarization conversion element array is the same as that of the polarization separation surface and the reflection surface. A projection type display device, wherein the pitch is larger than 1/2 of an array pitch of the lens array along an array direction.