JP3367501B2 - Optical element manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical element that converts incident light into a predetermined polarized light beam.

[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 unidirectional polarization direction in order to improve light utilization efficiency and obtain a bright display. The method used 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, the 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 polarization beam splitter array 20 in which a linear polarization beam splitter 30 having a polarization separation film 36 and a linear prism 40 having a reflection film 46 are alternately laminated. Further, the light incident surface of the polarization beam splitter array 20 is provided with the lens array 10 including a plurality of condenser lenses, and the λ / 2 phase difference plate 24 is selectively provided on a part of the light emitting surface. It is provided.

As shown in FIG. 14A, the light beam incident on the lens array 10 is condensed by the lens array 10 and converted into a plurality of divided light beams (intermediate light beams), which correspond to the lens array 10. The incident light including the s-polarized light component and the p-polarized light component is made incident on the polarization beam splitter 30 that is arranged as a unit. The incident light is first reflected by the polarization separation film 36.
Is separated into s-polarized light and p-polarized light. The s-polarized light is reflected almost perpendicularly by the polarization splitting film 36 that makes an angle of 45 degrees with respect to the light incident surface, and is further perpendicularly reflected by the reflection film 46 that makes an angle of 45 degrees with respect to the light incident surface, and is reflected from the prism 40. Is emitted. On the other hand, the p-polarized light passes through the polarization separation film 36 as it is, and is transmitted by the λ / 2 phase difference plate 24 to s
It is converted into polarized light and emitted. Therefore, this optical element is an element that converts all incident light fluxes having random polarization directions into s-polarized light flux and emits them.

[0004]

The luminous flux incident on the lens array 10 is condensed by each condenser lens forming the lens array 10, and all the luminous flux is transmitted to the polarization beam splitter corresponding to each condenser lens. Is ideally incident. However, as shown in FIG. 14B, the light flux that has actually entered the lens array 10 includes a light flux that is not completely condensed and enters the prism 40. Such a light flux that has entered the prism 40 is totally reflected by the reflective film 46 and then enters the polarizing beam splitter 30 disposed next to it. Then, the polarization beam splitter 30
The light beam incident on is separated into s-polarized light and p-polarized light by the polarization separation film 36. The separated s-polarized light is reflected by the polarization separation film 36, converted into p-polarized light by the λ / 2 phase difference plate 24, and emitted. Further, the p-polarized light passes through the polarization separation film 36 and is arranged in the prism 40 in the transmission direction.
The light is reflected by the reflection film 46 and emitted. Therefore, the light flux incident on this optical element is not a single light flux of s-polarized light but p
It 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 in which the incident light flux is converted into desired polarized light and emitted. The invalid incident area UA is an incident area of the polarization conversion element in which the incident light flux is converted into undesired polarized light and emitted.
Therefore, in this conventional example, the incident surfaces of the plurality of polarization beam splitters 30 are the effective incident areas EA, and the incident surfaces of the plurality of prisms 40 are the invalid incident areas UA.

When it is desired to use only one type of polarized light, the light incident on the ineffective 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 described above is not used, there is a problem that the light use efficiency decreases.

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

[0007]

Means for Solving the Problems and Their Actions / Effects In order to solve the above problems, the first optical element of the present invention is manufactured.
The manufacturing method is as follows: (a) First light-transmitting property in which a polarization separation film and a reflection film are formed.
A member, the polarization separation film and the reflection film are formed.
A plurality of second light-transmissive members that are not present are alternately laminated and
At the beginning and end of bonding, the polarization separation film and the reflection
A film is not formed, and the second translucent member
And a third translucent member with a different thickness
And (b) cutting the block at a predetermined angle so that the blocks are substantially parallel to each other.
Form a translucent block having a light incident surface and a light emitting surface
And (c) attaching a lens array to the surface of the translucent block.
And a step of matching .

[0008]

[0009]

[0010]

[0011]

In the second method for manufacturing an optical element, (a) the first light-transmissive member having a polarization separation film and a reflection film formed thereon, and the polarization separation film and the reflection film not formed. A plurality of second light-transmissive members are alternately laminated, the polarization separation film and the reflection film are not formed at the beginning and the end of the lamination, and the second light-transmissive member is formed. And a step of forming a block by laminating a third translucent member having a different thickness, and (b) cutting the block at a predetermined angle to have a substantially parallel light incident surface and light emitting surface. A step of forming a light-transmitting block , and (c) a plurality of the light-transmitting blocks are separated from each other by the polarization components.
Attach to the lens array with the membranes facing each other
And a step of applying .

In the above first and second optical element manufacturing methods , further, before the step (c), the light incident surface and the light emitting surface of the light transmissive block are polished. The process may be provided.

Here, it is preferable that the third translucent member is thicker than the first translucent member and the second translucent member.

[0015]

[0016]

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described based on examples.

A. Polarized Illumination Device: FIG. 1 is a schematic configuration diagram of a main part of a polarized illumination device 50 to which an embodiment of the present invention is applied, viewed in plan. The polarized illumination device 50 includes a light source unit 60 and a polarized light generation device 70. The light source unit 60 emits a luminous flux having a random polarization direction including an s-polarized component and a p-polarized component. The light flux emitted from the light source unit 60 is one type of linearly polarized light (for example, s-polarized light) whose polarization directions are substantially aligned by the polarization generator 70.
To illuminate the illumination area 80.

The light source section 60 comprises a light source lamp 101 and a parabolic reflector 102. Light source lamp 10
The light emitted from No. 1 is reflected in one direction by the parabolic reflector 102, becomes a substantially parallel light beam, and enters the polarization generation device 70.

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

The second optical element 400 of FIG. 1 comprises an optical element 300 and an exit lens 390. And
The optical element 300 and the exit lens 390 are arranged so that their centers coincide with the optical axis.

The optical element 300 includes a condenser lens array 31.
0 and two polarization conversion element arrays 320a and 320b are provided. The condenser lens array 310 is a lens array having the same configuration as the first optical element 200, and is arranged in opposite directions. The condensing lens array 310 has a role of condensing the plurality of divided light beams divided by each light beam dividing lens 201 together with the first optical element 200. 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 the basic operation of the polarization conversion element array 320b (320a). Incident light having a random polarization direction including an s-polarization component and a p-polarization component is incident on the incident surface of the polarization conversion element. This incident light is first reflected by the polarization separation film 331 as s
It is separated into polarized light and p-polarized light. The s-polarized light is reflected almost vertically by the polarization separation film 331, further vertically reflected by the reflection film 332, and then emitted. on the other hand,
The p-polarized light passes through the polarization separation film 331 as it is. A λ / 2 phase difference plate 381 is arranged on the emission 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 to be p-polarized light, the λ / 2 phase difference plate 381 may be arranged on the emission surface from which the s-polarized light reflected by the reflection film 332 is emitted. Good. The present invention is characterized by the optical element 300, and the details will be described later.

The exit side lens 390 of FIG.
00 has a role of superimposing so that all of the plurality of split light beams (split light beams of linearly polarized light converted by the polarization conversion element arrays 320a and 320b) illuminate the illumination area 80.

The luminous flux emitted from the light source section 60 and incident on the first optical element 200 is divided into the respective luminous flux splitting lenses 2.
The light beam is split into an intermediate light beam 202 by 01. Intermediate luminous flux 2
02 is converged within a plane (XY plane in FIG. 1) perpendicular to the optical axis by the condensing action of the light beam splitting lens 201 and the condensing lens 311. At the position where the intermediate luminous flux 202 converges,
The same number of light source images as the 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 flux incident on the optical element 300,
The polarization separation film 331 is condensed by the condenser lens array 310.
The light flux irradiated with is converted into one type of linearly polarized light and emitted. The light flux emitted from the optical element 300 illuminates the illumination area 80 by the emission side lens 390. Since the illumination area 80 is illuminated by the large number of light beams divided by the large number of light beam dividing lenses 201, the entire illumination area 80 can be uniformly illuminated.

B. First Embodiment of Optical Element: FIG. 4 is a front view showing a light incident surface of an optical element 300 according to the first embodiment, FIG. 5 is a rear view showing an emission surface, and FIG. 6 is AA ′ of FIG. A sectional view and FIG. 7 are side views.

In this optical element 300, two polarization conversion element arrays 320a and 320b are attached to the flat light emitting surface of the 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 lateral center CL of the condenser lens array 310. The predetermined interval Cp will be described later. The condenser lens array 310 includes a first optical element 200 (FIG. 2).
The condensing lens 311 having a substantially rectangular contour in the same manner as
It is arranged in a matrix with M rows in the vertical direction and 2N columns in the horizontal direction. Therefore, from the center CL in the lateral direction of the lens, there are N columns to the left and N columns to the right. In this example, M = 10 and N = 4.

FIG. 8 shows 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 include a polarization beam splitter array 340 and a λ / 2 phase difference plate 381 selectively arranged on a part of a light emitting surface of the polarization beam splitter array 340.
(Indicated by diagonal 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 cross section of a parallelogram are sequentially attached. Polarization separation films 331 and reflection films 332 are alternately formed on the interface of the translucent member 323. λ
The / 2 phase difference plate 381 is selectively arranged on the image-forming portion in the x direction on the light emission surface of the polarization separation film 331 or the reflection film 332. In this example, the λ / 2 retardation plate 381 is selectively arranged on the image-forming portion in the x direction on the light emission surface of the polarization separation film 331.

As described above with reference to FIG. 3, the incident light incident on 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 difference plate 381. And emitted linearly polarized light, and a polarization separation film 331.
And is separated into predetermined linearly polarized light which is reflected by the reflection film 332 and emitted. Therefore, one polarization separation film 331 and one reflection film 332 that are adjacent to each other are included.
One block composed of one λ / 2 retardation plate 381 can be regarded as one polarization conversion element 350.
The polarization conversion element arrays 320a and 320b are such that the polarization conversion elements 350 are arranged in a plurality of rows in the x direction. In this embodiment, the number N in the column direction on one side of the condenser lens array 310 is 4, so that in principle, four columns of polarization conversion elements 350 are formed on one side. However,
The portion 360 corresponding to the fourth-row polarization conversion element does not have the polarization separation film 331 or the reflection film 332, and is composed of only a light-transmissive member. Hereinafter, for the sake of explanation, this portion 360 will be referred to as a light transmitting portion. The transparent portion 360 will be described later.

In FIG. 8, a dummy portion 370 formed of a light transmissive member is provided on the side surface (end surface) of the polarization conversion element 350 on the leftmost column. Further, the end portion 372 of the dummy portion 370 on the light incident surface (adhesion surface) side is rounded or rounded. These reasons will be explained later.

FIG. 9 shows a polarization beam splitter array 34.
It is explanatory drawing which shows the example of manufacture of 0. The polarization beam splitter array 340 includes a polarization separation film 331 and a reflection film 332.
So that they are alternately arranged, for example, the polarization separation film 33
The plate glass 321 on which 1 and the reflection film 332 are formed and the plate glass 322 on which nothing is formed are alternately bonded by the adhesive 325. At this time, at the beginning and the end of the bonding, the plate glass 32 having a thickness different from that of the plate glass 322 is formed.
2b (dummy part 370 (FIG. 8)) and 322C (translucent part 360 (FIG. 8)) are bonded together. In this way, the dummy part 370 and the light transmitting part 360 can be formed. A plurality of translucent members 32 thus bonded to each other
The translucent block is cut out by cutting 1, 322, 322b, 322c substantially parallel to a cutting surface (shown by a broken line in the drawing) forming a predetermined angle θ with the surface. The value of θ is preferably about 45 degrees. Also,
The projecting portions at both ends are cut into a substantially rectangular parallelepiped shape. By polishing the surface (cut surface) of the translucent block cut out in this way, the polarization beam splitter array 3
40 (FIG. 8) can be obtained. In this specification, the translucent plate material (translucent member) is also referred to as a “substrate”, and a block formed by adhering a plurality of translucent plate materials or a block cut out from the block is a “substrate block”.
Also called.

FIG. 10 is a partially enlarged view of the AA 'cross section shown in FIG. Polarization conversion element arrays 320a and 320b
The polarization conversion element array 320a will be described below because the elements have exactly the same functions, except that they are arranged symmetrically with respect to the center of the lens. The light incident surface of the polarization conversion element array 320a is the polarization separation film 3
31 is incident on the effective incident area EA (the incident surface of the light corresponding to the polarization separation film 331) on which the light that is converted to the effective polarized light is incident, and the reflective film 332, and is converted to the invalid polarized light. Invalid incident area UA (reflecting film 332
And the incident surface of light) are alternately arranged.
The size Wp of the effective incident area EA and the invalid incident area UA in the x direction is the size Wp of the condenser lens 311 in the x direction.
It is equal to 1/2 of L. Also, a condenser lens 311
Center 311c is arranged so as to be equal to the center of the effective incident area EA in the x direction. Here, the effective polarized light converted and used by the polarization conversion element is s-polarized light.

The light condensed by the condenser lens array 310 (light having a random polarization direction including the s-polarization component and the p-polarization 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.
It is reflected at 2 and emitted. The p-polarized light is polarized by the polarization separation film 331.
Is further transmitted, and further converted into s-polarized light by the λ / 2 retardation plate 381 and emitted. Therefore, the polarization conversion element array 320
Almost all the light incident on the effective incident area EA of a is converted into s-polarized light and emitted.

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

The light incident on the invalid incident area UA is converted into unnecessary polarized light (p-polarized light in this embodiment) as described in the prior art. Normally, a light-shielding plate or the like is provided on the invalid incident area UA to block light, so that the utilization efficiency of light is reduced. Particularly, in the configuration such as the polarized illumination device 50 shown in FIG. 1, the amount of light in the vicinity of the optical axis of the light source becomes the largest, so that the invalid incident area U in the vicinity of the optical axis.
When A is present, the light utilization efficiency is significantly reduced. The present invention solves the above problems, and the details thereof will be described below.

In this embodiment, the polarization conversion element array 320 is used.
The polarization conversion element 350a closest to the optical axis of 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 opposite to each other with a space Cp in between. It is configured to be placed. In this space Cp, two polarization conversion element arrays 320a and 32a are provided.
There is a dummy part 370 of 0b and a gap Gp between them. As a result, the condenser lens array 31 near the optical axis
Of the light fluxes incident on 0, the light flux L2 that cannot be irradiated onto the polarization separation film 331 because it cannot be condensed by the condenser lens array 310, passes through the interval Cp having neither the polarization separation film 331 nor the reflection film 332, and is emitted as it is. Will be done. The light passing through the interval Cp is a light flux including s-polarized light that is effective polarized light and p-polarized light that is ineffective polarized light. Then, of the emitted light passing through the interval Cp, only the necessary polarized light (s-polarized light in this embodiment) is converted into an effective light flux by providing a polarizing plate on the exit surface side of the interval Cp. It is possible to use. In addition, the polarized illumination device 50
When (FIG. 1) is applied to the projection display device described later, the incident surface of the liquid crystal light valve, which is the illumination area 80, is
Usually, a polarizing plate is provided. Therefore, in such a case, it is not necessary to separately provide a polarizing plate.

The light transmitting portion 360, which is the outermost side of the polarization conversion element array 320a, is a portion through which the light from the outermost lens of the condenser lens array 310 passes. The light source of the polarized illumination device 50 configured using this embodiment is normally arranged at the center of the light incident surface of the condenser lens array 310 and on the center line perpendicular to the light incident surface (FIG. 4). The light amount incident on the outer side of the lens array 310, that is, the light transmitting portion 360 is the smallest. In such a state, the first optical element is used 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 it is used as it is without being converted. In many 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
This light-transmitting portion 360 corresponding to the outermost side of 0 has only the light-transmitting member without the structure of the polarization conversion element 350 (see FIG. 8), and the λ / 2 retardation plate 381 is also deleted. As a result, the light flux L3 passing through the outermost lens of the condenser lens array 310 passes through the light transmitting portion 360 and is emitted as it is. The emitted light emitted from the light transmitting portion 360 is s-polarized light that is effective polarized light and p-polarized light that is ineffective polarized light, like the emitted light that passes through the interval Cp and is emitted. Is a light flux including. Of the emitted light that passes through the light transmitting portion 360, only the necessary polarized light (s-polarized light in this embodiment) is effectively provided, for example, by providing a polarizing plate on the light emitting surface side of the light transmitting portion 360. It can be used as a luminous flux.

FIG. 11 is an explanatory view showing, in an enlarged manner, the dummy portion 370 and the end portion 372 on the light incident surface side of the dummy portion 370 shown in FIG. As shown in FIG. 11A, the polarization conversion element arrays 320a and 320b having no dummy portion 370 have a predetermined distance Cp with respect to the lens lateral center CL of the light emitting surface of the condenser lens array 310. It is assumed that they are provided and arranged. At this time, the light paths passing through the interval Cp and the light paths passing through the polarization conversion element arrays 320a and 320b have different optical path lengths, but it is desirable to make the optical path lengths as equal as possible if possible.
In addition, the end faces 3 of the polarization conversion element arrays 320a and 320b
The light flux Lex1 reflected by 71 may not be effectively used 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.
Bonded by 5. At this time, the adhesive protrusion portion 376 is generated at the predetermined interval Cp. The light flux Lex2 passing through the adhesive protruding portion 376 is irregularly reflected due to the nonuniformity of the adhesive surface, and cannot be effectively used.

Therefore, as shown in FIG. 11B, the dummy portion 370 is made of the same material as the transparent member 323 which constitutes the polarization conversion element arrays 320a and 320b at a predetermined interval Cp.
Will be provided. In this way, the problem of the optical path length and the end faces 37 of the polarization conversion element arrays 320a and 320b are prevented.
The problem of the reflected light Lex1 at 1 can be alleviated. Further, as shown in FIG. 11 (B), by providing a dummy portion 370 and rounding or rounding the corner of the end portion 372 of the dummy portion 370 on the light incident surface (bonding surface) side, We decided to reduce the protrusion of the adhesive. In addition, the gap Gp in the central portion may be omitted. However, considering the alignment accuracy of the bonding positions 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 arranged on the emission surface of the condenser lens array 310. It is preferable to provide the dummy portion 370 to such an extent that a slight gap Gp is formed in the central portion when the dummy portion 370 is bonded to the dummy portion 370.

C. Second Example of Optical Element: FIG. 12 is an explanatory diagram showing an optical element 300 ′ of a second example.

In the middle part of FIG. 12, in a configuration such as the polarized illumination device 50 (FIG. 1), the light is condensed by the respective lenses La to Ld of the lens array 310 and the polarization conversion element array 320.
The light amount distribution of the light that illuminates 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 becomes the strongest, and the light condensed by the lens farther from the optical axis becomes weaker, and in FIG. 12, the fourth lens Ld.
The light intensity Id of the light condensed at is the weakest. In addition, the light amount distribution of the light condensed by each of the lenses La to Ld is closer to the optical axis with respect to the lens center as the distance from the optical axis is closer to a certain lens position (the position of the third lens Lc in FIG. 12). And the distribution is closer to the opposite side of the optical axis as it is farther from the optical axis. In FIG. 12, the light amount distribution Pc of the light condensed by the lens Lc is distributed almost in 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. There is. Further, the light amount distribution Pd of the light condensed by the lens Ld is on the opposite side of the optical axis.

In such a case, if the center of the effective incident area of the polarization conversion element array is made to coincide with the lens center, the light loss due to the deviation of the light quantity distribution as described above occurs. Particularly, in the vicinity of the optical axis of the light source, the deviation between the distribution of light emitted from the lens array and the effective incident area causes a large light loss. Therefore, the lens array 310
It is possible to arrange the centers of the respective effective incident areas of the polarization conversion element array 320a 'in accordance with the distribution of the light emitted from the lens array 310, that is, in accordance with the peak intervals of the distribution of the light emitted from the lens array 310. preferable. Further, in order to use the light condensed by the lens array 310 more effectively, it is preferable that the light condensed by the lens closer to the optical axis be used more effectively. In particular, when the light amount near the light source optical axis is large and the distribution Pa of the light emitted from the lens La near the light source optical axis is biased toward the light source optical axis side with respect to the central optical axis of the lens, polarization conversion is performed. Effective incident area E closest to the light source optical axis side of the element array 320a '
It is preferable that the center of A1 is substantially aligned with the peak position of the light distribution Pa.

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

For example, the polarization conversion element array 320a 'is arranged so that the center of the lens Lc in the third column and the center of the corresponding effective incident area EA3 are made equal. 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, so
The two effective incident areas EA2 and EA1 are formed by the lenses Lb and La.
It gradually becomes closer to the optical axis with respect to the center of. The rightmost effective incident area EA4 is located on the opposite side of 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 amount 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 to three lenses, have high light intensity, and therefore the light quantity distribution of the light condensed by these lenses,
It is preferable that the corresponding effective incident areas substantially coincide with each other. With such a configuration, the second embodiment can further improve the light utilization efficiency. Note that the number of lens arrays and the number of lens arrays are used to determine how much the effective incident area width is increased with respect to ½ of the lens width and which effective incident area is used as a reference. It can be easily obtained experimentally from the relationship of the light intensity distribution.
The widths of the effective incident area and the invalid incident area need not be limited to be larger than ½ of the width of the lens, and are determined by the actual light quantity distribution for irradiating the light incident surface of the polarization conversion element array. It

D. Projection Display Device: FIG. 13 is a schematic configuration diagram showing a main part of a projection display device 800 including the polarized illumination device 50 shown in FIG. This projection display device 800 includes a polarized illumination device 50, dichroic mirrors 801, 804, and reflection mirrors 802, 8
07,809 and relay lenses 806,808,810
And three liquid crystal light valves 803, 805, 811
A cross dichroic prism 813 and a projection lens 814.

The dichroic mirrors 801, 804 are
It has a function as a color light separation means for separating a white light flux 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 modulator that modulates the three color lights in accordance with the given image information (image signal) to form an image. The cross dichroic prism 813 has a function as a color light combining unit that combines color lights of three colors to form a color image.
The projection lens 814 has a function as a projection optical system that projects light representing the combined color image on the screen 815.

Blue light / green light reflection dichroic mirror 801
Transmits the red light component of the white light flux emitted from the polarized illumination 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
06, a relay lens 808, and a light guide unit 850 including a relay lens system including an emission lens 810 are provided. That is, the blue light is first transmitted through the green light reflecting dichroic mirror 804, and then first, the incident lens 8
06 and a reflection mirror 807, and then a relay lens 808.
Be led to. Further, the light is reflected by the reflection mirror 809, guided to the emission lens 810, and reaches the blue light liquid crystal light valve 811. In addition, three liquid crystal light valves 80
3, 805 and 811 correspond to the illumination area 80 in FIG. 7.

Three liquid crystal light valves 803, 805,
The reference numeral 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. On 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 combined by these dielectric multilayer films,
Light representing a color image is formed. The combined light is projected onto the screen 8 by a projection lens 814 which is a projection optical system.
The image is projected on 15 and the image is enlarged and displayed.

In this projection type 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 the light modulating means.
05,811 is used. In these liquid crystal light valves, polarizing plates (not shown) are usually attached to the entrance side and the exit side, respectively. 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 fluxes incident on the optical element 300, the light fluxes condensed by the condenser lens array 310 and applied to the polarization separation film 331 are all converted into s-polarized light as shown in FIG. 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 fluxes incident on the optical element 300, the light fluxes which have not been completely condensed by the condenser lens array 310 and have been applied to the reflection film 332 are converted into p-polarized light as described in the conventional technique. And emitted. Liquid crystal light valve 8
Illuminate 03,805,811. However, as described above, the incident surfaces of the liquid crystal light valves 803, 805, and 811 are provided with the polarizing plate so as to use only the s-polarized light and block the p-polarized light, as described above. On the other hand, the light 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.
Illuminate 5,811. Since this illumination light is white light including the s-polarized light component that can be used in the liquid crystal light valves 803, 805, 811, the liquid crystal light valves 803, 80
It is possible to use only the s-polarized light component of the light irradiated to 5,811. Therefore, since the projection display apparatus 800 shown in FIG. 13 uses the polarized illumination device 50 using the optical element 300 according to the embodiment, it has an advantage that the light utilization efficiency is higher than the conventional one.

As described above, by using the optical element according to this embodiment, it is possible to improve the light utilization efficiency in the projection display device as compared with the conventional one. Therefore, the image projected on the screen 815 can be made brighter.

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

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a main part of a polarized illumination device 50 to which an embodiment of the present invention is applied, 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 a 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.

6 is a cross-sectional view taken along the line A-A ′ of FIG.

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 polarization conversion element arrays 320a and 320b.

FIG. 9 is an explanatory diagram showing a manufacturing example of a polarization beam splitter array 340.

FIG. 10 is a partially enlarged view of the A-A ′ cross section shown in FIG. 5.

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

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

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

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

[Explanation of symbols]

10 ... Lens array 20 ... Polarizing beam splitter array 30 ... Polarizing beam splitter 36 ... Polarization separation film 40 ... Prism 46 ... Reflective film 50 ... Polarized illumination device 60 ... Light source section 70 ... Polarization generator 80 ... Illumination area 90 ... Illumination area 101 ... Light source lamp 102 ... Parabolic reflector 200 ... First optical element 201 ... Beam splitting lens 202 ... Intermediate luminous flux 300 ... Optical element 310 ... Condensing lens array 311 ... Condensing lens 311c ... center 320a, 320b ... Polarization conversion element array 321, 322, 322b, 322c ... Translucent member 323 ... Translucent member (plate glass) 325 ... Adhesive 331 ... Polarization separation film 332 ... Reflective film 340 ... Polarizing beam splitter array 350 ... Polarization conversion element 350a ... Polarization conversion element 350b ... Polarization conversion element 360 ... Translucent part 370 ... Dummy part 371 ... end face 372 ... Edge 375 ... Adhesive 376 ... Adhesive protrusion 381 ... λ / 2 retardation plate 390 ... Emitting lens 400 ... Second optical element 800 ... Projection display device 801, 804 ... Dichroic mirror 802, 807, 809 ... Reflective mirror 803, 805, 811 ... Liquid crystal light valve 806 ... Incident lens 807 ... Reflective mirror 808 ... Relay lens 809 ... Reflective mirror 810 ... Emitting lens 813 ... Cross dichroic prism 814 ... Projection lens 815 ... Screen 850 ... Light guide means CL ... Center of lens lateral direction Cp ... interval EA ... Effective incident area EA1, EA2, EA3, EA4 ... Effective incident area Gp ... gap Ia, Ib, Ic, Id ... Light intensity Lex1 ... luminous flux Lex2 ... luminous flux L1 ... Luminous flux L2 ... Luminous flux L3 ... Luminous flux La, Lb, Lc, Ld ... Lens Pa, Pb, Pc, Pd ... Light intensity distribution UA ... Invalid incident area UA1, UA2, UA3, UA4 ... Invalid incident area

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-10-177151 (JP, A) JP-A-7-43508 (JP, A) JP-A-2-167502 (JP, A) JP-A-8- 114765 (JP, A) JP-A-8-304739 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B 27/28 G02B 5/30

Claims (4)

(57) [Claims] 1. A method of manufacturing an optical element, comprising: (a) a first translucent member having a polarization separation film and a reflection film formed thereon, and the polarization separation film and the reflection film formed thereon. A plurality of second light-transmissive members, which are not laminated, are alternately laminated, the polarization separation film and the reflection film are not formed at the beginning and the end of the lamination, and the second light-transmissive member is not formed. A step of forming a block by adhering a third translucent member having a different thickness to the member, and (b) cutting the block at a predetermined angle to form a substantially parallel light incident surface and light emitting surface. Forming a translucent block having (c) attaching a lens array to the surface of the translucent block.
A method of manufacturing an optical element, comprising: 2. A method of manufacturing an optical element, comprising: (a) a first light-transmissive member having a polarization separation film and a reflection film formed thereon, and the polarization separation film and the reflection film formed thereon. A plurality of second light-transmissive members, which are not laminated, are alternately laminated, the polarization separation film and the reflection film are not formed at the beginning and the end of the lamination, and the second light-transmissive member is not formed. A step of forming a block by adhering a third translucent member having a different thickness to the member, and (b) cutting the block at a predetermined angle to form a substantially parallel light incident surface and light emitting surface. Forming a light-transmitting block having (c) a plurality of the light-transmitting blocks, and
Attach to the lens array with the membranes facing each other
And a step of producing the optical element. 3. The method of manufacturing an optical element according to claim 1 , further comprising: before the step (c), the light entrance surface and the light exit surface of the translucent block. And a step of polishing the optical element. 4. The optical element according to claim 1 , wherein the third translucent member is the first translucent member and the first translucent member. 2. A method for manufacturing an optical element, which is thicker than the translucent member of 2.