Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2002-03-26
2003-12-30
Gray, Linda (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S106000, C156S154000, C156S267000, C156S256000, C359S485050, C359S487030, C359S490020, C359S490020, C359S385000, C359S389000, C359S360000
Reexamination Certificate
active
06669797
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a manufacturing method for a polarizing conversion element for converting incident non-polarized light into specified polarized light.
2. Description of Related Art
In a projector, a light-modulating device for modulating light corresponding to image signals is used. As the light-modulating device, the type of using only one type of linear polarized light, such as a transmissive liquid crystal panel and a reflective liquid crystal panel, is usually used. In the projector which only uses such one type of linear polarized light, a polarizing conversion element for converting emitted non-polarized light from a light source into one type of a linear polarized light component (S-polarized light component or P-polarized light component, for example) is provided.
FIGS.
8
(A)-(B) are schematic representations showing a polarizing conversion element
320
. FIG.
8
(A) shows the polarizing conversion element
320
in the x-z plane, while FIG.
8
(A) shows the polarizing conversion element
320
in the x-y plane.
The polarizing conversion element
320
may consist of a polarizing beam splitter array (polarized light separating element)
340
and a plurality of &lgr;/2 phase films
381
selectively arranged on portions of emitting surface of the polarizing beam splitter array
340
. The polarizing beam splitter array
340
has a height of h and a shape in which a plurality of column-shaped light transmissive members
324
, each having a parallelogram cross-section, are sequentially bonded to each other, and column-shaped light transmissive members
325
and
326
, each having a trapezoidal cross-section, are respectively bonded to the two ends of the bonded members
324
. Polarization separating films
331
and reflecting films
332
are alternately formed on each of boundary surfaces between light transmissive members
324
,
325
, and
326
. The &lgr;/2 phase films
381
are selectively arranged at mapping portions in the x-direction of emitting light from the polarization separating film
331
or the reflecting film
332
. In this example, the &lgr;/2 phase films
381
are selectively arranged at mapping portions in the x-direction of emitting light from the polarization separating film
331
.
The polarizing conversion element
320
separates incident light on the polarization separating film
331
into an S-polarized light component and a P-polarized light component. The S-polarized light is reflected by the polarization separating film
331
and is further reflected by the reflecting film
332
to be emitted therefrom. On the other hand, the P-polarized light component is allowed to pass through the polarization separating film
331
just as it is. On the emitting surface of the transmitted light from the polarization separating film
331
, the &lgr;/2 phase film
381
is arranged, whereby the P-polarized light component is transformed to the S-polarized light component to be emitted therefrom. Therefore, a set of the polarization separating film
331
, the reflecting film
332
, and the &lgr;/2 phase film
381
, which adjoin each other, corresponds to one polarizing conversion unit. In addition, the polarizing conversion element
320
in this example has three lines of polarizing conversion unit
350
and one line of dummy unit
350
d.
In such a manner, the polarizing conversion element
320
is an optical element for converting incident light on the polarization separating film
331
into substantially one kind of a linearly polarized light component.
SUMMARY OF THE INVENTION
FIG. 9
is a schematic representation showing a manufacturing example for the polarizing beam splitter array
340
. In the polarizing beam splitter array
340
, for example, a first glass plate
321
having the polarization separating film
331
and the reflecting film
332
formed thereon and a second glass plate
322
having no film formed thereon are alternately bonded to each other by an optical adhesive
327
, so that the polarization separating film
331
and the reflecting film
332
are alternately arranged. Then, an ultra violet ray (UV ray) is irradiated thereon to cure the optical adhesive
327
. At this time, third glass plates
323
having a different thickness from that of the first and the second glass plates
321
and
322
are used as first and the last plates of the bonded plates, to form a composite plate member
400
. Light transmissive blocks are cut substantially in parallel with each other off the composite plate member
400
formed as above along sections (shown by broken lines in the drawing) inclining at the predetermined angle “&thgr;” with the surface of the composite plate member
400
, using a multi-wire saw or a multi-blade saw. The value “&thgr;” is preferably about 45°. Here, “the surface of the composite plate member
400
” indicates the surface of the third plates
323
bonded at the both ends. Protruding portions of both ends of the block are cut off by a dicing saw or a laser cutting apparatus so that the block has a substantially rectangular shape. Surfaces (cutting sections) of the light transmissive block cut in such a manner are polished to obtain the polarizing beam splitter array
340
(FIGS.
8
(A)-(B)). In addition, portions formed by the first and the second glass plates
321
and
322
correspond to the light transmissive members
324
, while one of the portions formed by the third glass plates
323
at one of the two ends corresponds to the light transmissive member
325
, and the other thereof at the other end corresponds to the light transmissive member
326
. The thickness of the third glass plate
323
corresponding to the light transmissive members
325
may be different from that of the third glass plate
323
corresponding to the light transmissive members
326
.
In addition, the polarizing beam splitter array may be referred to as “a light transmissive block” below.
Conventionally, the polarizing conversion element has been manufactured in the manner described above to improve efficiency. However, a further improvement in manufacturing efficiency is desirable.
The present invention is made to at least solve the above-mentioned problems, and it is an object of the present invention to at least provide a technology to manufacture a polarizing conversion element more efficiently.
Accordingly, a first method for manufacturing a polarizing conversion element according to the present invention may consist of the steps of:
preparing k sets of light transmissive members, k being an integer of 2 or greater, where each of the sets may consist of a plurality of first light transmissive plates and a plurality of second light transmissive plates having substantially a same thickness as that of the first light transmissive plates;
preparing (K+1) third light transmissive plates having a greater thickness than those of the first light transmissive plates and the second light transmissive plates;
producing a composite plate member by alternately arranging and bonding one set of the plurality of first light transmissive plates and the plurality of second light transmissive plates to each of spaces between the (K+1) third light transmissive plates, and alternately arranging a plurality of polarization separating films and a plurality of reflecting films on each interface between the first light transmissive plates, the second light transmissive plates and third light transmissive plates in the composite plate member;
producing a block substrate having a light receiving surface and a light emitting surface by cutting the composite plate member along a first section parallel to a surface inclining at a predetermined angle with a surface of the composite plate member, the light receiving surface and the light emitting surface being in parallel to the first section;
polishing the light receiving surface and the light emitting surface of the block substrate; and
producing k light transmissive blocks from the one block substrate by dividing the block substrate at positions of the thir
Gray Linda
Seiko Epson Corporation
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