U.S. patent application number 09/904561 was filed with the patent office on 2001-12-27 for planar type lens manufacturing method.
Invention is credited to Ito, Tomotaka, Watanabe, Hidetoshi.
Application Number | 20010054478 09/904561 |
Document ID | / |
Family ID | 17778918 |
Filed Date | 2001-12-27 |
United States Patent
Application |
20010054478 |
Kind Code |
A1 |
Watanabe, Hidetoshi ; et
al. |
December 27, 2001 |
Planar type lens manufacturing method
Abstract
A sure and efficient manufacturing method of a translucent type
screen using micro glass beadsis probided. A carbon toner is
scattered onto micro glass beads which are buried and fixed in a UV
curable resin layer, and the carbon toner is uniformly filled in
the gaps between the micro glass beads by a rotating brush or a
press roll or the like. The supply and filling of the carbon toner
may be simultaneously performed by an air jet nozzle. Subsequently,
an extra fine fiber cloth, sticky tape, sticky roll or the like is
continuously brought into contact with the upper surface of the
carbon toner to remove the carbon toner at the light emission
portion of the micro glass beads.
Inventors: |
Watanabe, Hidetoshi; (Chiba,
JP) ; Ito, Tomotaka; (Kanagawa, JP) |
Correspondence
Address: |
Ronald P. Kananen
RADER, FISHMAN & GRAUER, PLLC
Suite 501
1233 20th Street, N.W.
Washington
DC
20036
US
|
Family ID: |
17778918 |
Appl. No.: |
09/904561 |
Filed: |
July 16, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09904561 |
Jul 16, 2001 |
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09177799 |
Oct 23, 1998 |
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6261402 |
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Current U.S.
Class: |
156/241 ;
156/276 |
Current CPC
Class: |
B29D 11/00 20130101;
B29C 70/64 20130101; Y10T 428/24372 20150115; Y10T 428/24926
20150115 |
Class at
Publication: |
156/241 ;
156/276 |
International
Class: |
B44C 001/165 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 24, 1997 |
JP |
P09-292207 |
Claims
What is claimed is:
1. A planar type lens manufacturing method comprising: a step of
forming a transparent sticky layer on a transparent base; a step of
supplying plural transparent fine spheres onto said transparent
sticky layer; a step of burying said plural transparent fine
spheres in said transparent sticky layer in a depth which is
substantially equal to the half of the diameter thereof; a step of
supplying colored material so that said colored material is filled
in at least the gaps between said plural transparent fine spheres;
and a step of removing said colored material located at at least
light-transmissible positions of the opposite side to said
transparent base.
2. The planar type lens manufacturing method as claimed in claim 1,
wherein carbon toner is used as said colored material.
3. The planar type lens manufacturing method as claimed in claim 2,
wherein said carbon toner using cellulose acetate as binder is
used.
4. The planar type lens manufacturing method as claimed in claim 2,
wherein said carbon toner has a particle diameter of 0.05 to 15
.mu.m.
5. The planar type lens manufacturing method as claimed in claim 4,
wherein in said step of supplying said colored material, after
carbon toner having a relatively large particle size is supplied,
carbon toner having a small particle size is supplied between the
carbon toner having the relatively large particle size.
6. The planar type lens manufacturing method as claimed in claim 2,
wherein in said step of supplying said colored material, after said
carbon toner is scattered, said carbon toner is buried in the gaps
between said plural transparent fine spheres by a rotating
brush.
7. The planar tape lens manufacturing method as claimed in claim 2,
wherein in said step of supplying said colored material, after said
carbon toner is scattered, said carbon toner is buried in the gaps
between said plural transparent fine spheres by a pressure
roller.
8. The planar type lens manufacturing method as claimed in claim 2,
wherein in said step of supplying said colored material, said
carbon toner is sprayed by an air jet nozzle to be buried into the
gaps between said plural transparent fine spheres.
9. The planar type lens manufacturing method as claimed in claim 2,
wherein in said step of removing said colored material, said
colored material is removed by making said carbon toner adhere to
extra fine fiber cloth.
10. The planar type lens manufacturing method as in claim 2,
wherein in said step of removing said material, said colored
material is removed by making said carbon toner adhere to an
adhesive roll.
11. The planar type lens manufacturing method as claimed in claim
2, wherein in said step of removing said colored material, said
colored material is removed by making said carbon toner adhere to
an adhesive plane of an adhesive tape.
12. The planar type lens manufacturing method as claimed in claim
1, further comprising a step of laminating a second transparent
base through a second transparent sticky layer on said plural
transparent fine spheres after said step of removing said colored
material.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a method of manufacturing a
planar type lens which is suitably used for a screen for a back
projection type projector, for example.
[0002] Recently, a back projection type projector using a liquid
crystal light valve or a CRT has been actively developed as a
large-screen display for HDTV (Hi-vision), a theater or the
like.
[0003] FIG. 1 schematically shows the construction of a
conventional back projection type projector.
[0004] A box type projector is illustrated as an example.
Projection picture light L from a picture projection unit 101, for
example, is reflected by a reflection mirror 102 and guided to a
translucent type screen 105. The translucent type screen 105
comprises a Fresnel lens 103, and a lenticular lens 104 which
normally extends in the vertical direction. The projection picture
light L which is incident from the back surface of the translucent
type screen 105 is set to substantially parallel light by the
Fresnel lens 103, and then diffused mainly in the horizontal
direction by the lenticular lens 104.
[0005] As shown in FIGS. 2A and 2B, the lenticular lens 104 is
provided with projecting portions 104a extending in the vertical
direction at the back side (light emission side), and black stripes
104b which absorb external light to enhance the screen contrast are
provided to the projecting portions 104a. For example, after
acrylic resin is subjected to extrusion molding to have the shape
of the lenticular lens 104 containing the projecting portions 104a,
and then only the projecting portions 104a are subjected to black
print to form the back stripes 104b.
[0006] As shown in FIG. 2B, the width w of the black stripes 104b
is normally set to be 0.3 to 0.4 time of the pitch p of the
lenticular lens 104.
[0007] However, in the translucent type screen using the lenticular
lens as described above, a wide angle of visibility can be obtained
in the horizontal direction because the light is widely diffused in
the horizontal direction. However, it has a disadvantage that the
angle of visibility is small in the vertical direction because the
light is diffused in only the narrow range in the vertical
direction. In order to overcome this disadvantage, a structure
having a combination of a lenticular lens extending in the vertical
direction and a lenticular lens extending in the horizontal
direction is known, however, it has a problem that the part cost
and the manufacturing cost rise up because of the number of parts
is increased. Further, there is a problem that the thickness of the
screen is increased and the weight of the screen is increased
because the lamination number of the screen is increased, and also
the effect of the multiple reflection between respective layers is
intensified.
[0008] Further, as described above, when the black stripes are
provided to enhance the contrast, it is necessary that the
projecting portions for black print are provided at the light
emission side of the lenticular lens, and in addition it is
necessary that the projecting portions are designed to have such a
width that they do not obstruct the emission light. Therefore, the
area rate of the external light absorption portion based on the
black stripes is normally limited to about 30 to 40%. Therefore,
the effect of enhancing the contrast is relatively low.
[0009] Therefore, in place of the lenticular lens, much attention
has been paid to a translucent screen based on a planar type lens
which is constructed by two-dimensionally arranging transparent
fine spheres (see U.S. Pat. No. 2,378,252, U.S. Pat. No. 3,552,822,
Japanese Utility Model Registration No. 2513508, for example, and
studies and developments thereof have been performed to practically
use the translucent screen for a large-screen high-definition
display.
[0010] The construction which was previously proposed by the
applicant of this application in Japanese Unexamined Patent
Application No. Hei-9-100590 (filed, Apr. 17, 1997) will be
described with reference to FIGS. 3 to 5, for example.
[0011] FIG. 3 shows the main construction of a back projection type
projector of open type. Projection picture light L from a picture
projection unit 21 is diffused forwardly through a translucent type
screen 10 comprising a Fresnel lens 22 and a planar type lens 23.
The planar type lens 23 is constructed by two-dimensionally
arranging transparent fine spheres 2 such as glass beads in a
closest packed structure. Accordingly, the projection picture light
L can be diffused in a wide range in each of the horizontal and
vertical directions by one layer comprising the transparent fine
spheres 2.
[0012] FIG. 4 shows a back projection type projector of box type,
and projection picture light L from a picture projection portion 21
disposed in a housing 25 is reflected by a reflection mirror 24,
and diffused forwardly through a translucent screen 10 comprising a
Fresnel lens 22 and a planar type lens 23 comprising transparent
fine spheres 2.
[0013] FIG. 5 shows a planar type lens having the most basic
construction in ones described in the above application.
[0014] In the planar type lens 23 having the most basic
construction, the many transparent fine spheres 2 such as glass
beads adhere onto a transparent substrate 1 such as a glass plate
or the like through a colored layer (light absorption layer) having
a sticky or adhesive function. Each transparent fine sphere 2 is
buried in the colored layer 3 so as to be exposed from the colored
layer 3 at the light incident side by about 50% of its diameter,
and brought into contact with the transparent substrate 1 at the
light emission side thereof.
[0015] The incident light L.sub.in which is incident through the
Fresnel lens (not shown) is converged by each transparent fine
sphere 2 as shown in the figure, transmitted in the neighborhood of
the contact portion between each transparent fine sphere 2 and the
transparent substrate 1, diffused and emitted. L.sub.out represents
emitted light. On the other hand, most of external light L.sub.ax
which is incident from the transparent substrate 1 side is absorbed
by the colored layer 3, and thus reduction in contrast due to
reflection of the external light L.sub.ax is suppressed.
[0016] At this time, in the planar type lens 23, the area rate of
the light absorption layer at the light emission side by the
colored layer 3 can be set to about 80% or more, for example.
Accordingly, the reduction in contrast due to the reflection of the
external light L.sub.ax can be greatly suppressed, and thus there
can be implemented a screen which is hardly affected by the
external light and has high contrast.
[0017] In the above application, the planar type lens 23 is
manufactured as follows.
[0018] That is, first, the colored layer 3 serving as a sticky or
adhesive layer is formed on the transparent substrate 1, and many
transparent fine spheres 2 are scattered onto the colored layer 3.
Thereafter, the transparent fine spheres 2 are pressed from the
upper side thereof so as to be pushed into the colored layer 3.
[0019] According to such a method, however, when the transparent
fine spheres 2 are pressed from the upper side thereof, the
transparent fine spheres 2 are rotated, and thus the colored layer
3 adheres to the surface of the exposed portion, thereby inducing
reduction in transmittance, thus reduction in brightness of the
screen is induced.
[0020] Further, there are some portions where the colored layer 3
remains at a thickness of about several .mu.m between the
transparent fine spheres 2 and the transparent substrate 1, so that
the reduction of the transmittance, and thus the reduction in
brightness of the screen is induced.
[0021] Further, it is normally needed to increase the temperature
in order to reduce the viscosity of the colored layer 3 when the
transparent fine spheres 2 are pushed in, and thus relatively
large-scale facilities are needed to increase the temperature and
cool. Further, occurrence of warpage of the transparent substrate 1
due to heat is a problem which cannot be neglected particularly for
the large-screen display.
SUMMARY OF THE INVENTION
[0022] Therefore, an object of the present invention is to provide
a planar type lens manufacturing method which can manufacture a
planar type lens comprising transparent fine spheres without
reducing the transmittance thereof and with no occurrence of
warpage.
[0023] In order to achieve the above-described object, the planar
type lens manufacturing method according to the present invention
comprises: a step of forming a transparent sticky layer on a
transparent base; a step of supplying plural transparent fine
spheres onto the transparent sticky layer; a step of burying the
plural transparent fine spheres in the transparent sticky layer in
a depth which is substantially equal to the half of the diameter
thereof; a step of supplying colored material so that the colored
material is filled in at least the gaps between the plural
transparent fine spheres, and a step of removing the colored
material located at at least light-transmissible positions of the
opposite side to the transparent base.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a schematic diagram showing a conventional back
projection type projector;
[0025]
[0026] FIGS. 2A and 2B each is a schematic diagram and a
cross-sectional view showing the construction of a lenticular lens
in the conventional back projection type projector;
[0027] FIG. 3 is a schematic diagram showing a back projection type
projector of open type using the planar type lens based on the
transparent fine spheres;
[0028] FIG. 4 is a schematic diagram showing a back projection
projector of box type using the planar type lens based on the
transparent fine spheres;
[0029] FIG. 5 is a cross-sectional view showing the basic
construction of the planar type lens based on the transparent fine
spheres;
[0030] FIGS. 6A and 6B each is a cross-sectional view showing the
most basic construction of a planar type lens manufactured by a
manufacturing method according to the present invention;
[0031] FIGS. 7A and 7B each is a cross-sectional showing the
practical construction of the planar type lens manufactured by the
manufacturing method according to the present invention;
[0032] FIGS. 8A to 8C each is a graph showing a light beam tracking
and a simulation result of a screen gain in the planar type lens
manufactured by the manufacturing method according to the present
invention;
[0033] FIGS. 9A and 9D each is a cross-sectional view showing the
manufacturing method of the planar type lens according to an
embodiment of the present invention in step order;
[0034] FIG. 10 is sketch diagrams based on optical microscope
photographs in a state where transparent fine spheres are arranged
and in a state where a light emission portion is formed in the
colored layer, respectively;
[0035] FIGS. 11A to 11D each is a cross-sectional view showing the
manufacturing method of the planar type lens of the embodiment of
the present invention in step order;
[0036] FIGS. 12A and 12B each is a cross-sectional view showing the
manufacturing method of the planar type lens according to the
embodiment of the present invention in step order;
[0037] FIGS. 13A to 13E each is a cross-sectional view showing the
construction of a brush used in a toner filling step of the
manufacturing method of the planar type lens according to the
present invention;
[0038] FIG. 14 is a cross-sectional view showing a toner removing
step of the manufacturing method of the planar type lens of the
present invention;
[0039] FIG. 15 is a cross-sectional view showing another embodiment
of the toner removing step of the manufacturing method of the
planar type lens according to the present invention;
[0040] FIG. 16 is a cross-sectional view showing another embodiment
of the toner removing step of the manufacturing method of the
planar type lens according to the present invention;
[0041] FIG. 17 is a cross-sectional view showing another embodiment
of the toner removing step of the manufacturing method of the
planar type lens according to the present invention;
[0042] FIGS. 18A to 18D each is a cross-sectional view showing the
manufacturing method of the planar type lens according to another
embodiment of the present invention in step order;
[0043] FIGS. 19A to 19C each is a cross-sectional view showing the
manufacturing method of the planar type lens according to another
embodiment of the present invention;
[0044] FIG. 20 is a cross-sectional view showing the construction
of the planar type lens manufactured by the manufacturing method
according to the present invention;
[0045] FIG. 21 is a cross-sectional view showing the construction
of the planar type lens manufactured by the manufacturing method
according to the present invention;
[0046] FIG. 22 is a cross-sectional view showing the construction
of the planar type lens manufactured by the manufacturing method
according to the present invention;
[0047] FIG. 23 is a cross-sectional view showing the construction
of the planar type lens manufactured by the manufacturing method
according to the present invention;
[0048] FIG. 24 is a cross-sectional view showing the construction
of the planar type lens manufactured by the manufacturing method
according to the present invention;
[0049] FIG. 25 is a cross-sectional view showing the construction
of the planar type lens manufactured by the manufacturing method
according to the present invention;
[0050] FIG. 26 is a sketch diagram based on an electron microscope
photograph of carbon toner of 0.05 to 0.2 .mu.m in particle
size;
[0051] FIG. 27 is a sketch diagram based on an electron microscope
photograph of carbon toner of 2 to 15 .mu.m in particle size;
and
[0052] FIG. 28 is a cross-sectional view showing the construction
of the planar type lens manufactured by the manufacturing method
according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0053] A preferred embodiment according to the present invention
will be described.
[0054] In the following embodiment, the portions corresponding to
the construction described with reference to FIGS. 3 to 5 are
represented by the same reference numerals.
[0055] FIG. 6 schematically shows the most basic construction of a
planar type lens manufactured by a manufacturing method according
to the present invention.
[0056] As shown in FIG. 6A, in the planar type lens 23, a
transparent base 4 having rigidity or flexibility which is formed
of a glass plate, a plastic plate or the like, for example, is
provided at the light incident side.
[0057] The base material 4, a sticky layer 5, fine spheres 2
described later, etc. are not necessarily required to be perfectly
transparent insofar as most of targeted light can be transmitted
therethrough, and thus in this specification, the term
"transparent" is used as containing the degree of transparency
which is extended to semi-transparency.
[0058] A transparent sticky layer 5 having a sticky and adhesive
function such as UV (ultraviolet) curing resin or the like is
provided on the surface of the light emission side of the
transparent base 4, and many transparent fine spheres 2 formed of
glass beads or the like are buried and held in the transparent
sticky layer 5. Further, a colored (black) layer 3 for external
light absorption which is formed of carbon toner or the like is
filled in the gaps between these transparent fine spheres 2 at the
light emission side.
[0059] As is clearly shown in FIG. 6B with being enlarged, each
transparent fine sphere 2 is buried in the transparent sticky layer
5 by about a half of the diameter thereof (for example, d=50 .mu.m)
at the light incident side. On the other hand, at the light
emission side, each transparent fine sphere 2 is exposed from the
colored layer 3 by a predetermined thickness (for example, t=2.5
.mu.m) to form a light emission portion having a predetermined
diameter (for example, s=21.6 .mu.m).
[0060] FIG. 7 shows a more practical structure of the planar type
lens 23.
[0061] In this structure, as shown in FIG. 7A, in the basis
structure shown in FIG. 6, a transparent base 1 is also laminated
through a transparent sticky layer 6 at the light emission side.
These transparent sticky layer 6 and transparent base 1 may be
formed of the same materials as the transparent sticky layer 5 and
the transparent base 4 at the light incident side.
[0062] By the structure of sandwiching the transparent fine spheres
2 from both the sides thereof, enhancement of the holding strength
of the transparent fine spheres 2 and protection of the transparent
fine spheres 2 and the colored layer 3 from the outside can be
achieved.
[0063] FIG. 7B schematically shows the operation of the planar type
lens 23.
[0064] The incident ling L.sub.in which is set to substantially
parallel light is incident through the transparent base 4 and the
transparent sticky layer 5 at the light incident side into each
transparent fine sphere 2, and light which are converged by these
fine spheres 2 is passed through the transparent sticky layer 6 and
the transparent base 1 at the light emission side and diffused and
emitted forwardly as emission light L.sub.out.
[0065] At this time, many incident light beams L.sub.in are
incident to the respective transparent fine spheres 2 because each
transparent fine sphere 2 is buried in the transparent sticky layer
5 by about a half of the diameter thereof. On the other hand, at
the light emission side, only the limited area through which light
passes is exposed from the colored layer 3. Accordingly, in the
planar type lens 23, the area rate of the colored layer 3 at the
light emission side can be increased while the light transmission
amount, that is, the brightness in the translucent type screen is
set to be high, so that the reduction or the contrast due to
reduction of external light can be greatly suppressed.
[0066] FIG. 8 shows results when a light beam tracking and a
simulation of a screen gain in the planar type lens 23 having the
construction shown in FIG. 7 were performed.
[0067] The calculation was made on the condition that the
transparent base 4, 1 was formed of polymethyl methacrylate (PMMA)
of refractivity n=1.490 the transparent sticky layer 5, 6 was
formed of acrylic UV curing resin of refractivity n=1.490, and the
transparent fine spheres 2 were formed of glass beads having
refractivity n=1.900. The refractivity of air n=1.000.
[0068] The thickness of each layer was set to 100 .mu.m for the
transparent base 4, 1, 30 .mu.m for the transparent sticky layer 5,
25 .mu.m for the colored layer 3 of carbon toner, and 5 .mu.m for
the transparent sticky layer 6, and the transparent fine spheres 2
were constructed so that the diameter thereof was set to 50 .mu.m
and they were buried into the transparent sticky layer 5 by a half
of the diameter, 25 .mu.m. The transmittance of all the layers,
except for the colored layer 3, was set to 100%.
[0069] As shown in FIG. 8A and FIG. 8B which is an enlarged view of
FIG. 8A, the light emission portion of the transparent fine sphere
2 has an area, and in this case, it is a circle of about 10.8 .mu.m
in radius. Accordingly, it is apparent as shown in FIG. 6B that the
optical loss can be minimized by exposing from the colored layer 3
a portion having a diameter s=21.6 .mu.m or more of each
transparent fine sphere 2. In order to expose from the colored
layer 3 the portion having the diameter s=21.6 .mu.m or more, it is
necessary to remove the portion of the colored layer 3 which is
located in the depth t=2.5 .mu.m or more from the top of each
transparent fine sphere 2.
[0070] Here, assuming that the plane filling rate of the
transparent fine sphere 2 is set to 90%, the area rate of the black
portion of the screen which is viewed from the light emission side
is represented by:
1-{0.9.times.(21.6/50.0).sup.2}=0.83.
[0071] and it is equal to about 83%. That is, for example, the
black portion area rate of the conventional translucent type screen
in which the black stripes are provided to the lenticular lens
shown in FIG. 2 is ordinarily limited to about 30 to 40%, however
the translucent type screen using the planar type lens 23 can
greatly increase the black portion area rate. Accordingly, a clear
image can be obtained while the reduction of contrast due to
reflection of external light is little.
[0072] FIG. 8B shows variation of the screen gain in the light
emission direction.
[0073] In the figure, the abscissa represents the emission angle
(degree) of emitted light, and the ordinate represents the screen
gain (=brightness in an emission angle direction/incident light
amount).
[0074] The total light beam transmittance of the planar type lens
(=total emission light amount/total incident light amount) was
equal to about 77.4%, the light beam transmittance at the portion
of the transparent fine sphere 2 (=total emission light
amount/incident light amount to transparent fine sphere 2=total
emission light amount/(total incident light amount.times.(area of
transparent fine sphere 2 in unit area/unit area))) was equal to
about 85.4%.
[0075] In the result of FIG. 8B, the peak gain at the center
portion was equal to about 2.21, the angle range in which the half
gain of the peak gain could be obtained was equal to about
53.0.degree., the angle range in which one-third gain could be
obtained was equal to about 71.9.degree., and the angle range in
which one-tenth gain could be obtained was equal to about
162.6.degree..
[0076] Next, a method of manufacturing the planar type lens
constructed shown in FIG. 7 will be described with reference to
FIGS. 6, 7, 9, 11 and 12.
[0077] First, as shown in FIG. 9A, the transparent sticky layer 5
formed of acrylic UV curable resin which promotes its bridging
reaction under UV cure, and also holds viscosity on the surface
thereof after the UV is coated at a thickness of about 20 to 30
.mu.m on the transparent base 4 formed of a glass plate or a
plastic plate of PMMA or the like.
[0078] Subsequently, as shown in FIG. 9B, many transparent fine
spheres 2 which are formed of micro glass beads of about 50 .mu.m
in average particle size (diameter) are fed onto the transparent
sticky layer 5 from a hopper (not shown) so that the transparent
fine spheres 2 are two-dimensionally arranged in the closest packed
structure in at least the lowermost layer (in FIG. 9B and next FIG.
9C, only the transparent fine spheres 2 in the lowermost layer are
illustrated).
[0079] Thereafter, as omitted from the illustration, the
transparent fine spheres 2 are squeezed to be made uniform in
height.
[0080] Subsequently, as shown in FIG. 9C, the transparent fine
spheres 2 are pressed from the upper side thereof by a press roller
31 so that the transparent fine spheres 2 in the lowermost layer
are buried into the transparent sticky layer 5 by about a half of
the diameter thereof (=25 .mu.m).
[0081] Thereafter, as omitted from the illustration, extra
transparent fine spheres 2 are removed by vacuum suction or the
like.
[0082] Subsequently, as shown in FIG. 9D, ultraviolet rays are
irradiated by an ultraviolet lamp 32 to cure the transparent sticky
layer 5 formed of UV curable resin and fix the transparent fine
spheres 2.
[0083] FIG. 10A is a sketch diagram based on an optical microscope
photograph of a planar type lens in a state that micro glass beads
are actually fixedly arranged.
[0084] Subsequently, as shown in FIG. 11A, carbon toner of fine
powder is supplied to the overall surface by the hopper 33 to form
the colored layer 3.
[0085] As the carbon toner is used ultra fine particles of 0.05 to
0.2 .mu.m in particle size in which carbon black is used as
coloring agent and cellulose acetate is used as binder.
[0086] Cellulose acetate has many hydroxyl groups, and has high
affinity to non-bridged UV curable resin. This means that it is
easily physically and chemically adsorbed to the surface of the
transparent sticky layer 5. Further, the ultra fine particles of
0.05 to 0.2 .mu.m in particle size are agglomerated through the
binder, however, the agglomeration state is easily deformed and
each particle is easily dispersed. Accordingly, these ultra fine
particles easily invades into the fine gaps like a string of beads.
With this property, the ultra fine particles are easily uniformly
filled in the gaps even in a closely packed state of the micro
beads.
[0087] As the carbon toner is known a heat fixing type using epoxy
resin as binder. The epoxy resin has strong affinity to the
surfaces of the glass beads, and thus since it is difficult to
afterwards remove the colored layer 3 of the light emission portion
of the transparent fine spheres 2 substantially perfectly, this
type of carbon toner is not so preferable.
[0088] Subsequently, as shown in FIG. 11B, the rotating brush 34 is
pushed against the colored layer 3 while being rotated, and the
rotating brush 34 is relatively moved in this state to uniformly
fill the carbon toner of the colored layer 3 into the gaps between
the transparent fine spheres 2 without unevenness.
[0089] FIG. 13 shows the construction of the rotating brush 34.
[0090] As shown in FIGS. 13A and 13B, the rotating brush 34 is
constructed by adhesively fixing a brush portion 34c to a rotating
disc 34b secured to a rotational shaft 34a, for example.
[0091] As shown in FIG. 13D, acrylic fiber having a diameter b=5 to
15 (.mu.m) is suitably used as the bristles 34d of the brush, and
as shown in FIG. 13C, and these bristles are cut out at a length
a=5 to 20 (mm) and implanted in the brush portion 34c. The length
of the bristles 34d is suitably selected in accordance with the
toner type, the status at the glass beads side, etc. The
implantation of the bristles 34d in the brush portion 34c may be
performed by implanting them closely and uniformly or by bundling
every several to several tens and implanting them at an equal
pitch. However, this may be suitably selected in accordance with
the toner type, the state at the glass beads side, etc.
[0092] For example, it may be adopted that toner is pushed into the
gaps between the transparent fine spheres 2 by long bristles 34d
and then short bristles 34d are lightly rubbed against the toner to
scrape off the toner on each transparent fine sphere 2 to some
extent, thereby facilitating a subsequent toner removing step.
[0093] FIG. 13E shows the brush portion 34c in which every several
to several tens bristles 34d of about c=5 (mm) in length are
bundled and implanted at an equal pitch.
[0094] As described above, the carbon toner of the colored layer 3
is filled into the gaps between the transparent fine spheres 2 with
evenness by the rotating brush 34, and then the carbon toner in an
area around the top portion of each transparent fine spheres 2 is
removed in the toner removing step shown in FIG. 11C, thereby
exposing the light emission portion of each transparent fine sphere
2 from the colored layer 3.
[0095] The toner removing step can be performed by continuously
bring extra fine fiber cloth (cloth woven of extra fine fiber of
about several .mu.m in diameter enlarged and as shown in FIG. 14.
For example, "Treshi" of Toray Industries, Inc., "Savina Minimax"
of Kanebo, Ltd. or the like) 35 in contact with the upper surface
of the colored layer 3 while it is moved relatively to the
transparent base 4, thereby trapping and accompanying the carbon
toner in the gaps between the fibers.
[0096] The extra fine fiber cloth 35 is used while the cloth which
is processed in a tape-shape is suspended around a mirror-surface
cylindrical guide 36 and made to continuously run, whereby the
contact portion of the cloth with the colored layer 3 is kept
planar under a fixed tension, and also a new fiber plane is brought
into contact with the colored layer 3 at any time. The extra fine
fiber cloth 35 may be designed in an endless structure and used
continuously to the extent that there occurs no trouble in toner
removing performance.
[0097] With respect to the extra fiber cloth 35 thus constructed
dust due to fall-out of fibers or the like is hard to occur, and it
is rare that toner powder trapped in the gaps between the fibers
gets out of the gaps and falls off. Therefore, it is very
convenient for the toner removing step.
[0098] In place of the extra fine fiber cloth 35, an adhesive tape
having weak adhesion or the like may be used.
[0099] FIG. 15 shows another embodiment of the toner removing
step.
[0100] In this embodiment, as shown in the figure, a sticky roll 38
is relatively moved to the transparent base 4 while being rotated,
and the sticky surface thereof is continuously brought into contact
with the colored layer 3, whereby the carbon toner of the colored
layer 3 is attached to the sticky surface of the sticky roll 38 to
be removed. The sticky surface of the sticky roll 38 is cleaned by
a cleaning mechanism 39, whereby a clean sticky surface is brought
into contact with the colored layer 3 at any time.
[0101] FIG. 16 shows another embodiment of the toner removing
step.
[0102] In this embodiment, as show in the figure, a rotating disc
40 to which extra fine fiber cloth 41 is attached is relatively
moved to the transparent base 4 while being rotated, and the carbon
toner of the colored layer 3 is adhesively attached to the extra
fine fiber cloth 41 to be removed. The same extra fine fiber cloth
35 as described with reference to FIG. 14 may be used as the extra
fine fiber cloth 41. The used extra fine fiber cloth 41 may be
exchanged integrally with the rotating disc 40.
[0103] FIG. 17 shows another embodiment of the toner removing
step.
[0104] In this embodiment, as shown in the figure, the sticky
surface 42a of the sticky tape 42 is continuously brought into
contact with the colored layer 3 to make the carbon toner adhere to
the sticky surface 42a, thereby removing the carbon toner. The
sticky tape 42 is suspended around a guide roller 43 and made to
continuously run, whereby the new sticky surface 42a of the sticky
tape 42 is brought into contact with the colored layer 3 at all
times, and the carbon toner is removed while the guide roller 43 is
relatively moved to the transparent base 4.
[0105] Through the above-described toner removing step, as shown in
FIG. 11D, the carbon toner located in the neighborhood of the top
portions of the transparent fine spheres 2 is removed, and the
light emission portion of each transparent fine sphere 2 is exposed
from the colored layer 3. FIG. 10B is a sketch diagram based on an
optical microscope photograph in this state. The planar type lens
23 having the basic construction shown in FIG. 6 is manufactured by
the steps until FIG. 11D.
[0106] Subsequently, as shown in FIG. 12A, the transparent base 1
coated with the transparent sticky layer 6 is laminated with no
entrance of bubbles therein while successively pressed from the end
thereof by a press roll 37. At this time, the transparent base 1 is
the same as the transparent base 4, and the transparent sticky
layer 6 is the same as the transparent sticky layer 5.
[0107] For example, when the transparent sticky layer 6 is formed
of the same UV curable resin as the transparent sticky layer 5, the
UV cure is performed after the above lamination step, thereby
enhancing the adhesive strength.
[0108] FIG. 18 shows a method of manufacturing a planar type lens
according to another embodiment.
[0109] In this embodiment, as shown in FIG. 18A, the carbon toner
of fine powder is supplied from the hopper 33 to form the colored
layer 3, and then as shown in FIG. 18B the colored layer 3 is
pressed from the upper side thereof by a press roll 44 of a silicon
rubber group to uniformly fill the carbon toner of the colored
layer 3 in the gaps between the transparent fine spheres 2.
Thereafter, as shown in FIG. 18C, the same toner removing step as
described with reference to FIGS. 14 to 17 is performed to remove
the carbon toner in the neighborhood of the top portion of each
transparent fine sphere 2 and expose the light emission portion of
each transparent fine sphere 2 from the colored layer 3, whereby
the structure shown in FIG. 18D is obtained.
[0110] FIG. 19 shows a method of manufacturing a planar type lens
according to another embodiment.
[0111] In this embodiment, as shown in FIG. 19A, toner powder is
jetted from an air jet nozzle 45 at a high speed, thereby
simultaneously performing the formation of the colored layer 3 and
the uniform filling of the carbon toner of the colored layer 3 into
the gaps between the transparent fine spheres 2. Thereafter, as
shown in FIG. 19B, the toner removing step is performed to remove
the carbon toner in the neighborhood of the top portion of each
transparent fine sphere 2, and to expose the light emission portion
of each transparent fine sphere 2 from the colored layer 3, thereby
obtaining the structure shown in FIG. 19C.
[0112] FIGS. 20 to 25 show various planar type lenses 23 which are
manufactured by the manufacturing method of the present
invention.
[0113] In an embodiment of FIG. 20, the transparent sticky layer 6
is directly coated and formed at the light emission side in the
most basic construction shown in FIG. 6 and the transparent base 1
constructed as shown in FIG. 7 is omitted. For example, when the
transparent sticky layer 6 is formed of UV curable resin, the
sufficient colored layer 3 and the protection of the transparent
fine spheres 2 can be achieved by performing the UV cure after the
coating of the transparent sticky layer 6.
[0114] In an embodiment of FIG. 21, the transparent base 1 is
directly laminated at the light emission side in the most basic
construction shown in FIG. 6, and the transparent sticky layer 6
constructed as shown in FIG. 7 is omitted. This structure is
applicable when the colored layer 3 itself has an adhesive
function, for example, when a mixture of carbon toner and
thermosetting adhesive is used.
[0115] In an embodiment of FIG. 22, an antireflection film 7 of
silicon oxide (SiO.sub.2) film or the like is provided at each of
the light incident side and the light emission side in the most
basic construction shown in FIG. 6. The antireflection film 7 may
be provided at only one of the light incident side and the light
emission side.
[0116] In an embodiment of FIG. 23, the antireflection film 7 is
provided at each of the light incident side and the light emission
side of the planar type lens 23 which is constructed as shown in
FIG. 20.
[0117] In an embodiment shown in FIG. 24, the antireflection film 7
is provided at each of the light incident side and the light
emission side of the planar type lens 23 constructed as shown in
FIG. 21.
[0118] In an embodiment shown in FIG. 25, the antireflection film 7
is provided at each of the light incident side and the light,
emission side of the planar type lens 23 constructed as shown in
FIG. 7.
[0119] According to the above-described manufacturing method, extra
fine particles of 0.05 to 0.2 .mu.m in particle size are used as
the carbon toner of the colored layer 3. FIG. 26 is a sketch
diagram based on an electron microscope photograph of the carbon
toner of extra fine particles. As described above, the carbon toner
of extra fine particles easily gets into fine gaps, and thus it is
easily uniformly filled in the gaps in which micro bead are closely
packed.
[0120] FIG. 27 is a sketch diagram based on an electron microscope
photograph of carbon toner of 2 to 15 .mu.m in particle size. In
this case, since the particle size of each particle is large, it is
difficult for the particles to enter the fine gaps, however, the
light absorption performance every particle is high and the light
shielding performance is excellent even when it forms a
monolayer.
[0121] Therefore, the carbon toner is classified as follows in
accordance with the particle size, for example:
1 Extra fine particle: particle size 0.05 to 0.2 .mu.m Fine
particle: particle size 0.2 to 2 .mu.m Normal particle: particle
size 2 to 15 .mu.m
[0122] It is preferable that these are suitably combined with each
other in conformity with the purpose and the process.
[0123] For example, as shown in FIG. 28, it is preferable that as
the colored layer 3 particles 3a of relatively-large size are first
supplied and then particles 3b of small size are supplied so as to
be filled in the large-size particles 3a. With this structure,
there can be formed the colored layer 3 which is excellent in both
the light shielding performance and the uniformity of the filling
into the gaps between the transparent fine spheres 2.
[0124] In the present invention, plural transparent fine spheres
are supplied onto the transparent sticky layer formed on the
transparent base, and these transparent fine spheres are buried
into the transparent sticky layer until the depth which is
substantially equal to about the half of the diameter thereof.
Thereafter, the colored material are supplied so as to be filled in
at least the gaps between the transparent fine spheres, and then
the colored material, for example, at the light emission position
of each transparent fine sphere is removed to manufacture the
planar type lens.
[0125] Accordingly, the light emission portion of each transparent
fine sphere can be surely formed, and for example, the planar type
lens which is suitably used for a translucent type screen and in
which reduction of contrast due to external light is little and the
transmittance of picture light is high can be manufactured with
high reproducibility and in low cost.
[0126] Further, no heat process is particularly required, and thus
warpage hardly occurs in the transparent base which is the
substrate for the planar type lens. Therefore, the present
invention is particularly convenient for a case where it is applied
to a large-scale projector screen.
[0127] Further, since carbon toner of relatively low cost can be
directly used as the colored layer, the cost can be more greatly
reduced as compared with the case where the carbon toner is used
while mixed with organic solvent or the like.
* * * * *