U.S. patent application number 10/981689 was filed with the patent office on 2006-03-02 for color wheel assembly with color wheel attached directly to driving motor.
This patent application is currently assigned to MINEBEA CO., LTD.. Invention is credited to Shigeyuki Adachi, Toshiaki Asakawa, Shinichi Niwa, Kuniyuki Takao.
Application Number | 20060044656 10/981689 |
Document ID | / |
Family ID | 35767976 |
Filed Date | 2006-03-02 |
United States Patent
Application |
20060044656 |
Kind Code |
A1 |
Niwa; Shinichi ; et
al. |
March 2, 2006 |
COLOR WHEEL ASSEMBLY WITH COLOR WHEEL ATTACHED DIRECTLY TO DRIVING
MOTOR
Abstract
A color wheel assembly includes a color wheel and a driving
motor. The color wheel is attached directly to a hub of the driving
motor. Consequently, no additional components are required to fix
the color wheel to the driving motor, thereby reducing the number
of components and the number of manufacturing processes. Thus, the
color wheel assembly as a time-share light dispersing device can be
inexpensively manufactured with a high degree of precision.
Inventors: |
Niwa; Shinichi; (Iwata-gun,
JP) ; Asakawa; Toshiaki; (Iwata-gun, JP) ;
Adachi; Shigeyuki; (Iwata-gun, JP) ; Takao;
Kuniyuki; (Iwata-gun, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
MINEBEA CO., LTD.
Kitasaku-gun
JP
|
Family ID: |
35767976 |
Appl. No.: |
10/981689 |
Filed: |
November 5, 2004 |
Current U.S.
Class: |
359/892 ;
359/889 |
Current CPC
Class: |
G02B 7/006 20130101;
G02B 26/008 20130101 |
Class at
Publication: |
359/892 ;
359/889 |
International
Class: |
G03B 21/14 20060101
G03B021/14 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 2, 2004 |
JP |
2004-255864 |
Claims
1. A color wheel assembly comprising: a driving motor including a
hub; and a color wheel including a plurality of filters that either
selectively transmit or selectively reflect lights having
respective wavelengths different from one another, the color wheel
being attached directly to the hub of the driving motor, wherein
the color wheel comprises a plurality of independent sectorial
color filter segments arranged on an outer surface of the hub of
the driving motor, the independent sectorial color filter segments
being independently arranged so as to form a disk.
2. (canceled)
3. A color wheel assembly according to claim 1, wherein the hub has
protrusions, and the sectorial color filter segments each have
either at least one through-hole or at least one cavity for
receiving each of the protrusions.
4. A color wheel assembly according to claim 3, wherein the
protrusions are each constituted by a pin which is press-fitted
into each of either through-holes or cavities formed at the
hub.
5. A color wheel assembly according to claim 3, wherein the
protrusions are each constituted by a pin which is loose-fitted in
each of either through-holes or cavities formed at the hub and is
adhesively fixed therein.
6. A color wheel assembly according to claim 3, wherein the
protrusions are each constituted by a ball which is press-fitted
into each of either through-holes or cavities formed at the
hub.
7. A color wheel assembly according to claim 3, wherein the
protrusions are each constituted by a ball which is loose-fitted in
each of a through-hole or a cavity formed on the outer surface of
the hub and is adhesively fixed therein.
8. A color wheel assembly according to claim 3, wherein the
protrusions are engagingly inserted through the through-holes of
the sectorial color filter segments, and through either the
through-holes or the cavities of the hub when the color wheel is
placed on the hub such that the through-holes of the sectorial
color filter segments coincide with either the through-holes or the
cavities of the hub.
9. A color wheel assembly according to claim 3, wherein the hub is
formed by one of casting and molding so as to integrally include
the protrusions.
10. A color wheel assembly according to claim 3, wherein the hub is
formed by pressing so as to integrally include the protrusions.
11. A color wheel assembly according to claim 7, wherein the cavity
is an annular groove, the annular groove being concentric with an
axis of rotation of a shaft of the motor.
12. A color wheel assembly according to claim 7, wherein the
cavities formed on the outer surface of the hub are arc-shaped
grooves being arranged so as to form a discontinuous annular groove
that is concentric with an axis of rotation of a shaft of the
motor.
13. A color wheel assembly according to claim 3, wherein the
protrusions are press-fitted into either the through-holes or the
cavities of the sectorial color filter segments.
14. A color wheel assembly according to claim 3, wherein the
protrusions are loose-fitted in either the through-holes or the
cavities of the sectorial color filter segments and are adhesively
fixed therein.
15. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a color wheel assembly as a
time-share light dispersing device, incorporating a color wheel
suitable for use as a filter element.
[0003] 2. Description of the Related Art
[0004] Color composition in a projection-type image display
apparatus has conventionally been accomplished commonly by a
method, such as: a single-panel method, in which one light valve
element adapted to control light amount per pixel thereby creating
an image is used to disperse each pixel into R (red), G (green),
and B (blue) lights; and a three-panel method, in which three light
valve elements dedicated to R, G and B lights, respectively, are
used to produce R, G and B images in parallel, and then the three
images thus produced are composed. Recently, as a light valve
element capable of fast switching, such as a ferroelectric liquid
crystal display element or a digital micro-mirror device, is
increasingly coming into practical use, a time-sharing single-panel
method is widely used. In the time-sharing single-panel method, R,
G and B lights are caused to sequentially impinge on one light
valve element, the light valve element is driven in synchronization
with switching-over of the R, G and B lights thereby producing R, G
and B images in a time-series manner, and the images thus produced
are projected onto a screen, or the like. Here, color composition
of the images is accomplished by a viewer due to an afterimage
effect occurring at a sense of vision. In the time-sharing
single-panel method, reduction in both dimension and weight of the
apparatus, which is a feature of a single-panel method, can be
achieved by employing a relatively simple optical system, and
therefore the time-sharing single-panel method is favorable for
realizing inexpensive fabrication of a projection-type image
display apparatus. In such an image display apparatus, a color
wheel is preferably used as a filter element of a time-share light
dispersing device to sequentially disperse light emitted from a
white light source into R, G and B lights having respective
wavelength bands in a time-sharing manner.
[0005] FIGS. 4A and 4B are respectively top plan and side views of
a conventional and typical color wheel assembly 200 as a time-share
light dispersing device including such a color wheel. Referring to
FIG. 4B, the color wheel assembly 200 comprises a color wheel 100,
and a driving motor 106 including a motor hub 105. The color wheel
150 is a tricolor color wheel composed of a disk-like substrate 101
which is made of a light-transmitting material, for example,
optical glass, and three pie-shaped (sectorial) filters 102, 103
and 104 which are formed on a surface of the substrate 101, and
which transmit exclusively, for example, R, G and B lights,
respectively. The color wheel 100 thus structured is fixedly
attached to the motor hub 105 coaxially therewith. The color wheel
assembly 200 operates such that the color wheel 100 is spun by the
driving motor 106 so that white light S impinges sequentially on
the filters (R, G and B) 102, 103 and 104 whereby the white light S
is sequentially dispersed into R, G and B lights.
[0006] FIGS. 5 and 6 show respectively top plan and exploded side
sectional view of a segment-type color wheel 160 comprising a
plurality (four in FIG. 5) of sectorial color filter segments
(hereinafter referred to as segments as appropriate) 112, 114, 116
and 118 which are separately prepared and are fixed in position by
means of a support member 120 and a clamp member 122 so as to form
a disk.
[0007] Specifically, as shown in FIG. 6, respective inner
circumferences 112a, 114a, 116a and 118a of the segments 112, 114,
116 and 118 are fitted to an outer circumference of a smaller
cylinder portion 120a of the support member 120 whereby the
segments 112, 114, 116 and 118 are duly set in position in the
radial direction of the color wheel 160, and respective surfaces of
the segments 112, 114, 116 and 118 toward the inner circumferences
112a, 114a, 116a and 118a are fitted to an annular seat portion
120b of the support member 120 whereby the segments 112, 114, 116
and 118 are duly set in position in the thickness direction of the
color wheel 160. Then, a smaller cylinder portion 122a of the clamp
member 122 is engagingly inserted into a hollow 120c of the support
member 120 so that an annular seat portion 122b of the clamp member
122 and the aforementioned annular seat portion 120b of the support
member 120 sandwich and clamp the inner circumferential portions of
the 112, 114, 116 and 118. And, when the support member 120 and the
clamp member 122 are bonded or screwed together, the segments 112,
114, 116 and 118 are fixed in position. The color wheel 160 thus
structured is fixedly attached to a hub (such as the hub 105 as
shown in FIGS. 4A and 4B) of a motor (such as the driving motor 106
as shown FIG. 4B) such that the hub is inserted in a hollow 122c of
the clamp member 122 (refer to, for example, Japanese Patent
Applications Laid-Open Nos. 2004-101827 ([0010], and FIG. 6
therein) and H10-48542 (claim 1, and FIG. 2 therein).
[0008] As described above, the color wheel 160 is attached to the
motor hub via the support member 120 and the clamp member 122 thus
resulting in increased numbers of components and manufacturing
processes, which inevitably involves increased production cost. The
clamp member 122 functions to join a color wheel and a motor hub,
and is a necessary component not only for a segment-type color
wheel but also for a monolithic-type color wheel in which color
filters are formed on a monolithic substrate therefore not
requiring the support member 120.
SUMMARY OF THE INVENTION
[0009] The present invention has been made in light of the
circumstances described above, and it is an object of the present
invention to inexpensively provide a high-precision color wheel
assembly as a time-share light dispersing device.
[0010] In order to achieve the object, according to one aspect of
the present invention, a color wheel assembly comprises: a driving
motor including a hub; and a color wheel which includes a plurality
of filters which either selectively transmit or selectively reflect
lights having respective wavelengths different from one another,
and which is attached directly to the hub of the driving motor.
With the construction described above, the structure and the
manufacturing processes for fixing the color wheel to the hub can
be simplified.
[0011] In the one aspect of the present invention, the color wheel
may comprise a plurality of sectorial color filter segments
arranged so as to form a disk. Consequently, in a color wheel
assembly incorporating a segment-type color wheel, the structure
and the manufacturing processes for fixing the color wheel to the
hub can be simplified.
[0012] In the one aspect of the present invention, the hub may have
protrusions, and the sectorial color filter segments may each have
at least one through-hole or cavity for receiving each of the
protrusions. Since the protrusions of the hub are engaged with the
through-holes or cavities of the sectorial color filter segment
thereby fixedly positioning the sectorial color filter segments
with respect to the hub in the radial direction of the color wheel,
the sectorial color filter segments can be surely prevented from
getting scattered off from the hub due to centrifugal force when
the color wheel spins at high speed. And no additional independent
components are used for fixing the sectorial color filter segments
to the hub.
[0013] In the one aspect of the present invention, the protrusions
may be each constituted by a pin or ball that is press-fitted into
each of through-holes or cavities formed at the hub, or that is
loose-fitted therein to be adhesively fixed. Since the pins or the
balls constituting the protrusions of the hub are engaged with the
through-holes or cavities of the sectorial color filter segment
thereby fixedly positioning the sectorial color filter segments
with respect to the hub in the radial direction of the color wheel,
the sectorial color filter segments can be surely prevented from
getting scattered off from the hub due to centrifugal force when
the color wheel spins at high speed.
[0014] In the one aspect of the present invention, the protrusions
may be engagingly inserted through the through-holes of the
sectorial color filter segments, and through the through-holes or
the cavities of the hub when the color wheel is placed on the hub
such that the through-holes of the sectorial color filter segments
coincide with the through-holes or the cavities of the hub.
Consequently, since the sectorial color filter segments are fixedly
positioned with respect to the hub in the radial direction of the
color wheel, the sectorial color filter segments can be surely
prevented from getting scattered off from the hub due to
centrifugal force when the color wheel spins at high speed.
[0015] In the one aspect of the present invention, the hub may be
formed by casting, molding or pressing so as to integrally include
the protrusions. Consequently, the number of components and the
number of manufacturing processes can be reduced.
[0016] In the one aspect of the present invention, the cavities
formed at the hub may be constituted by an annular groove or arc
grooves. Consequently, since the color wheel can turn with respect
to the hub after they are attached to each other, adhesive applied
therebetween can be preferably spread for enhanced bonding
strength.
[0017] In the one aspect of the present invention, the protrusions
may be press-fitted into the through-holes or the cavities of the
sectorial color filter segments, or loose-fitted therein to be
adhesively fixed.
[0018] And, in the one aspect of the present invention, the hub
constituting the driving motor may be assembled to the rest of
components of the motor after the color wheel is attached to the
hub. Consequently, since forces that are applied to the hub when
the color wheel is attached to the hub are not applied to bearings
which hold rotatably the hub with respect to the other portion of
the motor, problems related to defective bearings can be
suppressed.
[0019] Thus, a high-precision color wheel assembly as a time-share
light dispersing device can be inexpensively provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The above object and other advantages of the present
invention will become more apparent by describing in detail the
preferred embodiments of the present invention with reference to
the attached drawings in which:
[0021] FIGS. 1A and 1B are respectively exploded perspective and
assembled perspective views of a color wheel assembly according to
a first embodiment of the present invention;
[0022] FIG. 2 is an exploded perspective view (partly omitted) of a
color wheel assembly according to a second embodiment of the
present invention;
[0023] FIG. 3 is an exploded perspective view of a color wheel
assembly according to a third embodiment of the present
invention;
[0024] FIGS. 4A and 4B are respectively top plan and side views of
a conventional color wheel assembly;
[0025] FIG. 5 is a plan view of a conventional segment-type color
wheel; and
[0026] FIG. 6 is an exploded sectional view of the color wheel of
FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Preferred embodiments of the present invention will
hereinafter be described with reference to the accompanying
drawings.
[0028] Referring to FIGS. 1A and 1B, a color wheel assembly 10
according to a first embodiment of the present invention comprises
a motor hub 12 constituting a driving motor, and a monolithic-type
color wheel 14 attached directly to the motor hub 12 without using
any additional components as shown in FIG. 1B. In the present
embodiment, the color wheel 14 is adhesively fixed to the motor hub
12.
[0029] Referring now to FIG. 2, a color wheel assembly 10A
according to a second embodiment of the present invention comprises
a motor hub 12A constituting a driving motor, and a segment-type
color wheel 15 including a plurality of color filter segments (only
one color filter segment 18 is shown in the figure for the
convenience of explanation) and attached directly to the motor hub
12A. The motor hub 12A has a plurality of protrusions 16A (only two
are shown in the figure for the convenience of explanation), each
of the color filter segments (hereinafter referred to simply as
segments as appropriate) 18 et al. has through-holes or cavities
(through-holes in the figure) 26 for receiving the protrusions 16A,
and the segments 18 et al. constituting the color wheel 15 are
adhesively attached to the motor hub 12A such that the protrusions
16A are fitted into the through-holes 26, where the protrusions 16
may be press-fitted into the through-holes 26, or loose-fitted
therein to be adhesively fixed. In this connection, though not
shown, the motor hub 12A may be formed by casting, molding, or
pressing so as to integrally include the protrusions 16A.
[0030] Two through-holes 26 are formed at the segment in FIG. 2,
but alternately one through-hole 26 (as shown in FIG. 3), or three
or more through-holes 26 may be formed at each of the segments
including the segment 18, and the protrusions 16A are provided at
the motor hub 12A in a number corresponding to the total number of
the through-holes 26 formed on the segments 18 et al. Also, the
protrusion 16A, which is constituted by a simple cylinder in FIG.
2, may alternatively be constituted by, for example, a cylinder or
pin with a rounded top end, a semispherical object, or spherical
object such as a bearing ball. The protrusions 16A may be
press-fitted into holes formed at the motor hub 12A, or may be
loose-fitted therein to be adhesively fixed. The segments 18 et al.
are typically formed of glass, and the through-holes (or cavities)
26 may be formed by normal machining, ultrasonic machining,
blasting, laser machining, or the like.
[0031] The segments 18 et al. may alternatively be fixed to the
motor hub 12A in the following manner: the segments 18 et al. are
placed on the motor hub 12A with the holes but without the
protrusions 16A such that the through-holes (not cavities in this
case) 26 coincide with respective holes formed at the motor hub
12A; and then cylinders, pins, or cylindrical or spherical objects
constituting the protrusions 16A are press-fitted into both the
through-holes 26 of the segments 18 et al. and the holes of the
motor hub 12A, or loose-fitted therein to be adhesively fixed.
[0032] In any manner of fixing the segments 18 et al. to the motor
hub 12A, the protrusions 16A on the motor hub 12A are engaged with
the through-holes (or cavities) 26 of the segments 18 et al.,
whereby the segments 18 et al. are duly positioned with respect to
the motor hub 12A in the radial direction of the color wheel 15
when the color wheel assembly 10A is completed.
[0033] FIG. 3 shows a third embodiment of the present invention,
where the protrusions 16A of the second embodiment are constituted
by spherical objects, specifically balls 16B. In the third
embodiment, a color wheel assembly 10B comprises a motor hub 12B
constituting a motor, and a segment-type color wheel 15 including a
plurality (four in the figure) of color filter segments 18, 20, 22
and 24. Each of the segments 18, 20, 22 and 24 has at least one
(one in the figure) hole or cavity for accepting each of the balls
16B functioning as the protrusions 16A of the first embodiment, and
the motor hub 12B has an annular groove 30 formed on a surface
thereof facing the color wheel 15. The annular groove 30 is
positioned concentric with the rotation axis of the motor, and
adapted to freely receive the balls 16B. The annular groove 30 may
be interrupted at a regular interval into several arc grooves.
[0034] In the embodiments described above, the color wheel 14/15
may be attached to a motor such that the color wheel 14/15 is fixed
to the motor hub 12/12A/12B preassembled to the rest of the motor
components, or such that the color wheel 14/15 is fixed to the
motor hub 12/12A/12B yet to be assembled to the rest of the
components, and then the motor hub 12/12A/12B with the color wheel
14/15 fixed thereto is assembled to the rest of the motor
components.
[0035] According to the above-described embodiments of the present
invention, the following advantages are achieved.
[0036] Since the color wheel 14/15 is attached directly to the
motor hub 12/12A/12B of the motor without using any additional
components such as a support member or a clamp member, the
structure and the manufacturing process for fixing the color wheel
14/15 to the motor can be simplified. The resultant reduction in
the number of components lessens the number of factors to adversely
influence the rotational balance, whereby the balance adjusting
work can be eased and the balance-related problems can be reduced.
Thus, the color wheel assembly 10/10A/10B as a time-share light
dispersing device can be manufactured superiorly with a high degree
of precision and inexpensively with a reduced number of components
and a reduced number of assembling processes.
[0037] The present invention can be applied to a color wheel
assembly (such as the color wheel assembly 10A/10B) incorporating a
segment-type color wheel (such as the color wheel 15) as well as a
color wheel assembly incorporating a monolithic-type color wheel,
and achieves the same advantage described above.
[0038] In case of the color wheel assembly 10A according to the
second embodiment, the protrusions 16A constituted by pins or balls
press-fitted into the through-holes or cavities formed at the motor
hub 12A or loose-fitted therein to be adhesively fixed are engaged
with the through-holes or cavities 26 formed at the segments 18 et
al., whereby the segments 18 et al. can be duly and fixedly
positioned with respect to the motor hub 12A in the radial
direction of the color wheel 15. Consequently, the segments 18 et
al. can be surely prevented from getting scattered off from the
motor hub 12A due to centrifugal force when the color wheel 15
spins at high speed. The engagement may be implemented such that
the protrusions 16A are press-fitted through the through-holes 26
of the segments 18 et al. and the through-holes or cavities of the
motor hub 12A or loose-fitted therethrough to be adhesively fixed
after the color wheel 15 consisting of the segments 18 et al. is
placed on the motor hub 12A such that the through-holes 26 of the
segments 18 et al. coincide with the through-holes or cavities of
the motor hub 12A. In this connection, the motor hub 12A may be
formed by casting, molding, or pressing so as to integrally include
the protrusions 16A, in which case the numbers of components and
manufacturing processes can be further reduced.
[0039] Also, in case of the color wheel assembly 10B according to
the third embodiment, the balls 16B as an equivalent of the
protrusions 16A in the second embodiment are disposed so as to move
freely along the annular groove or arc grooves 30 of the motor hub
12B. Consequently, the color wheel 15 can turn with respect to the
motor hub 12B after they are attached to each other, so adhesive
applied therebetween can be preferably spread for enhanced bonding
strength.
[0040] Further, if the motor hub 12/12A/12B is assembled to the
rest of the motor components after the color wheel 14/15 is
attached to the motor hub 12/12A/12B, forces that are applied to
the motor hub 12/12A/12B when the color wheel 14/15 is attached to
the hub 12/12A/12B are not applied to bearings which hold rotatably
the hub 12/12A/12B with respect to the other portion of the motor,
whereby problems related to defective bearings can be
suppressed.
[0041] Obviously, many modifications and variations of the present
invention are possible in light of the above teachings. Thus, it is
to be understood that, within the scope of the appended claims, the
invention may be practiced otherwise than as specifically described
above.
* * * * *