U.S. patent application number 14/531239 was filed with the patent office on 2015-02-19 for optical scanning apparatus and image forming apparatus.
The applicant listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Takehiro Ishidate, Yasuaki Otoguro.
Application Number | 20150049373 14/531239 |
Document ID | / |
Family ID | 51525545 |
Filed Date | 2015-02-19 |
United States Patent
Application |
20150049373 |
Kind Code |
A1 |
Otoguro; Yasuaki ; et
al. |
February 19, 2015 |
OPTICAL SCANNING APPARATUS AND IMAGE FORMING APPARATUS
Abstract
An optical scanning apparatus capable of fixing an optical
member using a plate spring without forming a die cut hole and thus
having high dust-proof performance includes a mirror supporting
portion supporting a reflection mirror, and a projecting portion
configured to form a gap between the reflection mirror supported on
the mirror supporting portion and itself, and to deform the plate
spring with the reflection mirror, and the projecting portion is
provided with a cut hole for engaging the plate spring.
Inventors: |
Otoguro; Yasuaki;
(Abiko-shi, JP) ; Ishidate; Takehiro; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
|
JP |
|
|
Family ID: |
51525545 |
Appl. No.: |
14/531239 |
Filed: |
November 3, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14203199 |
Mar 10, 2014 |
8902268 |
|
|
14531239 |
|
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Current U.S.
Class: |
359/205.1 |
Current CPC
Class: |
G02B 26/125 20130101;
G03G 15/04045 20130101; G03G 2221/1654 20130101; G02B 27/0006
20130101; G03G 21/1666 20130101; G02B 7/00 20130101; G03G 13/04
20130101; G03G 2221/1678 20130101 |
Class at
Publication: |
359/205.1 |
International
Class: |
G02B 27/00 20060101
G02B027/00; G02B 7/00 20060101 G02B007/00; G02B 26/12 20060101
G02B026/12 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 12, 2013 |
JP |
2013-049101 |
Claims
1. An optical scanning apparatus including a light source
configured to emit a light beam, a rotating polygonal mirror
configured to deflect the light beam emitted from the light source
so that a photosensitive member is scanned with the light beam, an
optical member configured to guide the light beam deflected by the
rotating polygonal mirror to the photosensitive member, and a
casing accommodating the optical member therein, the optical
scanning apparatus comprising: a first supporting portion formed
integrally with the casing inside the casing and configured to
support one end of the optical member in a longitudinal direction
of the optical member; a second supporting portion formed
integrally with the casing inside the casing and configured to
support another end of the optical member in the longitudinal
direction of the optical member; a first projecting portion formed
integrally with the casing and projecting toward the inside of the
casing from the casing so that the first supporting portion and the
first projecting portion are formed in the casing to be adjacent
each other in a direction along a plane perpendicular to the
longitudinal direction of the optical member; a second projecting
portion formed integrally with the casing and projecting toward the
inside of the casing from the casing the second supporting portion
and the second projecting portion are formed in the casing to be
adjacent each other in the direction along the plane perpendicular
to the longitudinal direction of the optical member; a first plate
spring including a pressing portion configured to press the optical
member and a contact portion being in contact with the first
projecting portion, the first plate spring being configured to be
elastically deformed so that a relative position between the
pressing portion of the first plate spring and the contact portion
of the first plate spring changes, and to cause the pressing
portion of the first plate spring to press the optical member
toward the supporting portion by being fitted between the first
supporting potion and the first projecting portion to be
elastically deformed, a second plate spring including a pressing
portion configured to press the optical member and a contact
portion being in contact with the second projecting portion, the
second plate spring being configured to be elastically deformed so
that a relative position between the pressing portion of the second
plate spring and the contact portion of the second plate spring
changes, and to cause the pressing portion of the second plate
spring to press the optical member toward the supporting portion by
being fitted between the second supporting potion and the second
projecting portion to be elastically deformed, wherein the first
projecting portion is provided with a first through hole and the
first plate spring is provided with an engaging portion configured
to engage with an inner wall of the first through hole, and the
elastically deformed plate spring does not separate from between
the first supporting potion and the first projecting portion by the
engaging portion of the first plate spring and the inner wall of
the first through hole engaging; wherein the second projecting
portion is provided with a second through hole and the second plate
spring is provided with an engaging portion configured to engage
with an inner wall of the second through hole, and the elastically
deformed plate spring does not separate from between the second
supporting potion and the second projecting portion by the engaging
portion and the inner wall of the second through hole engaging.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 14/203,199, filed on Mar. 10, 2014, the
content of which is expressly incorporated by reference herein in
its entirety. This application also claims the benefit of Japanese
Patent Application No. 2013-049101 filed Mar. 12, 2013, which is
hereby incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a dust-proof measure for a
casing of an optical scanning apparatus used for an image forming
apparatus such as a copying machine, a printer, a facsimile, or
their multifunction peripheral.
[0004] 2. Description of the Related Art
[0005] As an optical scanning apparatus used for an
electrophotographic image forming apparatus, an optical scanning
apparatus having the following configuration has been well-known.
The optical scanning apparatus forms a latent image on a
photosensitive member by deflecting a light beam emitted from a
light source using a rotating polygonal mirror and guiding the
deflected light beam onto the photosensitive member using an
optical component including a lens or a mirror. FIG. 7 illustrates
an outline of components of a conventional optical scanning
apparatus that has generally been used. When dirt such as dust
adheres to an optical component installed in the optical scanning
apparatus, the dust adhering thereto blocks a light beam. Thus, an
amount of the light beam on a photosensitive member decreases. With
the decrease in the light amount of the light beam, an image is not
output at a desired density. In recent years, amounts of fine dust
and a chemical substance having a size of 1 .mu.m or less in the
air has increased. Deterioration in image quality due to dirt on
the optical component has been becoming an issue more than before.
Usually, the optical component serving as the component of the
optical scanning apparatus is accommodated in a casing illustrated
in FIGS. 8A, 8B, and 8C described below to protect the optical
component from a substance causing dirt.
[0006] FIGS. 8A, 8B, and 8C are schematic configuration diagrams
illustrating a retaining configuration of an optical component in a
casing 185 of a conventional optical scanning apparatus. As a
material for the casing 185, resin or a metal member is generally
used, and is formed by a die. On the outer wall of the casing 185,
a number of die cut holes H for forming an engaging portion 86b are
formed. A plate spring for fixing an optical member is attached to
the engaging portion 86b. FIGS. 9A and 9B illustrate how the die
cut hole H is formed during the formation of the casing 185. The
detailed description thereof will be given in an exemplary
embodiment described below. In a conventional product, the die cut
holes H are covered by affixing a number of sheet-type sealing
members to the outer wall of the casing 185 to prevent the optical
component from being soiled by dust, which has passed through the
die cut holes H, adhering thereto. However, the casing 185 may have
a number of ribs installed therein from the necessity of ensuring
rigidity and may have a complicated shape due to an arrangement
constraint of units around the image forming apparatus. If the ribs
are formed at positions where they prohibit the sealing members
from being affixed, the die cut holes H cannot be completely sealed
by the sealing members. There is no other choice but to affix the
sealing members by hands. Thus, a human error in the affixing may
occur.
[0007] Furthermore, with a recent increase in an image forming
speed, the rotating polygonal mirror needs to rotate at high speed.
When the rotating polygonal mirror rotates at high speed, air
current is generated in the optical scanning apparatus. The air
current causes a large pressure distribution difference in an inner
space of the optical scanning apparatus. Depending on areas, air
flows from inside to outside or from outside to inside. A force
caused by the air current is exerted on the optical scanning
apparatus more greatly than that in a conventional example. Air
flowing from outside to inside includes fine dust that soils the
optical component. Thus, as the apparatus operates, more fine dust
enters inward. The fine dust adheres to a surface of the optical
component and the inside of the casing 185. Particularly, dust
carried by surrounding air current and the rotating polygonal
mirror rotating at high speed collide with each other. Thus, the
dust is likely to adhere to a reflection surface of the rotating
polygonal mirror. More specifically, when the rotating polygonal
mirror rotates, a Karman vortex and turbulence are generated around
the reflection surface of the rotating polygonal mirror, and the
air current carrying the dust violently collides with the
reflection surface. As a result, the fine dust is accumulated on
the reflection surface of the rotating polygonal mirror. Thus, dirt
may increase from an area where an amount of collision of the air
current is large, so that the reflectance of the reflection surface
decreases. The amount of the light beam to be guided onto the
photosensitive member decreases, so that the image density
decreases.
[0008] To solve such an issue that the optical component is soiled,
a configuration in which the die cut holes H are covered using a
part of the plate spring installed inside the casing 185 has been
proposed. According to an optical scanning apparatus discussed in
Japanese Patent Application Laid-Open No. 2008-9319, for example,
an opening portion to be formed when a casing is formed is covered
by bending a tip end of a plate spring to ensure sealability of the
apparatus.
[0009] In a configuration discussed in Japanese Patent Application
Laid-Open No. 2008-9319, unlike a material such as a rubber
material or a sponge material, hard materials such as the plate
spring and the casing are fitted to each other. Thus, it is
difficult to completely cover the opening portion. If flatness and
straightness of a contact surface between the plate spring and the
casing 185 are distorted even by several micrometers, surface
contact or line contact cannot be made but partial point contact is
made between the plate spring and the casing. Thus, a gap is formed
between the plate spring and the casing. In other words, a gap
formed in a portion where the plate spring and the casing are in
point contact may be unsealable. Therefore, dust of several hundred
micrometers can be prevented from entering. However, fine particles
in the order of several micrometers as described above cannot be
prevented from entering.
SUMMARY OF THE INVENTION
[0010] The present disclosure is directed to an optical scanning
apparatus capable of fixing an optical member using a plate spring
without forming a die cut hole and thus having high dust-proof
performance.
[0011] According to an aspect of the present disclosure, an optical
scanning apparatus having a light source configured to emit a light
beam, a rotating polygonal mirror configured to deflect the light
beam emitted from the light source so that a photosensitive member
is scanned with the light beam, an optical member configured to
guide the light beam deflected by the rotating polygonal mirror to
the photosensitive member, and a casing housing the optical member
therein, the optical scanning apparatus includes a supporting
portion formed integrally with the casing inside the casing and
supporting the optical member, a gap forming portion formed
integrally with the casing inside the casing so a gap is formed
between the optical member supported by the supporting portion and
the gap forming portion, and a plate spring including a pressing
portion configured to press the optical member, and a contact
portion in contact with the gap forming portion, and configured to
be elastically deformed so that a relative position between the
pressing portion and the contact portion changes, and to cause the
pressing portion to press the optical member toward the supporting
portion by being fitted in the gap to be elastically deformed. The
gap forming portion is provided with a through hole and the plate
spring is provided with an engaging portion configured to engage
with an inner wall of the through hole, and the elastically
deformed plate spring does not separate from the gap due to the
engaging portion and the inner wall of the through hole engaging
each other.
[0012] According to another aspect of the present disclosure, an
optical scanning apparatus having a light source configured to emit
a light beam, a rotating polygonal mirror configured to deflect the
light beam emitted from the light source so a photosensitive member
is scanned with the light beam, an optical member configured to
guide the light beam deflected by the rotating polygonal mirror to
the photosensitive member, and a casing accommodating the optical
member therein, the optical scanning apparatus includes a
supporting portion formed integrally with the casing inside the
casing and supporting the optical member, a projecting portion
formed integrally with the casing and projecting toward the inside
of the casing from the casing so that a gap is formed between the
optical member supported on the supporting portion and the
projecting portion, and a plate spring including a pressing portion
configured to press the optical member and a contact portion in
contact with the projecting portion, the plate spring being
configured to be elastically deformed so that a relative position
between the pressing portion and the contact portion changes, and
to cause the pressing portion to press the optical member toward
the supporting portion by being fitted in the gap to be elastically
deformed. The projecting portion is provided with a through hole
and the plate spring is provided with an engaging portion
configured to engage with an inner wall of the through hole, and
the elastically deformed plate spring does not separate from the
gap due to the engaging portion and the inner wall of the through
hole engaging each other.
[0013] Further features of the present invention will become
apparent from the following description of exemplary embodiments
with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic configuration diagram illustrating an
outline of an image forming apparatus according to first and second
exemplary embodiments.
[0015] FIGS. 2A and 2B are schematic configuration diagrams
illustrating a configuration for improving dust-proof performance
according to the first exemplary embodiment.
[0016] FIGS. 3A, 3B, and 3C are a schematic diagram illustrating an
entire image of optical component attachment according to the first
exemplary embodiment, a schematic diagram illustrating installation
of a plate spring, and a diagram illustrating a configuration of
the plate spring, respectively.
[0017] FIGS. 4A, 4B, and 4C are schematic diagrams illustrating a
die structure when a casing according to the first exemplary
embodiment is formed.
[0018] FIG. 5 illustrates a rotation moment according to the first
exemplary embodiment.
[0019] FIGS. 6A and 6B are schematic configuration diagrams
illustrating a configuration for improving dust-proof performance
according to the second exemplary embodiment.
[0020] FIG. 7 is a schematic configuration diagram illustrating a
configuration of an optical scanning apparatus according to a
conventional example.
[0021] FIGS. 8A, 8B, and 8C are schematic diagrams illustrating a
retaining configuration of an optical component according to the
conventional example.
[0022] FIGS. 9A and 9B illustrate a die structure when a casing
according to the conventional example is formed.
DESCRIPTION OF THE EMBODIMENTS
[0023] Various exemplary embodiments, features, and aspects of the
invention will be described in detail below with reference to the
drawings. A configuration of a conventional optical scanning
apparatus will be described first, and then exemplary embodiments
will be described.
Configuration of Conventional Optical Scanning Apparatus
[0024] FIG. 7 illustrates an outline of components of an optical
scanning apparatus conventionally generally used. An optical
scanning apparatus, which irradiates a photosensitive member with a
light beam to form an electrostatic latent image, includes a
rotating polygonal mirror 42 serving as a deflector, a motor unit
41 for rotating the rotating polygonal mirror 42, and optical
members. The optical members include a collimator lens 43 and a
cylindrical lens 44 for shaping a light flux incident on the motor
unit 41. The optical members further include one or more f.theta.
lenses (hereinafter referred to as optical lenses) 60 for
equalizing a scanning speed of the light beam on the photosensitive
member and a reflection mirror 62 for guiding the light beam to the
photosensitive member. In the motor unit 41, the rotating polygonal
mirror 42 having a number of reflection mirror surfaces on its
outer periphery rotates at high speed, thereby deflecting the light
beam to be incident on the photosensitive member so that the
photosensitive member is scanned with the light beam.
[0025] A light amount of the light beam to be guided onto the
photosensitive member is deeply related to a density of an image
formed on a recording sheet (recording medium). Unintended
variation in the light amount causes a phenomenon that the image
density is low or high. Particularly if dirt such as dust adheres
to an optical component in the optical scanning apparatus, the dust
adhering thereto blocks the light beam. Thus, the light amount of
the light beam to be guided onto the photosensitive member
decreases, so that the image density decreases. As described above,
deterioration in image quality by fine dust having a size of 1
.mu.m or less soiling the optical component has been becoming an
issue. Usually, the optical component serving as the component of
the optical scanning apparatus is accommodated in a casing to be
protected from a substance causing dirt. In the following
description, a rotation axis direction of the rotating polygonal
mirror 42 in the motor unit 41 is a Z-axis direction, a main
scanning direction being a scanning direction of the light beam or
a longitudinal direction of the reflection mirror 62 is a Y-axis
direction, and a direction perpendicular to a Y-axis and a Z-axis
is an X-axis direction.
Casing of Optical Scanning Apparatus
[0026] For comparison with exemplary embodiments described below,
FIGS. 8A, 8B, and 8C illustrating the conventional example
described above will be described. FIGS. 8A, 8B, and 8C are
schematic configuration diagrams illustrating a retaining
configuration of an optical component in a casing 185 of a
conventional optical scanning apparatus. FIG. 8A is a perspective
view illustrating how a plate spring 195 fixes one end of a
reflection mirror 62, and is an enlarged view in the vicinity of
the end of the reflection mirror 62. FIG. 8B illustrates a position
where the reflection mirror 62 and the plate spring 195 are
installed in the casing 185. FIG. 8C is a cross-sectional view of a
portion where the plate spring 195 fixes the reflection mirror 62,
illustrating cut surfaces in a cross section (hatched portions) and
a structure of the inner side of the cross section. The other end
of the reflection mirror 62 has a similar supporting structure. The
reflection mirror 62 is indicated by a lattice portion. The
reflection mirror 62 is fixed on a supporting portion 87 in the
casing 185 by being pressed by the plate spring 195.
[0027] The casing 185 includes a projecting portion 86 projecting
from its bottom surface (inner wall surface) formed to attach the
plate spring 195 thereto. The projecting portion 86 is formed
integrally with the casing 185 to face the reflection mirror 62
supported on the supporting portion 87. An engaging portion 86b
serving as a protrusion with which the plate spring 195 engages is
provided on a facing surface 86a that faces the reflection mirror
62 in the projecting portion 86 projecting from the casing 185. The
engaging portion 86b projects toward the reflection mirror 62
supported on the supporting portion 87 from the facing surface
86a.
[0028] The plate spring 195 includes a pressing portion 195a for
pressing the reflection mirror 62 on the supporting portion 87
mainly in the X-axis direction, a pressing portion 195b for
pressing the reflection mirror 62 on the supporting portion 87
mainly in the -Z-axis direction, and an opening 195c into which the
engaging portion 86b is inserted. The plate spring 195 further
includes a plate portion 195d being in contact with the facing
surface 86a, a plate portion 195e on which the pressing portion
195a is formed, and a plate portion 195f on which the pressing
portion 195b is formed. A bending portion 195g connects the plate
portions 195d and 195e, and a bending portion 195h connects the
plate portions 195d and 195f. The plate portion 195d is provided
with the opening 195c having a larger projection area than that of
the engaging portion 86b and having an area enough for the engaging
portion 86b to enter.
[0029] From a viewpoint of space saving and workability of
installation, the plate spring 195 is not attached to the casing
185 with a screw but is fixed thereto by a reaction force received
by the pressing portion 195a from the reflection mirror 62
supported on the supporting portion 87 and engagement of the
engaging portion 86b and an inner wall surface of the opening 195c
in the plate spring 195. More specifically, when the optical
scanning apparatus is assembled, the plate spring 195 is inserted
into a gap between the projecting portion 86 and the reflection
mirror 62 on the supporting portion 87 by moving in the -Z-axis
direction. The bending portion 195g in the plate spring 195 is
elastically bent by being inserted into the gap between the
projecting portion 86 and the reflection mirror 62 on the
supporting portion 87. As illustrated in FIG. 8C, the engaging
portion 86b of the projecting portion 86 enters the inside of the
opening 195c provided on the plate portion 195d with the bending
portion 195g elastically bent. In this state, the bending portion
195g is elastically deformed, so that the pressing portion 195a
presses the reflection mirror 62. The reflection mirror 62 is fixed
on the supporting portion 87 by being pressed by the pressing
portion 195a.
[0030] The opening 195c and the engaging portion 86b constitute a
stopper mechanism provided to suppress separation of the plate
spring 195 sandwiched between the reflection mirror 62 and the
facing surface 86a from between the reflection mirror 62 and the
projecting portion 86. In a state illustrated in FIG. 8C, an upper
surface 86c of the engaging portion 86b and the opening 195c engage
with each other. Thus, the separation of the plate spring 195 from
between the reflection mirror 62 and the projecting portion 86 is
suppressed.
[0031] While the casing 185 is generally formed of resin or a metal
member molded by a die, an infinite number of die cut holes H
described above are formed on an outer wall of the casing 185, and
particularly on a bottom surface of the casing 185 in a formation
process described below.
Reason Why Die Cut Hole is Formed
[0032] For comparison with exemplary embodiments described below,
the reason why the die cut hole H is formed on the outer wall of
the casing 185 in a process for forming the engaging portion 86b in
the casing 185 illustrated in FIG. 8C will be described with
reference to FIGS. 9A and 9B. FIG. 9A is a cross-sectional view of
a portion where the engaging portion 86b is provided in the casing
185, illustrating cut surfaces of a cross section by hatching and
also illustrating a structure on the innermost side of the cross
section. FIG. 9B illustrates how two templates are attached
together. The casing 185 being a molded product is formed by being
sandwiched by a template A and a template B, respectively, from
above and from below, as illustrated in FIG. 9A. More specifically,
the casing 185 is formed by using roughly two types of templates,
i.e., the template A and the template B, and is formed by pouring
resin into a gap formed therebetween when the two templates are
attached together. The engaging portion 86b in the casing 185
cannot be formed by one template. The engaging portion 86b includes
an undercut portion 86d being a lower surface having a protrusion
shape. The undercut portion 86d can be formed only when two or more
templates are inserted thereinto from an outer shape of a product.
Thus, the casing 185 cannot be formed only by the template A. The
template B needs to be inserted into the casing 185 (toward the
template A), as illustrated in FIG. 9B. When the templates A and B
are detached from each other after resin is poured into the gap
between the templates A and B to form the casing 185, the template
B is drawn from the side of the bottom surface of the casing 185.
Therefore, the die cut hole H is formed by the template B on the
bottom surface of the casing 185.
Image Forming Apparatus
[0033] A configuration of an image forming apparatus according to a
first exemplary embodiment will be described. FIG. 1 is a schematic
configuration diagram illustrating an overall configuration of a
tandem type color laser beam printer according to the present
exemplary embodiment. The laser beam printer (hereinafter merely
referred to as a printer) includes four image forming engines 10Y,
10M, 10C, and 10Bk (indicated by a one-dot and dash line) for
forming toner images for colors, i.e., yellow (Y), magenta (M),
cyan (C), and black (Bk). The printer includes an intermediate
transfer belt 20 onto which the toner images are respectively
transferred from the image forming engines 10Y, 10M, 10C, and 10Bk.
The intermediate transfer belt 20 transfers a toner image
multiple-transferred on the intermediate transfer belt 20 onto a
recording sheet P serving as a recording medium to form a
full-color image. Signs Y, M, C, and Bk respectively representing
the colors will be omitted unless required.
[0034] The intermediate transfer belt 20 is endlessly formed, and
is wound around a pair of belt conveyance rollers 21 and 22, and is
configured so that the toner images formed by the image forming
engines 10 are transferred thereonto while rotating in a direction
indicated by an arrow B. A secondary transfer roller 65 disposed at
a position opposing the belt conveyance roller 21 nips the
intermediate transfer belt 20 therebetween. The recording sheet P
is inserted between the secondary transfer roller 65 and the
intermediate transfer belt 20, which pressure-contact each other,
so that the toner image is transferred thereonto from the
intermediate transfer belt 20. The four image forming engines 10Y,
10M, 10C, and 10Bk described above are disposed in parallel below
the intermediate transfer belt 20. The toner images formed
according to image information about each color are respectively
transferred onto the intermediate transfer belt 20 (hereinafter
referred to as "primary transfer"). The four image forming engines
10, i.e., the image forming engine 10Y for yellow, the image
forming engine 10M for magenta, the image forming engine 10C for
cyan, and the image forming engine 10Bk for black are disposed in
this order along a rotation direction (a direction indicated by the
arrow B) of the intermediate transfer belt 20.
[0035] Below the image forming engines 10, an optical scanning
apparatus 40 is disposed. The optical scanning apparatus 40 exposes
photosensitive drums 50 serving as photosensitive members being
respectively provided in the image forming engines 10, according to
the image information. The optical scanning apparatus 40 will be
described below with reference to FIGS. 2A, 2B, 3A, 3B, and 3C
although detailed illustration and description thereof are omitted
in FIG. 1. The optical scanning apparatus 40 is shared among the
image forming engines 10Y, 10M, 10C, and 10Bk, and includes four
semiconductor lasers (not illustrated) for respectively emitting
laser beams modulated according to the image information about each
color. The optical scanning apparatus 40 includes a rotating
polygonal mirror 42 and a motor unit 41. The rotating polygonal
mirror 42 deflects the light beams corresponding to the respective
photosensitive drums 50 so that the photosensitive drums 50 is
scanned with the light beams along an axial direction (the Y-axis
direction) of the photosensitive drums 50. The motor unit 41
rotates the rotating polygonal mirror 42. The light beams deflected
by the rotating polygonal mirror 42 are guided to an optical member
installed in the optical scanning apparatus 40 and respectively
guided onto the photosensitive drums 50 to expose the
photosensitive drums 50.
[0036] Each of the image forming engines 10 includes the
photosensitive drum 50 and a charging roller 12. The charging
roller 12 charges the photosensitive drum 50 to a uniform
background potential. Each of the image forming engines 10 further
includes a development unit 13, which develops an electrostatic
latent image formed on the photosensitive drum 50 by being exposed
with the light beam to form the toner image. The development unit
13 forms the toner image corresponding to the image information
about each color on the photosensitive drum 50.
[0037] A primary transfer roller 15 is disposed at a position
opposite the photosensitive drum 50 in each of the image forming
engines 10 so that the intermediate transfer belt 20 is nipped
therebetween. A predetermined transfer voltage is applied to the
primary transfer roller 15, so that the toner image on the
photosensitive drum 50 is transferred onto the intermediate
transfer belt 20.
[0038] Meanwhile, the recording sheet P is fed from a sheet feeding
cassette 2 accommodated in a lower part of a printer casing 1 to
the inside of the printer, specifically a secondary transfer
position where the intermediate transfer belt 20 and the secondary
transfer roller 65 abut on each other. A pickup roller 24 for
pulling out the recording sheet P stored in the sheet feeding
cassette 2 and a sheet feeding roller 25 are provided in parallel
in an upper part of the sheet feeding cassette 2. A retard roller
26 for preventing double feeding of the recording sheet P is
disposed at a position opposite the sheet feeding roller 25. A
conveyance path 27 of the recording sheet P inside the printer is
provided in a substantially vertical direction along a right side
surface of the printer casing 1. The recording sheet P, which has
been pulled out of the sheet feeding cassette 2 positioned at the
bottom of the printer casing 1, is conveyed upward in the
conveyance path 27, and fed to a registration roller 29. The
registration roller 29 controls timing when the recording sheet P
reaches the secondary transfer position. Then, the recording sheet
P is fed to a fixing device 3 (indicated by a broken line) provided
on the downstream side in a conveyance direction after the toner
image has been transferred thereonto at the secondary transfer
position. The recording sheet P on which the toner image has been
fixed by the fixing device 3 is discharged into a sheet discharge
tray la provided in an upper part of the printer casing 1 via a
discharge roller 28.
[0039] In forming the full-color image by the color laser beam
printer thus configured, the optical scanning apparatus 40 exposes
the photosensitive drums 50 in the image forming engines 10 at
predetermined timing, according to the image information about each
color. Thus, the latent image corresponding to the image
information is formed on the photosensitive drum 50 in each of the
image forming engines 10. To obtain a high quality image, the
latent image formed by the optical scanning apparatus 40 needs to
be reproduced accurately at a predetermined position on the
photosensitive drum 50, and an amount of the light beam for forming
the latent image needs to be always stable at a desired value.
Supporting Configuration of Optical Component In Casing
[0040] FIGS. 2A and 2B are schematic configuration diagrams
illustrating an optical component supporting configuration for
improving dust-proof performance according to the present exemplary
embodiment. FIG. 3A is a schematic diagram illustrating an entire
image of optical component attachment, and FIG. 3B is a schematic
diagram illustrating installation of a reflection mirror 62 serving
as an optical member and a plate spring 95 serving as its fixing
member in the casing 85. The optical scanning apparatus 40 is
illustrated in FIG. 3B with an upper cover 70 removed from the
casing 85. FIG. 3C illustrates a configuration of the plate spring
95. A light source unit 55 loaded with a light source for emitting
light beams (laser light), the rotating polygonal mirror 42 for
deflecting the light beams, and the motor unit 41 are installed
inside and in the outer periphery of the optical scanning apparatus
40. Furthermore, optical lenses 60a to 60d and reflection mirrors
62a to 62h for guiding each of the light beams onto the
photosensitive drum 50 and forming images are installed in the
optical scanning apparatus 40.
[0041] A light beam LY, corresponding to a photosensitive drum 50Y,
emitted from the light source unit 55 is deflected by the rotating
polygonal mirror 42, and is incident on the lens 60a. The light
beam LY, which has passed through the lens 60a, is incident on the
lens 60b, and is reflected by the reflection mirror 62a after
passing through the lens 60b. The light beam LY, which has been
reflected by the reflection mirror 62a, passes through a
transparent window (not illustrated), so that the photosensitive
drum 50Y is scanned with the light beam LY.
[0042] A light beam LM, corresponding to a photosensitive drum 50M,
emitted from the light source unit 55 is deflected by the rotating
polygonal mirror 42, and is incident on the lens 60a. The light
beam LM, which has passed through the lens 60a, is incident on the
lens 60b, and is reflected by the reflection mirrors 62b, 62c, and
62d after passing through the lens 60b. The light beam LM, which
has been reflected by the reflection mirror 62d, passes through a
transparent window (not illustrated), so that the photosensitive
drum 50M is scanned with the light beam LM.
[0043] A light beam LC, corresponding to a photosensitive drum 50C,
emitted from the light source unit 55 is deflected by the rotating
polygonal mirror 42, and is incident on the lens 60c. The light
beam LC, which has passed through the lens 60c, is incident on the
lens 60d, and is reflected by the reflection mirrors 62e, 62f, and
62g after passing through the lens 60d. The light beam LC, which
has been reflected by the reflection mirror 62g, passes through a
transparent window (not illustrated), so that the photosensitive
drum 50C is scanned with the light beam LC.
[0044] A light beam LBk, corresponding to a photosensitive drum
50Bk, emitted from the light source unit 55 is deflected by the
rotating polygonal mirror 42, and is incident on the lens 60c. The
light beam LBk, which has passed through the lens 60c, is incident
on the lens 60d, and is reflected by the reflection mirror 62h
after passing through the lens 60d. The light beam LBk, which has
been reflected by the reflection mirror 62h, passes through a
transparent window (not illustrated), so that the photosensitive
drum 50Bk is scanned with the light beam LBk.
[0045] The reflection mirrors 62a to 62h illustrated in FIG. 3A
correspond to the reflection mirror 62 illustrated in FIG. 7. The
lenses 60a to 60d illustrated in FIG. 3A correspond to the optical
lens 60 illustrated in FIG. 7. The reflection mirrors 62a to 60h
will be described below as the reflection mirror 62.
[0046] As illustrated in FIG. 3B, the reflection mirror 62 is fixed
to the casing 85 by being pressed toward a mirror supporting
portion 31 described below by the plate spring 95 inside the casing
85. A configuration of the plate spring 95 and the casing 85 will
be described below with reference to FIGS. 2A, 2B, 3A, 3B, and 3C.
The plate spring 95, and the mirror supporting portion 31 and a
projecting portion 33 described below constitute a mirror fixing
mechanism. The mirror fixing mechanism may be used to fix all the
plurality of reflection mirrors 62a to 62h, or may be used to fix
some of the reflection mirrors 62a to 62h.
Configuration of Plate Spring
[0047] The plate spring 95 serving as an elastic member illustrated
in FIG. 3C is formed by folding one thin plate. The plate spring 95
includes a first plate portion 95h including a reference surface
95a, and a second plate portion 95i, a third plate portion 95j, and
a pair of fourth plate portions 95k that are respectively folded
with respect to the first plate portion 95h.
[0048] The first plate portion 95h is a contact portion being in
contact with the projecting portion 33 described below and receives
a repulsive force from the projecting portion 33. A bending portion
95p connects the first plate portion 95h and the second plate
portion 95i. The bending portion 95p is formed by folding back the
second plate portion 95i in a substantially V shape with respect to
the first plate portion 95h. Relative position (a relative angle)
between the first plate portion 95h and the second plate portion
95i changes when the bending portion 95p is elastically deformed. A
bending portion 95o connects the first plate portion 95h and the
third plate portion 95j. The bending portion 95o is formed by
folding the third plate portion 95j at a substantially right angle
to the first plate portion 95h. Relative position (a relative
angle) between the first plate portion 95h and the third plate
portion 95j changes when the bending portion 95o is elastically
deformed. The pair of fourth plate portions 95k is folded at a
substantially right angle to the opposite side of the second plate
portion 95i and the third plate portion 95j from both ends of the
first plate portion 95h.
[0049] The reference surface 95a is one surface of the first plate
portion 95h having a thin plate shape, and abuts on a rectangular
column portion 33a in the projecting portion 33 provided in the
casing 85, and serves as a reference of a position of the plate
spring 95 (see FIGS. 2A and 2B). A first pressing portion 95b for
pressing the reflection mirror 62 is formed in the second plate
portion 95i. The first pressing portion 95b is a portion at a tip
end of the second plate portion 95i and bent in a convex shape to
project to the opposite side of the first plate portion 95h. When
the second plate portion 95i and the first plate portion 95h in the
plate spring 95 are inserted between the reflection mirror 62 and
the projecting portion 33 in a deflected (compressed) state against
an elastic force, the first pressing portion 95b abuts on a mirror
reflection surface 623 of the reflection mirror 62. Thus, the first
pressing portion 95b presses the reflection mirror 62 toward a
first mirror seat surface 31a, described below, serving as a
supporting portion for supporting a mirror.
[0050] A second pressing portion 95c for pressing the reflection
mirror 62 is formed on the third plate portion 95j. The second
pressing portion 95c is a portion for pressing the reflection
mirror 62 between a tip end 95d of the third plate portion 95j and
a folded part obtained by folding the third plate portion 95j at an
obtuse angle. The second pressing portion 95c abuts on a ridge
portion 622 in the reflection mirror 62. When the plate spring 95
is locked to the projecting portion 33 with the third projecting
portion 95j in the plate spring 95 deflected against an elastic
force with respect to the first plate portion 95h, the second
pressing portion 95c presses the reflection mirror 62 toward the
first mirror seat surface 31a and a second mirror seat surface 31b
of the mirror supporting portion 31.
[0051] A hole portion 95e is an opening provided on the reference
surface 95a and penetrating both surfaces of the first plate
portion 95h. An engaging portion 96 is an engaging claw projecting
from the reference surface 95a by folding a part of the plate
spring 95 covering a part of the hole portion 95e to the opposite
side of the second plate portion 95i and the third plate portion
95j.
[0052] Stoppers 95n are formed in a lower part of the first plate
portion 95h and at both ends of the bending portion 95p. The
stopper 95n abuts on a surface 33b of the projecting portion 33 to
receive a normal force in the -X-axis direction from the surface
33b.
[0053] Thus, the plate spring 95 causes the engaging portion 96
formed in the plate spring 95 itself to engage with an engaging
portion K provided in the casing 85. Thus, a posture of the plate
spring 95 can be kept without the plate spring 95 coming off the
casing 85 by a repulsive force from the reflection mirror 62. While
the portions of the plate spring 95 are illustrated with detailed
signs in FIG. 3C, the signs are omitted in the other figures for
the sake of simplification.
Configuration of Projecting Portion and Mirror Supporting
Portion
[0054] As illustrated in FIGS. 2A and 2B, the projecting portion 33
for retaining the plate spring 95 and the mirror supporting portion
31 for supporting the reflection mirror 62 to accurately attach the
reflection mirror 62 to the casing 85 are integrally formed in the
casing 85. The projecting portion 33 includes the rectangular
column portion 33a. The projecting portion 33 including the
rectangular column portion 33a is a gap forming portion for forming
a gap between the reflection mirror 62 supported on the mirror
supporting portion 31 (on the supporting portion 87) described
below and itself. The rectangular column portion 33a in the Y-axis
direction is formed in the casing 85 so that the width of the
rectangular column portion 33a is slightly narrower than the width
of the pair of fourth plate portions 95k. The rectangular column
portion 33a has a function of guiding the plate spring 95 by being
inserted between the fourth plate portions 95k when the plate
spring 95 is inserted between the reflection mirror 62 and the
projecting portion 33 from the +Z-axis direction.
[0055] The mirror supporting portion 31 includes the first mirror
seat surface 31a and the second mirror seat surface 31b on which
the reflection mirror 62 being pressed by the first pressing
portion 95b and the second pressing portion 95c in the plate spring
95 abuts. The first mirror seat surface 31a supports a reverse
surface of the mirror reflecting surface 623 of the reflection
mirror 62 with respect to a pressed point of the reflection mirror
62 to be pressed by the first pressing portion 95b in the plate
spring 95.
[0056] The rectangular column portion 33a in the projecting portion
33 is provided with a cut hole J. The cut hole J is a through hole
penetrating a surface on the opposite side of the mirror supporting
portion 31 from a surface, on the side on which the mirror
supporting portion 31 is arranged, of the rectangular column
portion 33a to separate from the reflection mirror 62 on the mirror
supporting portion 31. More specifically, the cut hole J is formed
in the projecting portion 33 of the casing 85 so that a direction
to which the cut hole J opens is a direction different from a
direction (the Z-axis direction) perpendicular to a bottom surface
(a plane parallel to an XY plane) of the casing 85. In the present
exemplary embodiment, the cut hole J is formed so that the
direction in which the cut hole J opens is within a plane parallel
to an XZ plane and is a direction (i.e., the X-axis direction)
parallel to the bottom surface of the casing 85 as an example.
[0057] As illustrated in FIG. 2B, the plate spring 95 is fitted in
an elastically deformed state in a gap formed by the projecting
portion 33 and the reflection mirror 62 laid on the mirror
supporting portion 31. As illustrated in FIG. 2B, the first
pressing portion 95b receives a normal force N from the reflection
mirror 62. The normal force N is decomposed into a force Z.sub.1
exerted in the -Z-axis direction on the plate spring 95 and a force
X.sub.1 exerted thereon in the -X-axis direction. The force X.sub.1
is a force for urging the plate spring 95 toward the rectangular
column portion 33a in the projecting portion 33.
[0058] On the other hand, in the first pressing portion 95b, the
force Z.sub.1 is exerted in the +Z-axis direction on the plate
spring 95. A force Z.sub.2 is exerted in the +Z-axis direction from
the reflection mirror 62 on the second pressing portion 95c. The
optical scanning apparatus according to the present exemplary
embodiment has a configuration in which the engaging portion 96 in
the plate spring 95 is caught by an inner wall (the engaging
portion K) on the upper side of the cut hole J so that the plate
spring 95 does not separate from between the projecting portion 33
and the reflection mirror 62 by the forces Z.sub.1 and Z.sub.2
being exerted on the plate spring 95. When the engaging portion 96
in the plate spring 95 abuts on the inner wall of the cut hole J, a
force Z.sub.3 in the -Z-axis direction is exerted on the plate
spring 95 at an abutment portion. The force Z.sub.3 is balanced
with the forces Z.sub.1 and Z.sub.2. Furthermore, a force X.sub.2
in the +X-axis direction is exerted on the plate spring 95 by the
reference surface 95a of the plate spring 95 abutting on the
rectangular column portion 33a in the projecting portion 33. The
force X.sub.2 is balanced with the force X.sub.1. The stopper 95n
abuts on the surface 33b of the projecting portion 33 and receives
a normal force N in the -X-axis direction from the surface 33b so
that the plate spring 95 does not rotate by a rotation moment in a
counterclockwise direction in FIG. 2B to be exerted on the plate
spring 95 by the forces Z.sub.1, Z.sub.2, and Z.sub.3. Similar to
the forces X.sub.1 and X.sub.2, respective points of action of the
forces X.sub.1 and X.sub.2 are shifted in the Z-axis direction.
Thus, the rotation moment is generated in the counterclockwise
direction in FIG. 2B. However, the stopper 95n prevents the plate
spring 95 from rotating, as described above.
[0059] As described above, the plate spring 95 does not separate
from (come off) between the projecting portion 33 and the
reflection mirror 62. The plate spring 95 is elastically deformed
by being fitted between the projecting portion 33 and the
reflection mirror 62. Thus, the reflection mirror 62 is pressed
toward the mirror supporting portion 31 upon receipt of a force (a
reaction force of the normal force N) from the plate spring 95.
[0060] As the above-described cut hole J is provided, a shape of
the engaging portion K can be formed without providing the cut hole
H described in FIGS. 9A and 9B. The reason for this will be
described below.
Process for Forming Casing
[0061] FIGS. 4A, 4B, and 4C are schematic diagrams illustrating a
die structure when the casing 85 according to the present exemplary
embodiment is formed. A forming die of the casing 85 has respective
die structures of forming dies A and B configured to be movable in
a vertical direction in FIGS. 4A, 4B, and 4C and forming most of
the casing 85, and a forming die C configured to be movable in a
direction different from the vertical direction. The forming die C
is a forming die for forming the cut hole J including the engaging
portion K in the projecting portion 33. The forming die C has a
protrusion Ca for forming the cut hole J. The forming die C has a
surface, on the opposite side on which the protrusion Ca projects
from its main body Cb, inclined in the vertical direction, as
illustrated in FIGS. 4A, 4B, and 4C, and has a trapezoidal shape as
viewed from a main scanning direction (the Y-axis direction). As
illustrated in FIG. 4A, a surface, which abuts on the forming die
C, of the forming die A is inclined to be in touch with the
inclined surface of the forming die C. The length in the main
scanning direction (the Y-axis direction) of the cut hole J is
determined depending on the length in the main scanning direction
of the protrusion Ca of the forming die C, i.e., the depth of the
protrusion Ca (i.e., the thickness of a part of the protrusion Ca)
in FIGS. 4A, 4B, and 4C. The width in the Z-axis direction of the
cut hole J is determined depending on the length in the Z-axis
direction of the protrusion Ca of the forming die C. The length in
the Y-axis direction of the protrusion Ca may be at least the
length in the Y-axis direction of the engaging portion 96 in the
plate spring 95 that has been projected on a YZ plane from the
X-axis direction. The length in the Z-axis direction of the
protrusion Ca may be at least the length in the Z-axis direction of
the engaging portion 96 in the plate spring 95 that has been
projected on the YZ plane from the X-axis direction.
[0062] As illustrated in FIG. 4A, to form the casing 85, the
forming dies A, B, and C are combined, and melted resin to become
the casing 85 is injected and filled into a gap between the
combined forming dies, followed by cooling. Then, as illustrated in
FIG. 4B, the forming die A moves in a direction indicated by an
arrow Y1, and the forming die B moves in a direction indicated by
an arrow Y2. Thus, a space enough for the forming die C to move is
formed on the opposite side (the left side) of the side on which
the forming die C has the protrusion Ca. As illustrated in FIG. 4C,
the forming die C moves in a direction indicated by an arrow Y3
toward a space on the left side of the forming die C. When the
forming die C moves in the direction indicated by the arrow Y3, the
protrusion Ca of the forming die C comes off the projecting portion
33 in the formed casing 85. As a result, the cut hole J is formed.
The forming die C moves in a direction indicated by an arrow Y4
that is the same direction as the direction indicated by the arrow
Y1 in which the forming die A has moved. A space on the left side
of the forming die C illustrated in FIG. 4C is formed by moving the
forming die A in the direction indicated by the arrow Y1. Thus,
only the forming die A may move in the direction indicated by the
arrow Y1 before the forming die C moves, and the forming die B may
move after the forming die C moves.
[0063] In the present exemplary embodiment, the projecting portion
33 is provided in proximity to the mirror supporting portion 31.
Thus, the forming die C is moved in a direction away from the
mirror supporting portion 31 illustrated in FIGS. 2A and 2B when
being drawn from the projecting portion 33. The reason for this
will be described. When a distance between the projecting portion
33 and the mirror supporting portion 31 is lengthened, the plate
spring 95 needs to be larger. In such a configuration, when a plate
spring having low rigidity is used to fix the reflection mirror 62,
a position of the reflection mirror 62 varies due to vibration
caused by rotation of the rotating polygonal mirror 42. On the
other hand, a plate spring having high rigidity is high in cost, so
that its use affects the manufacturing cost of the image forming
apparatus. Therefore, the projecting portion 33 is provided in
proximity to (adjacent to) the mirror supporting portion 31 in a
direction of an axis of the lens 60a and/or 60c (X-axis direction).
More specifically, the projecting portion 33 faces the mirror
supporting portion 31 in the direction of an axis of the lens 60a
and/or 60c(X-axis direction).
[0064] Thus, the projecting portion 33 and the mirror supporting
portion 31 are arranged in proximity to each other. When the
forming die C is slid toward the mirror supporting portion 31,
therefore, the mirror supporting portion 31 and the forming die C
interfere with each other. Accordingly, the protrusion Ca cannot be
drawn from the cut hole J. Therefore, a method for forming the
casing 85 by sliding the forming die C in a direction away from the
mirror supporting portion 31 to draw the protrusion Ca from the cut
hole J is used as a method for forming the casing 85 in the present
exemplary embodiment.
[0065] The following configuration can be used to provide a
movement space of the forming die C on the side on which the mirror
supporting portion 31 is arranged with respect to the projecting
portion 33. The mirror supporting portion 31 can be formed at a
position shifted in the main scanning direction (the Y-axis
direction), i.e., the longitudinal direction of the reflection
mirror 62 from a position of the projecting portion 33. FIG. 5 is a
schematic diagram of one of both ends, at which the reflection
mirror 62 (indicated by a two-dot and dash line) is supported and
fixed, of the reflection mirror 62 as viewed from above (the Z-axis
direction). To make illustration easy to understand, the engaging
portion K in the projecting portion 33, the plate spring 95, the
reflection mirror 62, and a mirror supporting seat surface 98
(corresponding to the first mirror seat surface 31a) of the mirror
supporting portion 31 are shifted in a horizontal direction (the
X-axis direction). As illustrated in FIG. 5, a space to which the
forming die C is to move, as indicated by a broken line, can be
provided by shifting the cut hole J serving as the engaging portion
K and the mirror supporting seat surface 98 in the longitudinal
direction (indicated by an unfilled arrow) of the reflection mirror
62. Thus, the engaging portion K can be formed using a forming die
that moves in a direction closer to the mirror supporting portion
31 (a direction indicated by an arrow X1). The cut hole J serves as
the engaging portion K because the cut hole J is always formed by
the forming die to form the engaging portion K, and the engaging
portion K and the cut hole J always constitute a set.
[0066] However, the engaging portion K for supporting the plate
spring 95 against a repulsive force from the reflection mirror 62
is shifted in the longitudinal direction of the reflection mirror
62. Thus, a rotation moment M is generated in the plate spring 95.
Therefore, in a configuration in which the forming die C is moved
in a direction closer to the mirror supporting portion 31, the
plate spring 95 is not stably retained in the projecting portion
33, so that the reflection mirror 62 cannot be sufficiently
pressed. Furthermore, the plate spring 95 needs to be shaped such
that the first plate portion 95h including the engaging portion 96,
the second plate portion 95i including the first pressing portion
95b, and the third plate portion 95j including the second pressing
portion 95c are shifted in the longitudinal direction of the
reflection mirror 62. Therefore, the configuration of the plate
spring 95 becomes complicated.
[0067] On the other hand, in the present exemplary embodiment, the
engaging portion K for supporting the plate spring 95 against a
repulsive force from the reflection mirror 62 matches (is not
shifted from) the plate spring 95 in the longitudinal direction of
the reflection mirror 62. Therefore, in the configuration of the
present exemplary embodiment, the plate spring 95 is fitted between
the projecting portion 33 and the reflection mirror 62 without the
rotation moment M being applied thereto. The number of die cut
holes (the die cut holes H illustrated in FIG. 9A in the
conventional example), which have been dotted on the outer wall of
the casing 85 to form an undercut portion (the undercut portion 86d
illustrated in FIG. 9B in the conventional example) of the engaging
portion K, can be significantly reduced. Thus, the issue that fine
dust enters the optical scanning apparatus from outside to soil the
optical component, the issue that the cost of the sealing member
for closing the die cut hole H is increased, the issue that the
number of manufacturing processes for attaching the sealing member
to the casing 85 is increased can be improved. The number of die
cut holes H to be formed on the outer wall of the casing 85 can be
reduced. Thus, a decrease in rigidity of the casing 85 can be
suppressed.
[0068] As described above, according to the present exemplary
embodiment, there can be provided an optical scanning apparatus
capable of fixing an optical member using a plate spring without
forming a die cut hole and thus having high dust-proof performance.
The number of die cut holes H formed in the casing 85 can be
reduced. Thus, the rigidity of the casing 85 can be prevented from
decreasing.
[0069] FIGS. 6A and 6B are schematic configuration diagrams
illustrating a second exemplary embodiment. In the present
exemplary embodiment, a cut hole J2 provided in the vicinity of an
engaging portion K forms an opening portion outspreading under a
lowermost point S of a plate spring 95-2 that engages with the
engaging portion K. The lowermost point S of the plate spring 95-2
corresponds to the bending portion 95p formed by folding the second
plate portion 95i in a substantially V shape with respect to the
first plate portion 95h in the plate spring 95, described in the
first exemplary embodiment.
[0070] As the plate spring 95-2 is thus configured, the engaging
portion K can be formed as a casing protrusion configured to enter
in a hole portion 95e provided in the plate spring 95-2. More
specifically, the plate spring 95-2 can be provided with only the
hole portion 95e having a simple hole shape without being provided
with the engaging portion 96 provided in the plate spring 95 in the
first exemplary embodiment. Therefore, the configuration of the
plate spring 95-2 can be made simpler. The other configuration of
the plate spring 95-2 is similar to that of the plate spring 95 in
the first exemplary embodiment, and hence description thereof is
not repeated. In this case, the engaging portion K in a casing 85
engages with the hole portion 95e in the plate spring 95-2.
[0071] The length in a Z-axis direction of the cut hole J2 may be
at least the length in the Z-axis direction of a portion from a
portion where the engaging portion K engages with the hole portion
95e in the plate spring 95-2 to the lowermost point S that has been
projected onto a YZ plane from an X-axis direction, i.e., may be a
length enough for the lowermost point S of the plate spring 95-2 to
enter the cut hole J2. The length in a Y-axis direction of the cut
hole J2 may be at least the width (the length in the Y-axis
direction) of a first plate portion 95h in the plate spring 95-2.
In this case, a fourth plate portion 95k in the plate spring 95-2,
for example, may sandwich a rectangular column portion 33a in a
projecting portion 33 from both the sides in the Y-axis direction,
as illustrated in FIG. 2A in the first exemplary embodiment. The
fourth plate portion 95k in the plate spring 95-2, for example, may
enter the cut hole J2 to press the projecting portion 33 outward
from inside the cut hole J2. Furthermore, in the first plate
portion 95h in the plate spring 95-2, only a portion having the
same length as that in the Y-axis direction of the hole portion 95e
may have a shape to cut into the cut hole J2, and the length in the
Y-axis direction of the cut hole J2 may be not less than the length
in the Y-axis direction of the hole portion 95e. The shape of the
plate spring 95-2 can be formed by changing a configuration of each
of the portions in the plate spring 95-2 in various forms so that
the engaging portion K engages with the hole portion 95e and the
lowermost point S of the plate spring 95-2 enters the cut hole J2.
To support the plate spring 95-2 that has been changed in various
forms, a configuration of the projecting portion 33 can also be
changed depending on the configuration of the plate spring
95-2.
[0072] As described above, according to the present exemplary
embodiment, there can be provided an optical scanning apparatus
capable of fixing an optical member using a plate spring without
forming a die cut hole and thus having high dust-proof
performance.
[0073] The casing 85 including the cut hole J described in the
first and second exemplary embodiments is applicable to a casing in
which an engaging portion for engaging a plate spring for pressing
an optical component is to be formed. The present invention is not
limited to the above-described optical scanning apparatus but
applicable to an optical scanning apparatus in which a plate spring
engages with a casing to press an optical component toward the
casing. Furthermore, the present invention is not limited to the
image forming apparatus described in FIG. 1 but applicable to an
image forming apparatus including an optical scanning apparatus in
which a plate spring engages with a casing to press an optical
component toward the casing.
[0074] According to the exemplary embodiments of the present
invention, there can be provided an optical scanning apparatus
capable of fixing an optical member using a plate spring without
forming a die cut hole and thus having high dust-proof
performance.
[0075] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0076] This application claims the benefit of Japanese Patent
Application No. 2013-049101 filed Mar. 12, 2013, which is hereby
incorporated by reference herein in its entirety.
* * * * *