U.S. patent number RE47,829 [Application Number 15/905,476] was granted by the patent office on 2020-01-28 for image forming apparatus and light guide member.
This patent grant is currently assigned to KYOCERA Document Solutions Inc.. The grantee listed for this patent is KYOCERA Document Solutions Inc.. Invention is credited to Jun Nakai, Yoshinori Nakamura, Hironobu Oi, Yosuke Saito.
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United States Patent |
RE47,829 |
Saito , et al. |
January 28, 2020 |
Image forming apparatus and light guide member
Abstract
A light guide member has a transmitting/reflecting portion
transmitting and reflecting light that is emitted from a light
source, to enter one end of the light guide member in a
longitudinal direction, and be guided to the other end of the light
guide member so that the light is applied to: a position between
the developing roller and the transfer roller on the image carrier
on a downstream side in the traveling direction of the transfer
target member; and a position between the transfer roller and the
cleaning portion on the image carrier on an upstream side in the
traveling direction of the transfer target member. Furthermore, the
light guide member has a convex portion having an arc-shaped cross
section and being formed outward at a position opposing the
transmitting/reflecting portion in a part of a predetermined
specific region at one end or both ends in the longitudinal
direction.
Inventors: |
Saito; Yosuke (Osaka,
JP), Oi; Hironobu (Osaka, JP), Nakai;
Jun (Osaka, JP), Nakamura; Yoshinori (Osaka,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
KYOCERA Document Solutions Inc. |
Osaka-shi, Osaka |
N/A |
JP |
|
|
Assignee: |
KYOCERA Document Solutions Inc.
(Osaka-shi, Osaka, JP)
|
Family
ID: |
56010092 |
Appl.
No.: |
15/905,476 |
Filed: |
February 26, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
14946650 |
Nov 19, 2015 |
9471026 |
Oct 18, 2016 |
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Foreign Application Priority Data
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Nov 21, 2014 [JP] |
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2014-236153 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03G
21/08 (20130101); G03G 21/08 (20130101) |
Current International
Class: |
G03G
21/00 (20060101); G03G 21/08 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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59228683 |
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Dec 1984 |
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JP |
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2003005535 |
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Jan 2003 |
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JP |
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2003295717 |
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Oct 2003 |
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JP |
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2011221405 |
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Nov 2011 |
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JP |
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2013113901 |
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Jun 2013 |
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JP |
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2015094836 |
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May 2015 |
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JP |
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Primary Examiner: Hughes; Deandra M
Attorney, Agent or Firm: Alleman Hall Creasman & Tuttle
LLP
Claims
The invention claimed is:
1. An image forming apparatus comprising: a plurality of image
carriers arranged along a traveling direction of a transfer target
member; a developing roller configured to develop an electrostatic
latent image formed on each image carrier as a toner image; a
transfer roller configured to transfer the toner image formed on
each image carrier onto the transfer target member; a cleaning
portion configured to clean each image carrier after the toner
image is transferred onto the transfer target member by the
transfer roller; a light source configured to emit light used to
discharge each image carrier; and an elongated light guide member
having a transmitting/reflecting portion and a convex portion, the
transmitting/reflecting portion transmitting and reflecting light
that is emitted from the light source, to enter one end of the
light guide member in a longitudinal direction, and be guided to
the other end of the light guide member so that the light is
applied to: a position between the developing roller and the
transfer roller on the image carrier on a downstream side in the
traveling direction of the transfer target member; and a position
between the transfer roller and the cleaning portion on the image
carrier on an upstream side in the traveling direction of the
transfer target member, the convex portion having an arc-shaped
cross section and being formed outward at a position opposing the
transmitting/reflecting portion in a part of a predetermined
specific region at one end or both ends in the longitudinal
direction, wherein the light guide member .[.is an elongated member
that.]. has one flat surface having a plurality of the
transmitting/reflecting portions.
2. The image forming apparatus according to claim 1, wherein the
specific region is a region that corresponds to a non-image
formation region of the image carrier.
3. The image forming apparatus according to claim 1, wherein the
light guide member .[.is an elongated member that.]. has one flat
surface having a plurality of the transmitting/reflecting portions
formed along the longitudinal direction at predetermined
intervals.
4. The image forming apparatus according to claim 3, wherein the
transmitting/reflecting portions are inclined surfaces that are
formed inwardly from the flat surface at a predetermined
inclination angle.
5. The image forming apparatus according to claim 3, wherein the
intervals of the transmitting/reflecting portions become shorter as
a distance from the light source becomes longer.
6. The image forming apparatus according to claim 3, wherein the
sizes of the transmitting/reflecting portions become larger as a
distance from the light source becomes longer.
7. The image forming apparatus according to claim 1, further
comprising a light-transmitting member that covers a part or the
entirety of an outer periphery of the light guide member.
8. The image forming apparatus according to claim 1, wherein the
image carrier disposed on a most upstream side in the traveling
direction is an image carrier for yellow; and the light source and
the light guide member are disposed only at positions on a
downstream side of each image carrier in the traveling
direction.
9. An elongated light guide member used in an image forming
apparatus including: a plurality of image carriers arranged along a
traveling direction of a transfer target member; a developing
roller configured to develop an electrostatic latent image formed
on each image carrier as a toner image; a transfer roller
configured to transfer the toner image formed on each image carrier
onto the transfer target member; a cleaning portion configured to
clean each image carrier after the toner image is transferred onto
the transfer target member by the transfer roller; and a light
source configured to emit light used to discharge each image
carrier, the light guide member having a transmitting/reflecting
portion and a convex portion, the transmitting/reflecting portion
transmitting and reflecting light that is emitted from the light
source, to enter one end of the light guide member in a
longitudinal direction, and be guided to the other end of the light
guide member so that the light is applied to: a position between
the developing roller and the transfer roller on the image carrier
on a downstream side in the traveling direction of the transfer
target member; and a position between the transfer roller and the
cleaning portion on the image carrier on an upstream side in the
traveling direction of the transfer target member, the convex
portion having an arc-shaped cross section and being formed outward
at a position opposing the transmitting/reflecting portion in a
part of a predetermined specific region at one end or both ends in
the longitudinal direction, the light guide member .[.being an
elongated member that has.]. .Iadd.having .Iaddend.one flat surface
.[.having.]. .Iadd.with .Iaddend.a plurality of the
transmitting/reflecting portions.
.Iadd.10. An image forming apparatus comprising: a plurality of
image carriers arranged along a traveling direction of a transfer
target member; a developing roller configured to develop an
electrostatic latent image formed on each image carrier as a toner
image; a transfer roller configured to transfer the toner image
formed on each image carrier onto the transfer target member; a
cleaning portion configured to clean each image carrier after the
toner image is transferred onto the transfer target member by the
transfer roller; a light source configured to emit light used to
discharge each image carrier; and an elongated light guide member
having a transmitting/reflecting portion, the
transmitting/reflecting portion transmitting and reflecting light
that is emitted from the light source, to enter one end of the
light guide member in a longitudinal direction, and be guided to
the other end of the light guide member so that the light is
applied to: a position between the developing roller and the
transfer roller on the image carrier on a downstream side in the
traveling direction of the transfer target member; and a position
between the transfer roller and the cleaning portion on the image
carrier on an upstream side in the traveling direction of the
transfer target member, wherein the light guide member has one flat
surface having a plurality of the transmitting/reflecting
portions..Iaddend.
.Iadd.11. An elongated light guide member used in an image forming
apparatus including: a plurality of image carriers arranged along a
traveling direction of a transfer target member; a developing
roller configured to develop an electrostatic latent image formed
on each image carrier as a toner image; a transfer roller
configured to transfer the toner image formed on each image carrier
onto the transfer target member; a cleaning portion configured to
clean each image carrier after the toner image is transferred onto
the transfer target member by the transfer roller; and a light
source configured to emit light used to discharge each image
carrier, the light guide member having a transmitting/reflecting
portion, the transmitting/reflecting portion transmitting and
reflecting light that is emitted from the light source, to enter
one end of the light guide member in a longitudinal direction, and
be guided to the other end of the light guide member so that the
light is applied to: a position between the developing roller and
the transfer roller on the image carrier on a downstream side in
the traveling direction of the transfer target member; and a
position between the transfer roller and the cleaning portion on
the image carrier on an upstream side in the traveling direction of
the transfer target member, the light guide member having one flat
surface with a plurality of the transmitting/reflecting
portions..Iaddend.
.Iadd.12. An image forming unit comprising: a first image carrier;
a developing roller configured to develop an electrostatic latent
image formed on the first image carrier as a toner image; a first
transfer roller configured to transfer the toner image formed on
the first image carrier onto a transfer target member; a cleaning
portion configured to clean the first image carrier after the toner
image is transferred onto the transfer target member by the first
transfer roller; a light source configured to emit light used to
discharge the first image carrier; and an elongated light guide
member having a transmitting/reflecting portion, the
transmitting/reflecting portion transmitting and reflecting light
that is emitted from the light source, to enter one end of the
light guide member in a longitudinal direction, and be guided to
the other end of the light guide member so that the light is
applied to: a position between the developing roller and the first
transfer roller on the first image carrier; and a position between
a second transfer roller and a second cleaning portion on a second
image carrier of another image forming unit disposed on an upstream
side in a traveling direction of the transfer target member, the
light guide member having one flat surface with a plurality of the
transmitting/reflecting portions..Iaddend.
Description
INCORPORATION BY REFERENCE
This application is based upon and claims the benefit of priority
from the corresponding Japanese Patent Application No. 2014-236153
filed on Nov. 21, 2014, the entire contents of which are
incorporated herein by reference.
BACKGROUND
The present disclosure relates to an electrophotographic image
forming apparatus and a light guide member used in the
electrophotographic image forming apparatus.
In an electrophotographic image forming apparatus, a photosensitive
drum is uniformly charged by a charging roller. Next, laser light
is applied to a surface of the charged photosensitive drum, and
thus an electrostatic latent image is formed on the surface of the
photosensitive drum. Then, the electrostatic latent image on the
photosensitive drum is developed by using toner. Then, after the
toner image on the photosensitive drum is transferred onto a
transfer target member such as a sheet or an intermediate transfer
belt, the photosensitive drum is discharged by discharging light
emitted from a discharging portion, and the surface of the
photosensitive drum is cleaned by a cleaning portion.
In some cases, a discharging portion, which applies discharging
light to the photosensitive drum before transfer of the toner image
on the photosensitive drum onto the transfer target member, is
provided. Furthermore, an arrangement is known in which light
emitted from a light source is reflected, by a light guide member
having two reflection surfaces, toward: a position at which a toner
image has been transferred and which is a position of a
photosensitive drum on an upstream side in a traveling direction of
the transfer target member; and a position at which a toner image
has not been transferred and which is a position of a
photosensitive drum on a downstream side in the traveling direction
of the transfer target member.
SUMMARY
An image forming apparatus according to one aspect of the present
disclosure includes: a plurality of image carriers; a developing
roller; a transfer roller; a cleaning portion; a light source; and
a light guide member. The image carriers are arranged along a
traveling direction of a transfer target member. The developing
roller develops an electrostatic latent image formed on each image
carrier as an toner image. The transfer roller transfers the toner
image formed on each image carrier onto the transfer target member.
The cleaning portion cleans each image carrier after the toner
image is transferred onto the transfer target member by the
transfer roller. The light source emits light used to discharge
each image carrier. The light guide member has a
transmitting/reflecting portion transmitting and reflecting light
that is emitted from the light source, to enter one end of the
light guide member in a longitudinal direction, and be guided to
the other end of the light guide member so that the light is
applied to: a position between the developing roller and the
transfer roller on the image carrier on a downstream side in the
traveling direction of the transfer target member; and a position
between the transfer roller and the cleaning portion on the image
carrier on an upstream side in the traveling direction of the
transfer target member. Furthermore, the light guide member has a
convex portion having an arc-shaped cross section and being formed
outward at a position opposing the transmitting/reflecting portion
in a part of a predetermined specific region at one end or both
ends in the longitudinal direction.
A light guide member according to another aspect of the present
disclosure is an elongated member used in an image forming
apparatus including: a plurality of image carriers arranged along a
traveling direction of a transfer target member; a developing
roller configured to develop an electrostatic latent image formed
on each image carrier as a toner image; a transfer roller
configured to transfer the toner image formed on each image carrier
onto the transfer target member; a cleaning portion configured to
clean each image carrier after the toner image is transferred onto
the transfer target member by the transfer roller; and a light
source configured to emit light used to discharge each image
carrier. The light guide member has a transmitting/reflecting
portion and a convex portion, the transmitting/reflecting portion
transmitting and reflecting light that is emitted from the light
source, to enter one end of the light guide member in a
longitudinal direction, and be guided to the other end of the light
guide member so that the light is applied to: a position between
the developing roller and the transfer roller on the image carrier
on a downstream side in the traveling direction of the transfer
target member; and a position between the transfer roller and the
cleaning portion on the image carrier on an upstream side in the
traveling direction of the transfer target member, the convex
portion having an arc-shaped cross section and being formed outward
at a position opposing the transmitting/reflecting portion in a
part of a predetermined specific region at one end or both ends in
the longitudinal direction.
This Summary is provided to introduce a selection of concepts in a
simplified form that are further described below in the Detailed
Description with reference where appropriate to the accompanying
drawings. This Summary is not intended to identify key features or
essential features of the claimed subject matter, nor is it
intended to be used to limit the scope of the claimed subject
matter. Furthermore, the claimed subject matter is not limited to
implementations that solve any or all disadvantages noted in any
part of this disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram illustrating a configuration of an image
forming apparatus according to an embodiment of the present
disclosure.
FIG. 2 is a diagram illustrating an example of image forming units
of the image forming apparatus illustrated in FIG. 1.
FIG. 3 is a diagram illustrating a discharging portion of the image
forming unit illustrated in FIG. 2.
FIG. 4 is a diagram illustrating a light guide member of the
discharging portion illustrated in FIG. 3.
DETAILED DESCRIPTION
Hereinafter, for understanding of the present disclosure, an
embodiment of the present disclosure will be described based on the
drawings. Note that the embodiment below is a specific exampe of
the present disclosure and does not limit the technical scope of
the present disclosure.
As iustrated in FIG. 1, an image forming apparatus 10 includes a
plurality of image forming units 1 to 4, an intermediate transfer
belt 5, a laser scanning unit 6, a secondary transfer roller 7, a
fixing device 8, a sheet discharge tray 9, toner containers 21 to
24, a sheet feeding cassette 31, and a conveyance path 32. The
image forming apparatus 10 is a color printer that forms a color
image or a monochrome image based on image data inputted from an
information processing apparatus such as a personal computer on a
sheet supplied along the conveyance path 32 from the sheet feeding
cassette 31.
The image forming units 1 to 4 are arranged along a traveling
direction D1 of the intermediate transfer belt 5 and constitute a
so-called tandem type image forming portion. Specifically, the
image forming unit 1 forms a Y (yellow) toner image, the image
forming unit 2 forms an M (magenta) toner image, the image forming
unit 3 forms a C (cyan) toner image, and the image forming unit 4
forms a K (black) toner image. In the present embodiment, the
intermediate transfer belt 5 is described as an example of a
transfer target member, but a sheet such as a printing sheet may be
an example of a transfer target member. That is, an arrangement in
which a toner image is transferred onto a sheet conveyed by a sheet
conveyor belt is possible as another embodiment.
As illustrated in FIG. 2, the image forming unit 1 and the image
forming unit 2 are electrophotographic image forming units each
including a photosensitive drum 11, and a charging portion 12, a
developing portion 13, a discharging portion 14, a primary transfer
roller 15, and a cleaning device 16 that correspond to the
photosensitive drum 11. Note that the image forming unit 3 and the
image forming unit 4 have a similar configuration, and therefore
description thereof is omitted.
Each of the photosensitive drums 11 is arranged along the traveling
direction of the intermediate transfer belt 5 and is an image
carrier that carries an electrostatic latent image and a toner
image. Each of the charging portions 12 has a charging roller 121
that charges the photosensitive drum 11 by electric power supplied
from a power source (not shown). Next, laser light by the laser
scanning unit 6 is applied to the photosensitive drum 11 charged by
the charging portion 12, and thus an electrostatic latent image
based on image data is formed on an outer peripheral surface of the
photosensitive drum 11. Each of the developing portions 13 has a
developing roller 131 that develops the electrostatic latent image
formed on the photosensitive drum 11 by using toner (developer).
Note that an external additive such as a lubricating agent or a
polishing agent is used together with toner to develop the
electrostatic latent image by the developing portion 13. Toner is
supplied from the detachable toner containers 21 to 24
corresponding to the respective colors to the respective developing
portions 13.
Each of the primary transfer rollers 15 transfers the toner image
formed on the photosensitive drum 11 onto the intermediate transfer
belt 5. The intermediate transfer belt 5 is an intermediate
transfer member that travels on the photosensitive drums 11 of the
respective image forming units 1 to 4 and on which toner images of
the respective colors formed on the respective photosensitive drums
11 are sequentially transferred so as to overlap each other. Then,
the toner image on the intermediate transfer belts 5 is transferred
onto a sheet conveyed via the conveyance path 32 from the sheet
feeding cassette 31 by the secondary transfer roller 7. Then, the
toner image transferred onto the sheet is heated by the fixing
device 8 so as to be fused and fixed on the sheet. Each of the
cleaning devices 16 has a cleaning portion 161 such as a cleaning
roller or a cleaning blade that cleans the photosensitive drum 11
after the toner image is transferred onto the intermediate transfer
belt 5 by the primary transfer roller 15.
Each of the discharging portions 14 applies discharging light L1
for discharging the photosensitive drum 11 to a position between
the primary transfer roller 15 and the cleaning portion 161 on an
outer peripheral surface of the photosensitive drum 11 on an
upstream side of the traveling direction D1 of the intermediate
transfer belt 5. In other words, each of the discharging portions
14 applies the discharging light L1 to a position that is, in a
rotation direction of the photosensitive drum 11, on a downstream
side of the primary transfer roller 15 and on an upstream side of
the cleaning portion 161. Furthermore, each of the discharging
portions 14 applies discharging light L2 for discharging the
photosensitive drum 11 to a position between the developing roller
131 and the primary transfer roller 15 on an outer peripheral
surface of the photosensitive drum 11 on a downstream side of the
traveling direction D1 of the intermediate transfer belt 5. In
other words, each of the discharging portions 14 applies the
discharging light L2 to a position that is, in the rotation
direction of the photosensitive drum 11, on a downstream side of
the developing roller 131 and on an upstream side of the primary
transfer roller 15. A so-called memory image of the photosensitive
drum 11 is suppressed by discharging the photosensitive drum 11
before and after transfer of the toner image of the photosensitive
drum 11 onto the intermediate transfer belt 5.
Since a yellow image is not noticeable, the problem of occurrence
of an image memory hardly become evident even if the discharging
light L2 is not applied to the photosensitive drum 11 of the image
forming unit 1 that corresponds to yellow. Therefore, in the image
forming apparatus 10, a discharging portion 14 that applies
discharging light L2 to the photosensitive drum 11 of the image
forming unit 1 is omitted. That is, in the image forming apparatus
10, the photosensitive drum 11 disposed on the most upstream side
of the traveling direction D1 is one that corresponds to yellow,
and the discharging portion 14 including a light source 141 and a
light guide member 142 is disposed only at positions on the
downstream side of the respective photosensitive drums 11 in the
traveling direction D1. Needless to say, it is possible to employ
an arrangement in which the image forming apparatus 10 includes a
discharging portion 14 that applies the discharging light L2 to the
photosensitive drum 11 of the image forming unit 1.
Next, the discharging portion 14 is described with reference to
FIGS. 3 and 4.
The discharging portion 14 is disposed between the photosensitive
drum 11 disposed on the upstream side in the traveling direction D1
of the intermediate transfer belt 5 and the photosensitive drum 11
disposed on the downstream side in the traveling direction D1 of
the intermediate transfer belt 5. The discharging portion 14 has
the light source 141 and the light guide member 142 elongated in an
axial direction D2 of the photosensitive drum 11. The light guide
member 142 is longer than the photosensitive drum 11, and the
longitudinal direction of the light guide member 142 is parallel
with the axial direction D2 of the photosensitive drum 11.
The light source 141 is, for example, an LED light source that
emits light for discharging the photosensitive drum 11. The light
emitted from the light source 141 enters a light incident surface
143 formed at one end of the light guide member 142 in the
longitudinal direction. In the light guide member 142, the light
that enters from the one end at which the light incident surface
143 is formed is guided toward an end surface 144 at the other end
while being repeatedly reflected. In the present embodiment, a case
where the light source 141 is provided at one end of the light
guide member 142 is described as an example. However, an
arrangement in which the light source 141 is provided at both ends
of the light guide member 142 and light enters from both of the
light incident surface 143 and the end surface 144 is also possible
as another embodiment.
The light guide member 142 is a substantially cylindrical shaped
member whose cross section has a D-shape (semicircular shape) and
that has a flat surface 145 and a curved surface 146 and is, for
example, made of a material such as a resin.
A plurality of transmitting/reflecting portions 147 are formed on
the flat surface 145 at predetermined intervals in the longitudinal
direction.
Specifically, the transmitting/reflecting portions 147 are inclined
surfaces formed inwardly from the flat surface 145 at a
predetermined inclination angle. The inclination angle of the
transmitting/reflecting portions 147 is appropriately determined so
that the amount of transmission and the amount of reflection of the
light emitted from the light source 141 in the
transmitting/reflecting portions 147 have a predetermined
relationship. For example, the inclination angle of the
transmitting/reflecting portions 147 is determined so that a ratio
of the amount of discharging light L1 that reaches the
photosensitive drum 11 on the upstream side in the traveling
direction D1 of the intermediate transfer belt 5 and the amount of
discharging light L2 that reaches the photosensitive drum 11 on the
downstream side in the traveling direction D1 of the intermediate
transfer belt 5 becomes 1:10.
In the discharging portion 14, the light emitted from the light
source 141 is reflected by the transmitting/reflecting portions
147. This causes the light to be applied as the discharging light
L1 for discharging the photosensitive drum 11 to the position
between the primary transfer roller 15 and the cleaning device 16
on the outer peripheral surface of the photosensitive drum 11 on
the upstream side in the traveling direction D1 of the intermediate
transfer belt 5.
In the discharging portion 14, the light emitted from the light
source 141 passes through the transmitting/reflecting portions 147.
This causes the light to be applied as the discharging light L2 for
discharging the photosensitive drum 11 to the position between the
developing roller 131 and the primary transfer roller 15 on the
outer peripheral surface of the photosensitive drum 11 on the
downstream side in the traveling direction D1 of the intermediate
transfer belt 5.
Meanwhile, the arrangement in which a light guide member has two
reflection surfaces as in the related art described above has a
problem that the shape of a metal mold for formaion of the light
guide member becomes complicated. However, the image forming
apparatus 10 makes it possible to simplify the shape of a metal
mold for molding the light guide member 142 since only the one flat
surface 145 having the transmitting/reflecting portions 147 is
formed in the light guide member 142.
Note that the light guide member 142 may be roated by 180 degrees.
That is, the discharging portion 14 may be arranged such that the
light emitted from the light source 141 is reflected by the
transmitting/reflecting portions 147 so as to be applied as the
discharging light L2 to the position between the developing roller
131 and the primary transfer roller 15 on the outer peripheral
surface of the photosensitive drum 11 on the downstream side in the
traveling direction D1 of the intermediate transfer belt 5. In this
case, the discharging portion 14 is arranged such that the light
emitted from the light source 141 passes through the
transmitting/reflecting portions 147 so as to be applied as the
discharging light L1 to the position between the primary transfer
roller 15 and the cleaning device 16 on the outer peripheral
surface of the photosensitive drum 11 on the upstream side in the
traveling direction D1 of the intermediate transfer belt 5.
In the light guide member 142, the amount of light gradually
declines while the light incident from the light source 141 is
guided from one end to the other end. Accordingly, in the light
guide member 142, intervals P1 at which the transmitting/reflecting
portions 147 are formed in the longitudinal direction become
shorter as the distance from the light source 141 becomes longer.
This increases the amount of reflection and the amount of
transmission of the light by the transmitting/reflecting portions
147 at positions far from the light incident surface 143 of the
light guide member 142, thereby achieving uniformity of the
discharging light L1 and the discharging light L2 in the
longitudinal direction of the light guide member 142. Furthermore,
an arrangement in which the sizes of the transmitting/reflecting
portions 147 become larger as the distance from the light source
141 becomes longer may be employed as an arrangement for achieving
uniformity of the discharging light L1 and the discharging light L2
emitted from the light guide member 142.
In a case where the amount of discharging light that is applied
from the vicinity of the end of the light guide member 142 on the
light source 141 side to an image formation region A1 of the
photosensitive drum 11 on the downstream side in the traveling
direction D1 of the intermediate transfer belt 5 is insufficient,
there is a risk of inhibiting uniformity of the discharging light.
Specifically, in the light guide member 142, the discharging light
L2 that has passed through the transmitting/reflecting portions 147
is applied to the photosensitive drum 11 at a certain angle. This
may undesirably cause the amount of light to be applied to an end
portion of the image formation region A1 of the photosensitive drum
11 to be smaller than that in the other region.
Furthermore, in a case where discharging light of a high intensity
is applied from the vicinity of the end of the light guide member
142 on the light source 141 side to the image formation region A1
of the photosensitive drum 11 on the upstream side in the traveling
direction D1, there is a risk of inhibiting uniformity of the
discharging light. Specifically, in a case where light of a high
intensity is applied from a position in the vicinity of the light
source 141 on the curved surface 146 of the light guide member 142
and reaches the image formation region A1 of the photosensitive
drum 11 on the upstream side in the traveling direction D1 of the
intermediate transfer belt 5, there is a risk of inhibiting
uniformity of the amount of discharge of the image formation region
A1.
In view of this, the light guide member 142 has a light diffusing
portion 148 at a position corresponding to a non-image formation
region A2 that is outside of the image formation region A1 of the
photosensitive drum 11. The light diffusing portion 148 is a convex
portion having an arc-shaped cross section and being formed
outward, and is formed on the opposing the transmitting/reflecting
portions 147 in a part of a predetermined specific region
corresponding to the non-image formation region A2 at one end or
both ends of the light guide member 142 in the longitudinal
direction. For example, the light diffusing portion 148 has a
hemispherical shape. The light diffusing portion 148 may have a
shape obtained by cutting a part of a sphere or a spheroid.
With the arrangement, light reflected by the light diffusing
portion 148 of the light guide member 142 is applied as the
discharging light L2 from the flat surface 145 to the end of the
image formation region A1 of the photosensitive drum 11 on the
downstream side in the traveling direction D1 of the intermediate
transfer belt 5. It is therefore possible to compensate for the
insufficiency of the amount of light at the end of the image
formation region A1 of the photosensitive drum 11 on the downstream
side in the traveling direction D1 of the intermediate transfer
belt 5, thereby uniforming the amount of discharge.
Furthermore, since light that passes through the curved surface 146
from the light guide member 142 is diffused by the light diffusing
portion 148, the amount of light that reaches, as the discharging
light L1, the image formation region A2 of the photosensitive drum
11 on the upstream side of the traveling direction D1 in the
intermediate transfer belt 5 is suppressed. It is therefore
possible to uniform the amount of discharging light applied to the
image formation region A1 of the photosensitive drum 11 on the
upstream side in the traveling direction D1 of the intermediate
transfer belt 5.
As illustrated in FIG. 2, a transparent or semi-transparent
light-transmitting member 17 is provided as a cover member that
covers a part or the entirety of the light source 141 and the light
guide member 142 of the discharging portion 14. This prevents dust
or toner from attaching to the light source 141 and the light guide
member 142 of the discharging portion 14, thereby making it
possible to prolong the life time of the image forming apparatus
10.
It is to be understood that the embodiments herein are illustrative
and not restrictive, since the scope of the disclosure is defined
by the appended claims rather than by the description preceding
them, and all changes that fall within metes and bounds of the
claims, or equivalence of such metes and bounds thereof are
therefore intended to be embraced by the claims.
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