U.S. patent application number 11/550540 was filed with the patent office on 2007-06-07 for image forming apparatus.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Shin-ichi SUGIYAMA.
Application Number | 20070125595 11/550540 |
Document ID | / |
Family ID | 38117602 |
Filed Date | 2007-06-07 |
United States Patent
Application |
20070125595 |
Kind Code |
A1 |
SUGIYAMA; Shin-ichi |
June 7, 2007 |
IMAGE FORMING APPARATUS
Abstract
An image forming apparatus has an actuation portion emitting an
actuation sound and an internal part provided away from and opposed
to the actuation portion. Further the image forming apparatus has a
sound absorbing member formed of a foam metal, and provided away
from the internal part between the actuation portion and the
internal part.
Inventors: |
SUGIYAMA; Shin-ichi;
(Kashiwa-shi, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
38117602 |
Appl. No.: |
11/550540 |
Filed: |
October 18, 2006 |
Current U.S.
Class: |
181/284 |
Current CPC
Class: |
G03G 21/00 20130101 |
Class at
Publication: |
181/284 |
International
Class: |
E04B 1/82 20060101
E04B001/82 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 2, 2005 |
JP |
2005-349847 |
Claims
1. An image forming apparatus comprising: an internal part away
from a wall of a housing inward of the apparatus; an actuation
portion emitting an actuation sound and provided outside said
housing; and a sound absorbing member formed of a foam metal and
provided in an opening portion, which is provided in said wall
between said internal part and said actuation portion.
2. An image forming apparatus according to claim 1, wherein a
porosity of said foam metal is 50% or more.
3. An image forming apparatus according to claim 1, wherein a space
between said internal part and said sound absorbing member is set
to substantially one fourth of a wavelength of the actuation
sound.
4. An image forming apparatus according to claim 1, wherein said
sound absorbing member is formed of aluminum.
5. An image forming apparatus according to claim 1, wherein a space
between said internal part and said sound absorbing member is set
to 20 mm.
6. An image forming apparatus according to claim 1, wherein said
actuation portion comprises a pickup roller lifting and lowering to
feed a sheet supported on a tray and said internal part is a
component constituting the image forming apparatus for forming an
image on a sheet.
7. An image forming apparatus comprising: an actuation portion
emitting an actuation sound, provided inside a housing and opposed
to an opening portion formed in a wall of said housing; an internal
part provided in an inner part of said housing, opposed to and away
from said actuation portion; and a sound absorbing member formed of
a foam metal, provided between said actuation portion and said
internal part, and away from said internal part.
8. An image forming apparatus according to claim 7, wherein a
porosity of said foam metal is 50% or more.
9. An image forming apparatus according to claim 7, wherein a space
between said internal part and said sound absorbing member is set
to substantially one fourth of a wavelength of the actuation
sound.
10. An image forming apparatus according to claim 7, wherein said
sound absorbing member is formed of aluminum.
11. An image forming apparatus according to claim 7, wherein a
space between said internal part and said sound absorbing member is
set to 20 mm.
12. An image forming apparatus comprising: an actuation portion
emitting an actuation sound; an internal part provided away from
and opposed to said actuation portion, wherein said internal part
is a component constituting an image forming portion for forming an
image on a sheet; and a sound absorbing member formed of a foam
metal, provided between said actuation portion and said internal
part, and away from said internal part.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an image forming apparatus
such as a copy machine and an LBP (laser beam printer),
particularly an image forming apparatus to attenuate echo of
actuation sound of an actuation portion of the apparatus.
[0003] 2. Description of the Related Art
[0004] Conventionally, as a countermeasure against noise of the
image forming apparatus, it has been considered how to reduce the
actuation sound, with regard to the actuation portion (sound
source) such as motor, solenoid, and roller, which emits the
actuation sound or noise. And it has been considered how to muffle
the noise by sealing the actuation portion (Japanese Patent
Application Laid-Open No. 2002-307780). Further it has been
considered to provide the sound absorbing material near the
actuation portion (Japanese Patent Application Laid-Open No.
H03-2063).
[0005] However, the actuation portion of the image forming
apparatus includes a manual sheet feed portion, a movable tray of a
sheet discharge portion, and so on, which are disposed outside the
housing of the image forming apparatus and are not sealed
completely. With regard to the actuation sound of these actuation
portions transmits to a person with aggregate sum of the sound
directly emitted from an unsealed opening and the sound reflected
from exterior walls around the actuation portion and emitted from
the opening. There is a structure of applying a small amount of
sound absorbing member on the exterior wall to attenuate the
reflected sound. As the sound absorbing member, porous members such
as polyurethane foam and inorganic fiber such as glass wool have
been widely employed.
[0006] An aluminum has been employed to absorb sound (Japanese
Patent Application Laid-Open No. 2002-244403). Foam metal also has
been employed to absorb sound (Japanese Patent Publication No.
H05-9036).
[0007] However, the conventional image forming apparatus has had a
problem of little effect of absorbing reflected sound. That is, the
center frequency of the actuation sound of the actuation portion
which is difficult to seal is mainly not more than 1 kHz, while the
sound absorbing members of porous members such as polyurethane or
inorganic fiber sound absorbing members are effective against a
frequency band of not less than 1 kHz. Therefore, the conventional
reflected sound attenuation mechanism has not been suitable for low
frequency.
[0008] Further, for example, in the case that a sound absorption
degree of not less than 0.8 at a noise center frequency of 500 Hz
is achieved, a thickness of the sound absorbing member is required
to range from about 50 mm to about 100 mm. For this reason, in the
conventional apparatus, it has been difficult to employ the sound
absorbing member for the image forming apparatus, because it
requires a large space for applying the member. If the sound
absorbing member is used, this poses the problem of making the
image forming apparatus lager in size.
[0009] Although the above explanation is related to the problem
with the actuation portion disposed outside the housing, there has
been also the same problem with the actuation portion disposed
inside the housing and opposed to an opening portion of the
housing. That is, there has been a problem in which the actuation
sound of the actuation portion is reflected by the internal part of
the housing to leak as noise from the opening portion of the
housing to outside.
SUMMARY OF THE INVENTION
[0010] It is an object of the present invention to provide an image
forming apparatus to enhance effect of reducing reflected actuation
sound of an actuation portion.
[0011] The image forming apparatus of the present invention
includes: an internal part away from a wall of a housing inward of
the apparatus; and an actuation portion emitting an actuation sound
and provided outside the housing, wherein an opening portion is
provided in the wall between the internal part and the actuation
portion and a sound absorbing member formed of foam metal is
provided in the opening portion.
[0012] Also, an image forming apparatus of the present invention
includes: an actuation portion emitting an actuation sound and
disposed, in a housing, opposite to an opening formed in a wall of
the housing; an internal part disposed, in an inner part of the
housing, opposite to the actuation portion and away from the
actuation portion; and a sound absorbing member formed of foam
metal, provided between the actuation portion and the internal part
and away from the internal part.
[0013] Also, an image forming apparatus of the present invention
includes: an actuation portion emitting an actuation sound; an
internal part disposed opposite to the actuation portion and away
from the actuation portion, wherein the internal part is a part
constituting an image forming portion to form an image on a sheet;
and a sound absorbing member formed of foam metal, provided between
the actuation portion and the internal part and away from the
internal part.
[0014] In the image forming apparatus of the present invention, a
space is formed between the sound absorbing member made of foam
metal and the internal part. Therefore, the actuation sound of the
actuation portion can be attenuated not only by the foam metal but
also the space.
BRIEF DESCRIPTION OF THE DRAWING
[0015] FIG. 1 is an enlarged view showing a reflected sound
reduction structure in an image forming apparatus according to an
embodiment of the present invention.
[0016] FIG. 2 is a right side view of FIG. 1.
[0017] FIG. 3 is an illustration explaining the reflected sound
reduction structure in the case of propagating sound waves in a
direction of plate thickness of a foam metal plate.
[0018] FIG. 4 is a graph comparing sound absorption performances of
the foam metal plates and those of the other sound absorbing
members.
[0019] FIG. 5 is a schematic block diagram explaining the sound
absorption principle of the foam metal plate.
[0020] FIG. 6 is a front sectional view showing a schematic
construction of the image forming apparatus according to the
embodiment of the present invention.
[0021] FIG. 7 is an enlarged view of other reflected sound
reduction structure provided in the image forming apparatus
according to the embodiment of the present invention.
[0022] FIG. 8 is a graph showing a relation between the space
behind the foam metal plate and the sound absorption degree.
[0023] FIG. 9 is a graph showing the sound absorption performances
of the other foam metal plates.
DESCRIPTION OF THE EMBODIMENTS
[0024] An image forming apparatus of an embodiment of the present
invention will be described hereinafter with reference to the
drawings. Numerical values employed in the embodiments of the
present invention are reference values and do not necessarily limit
the present invention.
[0025] FIG. 6 is a cross-sectional front view showing a schematic
construction of the image forming apparatus according to the
embodiment of the present invention.
[0026] In the image forming apparatus 20, an image of an original
is read by an image reading portion 8, an electrostatic latent
image is formed on a surface of a photosensitive drum 1 as a latent
image bearing member by an exposure from an image writing portion 9
in accordance with a command from a controller (now shown) based on
the read image data. The surface of the photosensitive drum 1 is
uniformly charged to a predetermined potential before the exposure
by a charger 2. An electrostatic latent image is formed on the
photosensitive drum 1 by a laser beam or the like irradiated on the
uniformly charged surface of the photosensitive drum 1 from the
image writing portion 9. The electrostatic latent image formed on
the photosensitive drum 1 is toner-developed with toner as a
developer by a developing device 3 to form a toner image. And then
the developed toner image is conveyed to a portion opposed to a
transfer device 4 by the rotation of the photosensitive drum 1.
[0027] In accordance with the conveyance of the developed toner
image, a pickup roller 51 of a manual sheet feed unit 5 feeds a
sheet S as a recording medium one-by-one from a sheet tray 25. The
sheet is timely conveyed to between the photosensitive drum 1 and
the transfer device 4 by a pair of registration rollers 6. And
while the sheet S is passing through between the photosensitive
drum 1 and the transfer device 4, the transfer device 4 transfers
the toner image on the photosensitive drum 1 to the sheet S. The
sheet is also fed from a cassette 13 so that the toner image is
transferred on the sheet.
[0028] The sheet S on which the toner image is transferred is
conveyed to a fixing device 7 by a conveying device 12. The fixing
device 7 nips the sheet while heating the sheet. The fixing device
7 is heated by a heater (not shown) provided in a fixing roller of
the fixing device 7 to fuse the toner image on the sheet S to fix
the toner image to the sheet S. And then, the sheet S on which the
toner image is fixed is discharged to a tray 11 outside a housing
21 by a pair of discharging rollers 10. In this way, a series of
the image forming processes in the image forming apparatus is
completed.
[0029] Next, a reflected sound reduction structure will be
described with reference to FIGS. 1 and 2.
[0030] FIG. 1 is an enlarged view of the reflected sound reduction
structure 24 in FIG. 6. The manual sheet feed unit 5 constitutes a
part of an exterior wall 22 of the housing 21. The manual sheet
feed unit 5 comprises a pickup roller 51, a pickup support plate 52
rotatably axially supporting the pickup roller 51 to bring the
pickup roller 51 into and out of contact with the sheet S, a
receptive stopper 53 to determine a rising position of the pickup
supporting plate 52. When the pickup support plate 52 is raised,
the pickup roller 51 is separated from the sheet S. A manual sheet
feed cover 54 of the sheet feed unit 5 and the receptive stopper 53
are integrally formed with ABS resin material and applied with
coating for an exterior part.
[0031] FIG. 2 is a right side view of FIG. 1. An opening portion 57
is formed in the center of the exterior wall of the manual sheet
feed cover 54 near the receptive stopper 53. The opening portion 57
is provided with a foam metal plate 55 having air-permeability
porous member so as to close the opening portion 57. The foam metal
plate 55 as a sound absorption material is also applied with
coating for an exterior part. The foam metal plate 55 is fixed to
the manual sheet feed cover 54 with screws 56 at both lateral ends
which are boring processed. Between a foam metal plate 55 and a
reflection wall 3a opposed to the foam metal plate 55 of the
developing device 3, a below-mentioned predetermined distance is
spaced to form a space 69. This space 69 is a space for attenuating
sound. A sheet supply port 26 supplying sheets stacked in the
manual sheet feed tray 25 is formed below the foam metal plate
55.
[0032] With the above configuration, when the pickup support plate
52 is raised by a solenoid 98, the pickup support plate 52 is
brought into contact with a surface of receptive stopper 53 to
produce collision noise. The pickup roller 51, the pickup support
plate 52, and the receptive stopper 53 are an actuation portion
emitting actuation sound.
[0033] The collision noise is radially propagated in air. When
there is a wall near the pickup support plate 52 and the receptive
stopper 53 as a sound source, the collision noise is reflected by
the wall so that a sound pressure in an open space opposed to the
wall surface is increased. The foam metal plate 55 is located on
the left side of the pickup support plate 52 and the receptive
stopper 53. This foam metal plate 55 dramatically reduces the
reflected sound. Especially, when a line connecting the opening
portion 57 and the actuation portion as a sound source is
perpendicular to one side surface (the reflection surface 3a in
this case) of the developing device 3, there is a strong
possibility that the sound from the actuation portion is reflected
by the reflection surface 3a to leak from the opening portion.
However, in the embodiment of the present invention, since the foam
metal plate 55 is located between the actuation portion and
developing device 3, the reflected sound is reduced by the sound
absorption effect of the foam metal plate 55.
[0034] Here, a sound absorption mechanism of the foam metal plate
55 will be described. FIG. 3 shows a reflected sound reduction
structure 44 when the sound waves are propagated in a direction of
plate thickness of the foam metal plate 55. Cells 62 independently
formed (black portion in FIG. 3) are communicated with each other
by through-holes 64 formed by extending through the foam metal
plate 55. The sound waves 66 are diffusely reflected by a metal
shell 63 of the cell 62 exposed on the surface to be
interference-attenuated by reflected waves. And a part of the sound
waves 66 passes through the thorough-holes 64. The passed sound
waves are expanded and attenuated within a next cell 62, and
likewise, the sound waves are repeatedly expanded and attenuated
every time the sound waves move to an adjacent cell. And when the
sound waves arrive at the opposite side of the foam metal plate 55,
the sound waves are reflected by the reflection wall 3a, which is a
predetermined distance away from the foam metal plate 55 through
the space 69, to be made into reflected waves 81, thereby the noise
is reduced by the interference, expansion, and friction with the
metal shells (cell wall surfaces) 63.
[0035] FIG. 4 is a graph showing a comparison of sound absorption
performance between the foam metal plates 55 and other sound
absorbing members. In FIG. 4, absorption members in the graph
represented by reference signs (a), (b), and (c) are foam metal A
having a plate thickness of 10 mm. A sound absorbing member
represented by a sign (d) is a glass wool (plate thickness: 25 mm).
A sound absorbing member represented by a sign (e) is a urethane
(plate thickness: 15 mm).
[0036] The foam metal A is formed of aluminum, which is an air
permeability porous member which is cut after closed cell molding,
and subjected to a compression process. The cracks are caused by
compressing the aluminum with which the closed cells are formed, so
that the closed cells are communicated with each other through the
cracks. And the space 69 shown in FIG. 3 is provided at the back of
the sound absorbing member represented by (a), (b), and (c) in the
graph. A distance of the space 69 is 30 mm for the absorption
member represented by the sign (a), 60 mm for (b), and 90 mm for
(c).
[0037] As shown in FIG. 4, in order to absorb a sound of a
relatively low frequency not more than 1 kHz, the foam metal plate
of the air-permeability porous member is used as a sound absorbing
member and a space is provided at the back of the foam metal plate,
thereby sound absorption degree is remarkably increases compared
with that of the conventional sound absorbing member.
[0038] FIG. 5 is a schematic block diagram of the reflected sound
reduction structure. A collision sound repeats the expansion
attenuation and the interference attenuation due to the diffuse
reflection in the process of passing through the foam metal plate
55 to reach the opposite side of the foam metal plate 55. On the
opposite side of the foam metal plate 55, the developing device 3
(See FIG. 1.) is arranged as internal part necessary for the image
forming process. Between the foam metal plate 55 and the reflection
wall 3a of the developing device 3 disposed in a location opposed
to the foam metal plate 55, a space having a width W (e.g. 20 mm)
is provided. Traveling waves having passed through the foam metal
plate 55 are reflected by the reflection wall 3a and propagated to
and from in the space 69 of 20 mm. In this process, the traveling
waves and reflected waves perform interference attenuation. The
attenuated reflected sound again passes through the foam metal
plate 55. Therefore, about 80.degree. of the actuation sound
(incident sound) emitted from the sound source is absorbed when the
sound returns to the sound source side.
[0039] In this embodiment, the foam metal plate 55 is arranged in a
part of the manual sheet feed cover 54, which is an exterior wall
of the manual sheet feed unit 5. The foam metal plate 55 is
easy-machinable in machining such as bending and boring. For this
reason, the manual sheet feed cover 54 may be entirely formed with
foam metal.
[0040] Further, the example of using foam metal for the exterior
wall is not limited to the manual sheet feed unit, but foam metal
can be applied to a portion, where the actuation portion which
emits an actuation sound of a relatively low frequency is disposed
in an open space, for example, of an exterior cover near the
movable tray in a sheet discharging portion to which a sheet is
discharged.
[0041] Furthermore, in this embodiment, a surface corresponding to
the reflection wall is the reflection wall 3a of the developing
device 3. The reflection wall, however, may be a surface of another
internal part in the image forming apparatus. And in the case that
there is a space between the exterior wall of the housing and the
internal part and there is a noise source having an open space
outside the exterior wall of the apparatus, the similar effect is
obtained.
[0042] In addition, as shown in FIG. 7, the present invention is
also applicable for attenuating an actuation sound generated by a
pair of sheet conveying rollers 41 as an actuation portion inside
the housing 21 opposed to the sheet discharging port 27 as an
opening portion formed in the exterior wall 22 of the housing
21.
[0043] That is, between a pair of sheet conveying rollers 41 and a
reflection wall 7a of the fixing device 7 as an internal part, a
foam metal plate 71 as a sound absorbing member is disposed away
from the reflection wall 7a to form a space 72 between the foam
metal plate 71 and the reflection wall 7a. With this reflected
sound reduction structure 28, the actuation sound of the pair of
sheet conveying rollers 41 is attenuated by the foam metal plate 71
and the space 72 and cannot be amplified by the reflection due to
the reflection wall 7a.
[0044] Next, a preferable example of applicable scope of each
feature in the present invention will be described hereinafter.
[0045] 1. Regarding Porosity of Foam Metal
[0046] With regard to the sound absorption performance of the foam
mental, a high porosity is generally preferable. And a material of
the sound absorbing member of the foam metal produced by the
typical manufacturing method is mainly aluminum (A cast metal may
be used.). When the material of the foam metal is aluminum and the
porosity is about 50%, an aluminum specific gravity becomes 2.74
gf/cc, and an apparent specific gravity is 1.37 gf/cc, which is
substantially equivalent to a gravity of 1.3 gf/cc. of ABS used as
general resin material for an exterior coating.
[0047] That means, porosity of not less than 50% is preferable to
the conventional performance, not only from a viewpoint of the
sound absorption performance but also from an ergonomic viewpoint
such as an operability of opening and closing of the manual sheet
feed unit, and a physical distribution or an installation cost
because of reduction in weight of the body of the apparatus. The
present embodiment uses a foam metal of aluminum having porosity
not less than 50.degree. and not more than 95.degree..
[0048] 2. Regarding Width (thickness) of Space
[0049] When the width of the space 69, 72 behind the foam metal
plate 55, 71 increases, a degree of sound absorption at a low
frequency bandwidth is improved. However, a clearance between the
foam metal plate and an internal part (the inner parts in the body
of an apparatus) cannot be set without limit. FIG. 8 is a graph
showing a relation between a space behind the foam metal plate and
a degree of sound absorption. In FIG. 8, sound absorbing members
represented by reference signs (f), (g), (h), and (j) are foam
metal plates B having a plate thickness of 10 mm. Incidentally, the
foam metal plate B has the same thickness of 10 mm as the foam
metal plate A, but an expansion ratio of the foam metal plate B is
higher than that of the foam metal plate A.
[0050] Material of the foam metal plate B is aluminum. The foam
metal plate B is air-permeability porous member which is cut after
closed cell forming, and through-holes are formed. The closed cells
are communicated with each other by forming the through-holes in
the aluminum with which the closed cells are formed. With regard to
a width of the space behind the foam metal plate B, a graph shown
by the sign (f) is 0 mm, a graph shown by the sign (g) is 20 mm, a
graph shown by the sign (h) is 40 mm, and a graph shown by the sign
(j) is 60 mm.
[0051] In FIG. 8, for the foam metal plate of graph (f) with no
space, degree of sound absorption is 0.8 at a frequency of 2.5 kHz,
and the degree of sound absorption not less than 0.8 cannot be
achieved within a range of frequencies not more than 1 kHz.
However, for the foam metal plate having the space width of 20 mm
shown by the sign (g), degree of sound absorption is 0.8 at a
frequency of 1 kHz. Therefore, the actuation sound can be
attenuated, if the space width is set to not less than 20 mm. And
in the image forming apparatus of the present embodiment, it is
realistically possible that an internal part is installed to allow
an opening to be spaced about 20 mm away from the interior surface
of the exterior wall 22. And effective reflected sound reduction
structure can be arranged in the conventional space.
[0052] In the applicable places which have affordable space inside
the body, it is theoretically preferable that a thickness of space
69, 72 is set to (1/4) .lamda. where a wavelength at which a sound
of a center frequency of noise is propagated in the air is .lamda.,
because the maximum interference cancel effect is achieved.
[0053] 3. Plate Thickness of Foam Metal
[0054] A plate thickness of the foam metal is not specifically
limited for convenience of a method of forming a foam metal plate
55, 71 and from a viewpoint of sound absorption performance. FIG. 9
is graphs showing the sound absorption performances of foam metal
plates different from the sound absorbing member mentioned above in
the embodiment. In FIG. 9, sound absorbing members of graphs
represented by the signs (k) and (m) are a foam metal C having a
plate thickness of 2.5 mm. A width of the space behind the foam
metal C is 50 mm for the graph of the sign (k) and 100 mm for the
graph of the sign (m). Although the plate thickness of the foam
metal plate in FIGS. 4 and 8 used in the explanation of the
embodiment is 10 mm, it is apparent for FIG. 9 that a sound
absorption degree not less than 0.8 can be accomplished at a
frequency of 1 kHz or less depending on the behind space, even with
the plate thickness of 2.5 mm. And generally a plate thickness of
resin material used for exterior walls of the image forming
apparatus is ranging from about 2.5 mm to about 3 mm, and it is
possible to replace with the conventional exterior walls in a
viewpoint of the plate thickness.
[0055] That is, plate thickness of the optimal sound absorption
effect may be selected within the scope where there is no change in
a position of an exterior wall and there is no intrusion into an
internal part space in the housing.
[0056] With the above mentioned configuration, the foam metal plate
as a sound absorbing member is excellent in heat resistance to
maintain for example a sound absorption degree of not less than 0.8
at a center frequency of 500 Hz, thereby products can obtain the
standard of flame retardancy. (A flame retardancy for a sheet
material as an exterior is not less than the standard HF-2 and not
more than 25 cm.sup.2).
[0057] The conventional sound absorbing member made of inorganic
fiber such as glass wool cannot be self-support as a single unit
because of its low mechanical strength, therefore it is difficult
to install on the exterior wall without forming a complex structure
together with a perforated metal plate or a resin plate. While, the
sound absorbing member of the foam metal plate of the present
invention has a high mechanical strength and it is easy to
install.
[0058] The conventional sound absorbing member such as polyurethane
foam and glass wool has troubles of easy breakage damage and
breakage into dust due to vibration, and occasional time
degradation. Further, the performance of sound absorption may
become low when absorbing water in the atmosphere. While, the sound
absorbing member of the foam metal plate of the present invention
has less possibility of breakage damage and time degradation.
Further, the sound absorption performance is hardly reduced even
though it absorbs water in the atmosphere, and it can maintain the
sound absorption performance for a long time.
[0059] The conventional sound absorbing member can not be coated
with coating, thereby it is not suitable for an exterior member
while the sound absorbing member of foam metal plate of the present
invention can be coated with coating and can be used as an exterior
member.
[0060] If the conventional sound absorbing member is made
self-supported by forming a space between it and the reflection
wall, it is required to support the conventional sound absorbing
member by fastening through a spacer to the exterior wall or to
support the exterior wall and the sound absorbing member by a duct
structure. Therefore, it is impractical in terms of cost, space,
and exterior appearance. On the contrary, since the sound absorbing
member of the foam metal plate of the present invention is superior
in strength to the conventional sound absorbing member,
installation structure becomes simple. Therefore, the image forming
apparatus of the present invention can be made the practical
structure in terms of cost, space, and exterior appearance.
[0061] The reflected sound reduction structure for the actuation
portion (sound source), which cannot be sealed, emitting the
actuation sound in the image forming apparatus of the present
invention is provided with the sound absorbing member formed of a
foam metal plate in the opening portion formed in the exterior wall
as a reflection wall. Therefore, a space for attaching the sound
absorbing member between the sound source and the exterior wall is
dispensable. As a result, the image forming apparatus can be
prevented from made into larger in size.
[0062] As the image forming apparatus according to the invention is
provided with a space on the backside of the sound absorbing member
to increase the degree of sound absorption, the space between the
exterior wall and the internal part in the apparatus can be
effectively used so as to avoid an increase in size of the image
forming apparatus.
[0063] In the image forming apparatus of the present invention, the
foam metal plate can dramatically reduce the low frequency noise,
which is a sound of mainly not more than 1 kHz emitted from a sound
source, which cannot be sealed in the vicinity of the exterior, and
which noise is difficult to reduce by the conventional method of
attaching the sound absorbing member on the exterior wall.
[0064] If the present invention is applied to the image forming
apparatus, as shown in FIG. 7, in which the actuation portion
opposed to the opening portion formed in the exterior wall of the
housing is provided inside the housing, the apparatus can improve
the attenuation effect. Further it can efficiently utilize the
space between the actuation portion and the reflection wall of the
internal part, thereby avoiding an increase in size of the
apparatus.
[0065] Further, in the image forming apparatus as shown in FIG. 7,
not only the foam metal but also the space between the internal
part and the foam metal contributes the actuation sound reduction,
thereby increasing the actuation sound attenuation effect to
decrease the actuation sound of the actuation portion, which is
leaked from the opening portion. In addition, even if the actuation
sound is not more than 1 kHz, the actuation sound can be surely
attenuated.
[0066] 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.
[0067] This application claims the benefit of Japanese Patent
Application No. 2005-349847, filed Dec. 2, 2005, which is hereby
incorporated by reference herein in its entirety.
* * * * *