JP2010217664A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus for suppressing leaking out of the image forming apparatus of noise emitted through a gap between a mounting opening of an inside covering member and an attachment/detachment component. <P>SOLUTION: This image forming apparatus includes the attachment/detachment component attachably/detachably mounted to the inside of a case, the inside covering member having the mounting opening, an outside covering member, and a sound insulating member that is arranged between the inside covering member and outside covering member and is opened or closed so as to form a state where at least mounting opening of the inside covering member is exposed and a state where it is covered to insulate sound. A plurality of through-holes 6 are formed in a certain arrangement pattern in at least a part facing the mounting opening of the inside covering member of the sound insulating member 16. When the sound insulating member and the outside covering member are mutually closed, the part of the sound insulating member having the through-holes and the outside covering member are arranged in a state where they face each other separately to form an air layer 7 between both, and a sound absorbing structure is constituted by the part of the sound insulating member having the through-holes and the air layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  In an image forming apparatus such as a printer, a copying machine, or a facsimile using a recording method such as an electrophotographic method, the operation sound accompanying the image forming operation may be recognized as noise by leaking out of the device.

  Conventionally, an exterior material structure of an image forming apparatus that generates noise is a sealed structure with an exterior member and an interior member facing each other with a gap therebetween, and is generated between the exterior member and the interior member during operation. There is known an exterior material structure in which a resonance space corresponding to a frequency is formed, and a passage connected to at least part of the interior of the image forming apparatus main body is provided in the content member (Patent Document 1).

JP 2000-235396 A

  The present invention has an inner covering member that covers the inside of the housing, an outer covering member that is opened and closed so that the inner covering member is exposed and covered, and a mounting formed on the inner covering member. As an image forming apparatus having a detachable component that is detachably mounted through the mouth, noise emitted through a gap between the mounting port of the inner covering member and the detachable component leaks to the outside of the image forming apparatus. It is an object of the present invention to provide an image forming apparatus that can be reduced.

An image forming apparatus according to the present invention (A1) includes a detachable component that is detachably mounted inside a housing,
An inner covering member that is attached to the housing in a state of covering the inside thereof and has a mounting opening that is passed through when the detachable component is attached and detached;
An outer covering member that is opened and closed so that the inner covering member is exposed and covered; and
A sound insulating member that is disposed between the inner covering member and the outer covering member, and that is opened and closed so that at least a mounting opening of the inner covering member is exposed and covered and sound-insulated.
When a plurality of through holes are formed in a fixed arrangement pattern in a portion of the sound insulating member facing the mounting opening of the inner covering member, while the sound insulating member and the outer covering member are closed with each other The sound insulating member in which the through hole is formed by arranging the sound insulating member in which the through hole is formed and the outer covering member so as to face each other with a space therebetween to form an air layer therebetween. And the air layer constitute a sound absorbing structure.

In the image forming apparatus of the invention (A2), in the image forming apparatus of the invention A1, when the sound absorption frequency f ₀ in the sound absorbing structure is expressed by the following equation:
f ₀ = C / 2π · √ [12P / {h (12t + 3πd) + 4Ph ³ }]
[C: speed of sound (mm / sec), P: aperture ratio of sound insulation member, h: thickness of air layer (mm), t: thickness of sound insulation member (mm), d: interval between through holes (mm)]
Regarding the sound insulation member, the through hole, and the outer cover member, the sound absorption frequency f ₀ in the sound absorption structure is a target of sound absorption among noises emitted through the gap between the mounting opening of the inner cover member and the detachable component. It is set so as to satisfy a condition that matches the sound frequency f _n .

The image forming apparatus according to the invention (A3) is the image forming apparatus according to the invention A2, wherein the detachable part is a replacement part equipped with at least a photoreceptor and a charging device, and the noise frequency f _n is the charging device. This is the frequency of noise generated during charging.

  The image forming apparatus according to the invention (A4) is the image forming apparatus according to any one of the inventions A1 to A3, wherein the air layer is formed as an unsealed space.

  According to the image forming apparatus of the invention A1, the inner covering member that covers the inside of the casing, the outer covering member that is opened and closed to open and close the inner covering member, and the inner covering member are covered with the inner covering member. In spite of an image forming apparatus having a detachable component that is detachably mounted through a mounting port formed in the cover member, noise emitted through a gap between the mounting port of the inner cover member and the detachable component is generated. Leakage to the outside of the image forming apparatus can be reduced.

  In the image forming apparatus according to the invention A2, the effect of the invention A1 can be obtained more accurately than when the configuration of the invention is not provided.

  In the image forming apparatus according to the invention A3, it is possible to reduce the leakage of noise generated when the charging device is charged to the outside of the image forming apparatus, as compared with the case where the configuration of the invention is not provided.

  In the image forming apparatus according to the invention A4, it is possible to suppress an increase in the temperature inside the housing as compared with the case where the configuration of the invention is not provided.

1 is a perspective view showing an outline of an overall appearance of an image forming apparatus according to an embodiment of the present invention (a state in which an exterior cover or the like is closed). FIG. 2 is a perspective view showing a state in which an exterior cover on the installation front side in the image forming apparatus of FIG. 1 is opened. FIG. 2 is a perspective view showing a state where a sound insulation cover in the image forming apparatus of FIG. 1 is opened. FIG. 2 is an explanatory diagram illustrating a main configuration inside a housing in the image forming apparatus of FIG. 1. FIG. 2 is a partial cross-sectional view illustrating a configuration of an image forming unit in the image forming apparatus of FIG. 1. It is a schematic sectional drawing which expands and shows the structure (sound absorption structure) of the sound insulation cover and exterior cover in the mounting opening of the interior cover of FIG. It is explanatory drawing which shows the arrangement pattern of the several through-hole formed in a sound-insulation cover. FIG. 3 is an explanatory diagram showing the contents of symbols in Formula 1. It is explanatory drawing which shows the content of the symbol etc. in Formula 1 and Formula 2. FIG. It is a graph which shows the relationship between the hole interval of a through-hole represented using Formula 1, and a frequency.

  Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as “embodiments”) will be described with reference to the accompanying drawings.

  FIG. 1 shows a perspective view of the entire appearance of the image forming apparatus 1 according to this embodiment, FIG. 2 shows a state in which an exterior cover on the installation front side of the image forming apparatus is opened, and FIG. FIG. 4 shows a main configuration inside the casing of the image forming apparatus.

  As shown in FIG. 1 and the like, the image forming apparatus 1 includes an image forming unit 2 in which an image forming device and the like are installed, and a paper feeding unit 4 that receives and feeds recording paper 9 supplied to the image forming unit 2. Have.

  The image forming unit 2 includes a housing 10 formed in a box shape using a material such as a support frame and a sheet metal, and installation devices such as an image forming device 20 and a fixing device 35 installed in an internal space of the housing 10. And cover members such as an interior cover 12, an exterior cover 14, and a sound insulation cover 16 that are attached in a state of covering the periphery of the housing 10. A curved surface portion 19 formed of a partially inclined surface formed on the upper portion of the housing 10 is a paper discharge portion that discharges and stores the recording paper 9 on which an image is formed.

  As shown in FIG. 4, the image forming apparatus 20 employs an intermediate transfer method, and specifically, different colors (in this example, yellow: Y, magenta: M, cyan: C, black: K). A plurality of (four in this example) image forming units 20 (20Y, 20M, 20C, 20K) that form toner images of a total of four colors) are made to face the outer peripheral surface of the intermediate transfer belt 30 in the intermediate transfer system. In this state, it is configured to be arranged in series at intervals in the rotational movement direction.

  Each of the image forming units 20Y, 20M, 20C, and 20K in the image forming device 20 is a drum-shaped photoconductor 21 that is arranged to rotate, a charging device 22 that is arranged around the photoconductor 21, and an exposure. The apparatus 23, the developing device 24, the primary transfer device 25, the cleaning device 26, and the like.

  Among these, the photosensitive member 21 is formed with a photosensitive layer (photoconductive layer) made of an organic photosensitive material or the like on a cylindrical peripheral surface of a conductive cylindrical base material that is rotatably supported and grounded. Is. The photosensitive member 21 is rotationally driven at a required speed in a required direction (direction indicated by an arrow) by power of a rotary drive device (not shown). The charging device 22 includes a charging roll 22a that rotates in contact with at least an image forming effective area in the rotation axis direction of the photosensitive member 21, and the charging roll 22a has only a direct current or a direct current superimposed on a direct current from a power supply unit (not shown). The applied charging voltage is applied.

  The exposure device 23 irradiates the photoconductor 21 with light according to image information input to the image forming apparatus 1 to form an electrostatic latent image. As the exposure device 23, for example, a scanning exposure device configured using optical components such as a semiconductor laser and a polygon mirror, or a non-scanning exposure device configured using light emitting diodes and optical components is used. . The exposure device 23 is configured to receive an image signal after image information input to the image forming apparatus 1 has been subjected to required processing by an image processing device (not shown).

  The developing device 24 develops the electrostatic latent image by supplying a developer (toner) suitable for the developing method to the developing area of the photoreceptor 21. As the developing device 24, for example, a two-component developing device that performs reversal development using a two-component developer containing (nonmagnetic) toner and (magnetic) carrier is used.

  The primary transfer device 25 is provided with a primary transfer roll 25a that rotates in contact with at least a charged region in the rotation axis direction of the photoconductor 21, and the opposite to the charging polarity of the toner from a power supply unit (not shown) on the transfer roll 25a. The primary transfer voltage for the side polarity is applied. The cleaning device 26 is provided with a cleaning member such as an elastic plate that comes into contact with the peripheral surface of the photosensitive member 21 after transfer, and a collection container that collects deposits such as toner removed by the cleaning member.

  The intermediate transfer belt 30 is wound around a plurality of support rolls 31a, 31b, 31c and the like, and is rotatably supported under a predetermined tension. The photosensitive member 21 and the transfer device 25 (in each image forming unit 20 of the image forming device 20). The transfer rolls 25a) are arranged so as to move sequentially passing through the primary transfer position. The intermediate transfer belt 30 is rotated at a required speed in a required direction (direction indicated by an arrow) by a driving roll 31 that is rotationally driven by a driving device (not shown).

  As the intermediate transfer belt 30, a belt formed into an endless shape using a material such as a resin or rubber that contains a conductive agent and is adjusted to a required volume resistivity is used. On the outer peripheral surface side of the portion of the intermediate transfer belt 30 supported by the secondary transfer support roll 31b, a secondary transfer roll 32 that rotates in contact with the outer peripheral surface of the belt with a required pressure is installed. A secondary transfer voltage is applied to either the secondary transfer support roll 31b or the secondary transfer roll 32 from a power supply unit (not shown). A cleaning device (not shown) for cleaning the outer peripheral surface of the belt after the secondary transfer is installed on the outer peripheral surface side of the portion of the intermediate transfer belt 30 supported by the driving support roll 31a.

  The fixing device 35 is driven in a roll form, a belt form, or the like that is driven to rotate in the direction indicated by the arrow with respect to the inside of the heat-insulating housing 36 and whose surface temperature is heated to a required temperature by a heating means. The rotating body 37 and a pressurizing rotating body 38 such as a roll form and a belt form that are driven to rotate by being brought into contact with a required pressure so as to substantially follow the axial direction of the heating rotating body 37 are installed.

  In the housing 10 of the image forming unit 2, the recording paper 9 supplied from the paper supply unit 4 is transported to the secondary transfer position, and is configured by a plurality of paper transport roll pairs 39a, 39b and the like and a transport guide material. A paper feed path is provided. In addition, a discharge path composed of a pair of sheet transport rollers 39e and the like and a transport guide material for transporting the recording paper 9 discharged from the fixing device 35 toward the discharge port to the paper discharge unit 19 is provided. ing.

  The paper feed unit 4 is a box (not shown) formed using a material such as a support frame or a sheet metal, a paper container 41 installed in an internal space of the casing, and a paper container 41. The recording paper 9 is sent out one by one, and is composed of a delivery device 42, an exterior cover 40 that covers the inside of the housing, and the like. The paper container 41 is detachably attached to the housing, and has a holding plate 43 that holds the recording paper 9 to be stored having a desired size and type in a stacked state.

  Image formation by the image forming apparatus 1 is performed as follows. Here, it is assumed that a full-color print for forming a full-color image composed of four color toner images of Y, M, C, and K is requested, and the operation content at that time will be described.

  When full-color printing is requested, as shown in FIG. 4, in each image forming unit 20 (Y, M, C, K) of the image forming unit 2, the photosensitive drum 21 that starts rotating is charged to a predetermined potential by the charging device 22. The photosensitive drum 21 after charging is exposed based on the image signal from the exposure device 23 to form an electrostatic latent image according to each color component, and then the electrostatic latent image is developed in the developing device 24. Each color (Y, M, C, K) toner image is formed by developing with the corresponding color toner. The toner images formed by the image forming units 20 are electrostatically transferred so that the photosensitive drum 21 is successively superimposed on the intermediate transfer belt 30 at the primary transfer position facing the primary transfer device 25, and thereafter, The intermediate transfer belt 30 is conveyed to a secondary transfer position facing the secondary transfer roll 35.

  Subsequently, when the recording paper 9 conveyed from the paper supply unit 4 at a required timing is sent to the secondary transfer position of the image forming unit 2, the toner images on the intermediate transfer belt 30 are collectively put on one side of the recording paper 9. Electrostatic transfer. The recording paper 9 onto which the toner image has been transferred is introduced into the fixing device 35 of the image forming unit 2. In the fixing device 35, the paper 9 on which the toner image has been transferred is heated and pressurized when passing through the contact portion between the heating rotator 37 and the pressure rotator 38, thereby melting the toner image and the paper 9. To settle. After the fixing is completed, the recording paper 9 is discharged from the fixing device 35 and then conveyed to a discharge unit 19 formed on the top of the housing 10.

  As described above, a full color image is formed on one side of one sheet of recording paper 9. When a plurality of full-color images are required to be formed, the above operation is repeated in the same manner. Further, in the image forming apparatus 1, by operating only the black color image forming unit 20K among the plurality of image forming units 20, it is also possible to form a black and white image composed of a K color toner image.

  Further, in the image forming apparatus 1, as shown in FIG. 5, the photosensitive member 21 and the charging device 22 (charging roll 22a) in the four image forming units 20 of the image forming device 20 are integrally mounted on the support frame. It is formed as an exchange unit 29 and is configured to be detachably attached to the inside (mounting space portion 11) of the housing 10 of the image forming unit 2.

  As shown in FIGS. 2 and 5, the housing 10 of the image forming unit 2 is formed of a plurality of materials 10 a to 10 d such as a support frame and a sheet metal, and the internal space is external (mainly the installation front surface). A plate-shaped interior cover 12 is attached around the front side of the housing 10 so as to be covered and hidden from the outside. Further, as shown in FIG. 2 and the like, each image forming unit 20 is located at a position corresponding to the opening of each mounting space portion 11 of each image forming unit 20 (Y, M, C, K) of the interior cover 12. A mounting opening 13 (Y, M, C, K) is formed through which the replacement unit 29 is attached and detached.

  As shown in FIG. 2 to FIG. 3, FIG. 5, etc., the housing 10 of the image forming unit 2 is in a state where the interior cover 12 in which the mounting opening 13 is formed is exposed to the outside and is covered from the outside. A plate-like exterior cover 14 that is opened and closed is attached. The exterior cover 14 is attached to a predetermined part of the housing 10 in a state of opening / closing (swinging) via a hinge (hinge part) 15a.

  Reference numeral 15b in FIGS. 2, 3 and the like is a holding arm for fixing and holding the state when the outer cover 14 is opened at a required position, and reference numerals 15c and 15d hold the state when the outer cover 14 is closed. Magnet-type fixing auxiliary means (such as a combination of a magnet body and a magnetic plate) and dotted arrows B and C indicate the opening direction (B) and the closing direction (C) of the outer cover 14. Further, reference numeral 14B in FIG. 5 is an upper surface exterior cover that is attached in a state of closing the internal space that can be seen from the upper surface side of the housing 10, and 14C is an interior that can be seen from the rear surface side of the housing 10 (the back surface opposite to the installation front surface). It is the back exterior cover attached in the state which plugs up space.

  Further, as shown in FIGS. 2 to 3 and the like, the interior cover 12 covers the four mounting openings 13 (Y, M, C, K) and the surroundings thereof from the outside and covers them from the outside. A plate-like sound insulation cover 16 that is opened and closed to make a sound insulation state is attached.

  As shown in FIG. 3 and the like, the sound insulation cover 16 is tightly sealed with a peripheral portion of each mounting opening 13 of the interior cover 12 against a flat board 16a having a size that covers the four mounting openings 13 at a time. As described above, the outer frame (edge plate) 16b is formed so as to surround the end portion of the substrate 16a, and the partition plates 16c and 16d are formed so as to partition the region surrounding each mounting opening 13 individually. It has a structure. The sound insulation cover 16 is attached to a portion below the mounting opening 13 of the interior cover 12 in a state of opening / closing (swinging) in the directions indicated by dotted arrows B and C via a hinge (hinge part) 17a. . Further, between the sound insulation cover 16 and the interior cover 12, there is provided a fixing auxiliary means (not shown) for maintaining the state when the sound insulation cover 16 is closed.

  Here, the replacement work of the replacement unit 29 will be described.

  First, in the image forming apparatus 1, after the front exterior cover 14 is opened (FIG. 2), the sound insulation cover 16 is opened (FIG. 3). In this state, the replacement unit 29 exposed to the four mounting openings 13 formed in the interior cover 12 is removed by being pulled out of the mounting space so as to pass through the mounting openings 13. On the other hand, a new replacement unit 29 is mounted by being pushed into the mounting space portion 11 through the four mounting ports 13. After the mounting, the sound insulation cover 16 is closed to cover the four mounting openings 13 to make sound insulation, and finally the exterior cover 14 is closed. As a result, the image forming apparatus 1 is in a state in which the exterior cover 14 (including the sound insulation cover 16) is closed, as shown in FIG.

  As shown in FIGS. 2 to 3 and FIGS. 5 to 6, the sound insulating cover 16 has at least portions facing the mounting ports 13 of the interior cover 12 (each mounting port of the flat substrate 16 a). A plurality of through-holes 6 are formed in the portion 13 and the portion surrounding it.

  The plurality of through holes 6 are formed in a fixed arrangement pattern. In this embodiment, as shown in FIG. 7, the distances d between the center points 61 of the adjacent through holes 6 are all the same value. It is formed with the pattern which becomes. Each of the plurality of triangles indicated by the alternate long and short dash line in FIG. 7 is a regular triangle whose one side is the dimension d. In this embodiment, a circular hole shape is formed as the through hole 6, but it may be another hole shape hole that can determine the center point, for example, a regular polygon. .

  Further, when the sound insulation cover 16 is closed together with the exterior cover 14 (see FIG. 6 and the like), the portion of the substrate 16a in which the through hole 6 is formed and the exterior cover 14 have a predetermined interval h. The air layer 7 is formed between the sound insulating cover 16 and the outer cover 14 (the inner surface thereof). In the image forming apparatus 1, a sound absorbing structure is formed by the air layer 7 and the portion of the substrate 16 a of the sound insulating cover 16 in which the plurality of through holes 6 are formed.

  The air layer 7 is formed by arranging an outer surface portion of the substrate 16a of the sound insulating cover 16 in which a plurality of through holes 6 are formed and a planar inner surface side of the exterior cover 14 with a predetermined interval. . In addition, the air layer 7 is a non-sealed space that is formed only by the gaps of the above intervals without forming a partition space by arranging a partition member between the substrate 16a of the sound insulating cover 16 and the inner side surface of the exterior cover 14. It formed (refer FIG. 5, FIG. 6).

  Further, the sound insulation cover 16, the through hole 6 and the outer cover 14 constituting the sound absorbing structure are set as follows.

That is, when the sound absorption frequency f ₀ in the sound absorption structure is represented by the following formula (1):
f ₀ = C / 2π · √ [12P / {h (12t + 3πd) + 4Ph ³ }] (1)
For the sound insulation cover 16, the through hole 6, and the exterior cover 14, the sound absorption frequency f ₀ of the noise emitted through the gap S (see FIG. 6) between the mounting opening 13 of the interior cover 12 and the replacement unit 29 is absorbed. Is set so as to satisfy a condition that matches the frequency f _n of the target sound. For each symbol in equation (1), as shown in FIG. 8, P is the aperture ratio of the sound insulation cover 16 (substrate 16a), h is the thickness of the air layer (in other words, the outer surface of the sound insulation cover 16 and the exterior cover). 014 (interval with the inner surface of 014) (mm), t indicates the thickness (mm) of the sound insulation cover 16 (substrate 16a), and d indicates the interval (mm) between the through holes. Symbol C indicates the speed of sound (mm / sec). This formula 1 refers to and refers to the matters described on pages 80 to 81 of Acoustical Acoustics Course 3 Architectural Acoustics by the Acoustical Society of Japan (House Nagata, published by Corona, 1988).

That is, the opening ratio P, the air layer thickness h, the thickness t of the sound insulation cover 16, and the distance d between the through holes 6 with respect to the sound insulation cover 16, the through hole 6 and the exterior cover 14 so that f ₀ = f _n. Adjust the settings for etc.

Here, the aperture ratio P of the sound insulation cover 16 (substrate 16a) varies depending on the shape of the through holes 6 and the arrangement pattern thereof. Therefore, in this embodiment, as shown in FIGS. 7 and 9, the shape of the through holes 6 is a circle having a radius r, and the arrangement pattern thereof is a dense arrangement (for example, the center points of adjacent through holes 6). In the case where 61 is an arrangement in the state of being located at the apex of an equilateral triangle composed of one side d as a unit reference of the arrangement pattern, the aperture ratio P is a value obtained by the following equation (2). That is, the aperture ratio P in this case is obtained by obtaining the ratio (area occupancy ratio) occupied by the through-hole 6 (part 6 ′) existing in the equilateral triangle E as shown in an enlarged view in FIG. It is done.
^{P = [3 · (πr 2} /6)] / [(1/2) · √ (3/2) d · d]
= (2π / √3) · (r ² / d ² ) (2)

Further, in this image forming apparatus 1, as noise emitted through the gap S (see FIG. 6) between the mounting opening 13 of the interior cover 12 and the replacement unit 29, charging is performed when the charging device 22 is charged in the replacement unit 29. There is high-frequency noise that occurs with the discharge phenomenon that occurs between the roll 22a and the photoreceptor 21. For this reason, the noise generated during charging of the charging device 22 is set as the noise to be absorbed, and the frequency f _n of the sound to be absorbed is set as the frequency of the noise generated during charging. This frequency f _n is generally twice the frequency of the AC voltage applied to the charging device 22.

In this embodiment, the sound absorbing structure absorbs charging noise having a frequency f _n of “2.7 kHz”, so that the sound insulating cover 16 (substrate 16a) having a thickness t of “2 mm” is closed. The outer cover 14 is arranged so that a space h of “4 mm” is ensured with respect to the planar inner surface of the outer cover 14, and the sound insulating cover 16 is formed of a circular hole having a radius r of “1.5 mm”. On the premise that the through holes 6 are formed in the dense arrangement, the interval d between the through holes 6 is set. FIG. 10 expands the formula 2 into the formula for substituting the formula 1 into the formula 1 to obtain the hole interval d, and the formula (frequency) substituting the values of t, h, r and the value of the sound velocity C (340,000 mm / sec). For f ₀ ), the horizontal axis represents the hole interval d, and the vertical axis represents the frequency. In addition, the interior cover 14, the exterior cover 14, and the sound insulation cover 16 were made of plastic molded products obtained using ABS resin.

As a result, in this embodiment, in order to absorb the charging noise of “2.7 kHz (= f _n )”, the through hole 6 satisfies the condition that the hole interval d is about “7.53 mm”. It was decided to form. Incidentally, in this case, the opening area of one mounting opening 13 is 3,596Mm ^2, the area of the substrate 16a of the sound insulation cover 16 is 22,875Mm ^2, a through hole 6 for the substrate 16a Total 306 Individually formed.

  In the image forming apparatus 1, when the sound insulation cover 16 is closed together with the exterior cover 14 and a printing operation is performed, the charging device of each replacement unit 29 in the four image forming units 20 (Y, M, C, K). Charging noise with a frequency of 2.7 kHz from 22 (charging roll 22 a) hardly leaks out of the image forming apparatus 1.

  Further, in this image forming apparatus 1, the sound insulation cover 16 has a plurality of through holes 6 and the air layer 7 formed between the sound insulation cover 16 and the exterior cover 14 is formed as an unsealed space as described above. Therefore, the heat generated from the installation equipment such as the exposure apparatus 23 inside the housing 10 leaks from the gap S between the replacement unit 29 and the mounting space 11 (including the mounting port 13), and then is sound-insulated. By passing through the through-hole 6 of the cover 16 and leaking into the air layer 7, it is discharged (exhausted). Thereby, it is suppressed that the temperature inside the housing | casing 10 rises.

[Other embodiments]
In the above-described embodiment, the sound insulation cover 16 is attached to the interior cover 14 so as to be openable and closable. However, the sound insulation cover 16 is attached in a state of being fixed to the inner surface side of the exterior cover 14, and the exterior cover 16 is opened and closed. In addition, the sound insulation cover 16 can be configured to be opened and closed. In this case, the sound insulating cover 16 is attached to the inner surface side of the outer cover 14 in a state of facing the gap d as necessary to form the air layer 7. It is configured to be a sealed space.

  In the above-described embodiment, the image forming apparatus 1 adopting the intermediate transfer method is exemplified as the image forming apparatus 20, but the image forming apparatus 20 is a photosensitive in each image forming unit 20 (Y, M, C, K). The toner image formed on the body 21 may be directly transferred onto the recording paper 9 conveyed by a paper conveying belt or the like. Further, the image forming apparatus 20 in the image forming apparatus 1 may be configured by one image forming unit that does not employ the intermediate transfer method, or may be configured by a plurality of image forming units other than four. It may be.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 6 ... Through-hole 7 ... Air layer 10 ... Housing | casing 12 ... Interior cover (inner cover member)
13 ... Installation port 14 ... Exterior cover (outer covering member)
15. Sound insulation cover (sound insulation member)
21 ... Photoconductor 22 ... Charging device 29 ... Replacement unit (detachable part, replacement part)
S: Gap (gap between the opening of the inner covering member and the removable part)

Claims (4)

A detachable part that is detachably mounted inside the housing;
An inner covering member that is attached to the housing in a state of covering the inside thereof and has a mounting opening that is passed through when the detachable component is attached and detached;
An outer covering member that is opened and closed so that the inner covering member is exposed and covered; and
A sound insulating member that is disposed between the inner covering member and the outer covering member, and that is opened and closed so that at least a mounting opening of the inner covering member is exposed and covered and sound-insulated.
When a plurality of through holes are formed in a fixed arrangement pattern in a portion of the sound insulating member facing the mounting opening of the inner covering member, while the sound insulating member and the outer covering member are closed with each other The sound insulating member in which the through hole is formed by arranging the sound insulating member in which the through hole is formed and the outer covering member so as to face each other with a space therebetween to form an air layer therebetween. And an air layer. When the sound absorption frequency f ₀ in the sound absorption structure is expressed by the following equation:
f ₀ = C / 2π · √ [12P / {h (12t + 3πd) + 4Ph ³ }]
[C: speed of sound (mm / sec), P: aperture ratio of sound insulation member, h: thickness of air layer (mm), t: thickness of sound insulation member (mm), d: interval between through holes (mm)]
Regarding the sound insulation member, the through hole, and the outer cover member, the sound absorption frequency f ₀ in the sound absorption structure is a target of sound absorption among noises emitted through the gap between the mounting opening of the inner cover member and the detachable component. The image forming apparatus according to claim 1, wherein the image forming apparatus is set so as to satisfy a condition that coincides with a sound frequency f _n . The image forming apparatus according to claim 2, wherein the detachable part is a replacement part equipped with at least a photoreceptor and a charging device, and the noise frequency f _n is a frequency of noise generated when the charging device is charged.   The image forming apparatus according to claim 1, wherein the air layer is formed as a non-sealed space.

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