JP6674658B2 - Sound absorbing device, electronic device and image forming device - Google Patents

Description

  The present invention relates to a sound absorbing device, an electronic device, and an image forming device.

  2. Description of the Related Art Conventionally, as an image forming apparatus, there has been known an image forming apparatus including a sound absorbing device having a Helmholtz resonator structure to suppress operation noise from leaking outside. Patent Literature 1 describes, as a sound absorbing device to be arranged in such an image forming apparatus, a configuration including a first member having an opening and a second member forming a cavity by combining with the first member. Have been.

In the sound absorbing device having the structure of the Helmholtz resonator, the frequency of the sound to be absorbed changes depending on the volume of the cavity, and therefore, it is required to form the cavity with high precision so that the sound of the desired frequency can be absorbed. .
Such a problem is not limited to a configuration in which the first member has an opening as a combination of the first member and the second member forming the cavity. The first member has one of an opening forming surface formed with an opening or an opening facing surface facing the opening forming surface across the cavity, and the second member is provided between the opening forming surface and the opening facing surface. This is a problem that can occur in a configuration having at least a side wall forming portion that forms a side wall surface extending so as to connect the two.

In order to solve the above-described problems, the present invention provides a sound absorbing device including a cavity, and an opening that communicates the cavity with the outside, wherein the sound absorbing device sandwiches the opening forming surface on which the opening is formed or the cavity. A first member having one of the opening opposing surfaces facing the opening forming surface, and at least a side wall forming portion forming a side wall surface extending so as to connect between the opening forming surface and the opening opposing surface. And the second member having, the hollow portion is formed by combining, and the outline shape of the hollow portion defined by the side wall surface viewed from the side of the opening forming surface or the side of the opening facing surface is a polygon. There, among the columnar portion component corresponding to the vertex of the polygons in the side wall forming portions, Rutotomoni provided positioning portion for positioning said first member to a portion of the columnar portion, the other columnar portion first Fixing with one member Cormorants which fixed portion, the thickness of the plate-like portion corresponding to the polygonal sides of the sidewall forming section is characterized in that thin by the thickness remote of the columnar portion.

  ADVANTAGE OF THE INVENTION According to this invention, the hollow part of a sound absorption apparatus has the outstanding effect that it becomes possible to aim at the improvement of the sound absorption effect of the sound of a desired frequency by forming with high precision.

Explanatory perspective view of the sound absorbing device according to the present embodiment, (a) is an explanatory view of a state where a communication portion forming plate is fixed to a cavity forming member, and (b) is a description of a cavity forming member from which the communication portion forming plate is removed. FIG. FIG. 1 is a schematic configuration diagram of an entire copying machine according to an embodiment. FIG. 2 is a schematic diagram of the sound absorbing device according to the embodiment. FIG. 4 is a perspective explanatory view of a cavity forming member in which the cross section of the cavity has a regular triangle shape. FIG. 4 is a perspective explanatory view of a cavity forming member in which a cross section of a cavity has a regular hexagon and a regular triangle.

  Hereinafter, an embodiment of an electrophotographic copying machine (hereinafter, simply referred to as “copying machine 500”) will be described as an image forming apparatus to which the present invention is applied. In the present embodiment, a monochrome image forming apparatus will be described as an example of the copying machine 500, but the present invention can be similarly applied to a known color image forming apparatus.

First, the configuration of the copying machine 500 will be described.
FIG. 2 is a schematic configuration diagram of the entire copying machine 500 according to the present embodiment. In FIG. 2, a scanner 200 as an image reading unit is mounted on an image forming unit 100 of a copying machine 500, and the image forming unit 100 is placed on a paper feeding unit 300. On the scanner 200, an automatic document feeder 400 that is rotatable about a back side (the back side in the drawing) is attached.

  Inside the image forming unit 100, a drum-shaped photoconductor 10 is provided as a latent image carrier. Around the photoreceptor 10, there are arranged a static elimination lamp, a charging device 11 using a charging roller, a developing device 12, a transfer unit 13, and a cleaning device 14 having a photoreceptor cleaning blade. The developing device 12 visualizes the electrostatic latent image on the photoconductor 10 by attaching toner to the electrostatic latent image using a developing roller as a developer carrier.

The transfer unit 13 includes a transfer belt 17 wrapped around two roller members, a first belt stretching roller 15 and a second belt stretching roller 16. The transfer belt 17 is pressed against the peripheral surface of the photoconductor 10 at a transfer position B where the toner image on the photoconductor 10 is transferred onto the recording paper P as a recording medium.
Foreign matter such as residual toner and paper powder remaining on the transfer belt 17 after the recording paper P is separated is scraped off by the transfer belt cleaning member.
A toner replenishing device 20 for replenishing the developing device 12 with new toner is provided on the left side of the charging device 11 and the cleaning device 14 in the image forming unit 100 in FIG.

In the image forming unit 100, the recording paper P sent from the recording paper cassette 61 of the paper supply unit 300 or the manual tray 67 of the manual paper supply unit 68 is conveyed to the discharge stack unit 39 via the transfer position B. A paper transport device 60 is provided. The recording paper transport device 60 transports the recording paper P along the supply path R1 or the manual supply path R2 and the recording paper transport path R.
A registration roller pair 21 is provided upstream of the transfer position B in the recording paper transport path R in the recording paper transport direction.
On the other hand, a fixing device 22 is provided downstream of the transfer position B in the recording paper transport path R in the recording paper transport path. In the fixing device 22, the recording paper P is sandwiched between a heating roller 30 as a heating member and a pressing roller 32 as a pressing member to perform heating and pressure fixing.

  A discharge branching claw 34 and a discharge roller pair 35 are provided further downstream of the fixing device 22 in the recording paper conveyance direction. At the downstream side of the discharge roller pair 35 in the recording paper conveyance direction, there is provided a discharge stack unit 39 for stacking the recording paper P on which an image has been formed and which has passed through the fixing device 22.

  The image forming unit 100 is provided with a switchback device 42 on the right side in FIG. The switchback device 42 reverses the reversing path R3 branched from the position where the discharge branching claw 34 of the recording paper conveyance path R is disposed, and re-registers the recording paper P passing through the reversing path R3 in the recording paper conveyance path R again. The recording paper P is conveyed along the re-conveying path R4 leading to the position of the roller pair 21. A switchback roller pair 43 is provided on the reversing path R3, and a plurality of recording paper conveying roller pairs 66 are provided on the re-conveying path R4.

A laser writing device 47 is provided on the left side of the developing device 12 in the image forming section 100 in FIG. The laser writing device 47 includes a laser light source, a polygon mirror 48 serving as a rotating polygon mirror for scanning, a polygon motor 49, and a scanning optical system such as an fθ lens.
The scanner 200 includes a light source 53, a plurality of mirrors 54, an imaging optical lens 55, an image sensor 56 such as a CCD image sensor, and the like, and a contact glass 57 is provided on an upper surface thereof.
The automatic document feeder 400 is provided with a document set table, and a document stack table is provided at a document discharge position. The automatic document feeder 400 includes a plurality of document feed rollers, and a document is fed from the document set table to the document stack table via the reading position on the contact glass 57 of the scanner 200 by the document feed rollers.

  A plurality of recording paper cassettes 61 for accommodating recording paper P such as paper or OHP film are provided inside the paper supply unit 300. The plurality of recording paper cassettes 61 are provided with a call roller 62, a supply roller 63, and a separation roller 64, respectively. On the right side of the recording paper cassette 61 in FIG. 2, the above-described supply path R1 leading to the recording paper conveyance path R of the image forming unit 100 is formed. The recording path R1 is also provided with several recording paper transport roller pairs 66 for transporting the recording paper P.

  The image forming unit 100 is provided with a manual paper feed unit 68 on the right side in FIG. The manual paper feed section 68 is provided with a manual tray 67 that can be freely opened and closed. The manual paper supply path R2 that guides the recording paper P set on the manual paper tray 67 to the recording paper conveyance path R is formed. ing. Similarly to the recording paper cassette 61, the manual paper feed unit 68 is also provided with a calling roller 62, a supply roller 63, and a separation roller 64.

Next, the operation of the copying machine 500 will be described.
When making a copy using the copying machine 500, first, the main switch is turned on, and if the original is a sheet original such as a plurality of sheets, the original is set on the original setting table of the automatic original feeder 400. If the document is a book document such as a book, the automatic document feeder 400 is opened, the document is directly set on the contact glass 57 of the scanner 200, and the automatic document feeder 400 is closed and pressed.

Thereafter, when the start switch is pressed, when a document is set on the automatic document feeder 400, the scanner 200 is driven after the sheet document is moved onto the contact glass 57 through the document feed path by the document feed roller. Then, the original content is read and discharged onto the original stack table. On the other hand, when an original is set directly on the contact glass 57, the scanner 200 is immediately driven to read the contents of the original.
When reading the document content, the scanner 200 irradiates light from the light source 53 onto the document surface on the contact glass 57 while moving the light source 53 along the contact glass 57. Then, the reflected light is guided by a plurality of mirrors 54 to an imaging optical lens 55 and is input to an image sensor 56, and the image sensor 56 reads the contents of the original.

  In the copying machine 500, the photoconductor 10 is rotated by the photoconductor drive motor at the same time as reading the contents of the document. Then, first, the surface of the photoconductor 10 is uniformly charged by the charging device 11. Next, the laser writing is performed by irradiating the photoconductor 10 with laser light from the laser writing device 47 in accordance with the content of the document read by the above-described scanner 200, and an electrostatic latent image is formed on the surface of the photoconductor 10. After that, toner is adhered to the electrostatic latent image on the surface of the photoreceptor 10 by the developing device 12 to visualize the image.

  In the copying machine 500, at the same time when the start switch is pressed, the recording paper P is sent out from the plurality of recording paper cassettes 61 provided in the paper feeding unit 300 by the calling roller 62 from the one corresponding to the selected size. Then, the fed recording paper P is separated one by one by a supply roller 63 and a separation roller 64, and one of the sheets is guided to a supply path R1 and guided to a recording paper transport path R by a pair of recording paper transport rollers 66. . The recording paper P conveyed to the recording paper conveyance path R abuts against the registration roller pair 21 and is stopped.

  When the manual paper feed unit 68 is used, the manual paper tray 67 is opened and the recording paper P is set therein. Also in this case, the recording paper P set on the manual feed tray 67 is conveyed by the call roller 62, the supply roller 63, and the separation roller 64 to the manual feed path R2, and the recording paper is conveyed by the recording paper conveyance roller pair 66. Guided to road R. The recording paper P guided to the recording paper conveyance path R abuts against the registration roller pair 21 and is stopped.

The recording paper P stopped by the registration roller pair 21 is transferred by the registration roller pair 21 which starts rotating at the timing when the leading end of the visualized toner image of the photoconductor 10 enters the transfer position B. It is sent to position B.
The toner image on the photoreceptor 10 is transferred to the recording paper P sent to the transfer position B by the transfer unit 13, and the toner image is carried on the surface thereof. The toner remaining on the surface of the photoconductor 10 after the transfer is removed by the cleaning device 14, the surface of the photoconductor 10 is discharged by the discharge lamp, and the photoreceptor 10 is ready for the next image formation starting from the charging device 11.

  On the other hand, the recording paper P carrying the toner image at the transfer position B is conveyed by the transfer belt 17 and enters the fixing device 22. Then, heat and pressure are applied while being conveyed between the heating roller 30 and the pressure roller 32, and the toner image on the recording paper P is fixed. Thereafter, the recording paper P is discharged from the discharge port 40 onto the discharge stack section 39 by the discharge roller pair 35, and is stacked there.

  When images are formed on both sides of the recording paper P, the discharge branch claws 34 are switched, and the toner image is transferred and fixed on one side of the recording paper P. Then, the recording paper P is transferred from the recording paper conveyance path R to the reversing path. Put in R3. The recording paper P put in the reversing path R3 is conveyed by the recording paper conveyance roller pair 66 to enter the switchback position 44, and then is switched back by the switchback roller pair 43. The sheet is again guided to the recording sheet conveyance path R by the sheet conveyance roller pair 66. Then, the toner image is transferred to the opposite surface of the recording paper P passing through the re-conveying path R4 in the same manner as described above.

Inside the image forming unit 100, various sounds such as a driving sound of a driving motor for transmitting rotational driving to various rollers, a moving sound of a moving member such as various rollers, and a rotating sound of a polygon mirror 48 of the laser writing device 47. Occurs. Such a sound may be transmitted to the outside of the copying machine 500, and may be discomfort to nearby people.
In the copying machine 500 according to the present embodiment, the sound absorbing device is fixed to an exterior cover forming a housing of the image forming unit 100. As the exterior cover for fixing the sound absorbing device, there are a rear exterior cover close to the drive unit on the rear side in FIG. 2 where the drive motor is arranged and a front exterior cover on the near side in FIG. 2. It is not limited. Further, the sound absorbing device may be fixed not only to the outer cover but also to a member inside the housing such as an inner cover.

FIG. 3 is an explanatory diagram schematically showing the sound absorbing device 600 included in the copying machine 500 of the present embodiment.
The sound absorbing device 600 is a communication portion forming plate that is a first member that forms an opening forming surface 620f provided with a communication portion 602 that communicates the cavity portion 601 with the outside of the wall surface forming the cavity portion 601 of the Helmholtz resonator. 620. Further, the sound absorbing device 600 includes a cavity forming member 610 as a second member that forms another wall surface (the bottom surface 613f and the side wall surface 611f) of the cavity portion 601. The material of the cavity forming member 610 is a resin, a material having a lower density than that of the metal that is the material of the communication portion forming plate 620, and is easily processed.

  In the sound absorbing device 600 shown in FIG. 3, the volume of the cavity 601 is “V”, the opening area of the communication part 602 is “S”, the length of the communication part 602 in the communication direction is “H”, and the sound speed is “c”. If the sound absorbing frequency of the sound absorbing device 600 is “f”, the following expression (1) is established.

  As shown in the above formula (1), the frequency of the sound absorbed by the sound absorbing device 600 depends on the volume “V” of the cavity 601, the length “H” of the communication portion 602, and the opening area “S” of the communication portion 602. You can ask.

The communication portion forming plate 620 has a flange portion 621 formed by burring, and the inside of the flange portion 621 becomes a communication portion 602 having a cross-sectional area “S” and a length “H”. The communication portion forming plate 620 and the cavity forming member 610 are closely attached by screws. The volume of the cavity 601 formed by the cavity forming member 610 is “V”.
Burring is a processing method in which a hole called a pilot hole is made in a plate material, a punch larger in diameter than the pilot hole is pushed into the pilot hole, the edge of the pilot hole is expanded, and a flange is formed around the opening. is there. By forming the communication portion 602 by burring, the communication portion can be formed without separately providing a member for forming the communication portion 602 with respect to the communication portion forming plate 620 which forms a part of the wall surface forming the hollow portion 601. 602 can be formed.

The sound absorbing device 600 shown in FIG. 3 arranges the opening of the communication portion 602 so as to face the sound source of the sound to be absorbed. Thus, the sound to be absorbed enters the communication portion 602, and a sound absorbing effect can be obtained. The flange portion 621 provided to rise in the communication direction with respect to the plate-shaped portion of the communication portion forming plate 620 is a standing portion forming the communication portion 602. In the sound absorbing device 600 shown in FIG. A flange portion 621 is provided to stand outward from the portion 601.
Also, the larger the difference between the diameter of the pilot hole and the diameter of the punch hole, the higher the flange portion 621, and the longer the length "H" of the communication portion 602 inside the flange portion 621. Therefore, by adjusting the difference between the diameter of the pilot hole and the diameter of the punch hole, the height of the flange portion 621 can be adjusted, and the value of the length “H” of the communication portion 602 can be adjusted.

  In the sound absorbing device 600 shown in FIG. 3, since the communication portion forming plate 620 is made of a material having a higher density than the cavity forming member 610, transmitted sound can be suppressed as compared with a configuration formed using only the material of the cavity forming member 610. . In addition, since the cavity forming member 610 is made of a material having a lower density than the communicating portion forming plate 620, it is easier to process than the communicating portion forming plate 620, and maintains the airtightness compared to the configuration formed only with the communicating portion forming plate 620. In addition, the volume of the cavity 601 can be secured with high accuracy. By securing the volume of the cavity 601, low frequency sound can be absorbed, and the sound absorbing effect can be improved by forming the cavity 601 with high precision while maintaining the airtightness. Thus, in the sound absorbing device 600, it is possible to enhance the sound absorbing effect on low frequency sound while suppressing transmitted sound.

In the sound absorbing device 600 having the structure of the Helmholtz resonator, in order to obtain a desired sound absorbing effect, the cavity 601 needs to be sealed from the outside except for the opening by the communicating portion 602. Therefore, it is necessary to form a boss (positioning convex portion) for positioning the metal communication portion forming plate 620 and a screw fixing portion (screw hole portion) for fixing the metal communication portion forming plate 620 on the resin-made cavity forming member 610. .
In the schematic diagram of the sound absorbing device 600 shown in FIG. 3, a boss for positioning the communicating portion 602 and the cavity 601 and a positioning portion such as a screwing portion for fixing are not described.

In order for the sound absorbing device 600 to absorb a desired frequency, the values of “V”, “H” and “S” on the right side are appropriately adjusted so that “f” on the left side of the above equation (1) becomes a desired value. Must be set to
Since the communicating portion 602 is formed by burring, the opening area “S” and the length “H” in the communicating direction can be easily obtained.

  However, calculation of the volume “V” of the cavity 601 may be complicated depending on the arrangement of the positioning unit. For example, if the positioning unit is arranged in the cavity 601, the calculation becomes complicated. Further, in the sound absorbing device 600 including a plurality of Helmholtz resonator structures each including a combination of the cavity 601 and the communication portion 602, the positioning portion is configured by considering only the hermeticity between the cavity forming member 610 and the communication portion forming plate 620. The following inconveniences may occur when the is arranged. That is, among the plurality of cavities 601, the volume of the cavity 601 in which the positioning portion is disposed and the volume of the cavity 601 in which the positioning portion is not disposed are different. 601 may have different volumes.

In such a case, in order to absorb sound of a single frequency in the plurality of hollow portions 601, the opening area “S” and the length “H” of the communication portion 602 must be set for each Helmholtz resonator structure. It is necessary to adjust the shape so as to make it different, which complicates the design.
Hereinafter, the details of the sound absorbing device 600 of this embodiment including the positioning portion will be described with reference to FIG.

FIG. 1 is an explanatory perspective view of a sound absorbing device 600 included in a copying machine 500 of the present embodiment. FIG. 1A is a perspective view illustrating a state in which the communication portion forming plate 620 is fixed to the cavity forming member 610, and FIG. 1B illustrates a state in which the communication portion forming plate 620 is changed from the state illustrated in FIG. It is a perspective explanatory view of the cavity formation member 610 in the state removed.
In the sound absorbing device 600 shown in FIG. 1, since the flange portion 621 is formed so as to extend toward the inside of the hollow portion 601, the flange portion 621 shown in the schematic diagram of FIG. 3 is shown in FIG. Absent.

  As shown in FIG. 1B, the cavity forming member 610 connects the bottom plate 613 facing the communicating portion forming plate 620 with the cavity 601 interposed therebetween, and connects between the communicating portion forming plate 620 and the bottom plate 613. And a side wall forming portion 611 extending likewise. The outline of the cavity 601 is a regular hexagonal prism so that the outline of the cross section of the plurality of cavities 601 formed in the cavity forming member 610 is a regular hexagon, and all the vertices of the regular hexagon of the section are circular. A columnar column 612 is provided. Further, a positioning convex portion 615 for positioning the cavity forming member 610 and the communication portion forming plate 620 and a screw hole portion 616 for performing screw fastening are formed on the surface of the columnar portion 612 on the side of the communication portion forming plate 620.

With such a configuration, the volumes of the plurality of hollow portions 601 can be uniformly calculated, and a device that absorbs sound of a target frequency can be easily designed and created.
Specifically, the volume of the hollow portion 601 can be easily reduced by subtracting the volume of the columnar portion 612 at the six vertexes (the volume of the columnar shape having a fan-shaped cross section) from the volume of the regular hexagonal column without the columnar portion 612. Can be calculated. Then, the sound absorption frequency can be easily calculated by substituting the value of the volume into the above equation (1).

By making the shape of the cavity 601 a regular polygon, such as a regular hexagon, the area of the regular polygon can be easily calculated based on the length of one side. By multiplying the height, the volume of the approximate columnar space of the cavity 601 can be easily calculated. The volume of the hollow portion 601 can be calculated by subtracting the volume of the columnar portion 612 that has entered the vertex of the polygon from the volume of the columnar space.
In addition, by making the shape of the hollow portion 601 a regular polygon such as a regular hexagon, the fan-shaped shape in which the columnar columnar portion 612 enters at all vertices becomes the same, and the volume of the hollow portion 601 can be easily calculated. Becomes

  In the sound absorbing device 600 according to the present embodiment, the plurality of hollow portions 601 are formed to have the same regular polygonal cross section, and the same columnar portion 612 is disposed at all the vertices. The volume of 601 is unified. This facilitates the design of the sound absorbing device 600 that absorbs sound of the same frequency with the structure of a plurality of Helmholtz resonators, and efficiently reduces noise when the frequency of the sound that causes noise is specified. It becomes possible to suppress.

In addition, by making the shape of the hollow portion 601 a polygon, the plate-like portion (wall plate portion 614) forming the side becomes linear. In addition, the wall portion 614 can be shared with a plate-shaped portion forming the side of another adjacent hollow portion 601, and a plurality of hollow portions 601 can be arranged without gaps.
In addition, among the regular polygons, a regular triangle, a square, and a regular hexagon make it possible to arrange the cavity 601 having the same shape without a gap, and the cavity 601 can be efficiently arranged in the installation space. The sound absorbing effect can be improved.

  When assembling the sound absorbing device 600 of the present embodiment, the two positioning protrusions 615 raised on the cavity forming member 610 are inserted into positioning holes provided in the communication portion forming plate 620, and are parallel to the surface of the communication portion forming plate 620. The positioning of the cavity forming member 610 and the communication portion forming plate 620 in the directions is performed. Thus, the plurality of screw holes 616 of the communication portion forming plate 620 and the plurality of screw through holes provided in the communication portion forming plate 620 face each other. Next, the cavity forming member 610 and the communication portion forming plate 620 are fixed by passing the screws 630 through the plurality of screw through holes and fastening the screws to the screw holes 616.

  When the sound absorbing device 600 is fixed to the outer cover, the bottom plate 613 of the cavity forming member 610 is disposed so as to face the inner wall surface of the outward cover, and the communication portion 602 is located inside the device in which a drive motor or the like serving as a sound source is disposed. Open toward.

  Here, a temporary configuration in which the columnar portion 612 is not provided at a portion forming the vertex of the polygon will be described. In a plate-like portion forming a polygonal side in the side wall forming portion 611 like the wall plate portion 614, the width can be made constant and the thickness can be made constant. On the other hand, the vertices of the side wall forming portion 611 where the sides intersect each other have a greater thickness than the side portions. If this is to be formed by injection molding of a resin, sink is likely to occur at a vertex where the wall thickness is larger than other portions, and a manufacturing error is likely to occur. Even if the configuration does not include the columnar portion 612, a positioning portion with the communication portion forming plate 620 such as the positioning protrusion 615 and the screw hole 616 is required. Even if the positioning portion is provided separately from the portion forming the polygon, the shape is more complicated than the plate-shaped portion, and manufacturing errors are likely to occur.

  In the sound absorbing device 600 according to the present embodiment, by disposing the positioning portion at the vertex of the polygon in the side wall forming portion 611, it is possible to suppress a shape in which a manufacturing error is likely to be dispersed, and to suppress a manufacturing error in the entire sound absorbing device 600. Suppress. Thus, the variation in the volume of the cavity 601 due to the manufacturing error can be suppressed, the accuracy of setting the sound absorbing frequency of the sound absorbing device 600 to a desired frequency can be improved, and the sound absorbing effect can be improved.

Further, as described above, since the calculation of the volume of the cavity 601 is easy, the calculation of the sound absorbing frequency of the sound absorbing device 600 becomes clear, and the variation in the sound absorbing effect with respect to the frequency of the sound to be absorbed is suppressed, and the noise is reduced. Can be.
Further, by uniformly calculating the volumes of the plurality of hollow portions 601, it becomes easy to design the sound absorbing device 600 having the structure of the plurality of Helmholtz resonators.

As a configuration for suppressing the production error of the hollow portion 601 due to the production error of the positioning portion, a columnar portion is provided separately from a portion of the cavity forming member 610 that forms the side wall of the cavity portion 601. It is conceivable to provide a positioning portion on the rim.
However, as shown in FIG. 1, in a configuration in which a plurality of cavities 601 are arranged side by side, if a positioning portion is provided outside a portion where the cavities 601 are formed, the cavities 601 surrounded by the other cavities 601 can be formed. The distance from the positioning part is increased. As a result, a gap is formed between the side wall forming portion 611 forming the hollow portion 601 and the communication portion forming plate 620 due to the warpage of the member, vibration at the time of driving, or the like, so that the airtightness of the hollow portion 601 cannot be maintained, and the sound absorbing performance is not maintained. May decrease.

  On the other hand, by arranging the columnar portion 612 on which the positioning portion can be provided at the vertex of the polygon, the hollow portion 601 among the plurality of hollow portions 601 surrounded by the other hollow portions 601 can be used. , It is possible to dispose the positioning portion in the vicinity, and it is possible to maintain the hermeticity. By maintaining the airtightness of the cavity 601, desired sound absorbing performance can be exhibited.

  In the sound absorbing device 600 shown in FIG. 1, a screw hole 616 is formed on a surface of the columnar portion 612 on the communication portion forming plate 620 side of all the columnar portions 612 except for the two columnar portions 612 provided with the positioning projection 615. Provided. By arranging many screw holes 616, the sealing performance can be improved. However, if the number of screw holes 616 is large, the number of necessary screws increases, the number of parts increases, and the number of screw tightening steps also increases.

  The communication portion forming plate 620 made of a sheet metal has high rigidity and is unlikely to float due to deformation of the member. Therefore, as long as airtightness can be ensured, a configuration may be adopted in which some of the plurality of columnar portions 612 do not have any positioning portion such as the screw hole portion 616 or the positioning convex portion 615. That is, if the airtightness can be maintained, it is not necessary to screw all of the columnar portions 612 where the positioning convex portions 615 are not provided, and the screw fixing portions can be determined according to the peripheral layout. Thereby, even if the columnar portions 612 are provided at all the vertices of the configuration having a plurality of polygonal hollow portions 601 having a large number of vertices, the number of screw holes 616 can be reduced, and the number of parts can be reduced. It is possible to suppress the increase and the man-hour increase.

  Since the columnar portions 612 are provided at the vertices of the polygon and it is possible to appropriately select whether or not to provide the positioning portion for each of the plurality of columnar portions 612, the number and location of the screws 630 that can maintain the airtightness are set. It becomes possible. As a result, the layout can be made more cost-effective and more efficient.

  The portion forming the columnar portion 612 in the side wall forming portion 611 of the present embodiment has a shape thicker than the wall plate portion 614 which is a plate-like portion forming a polygonal side in the side wall forming portion 611. I have. Thus, the screw holes 616 and the positioning protrusions 615 that require a certain width are arranged in the columnar portion 612, and the thickness of the wall plate portion 614 in the side wall forming portion 611 can be reduced. By reducing the thickness of the wall plate portion 614, a resin material necessary for forming the hollow portion 601 can be reduced. Further, when the thickness of the wall plate portion 614 is increased to a thickness (thickness of the columnar portion 612) enough to form the positioning portion, the sound absorbing device 600 can be enlarged when the same number of hollow portions 601 having the same volume are arranged. Connect. On the other hand, by making the thickness of the wall plate portion 614 thinner than the thickness of the columnar portion 612 provided with the positioning portion, the overall size of the sound absorbing device 600 can be reduced.

  Further, when the wall plate portion 614 is thickened, the wall plate portion 614 becomes thick, sink marks are likely to occur, and there is a possibility that a manufacturing error in the volume of the hollow portion 601 may increase. On the other hand, by making the wall plate portion 614 thin, it is possible to suppress the occurrence of sink marks in this portion, and to suppress the manufacturing error of the volume of the hollow portion 601. Therefore, the accuracy of setting the sound absorbing frequency of the sound absorbing device 600 to a desired frequency is improved, and the sound absorbing effect can be improved.

  Further, the cavity forming member 610 of the present embodiment has a shape in which a concave portion called “lightening” or “thief” is formed on the back side of the columnar portion 612. Accordingly, it is possible to suppress the cavity forming member 610 from being thick at the columnar portion 612 having a thickness greater than that of the wall plate portion 614, and to suppress generation of sink in the columnar portion 612. This makes it possible to suppress a manufacturing error in the volume of the cavity 601. Therefore, the accuracy of setting the sound absorbing frequency of the sound absorbing device 600 to a desired frequency is improved, and the sound absorbing effect can be improved.

  By suppressing the occurrence of sink marks in the cavity forming member 610, the smoothness of the surface of the side wall forming portion 611 of the cavity forming member 610 that contacts the communication portion forming plate 620 is improved. Thereby, formation of a gap between the cavity forming member 610 and the communication portion forming plate 620 can be suppressed, and the hermeticity of the cavity 601 can be improved.

  In the sound absorbing device 600 having the structure of the Helmholtz resonator, the sound incident on the communication portion 602 is absorbed. Since the sound that has not entered the communication part 602 enters the outer wall surface around the opening of the communication part 602, the wall on which the communication part 602 is provided among the walls forming the surface around the hollow part 601 is: A metal (sheet metal) excellent in suppressing transmitted sound is desirable.

  When sound is incident on a wall, the greater the mass of the wall per unit area, the greater the sound transmission loss (the more difficult the sound is to transmit). When the material of the wall is uniform, sound becomes more difficult to transmit as the thickness of the wall increases and the density (mass per unit volume) of the material forming the wall increases. Therefore, among the walls forming the cavity 601, the transmission of the sound can be suppressed by forming the wall provided with the communication portion 602 from a metal sheet metal having a higher density than the resin. Further, in the case of a sheet metal, the sound striking the side facing the sound source side is difficult to transmit and the amount of reflection is large, so that the amount of sound reflected toward the communication portion 602 is relatively increased, and the sound absorbing effect is improved. be able to.

In the sound absorbing device 600, a member forming a surface around the cavity 601 other than the surface provided with the communication portion 602 is a resin cavity forming member 610, and a member serving as a lid forming the communication portion 602 is a sheet metal. And a communication portion forming plate 620 made of By forming the surface around the cavity 601 with the cavity forming member 610, the volume of the cavity 601 can be increased, and the frequency of the sound to be absorbed can be set to a low frequency.
An iron plate such as a galvanized steel plate can be used as the sheet metal, but a plate made of another metal such as aluminum may be used. As the resin material used for the cavity forming member 610, polycarbonate or ABS resin can be used, but is not limited thereto. For example, synthetic or natural rubber can be used.

  In the sound absorbing device 600 of the present embodiment, the cavity forming member 610 that forms the surface around the cavity 601 is formed of resin. A resin component, which is a material that is easier to process than metal, can be accurately molded into a desired shape by pouring the material into a mold. Therefore, in the sound absorbing device 600 of the present embodiment, it is possible to sufficiently secure the volume of the hollow portion 601 with high accuracy while maintaining the airtightness.

FIG. 4 is a perspective explanatory view of an example of the cavity forming member 610 in which the cross-sectional shape of the cavity 601 is a regular triangle.
In the cavity forming member 610 shown in FIG. 4, the plurality of cavities 601 are formed so that the general shape is a regular triangular prism, and the columnar portions 612 are provided at all vertexes of the regular hexagon of the cross section. Further, a positioning convex portion 615 for positioning the cavity forming member 610 and the communication portion forming plate 620 and a screw hole portion 616 for performing screw fastening are formed on the surface of the columnar portion 612 on the side of the communication portion forming plate 620.

FIG. 5 is a perspective explanatory view of an example of the cavity forming member 610 in which the outline of the cross section of the cavity 601 is a regular hexagon and a regular triangle.
In the cavity forming member 610 shown in FIG. 5, a plurality of hexagonal cavity portions 601a whose outline shape is a regular hexagonal prism and a plurality of triangular cavity portions 601b whose outline shape is a regular triangular prism are formed. The columnar portions 612 are provided at all vertexes of the regular hexagon of the cross section of the hexagonal cavity 601a and the regular triangle of the cross section of the triangular cavity 601b. Further, a positioning convex portion 615 for positioning the cavity forming member 610 and the communication portion forming plate 620 and a screw hole portion 616 for performing screw fastening are formed on the surface of the columnar portion 612 on the side of the communication portion forming plate 620.

  Since the cavity forming member 610 made of resin has good workability, it is conceivable that a change in shape is required for the convenience of the peripheral layout. In the above-described configuration in which the shape is adjusted so that the opening area “S” and the length “H” of the communication portion 602 are different for each structure of the Helmholtz resonator, each time a shape change is required, individual It is necessary to recalculate the volume of the cavity 601.

  Even when a space in which the hexagonal cavity 601a cannot be arranged occurs due to the shape change, as shown in FIG. 5, the space required for the arrangement is smaller than that of the hexagonal cavity 601a. Can be used efficiently. When the triangular hollow portion 601b and the hexagonal hollow portion 601a absorb the same frequency sound, the length “H” of the communication portion 602 and the opening area “S” of the communication portion 602 are adjusted. This makes it possible for the triangular cavity 601b and the hexagonal cavity 601a having different volumes to absorb sounds of the same frequency.

  The plurality of hexagonal hollow portions 601a are all of the same shape, and the plurality of triangular hollow portions 601b are all of the same shape. By preparing a plurality of types of polygonal column-shaped hollow portions 601 thus uniformized, even if the space in which the large-volume hollow portion 601 can be arranged is lost due to the shape change, the volume is known in advance. The cavity 601 having a small volume can be arranged. This eliminates the need to recalculate the volume of the cavity 601 even when a shape change is requested, and can reduce the calculation load.

In the embodiment, by combining a communicating portion forming plate 620 as a first member having an opening forming portion, and a cavity forming member 610 as a second member having a side wall forming portion 611 and a bottom plate portion 613 as an opening facing portion. The configuration for forming the sound absorbing device 600 has been described. As a combination of the first member and the second member, the first member may have the opening facing portion, and the second member may have the opening forming portion and the side wall forming portion. In the case of this configuration, the second member has a configuration in which the side wall forming portion 611 is provided on the communication portion forming plate 620, but the second member is formed of a resin material including the flange portion 621 forming the communication portion 602. By doing so, such a configuration can also be realized.
Further, the sound absorbing device is formed by fixing the member having the opening forming portion and the member having the opening facing portion to the member having the side wall forming portion by using the opening forming portion, the side wall forming portion, and the opening facing portion as separate members. 600 may be formed.

  In the above-described embodiment, the case where the outline of the cavity 601 is a regular prism is described. The general shape of the hollow portion 601 is not limited to this, and may be a prism having a columnar portion 612 thicker than the wall plate portion 614 at a vertex of a polygon of a cross section. Furthermore, as long as the columnar portion 612 is provided at the vertex of the polygon of the cross section, the surface of the cavity forming member 610 and the surface of the bottom plate portion 613 are not limited to the rectangular parallelepiped, and the surface of the cavity forming member 610 is not limited thereto. And the surface of the bottom plate 613 may be inclined.

  The shape of the columnar portion 612 is not limited to a columnar shape, and may be a prism. In the case where the columnar portions 612 are arranged at a plurality of vertexes of the polygon of the cross section of the cavity 601, the volume of the columnar portions 612 at the vertexes at which the columnar portions 612 are arranged is the same, so that the volume of the cavity 601 can be calculated. It will be easier. By making the plurality of columnar portions 612 into a columnar shape having the same diameter and making the approximate polygon of the cross section of the hollow portion 601 into a regular polygon, it becomes easy to calculate the volume at which the columnar portion 612 enters at the above-described apex, Calculation of the volume of the part 601 becomes easy.

  In the present embodiment, the case where the electronic apparatus including the sound absorbing device is an image forming apparatus has been described. However, the electronic device may include a sound source unit that generates a sound during operation and a sound absorbing device that absorbs a sound emitted from the sound source unit. For example, the present invention is applicable to electronic devices other than the image forming apparatus.

  What has been described above is merely an example, and each embodiment has a specific effect.

(Aspect A)
In a sound absorbing device such as a sound absorbing device 600 including a cavity such as a cavity 601 and an opening such as a communication portion 602 that communicates the cavity with the outside, an opening forming surface such as an opening forming surface 620f having an opening formed therein. Alternatively, the first member such as the communication portion forming plate 620 having one of the opening facing surfaces such as the bottom surface 613f opposed to the opening forming surface across the hollow portion is connected to the opening forming surface and the opening facing surface. A cavity is formed by combining a cavity forming member 610 having at least a side wall forming portion such as a side wall forming portion 611 forming a side wall surface such as an extending side wall surface 611f to form a cavity. The shape of the side wall surface as viewed from the side or the opening opposing surface side is a polygon such as a regular hexagon, and at least one of the portions forming the vertices of the polygon in the side wall forming portion is positioned with the first member. Screw hole 6 6 and a positioning portion such as a columnar portion 612 for arranging the positioning convex portion 615 and the like, and the thickness of the plate-like portion such as the wall plate portion 614 forming the polygonal side in the side wall forming portion is larger than the thickness of the positioning portion. thin.
According to this, as described in the above embodiment, it is possible to form the cavity of the sound absorbing device with high accuracy. This is for the following reason.
That is, in the sound absorbing device described in Patent Literature 1, a positioning portion is provided at a portion forming a quadrangular vertex in a side wall forming portion, a thickness of the side wall forming portion is made constant, and a plate forming a polygonal side in the side wall forming portion is provided. The thickness of the shape portion is the same as the thickness of the positioning portion. When the second member having such a side wall forming portion is formed by injection molding, the plate-shaped portion is more likely to have sink marks as the thickness is larger, and the thickness of the positioning portion having a thickness necessary for arranging the shape to be positioned. When the thickness of the plate-shaped portion is the same as that of the plate-shaped portion, sinks tend to occur in the plate-shaped portion. If sinks occur in the plate-like portion, manufacturing errors in the cavity may increase, and the sound absorbing effect of sound of a desired frequency may be reduced.
On the other hand, in the aspect A, by making the thickness of the plate portion smaller than the thickness of the positioning portion, it is possible to suppress the occurrence of sink marks in the plate portion and suppress the manufacturing error of the hollow portion. . Therefore, it is possible to form the cavity of the sound absorbing device with high accuracy, and to improve the sound absorbing effect of the sound of the desired frequency.

(Aspect B)
In the embodiment A, the shape of the side wall surface such as the side wall surface 611f viewed from the side of the opening forming surface such as the opening forming surface 620f or the side of the opening facing surface such as the bottom surface 613f is a regular polygon.
According to this, as described in the above embodiment, the calculation of the volume of the cavity becomes easy.

(Aspect C)
In the embodiment A or B, a plurality of combinations of a cavity such as the cavity 601 and an opening such as the communication portion 602 are provided.
According to this, as described in the above embodiment, it is possible to provide the positioning portion near each of the cavities, and it is possible to maintain the hermeticity of each of the cavities.

(Aspect D)
In Embodiment C, at least one of the portions forming the vertices of a polygon such as a regular hexagon in the side wall forming portion such as the side wall forming portion 611 has a columnar portion such as the columnar portion 612 thicker than the plate portion such as the wall plate portion 614. And at least one of the columnar portions is provided with a positioning portion such as a screw hole portion 616 and a positioning convex portion 615, and the columnar portions provided in each of the plurality of hollow portions such as the plurality of hollow portions 601 have the same shape ( Etc.).
According to this, as described in the above embodiment, it is easy to calculate the volume of the columnar portion that enters the portion forming the vertex of the polygon in the hollow portion, and it is easy to calculate the volume of the hollow portion.

(Aspect E)
In the aspect C or D, the volumes of the cavities such as the plurality of cavities 601 are the same.
According to this, as described in the above embodiment, it is possible to uniformly calculate the volumes of a plurality of cavities by forming the cavities having the same volume with high accuracy, and to achieve the target frequency. It is possible to easily design and create a device that absorbs the sound of the sound.
Further, when the positioning portion is formed only in a part of the plurality of cavities, it is difficult to maintain the same volume among the plurality of cavities. On the other hand, in the aspect E, a columnar portion on which the positioning portion can be disposed is provided in each of the plurality of hollow portions, and whether or not the positioning portion is disposed is appropriately selected. This prevents the plurality of cavities from having different shapes depending on whether or not the positioning portion is provided, and facilitates maintaining the same volume among the plurality of cavities.

(Aspect F)
In any one of Aspects A to E, the positioning portion includes a projection such as a positioning projection 615 inserted into a hole such as a positioning hole provided in a first member such as the communication portion forming plate 620, or a first member. And a screw fixing portion such as a screw hole 616 for screw fixing.
According to this, as described in the above embodiment, it is possible to realize a configuration in which the second member such as the cavity forming member 610 and the first member are positioned and the sound absorbing device such as the sound absorbing device 600 is assembled. Becomes

(Aspect G)
In an electronic apparatus such as a copying machine 500 provided with a sound absorbing unit that absorbs sound during operation, a sound absorbing device such as the sound absorbing device 600 according to any one of modes A to F is provided as the sound absorbing unit.
According to this, as described in the above embodiment, by providing the sound absorbing device capable of improving the sound absorbing effect, it is possible to more effectively absorb the sound generated during the operation of the electronic device.

(Aspect H)
In an image forming apparatus such as a copying machine 500 provided with a sound absorbing unit that absorbs sound during operation, a sound absorbing device such as the sound absorbing device 600 according to any one of modes A to F is provided as the sound absorbing unit.
According to this, as described in the above embodiment, by providing the sound absorbing device capable of improving the sound absorbing effect, it is possible to more effectively absorb the sound generated during the operation of the image forming apparatus. .

Reference Signs List 10 photoconductor 11 charging device 12 developing device 13 transfer unit 17 transfer belt 20 toner replenishing device 21 registration roller pair 22 fixing device 39 discharge stack unit 47 laser writing device 48 polygon mirror 49 polygon motor 100 image forming unit 200 scanner 300 paper feed Unit 400 Automatic Document Feeder 500 Copier 600 Sound Absorber 601 Cavity 601a Hexagonal Cavity 601b Triangular Cavity 602 Communication Portion 610 Cavity Forming Member 611 Sidewall Forming 611f Sidewall 612 Columnar 613 Bottom Plate 613f Bottom Plate 614 Wall Plate 615 Positioning convex portion 616 Screw hole portion 620 Communication portion forming plate 620f Opening forming surface 621 Flange portion 630 Screw

JP 2009-139556 A

Claims (8)

A cavity,
In the sound absorbing device comprising an opening communicating the cavity with the outside,
A first member having one of an opening forming surface in which the opening is formed or an opening facing surface opposed to the opening forming surface across the cavity is connected between the opening forming surface and the opening facing surface. And the second member having at least a side wall forming portion forming a side wall surface extending so as to form the hollow portion,
The outline of the cavity defined by the side wall surface viewed from the opening forming surface side or the opening facing surface side is a polygon,
Wherein among the columnar portion component corresponding to the vertex of the polygons in the side wall forming portions, Rutotomoni provided positioning portion for positioning said first member to a portion of the columnar portion, the first member to another post portion A fixing part for fixing with
The thickness of the plate-like portion corresponding to the polygonal sides of the side wall forming portions, the sound absorbing device, wherein a thin by the thickness remote of the columnar portion. The sound absorbing device according to claim 1,
The polygon sound absorber which is a positive polygonal. The sound absorbing device according to claim 1 or 2,
A sound absorbing device comprising a plurality of combinations of the cavity and the opening. The sound absorbing device according to claim 3,
Absorbing and wherein the shape of the columnar portion component provided in each of the plurality of the cavities are the same shape as each other. The sound absorbing device according to claim 3 or 4,
A sound absorbing device, wherein the plurality of hollow portions have the same volume. The sound absorbing device according to any one of claims 1 to 5,
The positioning portion is a convex portion that is inserted into a hole provided in the first member,
The sound absorbing device according to claim 1 , wherein the fixing portion is a screw fixing portion for fixing the screw to the first member. In an electronic device having a sound absorbing means for absorbing a sound during operation,
An electronic apparatus comprising the sound absorbing device according to claim 1 as the sound absorbing means. In an image forming apparatus including a sound absorbing unit that absorbs sound during operation,
An image forming apparatus comprising the sound absorbing device according to any one of claims 1 to 6 as the sound absorbing means.

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