JP2018097098A - Cover member, image formation device using the same, and cover member manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cover member in which a thin and light-weight vibration damping sheet is not closely contact with an entire cover surface in a state of having no gap and which can reduce a radiation sound with a simple configuration, an image formation device using the cover member, and a cover member manufacturing method.SOLUTION: A cover member including an outer wall surface and an inner wall surface for covering an opening of an image formation device body includes: a vibration damping sheet facing the inner wall surface for damping vibration of the image formation device body; a fixing section for fixing the vibration damping sheet to the inner wall surface at a first position in a first direction; and a tensile force applying section for fixing the vibration damping sheet at a second position different from the first position in the first direction and applying tensile force to the vibration damping sheet without making the whole surface of the vibration damping sheet in close contact with the inner wall surface.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cover member used in an image forming apparatus for forming an image such as a printer or a copying machine, an image forming apparatus using the same, and a method for manufacturing the cover member.

  In an image forming apparatus main body in an image forming apparatus such as a copying machine, components such as a laser scanner unit, a motor, a solenoid, and a clutch that operate intermittently or regularly during image formation are used. These parts generate a considerable amount of sound during their operation. Further, the vibration generated by these components may cause the surrounding components to resonate and generate sound. Further, when a sheet such as a recording sheet is conveyed in the image forming apparatus main body, there is a sound generated due to rubbing, buckling, striking, or the like of the sheet.

  When such a device is operating, there are many components with a frequency of about 1 kHz or less, and depending on the level of the sound pressure level in that frequency band, it may be very harsh to the operator of the device and those in the vicinity. There is. Therefore, measures are taken to reduce the noise by suppressing the noise itself generated in the image forming apparatus main body, or suppressing the noise generated in the image forming apparatus main body from leaking out of the image forming apparatus main body. ing.

  A measure for suppressing sound leakage outside the image forming apparatus main body is usually performed by insulating the sound with an exterior cover. Generally, a resin material is employed for the exterior cover from the viewpoint of weight reduction and low cost. Although it has a function of suppressing noise to some extent, there is a case where the exterior cover itself vibrates due to vibration or noise generated in the image forming apparatus main body, thereby generating radiated sound. In order to insulate the noise transmitted through the exterior cover to the extent that there is no problem, it is necessary to increase the thickness of the exterior cover to some extent, which is not a practical measure from the viewpoint of weight and cost.

  Therefore, in Patent Document 1, the Helmholtz resonator is integrated with the exterior cover to suppress vibration transmission and acoustic radiation from the exterior surface. Moreover, in patent document 2, the fibrous sound-absorbing material which has a sound-absorbing function in the audible sound frequency area | region is affixed on the inner surface of the exterior cover surrounding a device. On the other hand, Patent Document 3 proposes a structure that reduces vibration of a panel by using a thin and light damping sheet. This is to reduce vibration by bringing the damping sheet into close contact with the entire surface of the roof panel and integrating them with no gap between the opposing surfaces of the panel.

JP 2000-235369 A JP 2002-365985 A JP 2008-179343 A

  However, in Patent Documents 1 and 2, the formation of a resonance space for sound absorption and the use of a sound absorbing material make the outer cover of the image forming apparatus thick. Further, in Patent Document 3, when a structure using a thin and lightweight vibration damping sheet is applied to an exterior cover, a large amount is required because the vibration damping sheet is used in close contact with the entire surface of the cover. Furthermore, an uneven surface such as a rib exists on the inner surface of the image forming apparatus, and it is difficult to make the vibration damping sheet adhere to the surface without a gap.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a cover member capable of reducing a radiated sound with a simple configuration without closely attaching a thin and lightweight vibration damping sheet to the entire cover surface without a gap, and an image forming apparatus using the same. It is providing the manufacturing method of a cover member.

  In order to achieve the above object, a cover member according to the present invention is a cover member that includes an outer wall surface and an inner wall surface and covers an opening in the image forming apparatus main body, and is opposed to the inner wall surface and vibrates in the image forming apparatus main body. A damping sheet for damping the damping sheet, a fixing portion for fixing the damping sheet to the inner wall surface at a first position in a first direction, and the first position in the first direction. And a tension applying portion that applies tension to the damping sheet without bringing the damping sheet into close contact with the entire inner wall surface.

Another cover member according to the present invention is a cover member that includes an outer wall surface and an inner wall surface and covers an opening in the image forming apparatus main body, and is arranged so as to face the inner wall surface without being in close contact therewith. A fixed portion for fixing at least one point on each of the vibration damping sheet, the inner wall surface, and one end side and the other end side in the first direction of the vibration damping sheet; and And a tension applying section that applies tension to the vibration damping sheet member when fixed. The image forming apparatus according to the present invention includes the cover member.

  The cover member manufacturing method according to the present invention is a method for manufacturing a cover member that includes an outer wall surface and an inner wall surface and covers an opening in the image forming apparatus main body, and is opposed to the inner wall surface in the image forming apparatus main body. A first step of fixing a damping sheet for damping vibration to the inner wall surface at a first position in a first direction; and a first step different from the first position in the first direction. And a second step of applying a tension to the vibration damping sheet.

  According to the present invention, it is possible to reduce radiated sound with a simple configuration without bringing a thin and light vibration damping sheet into close contact with the entire surface of the cover without a gap.

(A) is an external view of the cover member according to the present embodiment as viewed from the inside of the image forming apparatus main body, and (b) is a cover member with the vibration damping sheet (detailed later) removed. External view seen from the inside, (c) is an aa ′ sectional view. (A) is a cross-sectional view of a comparative example in which a vibration damping sheet is closely adhered and fixed as an evaluation panel for effect confirmation, and (b) is a cross section in an embodiment in which a vibration damping sheet is tensioned and fixed as an evaluation panel for effect confirmation. FIG. (A) is an external view of an image forming apparatus equipped with a cover member according to an embodiment of the present invention, and (b) is an external view of the image forming apparatus when the cover member is removed. 1 is a schematic configuration diagram of a drive unit in an image forming apparatus equipped with a cover member according to an embodiment of the present invention. It is an external appearance perspective view which shows the internal structure of a drive unit. It is an upper surface enlarged view which shows a part of drive transmission means of a drive unit. It is a graph which shows the effect of the exterior cover which has a vibration damping sheet concerning the embodiment of the present invention. It is an external view of the apparatus which confirms the effect of the exterior cover which has a damping sheet which concerns on embodiment of this invention. It is a graph which shows the effect in a 1st embodiment. (A) is the external view which looked at the cover member based on 2nd Embodiment from the inner wall surface side, (b) is a-a 'sectional drawing. It is a graph which shows the effect in 2nd Embodiment. (A), (b) is sectional drawing which shows a modification, respectively. 1 is a schematic cross-sectional view of an image forming apparatus equipped with a cover member according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<< First Embodiment >>
(Image forming device)
FIG. 13 is a schematic cross-sectional view showing a schematic configuration of an image forming apparatus equipped with a cover member according to an embodiment of the present invention. This image forming apparatus is a full-color laser printer that employs an inline method and an intermediate transfer method. This image forming apparatus can form a full-color image on a recording material 12 (for example, recording paper, plastic sheet, cloth, etc.) according to image information. The image information is input to the image forming apparatus main body from an image reading apparatus connected to the image forming apparatus main body 100 or a host device such as a personal computer connected to the image forming apparatus main body 100 in a communicable manner.

  The image forming apparatus main body 100 includes first, second, and second images for forming images of yellow (Y), magenta (M), cyan (C), and black (K), respectively, as a plurality of image forming units. 3 and a fourth image forming unit SY, SM, SC, SK. In the present embodiment, the configurations and operations of the first to fourth image forming units are substantially the same except that the colors of images to be formed are different. Therefore, in the following, unless there is a particular distinction, the subscripts Y, M, C, and K given to the reference numerals to indicate that they are elements provided for any color are omitted, and generally explain.

  The image forming apparatus main body 100 includes four drum-type electrophotographic photosensitive members, that is, the photosensitive drums 1 arranged in parallel in a direction crossing the vertical direction as a plurality of image carriers. Around the photosensitive drum 1, a charging roller 2 as a charging unit that uniformly charges the surface of the photosensitive drum 1, a laser is irradiated based on image information, and an electrostatic image (electrostatic latent image) is formed on the photosensitive drum 1. A scanner unit (exposure device) 3 is disposed as exposure means for forming (image).

  Further, around the photosensitive drum 1, a developing unit (developing device) 4 as developing means for developing an electrostatic image as a toner image, toner remaining on the surface of the photosensitive drum 1 after transfer (transfer residual toner) A cleaning member 6 that removes water is disposed. Further, an intermediate transfer belt 5 as an intermediate transfer body for transferring the toner image on the photosensitive drum 1 to the recording material 12 is disposed opposite to the four photosensitive drums 1.

  The photosensitive drum 1, and the charging roller 2, the developing unit 4, and the cleaning member 6 as process means acting on the photosensitive drum 1 are integrally formed into a cartridge to form a process cartridge 7. The process cartridges 7 for each color all have the same shape, and the toner for each color of yellow (Y), magenta (M), cyan (C), and blank (K) is contained in each color process cartridge 7. Is housed.

  An intermediate transfer belt 5 formed of an endless belt as an intermediate transfer member is in contact with all the photosensitive drums 1 and rotates. The intermediate transfer belt 5 is stretched around a driven roller 51, a secondary transfer counter roller 52, and a driving roller 53 as a plurality of support members. Then, four primary transfer rollers 8 as primary transfer means are arranged in parallel on the inner peripheral surface side of the intermediate transfer belt 5 so as to face the respective photosensitive drums 1.

  The primary transfer roller 8 presses the intermediate transfer belt 5 toward the photosensitive drum 1 to form a primary transfer portion N1 where the intermediate transfer belt 5 and the photosensitive drum 1 abut. A bias having a polarity opposite to the normal charging polarity of the toner is applied to the primary transfer roller 8 from a primary transfer bias power source (high voltage power source) as a primary transfer bias applying unit (not shown). As a result, the toner image on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 5.

  In addition, a secondary transfer roller 9 as a secondary transfer unit is disposed at a position facing the secondary transfer counter roller 52 on the outer peripheral surface side of the intermediate transfer belt 5. The secondary transfer roller 9 is in pressure contact with the secondary transfer counter roller 52 via the intermediate transfer belt 5 to form a secondary transfer portion N2 where the intermediate transfer belt 5 and the secondary transfer roller 9 are in contact with each other. A bias having a polarity opposite to the normal charging polarity of the toner is applied to the secondary transfer roller 9 from a secondary transfer bias power source (high voltage power source) as a secondary transfer bias applying unit (not shown). As a result, the toner image on the intermediate transfer belt 5 is transferred (secondary transfer) to the recording material 12.

  The recording material 12 onto which the toner image has been transferred is conveyed to a fixing device 10 as a fixing unit. The toner image is fixed on the recording material 12 by applying heat and pressure to the recording material 12 in the fixing device 10. Further, the primary transfer residual toner remaining on the photosensitive drum 1 after the primary transfer process is removed and collected by the cleaning member 6. The secondary transfer residual toner remaining on the intermediate transfer belt 5 after the secondary transfer process is cleaned by the intermediate transfer belt cleaning device 11.

  The image forming apparatus can form a single-color or multi-color image using only a desired single or some (not all) image forming units.

(Drive unit)
Next, the drive unit provided in the image forming apparatus main body 100 will be described with reference to FIG. FIG. 4 is a schematic configuration diagram of the drive unit 200. A drive unit 200 is installed on the back side of the rear plate 205 of the image forming apparatus main body 100. The driving unit 200 is fixed to the rear side plate 205 with screws through an attachment hole (not shown) of the driving side plate 201. FIG. 4 shows a configuration having three motors on the drive unit 200, which are an intermediate transfer belt rotation motor 202i, a color drum rotation motor 202d, and a color developing device rotation motor 202g, respectively.

  Each motor is mounted on a motor drive electrical board 204 that receives a power supply voltage and a drive signal supplied from a main body main unit (not shown) and converts them into a voltage signal directly applied to the motor. Further, the motor drive electrical board 204 is mounted on the drive support plate 203 to constitute a motor unit. In addition, the motor unit is configured such that the drive support plate 203 is fixed on the drive side plate 201 by means such as screws.

(Decelerator configuration as the internal configuration of the drive unit 200)
Next, the speed reducer configuration as the internal configuration of the drive unit 200 will be described with reference to FIG. In the drive unit 200, three mounted motors play different roles, and the details will be described below.

1) Intermediate Transfer Belt Rotation Motor As shown in FIG. 5, an intermediate transfer belt rotation motor pinion gear 303ip is attached to the tip of the motor shaft that rotates the intermediate transfer belt rotation motor 202i shown in FIG. In FIG. 5, the intermediate transfer belt rotation motor pinion gear 303ip performs drive distribution by a speed reducer and is first divided into two systems. In one system, the drive is first transmitted to the black developing device rotation first stage gear 301gk, and then transmitted to the black developing device rotation lower stage gear 302gk via the idler gear 310. A black developing device driving coupling 308k is attached to the black developing device rotating lower gear 302gk, and the driving force is transmitted to a developing device (not shown).

  As another type of drive distribution, power is transmitted from the intermediate transfer belt rotation motor pinion gear 303ip to the black drum rotation first stage gear 301dk. The black drum rotation first stage gear 301dk is further divided into two systems, one of which transmits power to the black drum rotation lower stage gear 302dk. A black drum driving coupling 309k is attached to the black drum rotating lower gear 302dk, and driving is transmitted to the black photosensitive drum through the coupling.

  Another system that is driven and distributed from the black drum rotation first gear 301dk rotates the intermediate transfer belt rotation lower gear 302i via an idler gear 310. The intermediate transfer belt rotation lower gear 302i rotates an intermediate transfer belt drive roller not shown in FIG.

  That is, in the present embodiment, the black developing device, the black photosensitive drum, and the intermediate transfer belt are rotated by one intermediate transfer belt rotation motor 202i (FIG. 4).

2) Color Drum Rotation Motor A color drum rotation motor pinion gear 303dp is attached to the tip of the rotating motor shaft of the color drum rotation motor 202d shown in FIG. 4 as shown in FIG. The color drum rotation motor pinion gear 303dp is first transmitted to the color drum rotation first stage gear 301d.

  In FIG. 5, the drive distribution is performed from the color drum rotation first gear 301d to the yellow drum rotation lower gear 302dy and the cyan drum rotation lower gear 302dc. Furthermore, drive transmission is made from the cyan drum rotation lower gear 302dc to the magenta drum rotation lower gear 302dm via an idler gear 310. Each drum rotation lower gear is provided with a drum drive coupling, and rotates a photosensitive drum of a color station (not shown).

3) Color Developer Rotation Motor A color developer rotation motor pinion gear 303gp is attached to the tip of the rotating motor shaft of the color developer rotation motor 202g shown in FIG. 4 as shown in FIG. In FIG. 5, the color developing unit rotation motor pinion gear 303gp is first transmitted to the color developing unit rotation first stage gear 301g. Then, the color developing unit rotation first stage gear 301g is driven and distributed to the magenta developing unit rotation lower stage gear 302gm and the cyan developing unit rotation lower stage gear 302gc.

  A drive is transmitted from the cyan developing device rotation lower gear 302gc to the yellow developing device rotation lower gear 302gy via an idler gear 310. A developing device drive coupling is attached to each developing device rotation lower gear, and the developing device of a color station (not shown) is rotated.

(Factors of noise generation in the drive unit)
Next, details regarding factors of noise generation in the drive unit will be described with reference to FIG. FIG. 6 is an enlarged view of the vicinity of the color developing device rotation motor 202g of the drive unit in FIG. 5 as viewed from above.

  In the image forming apparatus main body 100, when an image forming operation is started by a control command from a printer control unit (not shown), three motors installed on the drive unit 200 rotate. In this description, a case where the color developing device rotating motor 202g is rotated will be described as one representative example. The cause of noise generation in the basic drive unit is the same when the intermediate transfer belt rotation motor 202i and the color drum rotation motor 202d are rotated, and thus the description is omitted.

  In FIG. 6, when the color developing device rotating motor 202g rotates, the color developing device rotating motor pinion gear 303gp attached on the shaft of the color developing device rotating motor 202g also rotates simultaneously. The color developing device rotation motor pinion gear 303gp meshes with the color developing device rotation first stage large gear of the color developing device rotation first stage gear 301g, and is configured to reduce the rotation speed. Further, the color developing device rotation initial stage gear 301g of the color developing device rotation initial stage small gear meshes with the magenta developing device rotation lower stage gear 302gm and the cyan developing device rotation lower stage gear 302gc, thereby further reducing the speed.

  In the same manner as shown in FIG. 5, a developing device drive coupling is attached to each of the magenta developing device rotation lower gear 302gm and the cyan developing device rotation lower gear 302gc. Drive is transmitted from the developing device driving coupling to a developing device (not shown). Each gear is attached to a shaft fixed to the drive side plate 201 in a rotatable manner. For example, the color developing device rotation first stage gear 301g is attached to the color developing device first stage gear support shaft 306g, and the color developing device first stage gear support shaft 306g is fastened to the driving side plate 201 with screws or caulking.

  In FIG. 6, the color developing device rotation motor 202 g is attached to the drive support plate 203, and the drive support plate 203 is further attached to the drive side plate 201. In the driving unit 200 having such a configuration, when the color developing device rotation motor 202g is rotated to rotate the developing device, vibration radiation sound is generated from each part of the driving unit 200.

  Among them, the frame structure radiated sound radiated from the drive side plate 201 is a major factor. There are mainly the following two factors for the generation factor of the frame structure radiated sound. One is that the periodic vibration of the color developer rotating motor 202g itself is transmitted to the driving side plate 201 via the driving support plate 203, and becomes a frame structure radiation sound from the driving side plate 201. The other is that the meshing vibration between the color developing device rotation motor pinion gear 303gp and the color developing device first stage gear 301g is transmitted to the driving side plate 201 via the color developing device rotation motor 202g and the driving support plate 203, and driven. The frame structure radiates from the side plate.

(Vibration of cover member and cover member)
Next, an exterior cover 101 as a cover member according to this embodiment that covers the opening in the image forming apparatus main body 100 will be described with reference to FIGS. 1 and 3. 1A is an external view of the cover member according to the present embodiment as viewed from the inside of the image forming apparatus main body, and FIG. 1B is an image of the cover member with a vibration damping sheet (detailed later) removed. FIG. 1C is a cross-sectional view taken along the line aa ′, as viewed from the inside of the forming apparatus main body.

  3A is an external view of the image forming apparatus main body 100, and FIG. 3B is an external view of the image forming apparatus main body 100 provided with an opening when the exterior cover 101 is removed. As shown in FIG. 3, the exterior cover 101 of this embodiment is an exterior cover on the lower back side of the image forming apparatus main body 100. As shown in FIG. 1C, the exterior cover 101 includes an outer wall surface S <b> 1 and an inner wall surface S <b> 2, and when installed on the image forming apparatus main body 100, the exterior cover 101 is driven on the back side from the inner wall surface S <b> 2. It plays a role of insulating sound emitted from the unit 200.

  The exterior cover 101 of this embodiment shown in FIGS. 1A and 1C is manufactured by molding the base 101a and the rib 104 with a resin material, and the outer wall surface S1 and the inner wall surface S2 are substantially flat surfaces. It consists of Then, the air is exhausted from the inside of the image forming apparatus main body 100 or the opening 102 for taking in air from the outside of the image forming apparatus main body 100 or the main body frame of the image forming apparatus main body 100 is engaged (installed). Fastening portions (engagement portions) 103 and the like are provided. The rib 104 is provided inside the exterior cover 101 in order to ensure strength and prevent the occurrence of warpage.

  In general, the exterior cover 101 plays a role of insulating sound generated inside due to vibration of a vibration generation source (oscillator). However, there is no sufficient sound insulation, and it is transmitted to the outside due to the following factors. One is a leaking sound that leaks from the joint or opening between the outer covers 101, the other is a transmitted sound that passes through the outer cover, and the other is transmitted from the fastening portion. The vibration is an exterior radiated sound generated by vibrating the exterior cover 101.

  Among them, the transmitted sound and the exterior radiated sound are propagated to the outside when the exterior cover 101 vibrates. To reduce this, the vibration of the exterior cover may be reduced. Therefore, the exterior cover 101 in this embodiment includes a vibration damping sheet member (a vibration damping sheet) described below.

(Vibration control sheet)
In order to reduce the vibration of the outer cover 101 described above, the outer cover 101 is provided with a thin vibration damping sheet 111 having vibration damping characteristics in the present embodiment. In the present embodiment, a fixing portion 112a as a first fixing portion is provided on a part of the inner wall surface S2 without the rib 104, and a fixing portion 112b as a second fixing portion is provided at the tip of the rib 104. It has been. Thereby, in this embodiment, the damping sheet 111 is provided in the exterior cover 101 in a state where tension is applied. That is, in the present embodiment, the rib 104 functions as a tension applying unit.

  As the vibration damping sheet 111 of the present embodiment, a thickness of 300 μm of a vibration damping and shock absorbing sheet (AD-sorb SA645) made of styrene elastomer made by Karajan Co., Ltd. is used. However, the material and thickness are not limited to this, and a sheet having a thickness of about 30 μm to 400 μm formed by forming a vibration energy absorbing material having a loss factor of 0.05 or more by a mechanical impedance method into a thin film ( Vibration energy absorbing member). In order to produce a vibration damping effect, a sheet having a loss coefficient of 0.1 or more and a thickness of 100 μm or more is desirable.

  Here, regarding the fixing of the damping sheet 111 to the fixing portions 112a and 112b, in the present embodiment, the damping sheet 111 is provided with an adhesive layer. Then, after the damping sheet 111 is pulled and fixed to the fixing portion 112b of the rib 104 of the outer cover 101 by this adhesive layer, the damping sheet 111 is pushed in and a part of the inner wall surface without the rib 104 is pressed. The fixing part 112a was fixed.

  In addition, when the adhesive layer is not provided in the damping sheet 111, you may apply | coat an adhesive material to the fixing | fixed part 112a, 112b previously. That is, the damping sheet 111 may be fixed after an adhesive is applied in advance to the fixing part 112b at the tip of the rib 104 and a part of the fixing part 112a of the inner wall surface S2 without the rib 104.

  The method for fixing the vibration damping sheet 111 to the fixing portion is not limited to the above-described method, and for example, the vibration damping sheet 111 may be fixed to the exterior cover 101 using a vacuum forming method. Alternatively, the vibration damping sheet 111 may be melted by heat and fixed using a welding layer or a double-sided tape that is welded by pressurization or cooling. In addition, you may fix using mechanical joining by a rivet, a screw, etc.

  The fixing unit 112b only needs to be able to hold the damping sheet 111 with tension. Therefore, it is only necessary to be provided on at least the two ribs 104 facing the upper and lower sides of the outer cover 101 or the two ribs 104 facing the left and right sides of the outer cover 101.

(Effect of exterior cover with vibration damping sheet)
Next, the effect of the exterior cover 110a provided with the vibration damping sheet in this embodiment will be described. FIG. 2A is a cross-sectional view of a comparative example in which the vibration damping sheet is closely attached and fixed as an evaluation panel for effect confirmation, and FIG. 2B is a vibration damping sheet fixed and tensioned as an evaluation panel for effect confirmation. It is sectional drawing in embodiment.

  Here, a vibrator was attached to the drive side plate 201 (FIG. 4) of the drive unit 200 (FIG. 3B), and the vibration state of the exterior cover 101 was measured when random excitation was performed at 50 Hz to 5 kHz. For vibration measurement, a PU probe manufactured by Microflow Technologies was used, and the acoustic particle velocity (PVL) in the vicinity of the surface (outer wall surface S1) of the exterior cover 101 was measured without contact.

  As a result, as shown in FIG. 7, the acoustic particle velocity of the exterior cover 110 a having the vibration damping sheet 111 of this embodiment decreased from 200 Hz onward with respect to the exterior cover 101 (Ref). That is, the vibration is reduced, and the effect of the configuration of this embodiment has been confirmed.

  Next, the evaluation panel shown in FIG. 2 is installed in the examination apparatus shown in FIG. 8, and the difference in the arrangement configuration of the vibration damping sheets of the comparative example (FIG. 2A) and the present embodiment (FIG. 2B) is shown. We confirmed the difference in effect. The examination apparatus shown in FIG. 8 is an acoustic box 400 having a side of 300 mm, and the acoustic box 400 includes an ABS evaluation panel 401 having a thickness of 2 mm and an iron panel 402 having a thickness of 4 mm.

  The panel 402 on the opposite surface of the evaluation panel 401 has an opening (not shown) into which the tube of the acoustic vibrator 403 can be inserted. The tube of the acoustic vibrator 403 is inserted into the opening of the panel 402 and fixed. Thus, the inside of the acoustic box 400 can be acoustically excited.

  The evaluation panel shown in FIG. 2 (corresponding to reference numeral 401 in FIG. 8) is made of ABS with a side of 300 mm and a thickness of 2 mm, and a damping sheet 111 is provided on a surface provided with ribs having a height of 10 mm in a grid with intervals of 50 mm. It is fixed. FIG. 2A shows a panel (full contact panel) in which a damping sheet member having a thickness of 300 μm used in the present embodiment is closely attached and fixed along the ribs as a comparative example. On the other hand, FIG. 2B shows a panel (tension applying panel) in which a vibration damping sheet 111 applied with tension is bonded and fixed to a rib tip and a surface 10 mm × 10 mm having no rib simulating the configuration of the present embodiment.

  And in FIG. 8, when each evaluation panel shown with the code | symbol 401 is installed so that the fixed surface of the damping sheet 111 may become the inner side of the acoustic box 400, when it randomly vibrates at 50 Hz-5 kHz with the acoustic vibrator 403 The result of measuring the vibration state of the surface of the evaluation panel is shown in FIG. For the vibration measurement, a laser Doppler vibrometer (LDV) manufactured by Polytec was used. As shown in FIG. 9, the vibration level of the tension applying panel (FIG. 2B) that simulates the configuration of the present embodiment is equal to or higher than that of the full adhesion panel (FIG. 2A). It was confirmed that In particular, a reduction in vibration level was confirmed at a peak after 1 kHz (1000 Hz).

  From the above, rather than closely adhering the vibration damping sheet to the entire panel surface, the tension is applied to the rib tip and a part of the inner wall surface (S2) without the rib as in the configuration of the present embodiment. It turned out that it is effective to provide. That is, it has been found that it is effective to provide the vibration damping sheet so as to face the fixed portion of the inner wall surface without closely contacting the entire surface.

  This is considered to be due to the fact that when the exterior cover 101 vibrates, the distortion is greater than the state in which the damping sheet is in close contact with the entire panel surface, and vibration energy is efficiently converted into thermal energy. Therefore, in the configuration of the present embodiment, the vibration of the exterior cover can be reduced with a small number of damping sheets.

<< Second Embodiment >>
Next, a second embodiment of the present invention using a damping net member as a damping sheet will be described with reference to FIG. In the present embodiment, only points different from the first embodiment will be described, and the description of the same configuration as the first embodiment will be omitted. FIG. 10A is an external view of an exterior cover 101 ′ having a vibration damping net member according to this embodiment, and FIG. 10B is a cross-sectional view taken along the line aa ′ in FIG.

  In this embodiment, the damping net member 113 in which the damping member has a mesh shape is used. Note that the damping net member 113 is not limited to a mesh shape, as long as the damping net member 113 has an opening rather than a sheet shape on one side.

  As in the first embodiment, the vibration damping net member 113 of the present embodiment has a vibration-damping and shock-absorbing sheet (AD-sorb SA645) thickness of 300 μm made of styrene elastomer made by Karajan as a mesh. The vibration-damping net member machined into However, the material and thickness are not limited to this, and a net having a thickness of about 30 μm to 400 μm obtained by molding a vibration energy absorbing material having a loss factor of 0.05 or more by the mechanical impedance method may be used. In order to obtain a more effective damping effect, a net having a thickness of 100 μm or more with a loss coefficient of 0.1 or more is desirable.

  The damping net member 113 is provided with an adhesive layer. Then, after tension is applied to the fixing portion 112b of the rib 104 of the exterior cover 101 ′ while pulling and fixing the damping net member 113, the damping net member 113 is pushed in, and a part of the inner wall surface S2 without the rib 104 is inserted. The fixing part 112a was fixed.

  In addition, when the adhesive layer is not provided in the damping net member 113, you may apply | coat an adhesive material to the fixing | fixed part 112a, 112b previously. In other words, the damping net member 113 may be fixed after an adhesive is applied in advance to the fixing part 112b at the tip of the rib 104 and a part of the fixing part 112a of the inner wall surface S2 without the rib 104.

  The method of fixing the damping net member 113 to the fixing portion is not limited to the above-described method, and the damping net member 113 may be fixed to the exterior cover 101 ′ using, for example, a vacuum forming method. Alternatively, the damping net member 113 may be fixed by using a welded layer that is melted by heat and welded by pressurization or cooling, or a double-sided tape. In addition, you may fix using mechanical joining by a rivet, a screw, etc.

  The fixing portion 112b only needs to be able to hold the damping net member 113 by applying tension. Therefore, it is only necessary to be provided on at least the two ribs 104 on the upper and lower sides of the outer cover 101 'facing each other or the two ribs 104 on the left and right sides of the outer cover 101' facing each other.

(Effect of exterior cover with damping net member)
Next, the effect of the exterior cover 101 ′ having the vibration damping net member of this embodiment will be described. As in the first embodiment, the vibration state of the exterior cover 101 when a vibrator is attached to the drive side plate 201 (FIG. 4) of the drive unit 200 (FIG. 3B) and randomly vibrated at 50 Hz to 5 kHz. Was measured. For vibration measurement, a PU probe manufactured by Microflow Technologies was used, and the acoustic particle velocity (PVL) in the vicinity of the surface (outer wall surface S1) of the exterior cover 101 was measured without contact.

  As a result, as shown in FIG. 11, the acoustic particle velocity of the exterior cover 101 ′ having the vibration damping sheet 111 according to the present embodiment decreased from 200 Hz onward with respect to the exterior cover (Ref). That is, the vibration is reduced, and the effect of the configuration of this embodiment has been confirmed.

  As described above, it is also effective to provide a damping member having a mesh shape with an opening instead of a sheet-like surface with tension applied to the rib tip and a part of the surface without the rib as in the configuration of this embodiment. I found out. Similar to the first embodiment, it is considered that the distortion of the damping net member increases when the exterior cover 101 ′ vibrates, and vibration energy is efficiently converted into thermal energy. Therefore, in the configuration of the present embodiment, the vibration of the exterior cover can be reduced with a smaller number of damping members.

(Manufacturing method of cover member)
The manufacturing method of the cover member mentioned above is demonstrated below. A method for manufacturing a cover member according to an embodiment of the present invention is a method for manufacturing a cover member that includes an outer wall surface and an inner wall surface and covers an opening in an image forming apparatus main body, and includes a first step and a second step. . In the first step, a damping sheet that opposes the inner wall surface and suppresses vibration in the image forming apparatus main body is fixed to the inner wall surface at a first position in the first direction. In the second step, the vibration damping sheet is fixed at a second position different from the first position in the first direction and tension is applied to the vibration damping sheet.

  Furthermore, in the second step, tension is applied through a plurality of ribs that protrude from the inner wall surface and are provided in the first direction. Or in a 2nd process, tension | tensile_strength is provided via the rib provided in the 2nd direction which protrudes from an inner wall face and orthogonally crosses a 1st direction and a 1st direction.

(Modification)
As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

(Modification 1)
In the embodiment described above, the vibration damping sheet provided in the cover member is fixed to the inner wall surface at the first position in the first direction by the fixing portion 112a, and is adjacent (closest) at the second position in the first direction. It was fixed by the fixing part 112b of the rib. However, the present invention is not limited to this, and may be configured as shown in FIG. That is, the vibration damping sheet provided in the cover member is fixed to the inner wall surface by the fixing portion 112a at the first position in the first direction, and the ribs separated from the closest relation rib at the second position in the first direction are You may fix with the fixing | fixed part 112b.

  Thus, what is necessary is just to fix at least one point or more on each of the inner wall surface and the one end side and the other end side in the first direction of the vibration damping sheet.

  Further, in the above-described embodiment, the vibration damping sheet provided in the cover member is fixed to the inner wall surface with the fixing portion 112a at the first position in the first direction, and the rib fixing portion at the second position in the first direction. Although it fixed by 112b, this invention is not limited to this. As shown in FIG. 12B, the fixing portion 112a may fix the inner wall surface at the first position and the second position.

(Modification 2)
In the above-described embodiment, the plurality of ribs are provided two-dimensionally in the first direction and in the second direction orthogonal to the first direction, but may be provided one-dimensionally.

101, 101 '... Cover member, 111, 113 ... Damping sheet, 112a, 112b ... Fixing part, 104 ... Rib (tension applying part), S1 ... Outer wall surface, S2 ... Inner wall surface

Claims (12)

A cover member that includes an outer wall surface and an inner wall surface and covers an opening in the image forming apparatus main body,
A damping sheet that opposes the inner wall surface and suppresses vibration in the image forming apparatus main body;
A fixing portion for fixing the vibration damping sheet to the inner wall surface at a first position in a first direction;
The vibration damping sheet is fixed at a second position different from the first position in the first direction, and tension is applied to the vibration damping sheet without closely contacting the vibration damping sheet to the inner wall surface. A tensioning section;
The cover member characterized by having.   The cover member according to claim 1, wherein the tension applying portion includes a rib protruding from the inner wall surface.   The cover member according to claim 2, wherein the second position is a position of the rib.   The cover member according to claim 2, wherein the second position is a position of the inner wall surface via the rib.   5. The cover member according to claim 2, wherein a plurality of the ribs are provided in the first direction, and the first position is a position sandwiched between the plurality of the ribs.   The plurality of ribs are provided in the first direction and a second direction orthogonal to the first direction, and the first position is a plurality of the ribs in the first direction and the second direction. The cover member according to any one of claims 2 to 4, wherein the cover member is located between the two.   The cover member according to any one of claims 1 to 6, wherein the vibration damping sheet is a vibration energy absorbing member having a loss factor of 0.05 or more by a mechanical impedance method. A cover member that includes an outer wall surface and an inner wall surface and covers an opening in the image forming apparatus main body,
A damping sheet arranged to face the inner wall without being in close contact with the inner wall;
A fixing portion that fixes at least one point on each of the inner wall surface and one end side and the other end side in the first direction of the vibration damping sheet;
A tension applying portion that applies tension to the vibration damping sheet member when the vibration damping sheet is fixed by the fixing portion;
The cover member characterized by having.   An image forming apparatus comprising: an image forming apparatus main body; and the cover member according to claim 1. A method of manufacturing a cover member that includes an outer wall surface and an inner wall surface and covers an opening in an image forming apparatus main body,
A first step of fixing a vibration damping sheet facing the inner wall surface and suppressing vibrations in the image forming apparatus main body to the inner wall surface at a first position in a first direction;
A second step of fixing the vibration damping sheet at a second position different from the first position in the first direction and applying tension to the vibration damping sheet;
The manufacturing method of the cover member characterized by having.   11. The method for manufacturing a cover member according to claim 10, wherein in the second step, tension is applied through a plurality of ribs that protrude from the inner wall surface and are provided in the first direction.   The tension in the second step is applied through a plurality of ribs that protrude from the inner wall surface and are provided in the first direction and a second direction orthogonal to the first direction. The manufacturing method of the cover member of description.