JP2015215547A - Optical scanner and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid an increase of noise due to a whistle-like noise generated at the entries of respective resonance paths (125c) of five Helmholtz resonators (141 to 145) and avoid an increase in cost due to provision of a new Helmholtz resonator to reduce a whistle-like noise.SOLUTION: Five Helmholtz resonators are disposed while the entries of resonance paths 125c are directed to a polygon mirror 48, and a folding mirror 126 is interposed between the polygon mirror 48 and the entries of the respective resonance paths (125c) of the five Helmholtz resonators (141 to 145). An air current generated by the rotating polygon mirror 48 and advanced to the Helmholtz resonators is caused to hit the folding mirror 126 before the entries of the resonance paths (125c), so as to prevent the air current from directly entering the entries.

Description

  The present invention relates to an optical scanning device having a deflecting unit that deflects the traveling direction of light emitted from a light source by a deflecting mirror driven by a driving source, and an image forming apparatus equipped with the same.

  Conventionally, as this type of optical scanning device, the one described in Patent Document 1 is known. This optical scanning device deflects the traveling direction of laser light emitted from a laser light source by a rotating polygon mirror as a deflecting mirror rotated by a motor as a driving source. In such a configuration, wind noise caused by the edge of the mirror surface of the rotating rotary polygon mirror becomes noise. Also, the sound generated by the motor as it is driven becomes noise. In order to reduce such noise, in the optical scanning device described in Patent Document 1, a resonator that resonates at a resonance frequency suitable for the noise is integrally provided in the housing of the optical scanning device. And noise can be reduced by attenuating noise by resonance by this resonator.

  However, in this optical scanning device, there is a possibility that new noise may be generated when a layout in which the resonator is disposed in the surrounding area surrounding the polygonal mirror of the rotary polygonal mirror is adopted due to layout restrictions or the like. is there. Specifically, in this optical scanning device, the rotary polygon mirror connected to the motor is positioned on the other surface side of the support plate having the motor fixed to one surface. The rotating polygon mirror generates an air flow as it rotates, and a support plate with a motor fixed is interposed between the air flow and the resonance path of the resonator. For this reason, the airflow generated with the rotation of the rotary polygon mirror does not directly reach the entrance of the resonance passage. However, due to layout constraints, if a resonator is installed in the surrounding area surrounding the polygon mirror of the rotary polygon mirror, the air flow generated by the rotation of the rotary polygon mirror directly reaches the entrance of the resonance path of the resonator. Therefore, there is a risk of generating a new noise such as a whistle (hereinafter referred to as a whistle-like noise). In order to reduce the whistle-like noise, if a new resonator having a resonance frequency suitable for the whistle-like noise is newly installed, the cost increases.

  In addition, although the problem that occurs when the resonator is disposed in the surrounding area surrounding the polygonal mirror of the rotating polygonal mirror has been described, when using a deflecting mirror that performs not only rotation but also a swinging operation, A similar problem may occur in the layout in which the resonator is disposed in the specular projection region of the deflecting mirror.

  The present invention has been made in view of the above background, and an object thereof is to provide the following optical scanning device and an image forming apparatus including the same. In other words, with the layout in which the resonator is positioned within the specular projection area of the deflecting mirror, the cost is increased by newly providing a resonator to reduce the whistle-like noise while suppressing the increase in noise due to the whistle-like noise. This is an optical scanning device or the like that can avoid the above.

  In order to achieve the above object, the present invention provides a deflecting means for deflecting a traveling direction of light emitted from a light source by a deflecting mirror driven by a driving source, and a resonance space for reducing noise emitted from the deflecting means. And an optical scanning device comprising: a resonator including a resonance path communicating with the resonance space for guiding noise from outside the resonance space; and a housing containing at least the deflection unit and the reflection member. The resonance path is arranged such that an optical system component different from the deflecting mirror is interposed between the mirror surface of the deflecting mirror and the entrance, while the entrance of the resonance path is located in the specular projection region of the deflecting mirror. A device is provided.

  According to the present invention, in the layout in which the resonator is positioned in the specular projection region of the deflecting mirror, a resonator for reducing the whistle-like noise is newly provided while suppressing the increase in noise due to the whistle-like noise. The cost increase due to can be avoided.

1 is a schematic configuration diagram showing a copier according to an embodiment. 6 is a graph showing measurement results of noise generated when the polygon motor or polygon mirror of the copier is rotated at a speed of 34000 rpm. FIG. 2 is a plan view showing an optical scanning device of the copier. The disassembled top view which shows the same optical scanning device of the state which removed the cover member. The perspective view which shows the fracture | rupture part of the optical scanning device fractured | ruptured in the position of the A-A 'fracture line of FIG. The front view which shows the same fracture | rupture part. The top view which shows the same fracture | rupture part of the state which removed the cover member. The perspective view which shows the same fracture | rupture part from the side. FIG. 2 is a partially exploded perspective view showing a part of the copier. The partial exploded perspective view which shows the same part from another direction.

  Hereinafter, an embodiment of a copying machine 500 will be described as an example of an image forming apparatus to which the present invention is applied. The copying machine 500 according to the embodiment forms only a monochrome image, but the present invention can also be applied to an image forming apparatus that forms a multicolor image such as a full color image.

First, a basic configuration of the copier 500 according to the embodiment will be described.
FIG. 1 is a schematic configuration diagram illustrating a copying machine 500 according to the embodiment. The copier 500 includes a printer unit 100, an image reading device 200, a recording sheet bank 300, an automatic document feeder 400, and the like. The printer unit 100 is mounted directly above the recording sheet bank 300, and the image reading device 200 is fixed directly above the printer unit 100. An automatic document feeder 400 is attached directly above the image reading apparatus 200, and is rotated by using a hinge provided on the back side (back side in the direction orthogonal to the paper surface in the drawing) as a fulcrum. Then, the contact glass of the image reading apparatus 200 is opened and closed.

  Inside the printer unit 100, a drum-shaped photosensitive member 10, a charging device 11, a developing device 12, a transfer unit 13, a cleaning device 14, a toner replenishing device 20, a fixing device 22 and the like are provided as latent image carriers. . Around the photoreceptor 10 on which the toner image is formed, a charging device 11, a developing device 12, a transfer unit 13, a cleaning device 14, and the like including a charging roller are disposed. Among these, the photoconductor 10, the charging device 11, the developing device 12, and the cleaning device 14 are configured as a process cartridge that is integrally attached to and detached from the printer unit 100 while being held by a common holding body. .

  The developing device 12 develops an electrostatic latent image on the photosensitive member 10 using toner carried on the surface of a developing roller as a developer carrying member, and forms a toner image on the surface of the photosensitive member 10. is there. The transfer unit 13 includes a transfer downstream roller 15, a transfer upstream roller 16, and a transfer belt 17 that is stretched around these two rollers and moves endlessly in the clockwise direction in the drawing. have. The transfer belt 17 contacts the peripheral surface of the photoconductor 10 at the transfer position B to form a transfer nip.

  On the left side of the charging device 11 and the cleaning device 14 in the figure, a toner supply device 20 for supplying new toner to the developing device 12 is provided. Further, a recording sheet conveying device 60 that conveys the recording sheet P sent from the recording sheet cassette 61 of the recording sheet bank 300 from the lower side to the upper side in the vertical direction is provided at the right end of the printer unit 100 in the drawing. ing. The recording sheet conveying apparatus 60 passes the recording sheet P that has passed through the sheet feeding path R1 and the sheet feeding path R2 along the recording sheet conveying path R through the transfer position B and the recording sheet conveying path R, and then the stack unit 39. Transport to. A registration roller pair 21 is provided upstream of the transfer position B in the recording sheet conveyance path R in the conveyance direction. A fixing device 22 is provided downstream of the transfer position B in the transport direction.

  The fixing device 22 forms a fixing nip by bringing a heating roller 30 as a heating member into contact with a pressure roller 32 as a pressure member, and heats and presses the recording sheet P sandwiched between the fixing nips. Thus, the toner image is fixed on the surface of the recording sheet P. A discharge branch claw 34, a discharge roller 35, a first pressure roller 36, a second pressure roller 37, and a roller 38 with stiffness are disposed downstream of the fixing device 22 in the recording sheet conveyance direction. A stack unit 39 is also provided for stacking the recording sheets P that have undergone image fixing through the fixing device 22.

  An optical scanning device 47 is disposed on the left side of the developing device 12 in the drawing. This optical scanning device 47 has a polygon scanner 120 as a deflecting means having a polygon mirror 48 as a deflecting mirror and a polygon motor 49 as a driving source. Further, a scanning optical system such as a laser light source (not shown) is also provided. A switchback device 42 is provided on the right side of the printer unit 100 in the drawing. The switchback device 42 re-directs the recording sheet P to the position of the registration roller pair 21 in the recording sheet conveyance path R and the reversing path R3 branched from the position where the discharge branch claw 34 of the recording sheet conveyance path R is disposed. The recording sheet P is conveyed along the conveyance path R4. In the reversing path R3 and the re-conveyance path R4, a pair of switchback roller pairs 43, a plurality of other recording sheet conveyance roller pairs 66, and the like are disposed.

  The image reading apparatus 200 includes a reading light source 53, a plurality of mirrors 54, an imaging optical lens 55, an image sensor 56 including a CCD, and the like, and a contact glass 57 is provided on the upper surface thereof. The automatic document feeder 400 is provided with a document setting table (not shown) and a document stacking table (not shown) as a document discharge position. The automatic document conveying device 400 includes a plurality of document conveying rollers, and the document conveying rollers convey the document from the document setting table to the document stacking table via the reading position on the contact glass 57 of the image reading device 200. To do.

  Inside the recording sheet bank 300, a plurality of recording sheet cassettes 61 for storing recording sheets P such as recording paper and OHP film are provided in an overlapping manner. Each recording sheet cassette 61 is provided with a call roller 62, a paper feed roller 63, and a separation roller 64.

  On the right side of the recording sheet cassette 61 in the figure, the above-described sheet feeding path R1 leading to the recording sheet conveyance path R of the printer unit 100 is formed. Also in this paper feed path R1, several recording sheet conveying roller pairs 66 for conveying the recording sheet P are provided. A manual paper feed unit 68 is provided on the right side of the recording sheet bank 300 in the drawing. The manual paper feed unit 68 is provided with a manual tray 67 that can be opened and closed. The manual paper feed path R2 that guides the manual recording sheet P set on the manual feed tray 67 to the recording sheet conveyance path R. Is formed. Similarly to the recording sheet cassette 61, the manual paper feed unit 68 is also provided with a calling roller 62, a paper feed roller 63, and a separation roller 64.

  When copying using the copying machine 500, first, a main switch (not shown) is turned on. If the document is not bound, the document is set on the document setting table of the automatic document feeder 400. In the case of a single-bound document such as a book document, the automatic document feeder 400 is opened and a document is set on the contact glass 57 of the image reading device 200, and then the automatic document feeder 400 is closed to contact the document. Press against glass 57. When a start switch (not shown) is pressed, the document set on the automatic document feeder 400 passes over the contact glass 57 in the process of being conveyed in the document conveyance path by the document conveyance roller of the automatic document feeder 400. At this time, after the image of the document is read by the image reading device 200, the document is discharged onto the document stacking table of the automatic document feeder 400. On the other hand, the original image is read by driving the image reading apparatus 200 on the one-sided original pressed against the contact glass 57. At this time, the image reading apparatus 200 irradiates the original surface on the contact glass 57 with light from the reading light source 53 while moving the reading light source 53 along the contact glass 57. Then, the reflected light is guided to the imaging optical lens 55 by a plurality of mirrors 54 and put into the image sensor 56, and the document image is read by the image sensor 56.

  When the reading of the document image is started, the printer unit 100 drives a photoconductor drive motor (not shown) to rotate the photoconductor 10 in the counterclockwise direction in the drawing. Then, while the charging device 11 uniformly charges the surface of the photoconductor 10, the optical scanning device 47 performs optical scanning on the charged surface of the photoconductor 10. By this optical scanning, the region irradiated with the laser light L on the surface of the photoconductor 10 becomes an electrostatic latent image by attenuating the potential. The electrostatic latent image becomes a toner image when the developing device 12 attaches the toner to the visible image.

  On the other hand, triggered by the pressing of the above-mentioned start switch, the recording sheet P that is selected in advance by the user among the plurality of recording sheet cassettes 61 in the recording sheet bank 300 is sent out by the calling roller 62. The fed recording sheet P is separated into one sheet when passing through the separation nip formed by the contact between the sheet feeding roller 63 and the separation roller 64, and after one sheet is guided to the sheet feeding path R1, the recording sheet is separated. The sheet is guided to the recording sheet conveyance path R by the conveyance roller pair 66. After that, it comes into contact with the registration roller pair 21 and is stopped. When the user selects the manual paper feed unit 68, the user sets the recording sheet P on the expanded manual feed tray 67. In this case, after the recording sheet P is sent out by the calling roller 62, it is separated into one sheet by the paper feed roller 63 and the separation roller 64 and is conveyed to the manual paper feed path R2. Thereafter, after being guided to the recording sheet conveyance path R by the recording sheet conveyance roller pair 66, the recording sheet conveyance roller pair abuts against the registration roller pair 21 and is stopped.

  In this way, the recording sheet P that has struck the registration roller pair 21 is transferred to the transfer nip (transfer position B) by the registration roller pair 21 at a timing synchronized with the toner image on the surface of the photoreceptor 10 at the transfer nip described above. It is sent. Then, after the toner image on the photoconductor 10 is transferred by the transfer unit 13, it is discharged from the transfer nip.

  Transfer residual toner adheres to the surface of the photoreceptor 10 that has passed through the transfer nip. This transfer residual toner is removed from the surface of the photoreceptor 10 by the cleaning device 14. The surface of the photoreceptor 10 after the cleaning is charged by a charging lamp 11 after being neutralized by a neutralizing lamp (not shown).

  The recording sheet P that has passed through the transfer nip is conveyed by the transfer belt 17 and sent to the fixing device 22. Then, in the fixing device 22, the toner image is fixed on the surface of the fixing device 22 while being sandwiched in a fixing nip formed by contact between the heating roller 30 and the pressure roller 32 and being heated and pressed.

  The recording sheet P on which the toner image is fixed in this manner is discharged from the fixing device 22 and then sequentially passes through the discharge roller 35, the first pressure roller 36, the second pressure roller 37, and the stiffness roller 38. After that, it is discharged onto the stack unit 39 and stacked there.

  When the double-sided printing mode for forming images on both sides of the recording sheet P is selected, the recording sheet P having the toner image fixed on only one side exits the fixing device 22 and is then reversed by the discharge branch claw 34. Guided to R3. Then, after entering the switchback position 44 by the recording sheet conveying roller pair 66, the recording sheet conveying roller pair 66 is switched back by the switchback roller pair 43, and this time is guided to the reconveying path R <b> 4. Thereafter, after being guided again to the recording sheet conveyance path R by the recording sheet conveyance roller pair 66, the toner image is transferred to the other surface through the registration roller pair 21 at the transfer nip. Thereafter, it is discharged onto the stack unit 39 in the same manner as in the single-sided print mode.

  In the optical scanning device 47, noise having a peak at a specific frequency depending on the rotation period is generated from the polygon scanner 120 that rotationally drives the polygon motor 49 and the polygon mirror 48. FIG. 2 is a graph showing measurement results of noise generated when the polygon motor 49 and the hexahedral polygon mirror 48 are rotated at a speed of 34000 rpm. As shown in the drawing, the noise generated from the polygon scanner 120 includes the sound of one rotation component (rotation frequency) (sliding sound) of the polygon mirror 48 and the sound of one surface component (one surface frequency) of the polygon mirror 48 (wind cutting). Sound). These sounds propagate through the air inside the optical scanning device 47 and then propagate to the casing of the optical scanning device 47, and then propagate to the air outside the optical scanning device 47 and are recognized as noise. Under the condition of 34000 rpm, noise of one rotation component is generated as sound having a frequency of 566 [Hz], and noise of one surface component is generated as sound having a frequency of 3400 [Hz].

  As a countermeasure against these noises, a method of confining noise in the sealed space by confining the accommodation space of the polygon scanner 120 in the space inside the optical scanning device 47 as a sealed space from other spaces can be considered. . However, in this method, the heat generated from the polygon motor 49 may cause the temperature in the sealed space to rise excessively, causing various problems due to overheating.

  Further, as another noise countermeasure method, a method of making the entire interior of the optical scanning device 47 a sealed space is conceivable. However, with this method, a good sealing effect cannot be obtained, and a lot of noise emitted from the polygon scanner 120 may be leaked outside the optical scanning device 47.

  Therefore, in the copying machine 500 according to the embodiment, a Helmholtz sound absorber as a resonator is provided in the optical scanning device 47, and the resonance of the Helmholtz sound absorber causes the noise of the mirror 1 rotation component and the mirror 1 surface component. Noise is reduced.

The Helmholtz sound absorber includes a resonance space having an internal volume (V), a resonance path having a length (L) for communicating the resonance space with an external space, and a cross-sectional area (S). The resonance frequency f of this Helmholtz sound absorber is expressed by the equation “f = (c / 2π) · (S / V · (L + δ)) ^1/2 ”. V is the internal volume of the resonance space, L is the length of the resonance path, S is the cross-sectional area of the resonance path, c is the speed of sound, and δ is the open end correction value. The opening end correction value δ is for correcting the influence of resonance in the vicinity of the entrance of the resonance path, and generally around 0.5 to 1.2 is used.

  However, when such a Helmholtz sound absorber is provided, the air flow generated by the rotation of the polygon mirror 48 hits the entrance of the resonance path of the Helmholtz sound absorber, thereby generating a whistle-like noise such as a whistle sound. There was a risk of letting it go. If a Helmholtz sound absorber having the same resonance frequency as that of the whistle-like noise is newly installed in order to reduce the whistle-like noise, the cost increases.

Next, a characteristic configuration of the copier 500 according to the embodiment will be described.
FIG. 3 is an exploded perspective view showing the optical scanning device 47 from the bottom side. The optical scanning device 47 shown in the figure is set in the copier 500 with the posture turned upside down from the state shown in the figure. The optical scanning device 47 houses an optical system such as a polygon scanner 120 and a scanning lens 128 having both an fθ correction function and a surface tilt correction function in a housing 125. The casing 125 includes a main body 125b having a maintenance inspection opening facing downward in the vertical direction, and a bottom lid member 125a for closing the opening of the main body 125b. The polygon scanner 120 includes a regular hexahedron polygon mirror 48 and a polygon motor for rotationally driving the polygon mirror 48, but the polygon motor is hidden behind the polygon mirror 48 and cannot be seen in FIG. The bottom cover member 125a is fixed to the main body 125b, thereby covering the opening of the main body 125b.

  In the figure, the resonator unit 130 is located in the specular projection region of the polygon mirror 48. The specular projection area is an area extending from the entire mirror surface in a direction perpendicular to the mirror surface. Unlike an actual shadow, even if some member exists in the middle, it extends through it. It is. When the mirror surface is a curved surface, the region extends from the entire surface of the curved surface in the normal direction. Further, since the deflecting mirror according to the present invention operates, the deflecting mirror is a region extending from the mirror surface in any posture that can be taken by the operation. In the case of a regular hexagonal mirror, the surrounding area surrounding the regular hexagonal mirror around the rotation axis is the specular projection area.

  In FIG. 1, the right side in the drawing is the right side of the copying machine main body and the left side in the drawing is the left side of the copying machine main body. Further, the front side in the direction orthogonal to the drawing sheet is the front side of the copying machine main body, and the back side in the same direction is the rear side of the copying machine main body. On the other hand, in FIG. 3, the downstream side in the arrow y direction is the right side of the copying machine body, the upstream side in the arrow y direction is the left side of the copying machine body, the downstream side in the arrow x direction is the rear side of the copying machine body, The upstream side in the x direction is the front side of the copying machine main body. Further, the downstream side in the arrow z direction is the lower side of the copier body, and the upstream side in the arrow z direction is the upper side of the copier body. That is, in FIG. 3, the right and left are reversed and the top and bottom are reversed with respect to the actual posture of the optical scanning device 47. The optical scanning device 47 is set on the copying machine main body in a posture rotated clockwise by about 90 ° C. from the posture shown in the drawing.

  In FIG. 3, the optical scanning device 47 includes a resonator unit 130. The right side wall (left side wall in the figure) of the main body 125b of the casing 125 also serves as the left side wall (right side wall in the figure in the unit) of the resonator unit 130. A resonance unit cover 131 including three side walls and a ceiling wall excluding the left side wall in the resonator unit 130 is fixed to the right side wall of the main body 125b from the outside by screws, double-sided tape, or the like. It may be fixed by welding or adhesion. The bottom lid member 125a also serves as the bottom wall of the resonator unit 130. In a state where the bottom cover member 125a is removed from the main body 125a, the opening of the main body 125b is exposed, and the respective resonance spaces in the five Helmholtz resonators described later of the resonance unit cover 131 are also exposed to the outside.

  The resonator unit 130 includes a first Helmholtz resonator 141, a second Helmholtz resonator 142, a third Helmholtz resonator 143, a fourth Helmholtz resonator 144, and a fifth Helmholtz resonator 145 arranged in the front-rear direction of the copying machine main body. It has. The first Helmholtz resonator 141 is located on the most rear side with respect to the copying machine main body, and the fifth Helmholtz resonator 145 is located on the most front side. Five through holes 125c functioning as respective resonance paths in the five Helmholtz resonators 145 are formed on the right side wall of the main body 125b so as to be aligned in the front-rear direction of the copying machine main body. Each of the five Helmholtz resonators has a resonance space, and these resonance spaces communicate with the internal space of the housing 125 through the above-described through hole (resonance passage) 125c. Noise generated from the polygon scanner 120 enters the resonance space of each Helmholtz resonator through the through-holes 125c to resonate the Helmholtz resonator. This resonance reduces noise.

  FIG. 4 is an exploded plan view showing the optical writing device 47 with the lid member (125a) removed. In the drawing, the laser light source 127 is fixed from the outside to the rear wall of the main body portion 125b. However, the laser emitting portion 127a of the laser light source 127 passes through the through hole (not shown) provided in the rear wall. It has entered the interior of 125b. The laser light emitted from the laser emitting unit 127a sequentially passes through the collimating lens 121 and the cylindrical lens 122, and then reaches one of the six mirror surfaces of the polygon mirror 48 that is rotationally driven. At this time, it is deflected by reflecting at an angle corresponding to the angle of the mirror surface. Depending on the reflection angle, the light travels in a direction deviating from the scanning target region in the main scanning direction, which is the axial direction of the photoconductor (10), and after being reflected on the synchronous mirror 129, after passing through the synchronous lens 124, Received light. Based on this light reception timing, the laser writing timing for the first pixel in the main scanning direction is synchronized.

  When the traveling direction of the laser beam reflected by the mirror surface of the polygon mirror 48 is the direction reaching the scanning target area of the photoconductor (10), the laser beam reflected by the mirror surface is as follows. It reaches the surface of (10). That is, it passes through the scanning lens 128 without hitting the synchronous mirror 129, is reflected by the folding mirror 126 as a reflecting member, and reaches the surface of the photoreceptor (10).

  As shown in the figure, all of the five Helmholtz resonators (141 to 145) in the resonator unit 130 are arranged so that the entrance of the through hole (resonance path) 125c faces the polygon mirror 48 as a deflection mirror.

  FIG. 5 is an exploded perspective view showing the rear end of the optical writing device 47 with the lid member (125a) removed. In the figure, the folding mirror 126 is disposed in the vicinity of the right side wall of the main body part 125b (the wall that also serves as the left side wall of the resonator unit 130) inside the main body part 125b. The three Helmholtz resonators (141 to 143) are interposed between the entrances of the respective through holes (resonance paths) 125 c and the polygon mirror 48. In the drawing, only three of the five Helmholtz resonators are shown, but the folding mirror 126 includes all of the entrances to the through holes (resonance paths) provided in the five Helmholtz resonators, and the polygon mirror. 48.

  FIG. 6 is a partially exploded perspective view showing a part of the optical scanning device 47 in a broken state. FIG. 7 is a partial sectional view showing a part of the optical scanning device 47. The polygon mirror (48 in FIG. 5) not shown in these figures faces the entrance of the through hole (resonance path) 125c of the Helmholtz resonator (141 to 145) via the folding mirror 126. The airflow that has traveled straight from the rotating polygon mirror toward the entrance of the through hole (resonance path) 125c of the Helmholtz resonator (141 to 145) hits the folding mirror 126 before the through hole (resonance path) 125c and changes its direction. To do. In this way, the folding mirror 126 prevents the direct flow of the airflow that travels toward the inlet of the through hole (resonance path) 125c of the Helmholtz resonator (141 to 145) generated by the polygon mirror. Even if a part of the airflow that has been weakened as it changes its direction by hitting the folding mirror 126 becomes turbulent and reaches the entrance of the through hole 125c of the Helmholtz resonator beyond the folding mirror 126, the momentum is weak. There is almost no whistle noise due to the turbulent flow. As described above, the folding mirror 126 prevents the whistle-like noise from being generated by preventing the direct flow of the airflow to the inlet of the through hole (resonance passage) 125c, thereby suppressing an increase in noise due to the whistle noise. be able to. Furthermore, since it is possible to suppress the generation of whistle-like noise without providing a new Helmholtz resonator to reduce whistle-like noise, the cost is increased by providing a new Helmholtz resonator. Can also be avoided. Moreover, the cost can be reduced by sharing the bottom walls of the five Helmholtz resonators with the bottom lid member 125a. Furthermore, the cost can also be reduced by using the left side walls of the five Helmholtz resonators as the right side wall of the main body 125a.

  FIG. 8 is an exploded plan view showing a part of the optical scanning device 47 with the lid member (125a) removed. In the figure, on the inner surface of the right side wall (the wall also serving as the left side wall of the resonator unit 130) in the main body 125 of the housing, a first projecting inner wall 125b-1 and a second projecting projecting toward the inside of the housing. An inner wall 125b-2 is provided. The folding mirror 126 is sandwiched between the first projecting inner wall 125b-1 and the second projecting inner wall 125b-2 in the front-rear direction of the copying machine main body (the longitudinal direction of the folding mirror 126 in the figure). As a result, two sides (one end side and the other end side in the mirror longitudinal direction) of the space between the folding mirror 126 and the front side wall (the side wall provided with the through hole 125c) of the main body 125b inside the housing are separated into two. The projecting inner walls (125b-1, 125b-2) are closed. In such a configuration, even if a part of the airflow hitting the folding mirror 126 on the front side (polygon mirror side) from the folding mirror 126 becomes turbulent and circulates to both sides, the entry into the space is prevented by the projecting inner wall. Is done. Thereby, the increase of the noise by a whistle-like noise can be suppressed more by reducing the quantity of the airflow which reaches | attains the entrance of the through-hole (resonance channel) 125c more.

  As described above, in the copier 500 according to the embodiment, the right side wall of the main body 125b of the housing is also used as the left side wall of the resonator unit 130, and the resonance unit cover 131 is used as the right side wall of the main body 125b. On the other hand, it is fixed from the outside. Further, in this copying machine, through holes (resonances) of five Helmholtz resonators on the optical path of the laser light after passing through the polygon mirror 48 in the casing 125 in a state where the folding mirror 126 as a reflecting member is not provided. (Passage) 125c is disposed. In such a configuration, as shown in FIG. 9, when operating with the folding mirror (126) and the resonance unit cover (131) removed, the laser light after passing through the polygon mirror 48 passes through the through hole 125c. Thus, the light is emitted to the outside of the optical scanning device 47. In such a configuration, when the optical scanning device 47 is manufactured, the beam diameter of the laser light can be measured by the CCD camera 160 or the like disposed outside the optical scanning device 47. Will be able to do. In other words, the collimating lens 121 and the cylindrical lens 122 can be finely adjusted in order to obtain a desired beam diameter at the photosensitive member image surface distance. After performing such fine adjustment, the optical scanning device 47 may be completed by attaching the folding mirror 126 and the resonance unit cover 131.

  Inside the main body 125b, a pair of reflecting walls including a first reflecting wall 125b-3 and a second reflecting wall 125b-4 facing each other along the longitudinal direction of the folding mirror 126 is provided. The two reflecting walls are arranged in such a manner as to be widened from the polygon mirror 48 side toward the resonator unit 130 side while facing each other through the polygon mirror 48. As shown in FIG. 10, the reflecting wall pair composed of these reflecting walls directs the sound that has been generated from the polygon mirror 48 and travels in a direction different from the direction toward the resonator unit 130 toward the resonator unit 130. Reflect. Thereby, noise can be more reliably reduced by reducing the amount of sound leakage from the inside of the housing 125. Since the two reflecting walls are in a diverging posture, the sound that has been generated from the polygon mirror 48 and then traveled to the opposite side of the resonator unit 130 from the polygon mirror 48 is also directed toward the resonator unit 130. Can be reflected.

  In the copying machine 500 according to the embodiment, the pair of reflecting walls is also used as a rib wall for reinforcement, thereby realizing cost reduction.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
[Aspect A]
Aspect A is a deflecting unit (for example, polygon scanner 120) that deflects the traveling direction of light emitted from a light source (for example, laser light source 127) by a deflecting mirror (for example, polygon mirror 48) driven by a driving source (for example, polygon motor 49). And a resonance space for reducing noise emitted from the deflecting means, and a resonance passage (for example, a through hole 125c) communicating with the resonance space for guiding noise from the outside to the inside of the resonance space In an optical scanning device (for example, the optical scanning device 47) having (for example, Helmholtz resonators 141 to 145) and a housing (for example, the housing 125) that accommodates at least the deflecting unit and the reflecting member, an entrance of the resonance path is provided. The deflection mirror is positioned between the mirror surface of the deflection mirror and the entrance while being positioned within the mirror projection area of the deflection mirror. As to interpose a separate optical components (e.g., folding mirror 126) and is characterized in that it has provided the resonator.

  In such a configuration, in the layout in which the resonator is positioned in the mirror projection area of the deflecting mirror, the airflow generated on the mirror surface of the driving deflecting mirror and proceeding straight toward the entrance of the resonant path of the resonator is In front of the entrance, the light hits an optical system component different from the deflecting mirror, and the direction is changed. In this way, another optical system component prevents direct flow of the airflow generated at the mirror surface of the deflecting mirror being driven and traveling toward the entrance of the resonance path of the resonator. Even if a part of the air flow that was weakened as it changed its direction by hitting an optical part other than the deflecting mirror became turbulent and overcame the optical part and reached the entrance of the resonance path, There is not much noise for whistle due to the weak turbulence. In this way, an optical system component other than the deflecting mirror prevents the whistle-like noise from being generated by preventing the direct flow of the airflow to the resonance passage entrance, thereby increasing the noise caused by the whistle noise. Can be suppressed. Furthermore, since it is possible to suppress the generation of whistle-like noise without providing a new resonator to reduce the whistle-like noise, the cost increase due to the provision of a new resonator is avoided. You can also

[Aspect B]
Aspect B is the aspect A in which a plurality of the resonators are provided, and between the entrances of the resonance passages provided in the resonators and the mirror surface of the deflecting mirror, It is characterized by interposing optical system parts. In such a configuration, it is possible to suppress the generation of whistle-like noise caused by the airflow entering the entrance of the resonance passage for all the resonators.

[Aspect C]
Aspect C is the aspect A or B in which the side wall of the casing is also used as the side wall provided with the resonance path of the resonator, and the other side walls of the resonator other than the side wall with respect to the casing. The resonance path is disposed on the optical path of the light after passing through the deflecting mirror in the casing in a state where it is fixed from the outside and the other optical system component is not disposed. is there. In such a configuration, the cost can be reduced by using the side wall of the housing also as the side wall of the resonator. Furthermore, by operating with the other optical system parts and the other side wall removed, the light after passing through the deflecting means is emitted to the outside of the optical scanning device through the resonance path, and the beam is externally provided. The diameter can be measured, and the measurement result can be used for fine adjustment of the optical system component.

[Aspect D]
Aspect D is a reflection wall according to any one of the aspects A to D, wherein a reflection wall that reflects a sound that has been generated from the deflecting mirror and has traveled in a direction different from a direction toward the resonator toward the resonator, It is provided in the housing. In such a configuration, generation of noise can be further suppressed by suppressing sound leakage of light traveling in different directions.

[Aspect E]
Aspect E consists of two reflective walls in aspect D, which are arranged in such a manner that the reflecting walls face each other via the deflecting mirror and are widened from the deflecting mirror side toward the resonator side. The present invention is characterized in that a reflecting wall pair is provided. In such a configuration, even the sound generated by the driving deflecting mirror and traveling in the opposite direction to the resonator can be reflected toward the resonator by the reflecting wall pair.

[Aspect F]
Aspect F is characterized in that, in aspect D or E, the reflection wall is also used as a rib wall for reinforcement. In such a configuration, the cost can be reduced by using the reflecting wall also as the rib wall.

[Aspect G]
Aspect G includes a photosensitive member (for example, the photosensitive member 10) as a scanning object, an optical scanning unit (for example, an optical scanning device 47) that forms a latent image on the photosensitive member by optical scanning, and a developing unit for developing the latent image. An image forming apparatus including (for example, the developing device 12) is characterized in that the optical scanning device according to any one of claims 1 to 6 is used as the optical scanning unit. In such a configuration, while avoiding an increase in noise caused by generating whistle-like noise in the optical scanning device 47, an increase in cost due to provision of a new resonator for reducing the whistle-like noise is avoided. can do.

10: Photoconductor 12: Developing device (developing means)
47: Optical scanning device 48: Polygon mirror (deflection mirror)
49: Polygon motor (drive source)
120: Polygon scanner (deflection means)
125: Housing 125a: Lid member 125b: Main body 125c: Through hole (resonance path)
126: Folding mirror (another optical component)
130: Resonator unit 131: Resonance unit cover (other side walls, etc.)
141; first Helmholtz resonator 142; second Helmholtz resonator 143; third Helmholtz resonator 144; fourth Helmholtz resonator 145; fifth Helmholtz resonator 500: copier (image forming apparatus)

JP 2005-202117 A

Claims (7)

Deflection means for deflecting the traveling direction of light emitted from a light source by a deflection mirror driven by a drive source, a resonance space for reducing noise emitted from the deflection means, and noise from outside the resonance space In an optical scanning apparatus comprising: a resonator including a resonance path that communicates with the resonance space for guiding; and a housing that houses at least the deflecting unit and the reflecting member.
The resonance path is arranged such that an optical system component different from the deflecting mirror is interposed between the mirror surface of the deflecting mirror and the entrance, while the entrance of the resonance path is located in the specular projection region of the deflecting mirror. An optical scanning device characterized in that an optical device is provided. The optical scanning device according to claim 1,
A plurality of the resonators are provided,
In addition, the optical scanning device is characterized in that the another optical system component is interposed between all of the entrances of the resonance paths provided in the plurality of resonators and the mirror surface of the deflecting mirror. . The optical scanning device according to claim 1 or 2,
The side wall of the casing is also used as a side wall provided with the resonance path of the resonator, the other side wall of the resonator except the side wall is fixed to the casing from the outside, and the other side An optical scanning device characterized in that the resonance path is disposed on an optical path of light after passing through the deflecting mirror in the casing in which no optical system component is disposed. The optical scanning device according to any one of claims 1 to 3,
An optical scanning device characterized in that a reflection wall is provided in the housing for reflecting a sound generated from the deflecting mirror and traveling in a direction different from a direction toward the resonator toward the resonator. . The optical scanning device according to claim 4.
As the reflecting wall, a reflecting wall pair comprising two reflecting walls disposed in a posture that spreads from the deflecting mirror side toward the resonator side while facing each other via the deflecting mirror is provided. An optical scanning device. The optical scanning device according to claim 4 or 5,
An optical scanning device characterized in that the reflection wall is also used as a rib wall for reinforcement. In an image forming apparatus comprising: a photosensitive member that is a scanning object; an optical scanning unit that forms a latent image on the photosensitive member by optical scanning; and a developing unit that develops the latent image.
An image forming apparatus using the optical scanning device according to claim 1 as the optical scanning unit.

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