JP2006195288A - Optical writing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical writing device whose noise prevention and heat discharge are compatible when a rotary polygon mirror is installed. <P>SOLUTION: The optical writing device 8 which deflects a light beam from a light source by the rotary polygon mirror 142 to perform a scan is equipped with: a rotary polygon mirror surrounding portion 200 which can rotatably support the rotary polygon mirror 142 and is composed of a partially open space 201; and a duct portion 210 which is attachable to and detachable from the open portion 201 of the rotary polygon mirror surrounding portion 200 and has an opening portion 210A communicating at the time of loading. The open portion 201 on the side of the rotary polygon mirror surrounding portion 200 and the opening portion 210A on the side of the duct 210 are made continuous via a shield member 211 shielding their communication portions from the outside. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical writing device and an image forming apparatus, and more particularly to a heat exhaust mechanism from a heat generating portion.

  In an image forming apparatus such as a copying machine, a printer, or a facsimile machine, an optical writing apparatus using a light beam such as a laser beam as one of apparatuses for forming an electrostatic latent image on a photosensitive member used as a latent image carrier. May be used (for example, Patent Documents 1 and 2).

  On the other hand, the optical writing apparatus uses a plurality of laser light sources and forms an image including a rotating polygon mirror that uses the light beams emitted from these light sources as deflection means, an fθ lens, a surface tilt correction lens, and a mirror. There has also been proposed a multicolor image forming apparatus capable of forming an image corresponding to image information on each photoconductor by guiding to a plurality of photoconductors via means (for example, Patent Document 3).

  In recent years, higher image forming processing speed and higher recording density have been demanded. As a method for realizing this, the rotational speed of a rotary polygon mirror used in a writing optical system is increased. May be faster.

When the speed of the rotating polygon mirror is increased, the wind noise of the polygon mirror becomes conspicuous, and further, the heat generation at the bearing portion that pivotally supports the polygon mirror also becomes significant.
For this reason, conventionally, there has been proposed an optical writing device having a configuration for preventing noise from leaking from the installation portion of the rotary polygon mirror and a configuration for dissipating heat from the support portion of the rotary polygon mirror ( For example, Patent Documents 4 to 7).

  As a configuration for preventing noise from the installation portion of the rotary polygon mirror, as disclosed in Patent Documents 4 to 7, a configuration in which the rotary polygon mirror is disposed in a substantially sealable space is known. As a configuration for heat dissipation, a configuration in which a heat dissipation member partially exposed to a rotating polygon mirror located in a sealed space is exposed to the outside of the sealed space to dissipate heat and a configuration in which airflow is generated in the sealed space are known. Yes.

JP-A-6-148553 Japanese Patent Laid-Open No. 10-232360 JP 2002-137450 A Japanese Patent Laid-Open No. 11-271661 Japanese Patent No. 3550008 JP 11-119138 A JP 2001-337291 A

When a rotating polygon mirror is provided in a space with a hermetically sealed structure, noise leakage can be prevented, but there is a risk of heat stagnating inside.
In the case of a configuration in which the heat radiating member is exposed to the outside of the sealed space, it becomes difficult to secure a heat radiating amount commensurate with the rotation increase of the rotary polygon mirror because the heat absorbing ability of the heat radiating member is limited. There is a fear. Further, in the case of a configuration in which an air flow is generated in the sealed space, there is a possibility that the lubricant in the bearing portion may be denatured because the increase in the temperature in the space cannot be suppressed unless the hot air is reliably retained. In addition, the spatial structure may be complicated depending on the airflow setting.

When exhausted toward the vicinity of the space, it is made of a resin used in the optical system due to a rise in the temperature of the peripheral part when the air is exhausted in the vicinity of the rotating polygon mirror in the optical writing device equipped with the rotating polygon mirror. There is a risk that the imaging optical path may change due to the deformation of the lens or the like, and if the space is open at a communication position with the outside, noise may leak from the opening.
Further, when exhausting into the image forming apparatus outside the optical writing apparatus instead of exhausting into the optical writing apparatus in the vicinity of the sealed space, a temperature rise in the image forming apparatus is caused. There is a risk of causing thermal degradation of the parts used.

  An object of the present invention is to provide an optical writing apparatus and an image forming apparatus having a configuration capable of achieving both problems with the above-described conventional optical writing apparatus, particularly noise prevention and exhaust heat when a rotary polygon mirror is provided. It is in.

  The invention according to claim 1 is an optical writing device having a structure in which a light beam from a light source is deflected and scanned by a rotating polygon mirror, and is located at a peripheral portion of the rotatable rotating polygon mirror, and a part thereof A rotating polygon mirror surrounding portion configured by an open space; and a duct portion that is detachable from the opening portion of the rotating polygon mirror surrounding portion and has an opening communicating with the rotating polygon mirror surrounding portion. The opening portion on the rotary polygon mirror surrounding portion side and the opening portion on the duct side are configured to be continuous through a shielding member that shields the communication portion from the outside.

  According to a second aspect of the present invention, in the optical writing device according to the first aspect, the shielding member is arranged in contact with a reinforcing protrusion provided on the rotary polygon mirror surrounding portion side at the communication position. It is characterized by being.

  According to a third aspect of the present invention, in the optical writing device according to the first or second aspect, the duct portion is provided with an exhaust portion at a position different from an opening portion that can communicate with the opening portion on the rotary polygon mirror surrounding portion side. And an intake section, the opening is formed in the middle of the exhaust section and the intake section, and an airflow generating means is provided in either the exhaust section or the intake section.

  According to a fourth aspect of the present invention, in the optical writing device according to any one of the first to third aspects, a foamed member is used as the shielding member.

  According to a fifth aspect of the present invention, in the optical writing device according to the fourth aspect of the present invention, a part of the internal space of the duct part is opened between the exhaust part and the intake part in the duct part to generate an air flow. A plurality of sound-absorbing members made of a foam member that partitions in a state in which passage is allowed are provided.

  According to a sixth aspect of the present invention, in the optical writing device according to the fifth aspect, the sound absorbing member is disposed in the vicinity of an airflow generating means provided in either the exhaust portion or the intake portion. Yes.

  A seventh aspect of the invention is characterized in that the optical writing device according to one of the first to sixth aspects is used for an image forming apparatus.

  According to the first aspect of the present invention, by providing the duct portion having the opening portion formed on the rotating polygon mirror surrounding portion side and the opening communicating with the opening portion, the heat in the rotating polygon mirror surrounding portion is transferred to the duct portion side. In addition, the noise generated from the rotary polygon mirror can be prevented from leaking to the outside by the hand being shielded from the outside by the shielding member at the communicating portion.

  According to invention of Claim 2, since the shielding member is made to contact the reinforcement protrusion provided in the rotation polygon mirror enclosure part side, the contact pressure on the rotation polygon mirror enclosure part side with respect to the shielding member is utilized. It becomes possible to secure the exhaust heat and noise prevention characteristics by improving the adhesion of the shielding member pair.

  According to the invention described in claim 3, since a forced air flow is generated in the duct portion, the heat generated in the rotating polygon mirror enclosure portion is forcibly discharged, so that the radiation in the rotation polygon mirror enclosure portion is released. In addition to improving the thermal characteristics, it is possible to reliably prevent noise from leaking to the outside, including airflow noise when forced airflow is generated by installing a shielding member at the communication portion.

  According to the invention described in claim 4, since the shielding member is a foamed member, it is possible to obtain an improvement in sound absorption characteristics.

  According to the fifth aspect of the present invention, since the sound absorbing member made of the foam member that partitions the air flow in the duct is provided in the duct, the air current detours and moves while colliding with the sound absorbing member. Propagation of noise is weakened, and generation of noise can be suppressed by absorbing vibration due to collision.

  According to the sixth aspect of the present invention, since the sound absorbing member is provided in the vicinity of the airflow generation means, it is possible to suppress noise from the airflow generation means in addition to the airflow sound.

  According to the seventh aspect of the present invention, the heat generated in the rotary polygon mirror surrounding portion can be efficiently discharged, thereby eliminating problems such as writing defects caused by the thermal deterioration of the optical element due to the temperature rise in the peripheral portion. In addition, it is possible to reliably prevent the generation of noise.

  The best mode for carrying out the present invention will be described below with reference to embodiments shown in the drawings.

  FIG. 1 shows an image forming apparatus to which an optical writing apparatus using a reflection mirror as a flat plate member according to an embodiment of the present invention is applied. The image forming apparatus shown in FIG. Although there is a color printer using a tandem system in which image portions are juxtaposed along the belt extending direction, the present invention is not limited to this system, and may be applied not only to a printer but also to a copier or a facsimile machine. Is possible.

Referring to FIG. 1, the schematic configuration of the image forming apparatus 100 will be described. The image forming apparatus 100 is capable of forming an image as an image corresponding to each color separated into yellow, cyan, magenta, and black. A tandem structure in which photoconductor drums 20Y, 20C, 20M, and 20Bk are juxtaposed is employed.
In the image forming apparatus 100 having the configuration shown in FIG. 1, the visible images formed on the photosensitive drums 20Y, 20C, 20M, and 20Bk are in the direction of arrow A1 while facing the photosensitive drums 20Y, 20C, 20M, and 20Bk. A transfer sheet S on which an image is superimposed and transferred by performing a primary transfer process on an intermediate transfer body (hereinafter referred to as a transfer belt) 11 using a movable endless belt, and thereafter a recording sheet or the like is used. On the other hand, batch transfer is performed by executing a secondary transfer process.

  Around each photosensitive drum, an apparatus for image formation processing is arranged according to the rotation of the photosensitive drum. Now, the photosensitive drum 20Bk that performs black image formation will be described as an object. A charging device 30Bk, a developing device 40Bk, a primary transfer roller 12Bk, and a cleaning device 50Bk that perform image forming processing along the rotation direction are arranged. As will be described later, the optical writing device 8 is used for writing performed after charging.

  The superimposed transfer onto the transfer belt 11 is performed on each of the photosensitive drums 20Y, 20C, 20M, and 20Bk in the process in which the transfer belt 11 made of a resin film or rubber having a substrate thickness of about 50 to 600 μm moves in the A1 direction. The primary transfer arranged so as to face each of the photosensitive drums 20Y, 20C, 20M, and 20Bk with the transfer belt 11 interposed therebetween so that the formed visible image is transferred to the same position on the transfer belt 11. The timing is shifted from the upstream side toward the downstream side in the A1 direction by voltage application by the rollers 12Y, 12C, 12M, and 12Bk.

  The photosensitive drums 20Y, 20C, 20M, and 20Bk are arranged in this order from the upstream side in the A1 direction. Each of the photosensitive drums 20Y, 20C, 20M, and 20Bk is provided in an image station for forming yellow, cyan, magenta, and black images.

The image forming apparatus 100 is disposed so as to face four image stations that perform image forming processing for each color and above each of the photosensitive drums 20Y, 20C, 20M, and 20Bk, and includes a transfer belt 11 and a primary transfer roller 12Y. , 12C, 12M, and 12Bk, a secondary transfer roller 5 that is a transfer roller as a transfer member that is arranged to face the transfer belt 11 and that is driven by the transfer belt 11 and rotates. An intermediate transfer belt cleaning device 13 disposed opposite to the transfer belt 11 for cleaning the transfer belt 11, and an optical writing device 8 serving as an optical writing device disposed below these four image stations. And have.
The optical writing device 8 in the present embodiment is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygon mirror as a deflecting means, and the like. Write light Lb corresponding to each color with respect to 20C, 20M, and 20Bk (in FIG. 1, for convenience, a sign is given only for the image station of the black image, but the same applies to the other image stations). Thus, an electrostatic latent image is formed on the photosensitive drums 20Y, 20C, 20M, and 20Bk. The configuration related to the optical writing device 8 will be described in detail later.

  The image forming apparatus 100 includes a sheet feeding device 61 serving as a sheet feeding cassette on which transfer sheets S transported between the photosensitive drums 20Y, 20C, 20M, and 20Bk and the transfer belt 11 are stacked. The transfer section between each of the photosensitive drums 20Y, 20C, 20M, and 20Bk and the transfer belt 11 is fed with the recording sheet S conveyed from the feeding device 61 at a predetermined timing in accordance with the toner image formation timing by the image station. And a sensor (not shown) for detecting that the leading edge of the transfer sheet S has reached the registration roller pair 4.

  The image forming apparatus 100 includes a fixing device 6 as a roller fixing type fixing unit for fixing the toner image to the transfer paper S on which the toner image is transferred, and the main body of the image forming apparatus 100 with the fixed transfer paper S A paper discharge roller 7 that discharges to the outside, a paper discharge tray 17 that is disposed on the top of the main body of the image forming apparatus 100 and loads the transfer paper S discharged to the outside of the main body of the image forming apparatus 100 by the discharge roller 7, and paper discharge Toner bottles 9Y, 9C, 9M, and 9Bk are provided below the tray 17 and filled with toners of yellow, cyan, magenta, and black.

  The transfer belt unit 10 includes a drive roller 72 and a driven roller 73 around which the transfer belt 11 is wound, in addition to the transfer belt 11 and the primary transfer rollers 12Y, 12C, 12M, and 12Bk.

  The driven roller 73 also has a function as a tension urging unit for the transfer belt 11. For this reason, the driven roller 73 is provided with an urging unit using a spring or the like. Such a transfer belt unit 10, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, the secondary transfer roller 5, and the cleaning device 13 constitute a transfer device 71.

  The sheet feeding device 61 is disposed at the lower part of the main body of the image forming apparatus 100, and includes a feeding roller 3 as a feeding roller that contacts the upper surface of the uppermost transfer sheet S. The uppermost transfer sheet S is fed toward the registration roller pair 4 by being rotationally driven 3 in the counterclockwise direction.

  The fixing device 6 includes a fixing roller 62 having a heat source therein, and a pressure roller 63 pressed against the fixing roller 62. The fixing sheet 62 carrying the toner image is transferred to the fixing roller 62 and the pressure roller 63. By passing through a fixing portion that is a pressure contact portion, the carried toner image is fixed on the surface of the transfer paper S by the action of heat and pressure.

  Although not shown in detail, the cleaning device 13 provided in the transfer device 71 has a cleaning brush and a cleaning blade disposed so as to face and contact the transfer belt 11. The transfer belt 11 is cleaned by scraping and removing foreign matter such as residual toner on the top with a cleaning brush and a cleaning blade. The cleaning device 13 also has a discharge means (not shown) for carrying out and discarding the residual toner removed from the transfer belt 11. In the image forming apparatus 100 having the configuration shown in FIG. 1, the images formed on the photosensitive drums are sequentially transferred onto the transfer belt 11, and the color images superimposed are transferred by the secondary transfer roller 5. In this method, the transfer sheet S is transferred to the sheet S. Alternatively, the transfer sheet S is carried on the transfer belt 11 and the transfer sheet S is opposed to each photosensitive drum so that each color image is directly transferred onto the transfer sheet S. It is also possible to use a superposition method.

  FIG. 2 is a diagram showing the optical writing device 8, in which the optical writing device 8 has a housing 131 and an optical element holding member 132 as a holding member.

The housing 131 exhibits a function to prevent dust, which will be described later, and includes a housing body 131a having an upper surface opening and a lid cover 131b (see FIG. 3) for closing the opening portion of the housing body 131a. ing.
The housing main body 131a and the lid cover 131b are made of resin and have an inexpensive and lightweight structure.
The lid cover 131b is formed with four openings 133 through which the laser light indicated by the symbol Lb in FIG. 3 passes. These openings 133 allow the laser light Lb to pass therethrough and restrict the entry of dust. A dustproof member 134 is attached. As the dustproof member 134, for example, flat glass can be used.
In FIG. 2, a connecting portion 135 for connecting the casing 131 to the frame of the main body is formed on the side surface of the casing main body 131a, and the connecting portion 135 is fitted into a recess (not shown) formed in the frame. By combining, the optical writing device 8 is connected to the main body.

The optical element holding member 132 is a frame-like member made of metal, specifically made of iron, which is the same material as the frame of the main body. The optical element holding member 132 includes a side surface portion 132a as a pair of end portion holding members facing substantially parallel to each other. And a stay 132b as a connecting member for connecting the side surface portions 132a at a substantially central portion of the side surface portion 132a. Since the optical element holding member 132 is made of metal, specifically made of iron, its linear expansion coefficient is smaller than that of the casing 131 made of resin.
The optical element holding member 132 is accommodated in the housing 131 and is fixed to the housing 131 at two locations on the same inner surface by screws (not shown).

  The optical writing device 8 is emitted from light source units 141Y, 141C, 141M, 141Bk as LD units serving as four light sources that oscillate light beams as writing light of each color, and light source units 141Y, 141C, 141M, 141Bk. The light beam deflected and scanned by the rotary polygon mirror 142 as the deflecting means that distributes and scans the two beams in two symmetrical directions and deflects and scans the photosensitive drums 20Y, 20C, 20M, and 20Bk ( And a scanning lens 143 that is a pair of fθ lenses that form an image with a desired size on the surface to be scanned (see FIG. 3).

  In addition, a surface tilt correction aperture 152 and a cylinder lens 153 are disposed between the light source units 141Y, 141C, 141M, and 141Bk and the rotary polygon mirror 142.

  In the present embodiment, as a configuration for allowing two light beams to be incident independently from one side of the rotary polygon mirror 142, the light beam is returned to the incident path of the light beam from the light source unit corresponding to one side to the rotary polygon mirror 142. An incident path in which the mirror 145a is provided and an incident path in which the folding mirror 145a is not provided are set. Thereby, the incident angle in the main scanning direction with respect to the rotary polygon mirror 142 can be made different between the light beams incident on one side, and the light beam is shaped to form an imaging means for the photosensitive drum which is the spot irradiation position. The light beam from the scanning lens 143 using the fθ lens is diverged. As a result, the two light beams incident on the optical deflector 145a are separated from each other in the main scanning direction. In this way, by separating the two light beams corresponding to one side with respect to the rotary polygon mirror 142, even when the scanning lenses 143 made of fθ lenses are stacked in the thickness direction, the light beams are applied to the respective scanning lenses 143. It becomes possible to diverge. Therefore, unlike the case where the scanning lens 143 emits an independent light beam at an interval in the height direction, the installation space in the thickness direction of the scanning lens 143 can be reduced.

  In addition, as with the scanning lens 143, the rotating polygon mirror 142 that independently enters each light beam in the thickness direction also allows the light beam to be directed in different directions by simply changing the incident angle on the same incident surface. Since it can diverge, it is not necessary to increase the height of the rotating polygonal mirror 142 in the thickness direction. As a result, it is possible to prevent an increase in the rotational load on the drive motor that occurs when the height in the thickness direction is increased, thereby enabling high-speed rotation.

On the other hand, the folding mirror is not only intended for the incident path to the rotary polygon mirror 142 described above, but also to the incident paths to the photosensitive drums 20Y, 20C, 20M, and 20Bk, as shown in FIG. It is provided as shown by.
Therefore, the aperture 152, the cylinder lens 153, the scanning lens 143, and the folding mirrors 145a and 145b form an image of the beams on the scanned surfaces of the photosensitive drums 20Y, 20C, 20M, and 20Bk in each set through which the beams pass. These optical element groups are formed.

  The optical element holding member 132 is an optical member provided in the optical writing device 8, that is, the light source units 141Y, 141C, 141M, 141Bk, the aperture 152, the cylinder lens 153, the rotary polygon mirror 142, the scanning lens 143, and the folding mirrors 145a, 145b. Of the synchronous detection optical system element 144, only the folding mirror 145b is held, and the other optical members are held by the casing 131.

As a result, the optical element holding member 132 holds only the folding mirror 145b among the aperture 152, the cylinder lens 153, the scanning lens 143, and the folding mirrors 145a and 145b, which are a plurality of optical elements constituting the optical element group described above. It is held as an optical element.
Each folding mirror 145b is a long mirror, and the optical element holding member 132 holds each end of each folding mirror 145b on the side surface portion 132a.

  The casing 131 holds the aperture 152, the cylinder lens 153, the rotary polygon mirror 142, the scanning lens 143, the folding mirror 145a, and the synchronization detection optical system element 144 among the optical members described above on the upper surface of the holding portion 131c.

  The casing 131 is an optical member provided in the optical writing device 8, that is, the light source units 141Y, 141C, 141M, 141Bk, the aperture 152, the cylinder lens 153, the rotary polygon mirror 142, the scanning lens 143, the folding mirrors 145a, 145b, 145c. All of the synchronous detection optical system elements 144 are accommodated to protect them from dust. Note that a member denoted by reference numeral 147 in the light source units 141Y, 141C, 141M, and 141Bk is a collimating lens that substantially collimates the diverging light emitted from the semiconductor laser.

  The rotary polygon mirror 142 used as an optical deflector is provided in two stages, and is driven by a polygon motor 150 as a driving means for rotating at a high speed of 20,000 to 50,000 rpm. The polygon motor 150 is rotationally controlled by a drive circuit (not shown). A stay 132b is located above the rotating polygon mirror 142 at a position facing the rotating polygon mirror 142.

  As will be described later, the area around the rotating polygon mirror 142 is sealed in a range excluding the bottom surface by the rotating polygon mirror surrounding member 200 made of soundproof glass or the like for preventing noise leakage that occurs during high-speed rotation exceeding 30,000 rpm. Has been.

  The synchronization detection optical system element 144 includes a synchronization detection mirror 144a, an imaging lens 144b, a photoelectric element 144c, an electric circuit board 144d integrally including the photoelectric element 144c, the synchronization detection mirror 144a, and an imaging lens. 144b, a photoelectric element 144c, and a detection optical system holding member (not shown) that holds the photoelectric element 144.

  In the optical writing device 8 having such a configuration, color separation corresponding to image information received and input from the outside of the image forming device 100, for example, an image data output device such as a personal computer, a word processor, or a facsimile receiving unit. The converted image data is converted into a light source driving signal, and the semiconductor laser 46 in each of the light source units 41Y, 41C, 41M, 41Bk is driven accordingly to emit a beam. When the image forming apparatus 100 includes a document reading device such as a scanner, the color-separated image data corresponding to the image information is used as a light source driving signal based on the image read by the document reading device. Conversion is performed and each semiconductor laser is driven to emit a beam.

  The light beams emitted from the light source units 141Y, 141C, 141M, and 141Bk reach the rotating polygon mirror 142 via the aperture 152, the cylinder lens 153, and the folding mirror 145a (only the beams emitted from the light source units 141Y and 141K). Then, the scanning is deflected and scanned in two symmetric directions by the rotary polygon mirror 142 rotated at a constant speed and at a high speed by the polygon motor 150. At this time, the light beams from the two light source units located on one side are incident on the light beam that is reflected by the folding mirror 145a and is incident on the rotary polygon mirror 142 without passing through the mirror 145a and the incident angle in the main scanning direction. By making different, it will diverge in different directions.

  The light beams deflected and scanned in two directions by the rotating polygon mirror 142 in two directions pass through the scanning lens 143, are folded back by the folding mirror 145b, and only the beams emitted from the light source units 141C and 141M are reflected by the folding mirror 145c. The image is folded, transmitted through the dust-proof member 134, and spot-irradiated onto the photosensitive drums 20Y, 20C, 20M, and 20Bk as laser light L to write an electrostatic latent image. At this time, the irradiation angles of the four laser beams L to the photosensitive drums 20Y, 20C, 20M, and 20Bk are almost the same.

  On the other hand, the synchronization detection optical system element 144 for determining the timing of starting writing returns the beam that has passed through the scanning lens 143 by the synchronization detection mirror 144a, receives the light through the imaging lens 144b, and is received by the photoelectric element 144c. Output the start sync signal. Here, since the original meaning of the synchronization detection is to take the timing of the scanning light, the synchronization detection optical system element 44 may be installed so as to receive the beam prior to the normal scanning. In order to detect a change in the speed or time of one scan, it may be detected also at the rear end of the scan. In this embodiment, such a configuration is adopted that synchronizes before and after the scan. .

This embodiment is characterized by the support portion of the rotary polygon mirror 142. Hereinafter, this configuration will be described.
FIG. 4 is a schematic diagram showing the rotary polygon mirror 142 extracted. In FIG. 4, the rotary polygon mirror 142 is located inside the rotary polygon mirror enclosure 200 formed of a housing capable of sealing a space excluding the bottom surface. The rotating polygon mirror enclosure 200 is integrated with the bottom surface placed on the optical element holding member 132.

  The bottom surface side of the rotary polygon mirror enclosure 200 is open, and the bottom surface of the optical element holding member 132 and the bottom surface of the housing 131 that face the open surface are shown in a range excluding the support bridge portion of the polygon motor 150. 4 is formed in an annular through hole 201 in a plan view as viewed from the upper side of the paper surface, and the rotating polygon mirror holding member 200 constitutes a partially open space.

A detachable duct member 210 can face the through-hole 201 that forms an open portion of the rotary polygon mirror enclosure 200.
The duct member 210 includes an annular opening 210a in plan view that can communicate with the penetrating part 201, and exhausts at both ends in the airflow direction corresponding to the direction of movement along the opening 210a at a position different from the opening 210a. It is comprised with the hollow member provided with the part 210b and the intake part 210c, respectively.

A shielding member 211 is disposed between the opening 210a in the duct member 210 and the through hole 201 facing the opening 210a, and the communication portion between the opening 210a and the through hole 201 is externally connected via the shielding member 211. And are connected in a blocked state.
In the present embodiment, a foaming member that can absorb and relax vibrations of the rotating polygonal mirror enclosure 200 and prevent the propagation of sound waves is used as the shielding member 211.

  As shown in FIG. 5, the duct member 210 is inserted so that the opening 210a faces the through-hole 201 of the rotary polygon mirror surrounding portion 200 in the optical writing device 8, and at this time, the shielding member By disposing 211 in the vicinity of the facing surface between the through hole 201 and the opening 210a and the support bridge portion of the polygon motor 150, the communication portion and the outside are shielded. In FIG. 5, the opening 210 a in the duct member 210 corresponds to the form of the penetrating part 201 in the rotary polygon mirror surrounding part 200, and the form of the opening excluding the position corresponding to the support bridging part of the polygon motor 150. However, the present invention is not limited to this, and it is possible to form a circular hole shape instead of an annular shape without having a portion corresponding to the supporting bridging portion.

  As shown in FIG. 6, the shielding member 211 is in the vicinity of the periphery of the through-hole 201 among the reinforcing protrusions such as ribs provided on the bottom surface of the casing main body 131 a in which the rotary polygon mirror enclosure 200 is loaded. Or it arrange | positions in the state which contacted the projection part 131d located in the bridge | crosslinking part for support of the polygon motor 150, and is received by the duct member 210 side. For this reason, by arranging the housing 130 side so that the reinforcing protrusion 131d bites into the shielding member 211, the shielding member 211 and the housing 131 on the side where the rotary polygon mirror enclosure 200 is loaded in the communication portion. Adhesion is enhanced and the shielding effect from the outside is enhanced.

  FIG. 7 shows a state in which the duct member 211 is detached from the casing 120 in which the rotary polygon mirror enclosure 200 is loaded.

  Since the present embodiment is configured as described above, the duct member 210 is opened from the outside of the optical writing device 8 to the through hole 201 provided in the optical writing device 8 as shown in FIG. Are inserted into the image forming apparatus 100 in a state of facing each other, and the penetrating part 201 is connected to the opening part 210a through the shielding member 211 as shown in FIG. Thereby, since the hot air generated in the rotary polygon mirror surrounding part 200 can be discharged into the duct member 210 via the penetrating part 201, the hot air can be discharged into the duct member 210. As a result, by suppressing the temperature rise inside the rotary polygon mirror surrounding portion 200, it is possible to prevent problems such as thermal deterioration of the lubricant due to the temperature rise at the bearing portion.

  On the other hand, the opening 210 a in the duct member 210 is connected to the through-hole 201 in the rotary polygon mirror enclosure 200 using the shielding member 211, so that the rotary polygon mirror 142 generated in the rotary polygon mirror enclosure 200 can be obtained. Wind noise can be prevented from leaking outside.

  By the way, when the opening 210a in the duct member 210 is merely connected to the through-hole 201 of the rotary polygon mirror enclosure 200 via the shielding member 211, the hot air flows out from the inside of the rotary polygon mirror enclosure 200. The state depends only on the difference in density from the air present in the duct member 210, that is, the difference in air density due to the degree of expansion due to temperature. For this reason, the case where the hot air in the rotary polygon mirror surrounding part 200 does not flow smoothly can be considered. Therefore, in this embodiment, there may be a configuration for forcibly discharging hot air in the rotary polygon mirror enclosure 200.

  In FIG. 4, the duct portion 210 is provided with a fan 212 in the exhaust portion 210 b corresponding to either the exhaust portion 210 b or the intake portion 210 c, and as indicated by an arrow in FIG. 5 due to the rotation of the fan 212. In addition, a forced air flow is generated in the duct portion 210. When the fan 212 is disposed on the exhaust part 210b side, a form that discharges air in the duct 210 is used, and when it is disposed on the intake part 210c side, a form that takes in outside air is used.

  In the present embodiment, since the exhaust part 210b and the intake part 210c in the duct member 210 are communication parts with the outside, the foam member for preventing leakage of noise from the inside of the rotary polygon mirror enclosure part 200 is used. The sound absorbing members 213 and 214 are provided.

The duct member 210 opens a part of the internal space of the duct member 210 along the flow direction of the airflow to move the airflow in a diverted state instead of rectifying the air in the internal space, thereby allowing the airflow to pass. A plurality of partition wall sound absorbing members 215 that can be partitioned in an allowed state are provided along the airflow direction, and the partition wall sound absorbing member 215 is formed of a foam member.
The partition wall sound-absorbing member 215 has an arrangement configuration in which the portion that allows the passage of the airflow is positioned in a direction perpendicular to the moving direction of the airflow, whereby the air flowing inside the duct member 210 is separated from the partition wall. By colliding with the sound absorbing member 215, it is buffered and the propagation of the vibration wave is weakened, and noise leakage is suppressed. In addition, since a forced air flow is generated by the discharge fan 12 in the duct member 210, the internal pressure of the rotary polygon mirror enclosure 200 is different from the internal pressure of the duct member 210 and the internal pressure of the rotary polygon mirror enclosure 200. The hot air is forced to flow into the duct member 210. That is, since the flow velocity is generated inside the duct member 210 and the inside of the rotating polygon mirror surrounding portion 200 tends to become negative pressure, the air from the inside of the rotating polygon mirror surrounding portion 200 can smoothly flow out.

Next, a modification of the main part of the present embodiment will be described.
FIG. 8 shows an example in which the arrangement position of the discharge fan 212 provided in the duct member 210 is different from that shown in FIG. 4. In this figure, the discharge fan (indicated by reference numeral 212 ′ for convenience) It is arranged not in the portion 210b but in the vicinity of the opening 210a.
In this configuration, an opening sound absorbing member (indicated by reference numeral 213 ′ for convenience) for preventing leakage of noise to the outside is disposed in the exhaust part 210b.

  According to this configuration, exhaust by the discharge fan 212 ′ is performed at a position close to the rotary polygon mirror enclosure portion 200, so that the exhaust from the inside of the rotary polygon mirror enclosure portion 200 is performed more smoothly, and in the duct member 210. Opportunity to leak the noise from the discharge fan 212 ′ to the outside by the sound absorbing member 213 ′ for the opening provided in the exhaust part 210B by disposing the discharge fan 212 ′ as a noise source inside the exhaust part 210b. Can be reduced.

1 is a diagram for explaining a configuration of an image forming apparatus to which an optical writing device according to an embodiment of the invention is applied. FIG. It is a figure for demonstrating the member with which the optical writing device by the Example of this invention is equipped. It is a figure for demonstrating the structure of the housing | casing used for the optical writing apparatus by an Example of this invention. It is a schematic diagram for demonstrating the principal part structure of the optical writing apparatus by a present Example. FIG. 5 is a schematic diagram for explaining an aspect of a duct member used in a main part of the optical writing device shown in FIG. 4. In FIG. 5, it is a typical arrow view of the direction shown by code | symbol (6). It is a figure which shows the state which removed the duct member in the arrow line view shown in FIG. It is a figure which shows the partial modification of the structure shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 8 Optical writing apparatus 100 Image forming apparatus 131 Case 131d Reinforcing protrusion 132 Optical element holding member 142 Rotating polygon mirror 200 Rotating polygon mirror surrounding member 201 Through hole as an opening portion 210 Shielding member 210a Opening portion 210b Exhaust portion 210c Intake portion 211 Shielding members 212 ′, 212 ′ Discharge fan 213, 214 Sound absorbing member 213 ′ Open both sound absorbing member 215 Sound absorbing member for partition wall

Claims (7)

In an optical writing device having a configuration in which a light beam from a light source is scanned by deflecting light with a rotating polygon mirror,
A rotary polygon mirror surrounding part that is located in the periphery of the rotatable rotary polygon mirror and is configured by a partly open space;
It is detachable with respect to the opening part of the rotating polygon mirror surrounding part, and includes a duct part in which an opening part that communicates at the time of mounting is formed,
The optical writing device according to claim 1, wherein the opening portion on the rotary polygon mirror surrounding portion side and the opening portion on the duct side are configured to be continuous through a shielding member that shields the communication portion from the outside. The optical writing device according to claim 1,
The optical writing device according to claim 1, wherein the shielding member is arranged in contact with a reinforcing protrusion provided on the rotary polygon mirror surrounding portion side at the communication position. The optical writing device according to claim 1 or 2,
The duct portion is provided with an exhaust portion and an intake portion at a position different from the opening portion that can communicate with the opening portion on the rotary polygon mirror surrounding portion side, and the opening portion is formed in the middle of the exhaust portion and the intake portion. And an airflow generating means provided in either the exhaust part or the intake part. The optical writing device according to claim 1,
An optical writing apparatus, wherein a foaming member is used as the shielding member. The optical writing device according to claim 4.
Between the exhaust part and the intake part in the duct part, there are provided a plurality of sound absorbing members made of foamed members that partition in a state in which a part of the internal space of the duct part is opened and the passage of airflow is allowed. An optical writing device. The optical writing device according to claim 5.
The optical writing device, wherein the sound absorbing member is disposed in the vicinity of an air flow generating means provided in either the exhaust part or the intake part. An image forming apparatus using the optical writing device according to claim 1.

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