JP2006047822A - Image forming apparatus and scanning unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and a scanning unit in which further miniaturization (particularly reduction in height and thickness) can be contrived through a thin profile of a scanning lens. <P>SOLUTION: With the purpose of making a laser beam surely pass through a scanning lens, an LD holder 270 to be mounted with a laser diode is adjusted in the vertical position. In the meantime, the LD holder 270 is stuck in the lower end to a unit frame 200 with an adhesive with an interval from the surface of a base 220 on which a polygon mirror 110 is fixed, thereby stabilizing a positional relation between the LD holder 270 and the unit frame 200. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and a scanning unit, and more particularly to an image forming apparatus including a scanning unit that emits a light beam to expose and scan the surface of a photoreceptor, and a scanning unit provided in the image forming apparatus.

  In an electrophotographic image forming apparatus such as a laser printer, a uniformly charged surface of a photoconductor is deflected by a deflector such as a polygon mirror by a light beam emitted from a light emitting unit including a light source such as a semiconductor laser. Is exposed and scanned to form a latent image. The latent image is visualized with toner, and then the toner image is transferred onto a recording medium such as a recording sheet to form an image.

  Here, a scanning device that emits a light beam to expose and scan the surface of the photosensitive member needs to accurately assemble the light beam emission position, the position of the polygon mirror, and the position of the scanning optical system that guides the light beam to the photosensitive member. Therefore, it is often manufactured as a scanning unit in which each of the above parts is mounted in a frame molded from resin.

  On the other hand, for users who use printers in ordinary homes, it is convenient if the printer can be installed in a not-so-large space such as on a desk. Therefore, there is a strong demand for downsizing an image forming apparatus such as a laser printer. Here, if the lens constituting the scanning optical system is made thin in order to reduce the size of the scanning unit, it is necessary to adjust the position of the emitted light beam with higher accuracy.

  An example of a method for adjusting the position of a light beam (particularly the position in the sub-scanning direction orthogonal to the scanning direction by a deflector such as a polygon mirror) is disclosed in Patent Document 1.

JP 2001-108922 A

  The technique described in Patent Document 1 includes a vertical shaft provided with a rack below an LD unit on which a laser diode is mounted, and meshes the gear at the front end of the motor with the rack to control the amount of rotation of the motor. The position of the LD unit in the sub-scanning direction is controlled.

  However, there is usually some play between the gear and the rack, and this is not always suitable for controlling the position of the light beam in the sub-scanning direction with high precision when the scanning lens is thinned. It has the problem that it cannot be said.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus and a scanning unit that can be further reduced in size through thinning of a scanning lens.

  In order to solve the above-described problems, an image forming apparatus according to the present invention includes a scanning unit that emits a light beam and exposes and scans the surface of the photoreceptor, and the scanning unit emits the light beam. A light source that emits light, a collimator lens that makes the emitted light beam substantially parallel light, a holder equipped with a slit that blocks a part of the parallel light, and a light beam emitted from the light source. A deflector, a cylindrical lens for condensing the light beam that has passed through the slit on a reflective surface of the deflector, and a unit frame having a base portion on which the deflector and the cylindrical lens are mounted. The holder is fixed to the unit frame by being bonded with an adhesive so that a lower end portion of the holder and the surface of the base portion are spaced apart from each other. It is characterized in Rukoto.

  This configuration is characterized in that the position of the holder is fixed by bonding using an adhesive in a state where the lower end of the holder to which a light source or the like is mounted is spaced from the surface of the base portion of the unit frame. . As a result, the position of the light beam can be determined with high accuracy, and it is possible to cope with the thinning of the scanning lens, and it is also possible to cope with the case where the accuracy of the deflector is somewhat lowered due to cost reduction. Become. In addition, it is not necessary to adjust the position at any time as in the technique of Patent Document 1 to cope with the thinning of the scanning lens, and it is only necessary to fix the positional relationship first. There is also an effect that it is not necessary to provide a motor or the like.

  The holder lower end may be provided with a plate-like member having a flat bottom surface of the holder, but the lower end is not necessarily a plate-like member or flat. Also, the bonding position is not particularly limited, and it can be bonded with a space by filling a resin adhesive between the base surface and the holder bottom surface, or can be bonded at a portion other than the bottom surface of the holder. A separate member for adhesion can also be provided.

  As an example of a specific configuration, the holder is configured by a plate-like member having a lower end portion provided with one or more notch grooves at an edge, and the base portion is fitted with the notch groove. It can be set as the structure provided with the protrusion to do. These notch grooves and protrusions are provided for positioning the holder and do not necessarily have to be bonded at this portion. But it is good also as a structure filled with the said adhesive agent in the fitting part of the said protrusion and the said notch groove. It is effective for positioning of the light beam that the protrusions of the base part are provided at two positions on the main plane of the collimator lens, but the position of the protrusions is not limited to this.

  As another example of a specific configuration, the holder includes a pair of extending portions extending in a direction orthogonal to the optical axis of the collimator lens, and the extending portion includes light beams of the collimator lens. Through-holes are provided at positions that are line-symmetric with respect to the axis, and two rod-shaped members are implanted substantially in parallel from the surface of the base portion, and each of the rod-shaped members is the through-hole. The rod-shaped member and the periphery of the through hole may be bonded to each other with an adhesive in a state where the rod-shaped member is inserted into the hole.

  Further, a plate-like member having a flat bottom surface of the holder is disposed at the lower end portion of the holder, the unit frame surface facing the bottom surface is a flat surface, and the holder includes the bottom surface and the If the unit frame surface is bonded so that it is substantially parallel to the unit frame surface, the holder bottom surface and the unit frame surface are first aligned, and then the gap between the two is gradually increased. This is effective in improving the positioning accuracy when a manufacturing method such as adhesive bonding is used.

  The adhesion between the holder and the unit frame is preferably made using a UV curable resin or an instantaneous adhesive. This is because the bonding can be performed very quickly. In order to prevent unnecessary adhesion of the adhesive to the peripheral portion, it is more preferable to use a UV curable resin.

  If the holder is made of a material having a smaller coefficient of thermal expansion than the material constituting the unit frame, the position of the light beam can be prevented from shifting due to heat. Specifically, for example, the holder can be made of metal, and the unit frame can be made of resin.

  The image forming apparatus includes a control board that is electrically connected to the light source and controls driving of the light source, and the control board is mounted at a position different from the holder on the unit frame. If so, the substrate mounted on the holder can be reduced in size, which is effective in reducing the size of the scanning unit.

  The scanning unit according to the present invention includes a light source that emits a light beam and a collimator lens that makes the emitted light beam substantially parallel light in a scanning unit that emits a light beam and exposes and scans an object to be scanned. A holder equipped with a slit for blocking a part of the parallel light, a deflector having a reflecting surface and deflecting a light beam emitted from the light source, and a light beam having passed through the slit A cylindrical lens that collects light on a reflecting surface; and a unit frame having a base portion to which the deflector and the cylindrical lens are mounted. The holder includes a lower end portion of the holder and a surface of the base portion. It is characterized by being fixed to the unit frame by being bonded with an adhesive so as to be spaced apart.

  According to the image forming apparatus and the scanning unit of the present invention, the position of the light beam can be adjusted with high accuracy, and even when the scanning lens is thinned, it is possible to reduce the size of the scanning unit. There is an effect that the entire image forming apparatus can be downsized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(1) Overall Configuration of Laser Printer FIG. 1 is a perspective view showing the appearance of a laser printer 1 as an example of an image forming apparatus.

  The laser printer 1 in FIG. 1 includes a housing 2 having a top cover 18 as an upper surface and four side surfaces 2a, 2b, 2c, and 2d (the side surfaces 2c and 2d are in a position that cannot be seen in FIG. 1). The top cover 18 is recessed inward of the housing 2 to form a sheet discharge tray 72. A paper feed cassette 6 capable of storing a plurality of recording media such as recording paper is provided at the lower portion of the housing 2 so as to be freely inserted and removed from the front side surface 2 a of the housing 2. The front side surface 2a is provided with a manual tray portion 11 for individually setting recording media, and a front cover 16 that can be opened and closed.

  As indicated by phantom lines in FIG. 1, a pair of side frames 190b and 190d are provided inside the opposing side surface 2b and side surface 2d, respectively, and an iron plate or the like is provided below the top cover 18 on the top surface of the housing 2. A rigid plate 190 is constructed between the side frames 190b and 190d. The side frames 190b and 190d are molded from an iron plate or a resin such as polystyrene or ABS. A scanning unit (not shown) is fixed below the rigid plate 190.

Hereinafter, the configuration of the laser printer 1 will be described in more detail with reference to FIG.
FIG. 2 is a schematic sectional side view of the laser printer 1 as viewed from the side surface 2d.
The laser printer 1 includes a recording paper or the like as a recording medium in a housing 2 provided with a top cover 18 on the top surface, a front cover 16 provided on the front side surface 2a, a rear cover 60 provided on the back side surface 2c, and the like ( In the drawing, a recording medium conveyance path is represented by a virtual line P.) A sheet feeding unit 3 for feeding a sheet) and a process cartridge 4 for forming a visible toner image on the fed recording medium. A fixing unit 5 for fixing the toner image formed on the recording medium onto the recording medium, a paper discharge unit 70 for discharging the recording medium that has passed through the fixing unit 5, and the like. In the present specification, of the four side surfaces 2a to 2d of the housing 2, the side surface on the side where the front cover 16 is provided (the right side surface in FIG. 2) among the front and rear surfaces in the recording medium conveyance direction is the front side. The side surface 2a and the opposite side are the back side surface 2c.

  The paper feed unit 3 includes a paper feed cassette 6 and paper feed rollers 7 and 8 provided above the front end (front side) end of the recording medium stacked in the paper feed cassette 6 in the sheet conveying direction. Including pad 9. The paper feed unit 3 is formed with a paper feed path 10 which is a recording medium transport path for inverting the recording medium fed from the paper feed cassette 6 and transporting it to the lower part of the process cartridge 4. 3 includes a registration roller pair 12 facing the paper feed path 10. In addition to the recording medium in the paper feeding cassette 6, a recording medium (recording paper or the like) manually set on the manual feed tray unit 11 is also fed into the paper feeding path 10. After stopping at the registration roller pair 12, the toner is supplied to the image forming unit of the process cartridge 4 in accordance with the image forming timing in the process cartridge 4.

  The paper feed cassette 6 is disposed below the process cartridge 4 and the fixing unit 5 and is mounted so as to be insertable / removable from the front side surface 2 a of the housing 2. A paper pressing plate 13 and a spring 14 are provided in the paper feeding cassette 6. The sheet pressing plate 13 is capable of stacking recording media in a stacked form, and is supported so as to be swingable at the end far from the paper feed roller 7 and the like, so that the near end can move in the vertical direction. It is said that. The spring 14 is provided so as to urge the back surface of the end of the paper pressing plate 13 closer to the paper feed roller 7 and the like upward. Therefore, the sheet pressing plate 13 is swung downward against the urging force of the spring 14 with the end farther from the sheet feed roller 7 and the like as a fulcrum as the amount of recording medium stacked increases.

  The paper feed roller 8 and the paper feed pad 9 are disposed to face each other, and the paper feed pad 9 is pressed toward the paper feed roller 8 by a spring 15 provided on the back side of the paper feed pad 9. The uppermost recording medium stacked on the paper pressing plate 13 is pressed against the paper feed roller 7 by a spring 14 from the back side of the paper pressing plate 13, and the uppermost recording medium is fed. After being fed by the paper roller 7 and sandwiched between the paper feed roller 8 and the paper feed pad 9, the paper feed roller 8 is rotated and separated by the paper feed roller 8 and the paper feed pad 9 one by one. However, the paper is fed toward the paper feed path 10.

  The recording medium fed from the paper feed cassette 6 or the manual feed tray unit 11 is sent to a pair of registration rollers 12 arranged above the paper feed roller 7 and the like. The registration roller pair 12 conveys the fed recording medium to the image forming position (contact position between the photosensitive drum 37 and the transfer roller 39) in the process cartridge 4 after registration. A front cover 16 is provided on the front side surface 2 a of the housing 2. The front cover 16 is provided so as to be openable and closable with respect to the housing 2. The process cartridge 4 can be inserted and removed through an opening that appears when the front cover 16 is opened.

  The scanning unit 100 provided on the upper part of the process cartridge 4 is a polygon as a deflector which is driven to rotate at high speed by a laser diode 271 (see FIG. 3) for emitting a laser beam and is rotated at high speed by a polygon motor 112 (see FIG. 4). The mirror 110, the laser beam is condensed in the scanning direction (main scanning direction) by the polygon mirror 110, and the fθ lens (first scanning lens) 120 that makes the scanning speed on the photosensitive drum 37 constant is the main laser beam. A cylindrical lens (second scanning lens) 140 that condenses light in the sub-scanning direction (rotating direction of the photosensitive drum 37) orthogonal to the scanning direction, a first folding mirror 130, a second folding mirror 131, and the like are provided.

  The laser beam modulated based on the image information and emitted from the laser diode 271 is a polygon mirror 110, an fθ lens 120, a first folding mirror 130, a cylindrical lens 140, and a second folding mirror 131, as indicated by a one-dot chain line. Then, the surface of the photosensitive drum 37 in the process cartridge 4 is exposed and scanned.

  Side frames 190b and 190d (in the figure, a rigid plate (iron plate in the present embodiment) 190 constituting the upper surface of the housing 2 on the lower inner side of the top cover 18 respectively constitute the side surface 2b and the side surface 2d of the housing 2. 1), and the rigid plate 190 also serves as the upper lid of the scanning unit 100.

  The process cartridge 4 includes a drum cartridge 35 and a developing cartridge 36. The drum cartridge 35 includes a photosensitive drum 37, a charger 38, a transfer roller 39, and the like. As described above, the process cartridge 4 is detachable inside the housing 2 from the opening when the front cover 16 is opened. The developing cartridge 36 is detachably attached to the drum cartridge 35, and includes a developing roller 40, a layer thickness regulating blade 41, a supply roller 42, a toner hopper 43, and the like.

  The toner in the toner hopper 43 is agitated by the rotation of the agitator 45 supported by the rotating shaft 44 in the direction of the arrow, and is discharged from the toner supply port 46 opened at the side of the toner hopper 43. The supply roller 42 is rotatably disposed at a side position of the toner supply port 46, and the developing roller 40 is rotatably disposed so as to face the supply roller 42. The supply roller 42 and the developing roller 40 are in contact with each other in a state where each of them is compressed to some extent.

  The developing roller 40 has a metal roller shaft covered with a roller made of a conductive rubber material, and is driven to rotate in the direction of the arrow (counterclockwise). The developing roller 40 is configured to be applied with a developing bias. A layer thickness regulating blade 41 is disposed in the vicinity of the developing roller 40. This layer thickness regulating blade 41 is provided with a pressing portion having a semicircular cross section made of insulating silicone rubber at the tip of a blade body made of a metal leaf spring material. The pressing portion is configured to be pressed against the developing roller 40 by the elastic force of the blade body.

  The toner discharged from the toner supply port 46 is supplied to the developing roller 40 by the rotation of the supplying roller 42. At this time, the toner is positively frictionally charged between the supplying roller 42 and the developing roller 40. The toner supplied above enters between the pressing portion of the layer thickness regulating blade 41 and the developing roller 40 as the developing roller 40 rotates, and is carried on the developing roller 40 as a thin layer having a constant thickness. The

  The photosensitive drum 37 is supported by the drum cartridge 35 so as to be rotatable in the arrow direction (clockwise) in a state facing the developing roller 40 at a side position of the developing roller 40. The photoreceptor drum 37 is formed of a positively chargeable photosensitive layer whose drum body is grounded and whose surface is made of polycarbonate or the like.

  The charger 38 is disposed to face the photosensitive drum 37 in the diagonally left direction with a predetermined interval. The charger 38 is a scorotron charger for positive charging that generates corona discharge from a charging wire such as tungsten, and is configured to uniformly charge the surface of the photosensitive drum 37 to a positive polarity. Yes.

  The transfer roller 39 is disposed below the photoconductive drum 37 so as to face the photoconductive drum 37 and is supported by the drum cartridge 35 so as to be rotatable in an arrow direction (counterclockwise). The transfer roller 39 is configured such that a metal roller shaft is covered with a roller made of a conductive rubber material, and a transfer bias is applied during transfer.

  As the photosensitive drum 37 rotates, the surface of the photosensitive drum 37 is first uniformly charged to a positive polarity by the charger 38. Next, an electrostatic latent image is formed by exposure with a laser beam from the scanning unit 100. After that, when the toner which is opposed to the developing roller 40 and is positively charged and held on the developing roller 40 comes into contact with the photosensitive drum 37, the developing bias applied to the developing roller 40 causes the photosensitive drum The electrostatic latent image formed on the surface of the photoconductor 37, that is, the surface of the photoconductive drum 37 that is uniformly positively charged, is supplied to the exposed portion of the surface exposed to the laser beam and lowered in potential. A toner image is formed by being carried on (reversal development).

Thereafter, the toner image carried on the surface of the photosensitive drum 37 is transferred to the recording medium by a transfer bias applied to the transfer roller 39 while the recording medium passes between the photosensitive drum 37 and the transfer roller 39. Transcribed.
The fixing unit 5 is disposed on the upper side of the paper feed cassette 6 and on the side of the process cartridge 4 and on the downstream side of the process cartridge 4 in the recording medium conveyance direction. The fixing unit 5 includes, as a fixing roller, a heating roller 51 provided with a heater therein, and a pressure roller 52 provided to face the heating roller 51 and urged so as to press the heating roller.

  In the fixing unit 5, the toner image, which is a visible image transferred onto the recording medium in the process cartridge 4, is thermally fixed while the recording medium passes between the heating roller 51 and the pressure roller 52. Thereafter, the recording medium is sent to a paper discharge path 76 that is a recording medium conveyance path formed in the paper discharge unit 70.

  The paper discharge unit 70 includes an inner guide member 71 and an outer guide member 62 that constitute a paper discharge path 76, and a paper discharge roller provided at a discharge port for discharging the recording medium onto a sheet discharge tray 72 provided on the top cover 18. The pair includes a tray member 74 having a lower discharge roller 73, an upper discharge roller 75, and a portion constituting a part of the sheet discharge tray 72.

  The outer guide member 62 constituting the paper discharge path 76 is configured to swing to the back side in conjunction with opening and closing of the rear cover 60 provided on the back side surface 2 c of the housing 2, and via the hinge 61. When the rear cover 60 attached so as to be swingable is opened, the upper portion of the outer guide member 62 swings to the back side in conjunction with the opening. In this way, the discharge path 76 is configured to face the opening formed in the rear side surface 2c of the housing 2 when the rear cover 60 is opened.

  The sheet discharge tray 72 has a substantially rectangular plate shape in plan view, and a rear end portion is recessed into the housing 2 to form a recess, and is gradually inclined upward from the rear end portion toward the front side. It is the composition to do. The sheet discharge tray 72 is configured by a tray member 74 from the rear side end portion to the middle portion gradually inclined upward, and the upper surface of the front end side (front end side in the recording medium conveyance direction) of the tray member 74 is The top cover 18 is configured to come into contact with the lower surface of the end portion on the tray member 74 side.

  The recording medium that has passed through the fixing unit 5 and is sent to the paper discharge path 76 is sent to the paper discharge roller pair with the paper traveling direction being reversed in the upward direction by the inner guide member 71 and the outer guide member 62. The sheet is discharged onto the sheet discharge tray 72 toward the front side via the pair of discharge rollers (73 and 75). The rigid plate 190 is installed directly below a portion formed by the top cover 18 of the sheet discharge tray 72.

(2) Detailed Configuration of Scanning Unit 100 Next, the configuration of the scanning unit 100 of the present embodiment will be described in detail.
FIG. 3 is a top view for explaining the configuration of the scanning unit 100, and FIG. 4 is a schematic sectional view.

  The scanning unit 100 has an opening 223 through which a laser beam passes from the side on which the first folding mirror 130 is mounted (front surface side) to the side on which the second folding mirror 131 is mounted (back surface side). And a unit frame 200 including a flat base portion 220 to which each portion such as the fθ lens 120 is mounted, and an outer peripheral portion 210 that constitutes an outer peripheral wall surrounding a lateral outer periphery of the base portion 220 (FIG. 3). ). The unit frame 200 can be manufactured, for example, by integrally forming a resin containing glass fiber by injection molding.

  An opening 222 is provided in a portion of the base 220 where a polygon motor 112 (FIG. 4) for rotating the polygon mirror 110 is mounted (FIG. 3), and a substrate 260 on which the polygon motor 112 is mounted is below the opening 222. The scanning unit 100 is thinned by being fastened with screws 261 and 262 (FIG. 4).

  The base 220 is further provided on the substrate 271a, and a laser diode 271 that emits a laser beam, a collimator lens 272 that collimates the emitted laser beam into parallel light, and a part of the parallel light is shielded and shaped. An LD holder 270 to which a slit plate 273 having a slit is attached is mounted (FIG. 3). In this embodiment, the LD holder 270 is manufactured by processing a metal such as an iron plate, but this material is not particularly limited. However, it is preferable that the LD holder 270 is formed of a material having a smaller thermal expansion coefficient than that of the material constituting the unit frame 200 including the base portion 220, from the viewpoint that the displacement of the laser beam due to heat can be suppressed.

  The LD control board 275 for controlling the driving of the laser diode 271 is mounted on a board mounting part 225 provided in the outer peripheral part 210 so as to protrude upward from the base part 220 along the outer peripheral wall. 271 is connected to a substrate 271a on which the 271 is mounted (FIG. 3). Thus, by providing the substrate 271a on which the laser diode 271 is mounted and the LD control substrate 275 for controlling the driving of the laser diode 271 as separate bodies, it is not necessary to enlarge the substrate 271a, which is effective for downsizing the scanning unit. is there. The board mounting part 225 is integrally formed with the base part 220 by injection molding.

  The laser beam emitted from the laser diode 271 and passing through the slit plate 273 is condensed by the cylindrical lens 274 in the sub-scanning direction orthogonal to the scanning direction by the polygon mirror 110 and reaches the reflection surface of the polygon mirror 110 (inconvenient). For correction). The laser beam that has reached the reflecting surface is deflected by the polygon mirror 110 that is driven to rotate at high speed, passes through the fθ lens 120 while diverging again, is reflected by the first folding mirror 130, and is reflected by the base 220 through the opening 223. Head down (back side). Thereafter, the laser beam passes through the cylindrical lens 140, is reflected by the second folding mirror 131, passes through the glass plate 252 attached to the opening provided in the lower cover 250 of the scanning unit 100, and the surface of the photosensitive drum 37. Is exposed and scanned (FIG. 4).

  In this embodiment, in order to make the scanning unit 100 thinner, the thickness of the cylindrical lens 140 in the sub-scanning direction is reduced to about 6 mm, and in order to ensure that the laser beam passes through the cylindrical lens 140, It is necessary to control the position of the light beam with higher accuracy. This is because when the position of the laser beam is deviated in the sub-scanning direction, the laser beam passing position may be out of the effective area of the cylindrical lens 140.

Therefore, in the scanning unit 100 according to the present embodiment, the position of the laser beam is adjusted with high accuracy by bonding and fixing the LD holder 270 with an adhesive while the lower end of the LD holder 270 is lifted from the base 220. I am going to do it.
FIG. 5 is a top view showing the configuration of the portion where the LD holder 270 is mounted on the base 220 (the enlarged view of FIG. 3, the adhesive is not shown in FIGS. 3 and 5), FIG. 6A is a perspective view showing the portion of the base 220, and FIG. 6B is a cross-sectional view of the state where the holder 270 is bonded with an adhesive from the direction of arrow A in FIG. (Not shown). FIG. 7 is a perspective view for explaining a state when the LD holder 270 is mounted on the base part 220.

  In the present embodiment, protrusions 279a to 279d are provided at four locations on the base portion 220 side (FIGS. 5 and 6A). On the other hand, the LD holder 270 is provided with notches 278a to 278d (FIGS. 5 and 7). Then, with the lower end portion of the LD holder 270 (in this embodiment, the bottom surface of the LD holder 270) floating from the base portion 220, the cutout grooves 278a to 278d are fitted into the projections 279a to 279d, respectively, and are ejected. While monitoring the state of the laser beam, the vertical position of the LD holder 270 is adjusted. The position adjustment of the LD holder 270 is preferably performed using an apparatus that supports the LD holder 270 and can adjust the position in the vertical direction. Note that the position adjustment itself may be performed manually.

  Then, when the laser beam passes through an appropriate position, the positional relationship between the two is fixed by bonding the LD holder 270 and the base 220 using an adhesive. In this embodiment, the protrusion 279b and the notch groove 278b are used exclusively for positioning, and UV is formed at the boundary portions formed between the notch grooves 278a, 278c, 278d and the protrusions 279a, 279c, 279d, respectively. Adhesion is performed by filling the cured resin and curing the UV cured resin with ultraviolet rays when the position adjustment is completed.

  As shown in FIG. 6B, the adhesive 281c is filled between the notch groove 278c and the protrusion 279c, and the adhesive 281a is filled between the notch groove 278a and the protrusion 279a. (This also applies between the notch groove 278d and the protrusion 279d.) The holder 270 is fixed to the unit frame 200 in a state where the lower end portion of the holder 270 and the base portion 220 are spaced apart.

  The adhesive is not limited to the UV curable resin, and an instantaneous adhesive can also be used. These are preferable in that they can be fixed by bonding very quickly, but are not limited thereto. In order to prevent the adhesive from adhering to the periphery, it is preferable to use a UV curable resin.

  The bonding with the adhesive does not necessarily have to be performed at the boundary portion between the notch groove 278a and the projection 279a and the like, and can be performed at another portion. Depending on the material of the LD holder 270, the LD holder 270 may be used. A method of filling a resin adhesive between the bottom surface of the base plate and the surface of the base portion 220 is also possible. Even in this case, providing the projections 279a and the like and the cutout grooves 278a and the like is suitable for positioning the LD holder 270 in the horizontal direction. Of course, the notch groove 278b and the protrusion 279b may be bonded.

  In this embodiment, the position adjustment of the laser beam is performed in a state where the LD holder 270 and the LD control board 275 are connected by the harness 276. Therefore, the protrusions 279a to 279d and the cutouts are provided for the convenience of bonding. Although the grooves 278a to 278d are provided at positions as shown in the drawing, these positions are not particularly limited. Of course, in order to control the position of the laser beam with higher accuracy, it is effective to provide it at two locations on the main plane of the collimator lens 272.

  In the present embodiment, a plate-like member having a flat bottom surface of the LD holder 270 is used as the lower end portion of the LD holder 270, and the surface of the base portion 220 facing the bottom surface is flat. By adopting such a shape, the LD holder 270 can be temporarily placed on the surface of the base portion 220, and thereafter, the position of the LD holder 270 can be gradually raised to adjust the position. This is suitable for preventing the LD holder 270 from being inclined. However, in order to bond the LD holder 270 in a state where the lower end portion of the LD holder 270 floats from the surface of the base portion 220, the lower end portion is not necessarily the bottom surface.

  As described above, in the scanning unit of the present embodiment, the position of the LD holder 270 is adjusted by bonding the lower end of the LD holder 270 with the adhesive with the base 220 being spaced apart from the base 220. Since the position is fixed, the position of the laser beam emitted with higher accuracy can be adjusted, and the image forming apparatus can be downsized through the thinning of the scanning lens. It should be noted that adjusting the position using an adhesive is also effective for dealing with a case where the accuracy of a deflector such as a polygon mirror is somewhat lowered for cost reduction. This is because it is possible to perform adjustment so that the laser beam does not deviate from the effective area of the scanning lens even when the surface of the deflector is large.

(Modification)
Although the embodiments of the present invention have been described above, the contents of the present invention are not limited to the specific examples described in the above embodiments. For example, the following modifications may be implemented. it can.

  (1) In the above embodiment, the base portion 220 is provided with the protrusions 279a to 279d, and the protrusions 279a to 279d and the notch grooves 278a to 278d provided in the LD holder 270 are fitted. However, the structure for adjusting the position of the LD holder is not limited to the protrusion and the notch groove as described above.

  For example, as shown in FIG. 8, two rod-like members 279e and 279f are implanted in the base 220 substantially in parallel, and are mounted on an LD holder 270a (laser diode, slit plate, etc. are not shown). A pair of extending portions 280e and 280f may be extended on both the left and right sides of the collimator lens 272, and the through holes 278e and 278f may be provided at positions that are line-symmetric with respect to the optical axis of the collimator lens 272, respectively.

  In this configuration, the rod-shaped members 279e and 279f and the through-holes 278e and 278f are bonded to each other with an adhesive in a state where the rod-shaped members 279e and 279f are inserted into the through-holes 278e and 278f, respectively. The position of the laser beam can be adjusted in the same manner as in the case of providing the above. Also in this case, the number of rod-shaped members is arbitrary and two or more may be provided. In addition, although it is suitable for position adjustment if the through holes are provided on both sides of the collimator lens 272 (positions that are line-symmetric with respect to the optical axis), the position of the through holes is not necessarily limited thereto.

  (2) In the above embodiment, the LD holder and the base 220 are bonded to fix the positional relationship between the LD holder and the unit frame, but the bonding position is completely arbitrary, You may make it adhere | attach between, and you may make it project the member for adhesion | attachment from the outer peripheral part 210. FIG.

  (3) In the above embodiment, the laser beam reflected by the first folding mirror 130 is directly incident on the second folding mirror 131 provided on the back side of the base unit 220. Such an optical path is suitable for reducing the size of the scanning unit 100, but a configuration may be adopted in which a folding mirror is further provided between the first folding mirror 130 and the second folding mirror 131.

  (4) In the above embodiment, the opening 222 is provided at the installation position of the polygon mirror 110 and the polygon motor 112 in the base 220, and the substrate 260 on which the polygon motor 112 is mounted is fastened from the back side of the base 220. The configuration. This configuration is suitable for reducing the thickness of the scanning unit 100, but the opening 222 may not be provided, and a substrate on which the polygon motor 112 is mounted may be provided on the surface side of the base unit 220.

  (5) In the above embodiment, the polygon mirror 110 and the polygon motor 112 are used as deflectors for deflecting the laser beam. However, the present invention is not limited to this. For example, a galvanometer mirror or the like can be used as the deflector. In such a case, the first scanning lens is not limited to the fθ lens 120, and a lens having other optical characteristics may be used.

  The present invention can be applied to, for example, an image forming apparatus including a scanning unit that emits a light beam and scans an object to be scanned such as a photosensitive member, and a scanning unit.

1 is a perspective view illustrating an appearance of a laser printer as an example of an image forming apparatus to which the present invention is applied. 1 is a schematic sectional side view of a laser printer 1. FIG. 4 is a top view for explaining the configuration of the scanning unit 100. FIG. 2 is a schematic sectional view of a scanning unit 100. FIG. FIG. 6 is a top view showing a configuration of a portion where the LD holder 270 is mounted in the base part 220. (A) It is a perspective view which shows the LD holder 270 mounting part of the base part 220. FIG. (B) It is sectional drawing which looked at the state where the holder 270 was adhere | attached with the adhesive agent from the arrow A direction of Fig.6 (a). It is a perspective view for demonstrating a mode at the time of mounting | wearing the LD holder 270 to the base part 220. FIG. It is a perspective view for demonstrating mounting | wearing of the LD holder 270 to the base part 220 in the modification of this invention.

Explanation of symbols

16 Front cover 18 Top cover 37 Photosensitive drum 72 Sheet discharge tray 100 Scan unit 110 Polygon mirror 112 Polygon motor 120 fθ lens 130 First folding mirror 131 Second folding mirror 140 Cylindrical lens 190 Rigid plate 190b, 190d Side frame 200 Unit frame 210 Peripheral part 220 Base part 222, 223 Opening 225 Substrate mounting part 250 Back cover 260 Substrate 270, 270a LD holder 271 Laser diode 271a Substrate 272 Collimator lens 273 Slit plate 274 Cylindrical lens 275 LD control base 276 Harness 278a-278d Notch Groove 278e, 289e Through hole 279a-279d Protrusion 279e, 279f Bar-shaped member 280 , 280F extending portions 281a, 281c adhesives (UV curable resin)

Claims (11)

In an image forming apparatus including a scanning unit that emits a light beam and exposes and scans the surface of a photoreceptor.
The scanning unit is
A holder equipped with a light source that emits a light beam, a collimator lens that makes the emitted light beam substantially parallel light, and a slit that blocks part of the parallel light;
A deflector having a reflecting surface and deflecting the light beam emitted from the light source;
A cylindrical lens for condensing the light beam that has passed through the slit on the reflecting surface of the deflector;
A unit frame having a base on which the deflector and the cylindrical lens are mounted;
The image forming apparatus, wherein the holder is fixed to the unit frame by being bonded with an adhesive so that a lower end portion of the holder and a surface of the base portion are spaced apart from each other. The holder is
The lower end portion is constituted by a plate-like member provided with one or more notch grooves at the edge,
The base is
The image forming apparatus according to claim 1, further comprising a protrusion that fits into the notch groove. The image forming apparatus according to claim 2, wherein the adhesive is filled in a fitting portion between the protrusion and the notch groove. The protrusion of the base part is
The image forming apparatus according to claim 2, wherein the image forming apparatus is provided at two locations on a main plane of the collimator lens. The holder is
A pair of extending portions each extending in a direction perpendicular to the optical axis of the collimator lens is provided, and each of the extending portions has a through hole at a position that is line-symmetric with respect to the optical axis of the collimator lens. Provided,
Two rod-shaped members are implanted substantially in parallel from the surface of the base part,
2. The image forming apparatus according to claim 1, wherein the rod-shaped member and the periphery of the through-hole are bonded with an adhesive in a state where each of the rod-shaped member is inserted into the through-hole. A plate-like member is disposed at the lower end of the holder such that the bottom surface of the holder is a plane,
The base portion surface facing the bottom surface is a plane,
The holder is
The image forming apparatus according to claim 1, wherein the image forming apparatus is fixed so that the bottom surface and the base portion surface are substantially parallel to each other. The adhesive is
The image forming apparatus according to claim 1, wherein the image forming apparatus is a UV curable resin or an instantaneous adhesive. The image forming apparatus according to claim 1, wherein the holder is made of a material having a smaller coefficient of thermal expansion than a material constituting the unit frame. The image forming apparatus according to claim 8, wherein the holder is made of metal, and the unit frame is made of resin. The image forming apparatus includes:
A control board that is electrically connected to the light source and controls driving of the light source;
The control board is
The image forming apparatus according to claim 1, wherein the image forming apparatus is mounted at a position different from the holder on the unit frame. In a scanning unit that emits a light beam and exposes and scans an object to be scanned,
A holder equipped with a light source that emits a light beam, a collimator lens that makes the emitted light beam substantially parallel light, and a slit that blocks part of the parallel light;
A deflector having a reflecting surface and deflecting the light beam emitted from the light source;
A cylindrical lens for condensing the light beam that has passed through the slit on the reflecting surface of the deflector;
A unit frame having a base on which the deflector and the cylindrical lens are mounted;
The scanning unit, wherein the holder is fixed to the unit frame by being bonded with an adhesive so that a lower end portion of the holder and a surface of the base portion are spaced apart from each other.

Images