JP2024049733A - Optical scanning device and image forming device - Google Patents

Abstract

[Problem] To provide an optical scanning device that can be made smaller by reducing the number of parts, and an image forming apparatus equipped with the same. [Solution] The optical scanning device has a light source unit, a deflector, a first scanning lens, a second scanning lens, and a pair of reflecting mirrors. The first scanning lens focuses the light beam reflected by the deflector. The second scanning lens forms an image of the light beam that has passed through the first scanning lens on the peripheral surface of an image carrier. The pair of reflecting mirrors reflect the light beam that has passed through the second scanning lens toward the image carrier on the imaging optical path. The light beam reflected by the pair of reflecting mirrors passes between the first scanning lens and the second scanning lens toward the image carrier. [Selected Figure] Figure 5

Description

The present invention relates to an optical scanning device and an image forming device.

A conventional optical scanning device is disclosed in Patent Document 1. This optical scanning device has a light source unit, a deflector, a first scanning lens, a second scanning lens, and multiple reflecting mirrors. The light source unit has multiple light-emitting modules that emit light beams arranged in the sub-scanning direction. The deflector rotates around an axis to reflect the light beam emitted from the light source unit and scan the peripheral surface of the image carrier in the main scanning direction. The first scanning lens focuses the light beam reflected by the deflector. The second scanning lens images the light beam that has passed through the first scanning lens on the peripheral surface of the image carrier. The reflecting mirror reflects the light beam that has passed through the second scanning lens toward the image carrier on the imaging optical path.

JP 2009-098332 A

The conventional optical scanning device described above had a problem in that the optical path of the light beam that passed through the second scanning lens was extended, making the entire optical scanning device larger.

In order to achieve the above objective, the present invention aims to provide a compact optical scanning device and an image forming device equipped with the same.

In order to achieve the above object, the optical scanning device of the first configuration of the present invention has a light source unit, a deflector, a first scanning lens, a second scanning lens, and a pair of reflecting mirrors. The light source unit has a plurality of light emitting modules that emit light beams arranged in the sub-scanning direction. The deflector rotates around an axis to reflect the light beam emitted from the light source unit and scans the peripheral surface of the image carrier in the main scanning direction. The first scanning lens focuses the light beam reflected by the deflector. The second scanning lens forms an image of the light beam that has passed through the first scanning lens on the peripheral surface of the image carrier. The pair of reflecting mirrors reflect the light beam that has passed through the second scanning lens toward the image carrier on the imaging optical path. The light beam reflected by the pair of reflecting mirrors passes between the first scanning lens and the second scanning lens toward the image carrier.

The first aspect of the present invention provides a compact optical scanning device and an image forming device equipped with the same.

FIG. 1 is a cross-sectional view showing a schematic overall configuration of an image forming apparatus 1 in which an optical scanning device 12 according to the present invention is mounted. FIG. 1 is a perspective view of an optical scanning device 12 according to an embodiment of the present invention; FIG. 1 is a perspective view showing a part of an optical scanning device 12 according to an embodiment of the present invention. FIG. 1 is a cross-sectional view showing a part of an optical scanning device 12 according to an embodiment of the present invention. 1 is a diagram showing an optical path of an optical scanning device 12 according to an embodiment of the present invention; FIG. 1 is a perspective view of a second scanning lens 124 a of the optical scanning device 12 according to an embodiment of the present invention. FIG. 1 is a perspective view of a second scanning lens 124 a of the optical scanning device 12 according to an embodiment of the present invention. 1 is a cross-sectional view of a second scanning lens 124a of the optical scanning device 12 according to an embodiment of the present invention.

Below, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic overall configuration of an image forming apparatus 1 in which an optical scanning device of the present invention is mounted. For ease of explanation, the vertical direction in an installed state (as shown in FIG. 1) in which the image forming apparatus 1 can be used is defined as the up-down direction (Z1-Z2 direction). In addition, the front side of the paper of the image forming apparatus 10 shown in FIG. 1 is defined as the front (front face), and the front-rear direction (Y1-Y2 direction) is defined. In addition, the left-right direction (X1-X2 direction) is defined with the front face of the image forming apparatus 10 in the installed state as the reference point.

The image forming device 1 is a tandem type color printer. The image forming device 1 is equipped with rotatable photoconductor drums 11a to 11d as image carriers. For the photoconductor drums 11a to 11d, an organic photoconductor (OPC photoconductor) having an organic photosensitive layer formed thereon, or an amorphous silicon photoconductor having an amorphous silicon photosensitive layer formed thereon, or the like, is used. The photoconductor drums 11a to 11d are arranged in tandem to correspond to the respective colors of yellow, cyan, magenta, and black.

Around the photoconductor drum 11a, there are arranged a developing device 2a, a charger 13a, and a cleaning device 14a. Similarly, around the photoconductor drums 11b to 11d, there are arranged developing devices 2b to 2d, chargers 13b to 13d, and cleaning devices 14b to 14d, respectively. In addition, there is an optical scanning device 12 below the developing devices 2a to 2d.

The developing devices 2a to 2d are disposed on the left side X2 of the photoconductor drums 11a to 11d, respectively. The developing devices 2a to 2d face the photoconductor drums 11a to 11d, respectively, and supply toner to the photoconductor drums 11a to 11d. In this specification, right and left refer to the right and left in the drawings.

The chargers 13a to 13d are disposed upstream of the developing devices 2a to 2d in the direction of rotation of the photoconductor drums 11a to 11d, and face the surfaces of the photoconductor drums 11a to 11d, respectively. The chargers 13a to 13d uniformly charge the surfaces of the photoconductor drums 11a to 11d, respectively.

In this embodiment, the optical scanning device 12 is disposed on the upper side Z1 of the photoconductor drums 11a to 11d. The optical scanning device 12 irradiates light (optical scanning) onto the surfaces of the photoconductor drums 11a to 11d, which have been uniformly charged by the chargers 13b to 13d, based on image data such as characters and pictures input to an image input unit from a personal computer or the like. This forms an electrostatic latent image on the surfaces of the photoconductor drums 11a to 11d.

The housing 12a of the optical scanning device 12 includes a storage section 12b with one surface (the bottom surface in this embodiment) open, and a cover section 12c that covers the opening. The storage section 12b incorporates the scanning optical system 120 inside. The cover section 12c has exit ports for the light beams B1 to B4 emitted from the scanning optical system 120 corresponding to the photoconductor drums 11a to 11d (see FIG. 5).

Light beams B1 to B4 are irradiated onto the surfaces of photoconductor drums 11a to 11d from downstream of chargers 13a to 13d in the direction of rotation of photoconductor drums 11a to 11d, respectively. As a result, electrostatic latent images are formed on the surfaces of photoconductor drums 11a to 11d. These electrostatic latent images are developed into toner images by developing devices 2a to 2d. The optical scanning device 12 will be described in detail later.

The endless intermediate transfer belt 17 is stretched around a tension roller 6, a drive roller 25, and a driven roller 27. When the drive roller 25 is rotated by a motor (not shown), the intermediate transfer belt 17 is driven to circulate in the clockwise direction in FIG. 1.

The photoconductor drums 11a to 11d are arranged adjacent to each other along the transport direction (the direction of the arrow in FIG. 1) above the intermediate transfer belt 17, Z1. In addition, the photoconductor drums 11a to 11d are each in contact with the intermediate transfer belt 17.

The primary transfer rollers 26a to 26d face the photoconductor drums 11a to 11d, respectively, with the intermediate transfer belt 17 in between. The primary transfer rollers 26a to 26d are each pressed against the intermediate transfer belt 17, forming a primary transfer section together with the photoconductor drums 11a to 11d. In these primary transfer sections, the toner image is transferred to the intermediate transfer belt 17.

In more detail, a primary transfer voltage is applied to primary transfer rollers 26a-26d, and the toner images on photoconductor drums 11a-11d are transferred sequentially to intermediate transfer belt 17 at a predetermined timing. As a result, a full-color toner image is formed on the surface of intermediate transfer belt 17, in which toner images of four colors, magenta, cyan, yellow, and black, are superimposed in a predetermined positional relationship.

The secondary transfer roller 34 faces the drive roller 25 with the intermediate transfer belt 17 in between. The secondary transfer roller 34 is pressed against the intermediate transfer belt 17 and forms a secondary transfer section together with the drive roller 25. In this secondary transfer section, a secondary transfer voltage is applied to the secondary transfer roller 34, so that the toner image on the surface of the intermediate transfer belt 17 is transferred to the paper P. After the toner image is transferred, the belt cleaning device 31 cleans off any toner remaining on the intermediate transfer belt 17.

A paper feed cassette 32 is disposed at the bottom of the image forming device 1. The paper feed cassette 32 is capable of storing multiple sheets of paper P. A paper transport path 33 is disposed to the right X1 of the paper feed cassette 32.

The paper transport path 33 transports the paper P fed from the paper feed cassette 32 to the secondary transfer section. Also provided within the image forming device 1 are a fixing section 18 and a paper transport path 39. The fixing section 18 performs a fixing process on the paper P on which an image has been formed. The paper transport path 39 transports the paper P after the fixing process to the paper discharge section 37.

The paper P stored in the paper feed cassette 32 is fed one sheet at a time to the paper transport path 33 by the pickup roller 33b and the pair of separating rollers 33a.

The pair of registration rollers 33c transports the paper P to the secondary transfer section in accordance with the timing of the image formation operation on the intermediate transfer belt 17 and the paper feeding operation to the secondary transfer section. The full-color toner image on the intermediate transfer belt 17 is secondarily transferred to the paper P transported to the secondary transfer section by the secondary transfer roller 34 to which a secondary transfer voltage is applied. The paper P to which the full-color toner image has been transferred is transported to the fixing section 18.

The fixing unit 18 includes a fixing belt heated by a heater, a fixing roller in contact with the fixing belt, and a pressure roller pressed against the fixing roller with the fixing belt sandwiched therebetween. The fixing unit 18 heats and presses the paper P onto which the toner image has been transferred. This performs the fixing process. The paper P onto which the toner image has been fixed in the fixing unit 18 is turned over in the paper transport path 40 as necessary. The paper P is then transported again to the secondary transfer unit via the pair of registration rollers 33c, after which a new toner image is secondarily transferred to the rear surface of the paper P by the secondary transfer roller 34, and fixed in the fixing unit 18. The paper P onto which the toner image has been fixed passes through the paper transport path 39 and is discharged to the paper discharge unit 37 by the pair of discharge rollers 19.

Next, the optical scanning device 12 will be described with reference to Figures 2 to 6. Figure 2 is a perspective view of the optical scanning device 12, and Figure 3 is a perspective view showing a part of the optical scanning device 12. Figure 4 is a light path diagram showing the configuration of the optical scanning device 12 in the sub-scanning section. Figure 5 is a light path diagram showing the configuration of the optical scanning device 12 in the sub-scanning section. Note that Figure 5 shows the configuration of each component in a schematic manner, and does not strictly show the shape and positional relationship of each component.

In the following description, the main scanning direction (Y1-Y2 direction) is a direction perpendicular to the rotation axis C of the deflector 122 and the optical axis L of the optical system (see FIG. 5). The main scanning direction (Y1-Y2 direction) coincides with the direction in which the rotation axes of the photoconductor drums 11a to 11d extend and with the front-rear direction of the image forming device 10. The sub-scanning direction (Z1-Z2 direction) is a direction parallel to the rotation axis C of the deflector 122 and coincides with the up-down direction of the image forming device 10. The main scanning section is a section perpendicular to the sub-scanning direction (Z1-Z2 direction), and the sub-scanning section is a section perpendicular to the main scanning direction (Y1-Y2 direction). The left-right direction (X1-X2 direction) is a direction perpendicular to the main scanning direction (Y1-Y2 direction) and the sub-scanning direction (Z1-Z2 direction).

The optical scanning device 12 outputs (irradiates) multiple (four in this embodiment) optical beams B1 to B4 modulated according to each image signal to the photoconductor drums 11a to 11d, forming an electrostatic latent image on each of the photoconductor drums 11a to 11d.

The optical scanning device 12 has a light source unit 121, a deflector 122, first scanning lenses 123a and 123b, second scanning lenses 124a and 124b, and reflecting mirrors 125a, 125b, 126a, 126b, 127a, and 127b.

The light source unit 121 has light-emitting modules 121Y, 121C, 121M, and 121K, a collimator lens 221a, and a cylindrical lens 221b. The collimator lens 221a and the cylindrical lens 221b are integrated. As a result, the light source unit 121 is modularized into an integrated type including the light-emitting modules 121Y, 121C, 121M, and 121K, the collimator lens 221a, and the cylindrical lens 221b.

In this embodiment, the light-emitting modules 121Y and 121C are arranged next to each other in the up-down direction (Z1-Z2 direction) to the right (X1 direction) of the rotation axis C. The light-emitting modules 121M and 121K are arranged next to each other in the up-down direction (Z1-Z2 direction) to the left (X2 direction) of the rotation axis C. Furthermore, the light-emitting module 121C is arranged below the light-emitting module 121Y (Z2 direction). The light-emitting module 121M is arranged below the light-emitting module 121K (Z2 direction).

Each of the multiple light-emitting modules 121Y, 121C, 121M, and 121K outputs light beams B1 to B4 corresponding to the colors Y (yellow), C (cyan), M (magenta), and K (black). The light beams B1 to B4 emitted from each of the light-emitting modules 121Y, 121C, 121M, and 121K pass through a collimator lens 221a and a cylindrical lens 221b and are irradiated onto the deflector 122.

At this time, the collimator lens 221a converts each of the light beams B1 to B4 emitted from the light-emitting modules 121Y, 121C, 121M, and 121K into approximately parallel light in the main scanning cross section. The collimator lens 221a is formed by integrating four regions corresponding to each of the light beams B1 to B4. This allows one collimator lens 221a to handle multiple light beams B1 to B4. The cylindrical lens 221b converges the light beams B1 to B4 in the sub-scanning direction (Z1-Z2 direction) and focuses them near the deflection surface (reflection surface) of the deflector 122. This causes the light beams B1 to B4 to form a line image near the deflection surface of the deflector 122. The cylindrical lens 221b is formed by integrating four regions corresponding to each of the light beams B1 to B4. This allows one cylindrical lens 221b to handle multiple light beams B1 to B4.

When the collimator lens 221a is divided into four regions corresponding to the light beams B1 to B4, and the cylindrical lens 221b is divided into four regions corresponding to the light beams B1 to B4, each divided collimator lens and each divided cylindrical lens may be integrated.

The deflector 122 is a polygon mirror scanner and has a polygon mirror 122a and a scanner motor 122b. The scanner motor 122b rotates the polygon mirror 122a around the axis of rotation C.

The polygon mirror 122a is composed of multiple reflecting surfaces. In this embodiment, the polygon mirror 122a is a polygonal mirror formed in a quadrangular prism shape. The light beams B1 and B2 incident on the polygon mirror 122a are deflected and scanned by an arbitrary reflecting surface that rotates, and are guided to the first scanning lens 123a and the second scanning lens 124a. The light beams B3 and B4 incident on the polygon mirror 122a are deflected and scanned by an arbitrary reflecting surface that rotates, and are guided to the first scanning lens 123b and the second scanning lens 124b.

At this time, the light beams B1 and B4 are incident obliquely from above (Z1 direction) with respect to the normal direction of one of the polarization planes of the polygon mirror 122a, and are emitted obliquely to the lower side (Z2 direction). On the other hand, the light beams B2 and B3 are incident obliquely from below (Z2 direction) with respect to the normal direction of one of the polarization planes of the polygon mirror 122a, and are emitted obliquely to the upper side (Z1 direction).

By rotating the polygon mirror 122a, the light beams B1 to B4 scan the scanned surfaces (circumferential surfaces) of the photoconductor drums (image carriers) 11a to 11d in the main scanning direction (Y1-Y2 direction). In addition, by rotating the photoconductor drums 11a to 11d, the light beams B1 to B4 scan in the sub-scanning direction (Z1-Z2 direction) to form electrostatic latent images on the surfaces of the photoconductor drums 11a to 11d.

Specifically, the light beams B1 and B2 are reflected to the right (X1 direction) by the reflecting surface of the polygon mirror 122a and are guided to the first scanning lens 123a and the second scanning lens 124a. The light beams B3 and B4 are reflected to the left (X2 direction) by the reflecting surface of the polygon mirror 122a and are guided to the first scanning lens 123b and the second scanning lens 124b (see FIG. 5).

The second scanning lenses 124a and 124b are disposed downstream of the first scanning lenses 123a and 123b in the optical paths of the light beams B1 to B4.

The first scanning lenses 123a, 123b and the second scanning lenses 124a, 124b focus the light beams B1 to B4 reflected and deflected by the deflector 122 on the scanned surfaces of the photosensitive drums 11a to 11d, respectively, to form beam spots. In addition, the light beams B1 to B4 focused on the scanned surfaces of the photosensitive drums 11a to 11d scan the scanned surfaces of the photosensitive drums 11a to 11d at a constant speed.

The first scanning lenses 123a and 123b are lenses having distortion aberration (fθ characteristics) and are long lenses extending along the main scanning direction (Y1-Y2 direction). The first scanning lens 123a is disposed to the right (X1 direction) of the polygon mirror 122a. The first scanning lens 123b is disposed to the left (X2 direction) of the polygon mirror 122a. The first scanning lenses 123a and 123b focus the light beams B1 to B4 reflected by the deflection surface of the polygon mirror 122a.

The second scanning lenses 124a and 124b, like the first scanning lenses 123a and 123b, are lenses that have distortion aberration (fθ characteristics) and are long lenses that extend along the main scanning direction (Y1-Y2 direction).

The second scanning lens 124a is disposed to the right (X1 direction) of the first scanning lens 123a. The second scanning lens 124a focuses the light beams B1 and B2 that have passed through the first scanning lens 123a, and forms images on the scanned surfaces of the photosensitive drums 11a and 11b, respectively.

The second scanning lens 124b is disposed to the left (X2 direction) of the first scanning lens 123b. The second scanning lens 124b focuses the light beams B3 and B4 that have passed through the first scanning lens 123b, and forms images on the scanned surfaces of the photoconductor drums 11c and 11d, respectively.

Figures 6 and 7 are perspective views of the second scanning lens 124a, and Figure 6 is a view of the second scanning lens 124a seen from the exit surface 1241 side. Figure 7 is a view of the second scanning lens 124a seen from the entrance surface 1242 side. Figure 8 is a cross-sectional view of the second scanning lens 124a perpendicular to the main scanning direction. The second scanning lens 124b has the same shape as the second scanning lens 124a, and a description thereof will be omitted.

The second scanning lens 124a has a connecting portion 1243 and a rib 1244. The connecting portions 1243 are disposed at both ends of the second scanning lens 124a in the main scanning direction (Y1-Y2 direction) and extend in the sub-main scanning direction (Z1-Z2 direction). The connecting portions 1243 are fixed to the peripheral wall portion of the housing 12a of the optical scanning device 12 (see FIG. 2).

The ribs 1244 are disposed at both ends of the second scanning lens 124a in the sub-main scanning direction (Z1-Z2 direction) and extend in the main scanning direction (Y1-Y2 direction). The ribs 1244 are formed as protruding parts when the second scanning lens 124a is molded from a resin material using a metal mold. By providing the ribs 1244, the second scanning lens 124a can be easily released from the metal mold even if it is enlarged, improving the manufacturing efficiency of the second scanning lens 124a and reducing manufacturing costs.

The second scanning lens 124a has an exit surface 1241 and an entrance surface 1242 for the light beams B1 and B2 formed in an area surrounded by the connecting portion 1243 and the rib 1244. The connecting portion 1243 and the rib 1244 do not interfere with the optical paths of the light beams B1 and B2.

The rib 1244 extending in the main scanning direction above the exit surface 1241 of the light beams B1 and B2 of the second scanning lens 124a (one side in the sub-scanning direction, Z1 direction) has an inclined surface 1244a on the side of the exit surface 1241 of the light beams B1 and B2 that inclines in a direction approaching the first scanning lens 123a as it moves upward (one side in the sub-scanning direction (Z1 direction)). In this embodiment, the inclined surface 1244a is also formed on the rib 1244 arranged below the exit surface 1241 (the other side in the sub-scanning direction (Z2 direction)), but this may be omitted.

Reflecting mirror 127a reflects light beam B1. Reflecting mirrors 125a and 126a reflect light beam B2. Reflecting mirrors 125b and 126b reflect light beam B3. Reflecting mirror 127b reflects light beam B4.

The light beam B1 focused by the first scanning lens 123a and the second scanning lens 124a is reflected by the reflecting mirror 127a and formed into an image on the scanned surface of the photosensitive drum 11a.

The light beam B2 focused by the first scanning lens 123a and the second scanning lens 124a is reflected by the reflecting mirrors 125a and 126a and is imaged on the scanned surface of the photosensitive drum 11b. At this time, the light beam B2 reflected by the reflecting mirror 125a can be moved closer to the second scanning lens 124a along the inclined surface 1244a and passed through it. This shortens the optical path of the light beam B2, making it possible to further miniaturize the scanning optical system 120.

The light beam B3 focused by the first scanning lens 123b and the second scanning lens 124b is reflected by the reflecting mirrors 125b and 126b and is imaged on the scanned surface of the photosensitive drum 11c. At this time, the light beam B3 reflected by the reflecting mirror 125b can be moved along the inclined surface 1244a toward the second scanning lens 124b and passed through it. This shortens the optical path of the light beam B3, making it possible to further miniaturize the scanning optical system 120.

The light beam B4 focused by the first scanning lens 123a and the second scanning lens 124a is reflected by the reflecting mirror 127b and is imaged on the scanned surface of the photosensitive drum 11d.

As described above, light beam B1 is irradiated to photoconductor drum 11a in response to input of Y (yellow) image data, forming an electrostatic latent image on photoconductor drum 11a, which is an image carrier. Light beam B2 is irradiated to photoconductor drum 11b in response to input of C (cyan) image data, forming an electrostatic latent image on photoconductor drum 11b, which is an image carrier. Light beam B3 is irradiated to photoconductor drum 11c in response to input of M (magenta) image data, forming an electrostatic latent image on photoconductor drum 11c, which is an image carrier. Light beam B4 is irradiated to photoconductor drum 11d in response to input of K (black) image data, forming an electrostatic latent image on photoconductor drum 11d, which is an image carrier.

According to this embodiment, the photosensitive drum (image carrier) 11b is disposed below the optical axis L of the second scanning lens 124a (the other side of the sub-scanning direction (Z2 direction)), and the pair of reflecting mirrors 125a, 125b is disposed above the optical axis L of the second scanning lens 124a (one side of the sub-scanning direction (Z1 direction)). The light beam B2 reflected by the pair of reflecting mirrors 125a, 125b passes between the first scanning lens 123a and the second scanning lens 124a and heads toward the photosensitive drum (image carrier) 11b. By using the pair of reflecting mirrors 125a, 125b to form an image of the light beam B1 focused by the second scanning lens 124a on the peripheral surface of the photosensitive drum (image carrier) 123a, the scanning optical system 120 for the light beam B1 can be made smaller while reducing the number of reflecting mirrors 125a, 125b. This allows the optical scanning device 12 to be made smaller.

The second scanning lens 124a also has a rib 1244 that extends in the main scanning direction (Y1-Y2 direction) above the exit surface 1241 of the light beam B1 (one side in the sub-scanning direction (Z1 direction)), and the rib 1244 has an inclined surface 1244a on the side of the exit surface 1241 of the light beam B1 that inclines in a direction approaching the first scanning lens 123a as it moves upward (one side in the sub-scanning direction (Z1 direction)). This allows the light beam B1 reflected by the reflecting mirror 125b to pass along the inclined surface 1244a and approach the second scanning lens 124a. This shortens the optical path of the light beam B1, making it possible to further miniaturize the scanning optical system 120.

In addition, the light source unit 121 has a collimator lens 221a and a cylindrical lens 221b integrated together. This shortens the optical paths of the light beams B1, B2, B3, and B2, making it possible to further miniaturize the scanning optical system 120.

The present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, in the above embodiment, a tandem color printer was used as an example of the image forming device 1, but the present invention is not limited to color printers and can be applied to electrophotographic color image forming devices such as color copiers and facsimiles.

In addition, in this embodiment, the optical scanning device 12 is disposed on the upper side Z1 of the photosensitive drums 11a to 11d, but the optical scanning device 12 may be disposed on the lower side Z2 of the photosensitive drums 11a to 11d. In this case, the light beams B1 to B4 emitted from the scanning optical system 120 are directed toward the lower side Z2. At this time, the second scanning lens 124a forms an inclined surface on the rib 1244 extending in the main scanning direction (Y1-Y2 direction) below the exit surface 1241 of the light beam B1 (the other side of the sub-scanning direction (Z2 direction)) that inclines toward the first scanning lens 123a as it moves downward (the other side of the sub-scanning direction (Z2 direction)). This shortens the optical path of the light beam B1 and makes the scanning optical system 120 more compact.

The present invention can be used in an optical scanning device that irradiates light onto an image carrier to form an electrostatic latent image. By using the present invention, it is possible to provide a compact optical scanning device and an image forming device equipped with the same.

1 Image forming device 2a to 2d Developing device 6 Tension roller 10 Image forming device 11a Photoconductor drum 11a to 11d Photoconductor drum 12 Optical scanning device 12a Housing 12b Storage section 12c Cover section 13a Charger 13a to 13d Charger 14a to 14d Cleaning device 17 Intermediate transfer belt 18 Fixing section 19 Discharge roller pair 25 Drive roller 26a to 26d Primary transfer roller 27 Driven roller 31 Belt cleaning device 32 Paper feed cassette 33, 39, 40 Paper transport path 33a Separation roller pair 33b Pickup roller 33c Registration roller pair 34 Secondary transfer roller 35 Stack tray 37 Paper discharge section 120 Scanning optical system 121 Light source section 121Y, 121C, 121M, 121K Light emitting module 122 Deflector 122a Polygon mirror 122b Scanner motor 123a, 123b First scanning lens 124a, 124b Second scanning lens 125a, 125b, 126a, 126b, 127a, 127b Reflection mirror 221a Collimator lens 221b Cylindrical lens 1241 Emission surface 1242 Incident surface 1243 Connection portion 1244 Rib 1244a Inclined surfaces B1, B2, B3, B2 Light beam C Rotation axis L Optical axis P Paper Z1 One side Z2 Other side

Claims (6)

a light source unit in which a plurality of light emitting modules for emitting light beams are arranged in a sub-scanning direction;
a deflector that rotates about an axis to reflect the light beam emitted from the light source unit and scans the peripheral surface of an image carrier in a main scanning direction;
a first scanning lens that focuses the light beam reflected by the deflector;
the second scanning lens which forms an image of the light beam having passed through the first scanning lens on a peripheral surface of the image carrier;
a pair of reflecting mirrors that reflect the light beam that has passed through the second scanning lens toward the image carrier on an imaging optical path;
an optical scanning device, characterized in that the light beam reflected by the pair of reflecting mirrors passes between the first scanning lens and the second scanning lens and travels toward the image carrier; The second scanning lens is
a rib extending in a main scanning direction on one side of the exit surface of the light beam in a sub-scanning direction,
2. The optical scanning device according to claim 1, wherein the rib has an inclined surface on the side of the light beam exit surface, the inclined surface being inclined in a direction approaching the first scanning lens as it moves toward one side in the sub-scanning direction. The light source unit includes:
a collimator lens that converts each of the light beams emitted from the light emitting module into a substantially parallel beam;
a cylindrical lens for converging each of the light beams that have passed through the collimator lens in a sub-scanning direction;
3. The optical scanning device according to claim 1, wherein the collimator lens and the cylindrical lens are integrated together. The light source unit includes:
a collimator lens that converts each of the light beams emitted from the light emitting module into a substantially parallel beam;
a cylindrical lens for converging each of the light beams that have passed through the collimator lens in a sub-scanning direction;
The collimator lens is integrally formed with sections corresponding to the respective light beams,
3. The optical scanning device according to claim 1, wherein the cylindrical lens is formed by integrally forming sections corresponding to the respective light beams. The collimator lens is integrally formed with sections corresponding to the respective light beams,
4. The optical scanning device according to claim 3, wherein the cylindrical lens is formed by integrally forming sections corresponding to the respective light beams. The optical scanning device according to claim 1 or 2,
The image carrier;
an image forming section that forms an image corresponding to the electrostatic latent image on a sheet.

Images