JP2020101698A - Optical scanning device, and image formation device including optical scanning device - Google Patents

Abstract

To solve the problem in which in a metal-made optical box, if a shield member and optical box are configured to be integrally molded, the shield member becomes also a metal-made, and in this case, burrs generate in a rim of an opening formed in the shield member and formed in the opening might shield a light beam passing through the opening, and thus, processing is required that removes the burr, but however, an interior of the optical box is processed into a complex shape for attaching optical system components, and it is not easy to apply the processing for removing the burr to the shield box integrally moded with the optical box.SOLUTION: A housing of an optical box and a shield member are configured to be a separated body.SELECTED DRAWING: Figure 7

Description

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

2. Description of the Related Art Some electrophotographic image forming apparatuses include an optical scanning device that irradiates a surface of a charged photosensitive drum with laser light to form an electrostatic latent image. The optical scanning device includes optical system components such as a light source, a lens, and a mirror, and an optical box that is a housing that covers these optical system components.

2. Description of the Related Art In recent years, colorization and speeding up have progressed in image forming apparatuses, and tandem type image forming apparatuses having a plurality of (four in many cases) photosensitive drums have become widespread.

A tandem type color image forming apparatus that forms an image with toner of four colors (yellow, magenta, cyan, and black) often includes an optical scanning device for four stations. As a configuration of the four-station optical scanning device, one having a rotary polygon mirror (for example, a polygon mirror) that rotates a light beam emitted from a light source is known. Since the rotary polygon mirror is a high-cost component, it may be provided in the central portion of the optical scanning device, and the light beam emitted from the light source may be distributed in the left and right directions of the rotary polygon mirror for scanning.

In the optical scanning device that distributes and scans the light beam in the left-right direction of the rotary polygon mirror in this manner, the light beam reflected by the incident surface of the lens of one (for example, the right side) station becomes “ghost light” and the other (for example, There is a problem that it enters the lens of the station on the left side and reaches the photosensitive drum, which causes an abnormal image. Therefore, a method of shielding ghost light has been proposed (for example, Patent Document 1).

Patent Document 1 discloses an optical scanning device in which a light shielding portion is integrally formed in the vicinity of the polygon mirror so as to shield the ghost light so as to face the reflecting surface of the polygon mirror. The light shielding member is formed with an opening for passing the light beam reflected by the rotating polygon mirror toward one of the stations. The light beam reflected by the rotating polygon mirror toward the other station and further reflected by the lens is blocked by the region outside the opening of the light blocking member.

JP 2005-004050 A

The higher the rotational speed of the rotary polygon mirror, the greater the vibration of the optical box due to the rotation of the rotary polygon mirror. Therefore, there is a method of increasing the rigidity of the optical box by suppressing the vibration of the optical box by making the material of the optical box metal.

Here, in the optical box made of metal, the light blocking member is also made of metal in the configuration in which the light blocking member and the optical box are integrally molded. In this case, burrs are generated at the edge of the opening formed in the light shielding member. The burr formed in the opening may block the light beam that passes through the opening, and therefore a process for removing the burr is necessary. However, the inside of the optical box is processed into a complicated shape in order to mount the optical parts, and it is not easy to remove the burr from the light blocking member integrally formed with the optical box.

In order to solve the above-described problems, an optical scanning device according to the present invention includes a metal housing, a first light source that emits a first light beam, and a second light source that emits a second light beam. The light source and the first light beam and the second light beam that are installed on the bottom of the housing and that rotate around a rotation axis and are incident obliquely with respect to the direction of the rotation axis sandwich the rotation axis. In the opposite direction, the rotating polygon mirror, the first lens for guiding the first light beam deflected by the rotating polygon mirror to the first photosensitive drum, and the first lens deflected by the rotating polygon mirror. A second lens for guiding the second light beam to a second photosensitive drum, and the first light beam deflected by the rotary polygon mirror is reflected by the first lens and directed toward the second lens, It is attached to the housing so as to be located on the optical path of the reflected light of the first light beam that has passed the side opposite to the side where the bottom is located with respect to the rotary polygon mirror in the direction of the rotation axis, A light blocking member that blocks the reflected light of the first light beam so that the reflected light of the first light beam does not go to the second photosensitive drum, and the light blocking member and the housing are different from each other. Characterized by being a body.

Further, the optical scanning device according to the present invention includes a first light source that emits a first light beam, a second light source that emits a second light beam, and a second light source that rotates about a rotation axis. A rotary polygon mirror that deflects the first light beam and the second light beam, which are incident obliquely with respect to a direction, to mutually opposite sides with the rotation axis interposed therebetween, and the first polygon deflected by the rotary polygon mirror. A first lens for guiding the first light beam to the first photosensitive drum, a second lens for guiding the second light beam deflected by the rotating polygonal mirror to the second photosensitive drum, and the rotating polygonal mirror An opening is formed through which the second light beam is deflected toward the second photosensitive drum, and the first light beam deflected by the rotating polygon mirror is reflected by the first lens. And a region outside the opening is located on the optical path of the reflected light of the first light beam that has passed through the outside of the rotary polygon mirror in the direction of the rotation axis toward the second lens. The reflected light of the first light beam is arranged so as to prevent the reflected light of the first light beam, which is arranged and has passed the outside of the rotary polygon mirror in the direction of the rotation axis, from going to the second photosensitive drum. A metal casing that houses a light blocking member, the rotary polygon mirror, the first lens, the second lens, and the light blocking member, and is provided with a mounting portion to which the light blocking member is attached. A body, and the light shielding member and the housing are separate bodies.

According to the image forming apparatus of the present invention, since the optical box and the light blocking member are separate bodies, it is easy to provide the light blocking member in the optical box even if the optical box is made of metal.

FIG. 3 is a schematic cross-sectional view of the image forming apparatus. The whole perspective view of an optical scanning device. The figure for demonstrating arrangement|positioning of a light source. The figure for demonstrating the optical path of the light beam radiate|emitted from the light source. FIG. 6 is a diagram for explaining an optical path of a light beam deflected by a rotating polygon mirror. FIG. 6 is a diagram for explaining the function of the light shielding member. FIG. 6 is a diagram for explaining a method of attaching the light shielding member to the housing. FIG. 4 is a diagram for explaining a positional relationship between a light blocking member and a lens. The figure for demonstrating the inclination of the light shielding member with respect to an attachment part. FIG. 6 is a diagram for explaining an optical path of a light beam reflected upward by the light blocking member. FIG. 4 is a diagram for explaining an optical path of a light beam reflected downward by a light blocking member.

Embodiments for carrying out the present invention will be described below with reference to the drawings. It should be noted that the dimensions, materials, shapes, relative arrangements, and the like of the components described below are not intended to limit the scope of the present invention thereto unless otherwise specified.

(Image forming device)
FIG. 1 is a schematic cross-sectional view showing the overall configuration of image forming apparatus 1 according to the present embodiment. As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment has four photosensitive drums 50Y corresponding to yellow (Y), magenta (M), cyan (C), and black (Bk). 50M, 50C, 50Bk (hereinafter, also collectively referred to as a photosensitive drum 50) are provided. The photosensitive drum 50Y is an example of the first photosensitive drum, and the photosensitive drum 50Bk is an example of the second photosensitive drum. The image forming apparatus 1 is a tandem-type color laser beam printer that includes four image forming units 10Y, 10M, 10C, and 10Bk that form a toner image for each color.

The image forming apparatus 1 includes an intermediate transfer belt 20 to which the toner images formed by the image forming units 10Y, 10M, 10C, and 10Bk (hereinafter, also simply referred to as the image forming unit 10) are transferred. The intermediate transfer belt 20 transfers the toner image transferred from each image forming unit 10 onto the recording paper P. The image forming units 10Y, 10M, 10C, and 10Bk have substantially the same configuration except that the colors of the toners used in the image forming units 10 are different. Hereinafter, the image forming unit 10Y will be described as an example of the image forming unit 10. A duplicate description of the image forming units 10M, 10C, and 10Bk will be omitted.

The image forming unit 10Y develops the photosensitive drum 50Y, a charging roller 12Y that uniformly charges the photosensitive drum 50Y, and an electrostatic latent image formed on the photosensitive drum 50Y by the optical scanning device 40, which will be described later, with toner. The developing device 13Y for forming a toner image and the primary transfer roller 15Y for transferring the formed toner image to the intermediate transfer belt 20 are provided. The primary transfer roller 15Y forms a primary transfer portion with the photosensitive drum 50Y via the intermediate transfer belt 20. The toner image formed on the photosensitive drum 50Y is transferred to the intermediate transfer belt 20 by applying a predetermined transfer voltage to the primary transfer roller 15Y.

The intermediate transfer belt 20 is an endless belt wound around a first belt carrying roller 21 and a second belt carrying roller 22, and rotates in the arrow H direction. The toner images formed by the image forming units 10Y, 10M, 10C, and 10Bk are transferred onto the rotating intermediate transfer belt 20. Here, the four image forming units 10 are arranged in parallel below the intermediate transfer belt 20 in the vertical direction. As a result, the toner image formed on the photosensitive drum 50 is transferred to the intermediate transfer belt 20 according to the image information of each color.

Further, the first belt conveying roller 21 and the secondary transfer roller 68 are pressed against each other with the intermediate transfer belt 20 interposed therebetween. As a result, the first belt conveyance roller 21 forms a secondary transfer portion between itself and the secondary transfer roller 68 via the intermediate transfer belt 20. The recording paper P is inserted into the secondary transfer portion, and the toner image is transferred from the intermediate transfer belt 20. The transfer residual toner remaining on the surface of the intermediate transfer belt 20 is collected by a cleaning device (not shown).

Here, each image forming unit 10 forms a yellow toner image from the upstream side with respect to the secondary transfer unit in the rotation direction of the intermediate transfer belt 20 (direction of arrow H), and a magenta toner image. The image forming unit 10M that forms the toner image, the image forming unit 10C that forms the cyan toner image, and the image forming unit 10Bk that forms the black toner image are sequentially arranged.

Further, below the image forming units 10 in the vertical direction, laser light (light beam) is scanned on each of the photosensitive drums 50 corresponding to each color to form an electrostatic latent image on the surface of each photosensitive drum 50. A scanning device 40 is provided.

The optical scanning device 40 includes an optical box 105 and a rotating polygon mirror 41. The optical box 105 also includes a metal housing 107 and a cover 106 that is an upper lid of the housing 107. The housing 107 houses optical members such as the rotating polygon mirror 41 and a reflecting mirror. Further, the optical box 105 in the present embodiment has four semiconductor lasers (not shown) that emit laser light modulated according to image information of each color. The plurality of semiconductor lasers are light sources for exposing the corresponding photosensitive drums 50, respectively. The rotary polygon mirror 41 is rotated at high speed by a polygon motor (not shown). As a result, each laser beam emitted from each semiconductor laser is reflected so as to scan the photosensitive drum 50 along the rotation axis direction (main scanning direction) of each photosensitive drum 50. Each laser beam emitted from the semiconductor laser and reflected by the rotary polygon mirror 41 is guided by an optical system component such as a lens arranged inside the optical box 105, and a transmission member that covers each emission port provided in the cover 106. The light is emitted from the inside of the optical box 105 to the outside via 42Y, 42M, 42C, and 42Bk (hereinafter, also simply referred to as the transmission member 42). The laser light emitted from the optical box 105 exposes each photosensitive drum 50.

Here, the housing 107 in the present embodiment is made of metal (for example, aluminum). By making the casing 107 made of metal, the rigidity can be increased as compared with the casing made of resin. In recent years, as the image forming apparatus operates at high speed, the rotational speed of the rotary polygon mirror has also increased. The higher the rotational speed of the rotary polygon mirror, the greater its vibration. Since the vibration of the rotary polygon mirror propagates to the optical box itself, the vibration of the optical box also increases as the vibration of the rotary polygon mirror increases. When the vibration of the optical box increases, an optical member such as a lens provided inside the housing may come off and its position may shift. Since the metal housing has higher rigidity than the resin housing, the vibration of the optical box itself caused by the rotation of the rotary polygon mirror is smaller than that of the optical box using the resin housing.

Further, the higher the rotational speed of the rotary polygon mirror, the louder the wind noise of the rotary polygon mirror. Since the metal casing has higher soundproofness than the resin casing, noise emitted from the inside of the optical scanning device to the outside is small.

Further, the metal case has a smaller amount of deformation due to heat than the resin case. In general, the faster the rotary polygon mirror rotates, the more heat is generated from the motor that rotates the rotary polygon mirror. Therefore, the temperature of the inside of the optical box tends to increase as the optical scanning device has a higher rotational speed of the rotary polygon mirror. By making the material of the housing metallic, it is possible to suppress the deformation of the housing even when the temperature inside the optical box rises. In the above description, the casing 107 is made of metal, but the material of the cover 106 is not particularly mentioned. However, if the cover 106 is also made of metal, vibrations and noises will not occur. It can be further suppressed. The deformation of the optical box 105 itself due to heat can be further suppressed by using a metal cover.

The image forming apparatus 1 of the present embodiment shown in FIG. 1 has a configuration in which a light beam is emitted from one optical scanning device 40 to each of the four photosensitive drums 50, but the embodiment is not limited to this. is not. For example, one optical scanning device 40 is provided for each of the two image forming units 10, that is, two optical scanning devices 40 are provided for the image forming apparatus 1 as a whole, and the respective optical scanning devices 40 are respectively connected to the corresponding two photosensitive drums. A light beam may be emitted.

On the other hand, the recording paper P is housed in the paper feed cassette 2 arranged below the image forming apparatus 1. Then, the recording paper P is fed by the pickup roller 24 to the separation nip portion formed by the feeding roller 25 and the retard roller 26. Here, the drive of the retard roller 26 is transmitted so as to rotate in the reverse direction when a plurality of recording sheets P are fed by the pickup roller 24. Thus, the recording paper P is prevented from being double-fed by conveying the recording papers P one by one. The recording papers P, which are conveyed one by one by the feeding roller 25 and the retard roller 26, are conveyed along a right side surface of the image forming apparatus 1 to a conveyance path 27 extending substantially vertically.

Then, the recording sheet P is conveyed from the lower side to the upper side in the vertical direction of the image forming apparatus 1 through the conveying path 27 and is conveyed to the registration roller 29. The registration roller 29 temporarily stops the conveyed recording paper P and corrects the skew of the recording paper P. After that, the registration roller 29 conveys the recording paper P to the secondary transfer portion at the timing when the toner image formed on the intermediate transfer belt 20 is conveyed to the secondary transfer portion. After that, the recording paper P on which the toner image has been transferred in the secondary transfer portion is conveyed to the fixing device 3, and is heated and pressed by the fixing device 3, so that the toner image is fixed on the recording paper P. Then, the recording paper P on which the toner image is fixed is discharged by the discharge roller 28 to a discharge tray 420 provided outside the image forming apparatus 1 and above the main body of the image forming apparatus 1.

(Optical scanning device)
As described above, in the full-color image formation by the image forming apparatus 1 of the present embodiment, the optical scanning device 40 uses the photosensitive drums 50Y, 50M, 50C, and 50Bk of the image forming unit 10 according to the image information of the respective colors. Are exposed at each predetermined timing. As a result, a toner image of each color corresponding to the image information of each color is formed on each photosensitive drum 50. In order to obtain a high-quality full-color image, the formation position of each electrostatic latent image formed by the optical scanning device 40 needs to be reproduced with high accuracy.

FIG. 2 is a schematic perspective view of the optical scanning device 40 according to the present embodiment. As shown in FIG. 2, the optical box 105 included in the optical scanning device 40 includes a metal casing 107 and a cover 106 corresponding to an upper lid of the casing 107.

As shown in FIG. 2, the cover 106 has emission ports through which the light beams for exposing the respective photosensitive drums 50 pass, and the transmission members 42Y, 42M, 42C, 42Bk (hereinafter, (Also referred to as a transparent member 42) is provided.

The cover 106 and the housing 107 are engaged with each other by a snap fit mechanism. As shown in FIG. 2, the cover 106 is formed with engaging portions 106a to 106e. The cover 106 is attached to the housing 107 by engaging the respective engaging portions 106 a to 106 e with the housing 107. In this way, the cover 106 is fixed to the housing 107 to form one optical box 105. The method of fixing the cover 106 to the housing 107 is not limited to the above-described snap fit, and may be fixed with a screw, a screw, or the like.

Hereinafter, the internal structure of the optical box 105 will be described in more detail with reference to FIGS. 3 to 5. FIG. 3 is a diagram for explaining the arrangement of each of the light source units 61a, 61b, 71a, 71b. FIG. 3 is a diagram of the rotary polygon mirror 41 viewed from the light source units 61a, 61b, 71a, 71b. In FIG. 3, a light beam travels from each of the light source units 61a, 61b, 71a, 71b toward the rotary polygon mirror 41, that is, in the direction from the front side to the back side of the paper surface. The rotary polygon mirror 41 is installed on the bottom portion 101 of the housing 107 and rotates about a rotation axis.

FIG. 4 is a diagram for explaining an optical path of a light beam 60a (an example of a first light beam) emitted from the light source unit 61a and an optical path of a light beam 70a emitted from the light source unit 71a. As shown in FIG. 4, the light source unit 61a includes a semiconductor laser 62 (an example of a first light source), a collimator lens 63, and a sub-scanning diaphragm 64. The light beam 60a emitted from the semiconductor laser 62 is converted into parallel light by the collimator lens 63 and travels. The light beam 60a emitted from the light source unit 61a has a desired light beam width defined by the main scanning diaphragm 66, and is condensed on the rotary polygon mirror 41 by the cylindrical lens 65. Further, in FIG. 4, the light source unit 61a is arranged such that the central axis 60b of the light beam 60a is inclined by an angle α with respect to a plane orthogonal to the rotation axis of the rotary polygon mirror 41. The light beam 60a emitted from the light source unit 61a is obliquely incident on the rotary polygon mirror 41.

Further, like the light source unit 61a, the light source unit 71a also has a semiconductor laser 72. The light source unit 71a is also arranged such that the central axis 70b of the light beam 70a is inclined by an angle α with respect to a plane orthogonal to the rotation axis of the rotary polygon mirror 41. The light beam 70a emitted from the light source unit 71a obliquely enters the rotary polygon mirror 41.

Although not shown in FIG. 4, the light source unit 61b is arranged on the inner side of the light source unit 61a, and the light source unit 71b is arranged on the inner side of the light source unit 71a. The light source unit 61b also includes a semiconductor laser (an example of a second light source) not shown. The light source unit 71b also includes a semiconductor laser (not shown).

The light beam emitted from the semiconductor laser of the light source unit 61b (an example of the second light beam) is also inclined by an angle α with respect to the surface orthogonal to the rotation axis of the rotary polygon mirror 41, similarly to the light beam 60a. .. Further, the light beam emitted from the semiconductor laser of the light source unit 71b is also inclined by an angle α with respect to the surface orthogonal to the rotation axis of the rotary polygon mirror 41, similarly to the light beam 70a. That is, both the light beam emitted from the light source unit 61b and the light beam emitted from the light source unit 71b are obliquely incident on the rotary polygon mirror 41.

Next, the optical path of each light beam emitted from each light source unit 61a, 61b, 71a, 71b and reflected by the rotary polygon mirror 41 will be described with reference to FIG. The rotating polygon mirror 41 is installed in the central portion of the housing 107, and has a light beam 60a (an example of a first light beam) emitted from the light source unit 61a and a light beam (second light beam) emitted from the light source unit 61b. And an example of the light beam of 1) and the light beam of 2) are deflected to the opposite sides of the rotation axis. Similarly, the rotary polygon mirror 41 deflects the light beam 70a emitted from the light source unit 71a and the light beam emitted from the light source unit 71b to opposite sides with the rotation axis interposed therebetween. The photosensitive drum 50Y exposed by the light beam 60a emitted from the light source unit 61a which is an example of the first light beam is emitted from the first photosensitive drum and the light source unit 61b which is an example of the second light beam. Although the photosensitive drum 50Bk exposed by the light beam is the second photosensitive drum, the correspondence relationship between the light beam and the photosensitive drum is not limited to the relationship given here. For example, when the first light beam exposes the photosensitive drum 50M, the photosensitive drum 50M is referred to as a first photosensitive drum, and when the second light beam exposes the photosensitive drum 50C, the photosensitive drum 50C is referred to as a second photosensitive drum. It may be referred to as a photosensitive drum.

Here, as shown in FIG. 5, the rotary polygon mirror 41 is installed on the bottom portion 101 of the housing 107. In general, the rotary polygon mirror 41 may be provided on a substrate, and in this case, the substrate is also considered to be the bottom portion 101 of the housing 107. As described above, the rotary polygon mirror 41 may be installed on the bottom portion 101 of the housing 107 via another member such as a substrate.

The light beam 60a emitted from the light source unit 61a is deflected by the rotary polygon mirror 41, and passes as the light beam 94 through the opening 202a formed in the light shielding member 201a. The light beam 94 emitted from the light source unit 61a and deflected by the rotary polygon mirror 41 passes through a lens 400a (an example of a first lens). The lens 400a has a function of guiding the light beam 94 to the photosensitive drum 50Y. The light beam 94 that has passed through the lens 400a then passes through the lens 43Y and is reflected by the reflection mirror 44. The light beam 94 reflected by the reflection mirror 44 passes through the transmission member 42Y provided on the cover 106 to expose the photosensitive drum 50Y. A light blocking member 201a is provided between the rotary polygon mirror 41 and the lens 400a closest to the rotary polygon mirror 41.

The light beam 70a emitted from the light source unit 71a is deflected by the rotating polygon mirror 41, and passes as the light beam 95 through the opening 202a formed in the light shielding member 201a. The light beam 95 emitted from the light source unit 71a and deflected by the rotary polygon mirror 41 passes through the lens 400a, is then reflected by the reflection mirror 45a and the reflection mirror 45b, and passes through the lens 43M. The light beam 95 that has passed through the lens 43M is reflected by the reflection mirror 45c, passes through the transmissive member 42M provided on the cover 106, and exposes the photosensitive drum 50M.

The light beam 96 emitted from the light source unit 61b and deflected by the rotary polygon mirror 41 passes through the opening 202b formed in the light blocking member 201b. The light beam 96 emitted from the light source unit 61b and deflected by the rotary polygon mirror 41 passes through the lens 400b (an example of a second lens). The lens 400b has a function of guiding the light beam 96 to the photosensitive drum Bk. The light beam 96 that has passed through the lens 400b then passes through the lens 43Bk and is reflected by the reflection mirror 46. The light beam 96 reflected by the reflecting mirror 46 passes through the transmitting member 42Bk provided on the cover 106 to expose the photosensitive drum 50Bk. A light blocking member 201b is provided between the rotary polygon mirror 41 and the lens 400b closest to the rotary polygon mirror 41.

The light beam 97 emitted from the light source unit 71b and deflected by the rotary polygon mirror 41 passes through the opening 202b formed in the light blocking member 201b. The light beam 97 emitted from the light source unit 71b and deflected by the rotary polygon mirror 41 passes through the lens 400b, is then reflected by the reflection mirror 46a and the reflection mirror 46b, and passes through the lens 43C. The light beam 97 that has passed through the lens 43C is reflected by the reflection mirror 46c, passes through the transmissive member 42C provided on the cover 106, and exposes the photosensitive drum 50C.

(About light-shielding member)
Next, the functions of the light blocking member 201a and the light blocking member 201b will be described with reference to FIG. As shown in FIG. 6, the light blocking member 201a is attached to the housing 107 between the rotary polygon mirror 41 and the lens 400a.

Here, for simplification of description, the light beam 94 deflected by the rotary polygon mirror 41 is virtually assumed to be from the light beam 94a deflected by the rotary polygon mirror 41 until it enters the lens 400a, and the lens The light beam 94b passing through 400a and the light beam 94c reflected by the lens 400a will be considered separately.

As shown in FIG. 6, most of the light beam 94a deflected by the rotary polygon mirror 41 passes through the lens 400a and becomes the light beam 94b. On the other hand, part of the light beam 94a is reflected by the surface of the lens 400a, and a light beam 94c (reflected light of the light beam 94a) is generated. The unintended light reflected by the lens surface, such as the light beam 94c, may be referred to as flare light.

The light beam 94c reflected on the surface of the lens 400a passes outside the rotary polygon mirror 41 in the direction of the rotation axis of the rotary polygon mirror 41. Specifically, in the case of the light beam 94c shown in FIG. 6, it passes above the rotary polygon mirror 41 in the vertical direction. In other words, the light beam 94c passes through the rotary polygon mirror 41 on the side opposite to the side on which the bottom portion 101 is located. In this way, a part of the light component (light beam 94) of the light beam 94 that is deflected by the rotary polygon mirror 41 and travels toward the station on one side (the station corresponding to yellow and magenta in this embodiment) 94c) may progress to the station on the other side.

The light beam 94c travels toward the other station (stations corresponding to cyan and black in the present embodiment) to expose the photosensitive drum 50C corresponding to cyan and the photosensitive drum 50Bk corresponding to black. A light blocking member 201b is provided to prevent this. As shown in FIG. 6, since the light blocking member 201b is attached to the housing 107, the light beam 94c reflected by the lens 400a and passing through the upper side of the rotary polygon mirror 41a is transmitted to the rotary polygon mirror 41 and the lens 400b. Between them, it hits the light blocking member 201b. This can prevent the light beam 94c from exposing the photosensitive drum 50C corresponding to cyan and the photosensitive drum 50Bk corresponding to black. In other words, the light blocking member 201b is located on the optical path of the light beam 94c generated by being reflected by the lens 400a. Specifically, in the light blocking member 201b, a region outside the opening 202b in the direction of the rotation axis of the rotary polygon mirror 41 is located on the optical path of the light beam 94c. Similarly, the flare light generated by being reflected by the lens 400b in the light beam 96 deflected by the rotary polygon mirror 41 is blocked by the light blocking member 201a. In other words, the light blocking member 201b is located on the optical path of the reflected light of the light beam 96 that is reflected by the lens 400b. Specifically, in the light path of the light beam reflected by the lens 400a of the light beam 96, the region of the light blocking member 201a outside the opening 202a is located in the direction of the rotation axis of the rotary polygon mirror 41. The light shielding member 201a and the light shielding member 201b are members separate from the housing 107, and the material thereof may be the same metal as the housing 107 or may be a resin member. Absent. The reason why the light shielding members 201a and 201b and the housing 107 are separate members will be described later.

(How to attach the light blocking member to the case)
FIG. 7 is a diagram for explaining a method of attaching the light blocking member 201a to the housing 107. FIG. 7A shows an exploded perspective view of the mounting portion 230a, the mounting portion 230b, and the light shielding member 201a. Further, FIG. 7B is a diagram showing a state in which the light blocking member 201a is attached to the attachment portions 230a and 230b. Since the method of attaching the light blocking member 201b to the housing 107 is substantially the same as the method of attaching the light blocking member 201a to the housing 107, a method of attaching the light blocking member 201a to the housing 107 will be described below. Only explained.

As shown in FIG. 7A, the housing 107 is provided with a mounting portion 230a and a mounting portion 230b to which the light shielding member 201a is mounted. One end side of the light shielding member 201a in the longitudinal direction of the light shielding member 201a, that is, the main scanning direction is attached to the attachment portion 230a. On the other hand, the other end side of the light shielding member 201a in the longitudinal direction of the light shielding member 201a is attached to the attachment portion 230b. In addition, in the present embodiment, the mounting portions 230a and 230b and the housing 107 are integrally molded, but they may be separate bodies.

The mounting portion 230a includes a mounting portion 213a on which the light shielding member 201a is mounted, support portions 212a and 214a for supporting the light shielding member 201a mounted on the mounting portion 213a so as to sandwich the light shielding member 201a in the sub-scanning direction. Equipped with.

The mounting portion 230b includes a mounting portion 213b on which the light shielding member 201a is mounted, and a support portion 212b and a supporting portion 214b that support the light shielding member 201a mounted on the mounting portion 213b so as to sandwich it in the sub-scanning direction. And

As shown in FIG. 7A, one end of the light shielding member 201a is sandwiched between the support portions 212a and 214a, and the other end thereof is sandwiched between the support portions 212b and 214b. As a result, the position of the light blocking member 201a with respect to the mounting portion 230a and the mounting portion 230b in the sub-scanning direction is determined.

Further, one end of the light shielding member 201a in the longitudinal direction of the light shielding member 201a contacts the wall surface 209a, and the other end of the light shielding member 201a in the longitudinal direction of the light shielding member 201a contacts the wall surface 209b. As a result, the position of the light blocking member 201a with respect to the mounting portions 230a and 230b in the main scanning direction is determined. As described above, the light blocking member 201a is positioned with respect to the mounting portions 230a and 230b.

Here, each of the support portion 212a and the support portion 214a is inclined with respect to the direction of the rotation axis of the rotary polygon mirror 41. Further, each of the support portion 212b and the support portion 214b is also inclined with respect to the direction of the rotation axis of the rotary polygon mirror 41. Therefore, the light blocking member 201a attached to the attachment portions 230a and 230b is inclined with respect to the rotation axis of the rotary polygon mirror 41. The effect of inclining the light blocking member 201a with respect to the rotation axis of the rotary polygon mirror 41 will be described later. In the present embodiment, in order to incline the light blocking member 201a with respect to the rotation axis of the rotary polygon mirror 41, the portions of the mounting portions 230a and 230b to which the light blocking member 201a is attached are rotated. Although it is inclined with respect to the axis, the embodiment is not limited to this form. For example, in the light shielding member 201a, a portion that contacts the support portion 212a and a portion that contacts the support portion 212b, a portion that contacts the mounting portion 213a (an example of a contact surface) and a portion that contacts the mounting portion 213b (contact The light blocking member 201a may be formed so as to be inclined with respect to an example of the surface. In this case, it is not necessary to incline the portion of the attachment portion 230a and the attachment portion 230b to which the light blocking member 201a is attached with respect to the rotation axis of the rotary polygon mirror 41.

Further, a recess 214b is formed in the mounting portion 230b. As shown in FIG. 7B, an adhesive portion 208b, which is the other end side of the light shielding member 201a in the longitudinal direction of the light shielding member 201b, is fitted into the recess 214b. When the light blocking member 201a is positioned with respect to the mounting portion 230a and the mounting portion 230b, the adhesive portion 208b is in a state of being fitted into the recess 214b. In this state, the adhesive is applied to the adhesive portion 208b. As a result, the bonding portion 208b of the light blocking member 201a and the recess 214b of the mounting portion 230b are bonded, and the fixing of the light blocking member 201a to the mounting portion 230b is completed. Although not shown, a recess 214a is also formed in the mounting portion 230a so as to correspond to the recess 214b. An adhesive portion 208a formed on the other end side of the light shielding member 201a in the longitudinal direction of the light shielding member 201a fits into the recess 214a. The adhesive is applied to the adhesive portion 208a in a state where the adhesive portion 208a of the light shielding member 201a is fitted in the recess 214a. As a result, the bonding portion 208a of the light blocking member 201a and the recess 214a of the mounting portion 230a are bonded, and the fixing of the light blocking member 201a to the mounting portion 230a is completed. From the above, the fixing of the light shielding member 201a to the mounting portions 230a and 230b is completed. As a matter of course, with the adhesive applied to the recesses 214a and 214b in advance, the light blocking member 201a is installed on the mounting portions 230a and 230b, and the light blocking member 201a is fixed to the mounting portions 230a and 230b. It doesn't matter.

FIG. 8 is a diagram for explaining the positional relationship between the light blocking member 201a attached to the attachment portion 230a and the attachment portion 230b and the lens 400a. As shown in FIG. 8, the lens 400a is attached to the attachment portion 230a and the attachment portion 230b. In this embodiment, the lens 400a is adhesively fixed to the mounting portions 230a and 230b with an adhesive.

In the present embodiment, the light blocking member 201a is arranged between the rotary polygon mirror 41 and the lens 400a, but the light blocking member 201a is different from the lens 400a on which the rotary polygon mirror 41 is arranged. It may be arranged on the opposite side. In this case, the light blocking member 201a blocks the light beam that is deflected by the rotary polygon mirror 41, reflected by the lens 400b, and passed through the lens 400a. Similarly, the light blocking member 201b may be arranged on the opposite side of the lens 400b from the side on which the rotary polygon mirror 41 is arranged. In this case, the light blocking member 201b blocks the light beam that is deflected by the rotary polygon mirror 41, reflected by the lens 400a, and passed through the lens 400b. Alternatively, the light beam that has passed above the lens 400a or above the lens 400b may be blocked.

Moreover, although the opening 202a is formed in the light shielding member 201a in the present embodiment, a mode in which the opening 202a is not necessary is also conceivable. For example, in the case where the above-described mounting portion 230a and mounting portion 230b are provided so as to project from the bottom portion 101 of the housing 107, when the light shielding member 201a is mounted on these mounting portion 230a and mounting portion 230b, the housing 107 is attached. An opening surrounded by the bottom portion 101, the mounting portion 230a, the mounting portion 230b, and the light shielding member 201a is formed. This opening can function as a portion corresponding to the opening 202a of the light shielding member 201a described above. For example, the mounting portion 230a and the mounting portion 230b are protrusions projecting 100 mm from the bottom portion 101 of the housing 107, and the distance between the portion of the light shielding member 201a mounted on the mounting portion 230a and the portion mounted on the mounting portion 230b is 800 mm. In this case, an opening having a height of 100 mm and a width of 800 mm is formed. Of course, the opening 202a need not be formed in the light shielding member 201a in this case, and may be, for example, a rectangular plate member. By configuring the light blocking member 201b in the same manner as this, it is not necessary to form the opening 202b in the light blocking member 201b.

FIG. 9 is a diagram for explaining the inclination of the light blocking member 201a. FIG. 9A is a view of the light blocking member 201a fixed to the mounting portions 230a and 230b as viewed from the side opposite to the side where the lens 400a is arranged. As shown in FIG. 9A, the lower side of the light shielding member 201a is bent. The surfaces 221a and 221b formed by being bent in this manner are supported by the mounting portions 230a and 230b, respectively.

9B is a cross-sectional view of the light shielding member 201a taken along the cross section indicated by the broken line A in FIG. 9A. As shown in FIG. 9B, the light blocking member 201a is inclined by 87° with respect to the mounting portion 213a of the mounting portion 230a and the mounting portion 213b of the mounting portion 230b. In other words, the light shielding member 201a is bent so that the surface 221a (221b) is inclined by 87° with respect to the surface of the light shielding member 201a where the opening 202a is formed.

Next, the advantages of providing the light blocking member 201a and the light blocking member 201b as separate bodies from the housing 107 will be described. Here, consider a case where the light blocking member 201a and the light blocking member 201b are integrally molded with the metal casing 107. In this case, of course, the light blocking member 201a and the light blocking member 201b are also made of metal. As described above, the light shielding member 201a has the opening 202a formed therein, and the light shielding member 201b has the opening 202b formed therein. Although it is necessary to perform processing such as cutting in order to form these openings, it is not easy to perform such processing inside the housing 107. Particularly in the case of the metal casing 107, burrs are generated on the edge of the opening even if the processing for forming the opening is performed. Secondary processing for removing this burr is also required, and it is difficult to form an opening with a small amount of burr in these operations inside the housing 107 without damaging the surroundings. Further, the processing also requires a cost. When the light blocking member 201a and the light blocking member 201b are separate from the housing 107, the light blocking member 201a and the light blocking member 201b which are separate members are formed with the openings 202a and 202b in advance, and then the light blocking member 201a and the light blocking member 201b are formed. 201b can be attached to the housing 107.

(About the light beam reflected by the light blocking member)
Hereinafter, the effect of inclining the light blocking member 201a with respect to the direction of the rotation axis of the rotary polygon mirror 41 will be described with reference to FIGS. 10 and 11. This effect is particularly remarkable when the light shielding member 201a is made of metal.

FIG. 10A is a diagram for explaining how the light beam 94c deflected by the rotary polygon mirror 41 and reflected by the lens 400a is reflected by the reflecting surface of the light shielding member 201a. As shown in FIG. 10A, in the present embodiment, the light beam 94b is 2.2° and the reflecting surface of the light shielding member 201a is 5° with respect to the surface of the rotating polygon mirror 41 whose normal is the rotation axis. ° Tilt is arranged. The distance between the light shielding member 201a and the final reflection mirror 44 is about 160 mm. Therefore, the light beam 94d advances upward at an angle of 12.2° with respect to the horizontal plane shown by the broken line in FIG. 10A, and at the position of the mirror 44, the light blocking member 201a is directed in the direction of the rotation axis of the rotary polygon mirror 41. A ray of about 34 mm diverges from the point reflected at. Since the width of the mirror 44 in the sub-scanning direction is 10 mm, the light beam 94d is not reflected by the mirror 44 and does not reach the photosensitive drum 50Y.

Here, the light beam 94d travels toward the wall portion of the housing 107 without reaching the photosensitive drum 50Y, but since the housing 107 is made of metal and is formed by the die casting method, the wall surface thereof is It is a casting surface and has fine irregularities. Therefore, even if the light beam 94d is irradiated, the diffusion effect is high. As a result, the light beam 94d reaching the wall surface of the casing 107 is diffused and does not affect the image. As described above, the light blocking member 201a is inclined with respect to the direction of the rotation axis of the rotary polygon mirror 41 so that the light beam 94c deflected by the rotary polygon mirror 41 and reflected by the lens 400a does not go to the photosensitive drum 50Y. There is. In the present embodiment, it is inclined by 5°.

FIG. 10B is a diagram for explaining how the light beam 95c deflected by the rotary polygon mirror 41 and reflected by the lens 400a is reflected by the light blocking member 201a. As shown in FIG. 10B, in the present embodiment, the light beam 95b is tilted at 2.2° and the light blocking member 201a is tilted at 5° with respect to the surface having the rotation axis of the rotary polygon mirror 41 as the normal line. It is arranged. The distance between the light blocking member 201a and the reflection mirror 45a is about 100 mm as shown in FIG. Therefore, the light beam 95d travels upward at an angle of 7.8° with respect to the horizontal plane shown by the broken line in FIG. 10B, and at the position of the mirror 44, the light shielding member 201a is directed in the direction of the rotation axis of the rotary polygon mirror 41. A ray of about 34 mm diverges from the point reflected at. Since the width of the mirror 44 in the sub-scanning direction is 10 mm, the light beam 95d is not reflected by the mirror 44 and does not reach the photosensitive drum 50M.

Here, the light beam 95d travels toward the wall portion of the housing 107 without reaching the photosensitive drum 50M, but since the housing 107 is made of metal and is formed by the die casting method, the wall surface thereof is It is a casting surface and has fine irregularities. Therefore, the diffusion effect is high even when the light beam 95d is irradiated. As a result, the light beam 95d reaching the wall surface of the casing 107 is diffused and does not affect the image. As described above, the light blocking member 201a is inclined with respect to the direction of the rotation axis of the rotary polygon mirror 41 so that the light beam 95c deflected by the rotary polygon mirror 41 and reflected by the lens 400a does not go toward the photosensitive drum 50M. There is. In the present embodiment, it is inclined by 7.8°.

11A and 11B, the light shielding member 201a is arranged so that the upper side of the light shielding member 201a is more downstream than the lower side of the light shielding member 201a in the traveling direction of the light beam 94a. It is a figure when it inclines with respect to a rotating shaft.

As shown in FIG. 11A, in the present embodiment, the light beam 94a is 2.2° and the light blocking member 201a is 7.8° with respect to the surface whose normal is the rotation axis of the rotary polygon mirror 41. It is placed at an angle. The distance between the light shielding member 201a and the final reflection mirror 44 is about 160 mm. Therefore, the light beam 94d travels downward at an angle of 7.8° with respect to the horizontal plane shown by the broken line in FIG. As a result, the light beam 94d is not reflected by the mirror 45a and does not reach the photosensitive drum 50Y.

Here, the light beam 94d travels toward the wall portion of the housing 107 without reaching the photosensitive drum 50Y, but since the housing 107 is made of metal and is formed by the die casting method, the wall surface thereof is It is a casting surface and has fine irregularities. Therefore, even if the light beam 94d is irradiated, the diffusion effect is high. As a result, the light beam 94d reaching the wall surface of the casing 107 is diffused and does not affect the image. As described above, the light blocking member 201a is inclined with respect to the direction of the rotation axis of the rotary polygon mirror 41 so that the light beam 94c deflected by the rotary polygon mirror 41 and reflected by the lens 400a does not go to the photosensitive drum 50Y. There is. In the present embodiment, it is inclined by 7.8°.

As shown in FIG. 11B, in the present embodiment, the light beam 95a is 2.2° and the light blocking member 201a is 12.2° with respect to the surface having the rotation axis of the rotary polygonal mirror 41 as the normal line. It is placed at an angle. The distance between the light blocking member 201a and the reflection mirror 45a is about 100 mm. Therefore, the light beam 95d advances downward at an angle of 12.2° with respect to the horizontal plane shown by the broken line in FIG. As a result, the light beam 95d is not reflected by the mirror 45a and does not reach the photosensitive drum 50M.

Here, the light beam 95d travels toward the wall portion of the housing 107 without reaching the photosensitive drum 50M, but since the housing 107 is made of metal and is formed by the die casting method, the wall surface thereof is It is a casting surface and has fine irregularities. Therefore, the diffusion effect is high even when the light beam 95d is irradiated. As a result, the light beam 95d reaching the wall surface of the casing 107 is diffused and does not affect the image. As described above, the light blocking member 201a is inclined with respect to the direction of the rotation axis of the rotary polygon mirror 41 so that the light beam 95c deflected by the rotary polygon mirror 41 and reflected by the lens 400a does not go toward the photosensitive drum 50M. There is. In the present embodiment, the inclination is 12.2°.

In summary, when the light blocking members 201a and 201b are made of metal, the light beams reflected by the lenses 400a and 400b may be further reflected by the light blocking members 201a and 201b. Therefore, by tilting the light blocking member 201a and the light blocking member 201b with respect to the direction of the rotation axis of the rotary polygon mirror 41, so-called flare light can be prevented from traveling toward the photosensitive drum. As a matter of course, even when the light blocking member 201a and the light blocking member 201b are members made of resin, if the reflectance of the laser light on the surface is high enough to generate flare light, as described above, the light blocking is performed. It can be said that inclining the member 201a and the light blocking member 201b with respect to the direction of the rotation axis of the rotary polygon mirror 41 is effective.

1 Image forming apparatus 40 Optical scanning device 41 Rotating polygonal mirror 43Y lens 43M lens 43C lens 43Bk lens 60a Light beam 61a Light source unit 61b Light source unit 70a Light beam 71a Light source unit 71b Light source unit 101 Bottom 105 Optical box 106 Cover 107 Housing 201a Shading Member 201b Light-shielding member 230a Mounting part 230b Mounting part 220F Opening 220R Opening 400a Lens 400b Lens

Claims (22)

A metal housing,
A first light source that emits a first light beam;
A second light source for emitting a second light beam;
The first light beam and the second light beam, which are installed on the bottom of the housing and rotate about a rotation axis and are incident obliquely with respect to the direction of the rotation axis, are opposite to each other with the rotation axis interposed therebetween. A rotating polygon mirror that deflects to the side,
A first lens for guiding the first light beam deflected by the rotating polygon mirror to a first photosensitive drum;
A second lens for guiding the second light beam deflected by the rotating polygon mirror to a second photosensitive drum;
The first light beam deflected by the rotary polygon mirror is reflected by the first lens toward the second lens, and the bottom portion is located with respect to the rotary polygon mirror in the direction of the rotation axis. Is attached to the housing so as to be positioned on the optical path of the reflected light of the first light beam that has passed through the side opposite to the side, and the reflected light of the first light beam is directed to the second photosensitive drum. A light blocking member that blocks the reflected light of the first light beam so that
The optical scanning device, wherein the light shielding member and the housing are separate bodies. The optical scanning device according to claim 1, wherein the light blocking member is located between the rotary polygon mirror and the second lens. The optical scanning device according to claim 1, wherein the light blocking member blocks the reflected light of the first light beam that has passed through the second lens. The optical scanning device according to any one of claims 1 to 3, wherein the light shielding member is made of resin. The optical scanning device according to any one of claims 1 to 3, wherein the light blocking member is made of metal. The light shielding member is made of metal and is attached between the rotary polygon mirror and the second lens,
The light shielding member attached to the housing is inclined with respect to the direction of the rotation axis, and the second light beam reflected by the second lens is prevented from being directed to the second photosensitive drum. The optical scanning device according to claim 1, wherein the reflected light of the second light beam is reflected. A third lens through which the light beam of the first light beam that has passed through the first lens passes,
The light blocking member is configured so that the light beam of the first light beam that is reflected by the first lens and then further reflected by the light blocking member passes through the outside of the third lens in the direction of the rotation axis. The optical scanning device according to claim 6, wherein the optical scanning device is inclined with respect to the direction of the rotation axis. The housing has a first mounting portion to which one end side of the light shielding member is mounted and a second mounting portion to which the other end side of the light shielding member is mounted, and both the first mounting portion and the second mounting portion are provided. Both are inclined with respect to the direction of the rotation axis, and a reflection surface of the light blocking member for reflecting the second light beam is inclined with respect to the direction of the rotation axis. The optical scanning device according to claim 6 or claim 7. The housing has a first mounting portion to which one end side of the light shielding member is mounted and a second mounting portion to which the other end side of the light shielding member is mounted, and the reflected light of the second light beam of the light shielding member. Of the light-shielding member is inclined with respect to a direction perpendicular to a contact surface contacting the first mounting portion and a direction perpendicular to a contact surface contacting the second mounting portion, The optical scanning device according to claim 6, wherein the reflection surface is inclined with respect to the direction of the rotation axis. The first mounting portion and the second mounting portion are projections provided so as to project from the bottom of the housing,
In the second light beam deflected by the rotating polygon mirror, the light blocking member is attached to the first attachment portion and the second attachment portion, and the bottom portion, the first attachment portion, and the second attachment are attached. 10. The optical scanning device according to claim 8, wherein the optical scanning device passes through an opening formed by being surrounded by a portion and the light shielding member. The optical scanning device according to any one of claims 1 to 10, wherein the light shielding member and the housing are bonded with an adhesive. A first light source that emits a first light beam;
A second light source for emitting a second light beam;
A rotary polygon mirror that rotates around a rotation axis and that deflects the first light beam and the second light beam that are obliquely incident with respect to the direction of the rotation axis to opposite sides with the rotation axis interposed therebetween. ,
A first lens for guiding the first light beam deflected by the rotating polygon mirror to a first photosensitive drum;
A second lens for guiding the second light beam deflected by the rotating polygon mirror to a second photosensitive drum;
An opening is formed through which the second light beam deflected by the rotary polygon mirror and directed toward the second photosensitive drum is formed, and
The first light beam deflected by the rotating polygon mirror is reflected by the first lens toward the second lens, and passes through the outside of the rotating polygon mirror in the direction of the rotation axis. On the optical path of the reflected light of the light beam of, the area outside the opening is located, and the reflected light of the first light beam that has passed the outside of the rotary polygon mirror in the direction of the rotation axis is A light blocking member for blocking the reflected light of the first light beam so as not to go to the second photosensitive drum;
A metal housing that accommodates the rotary polygon mirror, the first lens, the second lens, and the light blocking member, and is provided with a mounting portion to which the light blocking member is attached. ,
An optical scanning device, wherein the light shielding member and the housing are separate bodies. The optical scanning device according to claim 12, wherein the light blocking member is attached to the attachment portion between the rotary polygon mirror and the second lens. 13. The optical scanning device according to claim 12, wherein the light blocking member blocks the reflected light of the first light beam that has passed through the second lens. 15. The optical scanning device according to claim 12, wherein the light blocking member is made of resin. 15. The optical scanning device according to claim 12, wherein the light blocking member is made of metal. The light shielding member is made of metal and is attached to the attachment portion between the rotary polygon mirror and the second lens,
The light shielding member attached to the attaching portion is inclined with respect to the direction of the rotation axis, and the second light beam that passes through the opening and is reflected by the second lens is the second photosensitive drum. 13. The optical scanning device according to claim 12, wherein the second light beam is reflected so that it does not go to. A third lens through which the light beam of the first light beam that has passed through the first lens passes,
The light blocking member is configured so that the light beam of the first light beam that is reflected by the first lens and then further reflected by the light blocking member passes through the outside of the third lens in the direction of the rotation axis. The optical scanning device according to claim 17, wherein the optical scanning device is inclined with respect to the direction of the rotation axis. 19. The optical scanning device according to claim 17, wherein the mounting portion has a surface on which the light shielding member is mounted, and the surface is inclined with respect to the direction of the rotation axis. The mounting portion has a surface to which the light shielding member is mounted, and a reflection surface of the light shielding member for reflecting the reflected light of the second light beam is different from a contact surface of the light shielding member in contact with the surface. 19. The optical scanning device according to claim 17, wherein the optical scanning device is inclined with respect to a vertical direction. The optical scanning device according to any one of claims 12 to 20, wherein the light shielding member and the mounting portion are bonded with an adhesive. The first photosensitive drum and the second photosensitive drum,
The first photosensitive drum is irradiated with the first light beam to form an electrostatic latent image, and the second photosensitive drum is irradiated with the second light beam to form an electrostatic latent image. An optical scanning device according to any one of claims 1 to 21;
Developing means for developing the electrostatic latent image formed by the optical scanning device with toner;
An image forming apparatus comprising: a transfer unit that transfers the toner image formed by the developing unit onto a recording sheet.

Images