JP2007156150A - Image forming apparatus - Google Patents

Abstract

An image forming apparatus capable of suppressing the formation of an abnormal image by obtaining synchronization of deflection scanning of laser light with higher accuracy than the conventional one.
An image forming apparatus includes a polygon mirror that deflects and scans laser light, and a light receiving device 30 that detects the laser light deflected and scanned by the polygon mirror in order to obtain synchronization of the deflection scanning of the laser light by the polygon mirror. The light receiving device 30 includes a light receiving element 32 having a light receiving portion 32a for detecting laser light, and a passage hole 34a through which the laser light to be detected by the light receiving portion 32a passes, and a portion other than the passage hole 34a. And a light blocking member 34 that blocks the laser beam, and the passage hole 34a is formed only in a range that is part of a range facing the light receiving element 32 and includes a range facing the light receiving portion 32a.
[Selection] Figure 4

Description

  The present invention relates to an image forming apparatus such as a laser printer, a digital copying machine, and a facsimile machine equipped with a writing optical system that simultaneously records a plurality of lines using a plurality of recording light sources that can be independently modulated.

As a conventional image forming apparatus, an image forming apparatus that forms an image on a photosensitive drum by deflecting and scanning a laser beam modulated in accordance with an image signal generated from a laser diode by a polygon mirror. 2. Description of the Related Art An image forming apparatus that obtains synchronization of laser beam deflection scanning based on a detection signal from a light receiving element disposed at a position in front of an effective writing region is known.
JP 2002-67382 A

  However, in the conventional image forming apparatus, there are cases where laser light is reflected by a member other than the light receiving portion of the light receiving element and is incident on the light receiving portion. There was a problem of forming.

  The present invention has been made to solve the conventional problems, and provides an image forming apparatus capable of suppressing abnormal image formation by obtaining synchronization of deflection scanning of laser light with higher accuracy than before. The purpose is to do.

  The image forming apparatus of the present invention includes a deflection scanning unit that deflects and scans a laser beam and the laser beam deflected and scanned by the deflection scanning unit to obtain synchronization of the deflection scanning of the laser beam by the deflection scanning unit. A light receiving device for detecting the laser light, and a light receiving element having a light receiving portion for detecting the laser light, and a passage hole through which the laser light to be detected by the light receiving portion is passed. And a light blocking member that blocks the laser beam at a portion other than the hole, and the passage hole is formed only in a range including a range facing the light receiving portion and a part of the range facing the light receiving element. It has a configuration.

  With this configuration, the image forming apparatus according to the present invention suppresses the laser light that has passed through the passage hole of the light blocking member from entering the portion other than the light receiving unit. It can suppress that the laser beam reflected in parts other than enters into a light-receiving part. For example, the image forming apparatus of the present invention suppresses the laser light that has passed through the passage hole of the light blocking member from entering the frame of the light receiving element, so that the laser light is incident on the frame of the light receiving element and the surface state of the frame Then, after being reflected by the shape, it can be prevented that the light is irregularly reflected by the interface of the package of the light receiving element or the surface of the package and incident on the light receiving portion. Therefore, the image forming apparatus of the present invention can suppress erroneous detection of the unexpected laser beam by the light receiving unit, so that it is possible to obtain synchronization of deflection scanning of the laser beam with higher accuracy than in the past. The formation of an image can be suppressed as compared with the conventional case.

  The light blocking member of the image forming apparatus according to the present invention has a configuration in which the portion closer to the light receiving element is closer to the light receiving element as the portion is closer to the passage hole.

  With this configuration, the image forming apparatus according to the present invention reflects the laser light that has passed through the passage hole of the light blocking member and reflected from a portion other than the light receiving portion in a direction away from the light receiving portion at the light receiving element side portion of the light blocking member. Therefore, it is possible to suppress the laser light that has passed through the passage hole of the light blocking member and entered the portion other than the light receiving portion from entering the light receiving portion. For example, in the image forming apparatus of the present invention, even if laser light is incident on a printed wiring board to which a light receiving element is attached and reflected by the surface state or color tone of the printed wiring board, the laser light reflected by the printed wiring board is light. Since the light is reflected in the direction away from the light receiving portion at the light receiving element side portion of the blocking member, it is possible to suppress the laser light entering the printed wiring board from passing through the passage hole of the light blocking member from entering the light receiving portion. it can. Therefore, the image forming apparatus of the present invention suppresses the light receiving unit from erroneously detecting unexpected laser light, that is, laser light that has passed through the passage hole of the light blocking member and entered the portion other than the light receiving unit. Therefore, it is possible to obtain laser beam deflection scanning synchronization with higher accuracy and further suppress abnormal image formation.

  Further, the light blocking member of the image forming apparatus of the present invention has a configuration in which the portion where the passage hole is closer to the light receiving element is smaller.

  With this configuration, in the image forming apparatus of the present invention, the laser light incident on the portion of the light blocking member that forms the passage hole is reflected in the direction away from the light receiving portion at the portion of the light blocking member that forms the passage hole. Therefore, it can suppress that the laser beam which injected into the part which forms a passage hole among light blocking members enters into a light-receiving part. Therefore, the image forming apparatus according to the present invention can prevent the light receiving unit from erroneously detecting an unexpected laser beam, that is, a laser beam incident on a portion of the light blocking member that forms the passage hole. Synchronization of laser beam deflection scanning can be obtained with higher accuracy, and abnormal image formation can be further suppressed.

  Further, the light receiving device of the image forming apparatus of the present invention includes a printed wiring board to which the light receiving element is attached, and the light blocking member has a configuration including a fixing portion that fixes itself to the printed wiring board. is doing.

  With this configuration, in the image forming apparatus of the present invention, the light blocking member is directly fixed to the printed wiring board without any other component such as a screw. The light blocking member and the printed wiring board can be positioned with high accuracy as compared with the configuration fixed via the light receiving member. As a result, the light blocking member and the light receiving element attached to the printed wiring board Can be positioned with high accuracy. Therefore, the image forming apparatus of the present invention can further suppress the erroneous detection of the unexpected laser beam by the light receiving unit, so that the synchronization of the laser beam deflection scanning can be obtained with higher accuracy, Image formation can be further suppressed. Further, in the image forming apparatus of the present invention, the light blocking member is directly fixed to the printed wiring board without using other components such as screws. Compared to the fixed configuration, the dimensional tolerance of each part can be widened, so that the manufacturing cost can be reduced by manufacturing with a low-priced part having a wide dimensional tolerance.

  The present invention can provide an image forming apparatus capable of suppressing the formation of an abnormal image as compared with the prior art by obtaining synchronization of deflection scanning of laser light with higher accuracy than the prior art.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
First, the configuration of the image forming apparatus according to the first embodiment will be described.

  As shown in FIGS. 1 and 2, the image forming apparatus according to the present embodiment includes a laser diode 11 that emits laser light, a printed wiring board 12 that controls the emission of laser light by the laser diode 11, and a laser diode. A collimating lens 13 that converts the laser light emitted by the light 11 into parallel light, an aperture 14 that performs beam shaping of the laser light that has passed through the collimating lens 13, and a cylindrical that compresses the laser light that has passed through the aperture 14 in the sub-scanning direction. The lens 15, a reflection mirror 16 that reflects the laser light that has passed through the cylindrical lens 15, a polygon mirror 17 that serves as a deflection scanning unit that deflects and scans the laser light reflected by the reflection mirror 16, and occurs when the polygon mirror 17 rotates. The surrounding dust adheres to the polygon mirror 17 due to the airflow. The polygon mirror protective glass 18 that prevents the above, the fθ lenses 19 and 20 that adjust the position and shape of the laser light that has been deflected and scanned by the polygon mirror 17 and passed through the polygon mirror protective glass 18, and the fθ lenses 19 and 20 Barrel toroidal lens 21 that uniformizes the pitch of laser light, dust-proof glass 22 that prevents toner from adhering to various optical components, and a photosensitive drum on which a latent image is formed on the surface by laser light and toner is adhered. 23, a drum mirror 24 that reflects the laser light that has passed through the barrel toroidal lens 21 and passed through the dust-proof glass 22 toward the photosensitive drum 23, and a polygon in order to synchronize the deflection scanning of the laser light by the polygon mirror 17. A light receiving device 30 for detecting the laser beam deflected and scanned by the mirror 17; Eteiru.

  As shown in FIG. 3 and FIG. 4, the light receiving device 30 detects a laser beam and a housing portion 31 in which a passage hole 31 a through which laser light passes is formed and blocks the laser light at a portion other than the passage hole 31 a. A light receiving element 32 having a light receiving part 32a, a printed wiring board 33 to which the light receiving element 32 is attached, and a passage hole 34a through which a laser beam to be detected by the light receiving part 32a is formed. Are provided with a light blocking member 34 for blocking the laser beam, and a set screw 35 for fixing the printed wiring board 33 and the light blocking member 34 to the housing portion 31.

  Here, the housing portion 31 is formed with a screw hole (not shown), a projection 31b that is screwed with the set screw 35, and a pin 31c for positioning the printed wiring board 33 and the light blocking member 34. 31d.

  The light receiving element 32 includes a frame 32b that is a wiring of the light receiving portion 32a, and a package 32c enclosing the light receiving portion 32a and the frame 32b.

  Further, the printed wiring board 33 is formed with a long hole 33a into which the set screw 35 is inserted and a hole 33b into which the pin 31c is inserted.

  The light blocking member 34 has a hole 34b into which the set screw 35 is inserted and a hole 34c into which the pin 31c is inserted. The passage hole 34a is formed only in a part of the range facing the light receiving element 32 and including the range facing the light receiving part 32a.

  Next, a method for manufacturing the light receiving device 30 will be described.

  First, the light receiving element 32 is attached to the printed wiring board 33.

  Then, after the pins 31 c of the housing portion 31 are sequentially inserted into the holes 34 c of the light blocking member 34 and the holes 33 b of the printed wiring board 33, the set screws 35 are elongated holes 33 a of the printed wiring board 33 and the light blocking members 34. The housing portion 31, the printed wiring board 33, and the light blocking member 34 are positioned and fixed to each other by being sequentially inserted into the holes 34b and screwed into the protrusions 31b of the housing portion 31.

  Next, the operation of the image forming apparatus according to the present embodiment will be described.

  In the image forming apparatus according to the present embodiment, the laser beam emitted from the laser diode 11 is deflected and scanned by the polygon mirror 17 to reach the photosensitive drum 23 and the light receiving device 30.

  In the image forming apparatus according to the present embodiment, the laser light is detected by the light receiving device 30 to obtain the synchronization of the deflection scanning of the laser light by the polygon mirror 17, and the image writing position on the photosensitive drum 23 is adjusted. To do.

  Then, the image forming apparatus according to the present embodiment forms a latent image on the surface of the photosensitive drum 23 based on the adjusted writing position by using a laser beam, and attaches toner to the surface of the photosensitive drum 23. The toner attached to the surface of the photosensitive drum 23 is transferred to the printing paper.

  Here, the laser beam deflected and scanned by the polygon mirror 17 reaches the light receiving device 30 as shown by a locus 30a shown in FIG. 3, passes through the passage hole 31a of the housing portion 31 as shown by a locus 30b, and passes the locus 30c. As described above, the light passes through the passage hole 34 a of the light blocking member 34 and is detected by the light receiving portion 32 a of the light receiving element 32. That is, in the light receiving device 30, the passage hole 34a is formed only in a part of the range facing the light receiving element 32 and including the range facing the light receiving part 32a. Therefore, the passage hole 34a of the light blocking member 34 is formed. The light blocking member 34 prevents the laser light that has passed through from entering the portion other than the light receiving portion 32a.

  As described above, the image forming apparatus according to the present embodiment suppresses the laser light that has passed through the passage hole 34a of the light blocking member 34 from entering the portion other than the light receiving unit 32a. It is possible to suppress the laser light that has passed through the passage hole 34a of 34 and reflected by a portion other than the light receiving portion 32a from entering the light receiving portion 32a. For example, the image forming apparatus according to the present embodiment suppresses the laser light that has passed through the passage hole 34 a of the light blocking member 34 from entering the frame 32 b of the light receiving element 32. After being incident on 32b and reflected by the surface state and shape of the frame 32b, it is possible to suppress the irregular reflection due to dirt on the interface of the package 32c of the light receiving element 32 or the surface of the package 32c and the incident on the light receiving portion 32a. it can. Accordingly, the image forming apparatus according to the present embodiment can suppress erroneous detection of unexpected laser light by the light receiving unit 32a, and therefore, synchronization of laser beam deflection scanning can be obtained with higher accuracy than before. Thus, abnormal image formation can be suppressed as compared with the prior art.

(Second Embodiment)
First, the configuration of the image forming apparatus according to the second embodiment will be described.

  Note that, in the configuration of the image forming apparatus according to the present embodiment, the same configuration as the configuration of the image forming apparatus according to the first embodiment is the same as the configuration of the image forming apparatus according to the first embodiment. Detailed description will be omitted.

  The configuration of the image forming apparatus according to this embodiment is a light receiving device that detects laser light deflected and scanned by the polygon mirror 17 in order to obtain synchronization of laser beam deflection scanning by the polygon mirror 17 (see FIG. 1). 40 (see FIG. 5) is the same as the configuration of the image forming apparatus according to the first embodiment instead of the light receiving device 30 (see FIG. 4).

  As shown in FIG. 5, the configuration of the light receiving device 40 includes a light blocking member 44 that is formed with a passage hole 34a through which laser light to be detected by the light receiving unit 32a passes and blocks the laser light at portions other than the passage hole 34a. Is the same as the configuration of the light receiving device 30 instead of the light blocking member 34 (see FIG. 4).

  The light blocking member 44 is the same as the light blocking member 34 except that the portion closer to the light receiving element 32 (hereinafter referred to as “element side portion”) 44a is closer to the light receiving element 32 as the portion closer to the passage hole 34a. is there.

  Next, the operation of the image forming apparatus according to the present embodiment will be described.

  Of the operations of the image forming apparatus according to the present embodiment, detailed descriptions of operations similar to those of the image forming apparatus according to the first embodiment are omitted.

  Since the light receiving device 40 is closer to the light receiving element 32 as the element side portion 44a of the light blocking member 44 is closer to the passage hole 34a, the portion other than the light receiving portion 32a passes through the passage hole 34a of the light blocking member 44. The laser beam reflected at is reflected by the element side portion 44a of the light blocking member 44 in a direction away from the light receiving portion 32a. For example, as shown in FIG. 6, the light receiving device 40 is configured such that even if laser light is incident on the printed wiring board 33 to which the light receiving element 32 is attached and reflected by the surface state or color tone of the printed wiring board 33, The laser beam reflected by 33 is reflected by the element side portion 44a of the light blocking member 44 in a direction away from the light receiving unit 32a.

  As described above, in the image forming apparatus according to the present embodiment, the laser light that passes through the passage hole 34a of the light blocking member 44 and is reflected by the portion other than the light receiving portion 32a is the element side portion of the light blocking member 44. 44a is reflected in a direction away from the light receiving part 32a, and therefore, it is possible to prevent the laser light that has passed through the passage hole 34a of the light blocking member 44 and entered the part other than the light receiving part 32a from entering the light receiving part 32a. it can. For example, in the image forming apparatus according to the present embodiment, even if laser light is incident on the printed wiring board 33 to which the light receiving element 32 is attached and reflected by the surface state or color tone of the printed wiring board 33, the printed wiring board 33. Since the laser light reflected by the light is reflected by the element side portion 44a of the light blocking member 44 in the direction away from the light receiving portion 32a, the laser light that has entered the printed wiring board 33 through the passage hole 34a of the light blocking member 44 is reflected. It can suppress entering into the light-receiving part 32a. Therefore, in the image forming apparatus according to the present embodiment, the light receiving unit 32a erroneously receives unexpected laser light, that is, laser light that has passed through the passage hole 34a of the light blocking member 44 and is incident on a portion other than the light receiving unit 32a. Since the detection can be suppressed, compared with the image forming apparatus according to the first embodiment, laser beam deflection scanning synchronization can be obtained with higher accuracy, and abnormal image formation can be further achieved. Can be suppressed.

  The laser light that passes through the passage hole 34a of the light blocking member 44, is reflected by a portion other than the light receiving portion 32a, and is reflected by the element side portion 44a of the light blocking member 44 is the element side portion of the light receiving element 32 with respect to the light receiving portion 32a. The closer the traveling direction is to the incident direction of the incident position on 44a, the farther away from the light receiving portion 32a, the better. Therefore, the inclination of the element side portion 44a of the light blocking member 44 is preferably determined from that viewpoint.

(Third embodiment)
First, the configuration of the image forming apparatus according to the third embodiment will be described.

  Note that, in the configuration of the image forming apparatus according to the present embodiment, the same configuration as the configuration of the image forming apparatus according to the first embodiment is the same as the configuration of the image forming apparatus according to the first embodiment. Detailed description will be omitted.

  The configuration of the image forming apparatus according to this embodiment is a light receiving device that detects laser light deflected and scanned by the polygon mirror 17 in order to obtain synchronization of laser beam deflection scanning by the polygon mirror 17 (see FIG. 1). 50 (see FIG. 7) is the same as the configuration of the image forming apparatus according to the first embodiment instead of the light receiving device 30 (see FIG. 4).

  As shown in FIG. 7, the configuration of the light receiving device 50 includes a light blocking member 54 that is formed with a passage hole 54a through which the laser light to be detected by the light receiving unit 32a passes and blocks the laser light at a portion other than the passage hole 54a. Is the same as the configuration of the light receiving device 30 instead of the light blocking member 34 (see FIG. 4).

  The configuration of the light blocking member 54 is the same as the configuration in which a smaller passage hole 54a is formed in the light blocking member 34 in place of the passage hole 34a (see FIG. 4) as the portion is closer to the light receiving element 32.

  Next, the operation of the image forming apparatus according to the present embodiment will be described.

  Of the operations of the image forming apparatus according to the present embodiment, detailed descriptions of operations similar to those of the image forming apparatus according to the first embodiment are omitted.

  As shown in FIG. 8, in the light receiving device 50, the portion where the passage hole 54 a of the light blocking member 54 is closer to the light receiving element 32 is smaller. The laser beam incident on the hole forming portion 54b is reflected by the hole forming portion 54b in a direction away from the light receiving portion 32a.

  As described above, in the image forming apparatus according to the present embodiment, the laser light incident on the hole forming portion 54b is reflected in the direction away from the light receiving portion 32a by the hole forming portion 54b. The incident laser light can be prevented from entering the light receiving part 32a. Therefore, the image forming apparatus according to the present embodiment can prevent the light receiving unit 32a from erroneously detecting unexpected laser light, that is, laser light incident on the hole forming portion 54b. Compared with the image forming apparatus according to the embodiment, the laser beam deflection scanning synchronization can be obtained with higher accuracy, and the formation of an abnormal image can be further suppressed.

  The laser beam reflected by the hole forming portion 54b is more preferable because it is farther from the light receiving portion 32a as the traveling direction is closer to the direction of the incident position on the hole forming portion 54b with respect to the light receiving portion 32a of the light receiving element 32. Therefore, the inclination of the hole forming portion 54b of the light blocking member 54 is preferably determined from that viewpoint.

(Fourth embodiment)
First, the configuration of the image forming apparatus according to the fourth embodiment will be described.

  Note that, in the configuration of the image forming apparatus according to the present embodiment, the same configuration as the configuration of the image forming apparatus according to the first embodiment is the same as the configuration of the image forming apparatus according to the first embodiment. Detailed description will be omitted.

  The configuration of the image forming apparatus according to this embodiment is a light receiving device that detects laser light deflected and scanned by the polygon mirror 17 in order to obtain synchronization of laser beam deflection scanning by the polygon mirror 17 (see FIG. 1). 60 (see FIG. 9) is the same as the configuration of the image forming apparatus according to the first embodiment instead of the light receiving device 30 (see FIG. 4).

  As shown in FIG. 9, the structure of the light receiving device 60 is such that a printed wiring board 63 to which a light receiving element 32 is attached and a through hole 34a through which a laser beam to be detected by the light receiving unit 32a passes are formed. The light blocking member 64 that blocks the laser beam at other portions is the same as the configuration provided in the light receiving device 30 in place of the printed wiring board 33 (see FIG. 4) and the light blocking member 34 (see FIG. 4). is there.

  The configuration of the light blocking member 64 is the same as the configuration in which the light blocking member 34 includes a claw portion 64a as a fixing portion for fixing the light blocking member 64 to the printed wiring board 63 instead of the holes 34b and 34c (see FIG. 4). .

  The configuration of the printed wiring board 63 is the same as the configuration in which the hole 63 a into which the claw portion 64 a of the light blocking member 64 is inserted is formed in the printed wiring board 33.

  Next, a method for manufacturing the light receiving device 60 will be described.

  First, the light receiving element 32 is attached to the printed wiring board 63.

  Next, the light blocking member 64 is positioned and fixed to the printed wiring board 63 by inserting and bending the claw portion 64 a of the light blocking member 64 that is not yet bent into the hole 63 a of the printed wiring board 63.

  Then, after the pin 31c of the housing portion 31 is inserted into the hole 33b (see FIG. 3) of the printed wiring board 63, the set screw 35 is inserted into the long hole 33a (see FIG. 3) of the printed wiring board 63. Thus, the housing 31 and the printed wiring board 63 are positioned and fixed to each other by being screwed into the protrusion 31 b of the housing 31.

  As described above, in the image forming apparatus according to the present embodiment, since the light blocking member 64 is directly fixed to the printed wiring board 63 without passing through other components such as the set screw 35, the light blocking member 34. Compared to the image forming apparatus according to the first embodiment in which the light blocking member 64 and the printed wiring board 63 are fixed to the printed wiring board 33 through other components such as a set screw 35, the light blocking member 64 and the printed wiring board 63 are highly accurate. As a result, the passage hole 34a of the light blocking member 64 and the light receiving portion 32a of the light receiving element 32 attached to the printed wiring board 63 can be positioned with high accuracy. Therefore, the image forming apparatus according to the present embodiment can further suppress erroneous detection of the unexpected laser beam by the light receiving unit 32a, as compared with the image forming apparatus according to the first embodiment. Therefore, laser beam deflection scanning synchronization can be obtained with higher accuracy, and abnormal image formation can be further suppressed.

  Further, in the image forming apparatus according to the present embodiment, the light blocking member 64 is directly fixed to the printed wiring board 63 without any other components such as the set screw 35, so that the light blocking member 34 is the printed wiring board 33. Compared with the image forming apparatus according to the first embodiment, which is fixed through other parts such as the set screw 35, the dimensional tolerance of each part can be widened. Manufacturing cost can be reduced by manufacturing with simple parts.

(Fifth embodiment)
A configuration of an image forming apparatus according to the fifth embodiment will be described.

  Note that, in the configuration of the image forming apparatus according to the present embodiment, the same configuration as the configuration of the image forming apparatus according to the second embodiment is the same as the configuration of the image forming apparatus according to the second embodiment. Detailed description will be omitted.

  The configuration of the image forming apparatus according to this embodiment is a light receiving device that detects laser light deflected and scanned by the polygon mirror 17 in order to obtain synchronization of laser beam deflection scanning by the polygon mirror 17 (see FIG. 1). 70 (see FIG. 10) is the same as the configuration of the image forming apparatus according to the second embodiment instead of the light receiving device 40 (see FIG. 5).

  As shown in FIG. 10, the configuration of the light receiving device 70 includes a light blocking member 74 that has a passage hole 74a through which laser light to be detected by the light receiving unit 32a passes and blocks the laser light at portions other than the passage hole 74a. Is the same as the configuration of the light receiving device 40 instead of the light blocking member 44 (see FIG. 5).

  The configuration of the light blocking member 74 is the same as the configuration in which a smaller passage hole 74a is formed in the light blocking member 44 in place of the passage hole 34a (see FIG. 5) as the portion is closer to the light receiving element 32.

  The image forming apparatus according to the present embodiment can obtain the operational effects of the image forming apparatus according to the second embodiment and the operational effects of the image forming apparatus according to the third embodiment.

(Sixth embodiment)
A configuration of the image forming apparatus according to the sixth embodiment will be described.

  Note that, in the configuration of the image forming apparatus according to the present embodiment, the same configuration as the configuration of the image forming apparatus according to the second embodiment is the same as the configuration of the image forming apparatus according to the second embodiment. Detailed description will be omitted.

  The configuration of the image forming apparatus according to this embodiment is a light receiving device that detects laser light deflected and scanned by the polygon mirror 17 in order to obtain synchronization of laser beam deflection scanning by the polygon mirror 17 (see FIG. 1). 80 (see FIG. 11) is the same as the configuration of the image forming apparatus according to the second embodiment instead of the light receiving device 40 (see FIG. 5).

  As shown in FIG. 11, the configuration of the light receiving device 80 includes a printed wiring board 83 to which the light receiving element 32 is attached and a through hole 34a through which the laser light to be detected by the light receiving unit 32a is passed. The light blocking member 84 that blocks the laser beam at other portions is the same as the configuration of the light receiving device 40 in place of the printed wiring board 33 (see FIG. 5) and the light blocking member 44 (see FIG. 5). is there.

  The configuration of the light blocking member 84 is similar to the configuration in which the light blocking member 44 includes a claw portion 84a as a fixing portion for fixing the light blocking member 84 to the printed wiring board 83 instead of the holes 34b and 34c (see FIG. 5). .

  The configuration of the printed wiring board 83 is the same as the configuration in which the hole 83 a into which the claw portion 84 a of the light blocking member 84 is inserted is formed in the printed wiring board 33.

  The image forming apparatus according to the present embodiment can obtain the operational effects of the image forming apparatus according to the second embodiment and the operational effects of the image forming apparatus according to the fourth embodiment.

(Seventh embodiment)
The configuration of the image forming apparatus according to the seventh embodiment will be described.

  Note that, in the configuration of the image forming apparatus according to the present embodiment, the same configuration as the configuration of the image forming apparatus according to the sixth embodiment is the same as the configuration of the image forming apparatus according to the sixth embodiment. Detailed description will be omitted.

  The configuration of the image forming apparatus according to this embodiment is a light receiving device that detects laser light deflected and scanned by the polygon mirror 17 in order to obtain synchronization of laser beam deflection scanning by the polygon mirror 17 (see FIG. 1). 90 (see FIG. 12) is the same as the configuration provided in the image forming apparatus according to the sixth embodiment instead of the light receiving device 80 (see FIG. 11).

  As shown in FIG. 12, the configuration of the light receiving device 90 includes a light blocking member 94 that is formed with a passage hole 94a through which laser light to be detected by the light receiving unit 32a passes and blocks the laser light at portions other than the passage hole 94a. Is the same as the configuration of the light receiving device 80 instead of the light blocking member 84 (see FIG. 11).

  The configuration of the light blocking member 94 is the same as the configuration in which a smaller passage hole 94a is formed in the light blocking member 84 in place of the passage hole 34a (see FIG. 4) as it is closer to the light receiving element 32.

  The image forming apparatus according to the present embodiment is the same as that of the image forming apparatus according to the second embodiment, the function and effect of the image forming apparatus according to the third embodiment, and the fourth embodiment. The effect of the image forming apparatus can be obtained.

1 is a top view of an image writing unit of an image forming apparatus according to a first embodiment of the present invention. The perspective view of the image writing part shown in FIG. 1 is an exploded perspective view of the light receiving device of the image writing unit shown in FIG. Top view of the light receiving device shown in FIG. Top view of a light-receiving device according to a second embodiment of the present invention Top view of the vicinity of the light receiving element of the light receiving device shown in FIG. Top view of a light receiving device according to a third embodiment of the present invention Top view of the vicinity of the light receiving element of the light receiving device shown in FIG. The top view of the light-receiving device based on the 4th Embodiment of this invention Top view of a light-receiving device according to a fifth embodiment of the present invention The top view of the light-receiving device based on the 6th Embodiment of this invention Top view of a light-receiving device according to a seventh embodiment of the present invention

Explanation of symbols

17 Polygon mirror (deflection scanning means)
DESCRIPTION OF SYMBOLS 30 Light receiving device 32 Light receiving element 32a Light receiving part 34 Light blocking member 34a Passing hole 40 Light receiving device 44 Light blocking member 44a Element side part (light receiving element side part)
DESCRIPTION OF SYMBOLS 50 Light receiving device 54 Light shielding member 54a Passing hole 60 Light receiving device 63 Printed wiring board 64 Light shielding member 64a Claw part (fixing part)
Reference Signs List 70 light receiving device 74 light blocking member 74a passage hole 80 light receiving device 83 printed circuit board 84 light blocking member 84a claw portion (fixed portion)
90 light receiving device 94 light blocking member 94a passage hole

Claims (4)

A deflection scanning means for deflecting and scanning the laser light; and a light receiving device for detecting the laser light deflected and scanned by the deflection scanning means to obtain synchronization of the deflection scanning of the laser light by the deflection scanning means;
The light receiving device includes a light receiving element having a light receiving portion for detecting the laser light, and a passage hole through which the laser light to be detected by the light receiving portion is formed. And a light blocking member for blocking
The image forming apparatus according to claim 1, wherein the passage hole is formed only in a range that is a part of a range facing the light receiving element and includes a range facing the light receiving unit. The image forming apparatus according to claim 1, wherein the light blocking member is closer to the light receiving element as a portion closer to the passage hole is closer to the light receiving element. The image forming apparatus according to claim 1, wherein the light blocking member is smaller as a portion where the passage hole is closer to the light receiving element. The light receiving device includes a printed wiring board to which the light receiving element is attached,
The image forming apparatus according to claim 1, wherein the light blocking member includes a fixing portion that fixes the light blocking member to the printed wiring board.

Images