JP2008168472A - Optical scanner and image forming apparatus having it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanner, the inside of which can be efficiently cooled. <P>SOLUTION: In a casing 70, a rotating polygon mirror 74 is arranged in such a manner as to lean to the side A. In other words, the rotating polygon mirror 74 is arranged in such a manner as to satisfy the inequality: L1<L2. In the inequality, L1 represents a distance between the center of the rotation of the rotating polygon mirror 74 and a side-A inner wall of the casing 70, and L2 represents a distance between the center of the rotation of the rotating polygon mirror 74 and a side-B inner wall of the casing 70. On a substrate 80, a rotating-polygon-mirror rotation control IC 76 is arranged on the side B with respect to the rotating polygon mirror 74. Additionally, in the casing 70, an fθ lens 78 is arranged in such a manner as to lean to the side A. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

For example, Patent Document 1 discloses an optical device that cools a driver bar IC using wind generated by a polygon mirror being rotationally driven.
Patent Document 2 discloses an optical scanning device in which a flow path for circulating an air flow generated by a rotating polygon mirror is formed in an optical box, and heat generation of the entire optical box can be reduced.

JP-A-11-202246 JP 2000-267037 A

  The present invention has been made from the background described above, and an object thereof is to provide an optical scanning device capable of efficiently cooling the inside of the device.

  In order to achieve the above object, an optical scanning device according to the present invention includes a rotation reflection member that reflects light while rotating, a transmission lens that transmits light reflected by the rotation reflection member, and rotation of the rotation reflection member. A rotation reflection member control means for controlling the rotation reflection member, and a housing that rotatably supports the rotation reflection member and accommodates the rotation reflection member, the transmission lens, and the rotation reflection member control means. The rotation reflection member control means is disposed on the side where the rotation reflection member rotates away from the rotation reflection member as viewed from the transmission lens side.

  Preferably, the distance between the inner wall of the casing on the side where the rotary reflection member approaches and rotates when viewed from the transmission lens side and the rotation center of the rotation reflection member is the rotation when viewed from the transmission lens side. The distance is smaller than the distance between the inner wall of the casing on the side where the reflecting member rotates away from the rotation center of the rotating reflecting member.

  Preferably, the width of the front side of the casing when viewed from the transmission lens side from the transmission lens side is larger than the width of the other side when viewing the rotation reflection member side from the transmission lens side. Has been.

  Preferably, the distance between the transmission lens and the inner wall of the housing on the side where the rotary reflecting member approaches and rotates when viewed from the transmission lens side is the transmission lens and the distance when viewed from the transmission lens side. It is smaller than the interval with the inner wall of the casing on the side where the rotary reflecting member rotates away.

Preferably, it further includes an air flow reflecting means for reflecting an air flow generated by the rotation of the rotary reflecting member in the direction of the rotary reflecting member control means,
The rotary reflecting member control means is cooled by the airflow reflected by the airflow reflecting means.

  The present invention includes an image forming apparatus having the above-described optical scanning device.

  According to the optical scanning device of the present invention, the rotary reflection member control means is disposed on the side where the rotary reflection member rotates away from the transmission lens side with respect to the rotary reflection member. Can be cooled.

Embodiments of the present invention will be described below.
FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention.

  The image forming apparatus 10 includes an image forming apparatus main body 12, an image forming unit 14 is mounted in the image forming apparatus main body 12, and a discharge unit 16 is provided on the upper portion of the image forming apparatus main body 12. A paper feed unit 18 is disposed below the image forming apparatus main body 12. In addition, a sheet conveyance path 17 for conveying sheets is formed in the image forming apparatus main body 12, and the sheet conveyance path 17 has a reverse path 50 as a conveyance path for double-sided printing described later.

  The paper feed unit 18 has a paper feed cassette 20, paper feed rolls 22 a, 22 b, and a separating roll 23, in which a sheet as a transfer material is stored and which can be pulled out from the image forming apparatus main body 12. The paper loaded in the paper feed cassette 20 is separated and fed to the registration roll 24 by the cooperation of the paper roll 22b and the separating roll 23.

  On the downstream side of the registration roll 24, an image carrier 28 and a transfer device 36 of a process cartridge (developing cartridge) 46, which will be described later, face each other, and a fixing device 40 is further provided on the downstream side thereof.

  Accordingly, the sheet fed from the sheet feeding cassette 20 of the sheet feeding unit 18 to the sheet conveying path 17 by the sheet feeding rolls 22a and 22b is temporarily stopped by the registration roll 24, and the image carrier 28 and the transfer device are timed. The developer image is transferred through the space 36, the transferred developer image is fixed by the fixing device 40, and discharged to the discharge portion 16 by the discharge roll 26.

  However, in the case of duplex printing, it is returned to the duplex printing unit 48 as duplex printing means. That is, the double-sided printing unit 48 is divided into two forks before the discharge roll 26, and a switching claw (not shown) is provided in the divided part, and double-sided printing returning from the divided part to the resist roll 24. A reverse path 50 is formed as a transfer path. The reversing path 50 is provided with transport rolls 52a to 52c. In double-sided printing, a switching claw (not shown) is switched to the side that opens the reversing path 50, and the discharge roll 26 is in front of the rear end of the sheet. At this time, the discharge roll 26 is reversed, the sheet is guided to the reverse path 50, and is discharged to the discharge portion 16 through the resist roll 24, the transfer device 36 and the image carrier 28 and through the fixing device 40.

The image forming means 14 is of an electrophotographic type, and includes an image carrier 28 made of a photoconductor, a charging device 30 made of, for example, a charging roll for uniformly charging the image carrier 28, and charging by the charging device 30. An optical writing device 32 that writes a latent image on the image carrier 28 by light, a developing device 34 that visualizes a latent image of the image carrier 28 formed by the optical writing device 32, and a developing device 34 For example, a transfer device 36 that transfers the developer image onto the paper, a cleaning device 38 that cleans the developer remaining on the image carrier 28, and a developer image on the paper transferred by the transfer device 36 is fixed on the paper. The fixing device 40 includes a pressure roll and a heating roll.
The optical writing device 32 is composed of, for example, a scanning laser exposure device, and traverses the process cartridge 46 to form a latent image on the image carrier 28.
The optical writing device 32 may use an LED or a surface emitting laser as another embodiment.

  In the process cartridge 46, the image carrier 28, the charging device 30, the developing device 34, and the cleaning device 38 are integrated, and these can be replaced as a unit.

  The paper feed cassette 20 described above is provided with a paper transport path 60. When a plurality of paper cassettes are arranged in multiple stages by this paper transport path 60, paper fed from other paper feed cassettes arranged on the lower side is transported.

  Further, a manual feed unit 54 as a manual paper feed unit is disposed on a side surface (left side surface in FIG. 1) of the image forming apparatus main body 12. The manual feed unit 54 includes a manual feed tray 56 for storing paper and a manual pick roll 58, and the paper stored in the manual feed tray 56 is picked by the rotation of the manual feed pick roll 58. The paper fed from the manual pick roll 58 is discharged between the registration roll 24, the transfer device 36 and the image carrier 28, and the fixing device 40, as in the paper fed from the paper feeding unit 18. To be discharged.

A manual feed tray 56 provided in the manual feed unit 54 opens when it rotates in the direction of the arrow shown in FIG. 1 and is supported by the image forming apparatus main body 12 so that it can be opened and closed.
The manual feed tray 56 is provided with a side guide 62 and a manual feed roll 64. The side guide 62 is movably provided in accordance with the size of the paper so as to contact the side surface of the paper stored in the manual feed tray 56. The manual feed roll 64 is disposed at a position facing the manual feed roll 58, and the paper stored in the manual feed tray 56 is separated and fed by the cooperation of the manual feed roll 64 and the manual feed roll 58. It has become.

FIG. 2 shows details of the optical writing device 32.
The optical writing device 32 includes a housing 70, a light source 72, a rotary polygon mirror 74, a rotary polygon mirror rotation control IC 76 that controls the rotation of the rotary polygon mirror 74, and fθ lenses 78a and 78b.
Inside the housing 70, a rotary polygon mirror 74, a rotary polygon mirror rotation control IC 76, and fθ lenses 78a and 78b are arranged. The rotary polygon mirror 74 and the rotary polygon mirror rotation control IC 76 are supported by the substrate 80 and supported by the housing 70 via the substrate 80.

The light source 72 is disposed outside the housing 70, and the laser light emitted from the light source 72 passes through a through hole provided in the housing 70 and is reflected by the rotating polygon mirror 74.
The rotary polygon mirror 74 is mounted on a shaft 82, and the shaft 82 is rotatably supported on the substrate 80 via a bearing 84.
Further, the rotary polygon mirror 74 has, for example, six deflection surfaces (mirror surfaces), and rotates the laser light in the direction of arrow R (shown in FIG. 2) at a predetermined equiangular speed by a motor (not shown) while the fθ lens 78a, Reflects towards 78b.
The laser light reflected by the rotary polygon mirror 74 is transmitted through the fθ lenses 78a and 78b, thereby scanning the image area on the image carrier 28 at a substantially constant speed in the main scanning direction.
Note that when any of a plurality of components is shown without being specified, such as the fθ lenses 78a and 78b, the fθ lens 78 may be simply abbreviated.

Here, as shown in FIG. 2, the side on which the rotary polygon mirror 74 approaches and rotates when viewed from the fθ lens 78 side is rotated on the A side, and the side on which the rotary polygon mirror 74 is rotated away from the fθ lens 78 side is rotated. Let it be the side. Further, the substrate 80 side with respect to the fθ lens 78 is the C side, and the fθ lens 78 side with respect to the substrate 80 is the D side.
The rotary polygon mirror 74 is arranged in the housing 70 so as to be offset toward the A side. That is, assuming that the distance between the rotation center of the rotating polygon mirror 74 and the inner wall on the A side of the housing 70 is L1, and the distance between the rotation center of the rotating polygon mirror 74 and the inner wall on the B side of the housing 70 is L2, The mirror 74 is arranged so that L1 <L2.
The rotary polygon mirror rotation control IC 76 is disposed on the B side with respect to the rotary polygon mirror 74 on the substrate 80.

Furthermore, the fθ lens 78 is arranged in the housing 70 so as to be offset toward the A side.
That is, if the interval between the fθ lens 78a and the inner wall on the A side of the casing 70 is M1, and the interval between the fθ lens 78a and the inner wall on the B side of the casing 70 is M2, the fθ lens 78a satisfies M1 <M2. Are arranged as follows.
Similarly, when the interval between the fθ lens 78b and the inner wall on the A side of the housing 70 is M3, and the distance between the fθ lens 78b and the inner wall on the B side of the housing 70 is M4, the fθ lens 78b is M3 <M4. It is arranged to be.

In the case 70, as shown in FIG. 2, when the width of the inner wall on the substrate 80 side (C side) is W1, and the width of the inner wall on the fθ lens 78 side (D side) is W2, the case 70 has W1 < It is formed to be W2.
Further, as shown in FIG. 2, a part 70 a of the inner wall 70 a on the A side and a part 70 b of the inner wall B side of the housing 70 are arranged so that the airflow described later smoothly flows in the direction of the substrate 80. It is formed obliquely toward the center.

Hereinafter, the operation of the embodiment will be described with reference to FIGS.
In FIG. 3, the air flow generated inside the optical writing device 32 in the above embodiment is shown. The airflow is indicated by arrow F.
The airflow generated by the rotation of the rotary polygon mirror 74 moves from the vicinity of the A side of the rotary polygon mirror 74 to the D side. A part of the airflow directed toward the D side hits the fθ lens 78.
Of the airflow directed toward the D side, the airflow that did not hit the fθ lens 78 passes above and below the fθ lens 78 and hits the inner wall on the D side.

Since the fθ lens 78 is arranged so that M1 <M2 and M3 <M4, the distance between the fθ lens 78 and the inner wall of the housing 70 is wider on the B side than on the A side. Gas tends to flow toward the B side. Therefore, the airflow hitting the inner wall on the D side is directed to the B side.
The airflow that hits the inner wall on the D side and heads toward the B side hits the inner wall on the B side, and travels along the inner wall 70b toward the rotating polygon mirror rotation control IC 76 on the C side.
The airflow that hits the fθ lens 78 travels toward the B side, merges with the airflow toward the rotary polygon mirror rotation control IC 76 along the inner wall on the B side, and travels toward the rotary polygon mirror rotation control IC 76.

Since the bearing 84 and the rotary polygon mirror rotation control IC 76 that rotatably support the rotary polygon mirror 74 generate heat, the temperature on the D side is lower than the temperature on the C side. Therefore, since the gas that hits the fθ lens 78 and the inner wall on the D side and returns to the C side is cooled on the D side, the temperature of the returned gas is in the vicinity of the rotating polygon mirror 74 that is the source of the air flow and the rotating polygon. It is lower than the ambient temperature near the mirror rotation control IC 76.
For this reason, the bearing 84 of the rotary polygon mirror 74 and the rotary polygon mirror rotation control IC 76 are cooled by the gas generated by the rotation of the rotary polygon mirror 74, sent to the D side, reflected, and returned from the D side.
In addition, since the fθ lens 78 is arranged closer to the A side and the airflow space is made larger on the B side, the flow rate of the gas cooled on the D side can be increased. Therefore, the bearing 84 of the rotary polygon mirror 74 and the rotary polygon mirror rotation control IC 76 can be cooled more efficiently.

FIG. 4 shows the airflow inside the optical writing device 32 when the position of the fθ lens 78 is moved (arrangement X).
The fθ lens 78 is arranged so that M1> M2 and M3> M4.

The airflow generated by the rotation of the rotary polygon mirror 74 moves from the vicinity of the A side of the rotary polygon mirror 74 to the D side. A part of the airflow directed toward the D side hits the fθ lens 78.
Of the airflow directed toward the D side, the airflow that did not hit the fθ lens 78 passes above and below the fθ lens 78 and hits the inner wall on the D side.

Since the fθ lens 78 is arranged so that M1> M2 and M3> M4, the distance between the fθ lens 78 and the inner wall of the housing 70 is wider on the A side, and thus the A side is larger. The gas is easy to flow in the direction. Therefore, most of the airflow hitting the inner wall on the D side is directed to the A side.
The airflow that hits the inner wall on the D side and heads toward the A side hits the inner wall on the A side and travels toward the substrate 80 on the C side along the inner wall 70a.
The airflow that hits the fθ lens 78 travels toward the A side, merges with the airflow toward the C-side substrate 80 along the inner wall on the A-side, and travels toward the substrate 80.

Here, the airflow toward the substrate 80 is prevented from advancing by the airflow generated at the position P by the rotation of the rotary polygon mirror 74 and toward the D side. Therefore, the airflow that has progressed to the D side and has been cooled is difficult to reach the substrate 80.
Therefore, the airflow that cools the bearing 84 and the rotary polygon mirror rotation control IC 76 that generate heat on the substrate 80 is reflected toward the D-side and slightly returned along the inner wall on the B-side, and the fθ lens 78a. Only the airflow returned.
Therefore, the above embodiment can cool the bearing 84 of the rotary polygon mirror 74 and the rotary polygon mirror rotation control IC 76 more efficiently than the arrangement X shown in FIG.

FIG. 5 shows the airflow inside the optical writing device 32 when the position of the rotary polygon mirror 74 and the position of the rotary polygon mirror rotation control IC 76 are reversed (arrangement Y).
The rotary polygon mirror 74 is arranged such that L1> L2, and the rotary polygon mirror rotation control IC 76 is arranged on the A side with respect to the rotary polygon mirror 74.
The airflow generated by the rotation of the rotary polygon mirror 74 is directed to the rotary polygon mirror rotation control IC 76. The airflow toward the rotary polygon mirror rotation control IC 76 is directed toward the D side, reflected on the fθ lens 78 and the inner wall on the D side, and returns toward the substrate 80 on the C side.

Here, most of the airflow passing through the rotary polygon mirror rotation control IC 76 is generated by the rotation of the rotary polygon mirror 74 and is directly directed to the rotary polygon mirror rotation control IC 76. Therefore, this airflow does not contribute to efficient cooling of the rotary polygon mirror rotation control IC 76. Therefore, the said embodiment can implement | achieve efficient cooling compared with the arrangement | positioning Y shown in FIG.
Further, the airflow that is directed to the D side, reflected by the fθ lens 78 and the inner wall on the D side and returning toward the substrate 80 is generated by the rotation of the rotary polygon mirror 74 and then passes through the vicinity of the rotary polygon mirror rotation control IC 76. In addition, the temperature of the gas rises. Therefore, the above embodiment can realize efficient cooling as compared with the arrangement Y shown in FIG.

FIG. 6 is a diagram showing a comparison between the temperature of each part in the above embodiment and the temperature of each part in another arrangement.
As shown in FIG. 6, the temperature of each part in the said embodiment is a result lower than other arrangement | positioning. In other words, the above-described embodiment can achieve more efficient cooling.

As described above, the optical writing device 32 according to the embodiment of the present invention does not directly apply the airflow generated by the rotation of the rotary polygon mirror 74 to the rotary polygon mirror rotation control IC 76 but sends it to the fθ lens 78 side. Since the rotating polygon mirror rotation control IC 76 and the like are cooled by the cooled airflow, efficient cooling can be realized.
Further, since the optical writing device 32 according to the embodiment of the present invention can realize efficient cooling without forming a special flow path, the size of the device is increased in order to cool the internal device having a large calorific value. And cost increase can be avoided.

The number of fθ lenses is two in the above description, but may be any number.
In addition, the devices that generate heat in the optical writing device are the bearings of the rotary polygon mirror and the rotary polygon mirror rotation control IC. However, any device may be used, for example, a capacitor or the like may be disposed.
Further, although the light source 72 is disposed outside the housing 70, it may be disposed inside.

1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating an optical writing device in an image forming apparatus according to an embodiment of the present invention. It is a figure which shows the airflow which generate | occur | produces inside the optical writing device which concerns on embodiment of this invention. It is a figure which shows the airflow which generate | occur | produces in the optical writing device at the time of moving the position of ftheta lens. It is a figure which shows the airflow which generate | occur | produces in the optical writing device at the time of reversing the position of a rotary polygon mirror, and the position of a rotary polygon mirror rotation control IC. It is a figure which shows the comparison with the temperature of each part in the optical writing device which concerns on embodiment of this invention, and the temperature of each part in other arrangement | positioning.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming apparatus main body 14 Image forming means 32 Optical writing apparatus 70 Case 72 Light source 74 Rotating polygon mirror 76 Rotating polygon mirror rotation control IC
78 fθ lens 80 substrate 84 bearing

Claims (6)

A rotating reflecting member that reflects light while rotating;
A transmission lens that transmits the light reflected by the rotary reflection member;
Rotation reflection member control means for controlling rotation of the rotation reflection member;
A housing that rotatably supports the rotating reflecting member, and that houses the rotating reflecting member, the transmission lens, and the rotating reflecting member control means;
The rotation reflection member control means is an optical scanning device which is arranged on the side where the rotation reflection member is rotated away from the rotation reflection member when viewed from the transmission lens side. The distance between the inner wall of the casing on the side where the rotary reflection member approaches and rotates when viewed from the transmission lens side and the rotation center of the rotation reflection member are separated from the rotation reflection member when viewed from the transmission lens side. The optical scanning device according to claim 1, wherein the optical scanning device is smaller than a distance between an inner wall of the casing on the rotating side and a rotation center of the rotary reflecting member. The width of the front side of the casing when viewed from the transmission lens side from the transmission lens side is larger than the width of the side from the transmission lens side when viewed from the rotation reflection member side. Item 3. The optical scanning device according to Item 1 or 2. The distance between the transmission lens and the inner wall of the housing on the side where the rotary reflection member approaches and rotates when viewed from the transmission lens side is such that the rotation reflection member is viewed from the transmission lens and the transmission lens side. The optical scanning device according to any one of claims 1 to 3, wherein the optical scanning device is smaller than a distance from an inner wall of the housing on the side that rotates away. An airflow reflecting means for reflecting the airflow generated by the rotation of the rotating reflecting member in the direction of the rotating reflecting member control means;
The optical scanning device according to any one of claims 1 to 4, wherein the rotation reflection member control unit is cooled by an airflow reflected by the airflow reflection unit.   An image forming apparatus comprising the optical scanning device according to claim 1.

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