JP5163584B2 - Optical scanning device - Google Patents

Description

  The present invention relates to an optical scanning device, and more particularly to an optical scanning device used in an image forming apparatus.

  As a conventional optical scanning device, for example, a scanning optical device used in the image forming apparatus described in Patent Document 1 is known. The scanning optical device will be described below with reference to the drawings. FIG. 6 is a configuration diagram of the scanning optical device 200 described in Patent Document 1. In FIG.

  As shown in FIG. 6, the scanning optical apparatus 200 includes a housing 202, a deflector 204, scanning lenses 206 and 208, and a mirror 210. The deflector 204 deflects the beam B. The scanning lenses 206 and 208 correct the aberration of the deflected beam B. The mirror 210 reflects the beam B that has passed through the scanning lenses 206 and 208 and guides it outside the scanning optical apparatus 200. The housing 202 stores the deflector 204, the scanning lenses 206 and 208, and the mirror 210.

  The housing 202 is provided with an air flow path R100. As shown in FIG. 6, the flow path R100 extends under the deflector 204 and the scanning lenses 206 and 208.

  In the scanning optical device 200 configured as described above, air flows in the direction indicated by the arrow in FIG. At this time, the air cools the deflector 204 by removing heat from the deflector 204. Further, the air passes under the mirror 210 and flows out of the housing 202.

  Incidentally, the scanning optical device 200 has a problem that the optical elements such as the scanning lenses 206 and 208 are heated. More specifically, the deflector 204 releases heat from the substrate and the bearing portion during operation. Therefore, the air that has passed under the deflector 204 is heated. Here, the scanning lenses 206 and 208 are provided on the downstream side of the deflector 204 in the flow path R100. Therefore, the scanning lenses 206 and 208 are expanded by being heated by the air heated by the deflector 204 and cannot exhibit their original optical characteristics. As a result, there is a possibility that position shift or focus shift may occur in the formed image.

JP 2004-294949 A

  Accordingly, an object of the present invention is to provide an optical scanning device capable of suppressing the deterioration of the optical performance of an optical element due to heat.

An optical scanning device according to an aspect of the present invention is an optical scanning device used in an image forming apparatus, and includes a light source that emits a beam, a light source unit that includes an optical element that refracts or reflects the beam, and deflects the beam. A first flow path in which the light source section is adjacent, and the deflection means. A flow path formed by connecting a second flow path adjacent to each other in series is provided in the housing, and the first flow path is provided upstream of the second flow path. The flow rate in the first flow path is larger than the flow speed in the second flow path .

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the optical performance of an optical element deteriorates with a heat | fever.

1 is a schematic perspective view of an optical scanning device according to an embodiment of the present invention. It is the figure which planarly viewed the optical scanning device of FIG. It is an external appearance perspective view of the optical scanning device of FIG. It is an external appearance perspective view of the optical scanning device of FIG. FIG. 5A is a model diagram showing a flow path of the optical scanning device of FIG. FIG. 5B is a model diagram illustrating a flow path of the optical scanning device according to the comparative example. 1 is a configuration diagram of a scanning optical device described in Patent Document 1. FIG.

  The optical scanning device according to the embodiment of the present invention will be described below.

(Optical scanning device)
First, an outline of an optical scanning device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of an optical scanning device 10 according to an embodiment of the present invention. The optical scanning device 10 roughly includes a housing 12, a light source 14Y, a collimator lens 15Y, a cylindrical lens 16, a deflector 17, scanning lenses 18, 20Y, a folding mirror 22Y, and a dustproof glass 24Y. Installed. In FIG. 1, only the light source 14Y, the collimator lens 15Y, the folding mirror 22Y, and the dustproof glass 24Y are used for Y (yellow) image formation. However, actually, the light sources 14Y, 14M, 14C, and 14K corresponding to the four colors Y (yellow), M (magenta), C (cyan), and K (black), the collimator lenses 15Y, 15M, 15C, and 15K, Scanning lenses 20Y, 20M, 20C, and 20K, folding mirrors 22Y, 22M, 22C, and 22K and dustproof glasses 24Y, 24M, 24C, and 24K are provided.

  The light source 14Y is constituted by a laser diode and emits a beam B. The beam B is converted into parallel light by the collimator lens 15Y, and is imaged by the cylindrical lens 16 so as to be linear on the reflecting surface of the deflector 17. The deflector 17 is composed of a polygon mirror and a motor, and deflects the beam B in the main scanning direction at a constant angular velocity. The scanning lenses 18 and 20 correct the aberration of the deflected beam B. The folding mirror 22Y reflects the beam B toward the photosensitive drum 50Y. The beam B reflected by the folding mirror 22Y passes through the dust-proof glass 24Y and forms an image on the photosensitive drum 50Y. The photosensitive drum 50Y is rotationally driven at a predetermined speed. A two-dimensional image (electrostatic latent image) is formed by the main scanning by the beam B and the sub-scanning by the rotation of the photosensitive drum 50Y. The housing 12 stores a light source 14Y, a collimator lens 15Y, a cylindrical lens 16, a deflector 17, scanning lenses 18 and 20, a folding mirror 22Y, and a dustproof glass 24Y.

  Next, a specific configuration of the optical scanning device 10 will be described with reference to the drawings. FIG. 2 is a plan view of the optical scanning device 10. FIG. 2 shows the optical scanning device 10 with the lid removed. 3 and 4 are external perspective views of the optical scanning device 10. In FIG. 3, a part of the optical scanning device 10 is cut to show the inside of the optical scanning device 10. FIG. 4 shows the optical scanning device 10 with the lid removed. 2 to 4, the main scanning direction is defined as the y-axis direction, the sub-scanning direction is defined as the z-axis direction, and the direction perpendicular to the y-axis direction and the z-axis direction (the traveling direction of the beam B) is the x-axis direction. It is defined as

  As shown in FIGS. 2 to 4, the housing 12 is composed of a main body 12a and a lid 12b. As shown in FIG. 1, the main surfaces S1 and S2 and side surfaces S3 to S6 (the side surface S6 is not shown). )). As shown in FIGS. 2 and 4, the main body 12 a is a rectangular parallelepiped box that is open on the positive side in the z-axis direction, and includes a main surface S <b> 2 and side surfaces S <b> 3 to S <b> 6. The lid 12b closes the opening of the main body 12a and constitutes the main surface S1. The main body 12a is made of, for example, a resin. The lid 12b is made of sheet metal, for example. The main surface S1 and the main surface S2 are located opposite to each other in the z-axis direction, the side surface S3 and the side surface S6 are located opposite to each other in the x-axis direction, and the side surface S4 and the side surface are opposed to each other. S5 is located opposite to both ends in the y-axis direction.

  The housing 12 is divided into two regions, an element region E and a flow path R, as shown in FIGS. Specifically, the housing 12 has a partition wall 40. As shown in FIGS. 2 to 4, the partition wall 40 extends in the y-axis direction parallel to the side surface S3 at a position away from the side surface S3 by a predetermined distance. The partition 40 connects the side surface S4 and the side surface S5, and also connects the main surface S1 and the main surface S2. Thereby, as shown in FIGS. 2 and 4, the inside of the housing 12 is divided into an element region E and a flow path R. The partition wall 40 is provided by standing a resin rib on the main surface S2 of the main body 12a.

  The flow path R is a space through which air for cooling the deflector 17 flows, and is provided in the housing 12 so as to extend along the side surface S3 as shown in FIGS. Specifically, the flow path R is formed so as to extend in the y-axis direction by being surrounded by the main surface S1, the intermediate wall 42, the side surface S3, and the partition wall 40. That is, the main surface S1, the intermediate wall 42, the side surface S3, and the partition wall 40 constitute a wall surface of the flow path R. Here, as shown in FIG. 3, the intermediate wall 42 is a plate-like member provided in parallel with the main surfaces S1 and S2 between the main surface S1 and the main surface S2. Further, an opening O1 is provided in the vicinity of the side surface S3 of the side surface S5. Further, an opening O2 is provided in the vicinity of the side surface S3 of the side surface S4.

  The flow path R is formed by connecting a flow path R1 and a flow path R2 in series as shown in FIGS. The flow path R1 is provided on the upstream side of the flow path R2 (that is, the negative direction side in the y-axis direction). As shown in FIG. 3, the height H1 of the flow path R1 in the z-axis direction is lower than the height H2 of the flow path R2 in the z-axis direction. Thereby, the cross-sectional area of the flow path R1 is smaller than the cross-sectional area of the flow path R2. As a result, the flow rate in the flow path R1 is larger than the flow rate in the flow path R2.

  Further, the light source unit 30 is adjacent to the flow path R1. Specifically, as illustrated in FIG. 2, the light source unit 30 is provided on the negative direction side of the intermediate wall 42 in the z-axis direction so as to overlap the flow path R1 when viewed in plan from the z-axis direction. . The light source unit 30 includes light sources 14Y, 14M, 14C, and 14K, collimator lenses 15Y, 15M, 15C, and 15K, a cylindrical lens 16, and a mirror (not shown) that reflects the beam B. The collimator lenses 15Y, 15M, 15C, and 15K, the cylindrical lens 16, and the mirror (not shown) that reflects the beam B constitute an optical element.

  Further, the deflector 17 is adjacent to the flow path R2. Specifically, as shown in FIG. 2, the deflector 17 is provided on the negative direction side of the intermediate wall 42 in the z-axis direction so as to overlap the flow path R <b> 2 when viewed in plan from the z-axis direction. . Accordingly, the deflector 17 is located downstream of the light source unit 30 in the flow path R (that is, the positive direction side in the y-axis direction).

  Furthermore, a heat radiating member 32 is provided in the flow path R2. As shown in FIGS. 2 to 4, the heat radiating member 32 is manufactured by bending a single metal plate into a U-shape. And the heat radiating member 32 has the upstream part 32a and the downstream part 32b. The upstream portion 32a is provided on the upstream side of the downstream portion 32b (that is, the negative direction side in the y-axis direction). Further, the width W1 of the upstream portion 32a in the x-axis direction is narrower than the width W2 of the downstream portion 32b in the x-axis direction.

  The element region E is located on the positive direction side of the flow path R in the x-axis direction when viewed in plan from the z-axis direction. As shown in FIGS. 2 to 4, the element region E has scanning lenses 18, 20Y, 20M, 20C, and 20K (scanning lenses 20M, 20C, and 20K) that refract, transmit, or reflect the beam B deflected by the deflector 17. ), Folding mirrors 22Y, 22M, 22C, and 22K (folding mirrors 22M, 22C, and 22K are not shown) and dustproof glasses 24Y, 24M, 24C, and 24K are provided. Thereby, as shown in FIG. 2, the scanning lenses 18, 20Y, 20M, 20C, 20K, the folding mirrors 22Y, 22M, 22C, 22K and the dustproof glasses 24Y, 24M, 24C, 24K It is not provided between S3 and flow path R1. That is, the scanning lenses 18, 20Y, 20M, 20C, and 20K, the folding mirrors 22Y, 22M, 22C, and 22K, and the dustproof glasses 24Y, 24M, 24C, and 24K are opposite to the side surface S3 in the casing 12 with respect to the flow path R1. Is located.

  In the optical scanning device 10 as described above, air flows into the flow path R from the opening O1, and air flows out of the flow path R from the opening O2. At this time, the air passing through the flow path R <b> 1 comes into contact with the intermediate wall 42 to remove heat from the intermediate wall 42, thereby cooling the light source unit 30. Further, the air passing through the flow path R <b> 2 comes into contact with the heat radiating member 32, and the heat from the heat radiating member 32 is taken away, whereby the deflector 17 is cooled. The air flow is generated by a fan (not shown) provided in the image forming apparatus.

(effect)
In the optical scanning device 10 as described above, the optical performance of the collimator lens 15Y and the cylindrical lens 16 can be prevented from being deteriorated by heat, as will be described below. More specifically, the collimator lens 15Y and the cylindrical lens 16 are likely to expand under the influence of heat. Then, when the collimator lens 15Y and the cylindrical lens 16 are expanded, the optical performance of the collimator lens 15Y and the cylindrical lens 16 is deteriorated, and an image position shift or a focus shift occurs.

  Therefore, in the optical scanning device 10, the light source unit 30 in which the collimator lens 15 </ b> Y and the cylindrical lens 16 are stored is provided upstream of the deflector 17 in the flow path R. Thereby, the light source unit 30 is cooled by the air before being heated by the deflector 17. As a result, the light source unit 30 is effectively cooled, and the collimator lens 15Y and the cylindrical lens 16 are suppressed from being heated. Therefore, in the optical scanning device 10, deterioration of the optical performance of the collimator lens 15Y and the cylindrical lens 16 is suppressed.

  Further, in the optical scanning device 10, it is possible to suppress deterioration of the optical performance of the collimator lens 15 </ b> Y and the cylindrical lens 16 due to heat also for the reason described below. FIG. 5A is a model diagram showing the flow path R of the optical scanning device 10. FIG. 5B is a model diagram showing the flow path R ′ of the optical scanning device according to the comparative example.

  In the optical scanning device shown in FIG. 5B, the flow path R ′ is composed of the flow path R1 ′ and the flow path R2 ′. The cross-sectional area of the flow path R1 ′ is equal to the cross-sectional area of the flow path R2 ′. Further, the flow velocity V1 ′ in the flow path R1 ′ is equal to the flow velocity V2 ′ in the flow path R2 ′. Therefore, in the optical scanning device, there is a possibility that air flows backward as indicated by the dotted line in FIG. 5B, and the heat of the deflector 17 ′ is transmitted to the light source unit 30 ′.

  On the other hand, in the optical scanning device 10 shown in FIG. 5A, the flow path R is composed of the flow path R1 and the flow path R2. The cross-sectional area of the flow path R1 is smaller than the cross-sectional area of the flow path R2. Furthermore, the flow velocity V1 in the flow path R1 is larger than the flow velocity V2 in the flow path R2. Therefore, in the optical scanning device 10, it is difficult for air to flow backward from the flow path R2 to the flow path R1. As a result, the heat of the deflector 17 is not easily transmitted to the light source unit 30. Therefore, in the optical scanning device 10, it is possible to effectively suppress deterioration of the optical performance of the collimator lens 15Y and the cylindrical lens 16 due to heat.

  Moreover, the optical scanning device 10 can suppress the optical performance of the scanning lenses 18 and 20, the folding mirrors 22Y, 22M, 22C, and 22K and the dustproof glasses 24Y, 24M, 24C, and 24K from being deteriorated by heat. More specifically, in the optical scanning device 10, between the flow path R and the side surface S3, there are scanning lenses 18, 20, folding mirrors 22Y, 22M, 22C, 22K and dustproof glasses 24Y, 24M, 24C, 24K. do not do. As a result, the scanning lenses 18 and 20, the folding mirrors 22Y, 22M, 22C, and 22K and the dustproof glasses 24Y, 24M, 24C, and 24K are present only on the positive side in the x-axis direction with respect to the flow path R. . Therefore, in the optical scanning device 10, the scanning lenses 18 and 20, the folding mirrors 22Y, 22M, 22C, and 22K and the dust-proof glasses 24Y, 24M, 24C, and 24K are mainly heated by the heat released from the intermediate wall 42. . In the optical scanning device 10, the optical performance of the scanning lenses 18 and 20, the folding mirrors 22Y, 22M, 22C, and 22K and the dustproof glasses 24Y, 24M, 24C, and 24K can be suppressed from being deteriorated by heat.

  Furthermore, in the optical scanning device 10, the optical performance of the scanning lenses 18 and 20, the folding mirrors 22Y, 22M, 22C, and 22K and the dustproof glasses 24Y, 24M, 24C, and 24K is suppressed from being deteriorated due to heat for the following reasons. it can. More specifically, in the optical scanning device 10, the flow path R is composed of the main surface S 1, the intermediate wall 42, the side surface S 3, and the partition wall 40. Therefore, of the four wall surfaces forming the flow path R, two wall surfaces (the main surface S1 and the side surface S3) are part of the housing 12 and are exposed to the outside. As a result, of the heat released from the flow path R, the heat released via the main surface S1 and the side surface S3 is directly released outside the optical scanning device 10. Therefore, the amount of heat staying in the optical scanning device 10 is relatively small. As a result, in the optical scanning device 10, the optical performance of the scanning lenses 18 and 20, the folding mirrors 22Y, 22M, 22C, and 22K and the dustproof glasses 24Y, 24M, 24C, and 24K can be prevented from being deteriorated by heat.

  In the optical scanning device 10, the cross-sectional areas of the flow paths R1 and R2 are adjusted by the heights H1 and H2. However, the cross-sectional areas of the flow path cross-sectional areas R1 and R2 may be adjusted by the width in the x-axis direction.

  In the optical scanning device 10, the heat radiating member 32 may not be provided.

  The present invention is useful for an optical scanning device, and is particularly excellent in that the optical performance of an optical element can be prevented from being deteriorated by heat.

E element region O1, O2 opening R, R1, R2 flow path S1, S2 main surface S3 to S6 side surface 10 optical scanning device 12 housing 12a main body 12b lid 14C, 14K, 14M, 14Y light source 15C, 15K, 15M, 15Y collimator Lens 16 Cylindrical lens 17 Deflector 18, 20C, 20K, 20M, 20Y Scan lens 22C, 22K, 22M, 22Y Folding mirror 24C, 24K, 24M, 24Y Dust-proof glass 30 Light source part 32 Heat radiation member 32a Upstream part 32b Downstream part 40 Bulkhead 42 Middle wall

Claims (2)

In an optical scanning device used in an image forming apparatus,
A light source that emits a beam, and a light source unit that includes an optical element that refracts or reflects the beam;
Deflection means for deflecting the beam;
A housing housing the light source unit and the deflecting means;
With
A flow path through which air flows, wherein a first flow path adjacent to the light source unit and a second flow path adjacent to the deflecting means are connected in series, is the housing. Provided in the body,
The first flow path, provided we are on the upstream side of the second flow path,
The flow rate in the first channel is greater than the flow rate in the second channel;
An optical scanning device characterized by the above. The cross-sectional area of the first flow path is smaller than the cross-sectional area of the second flow path;
The optical scanning device according to claim 1 .

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