JP2009086483A - Scanning optical unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scanning optical unit, further easily and efficiently ensuring sealing property in a housing, and reducing deterioration of optical performance due to distortion or the like caused when the unit is mounted on an image forming apparatus or the like. <P>SOLUTION: The scanning optical unit comprises a housing having a reference surface on which a scanning optical system is disposed, and a flexible cover part having an opening for emitting a luminous flux to the outside and mounted on the housing from the side opposed to the reference surface. An end surface opposed to the cover part in a holding frame which holds an optical element located closest to the emitting side in the scanning optical system is located on substantially the same plane as an edge surface to which the cover part is mounted in the housing. The cover part is mounted on the housing by being adhered to the edge surface and the end surface of the holding frame while aligning the opening with a space regulated by the end surface of the holding frame, whereby the inside of the housing is sealed by the cover member, the holding frame and the optical element. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a scanning optical unit including a scanning optical system for scanning a laser beam on a predetermined surface to be scanned.

  A conventional scanning optical unit includes a box-shaped housing main body, a scanning optical system housed in the housing main body, and a cover portion attached to the housing. Such a scanning optical unit is disclosed, for example, in Patent Document 1 below. In the following text, for convenience, a surface on which each optical member is attached in the housing is defined as a reference surface. In general, it is often the bottom that each optical member is attached in the housing. Therefore, unless otherwise specified in the text, the bottom surface is assumed to be the reference surface of the housing, and the cover portion is assumed to close the opening on the side facing the bottom surface, which is the reference surface.

JP 2000-137184 A

  In recent years, there has been a desire to make an image forming apparatus equipped with such a scanning optical unit multifunctional or downsized. In order to meet this demand, the scanning optical unit may be configured so that laser light through the scanning optical system is emitted to the outside through an irradiation window provided in the cover portion. In such a configuration, a cover glass is attached to the irradiation window in addition to the above configuration in order to prevent dust and the like from entering the irradiation window.

  In conventional scanning optical units, it is known that if dust, dust, or the like is mixed inside, there is a risk of damaging the deflecting surface of a deflector such as a polygon mirror or reducing the reflectivity of the deflecting surface. For this reason, the cover portion is attached to the housing while maintaining hermeticity so that dust or the like does not enter the housing from the outside. For example, the cover portion is screwed with a sealing member such as urethane foam interposed between the cover portion and the housing. Further, the cover glass is also attached to the cover portion via the sealing member so as to ensure adhesion. Further, the cover portion in the conventional scanning optical unit is often made of a highly rigid sheet metal or resin flat plate suitable for firm screwing.

  However, in the case of such a conventional configuration, the following problems are pointed out. That is, first, in the conventional configuration, it is necessary to attach a sealing member such as urethane foam with high precision along the cover part mounting surface in the housing and the irradiation window in the cover part. Therefore, the installation work becomes very complicated and the efficiency is poor. The cover mounting surface means a surface substantially parallel to the bottom surface of the side wall disposed along the outer periphery of the bottom surface of the housing (hereinafter referred to as an edge surface for the sake of convenience in the description). Therefore, the more complicated the outer peripheral shape of the housing, the greater the burden on the cover mounting operation.

  Second, when the scanning optical unit is attached to the image forming apparatus, a certain load generated in the unit may affect the optical performance of the scanning optical system disposed inside the housing. Specifically, the load should be properly absorbed due to the distortion of the housing body. However, when the cover portion having high rigidity as described above is used, it is difficult to absorb the load by the housing body, and unintended distortion may occur in the scanning optical system disposed inside the housing. Such distortion may deteriorate the optical performance of the scanning optical system.

  Therefore, in view of the above circumstances, the present invention is a scanning optical unit in which laser light through a scanning optical system is emitted to the outside through an irradiation window provided in a cover portion, and is simpler and more efficient. An object of the present invention is to provide a scanning optical unit in which the inside of the housing can be hermetically sealed and the deterioration of optical performance due to a load or the like generated when the housing is attached to an image forming apparatus or the like can be reduced.

  In order to solve the above problem, a scanning optical unit according to claim 1 includes a housing having a reference surface on which the scanning optical system is disposed, and an opening for emitting a light beam through the scanning optical system to the outside. And a flexible cover portion attached to the housing from the side facing the reference surface, and facing the cover portion in a holding frame that holds the optical element located on the most exit side of the scanning optical system The end surface is positioned on substantially the same plane as the edge surface to which the cover portion is attached in the housing, and the cover portion has the edge surface and the holding frame in a state where the opening coincides with the space defined by the end surface of the holding frame. It is attached to the housing by adhering to the end face, and the inside of the housing is hermetically sealed by the cover portion, the holding frame, and the optical element.

  According to the scanning optical unit according to claim 1, the height of the edge surface and the holding frame end surface that abuts the cover portion is made uniform, and the cover portion is attached to the housing by bonding instead of screwing, so that the housing can be simplified. The inside can be sealed. Further, by adopting a flexible cover portion, it is possible to appropriately absorb the load applied from the outside of the unit when the housing body is distorted, and it is possible to effectively avoid the deterioration of the optical performance.

  According to the scanning optical unit of the second aspect, it is desirable that the cover portion has an adhesive margin in the vicinity of the opening that is folded back inside the holding frame at the end face of the holding frame and bonded to the inner wall of the holding frame. Thereby, the airtightness inside the housing is further enhanced.

  According to the scanning optical unit of the third aspect, it is desirable that the inner wall of the holding frame has a step at the boundary in the vicinity of the region where the bonding margin is bonded. This level | step difference is suitable in order to apply the jig | tool used when adhere | attaching a bonding margin on the inner wall of a recessed area.

  According to the scanning optical unit of claim 4, the edge surface and the end surface of the holding frame have positioning bosses in at least two places, and the cover portion has boss insertion holes corresponding to the bosses. It is desirable to have.

  According to the scanning optical unit of the fifth aspect, the cover portion may be coated with an adhesive on the surface facing the edge surface.

  According to the scanning optical unit of the sixth aspect, it is preferable that the cover portion has a light shielding property.

  Furthermore, according to the scanning optical unit of the seventh aspect, the optical element and the holding frame can be integrally formed. Thereby, while improving manufacturing efficiency, the sealing inside a housing can be improved further.

  As described above, according to the scanning optical unit of the present invention, even when the scanning optical unit emits laser light through the scanning optical system to the outside through the irradiation window provided in the cover portion, Thus, the inside of the housing can be hermetically sealed more simply and efficiently. In addition, according to the scanning optical unit of the present invention, by adopting a flexible cover portion, it is possible to reduce deterioration of optical performance due to a load or the like given from the outside when attached to an image forming apparatus or the like. Can do.

  FIG. 1 is a diagram schematically showing a configuration of a scanning optical unit 100 of the present embodiment. FIG. 2 is a diagram showing the scanning optical unit 100 with the cover sheet 50 removed. FIG. 3 is a cross-sectional view of the scanning optical unit 100 shown in FIG. As shown in each drawing, the scanning optical unit 100 includes a scanning optical system 10, a housing 30, and a cover sheet 50.

  As shown in FIGS. 2 and 3, the scanning optical system 10 includes a light source unit 11, a polygon mirror 12, a first scanning lens 13, a folding mirror 14, and a second scanning lens 16. The housing 30 includes a bottom surface 31, a side wall 32 provided along the outer periphery of the bottom surface 31, an edge surface 32 a of the side wall, and a plurality of positioning bosses 33 provided on the edge surface 32 a. The optical members 11 to 14 and 16 constituting the scanning optical system 10 are disposed on the bottom surface 31 of the housing 10. More specifically, the second scanning lens 16 is held by the lens holder 15 and is disposed on the housing bottom surface 31 via the lens holder. Thus, in the present embodiment, the bottom surface 31 is the reference surface.

  The configuration regarding the lens holder 15 and the second scanning lens 16 will be described. FIG. 4 is an enlarged view showing the lens holder 15 and the second scanning lens 16. The lens holder 15 is configured such that the front end surface 15a is located on substantially the same plane as the edge surface 32a of the housing. The front end surface 15a refers to a surface substantially parallel to a reference surface that can be seen when the scanning optical unit 100 with the cover sheet 50 not attached is viewed from above. A plurality of positioning bosses 15b are also provided on the distal end surface 15a. In this embodiment, the lens holder 15 and the second scanning lens 16 are integrally formed. As a result, it is possible to effectively prevent the entry of dust or the like into the housing 30 through the lens holder 15 and the second scanning lens 16, and to improve the manufacturing efficiency, and to maintain the positioning accuracy of the second scanning lens 16 high. To do

  Here, the scanning of the laser beam performed using the scanning optical unit 100 will be outlined. The laser light L emitted from the light source unit 11 is incident on the polygon mirror 12 via an optical system (not shown) (for example, a collimator lens) disposed between the light source unit 11 and the polygon mirror 12. The polygon mirror 12 has a plurality of deflection surfaces and rotates at high speed. Therefore, the laser light incident on the deflection surface of the polygon mirror 12 is deflected by the deflection surface. The deflected laser light L passes through the first scanning lens 13 and enters the folding mirror 14. The laser beam L whose optical path has been changed by the folding mirror 14 then passes through the second scanning lens 4. And the laser beam L is inject | emitted outside through the irradiation window 51 shown in FIG. The irradiation window 51 has a size corresponding to the inner dimension of the lens holder 15. A scanning surface (not shown) is disposed outside the scanning optical unit 100. The laser beam L scans the surface to be scanned in the main scanning direction.

  The cover sheet 50 is made of at least a flexible material. The cover sheet 50 of the present embodiment is made of a material that has not only flexibility but also light shielding properties. As a result, it is possible to effectively prevent a phenomenon in which external light enters the housing and becomes stray light. As the cover sheet 50, for example, an aluminum sheet having a thickness of about 2 to 3 mm is suitable. The cover sheet 50 is formed into a shape corresponding to the shape of the housing by a punching die. Therefore, there is a feature that molding is cheaper and easier than a conventional cover portion using sheet metal or the like.

  Moreover, the cover sheet 50 of the present embodiment is flexible and relatively thin as described above. For this reason, even when it is attached to the housing 30, even if it is excessive, that is, it protrudes from the side wall 32 of the housing 30, the protruding portion can be easily removed in a later step. Further, if the surplus is very small, it is difficult to dispose other members even if the cover sheet 50 is left alone due to the flexibility. Therefore, the shape of the cover sheet 50 does not necessarily correspond to the shape of the housing 30, and may be larger than the shape of the housing 30.

  In order to improve working efficiency, the cover sheet 50 of the present embodiment is bonded to other surfaces (here, the edge surface 32a and the tip surface 15a) without another medium. For example, the cover sheet 50 is bonded by heat sealing. However, the cover sheet which concerns on this invention is not limited to this, The cover sheet with which the adhesive sheet in which an adhesive surface appears by peeling a protective tape can also be used. In such a cover sheet, it is sufficient that the adhesive sheet is present at least in the contact area attached to the housing.

  The cover sheet 50 includes a slit 51a, boss insertion holes 52a and 52b, a notch 53, a bonding margin 54, and a flange 55. The slit 51a is a portion serving as a base of the irradiation window 51 formed for emitting laser light to the outside, and has a reduced size of the irradiation window 51. However, the cover sheet 50 in the present invention does not necessarily have such a configuration. For example, a configuration in which the bonding margin 54 is bent in advance and the irradiation window 51 is already formed instead of the slit 51a may be employed. The boss insertion hole 52 a has a position and shape corresponding to the positioning boss 33 provided in the housing 30. The boss insertion hole 52 b has a position and shape corresponding to the positioning boss 15 b provided in the lens holder 15. The bonding margin 54 is defined by a slit 51a and a notch 53 extending a predetermined amount from the end of the slit 51a. The collar portion 55 is formed in order to improve convenience when the cover sheet 50 attached to the housing 30 is peeled off from the housing 30.

  The cover sheet 50 is attached to the housing 30 in a state where each optical element constituting the scanning optical system 10 is disposed at a predetermined position on the bottom surface (reference surface) 31. Specifically, while adjusting the relative positions of the housing 30 and the cover sheet 50 so that the positioning bosses 33 and 15b respectively corresponding to the boss insertion holes 52a and 52b are fitted, the cover sheet 50 can be It abuts on the surface 32a and the tip surface 15a. Note that the slit 51 a of the cover sheet 50 is positioned substantially at the center of the space defined by the front end surface 15 a of the lens holder 15 in a state where the boss insertion holes 52 a and 52 b and the bosses 33 and 15 b are positioned. That is, in the state where the above positioning is performed, the space defined by the irradiation window 51 formed by the cover sheet 50 and the front end surface 15a of the lens holder 15 coincides. And the contact area | region of the cover sheet 50 and the housing 30 is heated using a known heating jig, and both are adhere | attached.

  As described above, in the present embodiment, the edge surface 52a and the front end surface 15a are positioned on substantially the same plane, in other words, positioned at substantially the same height, and the cover sheet is bonded rather than screwed. Is attached to the housing. Thereby, the housing 30 can be hermetically sealed by the housing 30, the cover sheet 50, the lens holder 15, and the second scanning lens 16. As described above, according to this embodiment, it is possible to attach the cover sheet to the housing while ensuring a high hermeticity while having a very simple configuration as compared with a complicated conventional attachment process. Moreover, since each member required with the conventional structure, such as a urethane foam and a screw, becomes unnecessary, cost reduction can also be aimed at.

  Further, by using the flexible cover sheet 50, even if there is a slight shift in the heights of the edge surface 52a and the tip end surface 15a, the interior of the housing can be reliably secured without being affected by the shift. Can be sealed. The positional relationship between the edge surface 52a and the front end surface 15a being described as being substantially on the same plane means that the cover sheet 50 does not necessarily have to be completely on the same plane. By adopting such a flexible cover sheet 50, when the scanning optical unit 100 is disposed in an image forming apparatus or the like, the load applied to the unit 100 is distorted by the housing 30 and the cover sheet 50. Therefore, it can absorb appropriately.

  In the scanning optical unit 100 of the present embodiment, the irradiation window 51 is formed as follows in order to ensure higher sealing performance.

  FIG. 5 is an enlarged sectional view of the vicinity of the lens holder 15 and the second scanning lens 16. In FIG. 5, the hatched area represents the cover sheet 50 (and the bonding margin 54). As described above, the slit 51 a provided in the cover sheet 50 is an opening serving as a base of the irradiation window 51, and the size thereof is smaller than the inner dimension of the irradiation window 51, that is, the lens holder 15. Therefore, at the stage where the contact area between the cover sheet 50 and the housing 30 is heated and bonded together, the irradiation window 51 as shown in FIG. 1 is not yet formed.

  When the bonding between the cover sheet 50 and the housing 30 is completed, as shown in FIG. 5, the bonding margin 54 is bent inside the lens holder by using the notch 53 and the edge of the front end surface 15a. Thereby, the irradiation window 51 is formed. The bonding margin 54 is bonded to the inner wall 15c inside the lens holder by the heating jig described above.

  Here, the inner wall 15c of the lens holder 15 has a step 15d in the vicinity of the boundary of the region where the bonding margin 54 abuts. More specifically, a step 15 d is formed such that the inner wall 15 c near the irradiation window 51 is more concave than the inner wall 15 d near the second scanning lens 16. As a result, the bonding margin 54 is bonded to the inner wall 15c very safely and reliably.

  In this way, the gap between the lens holder 15 and the cover sheet 50 is eliminated by bending the bonding margin 54 and bonding it to the inner wall 15 c to form the irradiation window 51. Therefore, the possibility that dust or the like enters the housing 30 from the irradiation window 51 is extremely reduced.

  The above is the description of the embodiment of the present invention. The present invention is not limited to the above-described embodiment. For example, even if the following modifications are made, the same effects as the above-described embodiment can be obtained.

  For example, in the above embodiment, the efficiency of the attaching operation of the cover sheet 50 is emphasized, and the surface of the cover sheet 50 that faces the housing 30 can be bonded to the other surface without any other medium. is doing. However, the scanning optical unit according to the present invention can also be configured such that the edge surface 32a and the tip surface 15a can be bonded to other surfaces without any other medium. Alternatively, an adhesive may be applied to the edge surface 32a and the tip surface 15a when the cover sheet 50 is attached to the housing 30.

It is a figure which shows schematically the structure of the scanning optical unit of embodiment of this invention. It is a figure which shows the scanning optical unit of the state which removed the cover sheet of embodiment. It is sectional drawing of the scanning optical unit of embodiment. It is an enlarged view of the lens holder of the embodiment and the vicinity of the second scanning lens. It is an expanded sectional view near the lens holder of an embodiment, and the 2nd scanning lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Scanning optical system 15 Lens holder 15a Front end surface 16 Second scanning lens 30 Housing 32a Edge surface 50 Cover sheet

Claims (7)

A housing having a reference surface on which the scanning optical system is disposed;
A flexible cover portion that has an opening for emitting a light beam through the scanning optical system to the outside, and is attached to the housing from a side facing the reference surface;
In the holding frame that holds the optical element located on the most exit side of the scanning optical system, an end surface that faces the cover portion is positioned substantially on the same plane as an edge surface to which the cover portion is attached in the housing. ,
The cover portion is attached to the housing by adhering to the edge surface and the end surface of the holding frame in a state where the opening coincides with a space defined by the end surface of the holding frame.
The scanning optical unit, wherein the inside of the housing is hermetically sealed by the cover portion, the holding frame, and the optical element. The scanning optical unit according to claim 1,
The scanning optical unit according to claim 1, wherein the cover has an adhesive margin in the vicinity of the opening that is folded back into the holding frame at the end face of the holding frame and bonded to the inner wall of the holding frame. The scanning optical unit according to claim 2,
The scanning optical unit according to claim 1, wherein the inner wall of the holding frame has a step in the vicinity of a boundary of an area where the bonding margin is bonded. The scanning optical unit according to any one of claims 1 to 3,
The edge surface and the end surface of the holding frame have positioning bosses in at least two places,
The scanning optical unit, wherein the cover part has a boss insertion hole corresponding to the boss. The scanning optical unit according to any one of claims 1 to 4,
The scanning optical unit according to claim 1, wherein an adhesive is applied to a surface of the cover portion that faces the edge surface. The scanning optical unit according to any one of claims 1 to 5,
The scanning optical unit, wherein the cover part has a light shielding property. The scanning optical unit according to any one of claims 1 to 6,
The scanning optical unit, wherein the optical element and the holding frame are integrally formed.

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