JP2005326691A - Method of manufacturing laser scanning optical apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method of manufacturing a laser scanning optical apparatus by which variations in the position (posture) of an optical element is prevented by suppressing the deformation of a base plate and a plate member due to laser beam welding, therefore, the laser scanning optical apparatus capable of highly accurately focusing a laser beam for scanning is obtained. <P>SOLUTION: When a horizontal face part 10a of the plate member 10 which holds a laser diode 1 and the base plate 15 are welded, a gap 11 is formed by arranging a spacer 12 between the horizontal face part 10a of the plate member and the base plate 15, and at least a point is welded with a laser or preferably with a YAG laser in the region in which the gap 11 is formed. For forming the gap 11, it is also possible to make the plate thickness of the horizontal face part 10a of the plate member 10 partially smaller, to arrange a projected part on the back face of the horizontal face part or to hold the plate member 10 with a holding fixture. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a laser scanning optical device, and more particularly, to a method for manufacturing a laser scanning optical device that emits a modulated laser beam to form an image on a photoreceptor.

  In general, an image forming apparatus such as an electrophotographic copying machine or printer incorporates a laser scanning optical device that emits a modulated laser beam in order to form an electrostatic latent image on a photosensitive member.

  In the laser scanning optical apparatus of this type, as shown in FIG. 8, with respect to the mounting of the laser diode, the sheet metal member 10 to which the laser diode 1 is mounted is laser-welded with its horizontal surface portion 10a in close contact with the base plate 15 ( The symbol a indicates the welding location and the welding direction).

  On the other hand, with respect to the mounting of the collimator lens, as described in Patent Document 1, the outer peripheral surface of the lens barrel holding the collimator lens and the plane of the base having the V-shaped groove holding the lens barrel are fixed by laser welding. Was.

  However, in the laser welding method shown in FIG. 8, the base plate 15 is deformed into a concave shape at the welding location a and the optical axis P changes to P ′, so that the imaging performance of the beam is not stable. Had.

That is, since the heat energy at the time of welding is directly transmitted to the base plate 15, as shown in FIG. 9, an inverted conical melting portion is generated in the base plate 15, and when the melting portion cools and hardens, The base plate 15 is deformed due to a difference in curing shrinkage. This deformation leads to the inclination of the vertical surface portion 10b of the sheet metal member 10. In FIG. 9, the melted portion of the metal is schematically shown as black.
JP 2001-111155 A

  Accordingly, an object of the present invention is to provide a laser capable of forming a scanning laser beam with high accuracy by suppressing deformation of the base plate and sheet metal member caused by laser welding to prevent a change in the position (posture) of the optical element. An object of the present invention is to provide a method for manufacturing a scanning optical device.

  In order to achieve the above object, a method for manufacturing a laser scanning optical device according to the present invention includes: a sheet metal member that holds an optical element and a base plate that fixes the sheet metal member; A gap is provided between and at least one spot is laser-welded in the area where the gap is provided.

  In the manufacturing method of the laser scanning optical device according to the present invention, since the gap is provided between the sheet metal member and the base plate, the thermal energy at the time of laser welding is not directly transmitted to the base plate. Alternatively, it is hardly transmitted, and the surface of the base plate is not melted into an inverted conical shape so that the surface of the base plate is deformed by curing shrinkage, so that the deformation of the sheet metal member is prevented. Thus, the position (posture) of the optical element held by the sheet metal member does not fluctuate, and the laser beam can be imaged with high accuracy.

  In the method for manufacturing a laser scanning optical device according to the present invention, as a method of forming a gap between the sheet metal member and the base plate, a spacer is interposed, the sheet thickness of the sheet metal member is partially reduced, and the protrusion on the sheet metal member It is possible to adopt a technique such as providing Further, the gap may be formed by holding the sheet metal member with a holding jig.

  For laser welding, YAG laser welding, carbon dioxide laser welding, or the like can be used. YAG laser welding is preferable in that it can be efficiently welded by condensing the laser with low power.

  The optical element held by the sheet metal member is, for example, a laser diode, a collimator lens or a cylindrical lens, or a compound lens of a collimator lens and a cylindrical lens.

  Embodiments of a method for manufacturing a laser scanning optical device according to the present invention will be described below with reference to the accompanying drawings.

(Refer to the first embodiment, FIGS. 1 and 2)
FIG. 1 shows a main part of a laser scanning optical device manufactured as a first embodiment, that is, a light source unit in which a sheet metal member 10 to which a laser diode 1 as a light source is attached is fixed on a base plate 15 by laser welding.

  In addition to the laser diode 1, the laser scanning optical device includes a collimator lens, a cylindrical lens, a deflector, a scanning lens having an imaging function and an fθ function, a scanning mirror, and the like. This is well known and will not be described.

  Both the sheet metal member 10 and the base plate 15 are made of a stainless material having a thickness of about 0.5 to 3 mm that can be laser-welded. The sheet metal member 10 includes a horizontal plane part 10a and a vertical plane part 10b orthogonal to each other, and the laser diode 1 is attached to the vertical plane part 10b so that its optical axis P is parallel to the horizontal plane part 10a.

  A small gap 11 is provided between the horizontal surface portion 10 a of the sheet metal member 10 and the base plate 15. In the first embodiment, the gap 11 is formed by interposing two rectangular spacers 12 between the horizontal surface portion 10 a and the base plate 15.

  Then, the sheet metal member 10 and the base plate 15 are laser-welded by irradiating a region having the gap 11 from the sheet metal member 10 side with a YAG laser. Symbol a indicates a welding location, and in the first embodiment, welding is performed at one location at the center of the region where the gap 11 is provided. In addition, as long as it exists in the area | region which provided the clearance gap 11, you may weld several places to a substantially equal position.

  As schematically shown in FIG. 2, the sheet metal member 10 is partially melted into a cylindrical shape by the thermal energy generated by the laser beam irradiation. The molten metal enters the gap 11 and the sheet metal member 10 and the base plate 15 are joined. Due to the presence of the gap 11, heat energy during welding is not directly transmitted to the base plate 15, or is hardly transmitted, and the surface of the base plate 15 melts into an inverted conical shape so as to be deformed by hardening shrinkage. There is no. Therefore, deformation of the sheet metal member 10 is prevented.

  In this way, the deformation of the base plate 15 is suppressed and the deformation of the sheet metal member 10 is also prevented, so that the laser diode 1 held by the sheet metal member 10 is not misaligned in the centering direction and the focus direction, and the laser. The laser beam emitted from the diode 1 can be imaged with high accuracy.

  By the way, YAG laser welding, carbon dioxide laser welding, or the like can be used for laser welding. YAG laser welding is preferable in that the laser can be condensed with low power and welding can be performed efficiently.

  A stainless steel material having a thickness of 1 mm was used as the sheet metal member 10 and the base plate 15, and the welding experiment was performed with the gap 11 set to 0.1 mm and the YAG welding energy set to 40 J. As a result, the base plate 15 and the sheet metal member 10 were transformed. It was confirmed that welding was carried out without causing any defects.

(Refer to the second embodiment, FIG. 3)
In the second embodiment, in order to provide a gap 11 between the sheet metal member 10 and the base plate 15, a spacer 13 having a rectangular opening 13a is interposed. And the laser welding of three places is performed to the area | region where the clearance gap 11 was provided by the opening part 13a, for example, as shown with the code | symbol a. Of course, laser welding may be performed at one place or two places.

  The operation and effects of the second embodiment are the same as those of the first embodiment, and other configurations than the configuration of providing the gap 11 are the same as those of the first embodiment. FIG. Are denoted by the same reference numerals, and the description thereof is omitted.

(Refer to the third embodiment, FIG. 4)
In the third embodiment, in order to provide a gap 11 between the sheet metal member 10 and the base plate 15, a disk-shaped spacer 14 having a circular opening 14a is interposed. And the laser welding of one place is performed to the area | region where the clearance gap 11 was provided by the opening part 14a, for example, as shown with the code | symbol a. Of course, laser welding may be performed at a plurality of locations.

  The operation and effect of the third embodiment is the same as that of the first embodiment, and the configuration other than the configuration of providing the gap 11 is the same as that of the first embodiment. FIG. Are denoted by the same reference numerals, and the description thereof is omitted.

(Refer to the fourth embodiment, FIG. 5)
In the fourth embodiment, in order to provide a gap 11 between the sheet metal member 10 and the base plate 15, a circular recess 10 c is formed on the back surface of the horizontal surface portion 10 a of the sheet metal member 10, and the thickness thereof is partially increased. Make it thinner. The recess 10c can be formed by punching or the like. And the laser welding of one place is performed to the area | region where the clearance gap 11 was provided by the recess 10c, for example, as shown with the code | symbol a. Of course, laser welding may be performed at a plurality of locations.

  The operational effects of the fourth embodiment are the same as those of the first embodiment, and the configuration other than the configuration of providing the gap 11 is the same as that of the first embodiment. FIG. Are denoted by the same reference numerals, and the description thereof is omitted.

(Refer to the fifth embodiment, FIG. 6)
In the fifth embodiment, since the gap 11 is provided between the sheet metal member 10 and the base plate 15, the horizontal surface portion 10a of the sheet metal member 10 is held by the holding jig 20 during laser welding. You may hold | maintain the vertical surface part 10b. Then, one or a plurality of laser weldings are performed on the region where the gap 11 is provided by the holding jig 20 as indicated by the symbol a. After welding, the holding of the sheet metal member 10 by the holding jig 20 is released.

  The functions and effects of the fifth embodiment are the same as those of the first embodiment, and the configuration other than the configuration in which the gap 11 is provided is the same as that of the first embodiment. Are denoted by the same reference numerals, and the description thereof is omitted.

(See the sixth embodiment, FIG. 7)
In the sixth embodiment, in order to provide the gap 11 between the sheet metal member 10 and the base plate 15, three projecting portions 10 d are formed on the back surface of the horizontal surface portion 10 a of the sheet metal member 10 concentrically and at equal intervals. And the laser welding of one place is performed to the area | region where the clearance gap 11 was provided by 10 d of protrusions, for example, as shown with the code | symbol a. Of course, laser welding may be performed at a plurality of locations.

  The operational effects of the sixth embodiment are the same as those of the first embodiment, and the configuration other than the configuration in which the gap 11 is provided is the same as that of the first embodiment. Are denoted by the same reference numerals, and the description thereof is omitted.

(Other examples)
The manufacturing method of the laser scanning optical device according to the present invention is not limited to the above-described embodiments, and can be variously modified within the scope of the gist thereof.

The principal part of the laser scanning optical apparatus manufactured by 1st Example of this invention is shown, (A) is sectional drawing, (B) is a top view. It is explanatory drawing which shows the welding state in this invention typically. The principal part of the laser scanning optical apparatus manufactured by 2nd Example of this invention is shown, (A) is sectional drawing, (B) is a top view. The principal part of the laser scanning optical apparatus manufactured by 3rd Example of this invention is shown, (A) is sectional drawing, (B) is a top view. The principal part of the laser scanning optical apparatus manufactured by the 4th example of the present invention is shown, (A) is a sectional view and (B) is a top view. It is sectional drawing which shows the principal part of the laser scanning optical apparatus manufactured by 5th Example of this invention. The principal part of the laser scanning optical apparatus manufactured by 6th Example of this invention is shown, (A) is sectional drawing, (B) is a top view. It is sectional drawing which shows the principal part of the conventional laser scanning optical apparatus. It is explanatory drawing which shows the conventional welded body typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser diode 10 ... Sheet metal member 10c ... Recess 10d ... Projection 11 ... Gap 12, 13, 14 ... Spacer 15 ... Base plate 20 ... Holding jig

Claims (7)

  When welding a sheet metal member for holding an optical element and a base plate for fixing the sheet metal member, a gap is provided between the sheet metal member and the base plate, and at least one spot is lasered in the region where the gap is provided. A method of manufacturing a laser scanning optical device, characterized by welding.   2. The method of manufacturing a laser scanning optical device according to claim 1, wherein the gap is formed by interposing a spacer between the sheet metal member and the base plate.   2. The method of manufacturing a laser scanning optical device according to claim 1, wherein the gap is formed by partially reducing a plate thickness of the sheet metal member.   The method of manufacturing a laser scanning optical device according to claim 1, wherein the gap is formed by providing a protrusion on the sheet metal member.   The method of manufacturing a laser scanning optical device according to claim 1, wherein the gap is formed by holding the sheet metal member with a holding jig.   6. The method of manufacturing a laser scanning optical device according to claim 1, wherein the laser welding is YAG laser welding.   The optical element held by the sheet metal member is at least one of a laser diode, a collimator lens, and a cylindrical lens. A method for manufacturing a laser scanning optical device according to claim 5.

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