JPH0573619U - Optical scanning device - Google Patents

Abstract

(57) [Summary] [Object] To provide an optical scanning device that can eliminate unnecessary attachment and adjustment work, promote automation of assembly work, reduce the number of parts, and reduce device cost. An optical deflector 12 that scans and deflects a light beam B11 output from a light source unit 11, and an fθ first and second lens 13 that focuses the scan-deflected light beam B12 on a photosensitive surface 16a of a photosensitive drum 16. , 14 and a photodetector 17 for detecting the scanning start timing, which is provided at a position P11 on the optical deflector 12 side of the equivalent surface of the photosensitive surface 16a, in the fθ second lens 14, A light beam B13 having a focal length shorter than that of the fθ second lens 14 and closer to the scanning start side than the light beam B12 is focused on the light receiving surface 17a of the photodetector 17 at the side portion on the scanning start side in the main scanning direction N. The focusing lens 15 is integrally provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical scanning device used in a laser beam printer or the like.

[0002]

[Prior Art]

 Generally, in an optical scanning device used for a laser beam printer or the like, for example, as shown in FIG. 2, a light beam B1 from a light source unit 1 including a laser diode is scanned and deflected in a main scanning direction M by an optical deflector 2. The scanning-deflected light beam B2 is focused on the photosensitive surface 5a of the photosensitive drum 5 by the fθ first and second lenses 3 and 4 for scanning.

By the way, in order to obtain the timing for starting the writing of information on the photosensitive surface 5a by the scanning-deflected light beam B2, as shown in FIG. It is preferable to dispose a photodetector for timing detection at a position P1 on the equivalent surface of the surface 5a. However, if a photodetector for timing detection is arranged at the position P1, the size of the housing (not shown) of the optical scanning device that accommodates the photodetector becomes large. As shown in FIG. 2, a light beam B3, which is scanned and deflected by the optical deflector 2 toward the scanning start side in the main scanning direction M with respect to the photosensitive drum 5, is reflected by the reflection mirror 6, and the reflected light beam B4 is reflected. The optical path of is corrected by the correction lens 7 and the light beam B4 is focused on the photodetector 8 arranged at the position P2.

[0004]

[Problems to be solved by the device]

 However, as described above, in the related art, the reflection mirror 6 for reflecting the scanning-deflected light beam B2 toward the photodetector 8 and the correction of the optical path of the light beam B2 to focus the light beam on the photodetector 8 are performed. Since the compensating lens 7 and its mounting parts are required, the number of parts increases and the cost of the apparatus increases, and in addition to adjusting the arrangement position of the photodetector 8, the reflecting mirror 6 and the compensating lens. Since it is necessary to adjust the mounting position and angle of No. 7, there is a problem that the adjustment process increases and it hinders the automation of the assembly of the device. The present invention has been made in view of the above problems, and an optical scanning device capable of eliminating unnecessary mounting and adjusting work to promote automation of assembly work and reducing the number of parts to reduce the device cost. The purpose is to provide.

[0005]

[Means for Solving the Problems]

 To achieve the above object, the present invention provides an optical deflector that scans and deflects a light beam output from a light source unit, a scanning lens that focuses the scan-deflected light beam onto a scan target, and a scan lens that scans the scan target. In an optical scanning device including a photodetector for detecting a scan start timing, which is arranged at a deviated position, focusing for focusing the scanning-deflected light beam on the scanning lens toward the photodetector. The feature is that the lens is integrated.

[0006]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a schematic configuration of an optical scanning device according to an embodiment of the present invention. In this embodiment, the case of using it in a laser beam printer will be explained. In FIG. 1, 11 is a light source unit including a laser diode, and 12 is an optical deflector for scanning and deflecting a light beam B11 emitted from the light source unit 11 in the main scanning direction N. Reference numerals 13 and 14 are fθ first and second lenses as scanning lenses for focusing the light beam B12 scanned and deflected by the optical deflector 12 on the photosensitive surface 16a of the photosensitive drum 16 to be scanned. The light beam B12 focused on the light-sensitive surface 16a by the fθ first and second lenses 13 and 14 is moved from the write start position S1 on the light-sensitive surface 16a along with the movement in the main scanning direction N to end the writing. Scan up to the position S2.

Reference numeral 17 in FIG. 1 is for detecting the scanning start timing of the light beam B12 for scanning the photosensitive surface 16a, that is, the position S1 for starting the writing of information on the photosensitive surface 16a by the light beam B12. It is a photodetector, and is disposed at a position P11 on the optical deflector 12 side with respect to the equivalent surface of the photosensitive surface 16a, which is out of the printing range in the main scanning direction N. Then, in the optical scanning device of the present embodiment, based on the timing at which the photodetector 17 detects the light beam B13 on the scanning start side of the light beam B12 reaching the writing start position S1 on the photosensitive surface 16a, Writing of information on the photosensitive surface 16a by the beam B12 is started. In this embodiment, a two-divided sensor is used as the photodetector 17 in order to improve the detection accuracy of the light beam L13.

At the side of the fθ second lens 14 on the scanning start side in the main scanning direction N, a focusing lens 15 that focuses the light beam B13 onto the light receiving surface 17a of the photodetector 17 is provided as fθ. It is provided integrally with the second lens 14. The focusing lens 15 emits a convex light having a smaller radius of curvature than the convex light emitting surface 14a of the fθ second lens 14 in both the main scanning direction N and the sub-scanning direction orthogonal to the main scanning direction N. It has a surface 15a, so that the focal length of the focusing lens 15 is shorter than the focal length of the fθ second lens 14. In this embodiment, the fθ second lens 14 and the focusing lens 15 are integrally formed by molding using plastic as a material.

In the optical scanning device of the present embodiment configured as described above, the focusing lens 15 for focusing the light beam B 13 on the light receiving surface 17 a of the photodetector 17 is provided integrally with the fθ second lens 14. Therefore, by adjusting the mounting position of the fθ second lens 14, the position of the focusing lens 15 is also adjusted at the same time, and it is not necessary to separately adjust the mounting position of the focusing lens 15, thus facilitating automation of the assembly work. To be able to. Further, by providing the focusing lens 15 integrally with the fθ second lens 14, it is not necessary to provide a separate component for focusing the light beam B13 on the light receiving surface 17a of the photodetector 17 or a mounting component thereof. , The number of parts can be reduced and the device cost can be reduced.

Although the focal length of the focusing lens 15 may be longer than the focal length of the fθ second lens 14, the focal length of the focusing lens 15 is set to the focal length of the fθ second lens 14 as in this embodiment. If the length is shorter than the above, it is not necessary to increase the housing (not shown) of the device according to the position where the photodetector 17 is arranged, and it is not necessary to reflect the light beam B13 by the reflection mirror as in the conventional case. By eliminating the need for mounting parts and their mounting parts, it is possible to save the trouble of adjusting the mounting position, promote automation of assembly work, reduce the number of parts, and lower the device cost.

In this embodiment, the fθ second lens 14 and the focusing lens 15 are integrally formed by molding using plastic as a material. However, for example, molding using glass as a material or It may be integrally formed by cutting. Further, in the present embodiment, the fθ second lens 14 and the focusing lens 15 have convex curved surfaces on the light emitting surfaces 14a and 15a thereof. However, for example, the fθ second lens 14 and the focusing lens 15 are incident on the light. A concave curved surface may be formed on the surface, or the fθ second lens 14 and the focusing lens 15 may be formed of different materials having different refractive indexes, and the both may be integrally joined. ..

Further, in this embodiment, the focusing lens 15 is provided integrally with the fθ second lens 14, but the focusing lens 15 may be provided integrally with the fθ first lens 13, and the fθ first and A focusing lens may be provided integrally with each of the second lenses 13 and 14. Further, in the present embodiment, the case where the optical scanning device of the present invention is used for the laser beam printer has been described, but the optical scanning device of the present invention is applicable to other image scanners, for example. Of course.

[0013]

[Effect of the device]

 As described above, according to the present invention, an optical deflector that scan-deflects a light beam output from a light source unit, a scanning lens that focuses the scan-deflected light beam on a scan target, and the scan target An optical scanning device comprising a photodetector for detecting a scanning start timing, which is arranged at a position deviated from the above, and a focusing lens for focusing the scanning-deflected light beam on the scanning lens toward the photodetector. The lens is integrated. Therefore, a separate component for focusing the light beam toward the photodetector and its mounting component can be dispensed with, thus facilitating assembly work by eliminating unnecessary attachment adjustment work. In addition, it is possible to reduce the number of parts and reduce the device cost.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of an optical scanning device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a schematic configuration of a conventional optical scanning device.

[Explanation of symbols]

 Reference Signs List 11 light source section 12 optical deflector 14 fθ second lens (scanning lens) 15 focusing lens 16 photosensitive drum (scanning target) 17 photodetector B11, B12, B13 light beam P11 photodetector installation position

Claims (1)

[Scope of utility model registration request] 1. An optical deflector for scanning and deflecting a light beam output from a light source unit, a scanning lens for focusing the scanned and deflected light beam onto a scan target, and a lens disposed outside the scan target. In the optical scanning device including a photodetector for detecting the scanning start timing, the focusing lens for focusing the scanning-deflected light beam toward the photodetector is integrally provided on the scanning lens. An optical scanning device characterized by the above.