JPH0353213A - Optical scanner - Google Patents

Abstract

PURPOSE:To well-balancedly and effectively utilize the space by allowing an optical path of a luminous flux brought to guide by an optical deflector to pass through between the optical deflector and a condensing lens for scanning. CONSTITUTION:Cylindrical lenses 4a - 4d condense a luminous flux from laser oscillators 1a - 1d in the sub-scanning direction and forms a focal line in the vicinity of a deflecting/reflecting surface 7a of an optical deflector constituted of a rotary polygon mirror 7. In such a way, the laser oscillators 1a - 1d, condensing lenses 8a - 10a, 8b - 10b, 8c - 10c and 8d - 10d, surface 12a - 12d to be scanned, etc., are provided so as to become a surface symmetrical constitution with regard to a plane containing a rotation axis 0 (perpendiculer to the place of the figure) of the rotary polygon mirror 7. In such a way, the space can be utilized well-balancedly and effectively.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical scanning device that scans a beam from a light source onto an irradiated object, and particularly relates to a color laser beam printer having an electrophotographic process or a multicolor laser beam printer. The present invention relates to an optical scanning device for scanning multiple beams of light, which is suitably used in image forming apparatuses such as beam printers.

[Prior Art] Conventionally, as an optical scanning device such as a color laser printer, which uses i number of laser beams to optically scan the surface of an image carrier and write an image, an optical deflector consisting of a rotating polygon mirror has been used. In some cases, the optical system is arranged symmetrically with respect to the plane containing the rotation axis of the rotating polygon mirror, and two laser beams are guided to each deflection surface on either side of this plane. A guide format has been proposed. In these types, the light beam is incident on the optical deflection surface of the rotating polygon mirror from one side with respect to the optical axis of the optical scanning lens, and the optical system from the laser driver and laser oscillator is concentrated on this one side. ing.

[Problems to be Solved by the Invention] However, if a configuration such as the above conventional example is adopted, many elements and optical members are concentrated in a narrow space, resulting in a spatially complex arrangement. There wasn't. In particular, with regard to laser drivers, since the circuit board mounting space is limited, there may be problems with the responsiveness of circuits that are required to be driven at high speed.

Therefore, in view of the above-mentioned problems, it is an object of the present invention to provide an optical scanning device for scanning multiple beams of light, which enables a spatially spacious arrangement. [Means for Solving the Problems 1] In the present invention to achieve the above object, a plurality of light beams emitted from a light source such as a laser oscillator are transmitted through a single optical deflector such as a rotating polygon mirror or a galvanometer mirror. In an optical scanning device that scans the beam by deflecting the beam and guiding the beam onto the corresponding scanning surface through a scanning condenser lens. The optical path of at least one beam guided to the optical deflector is configured to pass between the optical deflector and the scanning condensing lens. [Operation J] In the present invention having the above configuration, light source devices such as laser drivers and laser oscillators and optical systems are arranged on both sides of the optical axis of the scanning condensing lens, so the space can be effectively balanced. It is often used, and as a result, enough space is available for installation, leaving more space for mounting the laser driver electrical board. Therefore, there is no need for a complicated mounting arrangement, and the structure of the optical scanning device itself can be simplified. [Embodiment] FIG. 1 is an optical path diagram showing a configuration in a scanning plane and a configuration in a sub-scanning direction cross section perpendicular to the scanning plane of a first embodiment of the present invention.

In the figure, the configuration of this embodiment is to optically scan each surface to be scanned using four laser beams, each having different optical information, and la. lb%lc, ld are semiconductor laser oscillators; 2a, 2b, 2c, and 2d are collimator lenses that convert the luminous flux emitted from the semiconductor laser oscillator 1axld into a parallel luminous flux; 3a, 3b. 3
4a, 4b, 4C, 4d are cylindrical lenses having refracting power in the sub-scanning direction, and these cylindrical lenses 4a to 4d are used for the laser oscillator 1.
The light beam from a=ld is focused in the sub-scanning direction and rotated by a rotating polygon fi.
A focal line is connected near the deflection reflecting surface 7a of the optical deflector consisting of 7. Further, 5a and 5b are laser oscillators lb and ld, respectively.
The light beams from the . They are mirrors that guide the scanning plane to the same position at a predetermined pitch in the sub-scanning direction (see section CC in FIG. 9a. loa. 8b
．． 9b. lOb;8c. 9c, 10c. 8d. 9d%
Regarding the optical axis of LOD, on both sides, cylindrical lens 4a% 4b; 4c, 4d and collimator lens 2a
．． 2b: 2c. 2d and laser oscillator la, lb
;1c. 1d etc. can be placed. In addition, as can be seen from FIG. 1, the side on which the laser beam is incident on the rotating polygon mirror 7 (the lower half of FIG. 1) and the opposite side (the first
Laser beam (laser oscillator 1) from the upper half of the figure)
b, 1d) is transmitted through the rotating polygon mirror 7 and the scanning condensing lenses 8a to 10a. 8b-10b; 8c-10
c. The light passes between 8d and 10d and is incident on the reflecting surface 7a of the rotating polygon mirror 7. In the above configuration, the spherical lenses 8a to 8d. 9a-9d
The scanning condensing lens composed of the anamorphic lenses loa to 10d has f/θ characteristics in the scanning direction, and in the sub-scanning direction, the conjugate point is set between the deflecting reflection surface 7a and the scanned surface 12a% 12b. 12c and 12d are set as an anamorphic lens system, so that even if the reflecting surface 7a of the rotating polygon mirror 7 falls, the beam can be scanned at the same position on the scanned surface 12a=12d. (
(face tilt correction), the beam deflected and scanned by the rotating polygon mirror 7 that rotates at a constant speed, and the scanning dots move linearly at a constant speed on the scanned surfaces 12a to 12d? It is converted to perform the following. In addition, 6a, 6b. lLa,'1■lb is a dustproof cover glass. As described above, in the first embodiment, the rotation axis O of the rotating polygon mirror 7 is
The laser oscillator 1a=1d. Condensing lenses 8a to 10
a, 8b~l Ob, 8c~1 0c. 8d-1 0d
% scanning surfaces 12a to 12d, etc. are arranged, and the space is effectively utilized in a well-balanced manner. FIG. 2 shows a schematic perspective configuration of a second embodiment of the present invention. In the second embodiment, one side of the rotating polygon mirror 7 includes a surface 7a that deflects and reflects four laser beams, and a laser oscillator 1e to 1.
h, collimator lenses 2e to 2h, and light flux apertures 30 to 3
h, cylindrical lenses 4e to 4h, scanning condensing lenses 8e to 8h, 9e to 9h. lOe-10h are arranged. And scanning condensing lenses 8e to 8h.
9 e to 9 h. Two laser oscillations on each side of the optical axis of lOe-10h,
11'; lg. 1h and collimator lenses 2e, 2f:
2g, 2h and light flux apertures 3e, 3f'. 3g, 3h and cylindrical force lenses 4e, 4f. 4g. 4h is arranged,
Rotating polygon mirror 7 and scanning condensing lenses 8e to 8h, 9e to
9h. Between loe and loh, the racer oscillator 1e. 1
Two laser beams from f (the beam from laser oscillator If is reflected by mirror 5C) are guided, reflected by mirrors 5e and 5f, and incident on deflection reflection surface 7a. Two laser beams from laser oscillators 1g and 1h (
The beam from the laser oscillator ih is reflected by the mirror 5d) and enters the deflection reflection surface 7a as it is.

The second embodiment has an advantageous configuration in that the apparatus itself can be miniaturized when the optical path length of the optical scanning beam is long. In addition, the four light beams are used to scan four images of yellow, magenta, cyan, black, or red, green, blue, and black for an image forming apparatus that generates full-color images by multiple transfer. Used. Other functions are the same as in the first embodiment. FIG. 3 shows a schematic perspective configuration of a third embodiment of the present invention. In the third embodiment, compared to the second embodiment, two light beams arranged on both sides of the optical axes of the scanning condensing lenses 81 to 8ε, 91 to 9I2, and Lot to 10{ are one each. It is oscillated by monolithic two-beam laser oscillators 11 and 1j, and collimator lenses 21 and 2j common to the two beams and beam diaphragms 31 and 3j (the diaphragms 31 and 3j are placed on the focal planes of collimator lenses 2i and 2j to form a telecentric system). ) and passes through the cylindrical lenses 41 and 4j and enters the common deflection reflection surface 7a. The two beams from one monolithic two-beam four-laser oscillator 1i are reflected by a common mirror 5g between the rotating polygon mirror 7 and scanning condensing lenses 81 to 8e, etc., and are incident on the reflecting surface 7a. There is. Other optical principles are essentially the same as in the first and second embodiments. In the third embodiment, the configuration is further simplified, and the laser oscillator 1i. This creates more space in the vicinity of 1j. [Effect of the invention 1] As explained above, in the optical scanning device of the present invention that scans a plurality of light beams, the light sources and optical systems can be arranged in a well-balanced manner on both sides of the optical axis of the scanning condensing lens. This allows for more space to be used around light sources such as laser oscillators. Therefore, it is possible to integrate and arrange components such as laser drivers that require high response speed, and it is also possible to make the optical scanning device itself a simple and compact structure.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of the first practical example of the present invention, FIG. 2 is a schematic perspective configuration diagram of the second embodiment, and FIG. 3 is a schematic perspective configuration diagram of the third embodiment. ...Laser oscillator, 2a-2j...Collimator lens, 3a-
3j...Flux aperture %4a~4j...Cylindrical lens, 5a~5g...Mirror, 7...
...Rotating polygon mirror, 8a to 8Q, 9a to 9g, loa
~lOn... Scanning condensing lens, 12a-12d
...Scanned surface

Claims (1)

[Claims] 1. A plurality of light beams emitted from a plurality of light sources are deflected through a single optical deflector, and guided onto corresponding scanned surfaces through a scanning condenser lens. What is claimed is: 1. An optical scanning device that performs optical scanning, wherein the optical path of at least one beam guided to an optical deflector passes between the optical deflector and a scanning condensing lens. 2. The optical scanning device according to claim 1, wherein the at least one light beam passes between the optical deflector and a scanning condensing lens, is reflected by a mirror, and is guided to the optical deflector. 3. The optical deflector is composed of a rotating polygon mirror, and the light source, the condenser lens, and the surface to be scanned are arranged so as to have a planar symmetry with respect to a plane containing the rotation axis of the polygon mirror. The optical scanning device described. 4. The light deflector is configured so that four light beams are guided to one deflection surface, and each of the four light beams is a yellow light beam for an image forming apparatus that generates a full-color image by multiple transfer;
The optical scanning device according to claim 1, which is used as a light beam for scanning four images of magenta, cyan, and black, or red, green, blue, and black. 5. The light source is composed of two monolithic two-beam laser diodes that each emit two light beams, and four light beams are guided to one deflection plane of the optical deflector, and from one of the two laser diodes. The optical path of the two light beams is configured to pass between the optical deflector and the scanning condensing lens, and the four light beams are yellow light beams for use in an image forming apparatus that generates a full-color image by multiple transfer. , magenta, cyan, black or red, green,
The optical scanning device according to claim 1, which is used as a light beam for scanning four images of blue and black. 6. Two light beams are guided to one deflection surface of the rotating polygon mirror on both sides of the plane including the rotation axis, and one optical path of the two light beams connects the optical deflector and the scanning condenser. The four light beams are configured to pass between a light lens, and the four light beams are yellow, magenta, cyan, black, or red, green, blue, and black for an image forming apparatus that generates a full-color image by multiple transfer. 4. The optical scanning device according to claim 3, wherein the optical scanning device is used as a light beam for scanning four images.