JPH1152262A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of scannable beam spots and to obtain an inexpensive high-performance optical scanner even in the case of using a collimator lens having the size of an image circle equivalent to the conventional one by arranging plural lines of elements where plural light beam generating means are gathered to be one line. SOLUTION: Six light beam outgoing from a light source unit 10 pass the collimator lens 11 and are changed into parallel beams. Thereafter, they pass a cylindrical lens 12 for correcting a plane tilt of a rotary polygon mirror 13 and are deflected to perform scanning by the mirror 13 rotated by a motor. The light beams pass an Fθ lens 15 and are converged to form an image on a photoreceptor 16. The six light beams scanning the photoreceptor 16 exist by three as two lines of beam spots and are arranged at an angle θ to a scanning line. The angle θ is adjusted so that the scanning pitch at such a time may be a specified value. A distance between two lines of beam spots is adjusted to the specified value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device used for a laser beam printer, a copying machine, etc., and more particularly to an optical scanning device for simultaneously scanning a plurality of beams.

[0002]

2. Description of the Related Art In order to realize high-speed printing and high dot density printing with a laser beam printer, it is necessary to increase the number of scans per unit time. To increase the number of repetitive scanning lines, it is possible to some extent by increasing the number of rotations of the rotating polygon mirror or the number of mirror surfaces, but there is a limit.
Therefore, it is well known that a multi-beam scanning method for scanning a large number of laser beams at once is effective.

For example, a single laser light source is separated into a plurality of laser beams, each of which is modulated by an output pattern signal and simultaneously scanned on a scanning surface via a single rotating polygon mirror and an Fθ lens. (Japanese Unexamined Patent Publication No. Sho 62-23911)
9) Alternatively, a plurality of individually modulatable semiconductor laser elements are arranged in an array, and each emitted light is made parallel by a single collimator lens, and scanned via a rotating polygon mirror and an Fθ lens. A method of simultaneously scanning the surface with a plurality of laser beams (Japanese Patent Publication No. 60-33019) has been proposed.

[0004]

In each of the above conventional examples, the beams are arranged in a line. Therefore, when the number of beams (density) increases, light is scattered at the peripheral portion of the lens of the optical system for introduction into the rotating polygon mirror, and a good beam spot is formed due to an increase in lens aberration. This makes it impossible to form an image on a predetermined place.

For example, an example of a collimator lens will be described. When two light sources 1 are arranged at a distance P as shown in FIG. 2, the size of the image circle 2 of the collimator lens is P + α.
There was no problem if it was more than about. α is a width for margin. However, when the number of light sources becomes three, the image cycle 2 of the collimator lens needs to be as large as 2P + α as shown in FIG. Further, as shown in FIG. 4, when the number of light sources becomes n, the image cycle 2 of the collimator lens becomes (n-
1) P + α is required. In this case, when n becomes large, a collimator lens having a large image cycle is required accordingly. To achieve this, a large image cycle, that is, an expensive collimator lens must be used, which raises a problem that the price of the entire apparatus increases.

[0006]

In order to solve the above-mentioned problems, the present invention provides a light beam generating means for a plurality of lights, a rotary polygon mirror for deflecting and scanning the light beam emitted from the light generating means, and an F beam.
In an optical scanning device composed of a θ lens, a plurality of optical beam generating means are gathered and arranged in one row.

In this multiple beam generating element, the distance between the elements in which one or more optical beam generating means are gathered and arranged in one row and / or the position of the elements in the column direction can be adjusted and fixed so that the scanning interval is increased. To adjust. The elements in which a plurality of light beam generating means are gathered and arranged in one row are arranged in parallel.

[0008]

FIG. 1 is an overall view of an embodiment of the present invention, and FIG. 5 shows details of a light source unit thereof. FIG. 5 shows an embodiment of a light source unit of a type in which three light sources are arranged and two light source arrays are arranged. This will be described first. A light source array 3 made up of three light sources 1 is held by a holder 4. Two of them are prepared, and the springs 5 are arranged so as to attract each other. These holders 4
A screw 6 is provided as a mechanism for adjusting the distance between. This is a light source unit. This light source unit is used in an optical scanning device as shown in FIG. In FIG. 1, six lights emitted from a light source unit 10 are collimated by a collimator lens 1.
1 and is made parallel light. Assuming that the distance between the light sources is P, a collimator lens having an image cycle of about 2P + α may be used as the collimator lens. After that, the cylindrical lens 12 for correcting the tilt of the rotating polygon mirror 13 is used.
Is deflected and scanned by the rotating polygon mirror 13 rotated by the motor 14. The light is Fθ lens 15
And is imaged on the photoconductor 16. FIG. 6 shows the state of six lights scanned on the photoconductor 15. There are three beam spots 20 and three beam spots 21 arranged at an angle θ with respect to the scanning line 25. At this time, θ is adjusted so that the scanning pitch B becomes a predetermined value. I have. Θ can be realized by adjusting the rotation of the entire light source unit 10. The distance L between the beam spot 20 and the beam spot 21 is adjusted so that the distance A becomes a predetermined value. This distance L can be realized by adjusting and fixing using the screw 6 shown in FIG.

Next, a second embodiment of the present invention will be described. FIG. 7 shows a second embodiment of the present invention. A light source array 3 formed by gathering three light sources 1 has a holder 4
Is fixed above. On the other hand, another light source array 3a is arranged so as to be adjustable and fixed in the direction in which the array is arranged. For example, in FIG. 7, the array 3a is pressed by a spring 5, and the position can be changed by a collimator lens with a screw 6 from the opposite side. By doing so, the array 3a can be finely adjusted and fixed in the direction in which the array is arranged. Even with this light source unit, optical scanning as shown in FIG. 1 is possible. FIG. 8 shows the state of the beam spot on the photosensitive member 16 in this case. There are three beam spots 22 and three beam spots 23, which are arranged at an angle θ with respect to the scanning line 25. At this time, θ is adjusted so that the scanning pitch B becomes a predetermined value.
Θ can be realized by adjusting the rotation of the entire light source unit 10. The distance M between the beam spot 22 and the beam spot 23 in the direction in which the beams are arranged is adjusted so that the distance C becomes a predetermined value. This M can be realized by adjusting the screw 6 shown in FIG.

Finally, a third embodiment of the present invention is shown in FIG. This example is an example in which two rows are used in the second embodiment of the present invention and three rows are used. One light source array 3 is fixed, and the remaining two light source arrays 3 are used as light sources. A light source unit using a three-row light source array is realized by making it possible to adjust the movement and fix it in the arrangement direction. FIG. 10 shows the state of the beam spot for scanning the photosensitive member 16 at this time.
Shown in FIG. 10 shows a state in which there are three groups formed by gathering three beam spots 24, each of which is inclined at an angle θ, and can scan uniformly like a scanning line 25.

In the above embodiment, three light source arrays and two or three rows are arranged. However, the number of light sources in the light source array and the number of light source arrays are both two or more. Then, it can be realized by making it similar to the embodiment of the present invention. Further, the combination of the number of light source arrays may not be the same, and for example, three and four may be combined.

[0012]

As described above, according to the present invention, in a multiple beam scanning optical system, a plurality of optical beam generating means are arranged in a single row and a plurality of elements are arranged in a plurality of rows. Since an image cycle such as a lens can be effectively used, the number of beam spots that can be scanned can be increased even if a collimator lens having the same size as the conventional image circle is used. It is possible to obtain a low-cost, high-performance optical scanning device.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing a relationship between a light source and a collimator lens in a conventional optical scanning device.

FIG. 3 is an explanatory diagram showing a relationship between another light source and a collimator lens in a conventional optical scanning device.

FIG. 4 is an explanatory diagram showing a relationship between still another light source and a collimator lens in a conventional optical scanning device.

FIG. 5 is a front view of a light source showing the first embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an arrangement of beam spots in the case of the first embodiment of the present invention.

FIG. 7 is a front view of a light source showing a second embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an arrangement of beam spots in the case of the second embodiment of the present invention.

FIG. 9 is a front view of a light source showing a third embodiment of the present invention.

FIG. 10 is an explanatory diagram showing an arrangement of beam spots in the case of the third embodiment of the present invention.

[Explanation of symbols]

1 is a light source such as a laser, 2 is an image cycle of a collimator lens, 3 is a light source array, 3 is a holder, 4 is a holder, 5
Is a spring, 6 is a screw, 10 is a light source unit, 11 is a collimator lens, 12 is a cylindrical lens, 13 is a rotating polygon mirror, 14 is a motor, 15 is an Fθ lens, 16 is a photoreceptor, 20, 21, and 22. , 23 and 24 are beam spots,
25 is a scanning line.

Claims (4)

[Claims] 1. An optical beam scanning device comprising: an optical beam generating means for a plurality of light beams; a rotary polygon mirror for deflecting and scanning an optical beam emitted from the generating means; and an Fθ lens. An optical scanning device, wherein a plurality of elements arranged in one row are arranged in a plurality of rows. 2. An optical scanning device according to claim 1, wherein said optical beam generating means is capable of adjusting and fixing the distance between a plurality of elements arranged in one line. 3. The optical scanning device according to claim 1, wherein the light beam generating means is capable of adjusting and fixing a position in a column direction of a plurality of elements arranged in one row. 4. The optical scanning device according to claim 1, wherein the light beam generating means is arranged such that a plurality of elements arranged in a row are arranged in parallel.