JPH06331913A - Two-beam optical scanner - Google Patents

Abstract

PURPOSE:To separately adjust the positions of beams in a main scanning direction and in a subscanning direction with high accuracy by easy adjustment in a two-beam optical scanner which simultaneously scans a photoreceptor with two beams by using two semiconductor lasers. CONSTITUTION:This two-beam optical scanner is provided with two pairs of semiconductor lasers 1A and 1B and optical systems for shaping beams 2A and 2B, and two beams are synthesized by a beam synthesizing prism 3 and allowed to simultaneously scan two lines on the surface of the photoreceptor 10 so as to perform write by a deflector 6 and an image-formation optical system. Then, prisms 14 and 15 adjusting the positions of the respective beams in the write main scanning direction and the subscanning direction are installed between the optical systems 2A and 2B and the prism 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical writing device such as a laser printer, and more particularly to a two-beam optical scanning system that scans two beams simultaneously using two semiconductor lasers for two lines.

[0002]

2. Description of the Related Art In a conventional optical scanning optical system for performing laser beam recording, in order to achieve high-speed scanning, it is necessary to increase the rotation speed of a deflection mirror (polygon mirror or the like), which results in a high speed of air bearings. There is a problem in that high-precision manufacturing technology becomes indispensable and cost increases.

On the other hand, as disclosed in Japanese Patent Laid-Open No. 54-158251, there is also known a method of scanning a plurality of scanning lines simultaneously by using a plurality of light emitting portions of a semiconductor laser. However, in order to control the pitch of the scanning lines, it is necessary to precisely adjust the distance between the light emitting units and arrange them. Furthermore,
It is necessary to precisely control the angle of these light emitting portions in the arrangement direction, and therefore a highly accurate adjusting mechanism is indispensable.

The scanning optical system disclosed in Japanese Patent Laid-Open No. 58-68016 has a variable scanning line pitch in the sub-scanning direction. The writing device adjusts the scanning optical path in the sub-scanning direction using two adjusting screws.

Further, the one disclosed in Japanese Patent Laid-Open No. 62-86324 relates to a two-beam laser printer for adjusting the position of the collimator unit itself.

[0006]

In the two-beam optical scanning device, it is necessary to adjust the scanning line pitch in the sub-scanning direction and the distance from the dot index in the main scanning direction. The conventional adjustment method for both these scanning directions is
It required a highly accurate mechanism and complicated fine adjustment.

An object of the present invention is to realize high speed by a simple structure and method without requiring high design technology, high precision manufacturing technology or adjusting mechanism as in the above-mentioned conventional example, and It is an object of the present invention to provide a two-beam optical scanning device capable of adjusting the dot position from the index in the scanning direction and adjusting the scanning line dot pitch in the sub-scanning direction.

[0008]

A two-beam optical scanning device of the present invention that achieves the above object has two sets of semiconductor lasers and a beam shaping optical system, and combines the two beams by a beam combining prism. In a two-beam optical scanning device that performs writing by scanning two lines on the surface of the photoconductor at the same time by a deflector and an imaging optical system, a writing main scan is performed between the beam shaping optical system and the beam combining prism. It is characterized in that a prism for adjusting each beam position in the scanning direction and the sub-scanning direction is provided.

Further, the two-beam optical scanning device of the present invention is
Two sets of semiconductor lasers and a beam shaping optical system are provided, the two beams are combined by a beam combining prism, and two lines are simultaneously scanned on the photosensitive member surface by a deflector and an imaging optical system to perform writing. In the beam light scanning device,
At least one of the beam shaping optical system and the beam synthesizing prism is provided with a beam position adjusting prism, and the beam position adjusting prism is rotatable with respect to a rotating shaft for swingably holding the prism and the prism holding frame. It is characterized in that a fine adjustment means is provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A two-beam optical scanning device of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram showing an embodiment of a two-beam optical scanning device of the present invention.

In the figure, 1A and 1B are semiconductor lasers,
2A and 2B are collimator lenses (beam shaping optical system), 3 is a beam combining prism, 4 is an aperture, and 5
Is the first cylindrical lens, 6 is the polygon mirror, 7
Is an fθ lens, 8 is a second cylindrical lens, 9 is a mirror, and 10 is a photosensitive drum. In addition,
Reference numeral 11 is a timing detection mirror, 12 is a synchronization detector, and 13 is a drive motor for the polygon mirror 6. Further, 14 is a set of prisms for adjusting the main scanning direction, and 15 is a set of prisms for adjusting the pitch in the sub-scanning direction.

The beam emitted from the semiconductor laser 1A is
The collimator lens 2A collimates the light into parallel light, which then enters the beam combining prism 3. Similarly, the beam emitted from the semiconductor laser 1B arranged orthogonal to the semiconductor laser 1A is also collimated by the collimator lens 2B, and then enters the beam combining prism 3. In addition,
The beam emitted from the semiconductor laser 1B is arranged in the sub-scanning direction with a predetermined pitch offset from the beam emitted from the semiconductor laser 1A. Both beams pass through the aperture 4, pass through the first cylindrical lens 5 of the first imaging optical system, and enter the polygon mirror 6.
This reflected light is transmitted through a second imaging optical system including an fθ lens and a second cylindrical lens 8 and passes through a mirror 9 on the surface of the photoconductor drum 10 with a predetermined spot diameter and a predetermined pitch in the sub-scanning direction. Two lines are simultaneously scanned in the shifted state. The main scanning direction has already been finely adjusted by an adjusting mechanism (not shown).

In the synchronous detection for each line, the light beam before the start of scanning is guided to the second image forming optical system via the mirror 11 and is incident on the synchronous detector 12.

FIG. 2 shows the above-mentioned one prism set 14 (15).
It is a figure explaining the beam angle adjustment of. In the conventional method shown in FIG. 2A, since the collimator lens 2A (2B) is directly swung by the angle θ to obtain the deflection angle θ of the optical path,
It is difficult to accurately adjust the angle of the collimator lens 2A (2B). FIG. 2B shows an optical path deflecting method according to the present invention, in which a pair of prism sets 14 consisting of two prisms 14A and 14B is arranged near the collimator lens output, and the prism set 14 is rotated by an angle α. Thus, the optical path is swung by the desired deflection angle θ of the optical path.

FIG. 3 shows a pair of the prisms 14A, 14 described above.
7 is an optical path diagram for explaining the relationship between the exit deflection angle and the incidence angle of the prism set 14 made of B. FIG.

A beam incident at an angle .theta.1 with the normal line of the entrance surface (first surface) of one prism 14A exits from the exit surface (second surface) of the prism 14A to form a deflection angle X. To do. This deflection angle X is expressed by the following equation (1),
It is obtained by the simultaneous equations of (2), (3), and (4).

Θ2 = Sin ⁻¹ (n / N · Sin θ1) (1) θ3 = A1−θ2 (2) θ4 = Sin ⁻¹ (N / n · Sin θ3) (3) X = (θ1-θ2) + (θ4-θ3) (4) When the two prisms 14A and 14B are used as a set, the general formula of the deflection angle Y is as follows. ), (6), (7),
It is obtained by the simultaneous equations (8) and (9).

Θ5 = A1 + B−θ4 (5) θ6 = Sin ⁻¹ (n / N · Sin θ5) (6) θ7 = A2 + θ6 (7) θ8 = Sin ⁻¹ ( N / n · Sin θ7) ··· (8) Y = X + (θ5-θ6)-(θ8-θ7) ··· (9) where A1 and A2 are the apex angles B of the prisms 14A and 14B, respectively. The angle n formed by the first surfaces of both prisms 14A and 14B is the refractive index in air (= 1) N is the refractive index of the prism (1.51072 at FK7,780nm) where the apex angles A1 of prisms 14A and 14B are A2 is 4 °, and the angle B formed by the first surfaces of both prisms 14A and 14B is
Set 2.05 ° and set the rotation angle of prism set 14 to α of 10 °
When set to, the deflection angle θ of the optical path becomes 0.065 °. That is, the angle magnification is θ / α = 0.065 / 10 = 0.0065,
Therefore, the adjustment rotation angle θ of the collimator lens 2A (2B)
And the adjustment angle α of the prism set 14, θ / α is 1/1
Since it can be set to 00 or less, fine optical path adjustment in the main scanning direction can be easily performed by the prism set 14 having a two-sheet structure. Similarly, pitch adjustment can be easily performed for the optical path adjustment in the sub-scanning direction by rotating one prism set 15.

FIG. 4 is a plan view of a main part of a two-beam optical scanning device according to the present invention, FIG. 5 shows a main scanning and sub-scanning beam adjusting prism unit, and FIG. 5 (A) is a plan view. FIG. 5B is a left side view and FIG. 5C is a rear view. FIG. 6 is a partial perspective view of the sub-scanning prism unit.

A prism set 15 including the two prisms 15A and 15B is housed in a holder 16. The holder 16 is instructed by a support shaft 17 so as to be swingable and rotatable.
A wheel 18 is fixed to the shaft end of the support shaft 17,
The rotation of 19 causes a deceleration driven rotation. The achievement ratio of the wheel to the worm 19 is set to 1/10 to 1/20.
A knob 20 is fixed to the shaft end of the worm 19.

By rotating the knob 20 manually or electrically, the rotation angle β is reduced by the reduction ratio of the worm 19 and the wheel 18, and the support shaft 17 is rotated at the reduced rotation angle α. . As a result, the holder 16 integrated with the support shaft 17 and the built-in prism set 15 are
It swings in the vertical direction and is moved by a slight swing angle θ. Therefore, the rotation angle of the knob 20 is reduced to 1/20 to 1/30 by the first-stage worm wheel reduction means, and the second
By the swinging of the prism set 15 in steps, the speed is reduced to about 1/100, and a deceleration deflection angle θ of 1/2000 to 1/3000 is formed.
As a result, the knob 20 can be turned slowly and greatly, and a minute deflection angle adjustment can be performed with high accuracy.

Since the worm 19 and the wheel 18 are one-way drive transmission, even if a rotational force is applied from the holder 16 side, the worm wheel means does not prevent the worm 19 from rotating and the knob 20 adjusts the rotation. After the end, it is locked by reverse rotation prevention and will not move. Further, one end of the spring 21 is hooked to the holder 16 so that the play such as backlash of the worm wheel means and other transmission means can be removed.

As described above, the pitch of the beam emitted from the semiconductor laser 1B in the sub-scanning direction can be easily and precisely adjusted by the knob 20.

Further, in order to adjust the deflection angle in the main scanning direction, by providing the worm wheel means having the same configuration as described above, the deflection angle of the optical path can be easily and accurately performed manually or electrically. it can. Note that FIG.
In the main scanning beam adjustment prism unit shown in,
The parts having the same functions as the sub-scanning beam adjusting prism unit are given the same numbers.

[0026]

As described above, according to the two-beam optical scanning device of the present invention, a prism for adjusting each beam position in the main scanning direction and the sub-scanning direction is provided, and further, the prism for finely rotating the prism is provided. By providing the adjustment means,
The remarkable effect that the beam position of the main scanning direction beam and the beam of the sub scanning direction can be separately adjusted with high precision by easy adjustment is achieved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a two-beam optical scanning device according to the present invention.

FIG. 2 is a diagram for explaining beam angle adjustment of one prism set.

FIG. 3 is an optical path diagram of one prism set.

FIG. 4 is a plan view of a main part of a two-beam optical scanning device according to the present invention.

5A and 5B are a plan view, a left side view and a rear view of a prism unit for adjusting a main scanning beam and a sub scanning beam.

FIG. 6 is a partial perspective view of a sub-scanning prism unit.

[Explanation of symbols]

 1A, 1B Semiconductor laser 2A, 2B Collimator lens 3 Beam combining prism 5 First cylindrical lens 6 Polygon mirror (deflector) 7 fθ lens 8 Second cylindrical lens 10 Photosensitive drum 12 Synchronous detector 13 Drive motor 14 Main scanning direction adjustment Prism set 14A, 14B Prism 15 Prism set for sub-scanning direction pitch adjustment 15A, 15B Prism 16 Holder 17 Spindle 18 Wheel 19 Worm 20 Knob 21 Spring (elastic member) θ, X, Y Deflection angle of optical path

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Morita 2970 Ishikawacho, Hachioji City, Tokyo Konica Stock Company

Claims (5)

[Claims] 1. A semiconductor laser having two sets and a beam shaping optical system, wherein the two beams are combined by a beam combining prism, and two lines are simultaneously scanned on a surface of a photosensitive member by a deflector and an imaging optical system. In a two-beam optical scanning device for writing by writing, a prism for adjusting each beam position in the writing main scanning direction and the sub-scanning direction is provided between the beam shaping optical system and the beam combining prism. 2 beam optical scanning device. 2. A pair of semiconductor lasers and a beam shaping optical system, wherein the two beams are combined by a beam combining prism, and two lines are simultaneously scanned on the surface of the photoconductor by a deflector and an imaging optical system. In a two-beam optical scanning device for writing by writing, a beam position adjusting prism is arranged at least on one side between the beam shaping optical system and the beam combining prism, and the prism and the prism holding frame are swung. A two-beam optical scanning device comprising: a rotatable shaft that holds the rotatable shaft and a fine adjustment unit that enables the rotatable shaft. 3. The two-beam optical scanning device according to claim 2, wherein the fine adjustment means allows the rotary shaft to be rotated manually and / or electrically. 4. The fine adjustment means is a one-way deceleration transmission means including a worm and a wheel, a manual knob or a drive source is connected to the worm on the driving side, and a rotation shaft of the prism holding frame is attached to the wheel on the driven side. The two-beam optical scanning device according to claim 2, wherein the two-beam optical scanning device is connected. 5. The two-beam optical scanning device according to claim 4, wherein an elastic member is engaged with the prism holding frame and biased in a direction of rotating the wheel.