JPH11295626A - Multi-beam light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust the relative positions of the light beams of a sub-scanning direction without using optical parts such as a prism. SOLUTION: This multi-beam light source is constituted of plural light emission parts 21-24 for integrally holding a semiconductor laser and a collimator lens making the semiconductor laser beams into parallel luminous flux, arranged in a main scanning direction and in the sub-scanning direction and attachably and detachably held by an identical holding member 10, a beam synthesis means (prism) 26 emitting the parallel luminous flux emitted from the plural light emission parts arranged in the sub-scanning direction by making them near to one another and a means 6 driving the light emission parts to be rotated with rotary shafts 11-14 eccentric away from an optical axis as a center. By rotating the light emission parts on the rotary shafts by the driving means 6, the arrangement positions of the light emission part 21-24 with respect to the synthesis means 26 are changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multi-beam light source device for a semiconductor laser. INDUSTRIAL APPLICABILITY The present invention can be applied to a light source device of an optical scanning device such as a digital copying machine and a laser printer, thereby helping to increase a copying speed and a printing speed, and in particular, it is possible to reduce the size of the device.

[0002]

2. Description of the Related Art For adjusting the position of a light beam in the sub-scanning direction, for example, JP-A-6-331913 has two sets of semiconductor lasers and a beam shaping optical system.
The two beams are combined by a beam combining prism,
When writing is performed by simultaneously scanning two lines on the photoconductor surface via an imaging optical system or the like, a prism is provided between the beam shaping optical system and the beam combining prism, and the adjustment is performed by moving the prism. A "two-beam optical scanning device" (referred to as the former) is disclosed. As a device for changing the scanning line pitch of the multi-beam, for example, Japanese Patent Application Laid-Open No. 9-193458 discloses a light source device containing two semiconductor lasers and combining light beams by combining means around the optical axis. A “multi-beam scanning device” (referred to as the latter) that changes the sub-scanning pitch between beams by rotating is disclosed.

[0003]

The former adopts a configuration in which a prism is provided between a beam shaping optical system and a beam combining prism to move the beam in order to adjust the position of the light beam in the sub-scanning direction. Therefore, there is a problem that the size of the apparatus is large and the cost is high for performing the adjustment. In the configuration adopted in the latter, the sub-scanning pitch of two light beams can be changed, but there is a problem that the sub-scanning pitch of three or more light beams cannot be changed.

Accordingly, an object of the present invention is to provide a multi-beam (two or more beams can be used) without using an optical component such as a prism to change the sub-scanning position of the beam. Another object of the present invention is to provide a multi-beam light source device that enables high-speed writing at low cost, simplifies the operation of adjusting the relative position of the light beam in the sub-scanning direction, and improves the operation efficiency.

Further, the objects of the invention according to each claim are as follows. A first object of the present invention is to make it possible to independently change the positions of a plurality of light beams in the sub-scanning direction, to shorten the adjustment work time, and to make it possible to shorten the semiconductor laser in the event of a failure (e.g. In this case, the unit in which the semiconductor laser and the collimating lens are integrated is made independent of the light source device, so that only the broken unit can be replaced, thereby reducing the repair cost. An object of claim 2: an optical axis alignment operation after replacement of the light source device by making the light source device detachably holdable in the housing of the optical scanning device so that the arrangement of the beams in the light source device can be adjusted. Is unnecessary.

An object of the present invention is to make it possible to independently change the sub-scanning positions of a plurality of LD lights and to efficiently perform an adjustment operation. An object of claims 4 and 5 is to enable the arrangement of a plurality of LDs to be easily adjusted and set reliably.

[0007] The object of claim 6 is to change the emission angle in the main scanning direction for each of the plurality of LD lights arranged in the sub-scanning direction, so that a plurality of LD lights are arranged at intervals in the main scanning direction on the surface to be scanned. It is another object of the present invention to obtain a high-quality image by enabling synchronization detection for determining a write start timing for each LD light to be independently detected. The object of claim 7 is to fix the light emitting portion of the reference light beam to the holding member, thereby reducing the fluctuation of the position of the reference beam due to environmental fluctuations, etc., and increasing the accuracy of other beam positions based on the reference beam. As a result, a high-quality image can be obtained.

[0008]

According to a first aspect of the present invention, there are provided a plurality of light emitting units integrally holding a semiconductor laser and a collimating lens for converting a semiconductor laser beam into a parallel light beam, and the plurality of light emitting units in a sub-scanning direction. A multi-beam light source device comprising: a beam combining unit that emits a parallel light beam from a light source in a close state; and a unit that changes an arrangement position of the light emitting unit with respect to the beam combining unit.

According to a second aspect of the present invention, there is provided the multi-beam light source device according to the first aspect, wherein the plurality of light-emitting portions are detachably held by the same holding member.

According to a third aspect of the present invention, in the multi-beam light source device according to the first or second aspect, the means for changing the arrangement of the light emitting unit is arranged such that the light emitting unit is arranged around a rotation axis eccentric to the optical axis. This is a multi-beam light source device that is a means for rotationally driving.

According to a fourth aspect of the present invention, in the multi-beam light source device according to any one of the first to third aspects, the main scanning direction of the semiconductor laser beams of the plurality of light emitting units arranged in the sub-scanning direction. Is a multi-beam light source device whose emission positions are matched.

According to a fifth aspect of the present invention, in the multi-beam light source device according to any one of the first to third aspects, the emission direction of the semiconductor laser light of each of the plurality of light emitting units arranged in the sub-scanning direction is mainly used. This is a multi-beam light source device having a predetermined angle in the scanning direction.

According to a sixth aspect of the present invention, in the multi-beam light source device according to the fifth aspect, the predetermined angle can be changed for each of the plurality of light emitting units arranged in the sub-scanning direction. Device.

According to a seventh aspect of the present invention, in the multi-beam light source device according to any one of the first to sixth aspects, one of the plurality of light emitting units is used as a reference beam, and its position is fixed and fixed. This is a multi-beam light source device that corrects another beam relatively to the reference beam.

[0015]

FIG. 1 is an exploded perspective view of a light source unit 40, and FIG. The light source unit of this embodiment combines and emits four light beams of four semiconductor lasers. The light source is roughly divided
A prism holder 10 for accommodating four light emitting units 21 to 24, a prism which is a beam synthesizing means for synthesizing a light beam while attaching the light emitting units 21 to 24, and light emitting units 21 to 24
And an urging spring (torsion coil spring) 4.

In the prism holder 10, four stepped rotating shafts 11 to 14 are installed in directions parallel to each other.
Each of the stepped rotating shafts 11 to 14 has a light emitting unit 21.
To 24 are attached. At the center of the prism holder 10 is a recess 15 in which a prism 26 is housed. Further, two projections 16 and 17 for locking the end of the torsion coil spring 4 are provided.

The light emitting units 21 to 24 have the following configuration. The light emitting unit 21 will be described as a representative example. A semiconductor laser (hereinafter simply referred to as an LD) 1 has an LD base 2
In the fitting hole 2a. Collimating lens 3
Are bonded and fixed to the LD base 2 with the optical axis of the LD 1 substantially aligned with the protrusion 2b of the LD base. This gives L
The laser light emitted from D1 is converted into a parallel light beam.

The LD base 2 is provided with a hole 2c in a direction parallel to the optical axis of the LD 1. Attachment of the light emitting section 21 to the prism holder 10 is performed by fitting the hole 2c and the stepped rotating shaft 11 together. The positioning of the light emitting unit 21 in the optical axis direction is determined when the light emitting unit 21 contacts the step of the stepped rotary shaft 11. Further, the stepped rotating shaft 11 has L
While the torsion coil spring 4 is inserted and compressed from the outside of the D base 2, the E ring 5 is attached to the stepped rotary shaft 11 from the outside thereof. Further, the rotation end of the torsion coil spring 4 in the winding direction of the spring is locked by the projection 16 of the prism holder 10 and the notch 2d of the LD base.
For this reason, although a force for rotating the LD base 2 around the stepped rotation shaft 11 acts, the rotation is regulated by the actuator 6. By moving the shaft 6a of the actuator 6 in the axial direction, the light emitting unit 21 can be rotated around the stepped rotation shaft 11. That is, the light emitting section 21 can be driven to rotate about an axis parallel to the optical axis of the LD 1.

As described above, the light emitting portions 21 to 24 are provided on the prism holder 10 with the stepped rotating shafts 11 to 11 near the respective optical axes.
It is attached so as to be rotatable around 14. For this reason, even when one of the four LDs of the light emitting units 21 to 24 is deteriorated due to the life or the like and a predetermined light emission amount cannot be obtained, the problem L can be obtained without replacing the entire light source unit.
The function can be restored by replacing only the light emitting unit provided with D. This has the advantage of reducing costs associated with repair.

The four light beams emitted from the light emitting portions 21 to 24 are formed into a predetermined shape by four apertures 30 for forming light beams. The four apertures 30 are formed on the aperture plate 25, and their relative positional relationship is maintained constant. As described above, the aperture plate 25 does not change its posture even by the rotation of the light emitting units 21 to 24, and each light beam after passing through the aperture 30 maintains the parallelism with the scanning lens. A desired beam diameter can be accurately obtained on the surface to be scanned. The aperture plate 25 is housed and fixed together with the prism 26 in the recess 15 of the prism holder 10.

The four LDs are arranged on the same plane with the pn junction surfaces coincident. The light beams emitted from the light emitting units 21 and 22 pass through the aperture plate 25, enter the prism 26, are internally reflected by the inclined surface 26a, are reflected by the polarization beam splitter surface 26b of the prism 26, and are reflected by the prism 26. Is emitted. Further, the light beams emitted from the light emitting units 23 and 24 pass through the aperture plate 25, and the polarization plane thereof is rotated by 90 ° by the half-wave plate 27, and passes through the polarization beam splitter surface 26 b of the prism 26. . FIG. 5 is a diagram when this state is viewed from another angle. As described above, the light beams emitted from the four LDs become four light beams A to D, and the prism 26
Is emitted from. At this time, since the four light beams come to a predetermined position on the surface to be scanned, the light beams are emitted at slightly different emission angles or positions at the emission position of the prism 26. Each chain line indicates the traveling direction of the light beam.

The method of arranging the plurality of light beams will be described later. Light source unit 40 for emitting these four light beams
Is incorporated in a writing unit of a device such as a laser printer as shown in FIG. The four laser beams emitted from the light source unit 40 are repeatedly deflected and scanned in the main scanning direction by the rotary polygon mirror 41, and are incident on the fθ lens 42. fθ
The lens 42 converts the scanning laser light into a constant speed linear scan. Further, the four laser beams reflected by the mirror 43 and passed through the toroidal lens 44 are scanned on the photoconductor 45 as four scanning lines. Rotating polygon mirror 4
1, fθ lens 42, mirror 43, toroidal lens 4
The optical scanning devices 4 are collectively referred to as optical scanning devices, which are installed and fixed in a common housing (not shown). The light source unit is detachably attached to the housing at a predetermined position. At this time, by determining one of the beams as a reference beam and determining the position of the other beam in the sub-scanning direction, adjustment errors between the beams do not accumulate, and a high-quality image can be obtained.

The reference beam can be fixed with screws 50 or the like as shown in FIG. 4 without changing the position of the light emitting section, so that the position fluctuation of the reference beam can be reduced. Thereby, a change in the positional relationship with another beam is reduced, and the accuracy of the beam position in the sub-scanning direction is improved. For example, when the beam from the light emitting unit 24 is used as a reference beam, a screw is cut at the tip of the stepped rotary shaft 14 and a fixing screw 50 is screwed into the screw to fix the light source unit 24.

Next, the actual arrangement of the LDs will be described. FIGS. 6A and 6B show an arrangement and an adjustment method of the LD in the invention according to claim 4, which is an embodiment in which two light emitting units are provided. The light beams emitted from LD ₁ and LD ₂ are reflected by prism 26 and cylinder lens 6.
0, polygon mirror 41, scanning optical systems 42, 43, 44
And reaches the surface to be scanned of the photoconductor 45. The component configuration may be any of the light emitting units 21 and 23 or 22 and 24 in FIG. LD ₁ and LD ₂ are arranged apart from each other in the sub-scanning direction, but the beam emission positions in the sub-scanning direction coincide with each other due to the prism 26 as a beam combining means. The positions in the main scanning direction are the same. At this time, when the LD ₁ is moved in the sub-scanning direction using the above-described rotary drive mechanism, the incident position of the light beam 1 of the LD ₁ on the cylinder lens 60 changes, and the cylinder lens 60
A slight angle is created when the light is emitted from By utilizing this effect, the pitch of the two beams is adjusted by driving the LD ₁ to rotate. The solid line moves to the dotted line. The symbol + in FIG. 6B corresponds to the position of the rotation center of the light emitting unit.

FIGS. 7A and 7B show the arrangement and adjustment method of the LD according to the fifth and sixth aspects of the present invention. By adjusting the relative positional relationship between the LD and the collimating lens 3, the light beam is incident on the optical system at a predetermined angle in the main scanning direction. At this time, the light beam of the LD ₁ and LD ₂ has an angle α symmetrically with respect to the optical axis. LD ₃ and LD ₄ have an angle β symmetrically with respect to the optical axis. The angles α and β can be changed by adjusting the amount of eccentricity between the LD and the axis of the collimating lens. LD ₁ and LD _2, LD ₃ and LD ₄ is being installed apart in the sub-scanning direction, the light beams are combined by the prism, the sub-scanning direction are at the same positions. By setting the angles α and β to different angles, the positions of the light beams in the main scanning direction do not overlap, and the light beams are arranged in a line at a predetermined interval in the main scanning direction. This state is shown in FIG.
As shown in the figure, when each of the light beams arranged in a line is driven to rotate by using the actuator 6 which is the above-described rotation mechanism, angle components α and β in the main scanning direction are generated as angle components in the sub-scanning direction. come. As a result, the light beam moves in the sub-scanning direction, and the rotation angle is adjusted.
One light beam pitch. Further, since the light beams are arranged at intervals in the main scanning direction, synchronization detection for determining the writing start timing can be individually performed for each light beam, and a high-quality image can be formed.

[0026]

Advantageous effects of the present invention as a whole: (1) High-speed writing can be performed by using a multi-beam (two or more beams can be used). (2) Cost is reduced because optical components such as a prism are not used to change the sub-scanning position of the beam. (3) The work of adjusting the relative position of the light beam in the sub-scanning direction is simplified, and the work efficiency is improved.

According to the first aspect of the present invention, the positions of a plurality of light beams in the sub-scanning direction can be independently changed, so that the adjustment operation time can be reduced. Also, when the LD breaks down (when the light is no longer emitted due to its life or breakage), since the unit in which the LD and the collimating lens are integrated is independent of the light source device, only the broken unit needs to be replaced. And the repair cost can be reduced.

According to the second aspect of the present invention, since the light source device has a structure detachable from the housing of the optical scanning device,
The arrangement of the beams in the light source device can be adjusted, and the optical axis alignment work after the replacement of the light source device becomes unnecessary.

According to the third aspect of the present invention, the sub-scanning positions of a plurality of LD lights can be independently changed, and the adjustment work can be performed efficiently. Effects on Claims 4 and 5: The arrangement of a plurality of LDs can be easily adjusted and set reliably.

According to a sixth aspect of the present invention, by changing the emission angle in the main scanning direction for each of the plurality of LD lights arranged in the sub-scanning direction, the plurality of LD lights are spaced in the main scanning direction on the surface to be scanned. Therefore, the synchronization detection for determining the write start timing for each LD light can be detected independently, and a high-quality image can be obtained.

According to the seventh aspect of the present invention, by fixing the light emitting portion of the reference light beam to the holding member, the fluctuation of the position of the reference beam due to environmental fluctuations and the like is reduced, and the position of another beam position with reference to the reference beam is reduced. Accuracy also increases. As a result, a high-quality image can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a light source unit of a multi-beam light source device according to the present invention.

FIG. 2 is an assembly view of a light source unit.

FIG. 3 is a diagram showing a writing unit of a laser printer or the like to which the multi-beam light source device of the present invention is applied.

FIG. 4 is an assembly view showing a state where a part of the light emitting unit in the light source unit is fixed.

FIG. 5 is a diagram showing a state of a light beam of a multi light beam emitted from a light emitting unit.

FIG. 6 is a diagram for explaining an example of an arrangement of LDs and an adjustment method thereof.

FIG. 7 is a view for explaining another example of an arrangement of LDs and an adjustment method thereof.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... LD, 2 ... LD base, 2a ... LD base fitting hole, 2b ... LD base projection, 2c ... hole, 2d ... LD base notch, 3 ... Collimate lens, 4 ... Coil spring, 5 ... E ring , 6 ... actuator, 6a ... actuator shaft, 10 ... holding member (prism holder),
Reference numerals 11 to 14: stepped rotating shaft, 15: concave portion of prism holder, 16: projection of prism holder, 21 to 24: light emitting portion, 25: aperture plate, 26: beam combining means (prism), 26a: inclined surface, 26b ... Polarizing beam splitter surface, 27 ... 1/2 wavelength plate, 30 ... Aperture, 40 ...
Light source unit, 41: rotating polygon mirror, 42: fθ lens, 43:
Mirror, 44 ... Toroidal lens, 45 ... Photoconductor, 50
... fixing screw, 60 ... cylinder lens.

Claims (7)

[Claims] 1. A plurality of light-emitting portions integrally holding a semiconductor laser and a collimating lens for converting a semiconductor laser beam into a parallel light beam, and the parallel light beams from the plurality of light-emitting portions in the sub-scanning direction are emitted in a close state. Beam combining means,
And a means for changing an arrangement position of the light emitting unit with respect to the beam combining means. 2. The multi-beam light source device according to claim 1, wherein said plurality of light emitting units are detachably held by a same holding member. 3. The multi-beam light source device according to claim 1, wherein the means for changing the arrangement of the light emitting unit is a means for driving the light emitting unit to rotate about a rotation axis decentered from the optical axis. A multi-beam light source device. 4. The multi-beam light source device according to claim 1, wherein the plurality of light-emitting portions arranged in the sub-scanning direction have the same emission position in the main scanning direction of each semiconductor laser beam. A multi-beam light source device, characterized in that: 5. The multi-beam light source device according to claim 1, wherein an emission direction of the semiconductor laser light of each of the plurality of light emitting units arranged in the sub-scanning direction is a predetermined direction in the main scanning direction. Characterized by having an angle,
Multi-beam light source device. 6. The multi-beam light source device according to claim 5, wherein the predetermined angle can be changed for each of the plurality of light emitting units arranged in the sub-scanning direction. Light source device. 7. The multi-beam light source device according to claim 1, wherein one of the plurality of light-emitting units is used as a reference beam, the position of the plurality of light-emitting units is restrained and the other beam is used. A multi-beam light source device, which performs correction relative to a reference beam.