JP2000028885A - Light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device having pitch accuracy to which strict accuracy is required and excellent in ambient temperature resistance without enhancing the accuracy of the position of the light emitting point of a semiconductor laser. SOLUTION: When the position of the light emitting point 2a of a semiconductor laser 2 is deviated from the center O of the outside shape of the laser 2, lens supporting parts are arranged so that relative positional relation between the position of one of a lens supporting part 1b and the position of the light emitting point 2a of one of the laser 2 may be equal to that between the position of the other lens supporting part 1b and the position of the light emitting point 2a of the other laser 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device using a semiconductor laser used in a digital copying machine or a laser printer.

[0002]

2. Description of the Related Art In a light source device using a semiconductor laser, the directionality (position of an optical axis) of laser light emitted from the light source device and the parallelism (collimation characteristic) of a light beam are required as optical characteristics. Furthermore, in digital copiers and laser printers, as a matter of course, with a light source device that simultaneously scans a plurality of lines for the purpose of speeding up printing and switching pixel density, a plurality of semiconductor lasers and collimator lenses are used.
Although a plurality of laser beams are generated, the pitch accuracy in the laser optical axis pitch direction (the pitch accuracy in the row direction, ie, the y direction in FIG. 5) is required to be particularly stricter than each laser optical axis position.

Accordingly, the present applicant has previously filed Japanese Patent Application No. 9-881.
As No. 36, a light source device in which the influence of adhesive curing shrinkage was prevented was proposed.

FIG. 5 is an exploded perspective view of a light source device previously filed by the present applicant. The base 1 has two fitting holes 1a, 1a.
Having. Two semiconductor lasers 2, 2 for irradiating laser light are press-fitted and fixed to the back surfaces of the fitting holes 1a, 1a.
The base 1 is located at the front surface of the fitting holes 1a, 1a for directly bonding and fixing the collimator lenses 3, 3 and has an arc-shaped lens support section having a slightly larger diameter than the outer circumference of the collimator lenses 3, 3. 1b and 1b are integrally formed concentrically with the optical axes of the semiconductor lasers 2 and 2, respectively.

[0005] The collimator lenses 3 and 3 are filled with a gap formed between the bonding surface 1c of the lens support portion 1b and the outer peripheral surface of the collimator lens 3 with, for example, an ultraviolet-curing adhesive, and then the laser light is applied. The position is adjusted so that the axis is at a predetermined position on the image writing surface, and in this state, ultraviolet rays are irradiated to the adhesive to fix the axis.

An aperture forming member 4 is a member for taking out and shaping a parallel light beam near the center of the collimator lenses 3 and 3, and the aperture 4 formed of a light beam selecting hole.
a and 4a are provided. This aperture forming member 4
Apertures 4a, 4a are set near the centers of the collimator lenses 3, 3 so as to coincide with the respective optical axes, and are fitted and fixed to holding members (not shown). The laser beam synthesizing prism 5 is also fitted into the holding member, and the base 1 is also attached to the holding member by screwing.

In such a light source device, the aperture 4
The parallel light beams emitted from a and 4a are combined into a substantially coaxial laser beam by the laser beam combining prism 5, and then guided to a scanning optical system (not shown) provided for image writing, which is provided thereafter.

[0008]

However, the above-mentioned conventional light source device has the following problems. As described above, in a light source device using a semiconductor laser,
As the optical characteristics, the directionality (optical axis position) of the laser beam emitted from the light source device and the parallelism (collimation characteristic) of the light beam are required. In a light source device that generates a plurality of laser beams by a plurality of semiconductor lasers and a collimator lens, the pitch accuracy of the direction (row direction,
In other words, particularly strict accuracy is required for the laser optical axis position pitch accuracy in the y direction in FIG.

When adjusting the position of the collimator lens described above, each collimator lens (center of the design target position) is adjusted and adjusted.
At this time, when the precision of each component is poor, the position of the collimator lens is shifted from the center of the design target position, and the bonding is performed. Here, the accuracy of each component generally varies with the position of the light emitting point of the semiconductor laser.

For example, as shown in FIG. 6, two semiconductor lasers 2 (LD1) and 2 (LD2)
If the light emitting point position 2a in 2) is largely deviated from the center O of the outer shape, the adhesive layer 6 of the collimator lens 3 on the side of the semiconductor laser 2 (LD2) is biased. In this case, even if the initial optical characteristics are satisfied, if the temperature rises in the light source device, the adhesive layer 6 on the semiconductor laser 2 (LD2) side
Of the collimator lens 3 corresponding to the semiconductor laser 2 (LD2), a moving component is generated in the pitch direction (the direction of the thick arrow in FIG. 6). Therefore, there is a problem that the resistance to environmental temperature is poor.

The light emitting point position of the semiconductor laser is manufactured so as to aim at the center value, that is, to emit light from the center position O based on the outer shape. The average value of a certain lot is set to the reference value (center value O). However, manufacturing variations occur.
However, it is very difficult to eliminate this variation, and there is a problem that reducing the variation also leads to a decrease in yield and a significant increase in cost.

Accordingly, an object of the present invention is to provide a light source device which is excellent in environmental temperature resistance at a pitch accuracy requiring strict accuracy without increasing the accuracy of a light emitting point position of a semiconductor laser.

[0013]

According to a first aspect of the present invention, there is provided a light source device comprising: a base having a pair of fitting holes penetrating through the front and back; A pair of semiconductor lasers to be fitted, a pair of collimator lenses located on the base surface and in front of the through hole and held respectively coaxially with the optical axis of the semiconductor laser, and a laser emitted from the collimator lens A pair of apertures for shaping light, a beam combining prism for combining the laser beams substantially coaxially, and a plurality of lenses for bonding and fixing a collimator lens whose position is adjusted to obtain predetermined optical characteristics to a base surface A light-emitting device including a support portion, wherein a position of one of the lens support portions and a position of one of the lens support portions are shifted when an emission point position of the semiconductor laser is deviated from a center of an outer shape of the semiconductor laser. Relative positional relationship between the semiconductor laser light emitting point position, is characterized in that arranged to be equal to the relative positional relationship between the position and the other semiconductor laser emitting point of the other lens support portion.

In this configuration, when the position of the light emitting point of the semiconductor laser is deviated from the center of the outer shape of the semiconductor laser, the relative positional relationship between the position of one lens support and the position of the one semiconductor laser light emitting point is changed. The laser light emitted from the pair of semiconductor lasers is arranged so that the pitch of the laser light emitted from the pair of semiconductor lasers changes with respect to temperature change. Also hardly changes.

According to a second aspect of the present invention, there is provided a light source device comprising: a base having a pair of fitting holes penetrating the front and back; a pair of semiconductor lasers located on the back surface of the base and fitted in the fitting holes;
A pair of collimator lenses located on the base surface and in front of the through hole and held coaxially with the optical axis of the semiconductor laser, and a pair of apertures for shaping laser light emitted from the collimator lens; A light source device comprising: a beam combining prism for combining laser beams substantially coaxially; and a plurality of lens supports for bonding and fixing a collimator lens whose position is adjusted to obtain predetermined optical characteristics to a base surface. In addition, the pair of semiconductor lasers are combined such that the light emitting points thereof are displaced in opposite directions to each other, and are fitted in a mounting direction inverted by 180 degrees.

In this configuration, the pitch of the laser light emitted from the pair of semiconductor lasers hardly changes even when the temperature changes, and the positions of the light emitting points of the respective semiconductor lasers are shifted in opposite directions. By combining the laser diodes, even if the light emitting point positions vary widely in the same lot of semiconductor lasers, even if they are greatly shifted to the plus side in the same lot, those that are greatly shifted to the minus side can be combined. Even if the lot is large, all the semiconductor lasers can be used, and an inexpensive light source device can be provided without improving the position accuracy of the light emitting point of the semiconductor laser.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of a light source device according to an embodiment of the present invention, and FIG. 2 is a schematic front view including a lens supporting portion when a collimator lens is bonded.
3 is a rear view of FIG. 2, and FIG. 4 is an enlarged view of a main part for explaining the effect of the present invention. FIG. 3A shows a case where the light emitting point position of the semiconductor laser is shifted by 180 degrees, and FIG. () Shows a case where the light emitting point position of the semiconductor laser is shifted by other than 180 degrees.

As shown in FIG. 1, the base 1 has two fitting holes 1a, 1a. Two semiconductor lasers 2, 2 for irradiating a laser beam, respectively, are press-fitted and fixed to the back surfaces of the fitting holes 1a, 1a.

Here, the two semiconductor lasers 2 are shown in FIG.
As shown in FIG. 1, the light emitting point positions 2a, 2a of the semiconductor lasers 2, 2 are combined in such a manner that the light emitting point positions 2a, 2a are displaced by the same degree in the opposite directions to each other.
As shown in FIGS. 3 and 4, they are mounted in a state of being turned 180 degrees. In FIGS. 1, 3, 4, 5, and 6, 2
b indicates a notch for indicating the mounting direction of the semiconductor laser.

As shown in FIGS. 1, 2, and 4, the base 1 is located at the front of the fitting holes 1a and 1a so as to directly adhere and fix the collimator lenses 3 and 3, respectively. Slightly larger in diameter than the outer circle of (for example,
Lens support portions 1b, 1b having an arc-shaped cross section
Are integrally formed concentrically with the optical axes of the semiconductor lasers 2 and 2, respectively. The optical axis direction (z direction) of the lens support portion 1b
The length of the collimator lens is set longer than the lens thickness in the optical axis direction (z direction) of the collimator lenses 3 and 3 so as not to adhere to other portions even when the adhesive is excessively filled.

When the collimator lenses 3 and 3 are directly fixed to the lens support 1b integrally formed on the base 1, the number of parts of the light source device can be reduced, and the light source device can be provided at low cost. be able to. further,
Since there is no intervening member such as a holder between the collimator lenses 3 and 3 and the lens supporting portions 1b and 1b, the fixing can be performed with high accuracy without being affected by manufacturing errors of the intervening member. Further, when the collimator lenses 3 and 3 are directly fixed to the lens support unit formed integrally with the base 1, a tightening unit such as a screw is eliminated, and there is no displacement of parts at the time of tightening. A light source device can be provided.

As shown in FIGS. 2 and 4, when viewed from the front, the shape of each of the lens support portions 1b, 1b is arcuate in cross section, each having a semicircle or less. It is desirable to make each section symmetrical in an arc shape in view of the nature. Further, the lens supporting portions 1b, 1b are arranged so as to be line-symmetric with respect to the center line 1f of the base 1, and the center lines C, C of the arc-shaped cross section are collimator lenses 3, 3, respectively.
The two beams emitted are set substantially perpendicular to the sub-scanning pitch direction (y direction).

When the cross section of the lens support portions 1b, 1b is configured to be an arc of a semicircle or less, the adhesive layer 6
Only covers less than half of the outer circumference of the collimator lens,
Since the curing shrinkage of the adhesive becomes directional, the initial positions of the collimator lenses 3 and 3 can be offset in anticipation of the shrinkage of the adhesive, and the positional accuracy after curing can be improved. Further, the lens support portions 1b, 1b
The curing light can be irradiated from the opening side of the collimator lenses 3 and 3 toward the side surfaces of the collimator lenses 3 and 3, and uneven curing can be further reduced.

When the lens supporting portions 1b, 1b are configured to be line-symmetric with respect to a line perpendicular to the beam pitch direction, distortion due to curing shrinkage in the beam pitch direction is offset, and the direction of curing shrinkage is equal to the beam pitch. Since the direction is limited to the direction orthogonal to the direction, the directionality of the curing shrinkage is improved, and the position can be adjusted with higher accuracy.

As shown in FIG. 2, the collimator lens 3 is gripped by chucks 7, 7 capable of adjusting the position in three axes (x, y, z) at the time of adjustment and bonding, and the lens support portions 1b, 1b It is arranged concentrically with the optical axis of each of the semiconductor lasers 2 and 2 above. Then, the bonding surface 1c of the lens support portion 1b
After a gap formed between the collimator lens 3 and the outer peripheral surface of the collimator lens 3 is filled with a light (ultraviolet) curable adhesive, the position of the collimator lens 3 is finely adjusted while inspecting optical characteristics with an inspection device (not shown). When the position at which the desired optical characteristic is obtained is determined, the chucks 7, 7 are fixed, and light (ultraviolet) is irradiated from the light (ultraviolet) irradiators 8, 8 toward the adhesive.

Since the collimator lens 3 is made of a material capable of transmitting light (ultraviolet light), the light (ultraviolet light) irradiated from the light (ultraviolet light) irradiators 8 and 8 passes through the collimator lens 3 and adheres. The adhesive is irradiated to cure the entire adhesive evenly.

This curing of the adhesive is performed for each of the two collimator lenses 3 and 3. Therefore, the thickness between the bonding surfaces 1c, 1c of the lens supporting portions 1b, 1b and the collimator lenses 3, 3 is uniform and symmetrical with respect to the gap dimension (about 0.2 mm), and the thickness direction is the sub-scanning direction. Pitch (y
Direction), the collimator lenses 3 and 3 are supported by the lens support portions 1 c and 1 c by the adhesive layer 6.
It is fixed on c while maintaining predetermined optical characteristics.

When the lens support portions 1b, 1b are formed in a circular cross section having a diameter slightly larger than the outer circumference of the collimator lenses 3, 3, the lens support portions 1b, 1b are formed.
1b and the collimator lenses 3 and 3 are arranged concentrically so that the collimator lenses 3 and 3 and the lens support portions 1b and
1b has a uniform thickness.
For this reason, the entire surface of the adhesive layer 6 is solidified uniformly, so that curing unevenness is eliminated and the displacement of the collimator lenses 3 and 3 is prevented.

When the lens supporting portions 1b, 1b are formed in a circular arc shape having a radius of curvature substantially larger than the radius of curvature of the outer peripheral circle of the collimator lenses 3, 3 by the thickness of the adhesive layer, the lens supporting portions 1b, 1b are formed. 1b and collimator lenses 3, 3
Are arranged concentrically so that the collimator lens 3,
3 and an adhesive layer 6 formed between the lens support portions 1b, 1b
Has a uniform thickness with a desired adhesive layer thickness. For this reason, the entire surface of the adhesive layer 6 is solidified uniformly, so that uneven curing is eliminated, and the displacement of the collimator lenses 3 and 3 is prevented.

As shown in FIG. 1, the aperture forming member 4
Is a member for taking out and shaping a parallel light beam near the center of the collimator lenses 3 and 3, and has apertures 4a and 4a formed of holes for selecting light beams. Apertures 4a, 4a
Are set to coincide with each optical axis. The parallel light beams emitted from the apertures 4a, 4a are combined into a substantially coaxial beam by the beam combining prism 5, and guided to a scanning optical system (not shown) for image writing disposed thereafter.

The aperture forming member 4 and the beam combining prism 5 are mounted on the base 1 by a mounting member (not shown). At this time, the two overlapping circular steps 1d and 1d of the base 1 are used for positioning, and four holes 1e are provided.
Is used for mounting.

As shown in FIG. 4, a pair of semiconductor lasers 2
In (LD1) and 2 (LD2), the light emitting point positions 2a are shifted by the same degree in the opposite directions. In this case, the semiconductor laser 2
Since (LD1) and 2 (LD2) are attached to each other by being inverted by 180 degrees, the bias of the adhesive layer is generated in the same direction in both the pair of semiconductor lasers 2 (LD1) and 2 (LD2) in the same amount. Therefore, even when the temperature rises in the light source device, the direction of position change of the collimator lens is the same direction and the amount of change is almost the same. As a result, the change in the pitch of the laser light emitted from the two collimator lenses 3 and 3 is canceled out and does not occur. Also,
Normally, the light emitting point position 2a of the semiconductor laser 2 is evenly distributed with respect to the outer center O, which is the target center. It can be said that it exists. Therefore, a light source device having excellent pitch accuracy can be obtained without increasing the accuracy of the light emitting point position 2a of the semiconductor laser 2.

According to the light source device of the above embodiment, the two semiconductor lasers 2 (LD1) and 2 (LD2) are mounted by being inverted by 180 degrees, and the light emitting point position 2 of each semiconductor laser is set.
By combining a that is shifted in the opposite direction, the deviation of the adhesive layer 6 occurs in the same direction and even if the semiconductor lasers have a large shift in the light emitting point position 2a.
Since the displacement of the two collimator lenses 3 and 3 due to temperature fluctuations is also generated in the same direction by the same amount, the pitch of the two laser beams hardly changes, and high precision with excellent environmental temperature resistance A simple light source device can be provided.

Further, two semiconductor lasers 2 (LD1),
2 (LD2) is mounted by inverting by 180 degrees, and the light emitting point positions 2a of the respective semiconductor lasers are shifted in the opposite direction. However, even if the lot is greatly shifted to the plus side in the lot, it is possible to combine those that are greatly shifted to the minus side,
All the semiconductor lasers can be used even in a lot having a large variation, so that an inexpensive light source device can be provided without improving the position accuracy of the light emitting point of the semiconductor laser.

In the above embodiment, two semiconductor lasers 2 (LD1) and 2 (LD2) are mounted by inverting 180 degrees, and the light emitting point position 2a of each semiconductor laser is shifted in the opposite direction. Has been described,
When the light emitting point position 2a of the semiconductor laser is deviated from the outer center O of the semiconductor laser, the relative positional relationship between the position of one lens support 1b and the light emitting point position 2a of one semiconductor laser is different from that of the other lens. By arranging the position of the support portion 1b so as to be equal to the relative positional relationship between the position of the other semiconductor laser emission point 2a, the bias of the adhesive layer 6 occurs to the same extent in the same direction, and 2 Since the displacements of the two collimator lenses 3 and 3 occur in the same direction by the same amount, the pitch of the two laser beams hardly changes, and a high-precision light source device excellent in environmental temperature resistance is provided. Can be provided.

The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the gist of the present invention.

[0037]

As is apparent from the above description, according to the light source device of the present invention, the pitch of the laser light emitted from the pair of semiconductor lasers hardly changes even when the temperature changes, and the environmental temperature resistance It is possible to provide a highly accurate and highly accurate light source device.

Further, according to the light source device of the present invention, by combining the light emitting point positions of the respective semiconductor lasers which are shifted in the opposite direction, it is possible that the light emitting point positions of the same lot of the semiconductor laser greatly vary. However, even if the lot greatly shifts to the plus side in the lot, it is possible to combine those that greatly shift to the minus side, so that all the semiconductor lasers can be used even in a lot with large variation, and the emission point of the semiconductor laser An inexpensive light source device can be provided without improving the positional accuracy.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a light source device according to an embodiment of the present invention.

FIG. 2 is a schematic front view including a lens supporting portion when a collimator lens is bonded.

FIG. 3 is a rear view of FIG. 2;

4A and 4B are enlarged views of a main part for explaining the effect of the present invention, wherein FIG. 4A shows a case where the light emitting point position of the semiconductor laser is shifted by 180 degrees, and FIG. It shows a case where it is shifted by other than degrees.

FIG. 5 is an exploded perspective view of a conventional light source device.

FIG. 6 is an enlarged view of a main part for describing a problem of a conventional light source device.

[Explanation of symbols]

 Reference Signs List 1 base 1a fitting hole 1b lens support 2 semiconductor laser 2a light emitting point position 3 collimator lens 4a aperture 5 beam combining prism O outer shape center

Claims (2)

[Claims] 1. A base having a pair of fitting holes penetrating the front and back sides, a pair of semiconductor lasers located on the back surface side of the base and fitted into the fitting holes, A pair of collimator lenses positioned on the front surface and held coaxially with the optical axis of the semiconductor laser, a pair of apertures for shaping the laser light emitted from the collimator lens, and for synthesizing the laser light substantially coaxially A beam combining prism, and a plurality of lens supports for bonding and fixing a collimator lens whose position has been adjusted to obtain predetermined optical characteristics to a base surface, wherein the light emitting point position of the semiconductor laser is When the semiconductor laser is deviated from the center of the outer shape, the relative positional relationship between the position of one of the lens support portions and the position of the light emitting point of one of the semiconductor lasers is changed to the other lens. A light source device, characterized in that the arranged to be equal to the relative positional relationship between the position and the other semiconductor laser emitting point of the lifting unit. 2. A base having a pair of fitting holes penetrating the front and back sides, a pair of semiconductor lasers located on the back side of the base and fitted into the fitting holes, and A pair of collimator lenses positioned on the front surface and held coaxially with the optical axis of the semiconductor laser, a pair of apertures for shaping the laser light emitted from the collimator lens, and for synthesizing the laser light substantially coaxially A beam combining prism, and a light source device including a plurality of lens supporting portions for bonding and fixing a collimator lens whose position is adjusted to obtain predetermined optical characteristics to a base surface,
The light source device according to claim 1, wherein the pair of semiconductor lasers is such that light emitting points thereof are displaced in directions opposite to each other, and are fitted in a mounting direction inverted by 180 degrees.