JP3998843B2 - Light source device for multi-beam scanning device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light source device for a multi-beam scanning device.
[0002]
[Prior art]
A plurality of beams from a plurality of light emitting sections are guided to a surface to be scanned through a common optical system, condensed as a plurality of spots separated from each other in the sub-scanning direction, and the above described optical deflector included in the optical system A multi-beam scanning apparatus that simultaneously deflects a plurality of beams and simultaneously scans a plurality of lines with the plurality of spots is being realized.
As a light source device of such a multi-beam scanning device, a plurality of light emitting sections and beam combining means are held in a casing, beams from the respective light emitting sections are combined by the beam combining means, and each combined beam is combined with the casing. The light source unit is configured to emit light from the cylindrical light emitting portion formed on the light source unit, and the cylindrical light emitting portion of the light source unit is fitted to the support member. It has been proposed that the support member is fixed to a stationary member of the multi-beam scanning device (such as a wall surface of the optical system housing) so as to be rotatable about an axis.
A plurality of beams emitted from the light source device are guided to a scanning surface (substantially, a photosensitive surface of a photoconductive photosensitive member) through a common optical system, and form a plurality of light spots separated from each other. . Since the light source unit can rotate around the axis of the cylindrical emitting portion, the interval in the sub-scanning direction of the light spots on the surface to be scanned can be adjusted by adjusting the rotation of the light source unit.
However, it has been found that such a light source device has the following problems.
That is, the light source unit and the beam combining means are provided in the main body part of the casing, and the cylindrical injection part is formed so as to protrude from the casing main body, so that the center of gravity of the light source unit exists in the casing main body. Although the light source unit is supported by the support member at the cylindrical emission portion, it is necessary to give the light source unit a degree of freedom of rotation, so the light source unit cannot be firmly and securely held by the support member. .
For this reason, when vibration is applied to the support member from the side of the stationary member, the inertial force that acts on the center of gravity of the light source unit causes vibrational torque to act on the light source unit, thereby swinging the light source unit around the support portion. Will be moved. This swinging swings the direction of the beam emitted from the light source unit, and the position of each light spot on the surface to be scanned fluctuates.
Such vibration fluctuation of the light spot becomes “banding” in an image recorded by multi-beam scanning, and causes deterioration in image quality of the recorded image. In particular, the image quality deterioration is conspicuous in the recorded image portion where the highlight is light.
[0003]
[Problems to be solved by the invention]
It is an object of the present invention to effectively reduce image quality degradation caused by vibration of the light source unit in a multi-beam scanning device.
[0004]
[Means for Solving the Problems]
According to the light source device of the present invention, “a plurality of beams from a plurality of light emitting units are guided to a surface to be scanned through a common optical system and condensed as a plurality of spots separated from each other in the sub-scanning direction. The light source device emits a plurality of beams in a “multi-beam scanning device of a type in which a plurality of beams are simultaneously deflected by an included optical deflector and a plurality of lines are simultaneously scanned by a plurality of spots”.
The light source device includes a light source unit, and the support member, and the engagement means, and fixing means, the elastic pressure means (claim 1).
"Light source unit" includes a plurality of light emitting portions, and the beam combining means, and a casing.
The “plurality of light emitting units” emit beams from each of them.
The “beam combining unit” is a unit that combines a plurality of beams emitted from a plurality of light emitting units.
The “casing” is equipped with the plurality of light emitting portions and beam combining means, and has a cylindrical injection portion for emitting the combined beam so as to protrude from the casing body.
The “support member” is a member that supports the light source unit so as to be rotatable about the optical axis of the beam emitted from the emission part, and the emission part is fitted therein.
The “engaging means” is means including means for generating an elastic force for press- fitting the light source unit to the support member.
“Fixing means” is means for fixing the light source unit to the stationary member of the multi-beam scanning device via a support member.
The “non-moving member” is a side wall portion or the like of the optical system housing.
The “elastic pressing means” is a means different from the means for generating the elastic force, which presses the casing body against the support member and applies an elastic force for damping the casing body.
[0005]
In the light source apparatus according to the first aspect, the elastic force of the elastic pressure means set as "a substantially negative in the frequency domain of the transfer function is Jo Tokoro vibration between the casing body and the support member" it is preferable to (claim 2). In this case, the predetermined frequency region can be set to “a range of about 200 to 300 Hz” (Claim 3).
A “semiconductor laser array in which a plurality of light emitting sources are arranged in a monolithic array” can also be used as the plurality of light emitting units.
Further, "using the two semiconductor lasers as a plurality of light emitting portions, two coupling lenses provided corresponding to the beam combining means into two semiconductor lasers and the beam from the two semiconductor laser It is also possible to have a beam synthesis prism means for synthesizing using the polarized light . Of course, three or more semiconductor lasers may be used as the plurality of light emitting units, and these may be combined by appropriate beam combining means.
In the light source device according to claim 4, the control board for controlling the two semiconductor lasers can be integrated with the casing (claim 5). The control board to the casing and separate, between the semiconductor laser and the control board deployed in the casing may be connected by a flexible conductor, but as according to claim 5, integrated control board to the casing it can be made compact braking light source apparatus control board also included if so assembled independently as a light source unit including a control board, the assembly of the multi-beam scanning device is facilitated.
The light source device according to any one of the claims 1-5, a coil spring or a rubber material such as the elastic pressing means, can be utilized various elastic force acting means, between the "casing the body and the support member An elastic pressurizing means can be configured as a “plate spring for applying an elastic force to” (claim 6).
[0006]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a light source device for a multi-beam scanning device according to the present invention will be described with reference to FIG. The light source device shown in this embodiment is used as a light source device of a two-beam type multi-beam scanning device that simultaneously scans a surface to be scanned with two beams.
In FIG. 1A, reference numeral 600 denotes a “light source unit”, reference numeral 90 denotes a “support member”, reference numeral 95 denotes a plate- like “non-moving member”, and reference numeral 201 denotes an “elastic pressing unit”.
The light source unit 600 is configured as follows. The “holder” indicated by reference numeral 60 is a plate-like “substrate portion” whose longitudinal direction is the direction orthogonal to the drawing, and a shelf shape that protrudes like a shelf from the (right side in the drawing) surface of this plate-like substrate portion. The two semiconductor lasers 101 and 102 as the light source are fitted and fixed from the left surface of the drawing in the mounting holes formed in the substrate portion. The mounting hole penetrates the substrate portion, and the beams from the light emitting portions of the semiconductor lasers 101 and 102 pass through the mounting hole and are emitted to the shelf-shaped portion 61 side. The shelf-like portion 61 holds the coupling lenses 103 and 104, the beam combining prism 1052, and the aperture AP on a shelf surface parallel to the drawing.
The beams emitted from the semiconductor lasers 101 and 102 and passing through the mounting holes of the “substrate part” enter the coupling lenses 103 and 104, respectively, and are converted into parallel beams. The beam converted into a parallel beam by the coupling lens 103 is incident on the combining prism 1052, and passes through the polarization separation film 1053 (determined so that the laser beam from the semiconductor laser 101 becomes P-polarized light) to be transmitted to the combining prism. When exiting from 1052 and passing through the aperture AP, the beam periphery is shielded and the beam is shaped. The beam converted into a parallel beam by the coupling lens 104 is transmitted through a half-wave plate 1051 bonded and integrated with the combining prism 1052 and rotated in the polarization direction by 90 degrees, and is converted into S-polarized light with respect to the polarization separation film 1053. Then, the light enters the combining prism 1052, is totally reflected by the prism surface, is reflected by the polarization separation film 1053, exits from the combining prism 1052, passes through the aperture AP, and is shaped into a beam. The aforementioned half-wave plate 1051 and the synthetic prism 1052 constitutes the "beam combining prism means", and these and the coupling lens 103 and 104 constitute a "beam combining means."
A “control board” denoted by reference numeral 610 is for controlling the semiconductor lasers 101 and 102 and is integrated with the holder 60.
Thus, the holder 60 having the semiconductor laser 101 and the beam combining means and the aperture AP is combined with the case 70, is fixed to the case 70. Case 70 has a cylindrical injection portion 71 for injection of the combined beam, 1/4 for at its outlet portion for converting the polarization state of each beam emitted made if the circularly polarized light A wave plate 80 is bonded and fixed. The holder 60 and the case 70 constitute a “casing”. The axis of the cylindrical emitting portion 71 formed so as to protrude from the main body portion of the case 70 is the combined optical axis AX of the coupling lenses 103 and 104 combined by the “beam combining means” (light matched by combining). Axis).
[0007]
The support member 90 is a plate-like “bracket”.
The cylindrical injection portion 71 is rotatably fitted in the fitting hole of the bracket 90.
A stop ring 74 is fixed to the tip of the injection portion 71, and a compressible spring 75 is interposed between the stop ring 74 and the bracket 90. Thus the elastic force of the spring 75 acts to press the casing of the case 70 from the left side of the figure the bracket 90. Due to this pressure contact force, the case 70 is pressed against the bracket 90 by the contact portions 72, 73 and the like. There are a total of three abutments, one of which does not appear in the figure. Therefore, the contact of the case 70 with the bracket 90 is “three-point support”. The retaining ring 74, the spring 75, the contact portions 72, 73, etc. constitute “ an engaging means including means for generating an elastic force for press- fitting the light source unit 600 to the support member 90”.
With the above-described configuration, the casing can be rotated about the optical axis AX (the axis of the emission unit 71), and thereby the amount of separation of the two light spots on the scanned surface in the sub-scanning direction can be adjusted. , “The line density in the sub-scanning direction can be changed to change the writing density, or the line interval can be adjusted”.
[0008]
The bracket 90 is fixed to the side wall portion 95 of the optical system housing which is “a stationary member of the multi-beam scanning device”. The bracket 90 is screwed to the side wall portion 95 at three points. Two of these three “screw fastening portions” are “normal screw fastening portions” and are not shown. One screwed portion remaining is inclined with respect to the wall surface of the side wall portion 95 as shown, is screwed with screws 97 to the wedge 96 is interposed the inclined portion. In this way, by adjusting the position of the wedge 96 in the vertical direction in the drawing, the “casing direction” can be adjusted in the drawing by the bracket 90, so that the direction of the optical axis AX can be adjusted in the drawing. This adjustment is performed so that the optical axis of the cylindrical lens 12 matches the optical axis AX.
The screw fastening portion, the wedge 96, the screw 97, and the like constitute “fixing means”.
Elastic pressure means 201, as shown in FIG. 1 (b), an elastic plate a plate spring which is bent 90 degrees, is screwed by screws 99 to the folded portion of the upper end of the bracket 90 to one end , by pressing the contact portion 76 contacting projections 202 (which is formed by stamping) formed in the upper portion of the to case 70 of the other end, and is pressed against the casing 70 to the bracket 90.
Since the fitting of the injection portion 71 of the bracket 90 there is some play, to engage the light source unit to the bracket 90 is an elastic force of the bar ne 75 and the leaf spring 201. The center of gravity G of the light source unit is at the position of FIG, gravity exerts a counterclockwise torque around the pair Shi point P to the light source unit. If, when there is no leaf spring 201, without must support the torque only by the elastic force of the spring 75, the optical resonance source unit to prevent only the spring 75 when the vibration is transmitted from the stationary member side is difficult. In this embodiment, increasing the pressing force to the support member 95 of the casing body in the light source unit by the action of the elastic force of the leaf spring 201 to the light source unit is to prevent vibration of the light source unit.
[0009]
1A includes a plurality of light emitting units 101 and 102, beam combining units 103, 104, 1051, and 1052 that combine beams from the respective light emitting units, and a plurality of light emitting units. It is equipped with the parts and the beam combining means, a light source unit 600 and a casing 60, 70 having a cylindrical injection portion 71 for injection of the combined beam to project from the casing main body, the light source unit 600 The light emitting unit 71 is fitted, and the light source unit 600 is supported so as to be rotatable about the optical axis AX, and the engaging means 72 and 73 are configured to press and engage the light source unit 600 with the support member 90. 74, 75, fixing means 96, 97 for fixing the light source unit 600 to the stationary member 95 of the multi-beam scanning device via the support member 90, and the casing It presses the body against the support member 90, and an elastic pressure means 201 for preventing the vibration of the light source unit 600 with the engaging means 72, 73, 74, 75 (claim 1).
Further, the plurality of light emitting units are two semiconductor lasers 101 and 102, and the beam combining means includes two coupling lenses 103 and 104 provided corresponding to the two semiconductor lasers 101 and 102 , respectively. Beam combining prism means 1051 and 1052 for combining beams from the respective semiconductor lasers 101 and 102 using polarized light (Claim 4). A control substrate 610 for controlling the two semiconductor lasers 101 and 102 is a casing. The elastic pressure means 201 is a leaf spring that applies an elastic force between the casing body and the support member 90 (Claim 6).
By appropriately setting the elastic force of the leaf spring, the above-mentioned banding can be effectively reduced by suppressing the high frequency vibration of the light source unit.
The strength of the elastic force applied by the elastic pressurizing means should basically be determined experimentally according to specific individual cases.
In FIG. 1, each synthesized beam is formed as a long line image in the main scanning direction in the vicinity of the deflection reflection surface of the optical deflector by the cylindrical lens 12, and is deflected at an equal angular velocity by the optical deflector. The light is condensed as a light spot on the surface to be scanned by a scanning imaging optical system such as the above, and two lines on the surface to be scanned are simultaneously scanned.
[0010]
【Example】
When incorporating a multibeam scanning apparatus in an image forming apparatus such as a digital copying machine or an optical printer, the vibration source of the drive system at the resonance point and the sensible Zoka process of the optical housing, pressurizing the transfer sheet conveying system excitation source Are mostly concentrated in the region of approximately 200 to 300 Hz. Therefore, by the transfer function of the vibration between the casing body and the support member, to set the elastic force of the elastic pressing means so as to be substantially negative in the frequency region of approximately 200 to 300 Hz, the light source apparatus Can be controlled (claim 3).
[0011]
In the embodiment shown in FIG. 1A, the total mass of the light source unit (including the control board 600) is approximately 80 g. In FIG. 1, the distance between the swing center P and the center of gravity G is X in the horizontal direction and Y in the vertical direction as shown.
Further, as shown in FIG. 1B, the distance from the fixed portion of the leaf spring 201, which is an elastic pressure means, to the bent portion is x, the distance from the bent portion to the contact protrusion 202 is y, and the center of gravity The vertical distance between G and the contact protrusion 202 is z.
[0012]
As specific examples, X = 20 mm, Y = 7 mm, x = 10 mm, y = 8 mm, and z = 18 mm. Further, the elastic force of the spring 75 was set to F = 0.2 kgwt.
As the leaf spring 201 of the embodiment, a stainless steel plate having a thickness of 0.2 mm, a width: 50 mm, and a length: 25 mm is formed by bending at about 90 degrees, and a spring constant: K = 1.4 Kgw / cm 2 , Elastic force: F (large) was set to 0.4 kgwt.
Further, as the leaf spring 201 of the comparative example, a stainless steel plate having a thickness of 0.1 mm, a width: 50 mm, and a length: 25 mm is bent at approximately 90 degrees, and a spring constant: K = 0.7 Kgw / cm 2 , elastic force: F (small) = 0.2 kgwt.
In the above, the width: 50 mm is the plate width in the direction orthogonal to the drawing in FIG. 1B, the length appearing in FIG. 1B is larger than 25 mm, and the contact protrusion 202 is shown in FIG. Two portions are formed in a direction orthogonal to the drawing of b), and the distance between these two contact portions is approximately 35 mm.
When an elastic force is applied by these two types of leaf springs, the transfer function of acceleration vs. acceleration in the vertical direction of vibration transmitted from the plate-like stationary member 95 to the light source unit 600 via the support member 90 was measured. The results are shown in FIG. The vertical axis is “transfer function” in dB, the horizontal axis is frequency: Hz, 0 dB or more indicates that the vibration acceleration is amplified, and 0 dB or less means that the vibration acceleration is attenuated. As can be seen, elastic force of the Comparative Example: in the case of F (small) = 0.2Kgwt is in the region of 200~300Hz is in acceleration amplification tendency of vibration damping effect of the light source unit 600 Although not sufficient, elastic force of the example: If the F (large) = 0.4Kgwt the acceleration of vibration in the area of 200~300Hz is substantially negative, very good damping effect of the light source unit 600 It shows that there is. As described above, by appropriately setting the elastic force of the elastic pressure unit 201 , the vibration of the light source unit 600 can be effectively reduced, and the banding in the recorded image can be effectively reduced.
[0013]
Although the elastic force of the elastic pressure means high generally greater nearly as vibration control effect, since to require a large force when the elastic force is set too modest to rotational adjustment of the light source unit, the light source unit it is preferable to set the proper person elastic force in view of the ease of rotation adjustment.
[0014]
【The invention's effect】
As described above, according to the present invention, a novel light source device in a multi-beam scanning device can be realized. In the light source device of the present invention, since the vibration of the light source unit is effectively suppressed as described above, the banding of the recorded image due to the vibration of the light source unit can be effectively reduced.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining one embodiment of the present invention.
FIG. 2 is a diagram for explaining the effect of elastic pressing means in the embodiment.
[Explanation of symbols]
600 light source unit 90 support member 95 plate-like stationary member 201 leaf spring (elastic pressure means)

Claims (6)

A light source unit comprising a casing having a plurality of light emitting sections and a beam combining means for combining beams from the plurality of light emitting sections, and having a cylindrical emitting section for emitting the combined beams protruding from the casing body;
A support member that rotatably supports the light source unit around the optical axis of the beam emitted from the emission unit;
Engagement means including means for generating an elastic force for pressingly engaging the light source unit with the support member;
Fixing means for fixing the support member to the immovable member;
The casing body is pressed against the support member by one end and the other end is fixed to the support member in pressure contact with the casing body, possess a different resilient pressurizing means from the means for generating the elastic force,
The light source device of the multi-beam scanning apparatus, wherein the light source unit is prevented from vibrating together with the engaging means by the pressing force of the casing main body against the support member by the elastic pressure means . The light source device according to claim 1,
The multi-beam scanning characterized in that the elastic force of the elastic pressing means is set so that the transfer function of vibration between the casing body and the support member is substantially negative in a predetermined frequency region. Light source device of the device. The light source device according to claim 2,
The light source device of the multi-beam scanning device, wherein the predetermined frequency region is in a range of approximately 200 to 300 Hz. The light source device according to any one of claims 1 to 3,
The plurality of light emitting units are two semiconductor lasers, and the beam synthesizing means includes two coupling lenses provided corresponding to the two semiconductor lasers, and each beam from the two semiconductor lasers. And a beam combining prism means for combining the light beams using polarized light. The light source device according to claim 4,
A light source device for a multi-beam scanning device, wherein a control board for controlling the two semiconductor lasers is integrated with the casing. The light source device according to any one of claims 1 to 5,
A light source device for a multi-beam scanning device, wherein the elastic pressure means is a leaf spring that applies an elastic force between the casing body and the support member.

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