JP2000214402A - Light source device for multibeam scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce the deterioration of image quality caused by the vibration of a light source unit in a multibeam scanner. SOLUTION: This device is equipped with a light source unit 600 provided with plural light emitting parts 101 and 102, beam synthesizing means 103, 104, 1051 and 1052 synthesizing beams from the light emitting parts and a casing equipped with them and provided with a cylindrical emitting part 71 for emitting the synthesized beam to project from a main body, a supporting member 90 in which the emitting part 71 of the unit 600 is fit and which supports the unit 600, engaging means 74 and 75 engaging the unit 600 with the member 90 so as to rotate around the axis AX of the emitting part 71, fixing means 96 and 97 fixing the unit 600 in the immobile member 95 of the multibeam scanner through the member 90, and an elastic pressuring means pressing a casing main body to the supporting member and making elastic force for the damping of the casing main body act.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light source device for a multi-beam scanning device.

[0002]

2. Description of the Related Art A plurality of beams from a plurality of light emitting units are guided to a surface to be scanned via a common optical system, and are focused as a plurality of spots separated from each other in a sub-scanning direction. A multi-beam scanning apparatus of a type in which a plurality of beams are simultaneously deflected by an optical deflector and a plurality of lines are simultaneously scanned by the plurality of spots is being realized. As a light source device of such a multi-beam scanning device, a plurality of light emitting units and a beam combining unit are held in a casing, beams from the respective light emitting units are combined by a beam combining unit, and the combined beams are combined in the casing. A light source unit is configured to emit light from a cylindrical emission portion formed in the light source unit, and the cylindrical emission portion of the light source unit is fitted to a support member. There has been proposed a configuration in which the support member is rotatable around an axis, and the support member is fixed to a stationary member (such as a wall portion of an optical system housing) of a multi-beam scanning device. The plurality of beams emitted from the light source device are guided to a surface to be scanned (substantially, a photosensitive surface of a photoconductive photoconductor) via a common optical system, and form a plurality of light spots separated from each other. . Since the light source unit is rotatable around the axis of the cylindrical emission unit, the rotation adjustment of the light source unit makes it possible to adjust the distance between the light spots on the surface to be scanned in the sub-scanning direction. 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 unit are provided in the main body of the casing, and the cylindrical emission part is formed so as to protrude from the casing main body. Therefore, the center of gravity of the light source unit exists in the casing main body. The light source unit is supported by the support member at the cylindrical emission portion. However, since the light source unit needs to be given a degree of freedom of rotation, it cannot be said that the support member firmly holds the light source unit firmly. . Therefore, when vibration is applied to the support member from the stationary member side, an oscillating torque acts on the light source unit due to inertial force acting on the center of gravity of the light source unit, and the light source unit swings around the support portion. Will be moved. This swing causes the direction of the beam emitted from the light source unit to swing, so that the position of each light spot on the surface to be scanned vibrates. Such vibrational fluctuation of the light spot causes "banding" in an image recorded by the multi-beam scanning, and causes deterioration of the image quality of the recorded image. In particular,
Image quality degradation is conspicuous in a recorded image portion where highlights are light.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to effectively reduce image quality deterioration due to vibration of the light source unit in a multi-beam scanning device.

[0004]

According to a light source device of the present invention, a plurality of beams from a plurality of light-emitting portions are guided to a surface to be scanned through a common optical system, and are separated from each other in a sub-scanning direction. A multi-beam scanning apparatus that simultaneously deflects a plurality of beams by an optical deflector included in the optical system and simultaneously scans a plurality of lines with a plurality of spots. " . This light source device has a light source unit, a support member, an engaging means, a fixing means, and an elastic pressing means (claim 1). The “light source unit” includes a plurality of light emitting units,
It has beam combining means and a casing. The “plurality of light emitting units” emit a beam from each of them. "Beam combining means" is means for combining a plurality of beams emitted from a plurality of light emitting units. The “casing” is provided with the plurality of light emitting units and the beam combining unit, and has a cylindrical emitting unit for emitting the combined beam so as to protrude from the main body. The “support member” is a member that supports the light source unit, and is fitted with the emission part of the light source unit. The "engaging means" is means for engaging the light source unit with the supporting member so as to be rotatable around the axis of the emission unit. The “fixing unit” is a unit that fixes the light source unit to an immovable member of the multi-beam scanning device via a support member. The “plate-like immovable member” is a side wall of the optical system housing or the like. "Elastic pressing means" presses the casing body against the support member,
This is a means for applying an elastic force for damping the casing body.

In the light source device according to the first aspect of the present invention, the elastic force of the elastic pressing means is set such that “the attenuation rate of the transfer function between the casing body and the support member increases in a predetermined frequency range”. (Claim 2). in this case,
The predetermined frequency range can be "a range of approximately 200 to 300 Hz" (claim 3). As the plurality of light source units, a “semiconductor laser array in which a plurality of light emission sources are monolithically arranged” can be used. Also, "two semiconductor lasers are used as a plurality of light source units, two coupling lenses provided corresponding to each of the two semiconductor lasers are used as beam combining means, and each semiconductor laser is used by using polarized light. And a beam combining prism means for combining beams from the laser. " Of course, three or more semiconductor lasers may be used as the plurality of light source units, and these may be combined by an appropriate beam combining unit. In the light source device according to the fourth aspect, a control board for controlling the two semiconductor lasers can be integrated with the casing (claim 5). The control board may be formed separately from the casing, and the semiconductor laser disposed in the casing and the control board may be connected by a flexible conductive wire. If the light source device including the control board can be made compact, and the light source unit including the control board can be independently assembled as a light source unit, the multi-beam scanning device can be easily assembled. In the light source device according to any one of claims 1 to 5, various elastic force acting means such as a coil spring and a rubber material can be used as the elastic pressing means. The elastic pressure means can be configured as a "leaf spring for applying an elastic force therebetween" (claim 6).

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a light source device of 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 scanned surface with two beams. FIG.
6A, reference numeral 600 denotes a “light source unit”, reference numeral 90 denotes a “supporting member”, reference numeral 95 denotes a plate-shaped “immobile 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-shaped “substrate portion” whose longitudinal direction is a direction perpendicular to the drawing, and a shelf shape protruding from the (right side in the drawing) surface of the plate-shaped substrate portion. The two semiconductor lasers 101 and 102 as light sources are fitted into and fixed to mounting holes formed in the substrate from the left side in the drawing. The mounting hole penetrates the substrate portion, and the beam from the light emitting section of the semiconductor laser 101 or 102 passes through the mounting hole and is emitted to the shelf 61 side. The shelf 61 holds the coupling lenses 103 and 104, the beam combining prism 1052, and the aperture AP on a shelf parallel to the drawing. Beams emitted from the semiconductor lasers 101 and 102 and having passed through the mounting holes in the “substrate unit” 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 enters the combining prism 1052, passes through a polarization splitting film 1053 (defined so that the laser beam from the semiconductor laser 101 becomes P-polarized), and is combined with the combining prism 1052. When the light exits from the beam 1052 and passes through the aperture AP, the beam periphery is shielded from light 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 to change the polarization direction to 9 beams.
The light is rotated by 0 degrees, becomes S-polarized light with respect to the polarization separation film 1053, enters the synthesis prism 1052, is totally reflected by the prism surface, is reflected by the polarization separation film 1053, exits from the synthesis prism 1052, and has an aperture AP.
And the beam is shaped. The above-mentioned half-wave plate 105
1 and the combining prism 1052 constitute a “beam combining prism means”, and these are coupled with the coupling lenses 101 and 1.
02 constitutes "beam combining means". The “control board” indicated by reference numeral 610 is the semiconductor laser 101,
It is for controlling the control unit 102 and is integrated with the holder 60. Thus, the holder 60 having the semiconductor lasers 101 and 102, the beam combining means, and the aperture AP is provided.
Are combined with the case 70 and fixed to the case 70. The case 70 has a cylindrical emitting portion 71 for emitting the combined beam, and has an exit portion provided with a の for converting the polarization state of each combined and emitted beam into circularly polarized light. The wave plate 80 is adhered and fixed. The holder 60 and the case 70 constitute a “casing”. The axis of the cylindrical emission section 71 formed so as to protrude from the main body of the case 70 is the combined optical axis AX of the coupling lenses 103 and 104 combined by the “beam combining means” (the light matched by combining). Axis).

The support member 90 is a plate-shaped "bracket". The cylindrical injection portion 71 is rotatably fitted in a fitting hole of the bracket 90. A stop ring 74 is fixed to the tip of the injection section 71, and a compressive spring 75 is interposed between the stop ring 74 and the bracket 90. Therefore, the elastic force of the spring 75 causes the casing 70 of the casing to move.
The bracket 90 acts so as to be pressed against the right side of the figure. Due to this pressing force, the case 70 is brought into contact with the contact portions 72, 73.
It comes into pressure contact with the bracket 90 by the above method. Contact part is 3 in total
But one of them is not shown in the figure. Therefore, the contact of the case 70 with the bracket 90 is “three-point support”. Retaining ring 74, spring 75 and contact portion 72,
Reference numeral 73 denotes “the light source unit, the support member 90, and the axis of the emission unit 71 (the combined optical axis of each coupling lens).
An engagement means that is rotatable around the AX is configured. In this manner, the casing can be rotated about the optical axis AX (the axis of the emission section 71), whereby the amount of separation of the two light spots on the surface to be scanned in the sub-scanning direction can be adjusted. , "Writing density can be changed by changing the line interval in the sub-scanning direction, or the line interval can be adjusted".

The bracket 90 is fixed to the side wall 95 of the optical system housing, which is a "movable member of the multi-beam scanning device". The bracket 90 is screwed to the side wall 95 at three points. Two of these three “screw fastening parts” are “normal screw fastening parts” and are not shown. The remaining one screw fastening portion is inclined with respect to the wall surface of the side wall portion 95 as shown in the figure, and is screwed to this inclined portion with the screw 97 via the wedge 96. By doing so, the position of the wedge 96 is adjusted in the vertical direction in the drawing, so that the bracket 9
Since the “direction of the casing” can be adjusted in the drawing by 0, the direction of the optical axis AX can be adjusted in the plane of the drawing. This adjustment is performed so that the optical axis of the cylindrical lens 12 matches the optical axis AX. The screw fastening section,
The wedge 96, the screw 97 and the like constitute "fixing means". The elastic pressing means 201, as shown in FIG.
A leaf spring bent at 0 degrees, one end of which is screwed to the bent portion at the upper end of the bracket 90 with the screw 99, and the contact projection 202 (formed by punching) of the other end is formed into a case. The case 75 is pressed against the bracket 90 by being pressed against the contact portion 75 formed on the upper part of the case 70. Since there is some play in fitting the emission portion 71 in the bracket 90, it is the elastic force of the spring 75 and the leaf spring 201 that locks the light source unit to the bracket 90. The center of gravity of the light source unit: G is at the position shown in the figure,
The action of gravity causes a counterclockwise torque to act on the light source unit around point P. If there is no leaf spring 201, the above torque must be supported only by the elastic force of the spring 75, and when vibration from the immobile member side is transmitted,
It is difficult to prevent resonance of the light source unit with only the spring 75. In this embodiment, the elastic force of the leaf spring 201 acts on the light source unit to increase the pressing force of the light source unit on the support member 95 of the casing body, thereby preventing the light source unit from vibrating.

That is, the light source device shown in the embodiment of FIG. 1A has a plurality of light emitting units 101 and 102 and beam combining means 103, 104 and 1 for combining beams from each light emitting unit.
A light source unit 600 comprising: a plurality of light-emitting units 051 and 1052; And a support member 90 fitted with the light emitting unit 71 to support the light source unit, and a light source unit 600
The light source unit 600 is fixed to the immovable member 95 of the multi-beam scanning device via engagement means 72, 73, 74, and 75 which are rotatably engaged around the axis of the emission unit 71 with respect to the light emitting unit 71. And an elastic pressing means 201 for pressing the casing body against the support member 95 to apply an elastic force for damping the casing body (claim 1). Further, the plurality of light source units are two semiconductor lasers 101 and 102, and the beam combining unit includes:
It has two coupling lenses 103 and 104 provided corresponding to each of the two semiconductor lasers, and beam combining prism means 1051 and 1052 for combining beams from the respective semiconductor lasers using polarized light. (Claim 4), 2
Control board 6 for controlling semiconductor lasers 101 and 102
10 is integrated with the casing (claim 5),
The elastic pressing means 201 is a leaf spring for applying an elastic force between the upper part of the casing main body and the support member 95 (claim 6). By appropriately setting the elastic force of the leaf spring, high-frequency vibration of the light source unit can be suppressed, and the above-mentioned banding can be effectively reduced. The strength of the elastic force applied by the elastic pressing means should basically be determined experimentally according to each specific case. In FIG. 1, each combined beam forms a long linear image in the main scanning direction near the deflecting and reflecting surface of the optical deflector by the cylindrical lens 12, and is deflected at an equal angular velocity by the optical deflector. , And a light spot is condensed on the surface to be scanned by a scanning image forming optical system such as an fθ lens, and two lines on the surface to be scanned are simultaneously scanned.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS When a multi-beam scanning device is incorporated in an image forming apparatus such as a digital copying machine or an optical printer, a resonance point of an optical housing, a vibration source of a driving system in a visualization process, and transfer sheet transfer Most of the vibration frequency of the excitation source of the system is concentrated in a region of about 200 to 300 Hz. Therefore, the vibration of the light source device is controlled by setting the elastic force of the elastic pressing means so that the attenuation rate of the transfer function between the casing body and the support member becomes large in the frequency range of approximately 200 to 300 Hz. (Claim 3).

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 in the figure. Further, as shown in FIG. 1B, the distance from the fixed portion of the leaf spring 201 as the elastic pressing means to the bent portion is x, the distance from the bent portion to the contact protrusion 202 is y,
The vertical distance between the center of gravity G and the contact protrusion 202 is represented by z.

As a specific example, X = 20 mm, Y = 7 m
m, x = 10 mm, y = 8 mm, and z = 18 mm.
The elastic force of the spring 75 was set to F = 0.2 kgwt.
As the leaf spring 201 of the embodiment, thickness: 0.2 mm, width:
A stainless steel plate having a length of 50 mm and a length of 25 mm is bent at substantially 90 degrees to form a spring constant: K = 1.4 kg.
w / cm elastic force: F (large) was set to 0.4 Kgwt. Further, as the leaf spring 201 of the comparative example, a thickness: 0.1
mm, width: 50 mm, length: 25 mm, formed by bending a stainless steel plate at approximately 90 degrees, and a spring constant: K =
0.7 Kgw / cm elasticity: F (small) = 0.2 Kgwt
Set to. In the above, the width: 50 mm corresponds to FIG.
FIG. 1B shows the width of the plate in a direction orthogonal to the drawing, and FIG.
Length appearing in (b): larger than 25 mm, abutting protrusion 2
Numeral 02 is formed at two places in a direction orthogonal to the drawing of FIG. 1B, and the interval between these two contact portions is approximately 35 mm. A measurement result of the acceleration-to-acceleration transfer function in the vertical direction of the vibration transmitted from the plate-like stationary member 95 to the light source unit via the support member 90 when an elastic force is applied by these two types of leaf springs. Is shown in FIG. The vertical axis is “transfer function” in dB, and the horizontal axis is frequency: Hz.
0 dB or more indicates that the acceleration of vibration is amplified, and 0 dB
B or less means that the acceleration of the vibration is attenuated. As is clear from the figure, the elastic force of the comparative example: F (small) = 0.
In the case of 2 Kgwt, the acceleration of vibration tends to be amplified in the range of 200 to 300 Hz, and the vibration suppression effect of the light source unit is not sufficient, but the elastic force: F (large) = 0.
In the case of 4 Kgwt, the acceleration of the vibration is substantially negative in the range of 200 to 300 Hz, which indicates that the vibration suppression effect of the light source unit is extremely good. As described above, by appropriately setting the elastic force of the elastic pressure contact means, it was possible to effectively reduce the vibration of the light source unit and effectively reduce the banding in the recorded image.

In general, the larger the elastic force of the elastic pressure contact means is, the higher the vibration damping effect is. However, if the elastic force is set too large, a large force is required to adjust the rotation of the light source unit. An appropriate elastic force is preferably set in consideration of the ease of rotation adjustment of the light source unit.

[0014]

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, as described above, the vibration of the light source unit is effectively suppressed, so that 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 describing one embodiment of the present invention.

FIG. 2 is a diagram for explaining the effect of the elastic pressure contact means in the embodiment.

[Explanation of symbols]

 Reference Signs List 600 light source unit 90 support member 95 plate-like immovable member 201 leaf spring (elastic pressing means)

Claims (6)

[Claims] A plurality of light-emitting portions; a beam combining means for combining beams from the light-emitting portions; and a plurality of light-emitting portions and a beam combining means. A light source unit having a casing having an emission portion protruding from the main body, a support member fitted with the emission portion of the light source unit, and supporting the light source unit; Engaging means for rotatably engaging about the axis of the emission unit; fixing means for fixing the light source unit to a stationary member of a multi-beam scanning device via the support member; and supporting the casing body A light source device for a multi-beam scanning device, comprising: elastic pressing means for pressing against a member to apply an elastic force for damping a casing body. 2. The light source device according to claim 1, wherein the elastic force of said elastic pressing means is set such that the attenuation rate of the transfer function between the casing body and the support member becomes large in a predetermined frequency range. A light source device for a multi-beam scanning device, comprising: 3. The light source device for a multi-beam scanning device according to claim 2, wherein the predetermined frequency range is in a range of approximately 200 to 300 Hz. 4. The light source device according to claim 1, wherein the plurality of light source units are two semiconductor lasers, and the beam combining means is provided corresponding to each of the two semiconductor lasers. A light source device for a multi-beam scanning device, comprising: two coupling lenses; and beam combining prism means for combining beams from the respective semiconductor lasers using polarized light. 5. The light source device according to claim 4, wherein a control board for controlling the two semiconductor lasers is integrated with a casing. 6. The light source device according to claim 1, wherein the elastic pressing means is a leaf spring for applying an elastic force between an upper portion of the casing main body and the support member. Light source device of the multi-beam scanning device.