JP2005274678A - Optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make compatible original alignment of an optical scanner and alignment of a photodetection means by ensuring performance of an optical system while maintaining compactness. <P>SOLUTION: An optical scanner is disclosed in which there are disposed in order a light source 12 with a monitor where a VCSEL light source part 26 where a number of light emission points are arranged in a line and a single photosensor 28 for receiving a plurality of laser beams LB emitted from the plurality of light emission points are formed on the same substrate 30, a collimate lens 14, a half mirror 16, a polygon mirror front lens, a polygon mirror, a polygon mirror rear lens and a photoreceptor. In the optical scanner, the laser beams LB transmitted through the half mirror 16 are used to expose the photoreceptor, and the laser beams LB reflected on the half mirror 16 are converged again on the photosensor 28 by the collimate lens 14. The photosensor 28 singly receives all the plurality of laser beams LB emitted from the VCSEL light source part 26. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical scanning device.

  Unlike the edge emitting laser, the surface emitting laser (VCSEL) does not emit a beam emitted from the back surface (so-called back beam). Therefore, a part of the emitted light is separated by a half mirror or the like, and the separated beam is detected by light detection means. It is necessary to detect the amount of light.

  As the method, there is a method described in Patent Document 1.

  In many configurations, the beam from the light source is separated by a half mirror or the like, and the beam reaches the photodetector via an independent optical path. For example, in the apparatus of Patent Document 1, the beam separated by the half mirror is used. Is again passed through the collimator lens, and the beam is incident on the same number of light sensors as the light source in the same package as the light source.

  In another prior art, a lens for condensing the beam separated by the half mirror on the optical sensor is required separately. However, in the apparatus of Patent Document 1, the collimating lens also serves as the lens for condensing the optical sensor. The number of points is reduced, and there is an advantage that it can be made compact.

In addition, since the folding angle of the half mirror is small, there is also an advantage that the fluctuation of the half mirror reflectivity due to the deflection direction instability, which is a problem specific to the surface emitting laser, does not occur.
Japanese Patent Application Laid-Open No. 10-1000047

However, the apparatus of Patent Document 1 uses the same number of photoanalyzers as the light sources, and thus has the following problems.
(1) The optical sensor is disposed adjacent to the light emitting point.

The interval between a plurality of light emitting points used in an optical scanning device is often used at a few tens of μm to 100 μm. However, it is difficult to accurately arrange the photodiodes between the minute intervals, and it is difficult to mount the light emitting points. If the interval is not increased as compared with the conventional case, it cannot be configured. If the interval between the light emitting points is increased, the distance between the light emitting point and the optical axis increases, and it becomes difficult to ensure the performance of the optical system.
(2) The light receiving area of the optical sensor is small.

  Since the light receiving area of the optical sensor is small, the shape and position accuracy of the collimating lens and the half mirror must be strict in order for the beam to reliably enter the light receiving surface.

  However, in an optical scanning device, the alignment of the beam is generally adjusted with the aim of a polygon mirror or a folding mirror arranged after the half mirror, so there is a possibility that the original alignment and the alignment to the optical sensor may not be compatible. .

  If the light receiving area is increased in order to allow the misalignment, the problem described in the above problem (1) increases.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical scanning apparatus capable of solving the above problems while maintaining the compactness of the conventional apparatus.

  The optical scanning device according to claim 1 includes a base member including a plurality of light emitting points that emit light beams, and a single light detecting unit that receives a plurality of light beams emitted from the light emitting points. Optical means positioned on the optical path of the plurality of light beams emitted from the plurality of light emitting points and configured and arranged to make the plurality of light beams substantially parallel light, and the plurality of light beams The scanning medium to be exposed in step (b) is positioned on the path of the plurality of light beams that have passed through the optical means, and the plurality of light beams are configured and arranged to scan between both ends of the scanning medium. A scanning means, and disposed between the optical means and the scanning means, and transmits a part of the light beam and reflects the remaining part; projects the transmitted part onto the scanning means; one Is characterized in that it comprises a beam back member having a function of returning to the single optical detection means via said optical means.

  Next, the operation of the optical scanning device according to claim 1 will be described.

  In the optical scanning device according to the first aspect, the light beam emitted from each of the plurality of light emitting points is made into substantially parallel light by the optical system and enters the beam returning member.

  In the beam returning member, a part of the light beam is transmitted, the remaining part is reflected, and the transmitted part is projected onto the scanning means.

  The scanning means scans the projected light beam onto the scanned medium and performs exposure.

  On the other hand, the plurality of light beams reflected by the beam returning member are returned to a single light detecting means.

  By monitoring the light beam with the light detection means, it is possible to adjust the intensity of the light beam applied to the scanned medium.

  In addition, since the light detection means used in the optical scanning device of the present invention is configured to receive a plurality of light beams emitted from a plurality of light emitting points, for example, a minute detection unit adapted to the beam diameter. As compared with the case where a plurality of photodiodes are accurately arranged, the structure is simplified.

  In addition, since it is not necessary to increase the interval between the light emitting points for light detection, the distance between the light emitting point and the optical axis of the optical means can be reduced, and the performance of the optical means can be easily ensured.

  Furthermore, since the light detection means configured to receive a plurality of light beams has a large light receiving area, the collimating lens and the half mirror are arranged with a plurality of minute photodiodes that match the beam diameter. The accuracy is not required so much as in the conventional example, and the adjustment etc. becomes easy, and the alignment of the beam aimed at the polygon mirror and the folding mirror arranged after the half mirror is adjusted, and the light beam incident on the light detection means Adjustment is compatible.

  According to a second aspect of the present invention, in the optical scanning device according to the first aspect, a distance between the beam returning member and the optical means is set to be equal to or less than a focal length of the optical means.

  Next, the operation of the optical scanning device according to claim 2 will be described.

  By setting the distance between the beam returning member and the optical means to be equal to or less than the focal length of the optical means, the light beam reflected by the beam returning member and directed to the light detecting means can be brought closer to the optical axis side of the optical means. The size of the optical means can be reduced.

  According to a third aspect of the present invention, in the optical scanning device according to the first or second aspect, the single photodetecting means has a size capable of receiving all the beams returned by the beam returning member. And the detection surface is arranged laterally with respect to the light emitting point of the light source with respect to the longitudinal direction of the array.

  Next, the operation of the optical scanning device according to claim 3 will be described.

  For example, when a plurality of light emitting points are arranged in one direction, the detection surface of the light detection means has an elongated shape along one direction according to the arrangement of the light emitting points.

  Therefore, when the light emitting points arranged in a row and the elongated detection surface are arranged in series, a base member that is long in one direction is required.

  In the optical scanning device according to claim 3, the detection surface is arranged laterally with respect to the longitudinal direction of the array with respect to the plurality of light emitting points, that is, the light emitting points arranged in a line and the long length. Since the shape detection surface is in parallel, the overall length of the base member is suppressed, and the apparatus can be compactly assembled.

  According to a fourth aspect of the present invention, in the optical scanning device according to any one of the first to third aspects, the optical means includes a collimating lens, and the light beam emitted from the light emitting point is the collimating lens. The light beam returned by the beam return member passes through the outer peripheral side of the collimating lens.

  Next, the operation of the optical scanning device according to claim 4 will be described.

  By passing the light beam emitted from the light emitting point through the vicinity of the optical axis of the collimating lens, the light beam necessary for image formation can use a portion having good performance in the collimating lens.

  Note that the light beam that is returned by the beam returning member and directed to the light detection means is only used for light amount detection, and only needs to be applied to the light detection means. It is not necessary to use a portion with good performance.

  As described above, according to the present invention, as in a surface emitting laser, in an optical scanning device that needs to control a light quantity by separating a part of an emitted beam and guiding the beam to a light detection unit. Thus, it becomes possible to detect the light quantity with a more compact and simpler configuration than the prior art.

[First Embodiment]
Hereinafter, an optical scanning device 10 according to a first embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the optical scanning device 10 of the present embodiment includes a light source 12 with a monitor, a collimating lens 14, a half mirror 16, a polygon mirror front lens 18, a polygon mirror 20, a polygon mirror rear lens 22, and a photoreceptor 24. I have.

  As shown in FIG. 2A, the monitor-equipped light source 12 includes a VCSEL light source unit 26 in which a large number (four in this embodiment) of light emitting points 26A are arranged in a row, and a plurality of light emitted from a plurality of light emitting points 26A. A single optical sensor 28 that receives the laser beam LB is formed on the same substrate 30.

  The optical sensor 28 has a single light receiving surface, and is set to a size that can receive all emitted laser beams LB (one row, illustrated by dotted circles). In this embodiment, the light receiving surface is rectangular. And are arranged in series with the plurality of light emitting points 26A.

  As shown in FIG. 3, a plurality of laser beams LB emitted from the VCSEL light source unit 26 (only the optical axis is shown in the drawing. Each beam is divergent light) are substantially collimated by the collimating lens 14. It is said.

  The optical axes of the laser beams LB intersect at the focal position of the collimating lens 14.

  A half mirror 16 that reflects part of the laser beam LB is disposed at the focal position of the collimating lens 14.

  As shown in FIG. 1, the laser beam LB transmitted through the half mirror 16 is used for exposure of the photosensitive member 24 via the polygon mirror front lens 18, the polygon mirror 20, and the polygon mirror rear lens 22.

On the other hand, the laser beam LB reflected by the half mirror 16 is condensed again on the optical sensor 28 by the collimator lens 14 (note that the optical axes of the plurality of beams are parallel to each other).
(Function)
Next, the operation of the optical scanning device 10 of this embodiment will be described.

  In the optical scanning device 10, laser beams LB (diverged light) emitted from a plurality of light emitting points 26 </ b> A of the VCSEL light source unit 26 are made substantially parallel light by the collimator lens 14 and enter the half mirror 16.

  The laser beam LB transmitted through the half mirror 16 is projected onto the photoconductor 24 through the polygon mirror front lens 18, the polygon mirror 20, and the polygon mirror rear lens 22.

  The laser beam LB is scanned on the photosensitive member 24 by the polygon mirror 20.

  On the other hand, the laser beam LB reflected by the half mirror 16 is returned to the single optical sensor 28 and used for light quantity control.

  Since the single optical sensor 28 receives all of the plurality of laser beams LB emitted from the plurality of light emitting points 26A, for example, compared with a conventional device in which a plurality of minute photodiodes matching the beam diameter are accurately arranged. Thus, the structure can be simplified.

  Further, since it is not necessary to widen the interval between the light emitting points 26A for light detection, the laser beam LB emitted from the light emitting point 26A can be brought close to the optical axis of the collimating lens 14, and the optical performance of the collimating lens 14 is achieved. Therefore, it is easy to secure the performance of the collimating lens 14.

  Further, since the light receiving area of the optical sensor 28 is set large, the shape and position of the collimating lens 14 and the half mirror 16 are more accurate than the conventional example in which a plurality of minute photodiodes corresponding to the beam diameter are arranged. This is not so required, and the adjustment and the like are facilitated, and the alignment adjustment of the beam aiming at the polygon mirror 20 and the like arranged after the half mirror and the adjustment of the laser beam LB incident on the optical sensor 28 can be compatible. .

  Note that the position of the half mirror 16 is not limited to the focal position of the collimating lens 14, and may be closer to the collimating lens 14 than the focal position as shown in FIG. .

However, as can be seen from FIG. 5, when the half mirror 16 is moved away from the focal position of the collimating lens 14, the beam reflected by the half mirror 16 approaches the outer end side of the collimating lens 14 (as compared with FIG. 3). ) Since the distance between the plurality of beams further increases, the collimating lens 14 must be enlarged in order to prevent vignetting due to the lens opening. From the point of view of the size of the collimating lens 14, half as shown in FIG. It is better to arrange the mirror 16 on the collimating lens side (including the focal position) than the focal position of the collimating lens 14, and the distance between the collimating lens 14 and the half mirror 16 is about the focal length of the collimating lens 14. 1/2 is good (Because the beam intersects at the collimating lens 14, the lens surface Use range is the minimum). That is, in the arrangement of FIG. 4, the collimating lens 14 can be reduced in size.
[Second Embodiment]
Next, a second embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.

  FIG. 6 is a development of FIG. 3, but as shown in FIG. 6, the half mirror 16 is set at an angle different from 90 ° with respect to the optical axis of the laser beam LB whose reflecting surface is transmitted through the collimator lens 14. When arranged, the light emitted from the VCSEL light source unit 26 can be arranged at the center of the optical axis of the collimating lens 14, and the aberration is reduced as compared with the case where the outside of the optical axis of the collimating lens 14 as shown in FIGS. (Relative to the photoreceptor 24), or restrictions on lens design can be relaxed.

  For the laser beam LB returning to the optical sensor 28, the collimating lens 14 only condenses the beam, so the imaging performance does not need to be considered so much. As shown in FIG. It is not necessary for the laser beam LB emitted from the laser beam LB and the laser beam LB returning to the optical sensor 28 to pass through the symmetrical position of the collimating lens 14.

  In the case of the configuration of the present invention, it is desirable that the distance S (between the centers) between the VCSEL light source unit 26 and the optical sensor 28 is short.

If this distance S is long, the use range of the collimating lens surface becomes large, so that the collimating lens 14 needs to be enlarged.
[Third Embodiment]
Next, a second embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the same structure as embodiment mentioned above, and the description is abbreviate | omitted.

  FIG. 2B shows a case where the optical sensor 28 is arranged in parallel to the VCSEL light source unit 26 in which the four light emitting points 26A shown in FIG. 2A are arranged in a row. .

  As apparent from FIG. 2B, the distance S between the VCSEL light source unit 26 and the optical sensor 28 can be shortened by arranging them in parallel.

  By shortening the distance S, not only the size of the collimating lens 14 but also the size of the substrate 30 to which the VCSEL light source unit 26 and the optical sensor 28 are attached can be reduced, so that the configuration is made more compact. Can do.

  Here, the light emitting points 26A arranged in one row have been described. However, even if the light emitting points 26A are arranged two-dimensionally (for example, in a matrix form), the optical sensors 28 are arranged in parallel to the longitudinal direction. Needless to say, the effects of the present invention can be obtained by arranging.

1 is a schematic configuration diagram of an optical scanning device according to an embodiment. (A) is a top view of the light source with a monitor of the optical scanning device which concerns on 1st Embodiment, (B) is a top view of the light source with a monitor of the optical scanning device which concerns on 3rd Embodiment. It is a side view of the optical system between a light source with a monitor and a half mirror. It is a side view of the optical system between a light source with a monitor and a half mirror. It is a side view of the optical system between a light source with a monitor and a half mirror. It is a side view of the optical system from the light source with a monitor to the half mirror of the optical scanning device according to the second embodiment.

Explanation of symbols

10 optical scanning device 14 collimating lens (optical means)
16 Half mirror (beam return member)
20 Polygon mirror (scanning means)
24 photoconductor (scanned medium)
26A Light emission point 28 Optical sensor (light detection means)
30 Substrate (base member)

Claims (4)

A plurality of light emitting points that emit light beams, and a base member that includes a single light detection means that receives a plurality of light beams emitted from the light emitting points.
Optical means positioned on the optical path of the plurality of light beams emitted from the plurality of light emitting points and configured and arranged to make the plurality of light beams substantially parallel light;
A scanned medium exposed with a plurality of the light beams;
Scanning means positioned on the path of the plurality of light beams that have passed through the optical means, and configured and arranged so that the plurality of light beams scan between both ends of the scanned medium;
It is disposed between the optical means and the scanning means, transmits a part of the light beam and reflects the remaining part, projects the transmitted part onto the scanning means, and transmits the remaining reflected part to the scanning means. A beam returning member having a function of returning to the single light detecting means via an optical means;
An optical scanning device comprising:   2. The optical scanning device according to claim 1, wherein a distance between the beam returning member and the optical unit is equal to or less than a focal length of the optical unit.   The single light detection means has a detection surface having a size capable of receiving all the beams returned by the beam return member, and the detection surface is arranged in an array with respect to the light emitting point of the light source. The optical scanning device according to claim 1, wherein the optical scanning device is disposed laterally with respect to the longitudinal direction. The optical means comprises a collimating lens;
The light beam emitted from the light emitting point passes through the vicinity of the optical axis of the collimating lens, and the light beam returned by the beam returning member passes through the outer peripheral side of the collimating lens. 4. The optical scanning device according to any one of items 3.

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