JP2000075227A - Multi-beam light source device - Google Patents

Abstract

(57) Abstract: In a method using two semiconductor laser arrays, the position of a beam spot array between the semiconductor laser arrays can be freely adjusted, and this adjustment can be performed easily and reliably. SOLUTION: First and second semiconductor laser arrays 11 and 12 each having a plurality of light emitting points on a straight line are integrally held together with a pair of first and second collimator lenses 12 and 13, respectively. A support member 15 disposed on the first and second emission axes a1 and a2 separated by a predetermined angle in the scanning direction;
The support member 15 is held by a holder member 19 that is rotatable about the optical axis C of the scanning optical system, and the holder member 19 is rotatable about the optical axis C of the scanning optical system. It is possible to adjust the sub-scanning relative position between the beam spot arrays by the light emitting points of the first and second semiconductor laser arrays 11 and 12 by a simple operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to an optical writing / scanning apparatus of an image forming apparatus such as a digital copying machine or a laser printer, and in particular, simultaneously scans a surface to be scanned such as a photoreceptor with a plurality of laser beams. The present invention relates to a multi-beam light source device used for performing the above operation.

[0002]

2. Description of the Related Art In general, as a method of improving a recording speed in an optical scanning device used in an optical writing system, there is a method of increasing a rotation speed of a polygon mirror as a deflecting means. However, in this method, durability, noise, vibration, laser modulation speed, and the like of the polygon motor are problematic, and there is a limit in improving the recording speed.

Therefore, a multi-beam scanning apparatus has been proposed in which a plurality of laser beams are scanned at one time to simultaneously record a plurality of recording lines. For example, JP-A-56-4
As disclosed in Japanese Patent No. 2248, a semiconductor laser array in which a plurality of light emitting sources (light emitting points) are monolithically arranged in an array is used as a light source.

Normally, the light output of a semiconductor laser is detected by utilizing the scanning time outside the image area for each scanning line, and the amount of applied current is set by feedback control. In the semiconductor laser array as in the above-mentioned publication example, although there are a plurality of light sources (light emitting points), the sensor for detecting the light output is common, so that the output setting from the detection of the light output to the feedback has to be performed in time series. Not get. Therefore, as the number of light sources in the semiconductor laser array increases, the time required for this processing increases, and there is a high possibility that the scanning time outside the image area for each scan will not be enough. If not, the above processing is performed using the scanning time between pages. However, in this case, the set applied current amount must be held for a long time, during which the laser output fluctuates. The image density may change.

In this regard, according to Japanese Patent Application Laid-Open No. 7-72407, laser beams emitted from a plurality of light emitting sources of a plurality of semiconductor laser arrays are combined using a beam combining means such as a prism, and one laser beam is formed. A multi-beam light source unit configured to emit a plurality of laser beams from a light source has been proposed. According to this, since the number of light emitting points required for one semiconductor laser array can be halved, the processing time required for detecting the light output of these light emitting points and setting the light output by feedback control is also reduced. Can be halved. Therefore, it is possible to obtain a high-quality image while minimizing the fluctuation of the image density.

[0006]

In each of the plurality of semiconductor laser arrays, a single collimator lens is provided for a plurality of light emitting points, and the laser light from each light emitting point is converted into a parallel light beam. , Into the scanning optical system.
Here, the adjacent pitch of the beam spot array is determined by the sub-scanning magnification of the entire scanning optical system.

However, according to the method disclosed in Japanese Patent Application Laid-Open No. 7-72407, a combination of a plurality of semiconductor laser arrays, a corresponding collimator lens, and a beam synthesizing means is used to combine each semiconductor laser array synthesized by a beam splitter in a prism. In order to suppress the deviation of the relative position of the beam spot array within an allowable value, it depends only on the alignment accuracy of the emission axis and the angular accuracy of the beam splitter surface and the reflecting surface of the prism, and there is a problem in mass productivity. .

In view of the above, in the present invention, in a system using two semiconductor laser arrays, the alignment of a beam spot array between the semiconductor laser arrays can be adjusted freely, and this adjustment can be performed easily and reliably, and the assembling efficiency can be improved. It is an object of the present invention to provide an improved multi-beam light source device.

Further, the present invention provides a multi-beam light source device capable of achieving the above object with higher accuracy.

[0010]

According to the first aspect of the present invention,
A first semiconductor laser array having a plurality of light-emitting points on a straight line, a second semiconductor laser array having the same structure as the first semiconductor laser, and a laser beam emitted from the first semiconductor laser array. A first collimator lens for coupling, a second collimator lens for coupling laser light emitted from the second semiconductor laser array, the first semiconductor laser array and the first coupling lens, Are arranged on a first emission axis, and the second semiconductor laser array and the second coupling lens are separated by a predetermined angle in the main scanning direction with respect to the first emission axis. A support member disposed above to hold these members integrally, and a plurality of laser beams emitted from the first and second semiconductor laser arrays are scanned to scan the surface to be scanned. Comprising a holder member for holding the support member to the optical axis of the scanning optical system for forming a Musupotto by turning adjustably provided as the pivot center, the.

Therefore, the first and the first operations are simply performed by simply rotating the holder member about the optical axis of the scanning optical system.
It is possible to adjust the relative position in the sub-scanning between the beam spot arrays by the light emitting points of the two semiconductor laser arrays, thereby improving the assembling efficiency.

According to a second aspect of the present invention, there is provided a first semiconductor laser array having a plurality of light emitting points on a straight line;
A second semiconductor laser array having the same structure as that of the first semiconductor laser array, a first collimator lens for coupling the laser light emitted from the first semiconductor laser array, and an emission from the second semiconductor laser array A second collimator lens for coupling a laser beam;
A first support member for forming a first light source section by arranging the semiconductor laser array and the first coupling lens on a first emission axis and integrally holding the semiconductor laser array; and the second semiconductor laser An array and the second coupling lens
And a plurality of laser beams emitted from the first and second semiconductor laser arrays by scanning a plurality of laser beams emitted from the first and second semiconductor laser arrays. Beam synthesizing means for emitting the plurality of laser beams close to each other in the sub-scanning direction with respect to the optical axis of the scanning optical system for forming a beam spot on the surface to be scanned; and rotating the optical axis of the scanning optical system. The first support member and the second support member are provided so as to be freely rotatable as a center of movement, and are separated from the first ejection shaft and the second ejection shaft by a predetermined angle with respect to the main scanning direction. And a holder member for integrally holding the beam combining means.

Therefore, even in the system using the beam combining means, the first and second semiconductor laser arrays can be simply adjusted by rotating the holder member about the optical axis of the scanning optical system. It is possible to adjust the relative position in the sub-scanning between the beam spot arrays by each light emitting point, thereby improving the assembling efficiency.

According to a third aspect of the present invention, in the multi-beam light source device according to the second aspect, the first and second support members rotate about the corresponding first and second emission axes, respectively. It is held by the holder member so as to be adjustable in motion.

Accordingly, the sub-scanning pitch in the beam spot arrays of the first and second semiconductor laser arrays can be individually adjusted, and higher precision can be achieved, so that higher quality image recording can be performed.

According to a fourth aspect of the present invention, there is provided the multi-beam light source device according to the first or second aspect, wherein the first and second light sources are provided.
A plurality of light-emitting points in the semiconductor laser array are arranged in the sub-scanning direction, and the distance between the first and second emission axes on the surface to be scanned is set to be at least twice the pitch of adjacent recording lines. Become.

Therefore, after adjusting the relative position in the sub-scanning direction between the beam spot rows of the semiconductor laser array, the change in the sub-scanning pitch in the beam spot row can be suppressed to an allowable value, and high precision can be achieved. High quality image recording becomes possible.

[0018]

FIG. 1 shows a first embodiment of the present invention.
A description will be given with reference to FIG. First, as an assumption of the present embodiment, an image forming relationship when a semiconductor laser array is used will be described with reference to FIGS. Figure 1 shows 2
FIG. 3 is an explanatory diagram of an optical system showing a relationship between a light emitting point pitch Ps of a semiconductor laser array 1 having two light emitting points 1a and 1b and a sub-scanning pitch Ps ′ on a scanned surface (an image surface such as a photoreceptor surface) 2; f indicates the focal length of the collimator lens 3. 4
Denotes a scanning optical system having a sub-scanning magnification βs. Here, in order to obtain a predetermined sub-scanning pitch Ps 'on the surface 2 to be scanned, Ps = Ps' / βs on the light source surface of the semiconductor laser array 1, and the sub-scanning magnification βs is set according to the recording pitch. Become.

Here, the semiconductor laser array 1 has a relatively narrow light emitting point pitch such that the pitch Ps = P between the two light emitting points 1a and 1b, which is shown in FIG.
As shown in FIG. 2B, a method of arranging in the sub-scanning direction and a method in which the pitch Ps between the two light emitting points 1a and 1b is relatively wide are used. 1a, 1b) by tilting the angle θ to P · sin θ =
There is a method of arranging so as to be Ps. The present invention
Although it can be applied to any of the methods, here, an example of application to the former method is described for the sake of simplicity.

Under such a premise, a configuration example of the present embodiment will be described with reference to FIGS. FIG. 3 is an exploded perspective view of the multi-beam light source device of the present embodiment, and FIG. 4 is a longitudinal sectional side view in an assembled state. In the present embodiment, two semiconductor laser arrays 11, each having two light emitting points,
12 (first and second semiconductor laser arrays). These semiconductor laser arrays 11 and 12 have the same structure. Further, the semiconductor laser arrays 11 and 12 form a pair, and collimator lenses 13 and 14 (first and second collimators) 13 and 14 for coupling outgoing light as parallel light to a scanning optical system.
Is provided.

A support member 15 for integrally holding these members (semiconductor laser arrays 11, 12 and collimator lenses 13, 14) is provided. This support member 1
Reference numeral 5 denotes an aluminum die-cast, and two stepped fitting holes 16 for press-fitting and supporting the semiconductor laser arrays 11 and 12 are formed on the back side thereof in parallel at an interval of 8 mm in the main scanning direction. ing. Here, the semiconductor laser arrays 11 and 12 are attached to these fitting holes 16 in such a manner that two light emitting points are oriented in the sub-scanning direction. Further, U-shaped supporting portions 17a and 17b for supporting the lens are formed in the center of the front side of the supporting member 15 in the fitting holes 16 continuously. Here, positioning in the sub-scanning direction is performed so that two light emitting points are symmetrically arranged with respect to each of the emission axes a1 and a2 (first and second emission axes = lens center axis), and The alignment is performed in the optical axis direction so that the emitted light becomes a parallel light beam, and the U-shaped support portions 17a and 17b are filled with an ultraviolet curing adhesive 18 and cured to form collimator lenses 13 and 14. Is fixed.

At this time, as shown in FIG. 4 in particular, by forming two fitting holes 16 at an angle in the main scanning direction, the semiconductor laser array 11 and the collimator lens 1 are formed.
3. Semiconductor laser array 12 and collimator lens 14
By tilting the entire system of
1 and a2 are formed so as to intersect in the vicinity of a polygon mirror (not shown). Thus, on the surface to be scanned, as shown in FIG. 5, the beam spot rows are separated and formed at intervals x in the main scanning direction. You. 5, 11a and 11b indicate beam spots formed by two light emitting points of the semiconductor laser array 11, and 12a and 12b indicate beam spots formed by two light emitting points of the semiconductor laser array 12.

Further, a holder member 19 for holding a support member 15 holding the semiconductor laser arrays 11 and 12 and the collimator lenses 13 and 14 integrally is provided. The holder member 19 has a cylindrical portion 20 at the center on the front side, which is rotatably adjusted to a predetermined support portion around the optical axis C of the scanning optical system as a rotation center, and has a U-shape on the back side. An escape opening 21 for inserting the support portions 17a and 17b and the collimator lenses 13 and 14 is formed, and the support member 15 is fixed by a screw 23 screwed into a screw hole 22. Here, the support member 15 is positioned and fixed to the holder member 19 such that the semiconductor laser arrays 11 and 12 and the collimator lenses 13 and 14 are arranged symmetrically with respect to the optical axis C.

According to such a configuration, each of the semiconductor laser arrays 11 and 12 can be adjusted simply by rotating the holder member 19 about the optical axis C of the scanning optical system and setting the tilt amount γ appropriately. The relative positions of the beam spots 11a, 11b and beam spots 12a, 12b in the sub-scanning direction can be easily and accurately adjusted to a predetermined value. Therefore,
Assembly efficiency is improved.

In the example shown in FIG.
a, 11b row, beam spot 12a, 12b row is 11
The image recording pitches p (= P / 2 = x · cosγ) are arranged in a staggered arrangement in the order of a, 12a, 11b, and 12b. At this time, the sub-scanning pitch p of the shortest spot in the beam spot row is represented by δ = (n−1) P · (1-cosγ), where n is the number of beams, based on the tilt amount γ.
Only change. Assuming that the sub-scanning relative position of the beam spot array is shifted by p as shown in FIG.
The correction by the interval x results in sinγ> p / x. Therefore, in order to make the change amount δ of the sub-scanning pitch of the shortest spot not more than (n−1) P / 8 which does not affect the image quality, the interval x needs to be at least 2p.

A second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is an exploded perspective view showing the multi-beam light source device of the present embodiment, and FIG. 7 is a longitudinal sectional side view in an assembled state. This embodiment is applied to a multi-beam light source device using a beam combining means as in the case of Japanese Patent Application Laid-Open No. 7-72407. Further, it is configured as a four-beam light source device using two semiconductor laser arrays 31, 32 (first and second semiconductor laser arrays) each having two light emitting points. These semiconductor laser arrays 31, 32 have the same structure. In addition, collimator lenses 33 and 34 (first and second collimator lenses) for forming pairs with the semiconductor laser arrays 31 and 32 and coupling the emitted light into parallel light to the scanning optical system are provided. I have.

A first holding member 35 for holding the semiconductor laser array 31 and the collimator lens 33 integrally.
And a second holding member 36 for integrally holding the semiconductor laser array 32 and the collimator lens 34. Each of these holding members 35 and 36 is made of aluminum die-cast, and is formed in the same shape. On the back side of these holding members 35, 36, fitting holes 3 with steps for press-fitting and supporting the semiconductor laser arrays 31, 32 are provided.
7 are formed respectively. Collimator lenses 33, 34
Indicate that a plurality of light emitting points of the semiconductor laser arrays 31 and 32 are arranged in the sub-scanning direction, and that the emission axes a1 and a2
Positioning in the sub-scanning direction is performed so that the two light emitting points are symmetrically arranged with respect to (first and second emission axes = lens center axis), and the emitted light becomes a parallel light beam. The alignment in the optical axis direction is performed, and the respective support members 35 and 36 are aligned.
Is fixed by filling and curing the ultraviolet curing adhesive 39 with respect to the U-shaped support portions 37 and 38 formed in the above. Thus, the first light source unit 4 is formed by the semiconductor laser array 31, the collimator lens 33, and the support member 35.
0, and a second light source section 41 is constituted by the semiconductor laser array 32, the collimator lens 34, and the support member 36.

A parallelogram pillar 42a and a triangular pillar 42 as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-72407.
A beam combining means is provided by a prism 42 in which b is combined. The prism 42 emits a plurality of laser beams emitted from the respective light emitting points of the first and second semiconductor laser arrays 31 and 32 in the sub scanning direction with respect to the optical axis C of the scanning optical system. A half-wave plate 43 is provided at an incident portion from the second semiconductor laser array 32 side. That is, after the light emitted from the second semiconductor laser array 32 is reflected by the oblique side of the parallelogram pillar 42a,
The light is further reflected on the boundary surface with the triangular prism portion 42b, and is emitted from the prism 42 in a state in which the light is transmitted through the triangular prism portion 42 from the first semiconductor laser array 31 side and is close to the sub-scanning direction. .

Further, these first and first units are
A holder member 42 for holding the two light source units 40 and 41 and the prism 42 is provided. Here, the holder member 42 has a cylindrical portion 45 at the center on the front side, which is rotatably adjusted to a predetermined support portion around the optical axis C of the scanning optical system, and has a cylindrical portion 45 on the rear side. The U-shaped support portions 37 and 3 are connected to the prism housing portion 46 in which the prism 42 enters.
Escape openings 47 for inserting the eight portions and the collimator lenses 33 and 34 are formed, and the support members 35 and 36 are fixed by screws 49 screwed into the screw holes 48. At this time, the mounting surfaces 42a and 42b of the holder member 42 to which the first and second support members 35 and 36 are mounted are each angled in the main scanning direction as shown in FIG. Are formed so as to gradually spread toward the surface to be scanned. Therefore, on the surface to be scanned, as shown in FIG. 8, the beam spot rows are separated and formed at intervals x in the main scanning direction. In FIG. 8, 31
Reference numerals a and 31b denote beam spots formed by two light emitting points of the semiconductor laser array 31, and 32a and 32b
Indicates a beam spot formed by two light emitting points of the semiconductor laser array 32.

According to such a configuration, each of the semiconductor laser arrays 31 and 32 can be set simply by adjusting the rotation of the holder member 44 about the optical axis C of the scanning optical system and appropriately setting the tilt amount γ. The relative positions of the beam spots 31a and 31b and the beam spots 32a and 32b in the sub-scanning direction can be easily and accurately adjusted to predetermined values. Therefore,
Assembly efficiency is improved.

In this embodiment, the support members 35,
Each injection shaft a on the mounting surface of the holder member 44 with respect to 36
Cylindrical portions 35a and 36a that can be positioned around the rotation center 1 and a2 are formed, and the rotation thereof can be independently adjusted with respect to the holder member 44 independently. Thereby, the adjacent pitch P in each of the beam spots 31a and 31b and the beam spots 32a and 32b is previously set to P> 2.
By setting the sub-scanning magnification βs of the scanning optical system so as to be p, the inclination amount α about each of the emission axes a1 and a2 as the rotation center is set.
Of the beam spots 31a and 31b and the beam spots 32a and 32b in the sub-scanning direction by adjusting d (=
P / 2 = P · cos α) can be accurately adjusted. Further, each beam spot 31 is also changed depending on the tilt amount γ.
The rows a and 31b and the rows of beam spots 32a and 32b can always be maintained in a constant attitude, and the sub-scanning pitch can be accurately maintained.

As shown in FIG. 9, the four laser beams emitted from the four-beam light source unit 48 having the above-described structure are transmitted through a cylinder lens 49 to a polygon mirror 50.
F, which constitutes the scanning optical system 51 for image formation.
An image is formed on the surface of the photoreceptor 54, which is the surface to be scanned, by the θ lens 52 and the toroidal lens 53, so that four lines are simultaneously recorded. 55 is a reflection mirror. Also, 5
Reference numeral 6 denotes a synchronization detection sensor for receiving laser light reflected by the detection mirror 57 outside the image area to synchronize in the main scanning line direction.

In these embodiments, a configuration example using a semiconductor laser array having two light emitting points has been described. However, a semiconductor laser array having three or more light emitting points is not limited to two light emitting points. It may be used. In short, it is only necessary that a plurality of light emitting points are arranged at the same pitch on the same straight line. Further, regarding the setting of the first and second emission axes a1 and a2, the first and second emission axes a1 and a2 gradually spread toward the surface to be scanned in the second embodiment so as to intersect near the polygon mirror in the first embodiment. I tried to go, but not limited to these,
In short, it is only necessary to be separated by a predetermined angle in the main scanning direction.

[0034]

According to the first aspect of the present invention, each light emission of the first and second semiconductor laser arrays is performed by a simple operation of simply rotating and adjusting the holder member about the optical axis of the scanning optical system. It is possible to adjust the relative position in the sub-scanning between the beam spot arrays by the points, and it is possible to improve the assembly efficiency.

According to the second aspect of the present invention, even in the method using the beam combining means, the simple operation of simply rotating the holder member about the optical axis of the scanning optical system as the rotation center can be performed. It is possible to adjust the relative position in the sub-scanning between the beam spot arrays by the light emitting points of the first and second semiconductor laser arrays, thereby improving the assembling efficiency.

According to the third aspect of the present invention, in the multi-beam light source device according to the second aspect, the sub-scanning pitch in the beam spot arrays of the first and second semiconductor laser arrays is individually adjusted. As a result, higher precision can be achieved, so that higher-quality image recording becomes possible.

According to a fourth aspect of the present invention, in the multi-beam light source device according to the first or second aspect, after adjusting the relative position in the sub-scanning direction between the beam spot rows of the semiconductor laser array, Since the change in the sub-scanning pitch can be suppressed to an allowable value and the accuracy can be improved, high-quality image recording can be performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an optical system showing a relationship between a light emitting point pitch Ps of a semiconductor laser array having two light emitting points and a sub-scanning pitch Ps ′ on a surface to be scanned, as a premise of the present invention.

FIG. 2 is an explanatory diagram showing a method of arranging a plurality of light emitting points.

FIG. 3 is an exploded perspective view showing the multi-beam light source device according to the first embodiment of the present invention.

FIG. 4 is a vertical sectional side view in the assembled state.

FIG. 5 is an explanatory diagram showing a beam spot array on a surface to be scanned.

FIG. 6 is an exploded perspective view showing a multi-beam light source device according to a second embodiment of the present invention.

FIG. 7 is a vertical sectional side view in the assembled state.

FIG. 8 is an explanatory diagram showing a beam spot array on a scanned surface.

FIG. 9 is a perspective view illustrating a configuration example of a laser printer.

[Explanation of symbols]

 Reference Signs List 11 first semiconductor laser array 12 second semiconductor laser array 13 first collimator lens 14 second collimator lens 15 support member 19 holder member 31 first semiconductor laser array 32 second semiconductor laser array 33 first Collimator lens 34 Second collimator lens 35 First support member 36 Second support member 40 First light source unit 41 Second light source unit 42 Beam combining unit 44 Holder member

Claims (4)

[Claims] 1. A first semiconductor laser array having a plurality of light emitting points on a straight line, a second semiconductor laser array having the same structure as the first semiconductor laser, and an emission from the first semiconductor laser array. A first collimator lens for coupling the laser light to be emitted, a second collimator lens for coupling the laser light emitted from the second semiconductor laser array, the first semiconductor laser array and the first And the second semiconductor laser array and the second coupling lens are separated by a predetermined angle in the main scanning direction with respect to the first emission axis. A support member arranged on a second emission axis to hold these members integrally, and scanning a plurality of laser beams emitted from the first and second semiconductor laser arrays And a holder member that is rotatably adjusted about the optical axis of a scanning optical system for forming a beam spot on the surface to be scanned and that holds the support member. 2. A first semiconductor laser array having a plurality of light emitting points on a straight line, a second semiconductor laser array having the same structure as the first semiconductor laser, and emission from the first semiconductor laser array. A first collimator lens for coupling the laser light to be emitted, a second collimator lens for coupling the laser light emitted from the second semiconductor laser array, the first semiconductor laser array and the first A first support member for forming a first light source section by disposing the coupling lens on a first emission axis and integrally holding the coupling lens, and the second semiconductor laser array and the second coupling A second support member that forms a second light source by holding a lens and a lens on a second emission axis and integrally holding the lens, and a plurality of laser beams emitted from the first and second semiconductor laser arrays; A beam combining unit that emits the plurality of laser beams in the sub-scanning direction in proximity to an optical axis of a scanning optical system for scanning light to form a beam spot on a surface to be scanned; The first support member and the first support member are provided so as to be freely rotatable about the optical axis of the first support member at a predetermined angle with respect to the main scanning direction. A multi-beam light source device comprising: a second support member; and a holder member that integrally holds the beam combining unit. 3. The holder according to claim 2, wherein the first and second support members are rotatably adjustable about the corresponding first and second injection axes, respectively, on the holder member. Multi-beam light source device. 4. A plurality of light-emitting points in the first and second semiconductor laser arrays are arranged in the sub-scanning direction, and the first and second emission axis intervals on the surface to be scanned are adjacent to each other. 3. The multi-beam light source device according to claim 1, wherein the multi-beam light source device is set to be at least twice the recording line pitch.