JPH06281871A - Multibeam light source device and optical scanning device using the same - Google Patents

Abstract

PURPOSE:To prevent optical cross talk and to properly form a scanning beam. CONSTITUTION:In a multibeam light source device 10 bisecting a beam from the plural light emitting sources of a semiconductor laser array 12 by means of an optical path splitting means 20 and controlling the output of the semiconductor laser array 12 in accordance with the light, quantities made incident on the respective light receiving elements 16, 17 of a light receiving element array 13, an aperture 22 or a mirror 23 whose reflection angle is changeable is provided on the incident optical path led to the light receiving element array 13, a supporting body 19 holding the semiconductor laser array 12 and a substrate 11 holding the light receiving element array 13 are coupled so as to be relatively and freely displaced or a light converging means 21 splitting/ converging the bisected beam into a long elliptical shape in the perpendicular direction to the arrangement direction of the light emitting source is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-beam light source device and an optical scanning device using the same.

[0002]

2. Description of the Related Art An image forming apparatus such as a laser printer which combines electrophotographic technology and laser scanning technology can use plain paper and can obtain high quality images at high speed. It is rapidly spreading as a digital copying machine. A general laser printer forms an electrostatic latent image on a photoconductor by a laser scanning optical system using a rotating polygon mirror, develops it with toner, and then transfers and fixes it on recording paper to obtain an output image. ing.

FIG. 37 shows an example of a general laser scanning device. The laser beam emitted from the semiconductor laser 1 modulated according to the image signal is collimated by the collimator lens 2 and reflected by the rotating rotary polygon mirror 3, and is focused on the photoconductor 5 by the imaging lens 4 (fθ lens). An image is formed on the surface of the photoconductor 5 as a minute spot, thereby forming an electrostatic latent image on the surface of the photoconductor 5. The light receiving element 6 provided outside the image area on the scanning start side on the scanning line is for controlling the image writing start position in the main scanning direction.

In such a laser printer, in order to realize an optical system that outputs 100 A4 size images per minute, the speed of the photoconductor 5 is 500 mm / s.
The rotation number R (rpm) of the rotary polygon mirror 3 in the case of a single beam is given by the following equation.

R = Vo × DPI × 60 / (25.4 × N) (1) where Vo is the speed of the photoconductor 5 (mm / sec), DP
I is the number of dots recorded per inch, and is generally 3
00 to 400, N is the number of reflecting surfaces of the rotary polygon mirror 3, and is generally 5 to 10. Vo = 500, DPI = 300,
Substituting N = 6 into the equation (1), the rotational speed R of the rotary polygon mirror 3
Is also 59055 (rpm). At such a rotation speed, the use of a conventional ball bearing as a bearing for supporting the rotating shaft has an influence on durability, and therefore a special bearing such as a fluid bearing or a magnetic bearing is required, resulting in an increase in cost. In addition, since the modulation frequency of the semiconductor laser, which is the light source, is increased, it is necessary to increase the data transfer rate from the laser control circuit and the host machine, which increases the cost.

As a method for increasing the speed, there is a method of collectively scanning a plurality of laser beams. In this case, assuming that the number of laser beams is M, the number of revolutions R of the rotary polygon mirror 3 and the modulation frequency of the laser can be set to 1 / M, which makes it possible to use an inexpensive bearing, It is not necessary to particularly increase the transfer speed of, and it is possible to significantly reduce the cost.

In order to increase the printing speed by using a plurality of laser beams in this way, there is a beam combining method in which the laser beams from a plurality of semiconductor lasers are brought close to each other by a combining means such as a prism or a mirror. There is also a method of using as a light source a semiconductor laser array in which a plurality of light emitting sources are arranged in an array.

In the former beam synthesizing method, since the structure of the laser beam synthesizing means is complicated, the size of the device is easily increased, and even if the relative position between the semiconductor lasers is slightly changed due to temperature fluctuation, vibration, etc. The relative position of the laser beam on the body changes greatly due to the action of the optical lever, which makes stable optical scanning difficult.

The latter method using the semiconductor laser array does not have the above-mentioned inconvenience because a plurality of light emitting sources are provided in the same chip in proximity to each other. However, it is difficult to constantly maintain a stable light amount (light emission output) due to variations in characteristics of individual light emitting sources and differences in characteristics due to changes over time.

Therefore, as a device disclosed in Japanese Utility Model Laid-Open No. 63-89273, as shown in FIG. 38, a semiconductor laser in which a plurality of light emitting elements (laser diodes) 7a, 7b, 7c are arranged in an array form. A waveguide member (light guide) 9 is provided between the array 7 and the light receiving element array 8 in which a plurality of light receiving elements 8a, 8b, 8c are arranged in an array, and the front light FBa is emitted from the light emitting elements 7a, 7b, 7c. , FBb, F
Bc is irradiated toward the photoconductor to emit light from the light emitting elements 7a, 7b, 7
The backward light BBa, BBb, BBc of c is incident on the light receiving elements 8a, 8b, 8c by the waveguide member 9, and the individual light receiving elements 8a
a, 8b, 8c light emitting elements 7a, 7b, 7 according to the amount of received light
There is a method of controlling the output of c.

Further, regarding output control when a semiconductor laser array is used as a light source of a laser scanning optical system, Japanese Patent Application Laid-Open No. 59-19252 and Japanese Patent Application Laid-Open No. 1-10 are disclosed.
There is a method disclosed in Japanese Patent No. 6486. This method
Each semiconductor laser of the semiconductor laser array is turned on one by one in a time-series manner during each invalid scan period until the next scan for each line scan, and the back beam light amount detector (monitor PD) built in the semiconductor laser array package is turned on. ) Is used to detect the light amount, and the output of each semiconductor laser is controlled by the output signal of the back beam light amount detector.

Further, as a prior art, which is not a publicly known example, there is a proposal (Japanese Patent Application No. 4-124699) filed by the present applicant on May 18, 1992. This is because a part of the front light of each light emitting element of the semiconductor laser array is divided and is independently guided to each light receiving element of the light receiving element array by a condensing means such as a lens, and the amount of light received by each light receiving element is changed. To control the output of the corresponding light emitting element. According to this, the monitor mechanism may be configured outside the package of the semiconductor laser array by dividing and monitoring a part of the forward light of the semiconductor laser array, and thus, there is no restriction on the arrangement space of the components. Also, it becomes possible to always obtain the monitor output independently. Therefore, real-time output control with high accuracy becomes possible.

[0013]

Problem to be Solved by the Invention Shown in FIG.
According to the invention described in Japanese Patent Publication No. 3-89273, when the rear lights BBa, BBb, BBc of the light emitting elements 7a, 7b, 7c are independently received in a narrow space in the package, the light emitting elements 7a, 7b, 7c are not detected. Since the divergence angle of the laser light emitted by is as large as about 10 to 40 °, it is difficult to completely separate these laser lights, and an optical crosstalk phenomenon occurs. In addition, even if they are separated, the light emitting element 7
a, 7b, 7c, the light receiving elements 8a, 8b, 8c, and the waveguide member 9 are extremely strict in relative positioning,
The waveguide member 9 causes a problem that the amount of light guided to the light receiving elements 8a, 8b, 8c decreases.

Further, the methods disclosed in JP-A-59-19252 and JP-A-1-106486 use a common light-receiving element and perform main scanning every period during which there is no information signal (outside the effective scanning period). In the above, the light emitting elements are modulated one by one to control the output, but at least the output can be controlled for each scanning, and it is impossible to cope with the output fluctuation having a smaller time constant. For example, in the semiconductor laser array, the light emitting elements are arranged close to each other in the same chip as described above, and thermal interference occurs between the light emitting elements due to temperature fluctuations caused by turning on and off of the other light emitting elements, thereby causing light emission. The output of the element fluctuates. When the distance between the light emitting elements is set to 50 to 100 μm, the time constant of the output fluctuation due to the thermal interference of the semiconductor laser array is shown to be a value of several 100 μs to several ms as an experimental value.

Furthermore, the above-mentioned prior art (Japanese Patent Application No. 4-1).
No. 24699) can solve some of the problems of the methods disclosed in JP-A-59-19252 and JP-A-1-106486, but leaves the following problems.

First, since the optical path length between the semiconductor laser array and the light receiving element array, which are optically conjugate with each other by the light converging means, rapidly increases due to an increase in the imaging magnification, the light source device is In order to reduce the size, it is necessary to set the imaging magnification as small as possible. On the other hand, the distance between the light emitting elements of the semiconductor laser array is enlarged or reduced according to the imaging magnification on the light receiving element array.
If the imaging magnification is small, optical crosstalk occurs unless the relative positional accuracy between the incident laser beam and the light-receiving element array, particularly the positional accuracy in the array direction of the light-receiving elements, is strict.

FIG. 39 (a) schematically shows the relationship between the position shift of the light receiving elements in the array of the light receiving elements in the array direction and the optical crosstalk. The broken line indicates that the image forming magnification is higher. The solid line is the optical crosstalk at lower magnification.
This optical crosstalk is noise in which leak light from a laser beam that should be incident on only one light receiving element is incident on the other light receiving element. FIG. 39B is a schematic diagram showing a correspondence relationship between the light emitting elements LD1 and LD2 of the semiconductor laser array and the light receiving elements PD1 and PD2 of the light receiving element array.

In FIGS. 39 (a) and 39 (b), the noise due to the leaked light is, for example, A ₁ (A ₁ ') = I ₂₁ / I ₁₁ A ₂ (A ₂ ') = I ₁₂ / I ₂₂ Shown. C ₀ is the allowable value of optical crosstalk,
B and B ′ are permissible ranges of positional displacement of the light receiving elements PD1 and PD2 with respect to C _{0 at the} respective imaging magnifications, B is a high magnification and B ′ is a low magnification. As described above, as the imaging magnification decreases, the allowable range of positional deviation on the light receiving element array becomes narrower. Further, since the laser beam is narrowed down to a minute spot on the light-receiving element array according to the imaging magnification, the energy density sharply increases on the light-receiving surface as the imaging magnification decreases, which causes saturation of photoelectric conversion. This causes deterioration of the response characteristics of the light receiving element, which impairs high speed output control.

In FIG. 40, the cutoff frequency when the frequency response of the light receiving element is measured by changing the laser beam under the same light amount conditions with the cutoff frequency of the laser beam as the vertical axis and the beam spot diameter as the horizontal axis. It is a plot of the change in the frequency at which the gain is -3 dB when the gain is DC. According to this, it can be seen that the cutoff frequency sharply decreases as the beam spot diameter decreases.

Further, when the imaging magnification m is set to 1 or more, if the coupling magnification of the condensing means is increased while keeping the optical path length between the semiconductor laser array and the light receiving element array constant, the magnification increases. As a result, the distance between the semiconductor laser array and the condensing means is shortened, and the semiconductor laser array, the optical path separating means, the condensing means, etc. are arranged close to each other, and the interference of these parts causes the miniaturization of the device. Has become one of the factors that hinders.

Further, in the optical scanning device shown in FIG. 37, a method of setting the scanning line pitch on the photoconductor 5 by rotating the semiconductor laser 1 around the optical axis is generally used, but the scanning optical system is used. As a means for shaping the incident light beam diameter on the beam, a method using a prism P as shown in FIG. 41 and a beam compressor in which cylinder lenses R1 and R2 are arranged confocal only in one direction as shown in FIG. There is a method to use.

The method of using the prism P is to convert the light beam diameter according to the relationship of D ₀ / D _i = cos θ ₀ / cos θ _i in FIG. 41. However, since the optical axis is bent, it will be in the optical path. Each optical system must be arranged three-dimensionally, and there is a problem that the device becomes large.

The method using the beam compressor is shown in FIG.
2, the light beam diameter is converted by the ratio of the focal lengths of the cylinder lenses R1 and R2 due to the relationship of D ₀ / D _i = f ₂ / f ₁ , but a plurality of cylinder lenses R1 and R2 are required. Therefore, the number of mounting members and fastening members such as screws for holding the cylinder lenses R1 and R2 increases, and further, due to the accumulation of eccentricity errors of the individual components, the optical axis shifts or the beam spot tilts. Therefore, there is a problem in that the placement accuracy of each component becomes strict.

[0024]

The invention according to claim 1 is
A semiconductor laser array having a plurality of light emitting sources, an optical path separating means for dividing a beam from the light emitting sources into two, a condensing means for converging the beams divided by the optical path separating means, and a plurality of light emitting sources corresponding to the light emitting sources. A multi-beam light source device for controlling the output of the semiconductor laser array according to the amount of light input to the light receiving element array. In, an aperture is provided in the optical path from the semiconductor laser array to the light receiving element array.

According to a second aspect of the present invention, there is provided a semiconductor laser array having a plurality of light emitting sources, an optical path separating means for dividing the beam from the light emitting sources into two, and a focusing means for converging the beams divided by the optical path separating means. The semiconductor device comprises a light means and a light-receiving element array having a plurality of light-receiving elements corresponding to the light-emitting source and arranged at a focal point position of the light-collecting means, and the semiconductor depending on an amount of light input to the light-receiving element array. In the multi-beam light source device that controls the output of the laser array,
A mirror whose reflection angle is changed by the optical axis changing means is provided in the optical path from the semiconductor laser array to the light receiving element array.

According to a third aspect of the present invention, a semiconductor laser array having a plurality of light emitting sources, an optical path separating means for dividing the beam from the light emitting sources into two, and a focusing means for converging the beams divided by the optical path separating means. The semiconductor device comprises a light means and a light-receiving element array having a plurality of light-receiving elements corresponding to the light-emitting source and arranged at a focal point position of the light-collecting means, and the semiconductor depending on an amount of light input to the light-receiving element array. In the multi-beam light source device that controls the output of the laser array,
A support body holding the semiconductor laser array and a substrate having at least a part of an output control circuit for driving the semiconductor laser array and the light receiving element array are provided, and the light receiving surface of the light receiving element array is the support body. The support and the substrate are brought into contact with each other to be relatively displaceably coupled in the arrangement direction of the light emitting sources.

According to a fourth aspect of the present invention, there is provided a semiconductor laser array having a plurality of light emitting sources, an optical path separating means for dividing a beam from the light emitting sources into two, and a focusing means for converging the beams divided by the optical path separating means. The semiconductor device comprises a light means and a light-receiving element array having a plurality of light-receiving elements corresponding to the light-emitting source and arranged at a focal point position of the light-collecting means, and the semiconductor depending on an amount of light input to the light-receiving element array. In the multi-beam light source device that controls the output of the laser array,
A concave groove located on the dividing line of the light receiving element was formed in the protective cover of the light receiving element array.

According to a fifth aspect of the present invention, a semiconductor laser array having a plurality of light emitting sources, an optical path separating means for dividing a plurality of laser beams from the light emitting sources into two, and a plurality of optical path separating means are provided. Condensing means for separating and condensing the laser beam into an elliptical shape that is long in a direction orthogonal to the direction in which the light emitting sources are arranged, and a plurality of light receiving elements corresponding to the light emitting sources are arranged in the arranging direction of the light emitting sources. And a light receiving element array arranged in parallel.

According to a sixth aspect of the invention, in the fifth aspect of the invention, a single-lens anamorphic lens is used as the light converging means, and a light-receiving element array is provided in the vicinity of the image plane of the anamorphic lens in the arrangement direction of the light sources. I placed it.

According to a seventh aspect of the invention, in the fifth aspect of the invention, the condensing means is formed by a spherical or aspherical lens rotationally symmetric with respect to the optical axis and a cylinder lens.

According to an eighth aspect of the invention, in the fifth aspect of the invention, a condensing means is formed by a rotationally symmetric spherical or aspherical lens and a mirror for condensing or diverging the laser beam. The light receiving element array is formed integrally with the mirror for folding the optical path or the optical path separating means, and the light receiving element array is arranged in the vicinity of the image plane of the light collecting means in the arrangement direction of the light emitting sources.

The invention according to claim 9 is the invention according to claim 5, 6, or 7.
Alternatively, in the invention described in Item 8, a slit is provided in the vicinity of the image forming surface of the light collecting means in the direction orthogonal to the arrangement direction of the light emitting sources of the semiconductor laser array.

According to a tenth aspect of the present invention, at least a semiconductor laser array having a plurality of light emitting sources, an optical path separating means for dividing a beam from the light emitting sources into two, and a beam divided by the optical path separating means are focused. A multi-beam light source device comprising a light-collecting element array for controlling the output of the semiconductor laser array according to the amount of light input having a plurality of light-receiving elements corresponding to the light-emitting source A perfect circular aperture and a pair of cylinder lenses having a curvature only in the direction orthogonal to the scanning direction are provided between the deflector and the collimator lens for collimating the other beams split by the means.

According to an eleventh aspect of the present invention, in the tenth aspect of the invention, the cylinder lens located on the semiconductor laser array side is supported rotatably about the optical axis.

[0035]

According to the first aspect of the invention, even if the divergence angle of the laser beam emitted from the light emitting source of the semiconductor laser array varies, the beam diameter imaged on the light receiving element array is made uniform by the aperture. be able to. Therefore, stable performances such as optical crosstalk and frequency response can be obtained.

According to a second aspect of the present invention, the direction of the folding mirror that reflects the laser beam emitted from the semiconductor laser array to the light receiving element array is changed by the optical axis changing means, thereby changing the mounting position of the light collecting means. An optical axis shift caused by an error or radiation surface accuracy can be corrected by a mirror. As a result, optical crosstalk can be suppressed to a minimum, and a margin for optical axis shift over time and decentering of the optical element can be secured.

It is needless to say that the invention according to claim 3 can stabilize the output control of the semiconductor laser array by reducing the disturbance factor by providing the light receiving element array on the substrate on which the output control circuit is formed. However, the optical path length between the semiconductor laser array and the light receiving element array can be accurately determined by bringing the light receiving surface of the light receiving element array into contact with the support holding the semiconductor laser array. Further, since the substrate and the support can be relatively displaced along the arrangement direction of the light emitting sources, the center of the beam spot can be aligned with a desired position of the light receiving element array.

According to the fourth aspect of the present invention, the margin of optical crosstalk can be increased by the groove formed in the protective cover of the light receiving element array.

According to a fifth aspect of the present invention, a part of the plurality of laser beams from the semiconductor laser array is separated as output control light by the optical path separating means, and the light condensing means is long in the direction orthogonal to the arrangement direction of the light emitting sources. The laser beam can be separated and condensed into an elliptical laser beam and guided to each light receiving element of the light receiving element array, which reduces the energy density of the light receiving beam while maintaining good optical crosstalk. You can Therefore, it is possible to maintain good frequency response without increasing the imaging magnification so much, which enables miniaturization and high-speed and highly accurate output control.

According to a sixth aspect of the present invention, a single anamorphic lens is used to form an image of a plurality of laser beams from the semiconductor lens array as independent elliptical beams on each light receiving element of the light receiving element array. Therefore, the optical system can be simplified and the cost can be reduced, and the space for arranging the optical components can be small, so that the miniaturization can be promoted.

Since the anamorphic optical system is constituted by the spherical or aspherical lens and the cylinder lens, the number of parts of the anamorphic optical system can be reduced and the structure can be simplified without using a special lens. Can be converted.

According to the eighth aspect of the present invention, since the optical path separating means or the folding mirror can be made to perform the lens function of the condensing system, the number of parts of the anamorphic optical system can be reduced and the structure can be simplified. You can

According to the ninth aspect of the invention, flare light can be effectively removed without blocking the effective light by the slit, and the optical crosstalk can be reduced.

According to a tenth aspect of the present invention, when the laser beam from the semiconductor laser array is scanned on the surface to be scanned by the deflector, an optical system of a simple combination of an aperture and a cylinder lens is provided to provide an optical axis. When the multi-beam light source device is rotated around the optical axis, the laser beam can be shaped by the pair of cylinder lenses in the sub-scanning direction without changing the beam diameter in the main scanning direction.

In the eleventh aspect of the present invention, among the pair of cylinder lenses, the interval between the scanning lines can be adjusted by rotating the cylinder lens on the multi-beam light source device side around the optical axis. It is possible to easily replace the multi-beam light source device and improve maintainability.

[0046]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. First, FIG. 1 shows the configuration of the multi-beam light source device 10. The semiconductor laser array 1 is provided on the substrate 11.
An output control circuit (which will be described later) that drives 2 is formed, and a light receiving element array 13 connected to the output control circuit is held. As shown in FIGS. 9 and 10, the semiconductor laser array 12 includes a plurality of light emission sources 14 and 15.
And the light-receiving element array 12 has these light-emitting sources 14, 1
A plurality of light receiving elements 1 arranged in the same direction as the arrangement direction of 5
6 and 17.

As shown in FIG. 1, the semiconductor laser array 12 and the light receiving element array 13 are mounted on a support 19 having a plurality of columnar mounting portions 18 which are joined to the substrate 11.
A half mirror 20 as an optical path separating unit that divides the laser beam from the semiconductor laser array 12 into two, an anamorphic lens 21 as a condensing unit, an aperture 22, and a folding mirror 23 are held.
In addition, as shown in FIGS. 1 and 3, the support 19 has a fulcrum portion 24 that holds the mirror 23 swingably and a mirror 23.
There are provided leaf springs 25 and 26 that support the plate spring 25, and an adjusting screw 27 that is screwed into a tap hole formed in the leaf spring 25 to change the tilt angle of the mirror 23.
Further, as shown in FIG. 1, a lens case 28 fixed to the support 19 holds a collimator lens 29 and an aperture 30 for collimating the laser beam transmitted through the half mirror 20. As shown in FIG. 2, the aperture 31 of the aperture 30 is a perfect circle, and the diameter of the aperture is smaller than the luminous flux of the laser beam from the light emitting sources 14 and 15 of the semiconductor laser array 12. In FIG. 2, the laser beams transmitted through the half mirror 20 are indicated by the symbols b ₁ and b ₂ .

Next, the structure of the support 19 and the mounting structure of the support 19 and the substrate 11 will be described. As shown in FIG. 4, the substrate 11 has a plurality of mounting holes 33 through which the screws 32 screwed into the mounting portions 18 of the support body 19 are inserted, guide holes 34 located on both sides of the light receiving element array 13, and semiconductors. A connection portion 35 to which the laser array 12 is connected is formed. The mounting hole 33 and the guide hole 34 are defined in an oval shape that is long along the arrangement direction of the light emitting sources 14 and 15 and the light receiving elements 16 and 17. Further, the support 19 has a holding portion 36 for holding the half mirror 20, and the anamorphic lens 2
A holding portion 37 that holds the 1 and the aperture 22 in a bound state, and a holding portion 38 that holds the mirror 23 are formed. The half mirror 20, the anamorphic lens 21, and the aperture 22 are prevented from moving upward by a leaf spring 26 that presses the mirror 23.

FIG. 5 shows a state where the substrate 11 and the support body 19 are viewed from the back side. The support body 19 has a cylindrical holding portion 39 for holding the semiconductor laser array 12, and the light receiving element array 13 receives light. A positioning portion 40 that contacts the surface and a cylindrical projection 41 that is guided by the guide hole 34 of the substrate 11 are formed.

A semiconductor laser array 1 is provided on the substrate 11.
2 and an LD control circuit (which will be described later) that controls the output thereof are connected to each other. Therefore, it is not necessary to transmit a weak signal of several 100 μA to several mA from the light receiving element 16 or 17 through an electric wire or the like, and the signal can be transmitted without being affected by noise.

As shown in FIG. 6, the light emission level command signal is input to the comparison amplifier 42 and the current converter 43, and a part of the output of the light emission source 14 or 15 is monitored by the light receiving element 16 or 17. The comparison amplifier 42, the light emitting source 14 or 15 and the light receiving element 16 or 17 form an optical / electrical negative feedback loop, and the comparison amplifier 42 induces in the light receiving element 16 or 17 in proportion to the output of the light emitting source 14 or 15. The received light signal proportional to the generated photocurrent is compared with the light emission level command signal, and according to the result, the forward current of the light emission source 14 or 15 is controlled so that the light received signal and the light emission level command signal become equal. To do. Further, the current converter 43 outputs a current preset according to the light emission level signal so that the light reception signal and the light emission level command signal become equal to each other. This current is the light output / forward current characteristic of the light emitting source 14 or 15 and the light receiving element 1.
The current is preset based on the coupling coefficient between 6 or 17 and the light emitting source 14 or 15, and the light input / light receiving signal characteristics of the light receiving element 16 or 17. As shown in FIG. 7, output control circuits 44 and 45 for driving the semiconductor laser array 12 are formed on the substrate 11 for each of the light emission sources 14 and 15.

When the crossover frequency in the open loop of the optical / electrical negative feedback loop is f ₀ and the DC gain is 10000, the step response of the output Pout of the semiconductor laser array 12 should be approximated as follows. You can

Pout = PL + (PS−PL) exp (−2πf ₀ t) PL: Optical output at t = ∞ PS: Light quantity set by current converter 43 Optical / electrical negative feedback loop DC gain in open loop 100
Therefore, PL is considered to be equal to the set light amount when the allowable range of the setting error is 0.1% or less. Therefore, if the light quantity PS set by the current converter 43 is equal to PL, the semiconductor laser array 12
Instantly becomes equal to PL. Even if PS varies by 5% due to a disturbance factor or the like, if f ₀ = 40 MHz or so, the error of the optical output of the semiconductor laser array 12 with respect to the set value is 0.4% or less after 10 ns.

The operation of the multi-beam light source device 10 having such a structure will be described with reference to FIG. The laser beam emitted from each of the light emission sources 14 and 15 of the semiconductor laser array 12 is split by the half mirror 20. The laser beam transmitted through the half mirror 20 is collimated by the collimator lens 29, and the beam diameter is determined by the aperture 30 to be emitted. The laser beam reflected by the half mirror 20 is condensed by the anamorphic lens 21 and is focused on each of the light receiving elements 16 and 17 of the light receiving element array 13 via the aperture 22 and the mirror 23. Here, as shown in FIGS. 9 and 10, the light emitting sources 14 and 15 and the light receiving elements 16 and 17 are linked by an anamorphic lens 21 in an optical conjugate relationship at least in the arrangement direction of the light emitting sources 14 and 15. There is. Then, the pitch p of the light emitting sources 14 and 15 is enlarged with a predetermined imaging magnification m, and an image is formed on the light receiving elements 16 and 17 of the light receiving element array 13 with a pitch of p ′. The output from the semiconductor laser array 12 is output by the output control circuits 44 and 45 on the substrate 11 in accordance with the amount of light detected by the light receiving elements 16 and 17.
Controlled by.

In FIG. 8, assuming that 12A is the object plane (arrangement surface of the semiconductor laser array 12) and 13A is the image plane (arrangement surface of the light receiving element array 13), from the semiconductor laser array 12 to the light receiving element array 13. By providing the aperture 22 in the optical path, even if the divergence angle of the laser beams emitted from the light emitting sources 14 and 15 of the semiconductor laser array 12 varies, the diameter of the beam focused on the light receiving element array 13 can be adjusted. 22 to make it uniform. Therefore, stable performances such as optical crosstalk and frequency response can be obtained. In addition, the light source 14,
By disposing the aperture 22 near the image-side focus F ′ of the anamorphic lens 21 in the array direction of 15, the light emitting sources 14 and 15 are misaligned with the optical axis of the anamorphic lens 21, and the light emitting source with respect to the optical axis of the anamorphic lens 21. Even if there is a difference in array position between 14 and 15, the irradiation position of the laser beam on the aperture 22 is unlikely to change, and the amount of light reaching the light-receiving element array 13 and the beam diameter can be made more uniform. This is a specific configuration and action corresponding to the invention of claim 1.

Further, by changing the direction of the mirror 23 for reflecting the laser beam emitted from the semiconductor laser array 12 to the light receiving element array 13 with the adjusting screw 27, an error in the mounting position of the optical system and an optical axis shift can be prevented. Can be corrected by. As a result, the center of division of the half mirror 20 and the center of the beam spot can be aligned, optical crosstalk can be suppressed to a minimum, and a margin for optical axis shift over time and eccentricity of the optical element can be secured. This is a specific configuration and action corresponding to the invention of claim 2.

Further, it is needless to say that by providing the light receiving element array 13 on the substrate 11 on which the output control circuits 44 and 45 are formed, it is possible to reduce disturbance factors and stabilize the output control of the semiconductor laser array 12. However, the light receiving surface of the light receiving element array 13 is brought into contact with the positioning portion 40 (see FIG. 5) formed on the support 19 that holds the semiconductor laser array 12, so that the semiconductor laser array 12 and the light receiving element array 13 are separated from each other. The optical path length between the two can be accurately determined. Further, since the substrate 11 and the support 19 can be relatively displaced along the arrangement direction of the light emitting sources 14 and 15, the center of the beam spot can be aligned with a desired position of the light receiving element array 13. This is a specific configuration and action corresponding to the invention of claim 3.

Further, as shown in FIG. 12, the protective cover 48 of the light-receiving element array 13 is formed with a concave groove 49 located on the dividing line of the light-receiving elements 16 and 17, whereby
The groove 49 can increase the margin of optical crosstalk. This is a specific configuration and action corresponding to the invention of claim 4.

Here, as shown in FIG. 10, the anamorphic lens 21 is set so that the focal lengths of the arrangement directions of the light emitting sources 14 and 15 and the direction orthogonal to the arrangement direction (orthogonal arrangement direction) are different, Since the light-receiving element array 13 is arranged at a position where light is collected and imaged in the array direction and not imaged in the array orthogonal direction, the laser beams emitted from the light emitting sources 14 and 15 are arranged in the orthogonal direction. Then, the laser beams are separated into long and thin elliptic (linear) laser beams and are incident on the light receiving element array 13. Therefore, the individual laser beams can be satisfactorily separated and guided to the corresponding light-receiving elements 16 and 17, and a laser beam having a non-imaging spread in the direction orthogonal to the array can be obtained, which results in good optical crosstalk. It is possible to reduce the energy density of the laser beam on the light receiving surface while maintaining the above. Therefore, the light receiving element 16, without increasing the imaging magnification to increase the beam diameter,
Since the response of No. 17 can be maintained, the device can be downsized, and high-speed and highly accurate output control can be performed. This is a specific configuration and action corresponding to claim 5.

Two or more light emitting sources 14 and 15 may be arranged. In this case, the light receiving element array 13 including the light receiving elements 16 and 17 corresponding to the number of the light emitting sources 14 and 15 is provided.
To use.

Next, a second embodiment of the present invention will be described with reference to FIGS. 13 to 15. This embodiment is one of the embodiments of the condensing means for condensing the laser beam separated by the half mirror 20, and has a specific configuration and action corresponding to the invention of claim 6. The same parts as those in the above-described embodiment are designated by the same reference numerals and the description thereof is omitted (the same applies hereinafter). First,
As shown in FIG. 13, a case where an anamorphic lens 21 having a simple thin lens is used as a light converging means will be considered. FIG. 6A shows an optical path when the focal length of the anamorphic lens 21 in the arrangement direction of the light emitting sources 14 and 15 is f, and FIG. 8B shows a direction orthogonal to the arrangement direction of the light emitting sources 14 and 15 (orthogonal arrangement). Direction), where the focal length of the anamorphic lens 21 is f '(f'> f), the figure (c) shows the focal length of the anamorphic lens 21 in the array orthogonal direction as f '(f'<f). It is the optical path when. The optical path length between the object plane 12A (arrangement surface of the semiconductor laser array 12) and the anamorphic lens 21 is s (s> 0), and between the anamorphic lens 21 and the image plane 13A (arrangement surface of the light-receiving element array 13). Assuming that the optical path length is s ′ (s ′> 0) and the imaging magnification of the light emitting sources 14 and 15 in the arrangement direction is m (m> 0), the light emitting sources 14 and 15
In order to form the laser beam on the image surface 13A only in the arrangement direction of, the following setting is made: s = (1 + 1 / m) · fs ′ = m · s = (1 + m) · f f ≠ f ′ Of course, the optical path length L from the object plane 12A to the image plane 13A at this time is L = s + s ′ = (m + 1 / m + 2) · f.

Next, another concrete example of the light collecting means is shown in FIG. 9A shows an optical path in the arrangement direction of the light emitting sources 14 and 15, and FIG. 9B shows an optical path in a direction orthogonal to the arrangement direction of the light emitting sources 14 and 15 (orthogonal arrangement direction). A design example of the single-lens anamorphic lens 21 in the present embodiment is shown. The anamorphic lens 21 is made of glass or a polymer resin such as polycarbonate or polymethylmethacrylate. The focal lengths f and f ′, the imaging magnification m, and the total optical path length L are the same as those in the above specific example.
f = 5 mm, f ′ = 4.6 mm, m = 5, L = 36.5
mm. Refractive index n is 1.5, and other set values are: Object surface 12A to first surface of anamorphic lens 21 d ₀ = 5 mm Thickness of anamorphic lens 21 d ₁ = 1.5 mm Second surface of anamorphic lens 21 Distance of image plane 13A d ₂ = 30 mm Radius of curvature of the first surface of the anamorphic lens 21 in the arrangement direction of the light sources 14 and 15 r _1x = ∞ Direction orthogonal to the arrangement direction of the light sources 14 and 15 (array orthogonal direction) Radius of curvature r _1y = ∞ of the first surface of the anamorphic lens 21 in the arranging direction of the second surface of the anamorphic lens 21 r _2x = −2.5 mm The radius of curvature r _2y of the second surface of the anamorphic lens 21 in the orthogonal direction (orthogonal direction of the array) is −2.3 mm.

In design example 2, in FIG. 15, f = 5 m
m, f '= 5.46 mm, m = 5, L = 36.5 mm,
The refractive index n is set to 1.5, and the other set values are: the distance d ₀ = 5 mm from the object surface 12A to the first surface of the anamorphic lens 21 the wall thickness d ₁ = 1.5 mm of the anamorphic lens 21 of the anamorphic lens 21. Distance d ₂ = 30 mm from the second surface to the image surface 13A Radius of curvature of the first surface of the anamorphic lens 21 in the array direction of the light sources 14 and 15 r _1x = ∞ Direction orthogonal to the array direction of the light sources 14 and 15 (array The radius of curvature r _1y = ∞ of the first surface of the anamorphic lens 21 in the (orthogonal direction) r _2x = −2.5 mm of the radius of curvature of the second surface of the anamorphic lens 21 in the arrangement direction of the light sources 14 and 15 is set in a direction (arranged perpendicular direction) perpendicular to the arrangement direction as described above curvature radius r _2y = -2.73mm of the second surface of the anamorphic lens 21 .

In such a structure, in design example 1 shown in FIG. 14, since f '<f is set, as shown in FIG. 14B, a direction (or direction) orthogonal to the arrangement direction of the light emitting sources 14 and 15 ( In the array orthogonal direction), the laser beam once forms an image in front of the light receiving element array 13 and then spreads on the image plane 13A.

In the design example 2 shown in FIG. 15, f '>
Since it is set to f, as shown in FIG.
In the direction orthogonal to the arrangement direction of 4 and 15 (orthogonal arrangement direction), the laser beam reaches the image plane 13A before image formation and spreads on the light receiving surface on the image plane 13A. On the other hand, in both the design examples 1 and 2, the light receiving element array 13 is installed on the image forming surface of the anamorphic lens 21 in the arrangement direction of the light emitting sources 14 and 15, so that an image is formed on the light receiving surface as a minute laser beam. . As a result, as a result, it is condensed on the light receiving surface as an oval (linear) laser beam. In the above-described design examples 1 and 2, the anamorphic lens 21 can be configured as a simple single lens.

Next, a third embodiment of the present invention will be described with reference to FIGS. In this embodiment, the light source 1
When the radius of curvature of the first surface on the side of 4, 15 is r ₁ , the radius of curvature of the second surface on the side of the light-receiving element array 13 is r ₂ , and the imaging magnification is m, the anamorphic lens 21 as a condensing unit.
Satisfies the condition (1) 0 <r ₁ <| r ₂ | (2) 2 ≦ m <20.

The condition (1) is that the first surface of the anamorphic lens 21 has a convex surface facing the light emitting sources 14 and 15 and the second surface has a radius of curvature less than that of the first surface in the arrangement direction of the light emitting sources 14 and 15. Is a condition for maintaining the distance from the object surface (arrangement surface of the semiconductor laser array 12) to the anamorphic lens 21 under the same imaging magnification. The condition (2) limits the imaging magnification m in the arrangement direction of the light emitting sources 14 and 15 to 2 or more and 20 or less.

Here, FIG. 16 to FIG. 16 show the relationship between the shape of the lens and the principal point. The lens includes those having an anamorphic shape which is a feature of the present invention and those not having the anamorphic shape, which will be described with the same reference numeral 21. This figure shows an anamorphic lens whose convex surface faces the light emitting sources 14 and 15. That is, the positions of the principal points H and H ′ of the lens 21 are
It changes depending on the meniscus degree of the lens 21. To be more precise, as shown in FIG.
Where d is the thickness, n is the refractive index, r _{1 is} the radius of curvature of the first surface, and r ₂ is the radius of curvature of the second surface, the position of the principal point H of the lens 21 on the object plane side (light emission source side). Is S ₁ H, that is, the distance S ₁ H between the first surface of the lens 21 and the object-plane-side principal point H is S ₁ H = −r ₁ · d / [n (r ₂ −r ₁ ) + (n− 1) · d] = − (n−1) · d · f / (n · r ₂ ) Keep the focal length f constant and r ₂
Considering the case of changing, r ₁ also changes according to the change of r ₂ , and S ₁ H shifts to the object surface 12A side in proportion to 1 / r ₂ as shown in FIG.

In FIG. 18, the solid line portion corresponds to the above condition (1), and S ₁ H is (n−1) · d ·
It is set smaller than f / (n · r ₀ ). Where r ₀
Is a biconvex shape with the first and second surfaces having the same curvature (see FIG. 16).
Radius of curvature of r ₁ = −r ₂ = r ₀ = (n−1) · [1 + √ (1-d /
n / f)] · f. Under the condition that the focal length f and the imaging magnification m are constant,
As shown in FIG. 19A, the smaller S ₁ H is,
Therefore, as 1 / r ₂ is larger, the lens 21 (an anamorphic lens with the convex surface facing the object surface 12 a side) is closer to the object surface 12
A can be separated from the (semiconductor arrangement surface of the laser array 12), on the contrary, as shown in FIG. 19 (b), S ₁ H
Is larger, and therefore 1 / r ₂ is smaller, it is necessary to dispose the lens 21 closer to the object surface 12A (arrangement surface of the semiconductor laser array 12) side.

The conjugate length L (semiconductor laser array 12
And the optical path length between the light-receiving element array 13 and L = (2 + m +
1 / m), and if m is increased under the condition that L is constant,
Although f and L decrease, as shown in FIG. 20, as S ₁ H is smaller, and thus 1 / r ₂ is larger, the lens arrangement position (the first surface of the object surface 12A and the first lens 21 of the lens 21) is maintained under the condition that L is constant. Since the optical object distance (distance between the object surface 12A and the object-side principal point H of the lens 21) can be reduced while keeping the same distance between the surface S ₁ ), the imaging magnification It is possible to increase m.

In this embodiment, as described above,
According to the condition (1), the position of the principal point H of the anamorphic lens 21 on the object plane 12A side is set to be located on the object plane 12A side. Therefore, the distance between the semiconductor laser array 12 and the anamorphic lens 21 is sufficiently large. Can be secured. Therefore, the interference of the optical components is less likely to occur, and the degree of freedom in arranging the optical components is increased. Further, the imaging magnification m can be set larger without changing the lens arrangement position and the conjugate length. Therefore, the arrangement accuracy of the components is relaxed, and the energy of the laser beam on the light receiving surface is reduced.

Further, the larger the imaging magnification m, the longer the conjugate length L, so that the apparatus becomes larger, and the smaller the imaging magnification m, the smaller the optical crosstalk, so that the arrangement accuracy of the light-receiving element array 12 is very strict. Become. Semiconductor laser array 13
The light emitting sources 14 and 15 are arranged at an arrangement pitch of p (0.05 to 0.
1 mm), the laser beam interval p ′ on the light receiving element array 13 is mp. As described above, the spacing p ′ between the laser beams on the light receiving surface is proportionally reduced as the imaging magnification m is reduced, and accordingly, the arrangement accuracy of the light receiving element array 13 becomes severe. Further, since the imaging performance deteriorates as the imaging magnification m decreases, it becomes difficult to form an image into a linear laser beam having a minute width proportional to the imaging magnification m. As a result, the arrangement accuracy of the light-receiving element array 13 becomes acceleratingly severe as the imaging magnification m decreases. Further, in consideration of changes with time and environmental changes, if m <2, the component placement accuracy becomes impractical. If m> 20, for example, the focal length f = 5.
When the length is mm, the conjugate length L exceeds 100 mm due to L≈ (2 + m + 1 / m), and the device becomes large. Further, the pitch p ′ of the laser beam on the light receiving element array 13
Is expanded to more than 2 mm, and the light receiving elements 16 and 1
The light receiving element array 13 having a large pitch of 7 is required. In this case, it is difficult to improve the response characteristics due to the increase of the light receiving area.

Here, a concrete set value of the anamorphic lens 21 in the present embodiment and an operation thereof will be described. First, set values of design examples 1 and 2 satisfying the condition (1) and comparative examples not satisfying the condition are shown.

In Design Example 1, in order to make the first surface of the anamorphic lens 21 a convex surface with respect to the object surface 12A side, the focal length f = 5 mm, the imaging magnification m = 5, the conjugate length L = 37 mm, and the refractive index n = 1. .5 radius of curvature r ₁ = 2.5 mm of the first surface of the anamorphic lens 21 in the arrangement direction of the light emission sources 14 and 15 radius of curvature r ₂ = ∞ of the second surface of the anamorphic lens 21 in the arrangement direction of the light emission sources 14 and 15 The distance d ₀ = 6 mm from the object surface 12A to the first surface of the anamorphic lens 21 was set to the wall thickness d ₁ = 3 mm of the anamorphic lens 21, and the distance d _{2 from} the second surface to the image surface 13A of the anamorphic lens 21 was set to d ₂ = 28 mm.

Similarly, in the design example 2, the focal length f = 3.556 mm, the imaging magnification m = 8, the conjugate length L = 37 mm, the refractive index n = 1.5, and the first anamorphic lens 21 in the array direction of the light emitting sources 14 and 15 is used. Curvature radius r ₁ = 1.778 mm Curvature radius r ₂ = ∞ of the second surface of the anamorphic lens 21 in the arrangement direction of the light emitting sources 14 and 15 Distance d ₀ = the object surface 12A to the first surface of the anamorphic lens 21 4 mm Thickness of anamorphic lens 21 d ₁ = 3 mm Distance from second surface of anamorphic lens 21 to image plane 13A d ₂ = 30 mm.

In the comparative example, the second surface of the lens 21 is changed to the image plane 13
In order to make it a convex surface to the A side, focal length f = 5 mm Imaging magnification m = 5 Conjugate length L = 37 mm Refractive index n = 1.5 First surface of anamorphic lens 21 in the arrangement direction of light emitting sources 14 and 15 Radius of curvature r ₁ = ∞ of the second surface of the anamorphic lens 21 in the arrangement direction of the light sources 14 and 15 r ₂ = −2.5 mm Distance between the object surface 12 A and the first surface of the anamorphic lens 21 d ₀ = 4 mm The thickness d _{1 of the} anamorphic lens 21 was 3 mm, and the distance d ₂ between the second surface of the anamorphic lens 21 and the image surface 13A was 30 mm.

With such a configuration, the design example 1 is compared with the comparative example. Focusing on d ₀ , the anamorphic lens 21 in the design example 1 is farther from the object plane 12A in spite of the same conjugate length L and the same imaging magnification, so that interference between components is less likely to occur. . In addition, the degree of freedom in arranging parts is increased. In the case of design example 2, the conjugate length L
In the example in which the imaging magnification m is increased under the same conditions as the comparative example and the arrangement position of the anamorphic lens 21, the component arrangement accuracy and the energy density of the laser beam on the light receiving element array 13 are higher than those of the comparative example. Will be reduced.

Further, a fourth embodiment of the present invention will be described with reference to FIGS. In this embodiment, an aspherical surface 2 which is rotationally symmetric with respect to the optical axis of the first surface of the anamorphic lens 21.
Since it is 1a and the second surface is the cylinder surface 21b, it can be easily machined by a lathe for precision machining or the like, and the mold can be easily machined when it is manufactured by molding. Therefore, it is excellent in mass productivity and can be manufactured at low cost. Further, by making the first surface an aspherical surface 21a,
The image forming performance in the arrangement direction of the light emitting sources 14 and 15 is good, and a bright optical system having a large numerical aperture NA can be obtained. Therefore, it is possible to realize a monitor optical system having a small optical crosstalk and a high light transmission efficiency.

A specific design example of the anamorphic lens 21 will be described below with reference to FIG. 22. The radius of curvature r _{1 of} the first surface (rotationally symmetric aspherical surface 21a) r ₁ =
2.5 mm Radius of curvature of the second surface (cylinder surface 21b) in the arrangement direction of the light sources 14 and 15 r _2x = ∞ Second surface (cylinder in the direction orthogonal to the arrangement direction of the light sources 14 and 15 (orthogonal direction)) Radius of curvature r _2y of surface 21b) = − 12 mm Distance from object surface 12A to first surface d ₀ = 6.667 mm Thickness of central portion d ₁ = 3 mm Distance from second surface to image surface 13A d ₂ = 18 mm Refractive index n = 1.5 Imaging magnification m = 3 Focal length f = 5 mm in the array direction of the light emitting sources 14 and 15 Focal length f ′ = 4.4 in the direction orthogonal to the array direction of the light emitting sources 14 and 15 (array orthogonal direction). 444 mm Conjugate length L = 27.667 mm Cone coefficient of first surface K = -1.70897 Second-order aspherical surface coefficient of the first surface A2 = 0.0 Fourth-order aspherical surface coefficient of first surface A4 = 6.212364 × 10 ^1-4 sixth order aspherical coefficients of the first surface A6 = 2.7709 × 10 ~ ⁵ 8-order aspherical coefficients of the first surface A8 = -1.10989 × 10
~ ⁵ 10th-order aspherical surface coefficient of the first surface A10 = 1.25761 × 1
It is defined as 0 to ^6.

Here, the height from the optical axis is h, and the aspherical surface 21
Let Z be the distance in the optical axis direction from the tangent plane of the aspherical vertex of the point on the aspherical surface 21a at the height h from the optical axis of a, and C (= 1 / r ₁ ) be the aspherical vertex curvature. One aspheric surface 2
The shape of 1a ^{is, Z = {Ch 2/1} + √ [1- (1 + K) · C 2]} + A 2
It is represented by the formula h ² + A ₄ h ⁴ + A ₆ h ⁶ + A ₈ h ⁸ + A ₁₀ h ¹⁰ .

The image forming performance (spherical aberration) of the anamorphic lens 21 designed as described above is shown in FIG.
As a comparative example, the first surface is a spherical surface (K, A2 to A10).
FIG. 23B shows the imaging performance of the lens with other setting values being the same as the above values. As shown in FIG. 23B, in the comparative example, a spherical aberration of -4 mm occurs when the lens numerical aperture NA is 0.1. However, in the present embodiment, the spherical aberration is as shown in FIG. As shown
Even when the lens numerical aperture NA is expanded to 0.25,
The spherical aberration is ± 3 μm or less, which indicates good imaging performance.

Therefore, the laser beam from the semiconductor laser array 12 is well focused on the light receiving element array 13 as a minute beam in the arrangement direction of the light emitting sources 14 and 15.
In the direction (orthogonal arrangement direction) orthogonal to the arrangement direction of the light emitting sources 14 and 15 while being imaged, f ′ <f is set, so that the image is once formed in front of the light receiving element array 13 and then diffused. Then, the light is received on the light receiving element array 13, and as a result, an image is formed as an elongated elliptical laser beam in a direction orthogonal to the arrangement direction of the light emitting sources 14 and 15 (orthogonal arrangement direction). This also applies when f '> f is set. Further, in this design example, the second surface is a convex cylinder surface 21b (r _2x = ∞, r _2y <0,
f ′ <f), but a concave cylinder surface (r _2x = ∞, r
Similar effects can be obtained when _2y > 0 and f '> f).

Next, a fifth embodiment of the present invention will be described with reference to FIG. Anamorphic lens 2 so far
The shape of 1 is an example of a combination of plane + cylinder surface, spherical surface (aspherical surface) + cylinder surface, but other than that, plane + cylinder surface (that is, cylinder lens), spherical surface (aspherical surface)
The anamorphic lens 21 can be configured by various combinations such as + toroidal surface, cylinder surface + cylinder surface, cylinder surface + toroidal surface, toroidal surface + toroidal surface. As shown in FIG. 24, the anamorphic lens 21 according to the present embodiment has two cylinder surfaces 21 whose power directions are orthogonal to each other. This anamorphic lens 21 is also shown in FIG.
As shown in FIG. 24A, the focal length is aligned with the image plane 13A in the arrangement direction of the light emitting sources 14 and 15, and FIG.
As shown in (b), in the direction orthogonal to the arrangement direction of the light emitting sources 14 and 15 (orthogonal arrangement direction), a slender elliptical laser beam is imaged on the image plane 13A. The same effect is obtained. In this case, r _1x
> 0, r _2y <0, r _1y = r _2x = ∞, or
It may be set such that r _1y > 0, r _2x <0, r _1x = r _2y = ∞. Such an anamorphic lens 21 also
Since both surfaces are cylinder surfaces 21b, mass productivity is excellent.

Further, a sixth embodiment of the present invention will be described with reference to FIGS. In this embodiment, a reanamorphic optical system is constituted by two lenses as the light converging means, and some specific examples will be described below.

FIG. 25 shows a light converging means 50 composed of a positive spherical lens 51 and a convex cylinder lens 52 which relate the object surface 12A and the image surface 13A in a substantially conjugate relationship. The convex cylinder lens 52 has no power in the arrangement direction of the light emitting sources 14 and 15 as shown in FIG. 25 (a), and as shown in FIG.
It has a positive power in the direction orthogonal to the array direction of 15 (array orthogonal direction).

FIG. 26 shows a light condensing means 53 which is composed of a positive spherical lens 51 and a concave cylinder lens 54 which bring the object surface 12A and the image surface 13A into a substantially conjugate relationship. The concave cylinder lens 54 has no power in the arrangement direction of the light emitting sources 14 and 15 as shown in FIG. 26 (a), and as shown in FIG.
In the direction orthogonal to the arrangement direction of 15 (orthogonal arrangement direction), it has a negative power.

FIG. 27 shows a light condensing means 55 which is composed of a positive spherical lens 51 and a convex cylinder lens 56 which bring the object surface 12A and the image surface 13A into a substantially conjugate relationship. The convex cylinder lens 56 has a positive power in the arrangement direction of the light sources 14 and 15 as shown in FIG. 27A, and the light source 1 as shown in FIG.
It has no power in the direction orthogonal to the arrangement direction of 4, 15 (orthogonal arrangement direction).

In FIG. 28, a positive spherical lens 51 and a concave cylinder lens 58 constitute a condenser means 57. The concave cylinder lens 56 has a negative power in the arrangement direction of the light emitting sources 14 and 15 as shown in FIG. 28A, and the light emitting source 1 as shown in FIG. 28B.
It has no power in the direction orthogonal to the arrangement direction of 4, 15 (orthogonal arrangement direction).

In the structure shown in FIGS. 25 to 28, the light source 1 is replaced by replacing the spherical lens with an aspherical lens.
The imaging performance in the arrangement direction of 4, 15 can be further improved.

As described above, by combining the spherical lens or the aspherical lens with the cylinder lens,
An anamorphic optical system having a small number of parts and a simple structure can be obtained without using a special lens. This is an action corresponding to the invention of claim 7.

In the condensing means 60 shown in FIG. 29, two cylinder lenses whose power-free directions are orthogonal to each other in the arrangement direction of the light emitting sources 14 and 15 and the direction orthogonal to the direction (orthogonal arrangement direction). It is composed of 61 and 62.

The above focusing means 50, 53, 55, 57,
Since 60 is composed of a combination of lenses having simple shapes, it is possible to realize an anamorphic optical system with commercially available lenses. Of course, the toroidal lens can also be configured by combining a spherical lens and a cylinder lens.

Further, a seventh embodiment of the present invention will be described with reference to FIGS. 30 and 31. In FIG. 30, a function of a cylinder mirror is added to the half mirror 20 that splits the laser beam from the semiconductor laser array 12, and the half mirror 20 and a rotationally symmetric spherical or aspherical lens 63 condense or condense the laser beam. Forming the diverging light collecting means 64, the light collecting means 6 in the arrangement direction of the light emitting sources 14 and 15
The light receiving element array (image surface 13A) is arranged in the vicinity of the image forming surface of No. 4, which is a configuration corresponding to the invention of claim 8.

In FIG. 31, the function of a cylinder mirror is added to the mirror 23 for folding back the optical path of the laser beam, and the mirror 23 and a rotationally symmetric spherical or aspherical lens 63 condense or diverge the laser beam. And a light receiving element array (image plane 13) near the image forming plane of the light collecting means 65 in the arrangement direction of the light emitting sources 14 and 15.
A) is arranged, which is another configuration corresponding to the invention of claim 8.

Half mirror 20 in FIG. 30 and FIG.
The function of the cylinder mirror included in the mirror 23 in No. 1 is such that both have power in the arrangement direction of the light emitting sources 14 and 15 and no power in the direction orthogonal to the arrangement direction (orthogonal arrangement direction). However, a configuration in which the direction of power is reversed is also possible. Further, the function added for condensing light is not limited to the function as the cylinder mirror, but may be the function of the toroidal mirror.

As described above, the half mirror 20 or the folding mirror 23 is also used as a part of the light collecting means 64, 65, so that an anamorphic optical system having a small number of parts and a simple structure can be obtained. This is an action corresponding to the invention of claim 8.

Further, an eighth embodiment of the present invention will be described with reference to FIGS. 32 and 33. In the present embodiment, a collimator lens 66, which is a component of the light collecting means, is provided between the semiconductor laser array (object surface 12A) and the half mirror 20, and the light collecting means are connected in the arrangement direction of the light emitting sources 14 and 15. The light receiving element array (image surface 13A) is arranged near the image surface.

That is, FIG. 32 shows a cylinder lens 67 which allows the laser beam split by the half mirror 20 to pass therethrough.
And the collimator lens 66 forms the light collecting means 68. FIG. 33 shows an example in which the function of a cylinder mirror is added to the folding mirror 23, and a condensing means 69 is formed by the mirror 23 and the collimator lens 66.

In any of the examples shown in FIGS. 32 and 33, the parallel light from the collimator lens 66 is converted into the cylinder lens 67 (FIG. 32) or the folding mirror 23 (FIG. 3).
Due to the function of the cylinder mirror of 3), the light emission source 1
In the array direction of 4, 15, the light receiving element array (image plane 1
3A), and in the direction orthogonal to the arrangement direction of the light emission sources 14 and 15 (orthogonal arrangement direction), the image plane 1 remains as parallel light.
3A is irradiated, and as a result, a linear laser beam is formed on the image plane 13A. Therefore, the anamorphic optical system can be configured with a small number of parts.

Further, a ninth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the harmful light is removed by the slit 70 by disposing the slit 70 in the vicinity of the image plane of the anamorphic lens 21 in the direction orthogonal to the arrangement direction of the light emitting sources 14 and 15 (orthogonal arrangement direction).
It is possible to prevent the adverse effect of flare light on the optical crosstalk. This is an action corresponding to the invention of claim 9, but the light emitting sources 14, 1 are determined from the focal length f of the anamorphic lens 21 in the arrangement direction of the light emitting sources 14, 15.
It is applied when the focal length f ′ in the direction orthogonal to the arrangement direction of 5 (the arrangement orthogonal direction) is small.

Further, as shown in FIG. 11A, a concave lens 46 is provided on the light receiving element array 13 or, as shown in FIG.
As shown in (b), even if a lens having a negative power such as the grating lens 47 is used, the light receiving element array 1
It is also possible to defocus the laser beam in the direction perpendicular to the arrangement with respect to 3 and form a linear image.

Next, a tenth embodiment of the present invention will be described with reference to FIGS. This embodiment is an optical scanning device 80 using the multi-beam light source device 10 described above.
And corresponds to the invention described in claims 10 and 11. Aperture 30 of multi-beam light source device 10
In the optical path between the polygon mirror 82 as a deflector driven by the motor 81 and the pair of cylinder lenses 8 having a curvature only in the sub-scanning direction orthogonal to the main scanning direction.
3,84 are arranged. Multi-beam light source device 10
The cylinder lens 83 on the side is a positive lens, and the cylinder lens 84 on the side of the polygon mirror 82 is a negative lens. Further, in the optical path between the polygon mirror 82 and the surface 85 to be scanned such as an image carrier, an fθ lens 86, a mirror 87,
A toroidal lens 88 for surface tilt correction is arranged.

Scanning of the beam onto the surface to be scanned 85 in such a structure will be described. The laser beam collimated by the collimator lens 29 of the multi-beam light source device 10 is shaped by the aperture 30 whose opening 31 is a perfect circle, and further, the beam diameter is changed by the pair of cylinder lenses 83 and 84 having a curvature only in the sub-scan. Is converted to form an image on the polygon mirror 82. The laser beam deflected by the rotation of the polygon mirror 82 forms a spot on the scanned surface 85 via the fθ lens 86, the mirror 87 and the toroidal lens 88.

In this case, the interval between the spots on the surface to be scanned 85 in the sub-scanning direction is set by rotating the multi-beam light source device 10 around the optical axis according to the writing density.

[0105]

According to the present invention, the beams from a plurality of light emitting sources of the semiconductor laser array are divided into two by the optical path separating means, and the divided beams are condensed by the condensing means to each light receiving element of the light receiving element array. In the multi-beam light source device that controls the output of the semiconductor laser array according to the amount of light that is incident on the light receiving element array, the aperture is provided in the optical path from the semiconductor laser array to the light receiving element array. Even if there is variation in the divergence angle of the laser beam emitted from the light emitting source, the beam diameter imaged on the light receiving element array can be made uniform by the aperture. Therefore, in terms of optical crosstalk, frequency response, etc. It is possible to obtain stable performance.

According to a second aspect of the present invention, the beams from a plurality of light emitting sources of the semiconductor laser array are divided into two by the optical path separating means, and the divided beams are incident on each light receiving element of the light receiving element array by the light converging means. In the multi-beam light source device for controlling the output of the semiconductor laser array according to the amount of light input to the light receiving element array, a mirror whose reflection angle is changed by the optical axis changing means in the optical path from the semiconductor laser array to the light receiving element array. Since the optical axis changing means changes the direction of the folding mirror that reflects the laser beam emitted from the semiconductor laser array to the light receiving element array, it is possible to adjust the mounting position of the light collecting means and the radiation surface accuracy. The optical axis shift that occurs can be corrected by a mirror, which minimizes optical crosstalk,
It is possible to secure a margin for the optical axis shift with time and the eccentricity of the optical element.

According to a third aspect of the present invention, the beams from a plurality of light emitting sources of the semiconductor laser array are divided into two by the optical path separating means, and the divided beams are incident on each light receiving element of the light receiving element array by the light converging means. In the multi-beam light source device that controls the output of the semiconductor laser array according to the amount of light input to the light-receiving element array, a support that holds the semiconductor laser array and at least a part of an output control circuit that drives the semiconductor laser array and Since the substrate having the light receiving element array is provided, the light receiving surface of the light receiving element array is brought into contact with the support, and the support and the substrate are coupled so as to be relatively displaceable along the arrangement direction of the light emitting source, the output By providing the light receiving element array on the substrate on which the control circuit is formed, it is possible to reduce disturbance factors and stabilize the output control of the semiconductor laser array. Needless to say, the optical path length between the semiconductor laser array and the light receiving element array can be accurately determined by bringing the light receiving surface of the light receiving element array into contact with the support that holds the semiconductor laser array. You can
Further, since the substrate and the support can be relatively displaced along the arrangement direction of the light emitting sources, the center of the beam spot can be aligned with a desired position of the light receiving element array.

According to a fourth aspect of the present invention, the beams from a plurality of light emitting sources of the semiconductor laser array are divided into two by the optical path separating means, and the divided beams are incident on each light receiving element of the light receiving element array by the light converging means. However, in the multi-beam light source device that controls the output of the semiconductor laser array by the amount of light input to the light receiving element array, since the concave groove located on the dividing line of the light receiving element is formed in the protective cover of the light receiving element array, Therefore, the margin of optical crosstalk can be increased.

According to a fifth aspect of the present invention, a semiconductor laser array having a plurality of light emitting sources, an optical path separating means for dividing a plurality of laser beams from the light emitting sources into two, and a plurality of lasers divided by the optical path separating means. Separate the beams into elliptical shapes that are long in the direction orthogonal to the direction in which the light sources are arranged.
Since the light collecting means for collecting light and the light receiving element array in which the plurality of light receiving elements corresponding to the light emitting sources are arranged in parallel with the arrangement direction of the light emitting sources are used, the plurality of lasers from the semiconductor laser array are arranged by the optical path separating means. Part of the beam is separated as output control light, and the light is condensed and condensed into a long elliptical laser beam in the direction orthogonal to the array direction of the light emission sources and guided to each light receiving element of the light receiving element array. As a result, the energy density of the received beam can be reduced while maintaining good optical crosstalk, and therefore good frequency response can be maintained without significantly increasing the imaging magnification. Therefore, it is possible to reduce the size and perform high-speed and high-accuracy output control.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, a single-lens anamorphic lens is used as the light-collecting means, and the light-receiving element array is arranged in the vicinity of the image plane of the anamorphic lens in the arrangement direction of the light-emitting sources. Therefore, with a single anamorphic lens, multiple laser beams from the semiconductor lens array can be imaged as independent elliptical beams on each light receiving element of the light receiving element array, which simplifies the optical system. The cost can be reduced by reducing the size of the optical component, and the space for arranging the optical components can be small, so that the miniaturization can be promoted.

According to the invention described in claim 7, in the invention described in claim 5, since the condensing means is formed by a spherical lens or an aspherical lens which is rotationally symmetric with respect to the optical axis, and a cylinder lens, a special lens is used. An anamorphic optical system capable of linear imaging can be easily configured without using it.

According to an eighth aspect of the invention, in the fifth aspect of the invention, a converging means is formed by a rotationally symmetric spherical or aspherical lens and a mirror for condensing or diverging the laser beam, and the mirror is formed. Since the light receiving element array is formed integrally with the mirror for folding the optical path or the optical path separating means and the light receiving element array is arranged in the vicinity of the image forming surface of the condensing means in the arrangement direction of the light emitting source, the light is condensed on the optical path separating means or the folding mirror. Since the lens action of the system can be performed, the number of parts of the anamorphic optical system can be reduced and the configuration can be simplified.

The invention according to claim 9 is the invention according to claim 5, 6, or 7.
Alternatively, in the invention described in Item 8, since the slit is provided in the vicinity of the image forming surface of the condensing means in the direction orthogonal to the arrangement direction of the light emitting sources of the semiconductor laser array, the flare light is effectively shielded without blocking the effective light. The optical crosstalk can be reduced.

According to a tenth aspect of the invention, the beams from a plurality of light emitting sources of the semiconductor laser array are divided into two by the optical path separating means, and the divided beams are incident on each light receiving element of the light receiving element array by the light converging means. A multi-beam light source device for controlling the output of the semiconductor laser array according to the amount of light input to the light-receiving element array is provided between the collimator lens and the deflector for collimating the other beams split by the optical path separating means. Since a perfect circular aperture and a pair of cylinder lenses having a curvature only in the direction orthogonal to the scanning direction are provided, when the laser beam from the semiconductor laser array is scanned on the surface to be scanned by the deflector, the aperture is By providing an optical system that is easily combined with a cylinder lens, it is possible to rotate the multi-beam light source device around the optical axis. To, in the sub-scanning direction without changing the beam diameter is a laser beam in the main scanning direction can be shaped by a pair of cylinder lenses.

According to the eleventh aspect of the present invention, in the tenth aspect of the invention, the cylinder lens located on the semiconductor laser array side is rotatably supported about the optical axis. By rotating the cylinder lens on the side of the beam light source device around the optical axis, it is possible to adjust the interval between the scanning lines, which facilitates replacement of the multi-beam light source device and improves maintainability.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a multi-beam light source device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing how a beam diameter emitted from a multi-beam light source device is shaped by an aperture.

FIG. 3 is a perspective view showing an optical axis adjusting means of a mirror.

FIG. 4 is an exploded perspective view showing an assembly structure of a multi-beam light source device.

FIG. 5 is an exploded perspective view showing a relationship between a support and a substrate of the multi-beam light source device.

FIG. 6 is a circuit diagram of a control system of each semiconductor laser.

FIG. 7 is a circuit diagram of an output system of a semiconductor laser array.

FIG. 8 is an optical path diagram showing the action of an aperture arranged near the image forming plane of the light collecting means.

FIG. 9 is a perspective view showing an image forming action of the light collecting means.

FIG. 10 is an optical path diagram showing an image forming action of the light collecting means.

11A is a perspective view of a concave lens provided in the light receiving element array, and FIG. 11B is a perspective view of a grating provided in the light receiving element array.

12A and 12B show a state in which a groove is formed in the protective cover of the light receiving element array, FIG. 12A being a front view and FIG. 12B being a side view.

FIG. 13 is an optical path diagram showing a light collecting action according to the second embodiment of the present invention.

FIG. 14 is an optical path diagram showing a condensing action.

FIG. 15 is an optical path diagram showing a condensing function.

FIG. 16 is an explanatory diagram showing a relationship between a lens shape and a principal point according to a third example of the present invention.

FIG. 17 is an explanatory diagram showing a relationship between a lens shape and a principal point.

FIG. 18 is a graph showing the relationship between the lens shape and the principal point.

FIG. 19 is an explanatory diagram showing the relationship between the change in the position of the principal point and the position of the lens.

FIG. 20 is an explanatory diagram showing changes in the distance between the light emitting source and the principal point due to changes in the position of the principal point.

FIG. 21 is a perspective view showing the image forming action of the light collecting means according to the fourth example of the present invention.

FIG. 22 is an optical path diagram showing the image forming action of the light collecting means.

FIG. 23 is an explanatory diagram showing the imaging performance of the light collecting means.

FIG. 24 is an optical path diagram showing the converging action of the condensing means according to the fifth example of the present invention.

FIG. 25 is an optical path diagram showing the converging function of the condensing means according to the sixth embodiment of the present invention.

FIG. 26 is an optical path diagram showing the light collecting action of the light collecting means.

FIG. 27 is an optical path diagram showing the light collecting action of the light collecting means.

FIG. 28 is an optical path diagram showing the light collecting action of the light collecting means.

FIG. 29 is an optical path diagram showing the light collecting action of the light collecting means.

FIG. 30 is an optical path diagram showing a condensing function of the condensing unit according to the seventh embodiment of the present invention.

FIG. 31 is an optical path diagram showing the light collecting action of the light collecting means.

FIG. 32 is an optical path diagram showing a condensing function of the condensing unit according to the eighth embodiment of the present invention.

FIG. 33 is an optical path diagram showing the light collecting action of the light collecting means.

FIG. 34 is an optical path diagram showing the action of the slit according to the ninth embodiment of the present invention.

FIG. 35 is a perspective view of an optical scanning device according to a tenth embodiment of the present invention.

FIG. 36 is an optical path diagram showing the scanning operation of the optical scanning device.

FIG. 37 is a perspective view showing the outline of a conventional optical scanning device.

FIG. 38 is a cross-sectional view showing a structure for detecting the light emission amount of a conventional semiconductor laser array.

39A is a characteristic diagram showing a relationship between eccentricity in the array direction of the light receiving elements and optical crosstalk, and FIG. 39B is a schematic diagram showing a relationship between the semiconductor laser and the light receiving elements.

FIG. 40 is a characteristic diagram showing a relationship between a beam spot diameter and a cutoff frequency.

FIG. 41 is an explanatory diagram showing a conventional example in which a prism is used as a means for adjusting the incident light beam diameter to the scanning optical system.

FIG. 42 is an explanatory diagram showing a conventional example in which a beam compressor is used as a means for adjusting the incident light beam diameter to the scanning optical system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Multi-beam light source device 11 Substrate 12 Semiconductor laser array 13 Light receiving element array 14,15 Light emitting source 16,17 Light receiving element 19 Support 20 Optical path separating means 21 Condensing means, anamorphic lens 22 Aperture 23 Mirror 27 Optical axis changing means 29 Collimator Lens 30 Aperture 48 Protective cover 49 Groove 50 Condensing means 51 Spherical lens 52 Cylinder lens 53 Condensing means 54 Cylinder lens 55 Condensing means 56,58 Cylinder lens 57,60 Condensing means 61,62 Cylinder lens 63 Aspherical lens 64 , 65 Condensing means 66 Collimator lens 67 Cylinder lens 68, 69 Condensing means 70 Slit 82 Deflector 83, 84 Cylinder lens

Claims (11)

[Claims] 1. A semiconductor laser array having a plurality of light emitting sources, an optical path separating means for dividing a beam from the light emitting sources into two, a condensing means for converging the beams divided by the optical path separating means, and the light emission. A light-receiving element array having a plurality of light-receiving elements corresponding to a light source and arranged at a focus position of the light-collecting means, and controlling the output of the semiconductor laser array by the amount of light input to the light-receiving element array. In the multi-beam light source device, an aperture is provided in an optical path from the semiconductor laser array to the light receiving element array. 2. A semiconductor laser array having a plurality of light emitting sources, an optical path separating means for dividing a beam from the light emitting sources into two, a condensing means for converging the beams divided by the optical path separating means, and the light emission. A light-receiving element array having a plurality of light-receiving elements corresponding to a light source and arranged at a focus position of the light-collecting means, and controlling the output of the semiconductor laser array by the amount of light input to the light-receiving element array. In the multi-beam light source device described above, a mirror whose reflection angle is changed by an optical axis changing means is provided in the optical path from the semiconductor laser array to the light receiving element array. 3. A semiconductor laser array having a plurality of light emitting sources, an optical path separating means for dividing a beam from the light emitting sources into two, a condensing means for converging the beams divided by the optical path separating means, and the light emission. A light-receiving element array having a plurality of light-receiving elements corresponding to a light source and arranged at a focus position of the light-collecting means, and controlling the output of the semiconductor laser array by the amount of light input to the light-receiving element array. In the multi-beam light source device, a support body holding the semiconductor laser array, a substrate having at least a part of an output control circuit for driving the semiconductor laser array and the light receiving element array are provided, and the light receiving element array The light receiving surface is brought into contact with the support, and the support and the substrate are coupled so as to be relatively displaceable along the arrangement direction of the light emitting sources. Multi-beam light source device. 4. A semiconductor laser array having a plurality of light emitting sources, an optical path separating means for dividing a beam from the light emitting sources into two, a condensing means for converging the beams divided by the optical path separating means, and the light emission. A light-receiving element array having a plurality of light-receiving elements corresponding to a light source and arranged at a focus position of the light-collecting means, and controlling the output of the semiconductor laser array by the amount of light input to the light-receiving element array. In the multi-beam light source device described above, a concave groove located on the dividing line of the light receiving element is formed in the protective cover of the light receiving element array. 5. A semiconductor laser array having a plurality of light emitting sources, an optical path separating means for dividing a plurality of laser beams from the light emitting sources into two, and a plurality of laser beams divided by the optical path separating means. A condensing means for separating and condensing into a long ellipse in a direction orthogonal to the direction in which the light sources are arranged, and a plurality of light receiving elements corresponding to the light emission sources are arranged in parallel with the arrangement direction of the light emission sources. A multi-beam light source device comprising a light receiving element array. 6. The multi-beam according to claim 5, wherein a single-lens anamorphic lens is used as the condensing means, and the light receiving element array is arranged in the vicinity of the image plane of the anamorphic lens in the arrangement direction of the light emitting sources. Light source device. 7. The multi-beam light source device according to claim 5, wherein a condensing means is formed by a spherical lens or an aspherical lens which is rotationally symmetric with respect to the optical axis, and a cylinder lens. 8. A focusing means is formed by a rotationally symmetric spherical or aspherical lens and a mirror for focusing or diverging a laser beam, and the mirror is formed integrally with a mirror for folding an optical path or an optical path separating means. 6. The multi-beam light source device according to claim 5, wherein a light receiving element array is arranged in the vicinity of the image forming surface of the light converging means in the arrangement direction of the light emitting sources. 9. The multi-beam according to claim 5, 6, 7 or 8, wherein a slit is provided in the vicinity of the image plane of the condensing means in the direction orthogonal to the arrangement direction of the light emitting sources of the semiconductor laser array. Light source device. 10. A semiconductor laser array having at least a plurality of light emitting sources, an optical path separating means for dividing a beam from the light emitting sources into two, and a condensing means for converging the beams divided by the optical path separating means. A multi-beam light source device including a light-receiving element array having a plurality of light-receiving elements corresponding to the light-emitting source and controlling the output of the semiconductor laser array according to the input light quantity is provided, and the multi-beam light source device is divided by the optical path separating means. An optical scanning device characterized in that a perfect circular aperture and a pair of cylinder lenses having a curvature only in a direction orthogonal to the scanning direction are provided between a collimator lens for collimating the beam and the deflector. 11. The optical scanning device according to claim 7, wherein a cylinder lens located on the semiconductor laser array side is supported rotatably about an optical axis.