JP2009038227A - Light source unit, optical scanning apparatus, image forming apparatus, optical transmission module and optical transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain excellent laser quality and light utilization efficiency without increasing costs. <P>SOLUTION: The light source unit 10 is provided with a semiconductor laser module 10A including a semiconductor laser 10a, and an optical module 10B including a half mirror 10c, a collimator lens 10d and an aperture plate 10e. Light emitted from the surface emitting laser array chip of the semiconductor laser 10a is made incident on the half mirror 10c through only an air layer, and the light transmitted through the half mirror 10c is outputted from the light source unit 10 through the collimator lens 10d and the aperture plate 10e. In such a manner, the light emitted from the surface emitting laser array chip is directly made incident on the optical module 10B without interposing a sealing glass material or the like. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light source unit, an optical scanning device, an image forming apparatus, an optical transmission module, and an optical transmission system, and more specifically, a light source unit including a semiconductor laser, an optical scanning device having the light source unit, and the optical scanning device. The present invention relates to an image forming apparatus, an optical transmission module including the light source unit, and an optical transmission system including the optical transmission module.

  A semiconductor laser is small and has low power consumption, and is widely used as a light source for optical communication, a light source for writing and reading information on an optical disk, a light source for writing in an electrophotographic system, and the like.

  The semiconductor laser is mounted in a package according to the application, and after being electrically connected by wire bonding, an emission part is hermetically sealed with a glass material, an optical fiber, or the like. This hermetic sealing takes environmental resistance into consideration, and generally encloses dry air or nitrogen gas. The component on which the semiconductor laser is mounted in this manner is also called a semiconductor laser module.

  For example, for optical communication, the semiconductor laser module is optically coupled to an optical fiber. In applications such as an optical pickup device, an electrophotographic system, and a sensor, a CAN package type or a flat package type semiconductor laser module is widely used. Incidentally, a combination of this semiconductor laser module and an optical module is also called a light source unit.

  For example, Patent Document 1 discloses a light in which an optical element, a first lens, an optical isolator for suppressing reflected return light, and an optical fiber that inputs and outputs an optical signal are housed in a package in this order. An isolator built-in optical element module is disclosed. In this optical element module with a built-in optical isolator, the first lens and the optical isolator are placed on a substantially flat fixing member so that their optical axes coincide with each other.

  Further, Patent Document 2 discloses a semiconductor laser device that is used as excitation light for reading out radiation image information recorded on a stimulable phosphor sheet by extending the emitted laser light into a linear shape. . The semiconductor laser device includes a semiconductor laser chip that emits laser light, a package that houses the semiconductor laser chip, and a surface provided on the package for transmitting the laser light emitted from the semiconductor laser chip. An emission window coated with an antireflection film, and the reflectance of the antireflection film with respect to the oscillation wavelength of the laser light is 1.0% or less.

  Further, Patent Document 3 discloses a semiconductor laser chip, a package that houses the semiconductor laser chip, a sealing transparent member that is provided on the upper surface of the package and from which light emitted from the front end surface of the semiconductor laser chip is extracted. An optical semiconductor device having the above is disclosed. In this optical semiconductor device, a light-receiving element for monitoring the intensity of light emitted from the semiconductor laser chip is provided on the sealing transparent member, and the light output of the semiconductor laser chip is controlled in accordance with the monitor current of the light-receiving element.

  In any of the modules and apparatuses disclosed in Patent Documents 1 to 3, light is output via a transparent member.

  In recent years, a new type of semiconductor laser called a surface emitting laser and a semiconductor laser module mounted with the same have begun to be commercialized. In this surface-emitting laser, a semiconductor multilayer film reflecting mirror formed by crystal growth on a substrate is used as a resonator mirror to resonate in a direction perpendicular to the substrate. Therefore, unlike the conventional edge-emitting laser, there is an advantage that the cleaving operation for forming the resonator is unnecessary and the inspection at the wafer level is possible, so that the manufacturing cost is low. The surface emitting laser has many excellent characteristics such as (1) low threshold current, (2) single longitudinal mode, and (3) circular emission beam. Therefore, by using a surface emitting laser, it is possible to obtain a high-performance and low-cost semiconductor laser module and light source unit.

JP 2000-19358 A JP 2005-72448 A Japanese Patent Laid-Open No. 11-273138

  By the way, when a part of the light emitted from the semiconductor laser is incident on the semiconductor laser as return light, the laser characteristics are adversely affected such that the laser operation becomes unstable or the radiation angle changes.

  Therefore, in Patent Document 1 and Patent Document 2, the sealing glass material is coated with an antireflection film. In Patent Document 3, a countermeasure against return light is taken by providing an optical isolator.

  However, in general, an optical isolator is expensive and causes an increase in cost. In addition, the antireflection film needs to be precisely controlled in film thickness for the target wavelength, and in order to increase the light transmittance, it is necessary to perform multi-layer coating. Get higher.

  A surface emitting laser has excellent characteristics in many respects, but generally has a lower output than an end surface laser. In particular, the output obtained by the fundamental transverse mode oscillation is usually about 1 to 2 mW, and a slight loss due to optical components cannot be ignored. By the way, even if the anti-reflection film is coated on the sealing glass material, the light transmittance is lowered, so that a reflection loss occurs and the light utilization efficiency is lowered.

  Further, in the conventional light source unit, the individually manufactured semiconductor laser module and optical module are attached to a common holding material. Therefore, it is necessary to adjust the position and tilt angle during assembly.

  The present invention has been made under such circumstances, and a first object of the present invention is to provide a light source unit excellent in laser quality and light utilization efficiency without incurring an increase in cost.

  A second object of the present invention is to provide an optical scanning device capable of performing optical scanning with high accuracy without causing an increase in cost.

  A third object of the present invention is to provide an image forming apparatus capable of forming a high-quality image without increasing the cost.

  A fourth object of the present invention is to provide an optical transmission module capable of generating a high-quality optical signal without increasing the cost.

  A fifth object of the present invention is to provide an optical transmission system capable of performing high-quality optical transmission without increasing the cost.

  According to a first aspect of the present invention, there is provided a semiconductor laser module including a semiconductor laser having at least one light emitting portion; and the light emitted from the semiconductor laser directly in contact with the semiconductor laser module only through an air layer A light source unit comprising: an incident optical module;

  According to this, the optical module is in contact with the semiconductor laser module, and the light emitted from the semiconductor laser is directly incident only through the air layer. In this case, the conventional sealing glass material is unnecessary. Therefore, it is possible to obtain excellent laser quality and light utilization efficiency without incurring high costs.

  According to a second aspect of the present invention, there is provided an optical scanning device that scans a surface to be scanned with light, the light source unit of the present invention; a deflector that deflects light from the light source unit; and the polarizer. And a scanning optical system for condensing the deflected light on the surface to be scanned.

  According to this, since the light source unit of the present invention is provided, as a result, it is possible to perform optical scanning with high accuracy without increasing the cost.

  According to a third aspect of the present invention, there is provided at least one image carrier; and at least one optical scanning device according to the invention that scans the at least one image carrier with light including image information. An image forming apparatus provided.

  According to this, since at least one optical scanning device of the present invention is provided, as a result, it is possible to form a high-quality image without increasing the cost.

  According to a fourth aspect of the present invention, there is provided an optical transmission module for generating an optical signal corresponding to an input electric signal, the light source unit of the present invention; and the semiconductor laser of the light source unit being input. An optical transmission module comprising: a driving device that is driven according to an electrical signal.

  According to this, since the light source unit of the present invention is provided, as a result, a high-quality optical signal can be generated.

  According to a fifth aspect of the present invention, an optical transmission module of the present invention; an optical transmission medium that transmits an optical signal generated by the optical transmission module; and an optical signal that passes through the optical transmission medium is converted into an electrical signal. An optical transmission system comprising: a converter for converting.

  According to this, since the optical transmission module of the present invention is provided, as a result, high-quality optical transmission can be performed without increasing the cost.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a printer 1000 as an image forming apparatus according to an embodiment of the present invention.

  The laser printer 1000 includes an optical scanning device 1010, a photosensitive drum 1030, a charging charger 1031, a developing roller 1032, a transfer charger 1033, a charge removal unit 1034, a cleaning blade 1035, a toner cartridge 1036, a paper feeding roller 1037, a paper feeding tray 1038, A registration roller pair 1039, a fixing roller 1041, a paper discharge roller 1042, a paper discharge tray 1043, and the like are provided.

  A photosensitive layer is formed on the surface of the photosensitive drum 1030. That is, the surface of the photoconductor drum 1030 is a scanned surface. Here, the photosensitive drum 1030 rotates in the direction of the arrow in FIG.

  The charging charger 1031, the developing roller 1032, the transfer charger 1033, the charge removal unit 1034, and the cleaning blade 1035 are each arranged in the vicinity of the surface of the photosensitive drum 1030. Then, with respect to the rotation direction of the photosensitive drum 1030, the charging charger 1031 → the developing roller 1032 → the transfer charger 1033 → the charge eliminating unit 1034 → the cleaning blade 1035 are arranged in this order.

  The charging charger 1031 uniformly charges the surface of the photosensitive drum 1030.

  The optical scanning device 1010 irradiates the surface of the photosensitive drum 1030 charged by the charging charger 1031 with light modulated based on image information from a host device (for example, a personal computer). As a result, a latent image corresponding to the image information is formed on the surface of the photosensitive drum 1030 on the surface of the photosensitive drum 1030. The latent image formed here moves in the direction of the developing roller 1032 as the photosensitive drum 1030 rotates. The configuration of the optical scanning device 1010 will be described later.

  The toner cartridge 1036 stores toner, and the toner is supplied to the developing roller 1032.

  The developing roller 1032 causes the toner supplied from the toner cartridge 1036 to adhere to the latent image formed on the surface of the photosensitive drum 1030 to visualize the image information. Here, the latent image to which the toner is attached (hereinafter also referred to as “toner image” for the sake of convenience) moves in the direction of the transfer charger 1033 as the photosensitive drum 1030 rotates.

  Recording paper 1040 is stored in the paper feed tray 1038. A paper feed roller 1037 is disposed in the vicinity of the paper feed tray 1038, and the paper feed roller 1037 takes out the recording paper 1040 one by one from the paper feed tray 1038 and conveys it to the registration roller pair 1039. The registration roller pair 1039 temporarily holds the recording paper 1040 taken out by the paper supply roller 1037, and in the gap between the photosensitive drum 1030 and the transfer charger 1033 according to the rotation of the photosensitive drum 1030. Send it out.

  A voltage having a polarity opposite to that of the toner is applied to the transfer charger 1033 in order to electrically attract the toner on the surface of the photosensitive drum 1030 to the recording paper 1040. With this voltage, the toner image on the surface of the photosensitive drum 1030 is transferred to the recording paper 1040. The recording sheet 1040 transferred here is sent to the fixing roller 1041.

  In the fixing roller 1041, heat and pressure are applied to the recording paper 1040, whereby the toner is fixed on the recording paper 1040. The recording paper 1040 fixed here is sent to the paper discharge tray 1043 via the paper discharge roller 1042 and is sequentially stacked on the paper discharge tray 1043.

  The neutralization unit 1034 neutralizes the surface of the photosensitive drum 1030.

  The cleaning blade 1035 removes toner (residual toner) remaining on the surface of the photosensitive drum 1030. The removed residual toner is used again. The surface of the photosensitive drum 1030 from which the residual toner has been removed returns to the position of the charging charger 1031 again.

  Next, the configuration of the optical scanning device 1010 will be described.

  As shown in FIG. 2, the optical scanning device 1010 includes a light source unit 10, a coupling lens 11, an aperture plate 12, a cylindrical lens 13, a polygon mirror 14, an fθ lens 15, a toroidal lens 16, two mirrors (17, 18), and a control device (not shown) for comprehensively controlling the above-described units.

  As an example, the light source unit 10 includes a semiconductor laser module 10A and an optical module 10B as shown in FIG. In this specification, the light output direction from the light source unit 10 is described as the Z-axis direction, and two directions orthogonal to each other in a plane perpendicular to the Z-axis direction are described as the X-axis direction and the Y-axis direction.

  The semiconductor laser module 10A includes a semiconductor laser 10a, a laser control device (not shown) that drives and controls the semiconductor laser 10a, and a PCB (Printed Circuit Board) substrate 10b on which the semiconductor laser 10a and the laser control device are mounted. ing. Here, as an example of the semiconductor laser 10a, as shown in FIG. 4B, FIG. 5A and FIG. 5B, which is a cross-sectional view taken along line A-A in FIG. A package mounted on a flat package 21 called CLCC (Ceramic leaded chip carrier) is used. The flat package 21 has a multilayer structure of ceramic and metal wiring. In FIG. 4, FIG. 5 (A), and FIG. 5 (B), in order to avoid complication, illustration of the bonding wire which connects surface emitting laser array chip LA and metal wiring is abbreviate | omitted.

  As an example, as shown in FIG. 5A, the metal wiring extends from the periphery of the package toward the center, and is independently connected to the metal casters 22 on the side of the package in a one-to-one relationship. A die attach area DA provided with a metal film at the center of the package serves as a common electrode. Here, eight metal wirings located at four corners are connected to the die attach area DA. The surface emitting laser array chip LA is die-bonded to the die attach area DA using a solder material such as AuSn.

  As an example, the surface-emitting laser array chip LA includes an element unit including a plurality of light-emitting units provided at the center and a plurality of electrode pads provided around the center, as shown in FIG. Each light emitting unit emits a laser beam having a wavelength of 780 nm.

  Here, as shown in FIG. 7, the element units are arranged in a line at equal intervals along a direction inclined by an angle θ with respect to the Y-axis direction (hereinafter referred to as “T direction” for convenience). The light emitting part rows composed of the light emitting parts are arranged in four rows at equal intervals d1 in the X-axis direction. Further, when 40 light emitting units are orthogonally projected onto a virtual line extending in the X-axis direction, the intervals between the light emitting units are equal intervals d2. In the present specification, the “interval between the light emitting portions” refers to the distance between the centers of the two light emitting portions. The surface emitting laser array chip LA is arranged so that the Y-axis direction corresponds to the main scanning direction and the X-axis direction corresponds to the sub-scanning direction.

  The electrode pads are independently connected to the respective light emitting units on a one-to-one basis by electrode wiring (not shown).

  The electrode pad is wire-bonded with the metal wiring of the package and Au wire (not shown).

  Here, as shown in FIG. 8, each light emitting unit is formed on a substrate 101 with an n-GaAs buffer layer 102, a lower reflecting mirror 103, a lower spacer layer 104, an active layer 105, an upper spacer layer 106, selective oxidation. A semiconductor layer such as the layer 107, the upper reflecting mirror 108, and the GaAs contact layer 114 are sequentially stacked, and emits laser light having a wavelength of 780 nm. Hereinafter, a structure in which a plurality of these semiconductor layers are stacked is also referred to as a “semiconductor stacked body” for convenience.

  The substrate 101 is an n-GaAs substrate.

The lower reflecting mirror 103 is a pair of a low refractive index layer made of n-Al _0.9 Ga _0.1 As and a high refractive index layer made of n-Al _0.3 Ga _0.7 As. Have. Then, between the low refractive index layer and the high refractive index layer, a composition gradient layer having a thickness of 20 nm (illustrated) in which the composition is gradually changed from one composition to the other composition in order to reduce electrical resistance. (Omitted) is provided. Each refractive index layer includes 1/2 of the composition gradient layer, and is set to have an optical thickness of λ / 4 when the oscillation wavelength is λ.

The lower spacer layer 104 is a layer made of non-doped Al _0.6 Ga _0.4 As.

The active layer 105 is an Al _0.15 Ga _0.85 As / Al _0.6 Ga _0.4 As multiple quantum well active layer.

The upper spacer layer 106 is a layer made of non-doped Al _0.6 Ga _0.4 As.

  The portion composed of the lower spacer layer 104, the active layer 105, and the upper spacer layer 106 is also called a resonator structure, and the thickness thereof is set to be one wavelength optical thickness. The active layer 105 is provided at the center of the resonator structure at a position corresponding to the antinode of the standing wave distribution of the electric field so as to obtain a high stimulated emission probability.

The upper reflecting mirror 108 has 26 pairs of a low refractive index layer made of p-Al _0.9 Ga _0.1 As and a high refractive index layer made of p-Al _0.3 Ga _0.7 As as a pair. ing. Then, between the low refractive index layer and the high refractive index layer, a composition gradient layer having a thickness of 20 nm (illustrated) in which the composition is gradually changed from one composition to the other composition in order to reduce electrical resistance. (Omitted) is provided. Each refractive index layer includes 1/2 of the composition gradient layer, and is set to have an optical thickness of λ / 4 when the oscillation wavelength is λ.

  A selective oxidation layer 107 made of p-AlAs is provided at a position away from the resonator structure in the upper reflecting mirror 108 by λ / 4.

  Next, a method for manufacturing the surface emitting laser array chip LA will be briefly described.

(1) The semiconductor stacked body is formed by crystal growth using metal organic chemical vapor deposition (MOCVD) or molecular beam crystal growth (MBE).

Here, trimethylaluminum (TMA), trimethylgallium (TMG), and trimethylindium (TMI) are used as the Group III material, and arsine (AsH ₃ ) gas is used as the Group V material. Further, carbon tetrabromide (CBr ₄ ) is used as a p-type dopant material, and hydrogen selenide (H ₂ Se) is used as an n-type dopant material.

(2) A photomask including a photomask corresponding to the light emitting portion is patterned on the surface of the stacked body, which is the surface (surface opposite to the substrate 1) in the semiconductor stacked body, by a photolithography method. Here, the shape of the photomask corresponding to the light emitting portion is a square shape having a side of 20 μm.

(3) A mesa shape is formed by dry etching using a photomask as an etching mask. Hereinafter, for convenience, a mesa-shaped portion (structure) is abbreviated as “mesa”. Here, the etching is performed until the bottom surface of the etching reaches the lower reflecting mirror 103.

(4) The photomask is removed.

(5) The semiconductor stacked body is heat-treated in water vapor to selectively oxidize the selectively oxidized layer 108 in the mesa. Then, an unoxidized region in the selective oxidation layer 108 remains in the central portion of the mesa. As a result, a so-called current confinement structure is formed in which the path of the drive current of the light emitting unit is limited to only the central part of the mesa. Here, the non-oxidized region (current passing region) has a square shape with a side length of 4 μm.

(6) An insulating film 109 made of SiO ₂ is formed as a passivation film by using a vapor phase chemical deposition method (CVD method).

(7) Flatten with polyimide 110.

(8) Open the window of the P-side electrode contact on the top of the mesa. Here, after masking with a photoresist, the opening at the top of the mesa is exposed to remove the photoresist at that portion, and then the polyimide 110 and the insulating film 109 are etched and opened with BHF.

(9) A square resist pattern having a side of 10 μm is formed in a region to be a light emitting portion on the upper part of the mesa. Then, a p-side electrode material is deposited. As the electrode material on the p side, a multilayer film made of Cr / AuZn / Au or a multilayer film made of Ti / Pt / Au is used.

(10) The electrode material of the light emitting part is lifted off, and the p-side electrode 111 is formed.

(11) After polishing the back side of the substrate 101 to a predetermined thickness (for example, about 100 μm), the n-side electrode 112 is formed. Here, the n-side electrode 112 is a multilayer film made of AuGe / Ni / Au.

(12) Ohmic conduction is established between the p-side electrode 111 and the n-side electrode 112 by annealing. Thereby, each mesa becomes a light emission part, respectively.

(13) The semiconductor laminate is cut for each chip.

Returning to Figure 3, the optical module 10B is configured first portion 10B ₁ and the second portion 10B _2. The first portion 10B ₁ includes a half mirror 10c, the condenser lens 10f, and the light receiving element 10g. The second portion 10B ₂ has a collimator lens 10d and aperture plate 10e,.

The first portion 10B ₁ is a + Z side of semiconductor laser module 10A, a half mirror 10c on the optical path of the light emitted from the surface emitting laser array chip LA is arranged to be positioned. A part of the light incident on the half mirror 10c is reflected in the −Y direction and is received by the light receiving element 10g through the condenser lens 10f. The light receiving element 10g outputs a signal (photoelectric conversion signal) corresponding to the amount of received light to the laser control device.

The second portion 10B ₂ is a first portion 10B ₁ of the + Z side, a collimator lens 10d on the optical path of the light transmitted through the half mirror 10c is arranged so as to be located. The collimating lens 10d makes light transmitted through the half mirror 10c substantially parallel light. The aperture plate 10e has an aperture and shapes the light that has passed through the collimating lens 10d. The light that has passed through the opening of the opening plate 10 e becomes the output of the light source unit 10.

  As described above, the light emitted from the surface emitting laser array chip LA is directly incident on the optical module 10B.

  Returning to FIG. 2, the cylindrical lens 13 condenses the light output from the light source unit 10 in the vicinity of the deflection reflection surface of the polygon mirror 14 via the mirror 17.

  The polygon mirror 14 is formed of a regular hexagonal columnar member having a low height, and six deflection reflection surfaces are formed on the side surface. Then, it is rotated at a constant angular velocity in the direction of the arrow shown in FIG. 2 by a rotation mechanism (not shown). Therefore, the light emitted from the light source unit 10 and condensed near the deflection reflection surface of the polygon mirror 14 by the cylindrical lens 13 is deflected at a constant angular velocity by the rotation of the polygon mirror 14.

  The fθ lens 15 has an image height proportional to the incident angle of light from the polygon mirror 14, and moves the image plane of light deflected by the polygon mirror 14 at a constant angular velocity at a constant speed in the main scanning direction.

  The toroidal lens 16 forms an image of the light from the fθ lens 15 on the surface of the photosensitive drum 1030 via the mirror 18.

  In the surface emitting laser array chip LA, since the intervals between the light emitting portions when the respective light emitting portions are orthogonally projected onto the virtual line extending in the X-axis direction are equal intervals d2, the lighting timing is adjusted as shown in FIG. As a result, it can be understood that the configuration is similar to the case where the light sources are arranged at equal intervals in the sub-scanning direction on the photosensitive drum 1030. For example, if the distance d1 is 26.5 μm, the distance d2 is 2.65 μm. If the magnification of the optical system is doubled, writing dots can be formed on the photosensitive drum 1030 at intervals of 5.3 μm in the sub-scanning direction. This corresponds to 4800 dpi (dots / inch). That is, high-density writing of 4800 dpi (dot / inch) can be performed. Of course, the density can be increased by increasing the number of light emitting portions in the T direction, making the array arrangement in which the distance d1 is narrowed and the distance d2 is further reduced, or by reducing the magnification of the optical system. Printing is possible. Note that the writing interval in the main scanning direction can be easily controlled by the lighting timing of the light source.

  In this case, the laser printer 1000 can perform printing without decreasing the printing speed even if the writing dot density increases. Further, when the writing dot density is the same, the printing speed can be further increased.

  As described above, according to the light source unit 10 according to the present embodiment, the light source unit 10 includes the semiconductor laser module 10A including the semiconductor laser 10a, the half mirror 10c, the light receiving element 10g, the collimating lens 10d, and the aperture plate 10e. It has an optical module 10B. The light emitted from the surface emitting laser array chip LA of the semiconductor laser 10a enters the half mirror 10c only through the air layer, and the light transmitted through the half mirror 10c passes through the collimating lens 10d and the aperture plate 10e. 10 is output.

  In a light source unit using a conventional sealing glass, it is difficult to obtain a light transmittance of nearly 100% even when an antireflection film is coated, and the light utilization efficiency is reduced due to reflection loss. In particular, since a surface emitting laser is difficult to obtain a high output in a single mode like an edge emitting laser, it is necessary to reduce loss in the optical system as much as possible. In the present embodiment, light emitted from the surface emitting laser array chip LA is directly incident on the optical module 10B without using a sealing glass material or the like, so that it is possible to suppress a decrease in light utilization efficiency. is there.

  Further, in the present embodiment, since there is no sealing glass material, light reflected by the sealing glass does not enter the surface emitting laser array chip LA unlike a light source unit using a conventional sealing glass. . A part of the light incident on the collimating lens 10d is scattered on the incident surface of the collimating lens 10d. However, since the incident surface is a curved surface, the light is scattered in a direction different from the direction toward the surface emitting laser array chip LA. The Therefore, the scattered light on the incident surface of the collimator lens 10d does not enter the surface emitting laser array chip LA. Therefore, there is no influence of return light to the surface emitting laser array chip LA, and stable laser light can be obtained.

Further, according to the present embodiment, since the peripheral portion of the surface emitting laser array chip LA is covered with the optical module (precisely, the first portion 10B ₁ ), dust or the like adheres to the surface emitting laser array chip LA. Can be prevented.

According to the present embodiment, the position adjustment and assembly is in the surface of the substrate, a first portion 10B _1, to adjust the relative position with respect to the second substrate portion 10B _2, easily carried out by a screw be able to. Therefore, the position adjustment process such as tilt angle adjustment can be simplified, and the manufacturing cost can be reduced.

  Further, the surface emitting laser does not require cleavage and can be manufactured at low cost because the cost in the inspection process is lower than that of the edge emitting laser. The surface emitting laser array chip LA can be easily manufactured at a very low cost by photolithography.

  Moreover, since there is no sealing glass, component cost can be reduced compared with the past.

  Therefore, according to the present embodiment, it is possible to realize a light source unit excellent in laser quality and light utilization efficiency without incurring cost increase.

  In addition, according to the optical scanning device 1010 according to the present embodiment, since the light source unit having excellent laser quality and light utilization efficiency is provided without increasing the cost, the cost is not increased as a result. The optical scanning can be performed with high accuracy.

  In addition, the laser printer 1000 according to the present embodiment includes the optical scanning device 1010 that can perform optical scanning with high accuracy without incurring an increase in cost, and as a result, without incurring an increase in cost. High-quality images can be formed.

In the embodiment described above, as an example, as shown in FIGS. 10 and 11, the surface of each light emitting portion in the surface emitting laser array chip LA may be covered with a dielectric multilayer film 113. For example, in the method of manufacturing the surface emitting laser array chip LA, the semiconductor stacked body is cut by a known dielectric deposition technique such as an EB deposition method before cutting the semiconductor laminate for each chip (the step (13)). A dielectric multilayer film 113 composed of a pair of SiO ₂ film and TiO ₂ film may be deposited on the surface of the laminate. In this case, the thickness of each dielectric film is set to λ (m + 1) / 4n (n is the refractive index at the wavelength λ of each dielectric layer, m = 0, 1, 2), the same function as that of the upper reflecting mirror 108 can be added to the dielectric multilayer film 113.

In this case, since the refractive index of TiO ₂ is larger than the refractive index of SiO ₂ , the TiO ₂ film does not decrease the reflectance of the reflecting mirror composed of the upper reflecting mirror 108 and the dielectric multilayer film 113. Is preferably the surface side. In addition, the code | symbol 108a in FIG. 11 has shown the high refractive index layer of the upper reflective mirror 108. FIG.

  Thereby, the surface of the surface emitting laser array chip LA is shielded from the environmental atmosphere, and it is possible to prevent intrusion of moisture and oxidation of the surface. That is, the reliability (particularly, long-term reliability) of the surface emitting laser array chip LA can be further improved. Since the dielectric multilayer film 113 is a part of the reflecting mirror, it is not necessary to consider the return light from the dielectric multilayer film 113.

  In the above embodiment, the case of the laser printer 1000 as the image forming apparatus has been described. However, the present invention is not limited to this. In short, an image forming apparatus provided with the optical scanning device 1010 can form a high-quality image.

  For example, an image forming apparatus that includes the optical scanning device 1010 and that directly irradiates laser light onto a medium (for example, paper) that develops color with laser light may be used.

  Further, an image forming apparatus using a silver salt film as the image carrier may be used. In this case, a latent image is formed on the silver salt film by optical scanning, and this latent image can be visualized by a process equivalent to a developing process in a normal silver salt photographic process. Then, it can be transferred to photographic paper by a process equivalent to a printing process in a normal silver salt photographic process. Such an image forming apparatus can be implemented as an optical plate making apparatus or an optical drawing apparatus that draws a CT scan image or the like.

  Further, even an image forming apparatus that forms a multi-color image can form a high-definition image by using an optical scanning device that supports color images.

  For example, as shown in FIG. 12, a tandem color machine 1500 corresponding to a color image and including a plurality of photosensitive drums may be used. The tandem color machine 1500 includes a black (K) photosensitive drum K1, a charger K2, a developing unit K4, a cleaning unit K5, a transfer charging unit K6, a cyan (C) photosensitive drum C1, a charging unit. A developing unit C2, a developing unit C4, a cleaning unit C5, a transfer charging unit C6, a magenta (M) photosensitive drum M1, a charging unit M2, a developing unit M4, a cleaning unit M5, and a transfer charging unit M6; A yellow (Y) photosensitive drum Y1, a charger Y2, a developing unit Y4, a cleaning unit Y5, a transfer charging unit Y6, an optical scanning device 1010A, a transfer belt 80, a fixing unit 30 and the like are provided. .

  The optical scanning device 1010A includes a light source unit for black, a light source unit for cyan, a light source unit for magenta, and a light source unit for yellow. Each light source unit is a light source unit equivalent to the light source unit 10. The light from the light source unit for black is irradiated to the photosensitive drum K1 via the scanning optical system for black, and the light from the light source unit for cyan is irradiated to the photosensitive drum C1 via the scanning optical system for cyan. The light from the light source unit for magenta is irradiated to the photosensitive drum M1 through the scanning optical system for magenta, and the light from the light source unit for yellow is irradiated to the photosensitive member through the scanning optical system for yellow. The drum Y1 is irradiated.

  Each photosensitive drum rotates in the direction of the arrow in FIG. 12, and a charger, a developer, a transfer charging unit, and a cleaning unit are arranged in the order of rotation. Each charger uniformly charges the surface of the corresponding photosensitive drum. The surface of the photosensitive drum charged by the charger is irradiated with light by the optical scanning device 1010A, and an electrostatic latent image is formed on the photosensitive drum. Then, a toner image is formed on the surface of the photosensitive drum by the corresponding developing device. Further, the toner image of each color is transferred onto the recording paper by the corresponding transfer charging means, and finally the image is fixed on the recording paper by the fixing means 30.

  In a tandem color machine, color misregistration of each color may occur due to mechanical accuracy or the like. However, the correction accuracy of color misregistration of each color can be improved by selecting a light emitting unit to be lit.

  In the tandem color machine 1500, instead of the optical scanning device 1010A, a black optical scanning device, a cyan optical scanning device, a magenta optical scanning device, and a yellow optical scanning device may be used. In short, the light source unit of each optical scanning device may be any light source unit equivalent to the light source unit 10.

<Optical transmission system>
FIG. 13 shows a schematic configuration of an optical transmission system 2000 according to an embodiment of the present invention. In this optical transmission system 2000, an optical transmission module 2001 and an optical reception module 2005 are connected by an optical fiber cable 2004, and one-way optical communication from the optical transmission module 2001 to the optical reception module 2005 is possible.

  The optical transmission module 2001 includes a light source 2002 including a light source unit equivalent to the light source unit 10, and a drive circuit 2003 that modulates the light intensity of the laser light output from the light source 2002 in accordance with an electrical signal input from the outside. have.

  The optical signal output from the light source 2002 is coupled to the optical fiber cable 2004, guided through the optical fiber cable 2004, and input to the optical receiving module 2005.

  The optical receiving module 2005 includes a light receiving element 2006 that converts an optical signal into an electric signal, and a receiving circuit 2007 that performs signal amplification, waveform shaping, and the like on the electric signal output from the light receiving element 2006.

  According to the optical transmission module 2001 according to the present embodiment, since the light source 2002 includes a light source unit equivalent to the light source unit 10, it is possible to generate a high-quality optical signal as a result. In this case, a surface emitting laser array chip LA ′ shown in FIG. 14 may be used as an example instead of the surface emitting laser array chip LA. A microlens array may be used instead of the collimating lens.

  In addition, the optical transmission system 2000 according to the present embodiment includes the optical transmission module 2001 that can generate a high-quality optical signal, and as a result, performs high-quality optical transmission with low power consumption. Is possible.

  In the present embodiment, a configuration example of unidirectional communication of a single channel is shown, but a configuration of bidirectional communication, a parallel transmission method, a wavelength division multiplex transmission method, or the like can also be adopted. In short, the light source 2002 only needs to have a light source unit equivalent to the light source unit 10.

  As described above, the light source unit of the present invention is suitable for obtaining excellent laser quality and light utilization efficiency without incurring high costs. The optical scanning device of the present invention is suitable for performing optical scanning with high accuracy without incurring an increase in cost. The image forming apparatus of the present invention is suitable for forming a high quality image. The optical transmission module of the present invention is suitable for generating a high-quality optical signal. The optical transmission system of the present invention is suitable for performing high-quality optical transmission.

It is a figure for demonstrating schematic structure of the laser printer which concerns on one Embodiment of this invention. It is the schematic which shows the optical scanning device in FIG. It is a figure for demonstrating the light source unit in FIG. It is FIG. (1) for demonstrating the semiconductor laser of a light source unit. FIGS. 5A and 5B are views (part 2) for explaining the semiconductor laser, respectively. It is a figure for demonstrating the surface emitting laser array chip | tip of a semiconductor laser. It is the figure which expanded the element part of FIG. It is a figure for demonstrating the structure of the light emission part of a surface emitting laser array chip. It is a figure for demonstrating a writing dot. It is a figure for demonstrating the modification of the light emission part of a surface emitting laser array chip. It is a figure for demonstrating the dielectric material multilayer film of FIG. It is a figure for demonstrating schematic structure of a tandem color machine. It is a figure for demonstrating schematic structure of the optical transmission module and optical transmission system which concern on one Embodiment of this invention. It is a figure for demonstrating the modification of a surface emitting laser array chip.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Light source unit, 10A ... Semiconductor laser module, 10B ... Optical module, 10c ... Half mirror (branch optical element), 10d ... Collimating lens, 10e ... Opening plate, 10g ... Light receiving element (photodetector), 14 ... Polygon mirror (Deflector), 15 ... fθ lens (part of scanning optical system), 16 ... toroidal lens (part of scanning optical system), 108 ... upper reflecting mirror (multilayer reflecting mirror), 113 ... dielectric multilayer film (dielectric) Body layer), 1000 ... laser printer (image forming apparatus), 1010 ... optical scanning apparatus, 1010A ... optical scanning apparatus, 1030 ... photosensitive drum (image carrier), 1500 ... tandem color machine (image forming apparatus), 2000 ... Optical transmission system, 2001 ... Optical transmission module (optical transmission module), 2003 ... Drive circuit (drive device), 2004 ... Optical fiber cable (Light transmission medium), 2006 ... light receiving element (part of converter), 2007 ... receiver circuit (part of converter), LA ... surface emitting laser array chip, LA '... surface emitting laser array chip, K1, C1, M1, Y1... Photosensitive drum (image carrier).

Claims (13)

A semiconductor laser module including a semiconductor laser having at least one light emitting portion;
An optical module in contact with the semiconductor laser module, and the light emitted from the semiconductor laser is directly incident only through an air layer.   The light source unit according to claim 1, wherein the semiconductor laser is a surface emitting laser.   The light source unit according to claim 2, wherein an emission surface of the semiconductor laser is covered with a dielectric layer. The semiconductor laser has a multilayer reflector,
The light source unit according to claim 3, wherein the dielectric layer is a part of the multilayer reflecting mirror. The optical module is
A branching optical element for branching a part of the light emitted from the semiconductor laser;
The light source unit according to claim 1, further comprising: a photodetector that receives light branched by the branch optical element. The optical module is
The light source unit according to claim 1, further comprising a collimating lens that makes light emitted from the semiconductor laser substantially parallel light. The optical module is
The light source unit according to claim 1, further comprising an aperture plate that shapes light emitted from the semiconductor laser. The semiconductor laser has a plurality of light emitting units,
The light source unit according to claim 1, wherein the optical module has a microlens array. An optical scanning device that scans a surface to be scanned with light,
A light source unit according to any one of claims 1 to 8;
A deflector for deflecting light from the light source unit;
A scanning optical system for condensing the light deflected by the polarizer on the surface to be scanned. At least one image carrier;
An image forming apparatus comprising: at least one optical scanning device according to claim 9 that scans the at least one image carrier with light including image information.   The image forming apparatus according to claim 10, wherein the image information is color image information. An optical transmission module that generates an optical signal according to an input electrical signal,
A light source unit according to any one of claims 1 to 8;
An optical transmission module comprising: a driving device that drives the semiconductor laser of the light source unit according to the input electric signal. An optical transmission module according to claim 12;
An optical transmission medium for transmitting an optical signal generated by the optical transmission module;
A converter for converting an optical signal through the optical transmission medium into an electric signal;