JP2008192780A - Surface-emission laser module, optical scanner, device for forming image, optical transmission module and optical transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably output a plurality of lights with a high density without increasing a cost. <P>SOLUTION: A package is sealed on the optical paths of a plurality of lights emitted from a surface-emission laser array element 23 while a cover glass 21 reflecting a part of an incident light and making the remainder transmit is arranged. A space between the light from a fifth light-emitting section row L5 and the light from a sixth light-emitting section row L6 is reduced and both lights are made to transmit in the Y-axis direction with respect to the light from the fifth light-emitting section row L5 and the light from the sixth light-emitting section row L6 while the light from the fifth light-emitting section row L5 and the light from the sixth light-emitting section row L6 are reflected in the direction different from the return direction to a light-emitting section. Accordingly, the deterioration of the light-emitting characteristics of the light-emitting section by heat generation can be suppressed without lowering a writing-dot density. Noise by a reflected light can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface emitting laser module, an optical scanning device, an image forming apparatus, an optical transmission module, and an optical transmission system. More specifically, the present invention relates to a surface emitting laser module capable of outputting a plurality of lights, and an optical light having the surface emitting laser module. The present invention relates to a scanning device, an image forming apparatus including the optical scanning device, an optical transmission module including the surface emitting laser module, and an optical transmission system including the optical transmission module.

  In electrophotographic image recording, an image forming apparatus using a laser is widely used. In this case, the image forming apparatus includes an optical scanning device, and forms a latent image by rotating the drum while scanning laser light using a polygon scanner (for example, a polygon mirror) in the axial direction of the photosensitive drum. Is common. In the field of electrophotography, an image forming apparatus is required to increase image density in order to improve image quality and to increase image output speed in order to improve operability.

  As a method for achieving both high density and high speed, there is a method of making multi-beams of light emitted from a light source. As a multi-beam light source, a surface emitting laser array in which a plurality of surface emitting lasers (VCSEL) are arrayed is used. Was considered.

  Since this surface emitting laser array has characteristics that are reduced by heat generation and its life is shortened, various proposals for suppressing heat generation have been made.

  In Patent Document 1, a lower reflector layer structure and an upper reflector layer structure are formed in this order on a semiconductor substrate, and an active layer and a current confinement layer are interposed between each reflector layer structure. The area from the layer structure to the lower layer to at least the lower end surface of the current confinement layer is a columnar mesa, and the area of the upper end surface of the mesa is larger than the mesa cross-sectional area in the vicinity of the current confinement layer. A type semiconductor laser array is disclosed.

  In Patent Document 2, a hetero spike buffer layer having an intermediate valence band energy is provided between semiconductor layers having different band gap energies constituting the semiconductor distributed Bragg reflector, and the hetero spike buffer layer has a valence band energy. Is composed of a continuous or stepwise composition graded layer or a combination of these, and a region with a large change rate of valence band energy is placed on the side in contact with the layer with large band gap energy on the side in contact with the layer with small band gap energy. A surface emitting semiconductor laser array having a region with a small change rate of valence band energy is disclosed.

  By the way, in a semiconductor laser, noise may be generated by return light.

  Therefore, Patent Document 3 discloses a surface emitting laser in which an opening for extracting light emission is provided at a position shifted from a position facing the light emitting region of the p-side electrode.

JP 2001-85788 A JP 2002-359433 A JP 2005-347715 A

  However, in the semiconductor laser arrays disclosed in Patent Document 1 and Patent Document 2, the element structure becomes complicated, making it difficult, and increasing the cost.

  Further, in the surface emitting laser disclosed in Patent Document 3, since the 0th-order transverse mode is suppressed and the light in the higher-order transverse mode is used, it is used as a light source for an imaging optical system such as an optical scanning device. Cannot be used.

  The present invention has been made under such circumstances, and a first object thereof is to provide a surface emitting laser module capable of stably outputting a plurality of lights at a high density without causing an increase in cost. There is to do.

  A second object of the present invention is to provide an optical scanning device capable of stably performing high-density scanning without incurring an increase in cost.

  A third object of the present invention is to provide an image forming apparatus capable of stably forming a high quality image at high speed without incurring an increase in cost.

  A fourth object of the present invention is to provide an optical transmission module that can stably generate 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 stably performing high-quality optical transmission without incurring an increase in cost.

  According to a first aspect of the present invention, a surface emitting laser array element having a plurality of light emitting portions; a package on which the surface emitting laser array element is mounted; and a plurality of lights emitted from the surface emitting laser array element And a transparent member that reflects part of incident light and transmits the rest, wherein the plurality of light emitting parts include a first light emitting part and a second light emitting part, and the transparent The member includes the light from the first light emitting unit and the second light with respect to at least one direction orthogonal to the traveling direction of the light from the first light emitting unit and the light from the second light emitting unit. The surface-emitting laser module is characterized in that the distance from the light emitting unit is reduced and transmitted, and reflected in a direction different from the direction returning to the light emitting unit.

  According to this, most of the light from the first light-emitting unit and the light from the second light-emitting unit are transmitted at a small interval with respect to at least one direction orthogonal to the traveling direction of the light and transmitted through the transparent member. . Further, part of the light from the first light emitting unit and the light from the second light emitting unit is reflected by the transparent member, but is reflected in a direction different from the direction toward one of the plurality of light emitting units. In this case, the interval between the first light emitting unit and the second light emitting unit can be widened, and a decrease in the light emission characteristics of the light emitting unit due to heat generation can be suppressed. Further, since reflected light does not return to the light emitting portion, noise can be reduced. Therefore, an inexpensive material can be used as the transparent member, and as a result, a plurality of lights can be stably output at high density without increasing the cost.

  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 having the surface emitting laser module of the present invention; and deflection for deflecting light from the light source unit And a scanning optical system for condensing the light deflected by the polarizer onto the surface to be scanned.

  According to this, since the light source unit has the surface emitting laser module of the present invention, as a result, high-density scanning can be stably performed 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 stably form a high-quality image at a high speed 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 surface emitting laser module of the present invention; and the surface emitting laser array of the surface emitting laser module. And a driving device that drives the element in accordance with the input electric signal.

  According to this, since the surface emitting laser module of the present invention is provided, as a result, it is possible to stably generate a high-quality optical signal without increasing the cost.

  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 stably 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 laser printer 500 according to an embodiment of the present invention.

  The laser printer 500 includes an optical scanning device 900, a photosensitive drum 901, a charging charger 902, a developing roller 903, a toner cartridge 904, a cleaning blade 905, a paper feeding tray 906, a paper feeding roller 907, a registration roller pair 908, and a transfer charger 911. , A static elimination unit 914, a fixing roller 909, a paper discharge roller 912, a paper discharge tray 910, and the like.

  A photosensitive layer is formed on the surface of the photosensitive drum 901. That is, the surface of the photoconductive drum 901 is the surface to be scanned. Here, the photosensitive drum 901 rotates in the direction of the arrow in FIG.

  The charging charger 902, the developing roller 903, the transfer charger 911, the charge removal unit 914, and the cleaning blade 905 are each disposed near the surface of the photosensitive drum 901. Then, with respect to the rotation direction of the photosensitive drum 901, the charging charger 902, the developing roller 903, the transfer charger 911, the static elimination unit 914, and the cleaning blade 905 are arranged in this order.

  The charging charger 902 uniformly charges the surface of the photosensitive drum 901.

  The optical scanning device 900 irradiates the surface of the photosensitive drum 901 charged by the charging charger 902 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 901 on the surface of the photosensitive drum 901. The latent image formed here moves in the direction of the developing roller 903 as the photosensitive drum 901 rotates. The configuration of the optical scanning device 900 will be described later.

  The toner cartridge 904 stores toner, and the toner is supplied to the developing roller 903.

  The developing roller 903 causes the toner supplied from the toner cartridge 904 to adhere to the latent image formed on the surface of the photosensitive drum 901 to visualize the image information. Here, the latent image to which the toner is attached (hereinafter also referred to as “toner image” for convenience) moves in the direction of the transfer charger 911 as the photosensitive drum 901 rotates.

  Recording paper 913 is stored in the paper feed tray 906. A paper feed roller 907 is disposed in the vicinity of the paper feed tray 906, and the paper feed roller 907 takes out the recording paper 913 one by one from the paper feed tray 906 and conveys it to the registration roller pair 908. The registration roller pair 908 is disposed in the vicinity of the transfer roller 911, temporarily holds the recording paper 913 taken out by the paper feed roller 907, and the recording paper 913 is synchronized with the rotation of the photosensitive drum 901. It is sent out toward the gap between 901 and the transfer charger 911.

  A voltage having a polarity opposite to that of the toner is applied to the transfer charger 911 in order to electrically attract the toner on the surface of the photosensitive drum 901 to the recording paper 913. With this voltage, the toner image on the surface of the photosensitive drum 901 is transferred to the recording paper 913. The recording sheet 913 transferred here is sent to the fixing roller 909.

  In the fixing roller 909, heat and pressure are applied to the recording paper 913, whereby the toner is fixed on the recording paper 913. The recording paper 913 fixed here is sent to the paper discharge tray 910 via the paper discharge roller 912 and sequentially stacked on the paper discharge tray 910.

  The neutralization unit 914 neutralizes the surface of the photosensitive drum 901.

  The cleaning blade 905 removes toner remaining on the surface of the photosensitive drum 901 (residual toner). The removed residual toner is used again. The surface of the photosensitive drum 901 from which the residual toner has been removed returns to the position of the charging charger 902 again.

  Next, the configuration of the optical scanning device 900 will be described.

  As shown in FIG. 2, the optical scanning device 900 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 shown in FIG. 3 and FIG. 4 as an example, the light source unit 10 includes a surface emitting laser array element 23 having a plurality of light emitting portions, a package 25 on which the surface emitting laser array element 23 is mounted, and a surface emitting It has a surface emitting laser module 20 that is disposed on the optical path of a plurality of lights from the laser array element 23 and includes a cover glass 21 that seals the package 25. In the present specification, the laser oscillation direction in the surface emitting laser array element 23 is described as a Z-axis direction, and two directions perpendicular to each other in a plane perpendicular to the Z-axis direction are described as an X-axis direction and a Y-axis direction.

  As an example, the surface emitting laser array element 23 includes 40 light emitting units 231 as shown in FIG. Here, the Y-axis direction is a direction corresponding to the main scanning direction, and the X-axis direction is a direction corresponding to the sub-scanning direction.

  For example, as shown in FIG. 6, the 40 light emitting units 231 are divided into a first array 23 a composed of 20 light emitting units 231 and a second array 23 b composed of 20 light emitting units 231.

  In the first array 23a, as shown in FIG. 7 as an example, a direction in which 20 light emitting portions 231 form an inclination angle α from the Y-axis direction toward the X-axis direction (hereinafter referred to as “T direction” for convenience). ) And the X-axis direction.

  The intervals between the light emitting portions in the Y axis direction are equal intervals dm1, and the intervals between the light emitting portions in the X axis direction are equal intervals ds2. In the present specification, the “interval between the light emitting portions” refers to the distance between the centers of the two light emitting portions. Further, when 20 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 ds1.

  In the following, for convenience, as shown in FIG. 7, the first light emitting unit row L1, the first light emitting unit row L1 including the four light emitting units arranged closest to the −Y side in the first array 23a. The light emitting unit row composed of four light emitting units arranged on the + Y side of the light emitting unit row L1 is the second light emitting unit row L2, and the four light emitting units arranged on the + Y side of the second light emitting unit row L2. The third light emitting part row L3 is a light emitting part row consisting of four parts, and the fourth light emitting part row L4 is a light emitting part row consisting of four light emitting parts arranged on the + Y side of the third light emitting part row L3. A light emitting part row formed of four light emitting parts arranged on the + Y side of the fourth light emitting part row L4 is referred to as a fifth light emitting part row L5.

  In the second array 23b, as shown in FIG. 8 as an example, 20 light emitting units 231 are two-dimensionally arranged along the T direction and the X axis direction, respectively.

  The intervals between the light emitting portions in the Y axis direction are equal intervals dm1, and the intervals between the light emitting portions in the X axis direction are equal intervals ds2. Further, when 20 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 ds1.

  In the following, for convenience, as shown in FIG. 8, a light emitting unit row composed of four light emitting units arranged on the most −Y side in the second array 23 b is referred to as a sixth light emitting unit row L 6, the sixth light emitting unit row L 6. The light emitting part row composed of four light emitting parts arranged on the + Y side of the light emitting part row L6 is the seventh light emitting part row L7, and the four light emitting elements arranged on the + Y side of the seventh light emitting part row L7. The light emitting section row consisting of four light emitting sections arranged on the + Y side of the eighth light emitting section row L8 is referred to as the ninth light emitting section row L9. A light emitting part row formed of four light emitting parts arranged on the + Y side of the ninth light emitting part row L9 is referred to as a tenth light emitting part row L10.

  As an example, as shown in FIGS. 9 and 10, the interval between the fifth light emitting unit row L5 and the sixth light emitting unit row L6 in the Y-axis direction is dm2 (> dm1), and the first array The first array 23a and the second array 23a and the 20 light emitting units of the second array 23a are orthogonally projected onto the imaginary line extending in the X-axis direction so that the interval between the light emitting units is equal to ds1. The second array 23b is arranged.

  That is, with respect to the Y-axis direction, only the interval between the fifth light emitting unit row L5 and the sixth light emitting unit row L6 is wider than the interval between other adjacent light emitting unit rows.

  Each of the light emitting portions is a 780 nm band VCSEL. As shown in FIG. 11, as an example, on the n-GaAs substrate 111, a lower reflector 112, a spacer layer 113, an active layer 114, a spacer layer 115, an upper portion A semiconductor layer such as a reflecting mirror 117 and a p-contact layer 118 is sequentially stacked. Hereinafter, a structure in which a plurality of these semiconductor layers are stacked is also referred to as a “stacked body” for convenience.

The lower reflecting mirror 112 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. Each refractive index layer is set to have an optical thickness of λ / 4 when the oscillation wavelength is λ. A composition gradient layer (not shown) in which the composition is gradually changed from one composition to the other composition is provided between the low refractive index layer and the high refractive index layer in order to reduce electrical resistance. It has been.

The spacer layer 113 is a layer made of Al _0.6 Ga _0.4 As.

The active layer 114 has a quantum well layer made of Al _0.12 Ga _0.88 As and a barrier layer made of Al _0.3 Ga _0.7 As.

The spacer layer 115 is a layer made of Al _0.6 Ga _0.4 As.

  A portion composed of the spacer layer 113, the active layer 114, and the spacer layer 115 is also called a resonator structure, and the thickness thereof is set to be one wavelength optical thickness.

The upper reflecting mirror 117 includes 24 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. ing. Each refractive index layer is set to have an optical thickness of λ / 4. A composition gradient layer (not shown) in which the composition is gradually changed from one composition to the other composition is provided between the low refractive index layer and the high refractive index layer in order to reduce electrical resistance. It has been.

  A selective oxidation layer 116 made of AlAs is provided at a position away from the resonator structure in the upper reflecting mirror 117 by λ / 4.

  Next, a method for manufacturing the surface emitting laser array element 23 will be briefly described.

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

(2) Grooves are formed by dry etching around each of a plurality of regions, each of which serves as a light emitting portion, to form a so-called mesa. Here, the bottom surface of the etching is set so as to reach the lower reflecting mirror 112. Note that the bottom surface of the etching may be at least beyond the selective oxidation layer 116. As a result, the selectively oxidized layer 116 appears on the sidewall of the trench.

(3) The laminated body in which the groove is formed is heat-treated in water vapor, and the selective oxidation layer 116 in the mesa is selectively oxidized. Then, an unoxidized region in the selective oxidation layer 116 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.

(4) Except the region where the upper electrode 103 of each mesa is formed and the light emitting portion 102, for example, a 150 nm thick SiO ₂ protective layer 120 is provided, and polyimide 119 is buried in each groove and planarized.

(5) The upper electrode 103 is formed in each mesa portion on the p contact layer 118 except for the light emitting portion 102, and each bonding pad (not shown) is formed around the laminated body. And each wiring (not shown) which connects each upper electrode 103 and the bonding pad corresponding to each is formed.

(6) A lower electrode (n-side common electrode) 110 is formed on the back surface of the laminate.

(7) The laminate is cut into a plurality of chips.

  Returning to FIG. 4, the cover glass 21 has a portion whose YZ sectional shape is V-shaped (hereinafter also referred to as “V-shaped portion” for convenience). A plurality of lights emitted from the surface emitting laser array element 23 are output from the surface emitting laser module 20 through the V-shaped portion of the cover glass 21. In addition, this cover glass 21 has neither a convergence effect nor a divergence action with respect to incident light.

  As shown in FIG. 12 as an example, the surface emitting laser array element 23 has a substantially intermediate position between the first array 23a and the second array 23b facing the bottom of the V-shaped portion of the cover glass 21 in the Y-axis direction. Placed in position.

  Here, as shown in FIG. 13 as an example, when θ of the angle of the V-shaped portion of the cover glass 21 is θ, the incident angle ψ1 of the light emitted from the light emitting portion 231 to the cover glass 21 is It is shown by the following equation (1).

  The refractive index of the cover glass 21 is n2, and the refractive index of the medium (usually using an inert gas such as air or nitrogen and the refractive index is 1.0) filling the space between the surface emitting laser array element 23 and the cover glass 21 is n1. Then, the relationship between the incident angle ψ1 on the cover glass 21 and the refraction angle ψ2 of the light incident on the cover glass 21 is expressed by the following equation (2).

  When the thickness of the cover glass 21 is t, the optical path length L of the light in the cover glass 21 is expressed by the following equation (3).

  As a result, the shift amount ΔYout of the light transmitted through the cover glass 21 is expressed by the following equation (4).

  Then, regarding the Y-axis direction, if the position of the light emitting unit 231 when the bottom of the V-shaped part is used as a reference is Yv, the transmitted light position Yout is expressed by the following equation (5).

  Further, if the distance between the surface emitting laser array element 23 and the cover glass 21 is h, the position where the light reflected by the cover glass 21 irradiates the surface emitting laser array element 23 (difference from the position of the light emitting unit 231) ΔYr is Is expressed by the following equation (6).

  For example, when θ = 85 °, n2 = 1.51 (for example, BK7), t = 500 μm, h = 500 μm, and the inside of the package is filled with nitrogen gas (n1 = 1.00), the interval of transmitted light is 2 Yout = In order to set the thickness to 30 μm, the position Yv of the light emitting portion 231 may be set to 29.8 μm. At this time, the interval between the light emitting portions is 2 · Yv = 59.6 μm, which is approximately doubled. ΔYr is 88.6 μm, and the reflected light does not return to the light emitting unit.

  For example, if θ = 80 ° and the other conditions are the same, Yv = 44.8 μm, and the interval between the light emitting portions is 2 · Yv = 89.6 μm, which is approximately tripled. ΔYr is 184.9 μm. Also in this case, the reflected light does not return to the light emitting unit.

  That is, as shown in FIG. 14 as an example, even if the interval d2 between the light emitting portions is wider than the interval d1 between the light emitting portions, the plurality of lights output through the cover glass 21 are in the Y-axis direction and the like. It becomes an interval. That is, the distance between the fifth light emitting part and the sixth light emitting part in the Y-axis direction can be made wider than before, and deterioration of characteristics due to heat generation can be suppressed.

  As an example, as shown in FIG. 14, a plurality of reflected lights RB emitted from the surface emitting laser array element 23 and reflected by the surface of the cover glass 21 are all directed in a direction different from the direction returning to the light emitting unit. Is set.

  Returning to FIG. 2, the coupling lens 11 shapes the light emitted from the light source unit 10 into substantially parallel light.

  The aperture plate 12 has an aperture and defines the beam diameter of light that passes through the coupling lens 11.

  The cylindrical lens 13 condenses the light that has passed through the opening of the aperture plate 12 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 901 via the mirror 18.

  In this case, in the surface emitting laser array element 23, since the intervals between the light emitting portions when the respective light emitting portions are orthogonally projected onto a virtual line extending in the X-axis direction are equal intervals ds1, as an example, as shown in FIG. By adjusting the lighting timing, it can be considered that the light source is arranged on the photosensitive drum 901 at equal intervals in the sub-scanning direction. For example, if the distance ds2 is 26.5 μm, the distance ds1 is 2.65 μm. If the magnification of the optical system is doubled, writing dots can be formed on the photosensitive drum 901 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, higher density and higher quality can be achieved by increasing the number of light emitting parts in the Y-axis direction, reducing the distance ds2 to reduce the distance ds1, or reducing the magnification of the optical system. Printing becomes 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 500 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 surface emitting laser module 20 according to the present embodiment, the surface emitting laser array element 23 having 40 light emitting units, the package 25 on which the surface emitting laser array element 23 is mounted, and the surface emitting. A cover glass 21 is disposed on the optical path of a plurality of lights emitted from the laser array element 23, seals the package 25, reflects a part of the incident light, and transmits the rest. The distance dm2 between the light from the fifth light emitting part row L5 and the light from the sixth light emitting part row L6 incident on the cover glass 21 in the Y-axis direction is the fifth light emitting part that has passed through the cover glass 21. The distance dm1 between the light from the row L5 and the light from the sixth light emitting portion row L6 is larger.

  As a result, the interval between the fifth light-emitting portion row L5 and the sixth light-emitting portion row L6 can be made wider than in the conventional case with respect to the Y-axis direction, so that the light-emitting portion due to heat generation without reducing the writing dot density. The deterioration of the light emission characteristics can be suppressed.

  The plurality of reflected lights emitted from the surface emitting laser array element 23 and reflected by the surface of the cover glass 21 are all directed in a direction different from the direction returning to the light emitting unit. Thereby, the noise by reflected light can be reduced.

  Therefore, it is possible to stably output a plurality of lights at a high density without increasing the cost.

  The optical scanning device 900 according to the present embodiment includes the surface emitting laser module 20 that can stably output a plurality of lights at a high density without incurring an increase in cost. Scanning at a high density can be stably performed without increasing the cost.

  Further, the laser printer 500 according to the present embodiment includes the optical scanning device 900 that can stably perform high-density scanning without incurring an increase in cost, resulting in an increase in cost. Therefore, it is possible to stably form a high quality image at a high speed without incurring.

  In addition, although the said embodiment demonstrated the case where the YZ cross-sectional shape of a cover glass included a V-shaped shape, it is not limited to this. For example, as shown in FIG. 16, the YZ cross-sectional shape of the cover glass may include an inverted trapezoidal shape, or may include an arc shape.

  Moreover, although the said embodiment demonstrated the case where a surface emitting laser array element had 40 light emission parts, it is not limited to this.

  Moreover, although the said embodiment demonstrated the case where the several light emission part of a surface emitting laser array element was arrange | positioned two-dimensionally, it is not limited to this, The several light emission part of a surface emitting laser array element May be arranged one-dimensionally.

  Moreover, although the said embodiment demonstrated the case where each light emission part of the surface emitting laser array element was VCSEL of a 780 nm band, it is not limited to this.

  Moreover, in the said embodiment, it may replace with the said cover glass 21, and may use the transparent member which has an effect | action equivalent to the cover glass 21. FIG.

  Moreover, in the said embodiment, although the said cover glass 21 has the effect | action which seals the package 25, you may provide the sealing member which seals the package 25 separately from the said cover glass 21. FIG.

  In the above-described embodiment, at least two lights included in the plurality of lights emitted from the surface emitting laser array element are related to one direction orthogonal to the traveling direction of the plurality of lights emitted from the surface emitting laser array element. The case where the interval is narrowed by passing through the cover glass has been described. However, the present invention is not limited to this, and the surface emitting laser array is not limited to two directions orthogonal to the traveling directions of a plurality of lights emitted from the surface emitting laser array element. An interval between at least two lights included in the plurality of lights emitted from the element may be narrowed by passing through the cover glass. In this case, for example, as in the main scanning direction and the sub-scanning direction, two directions orthogonal to the traveling directions of the plurality of lights emitted from the surface emitting laser array elements may be orthogonal to each other.

  In the above embodiment, the laser printer 500 is described as the image forming apparatus. However, the present invention is not limited to this. In short, the image forming apparatus including the optical scanning device 900 can stably form a high-quality image at a high speed without resulting in an increase in cost.

  Further, even an image forming apparatus that forms a color image has the surface emitting laser module 20 and uses an optical scanning device corresponding to a color image, so that high-quality color can be achieved without incurring high costs. An image can be stably formed at high speed.

  For example, as shown in FIG. 17, a tandem color machine including a plurality of photosensitive drums may be used. The tandem color machine includes a black (K) photosensitive drum K1, a charger K2, a developing device K4, a cleaning unit K5, a transfer charging unit K6, a cyan (C) photosensitive drum C1, and a charger. C2, developing unit C4, cleaning unit C5, transfer charging unit C6, magenta (M) photosensitive drum M1, charging unit M2, developing unit M4, cleaning unit M5, transfer charging unit M6, yellow (Y) photosensitive drum Y1, charging unit Y2, developing unit Y4, cleaning unit Y5, transfer charging unit Y6, optical scanning device 900, transfer belt 80, fixing unit 30 and the like.

  In this case, in the optical scanning device 900, the plurality of light emitting portions in the surface emitting laser array element 23 are divided into black, cyan, magenta, and yellow. The light from each black light emitting unit is irradiated to the photosensitive drum K1 through the black scanning optical system, and the light from each cyan light emitting unit is passed through the cyan scanning optical system. The light emitted from each light emitting unit for magenta is irradiated to the photosensitive drum M1 through the scanning optical system for magenta, and the light from each light emitting unit for yellow passes through the scanning optical system for yellow. Through the photosensitive drum Y1. The optical scanning device 900 may include the surface emitting laser module 20 for each color. Further, an optical scanning device 900 may be provided for each color.

  Each photosensitive drum rotates in the direction of the arrow in FIG. 17, 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 a beam by the optical scanning device 900, 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 images of the respective colors are 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, since the optical scanning device 900 has a two-dimensional array of high-density light emitting units, it is necessary to select a light emitting unit to be lit. Thus, the correction accuracy of the color misregistration of each color can be improved.

  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, an image forming apparatus using a color developing medium (positive photographic paper) that develops color by the heat energy of a beam spot as an image carrier may be used. In this case, a visible image can be directly formed on the image carrier by optical scanning.

<Optical transmission system>
FIG. 18 shows a schematic configuration of an optical transmission system 1000 according to an embodiment of the present invention. In this optical transmission system 1000, an optical transmission module 1001 and an optical reception module 1005 are connected by an optical fiber cable 1004, and one-way optical communication from the optical transmission module 1001 to the optical reception module 1005 is possible.

  The optical transmission module 1001 includes a light source 1002 including the surface emitting laser module 20 and a drive circuit 1003 that modulates the light intensity of the laser light output from the light source 1002 in accordance with an electric signal input from the outside. ing.

  The optical signal output from the light source 1002 is coupled to the optical fiber cable 1004, guided through the optical fiber cable 1004, and input to the optical receiving module 1005.

  The optical receiving module 1005 includes a light receiving element 1006 that converts an optical signal into an electric signal, and a receiving circuit 1007 that performs signal amplification, waveform shaping, and the like on the electric signal output from the light receiving element 1006.

  According to the optical transmission module 1001 according to the present embodiment, since the light source 1002 includes the surface emitting laser module 20, it is possible to stably output a plurality of lights at high density without increasing the cost. As a result, it is possible to stably generate an optical signal without increasing the cost.

  Also, the optical transmission system 1000 according to the present embodiment includes the optical transmission module 1001 that can stably generate an optical signal without incurring an increase in cost, resulting in an increase in cost as a result. Therefore, it is possible to stably perform large-capacity optical transmission with low power consumption.

  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 1002 only needs to include the surface emitting laser module 20.

  As described above, the surface-emitting laser module according to the present invention is suitable for stably outputting a plurality of lights at a high density without increasing the cost. Moreover, the optical scanning device of the present invention is suitable for stably performing high-density scanning without incurring an increase in cost. The image forming apparatus of the present invention is suitable for stably forming a high-quality image at high speed without incurring an increase in cost. The optical transmission module of the present invention is suitable for stably generating an optical signal without incurring an increase in cost. Moreover, the optical transmission system of the present invention is suitable for performing optical transmission stably without increasing the cost.

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 surface emitting laser module contained in the light source unit in FIG. FIG. 4 is a YZ sectional view of FIG. 3. It is a figure for demonstrating the surface emitting laser array element in a surface emitting laser module. It is FIG. (1) for demonstrating the arrangement | sequence of the several light emission part in a surface emitting laser array element. It is FIG. (2) for demonstrating the arrangement | sequence of the several light emission part in a surface emitting laser array element. It is FIG. (3) for demonstrating the arrangement | sequence of the several light emission part in a surface emitting laser array element. It is FIG. (4) for demonstrating the arrangement | sequence of the several light emission part in a surface emitting laser array element. It is FIG. (5) for demonstrating the arrangement | sequence of the several light emission part in a surface emitting laser array element. It is a figure for demonstrating the light emission part of a surface emitting laser array element. It is a figure for demonstrating the positional relationship of the cover glass and surface emitting laser array element in a surface emitting laser module. It is a figure for demonstrating the effect | action of a cover glass (the 1). It is a figure for demonstrating the effect | action of a cover glass (the 1). It is a figure for demonstrating the write dot of a subscanning direction. It is a figure for demonstrating the modification of a cover glass. 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.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Light source unit, 14 ... Polygon mirror (deflector), 15 ... f (theta) lens (a part of scanning optical system), 16 ... Toroidal lens (a part of scanning optical system), 20 ... Surface emitting laser module, 21 ... Cover Glass, 23 ... Surface emitting laser array element, 25 ... Package, 231 ... Light emitting section, 500 ... Laser printer, 900 ... Optical scanning device, 901 ... Photosensitive drum (image carrier), 1000 ... Optical transmission system, 1001 ... Light Transmission module (light transmission module), 1003 ... Drive circuit (drive device), 1004 ... Optical fiber cable (light transmission medium), 1006 ... Light receiving element (part of converter), 1007 ... Reception circuit (part of converter) ).

Claims (16)

A surface emitting laser array element having a plurality of light emitting portions;
A package on which the surface emitting laser array element is mounted;
A transparent member disposed on an optical path of a plurality of lights emitted from the surface-emitting laser array element, reflecting a part of incident light and transmitting the rest.
The plurality of light emitting units includes a first light emitting unit and a second light emitting unit,
The transparent member includes the light from the first light-emitting unit and the light from the first light-emitting unit and the light from the second light-emitting unit with respect to at least one direction orthogonal to the traveling direction of the light and the light from the first light-emitting unit. A surface emitting laser module, wherein the distance from the light from the second light emitting portion is reduced and transmitted, and the light is reflected in a direction different from the direction returning to the light emitting portion.   The amount of decrease in the interval is calculated by using the thickness t of the transparent member, the incident angle ψ1 to the transparent member, and the refraction angle ψ2 of the light incident on the transparent member, (2t / cos ψ2) · sin (ψ1-ψ2 The surface emitting laser module according to claim 1, wherein   The surface emitting laser module according to claim 1, wherein the transparent member transmits light without changing a divergence degree.   The surface emitting laser module according to claim 3, wherein the transparent member seals the package.   The surface emitting laser module according to claim 4, wherein the transparent member is a cover glass. The plurality of light emitting units are three or more light emitting units,
The surface emitting laser module according to claim 1, wherein the plurality of light beams transmitted through the transparent member are equally spaced with respect to the at least one direction. The at least one direction is one specific direction;
The surface according to claim 1, wherein the transparent member has at least two inclined surfaces that are inclined with respect to both the traveling direction of the light and the specific direction. Light emitting laser module.   The surface emitting laser module according to claim 7, wherein a cross-sectional shape of the transparent member including a traveling direction of the light and the specific direction includes a V shape.   The surface emitting laser module according to claim 7, wherein a cross-sectional shape of the transparent member including the light traveling direction and the specific direction includes an inverted trapezoid.   The surface emitting laser module according to any one of claims 1 to 6, wherein the at least one direction is two directions of a first direction and a second direction.   The surface emitting laser module according to claim 10, wherein the first direction and the second direction are orthogonal to each other. An optical scanning device that scans a surface to be scanned with light,
A light source unit comprising the surface emitting laser module according to claim 1;
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;
13. An image forming apparatus comprising: at least one optical scanning device according to claim 12 that scans the at least one image carrier with light including image information.   The image forming apparatus according to claim 13, wherein the image information is color image information. An optical transmission module that generates an optical signal according to an input electrical signal,
A surface-emitting laser module according to any one of claims 1 to 11;
An optical transmission module comprising: a driving device that drives the surface emitting laser array element of the surface emitting laser module according to the input electric signal. An optical transmission module according to claim 15;
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;

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