JP2014135307A - Optical device, optical scanner, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device capable of reducing variations in output of a light receiving element.SOLUTION: The optical device includes: a surface light emitting laser array chip (light emitting element); a photodiode (light receiving element) for monitoring the intensity of light emission of the surface light emitting laser array chip; a flat package (package member) 20 that stores the surface light emitting laser array chip and the photodiode in a cavity area; a lid having a glass plate (transparent member) that reflects a part of light beams emitted from the surface light emitting laser array chip toward the photodiode; and a seal ring 30 that is provided between the flat package and the lid. When orthogonal projection is performed on a plane parallel to a bottom face of the cavity area, a side of at least one wall face close to at least the photodiode in the cavity area is in contact with at least one side of an inner periphery of the seal ring at at least one portion, and a deviation angle of the cavity area and the seal ring is 1.5° or less.

Description

  The present invention relates to an optical device, an optical scanning apparatus, and an image forming apparatus, and more particularly, to an optical device having a package member, an optical scanning apparatus having the optical device, and an image forming apparatus including the optical scanning apparatus.

  Generally, a ceramic package excellent in heat dissipation is used as a package member for holding electronic components, semiconductor elements, and the like (see, for example, Patent Document 1).

  The ceramic package has a seal ring for attaching a metal cap (lid) (see, for example, Patent Document 2 and Patent Document 3).

  Further, Patent Document 4 discloses a ceramic package intended to improve the sealing performance of the cavity.

  Further, Patent Document 5 discloses a shield component for an optical module including a light emitting element and a light receiving element.

  However, the conventional package member holding the light emitting element has a disadvantage that the output of the light receiving element varies greatly when the light receiving element for monitoring is incorporated.

  The present invention relates to a light emitting element, a light receiving element for monitoring the amount of light emitted from the light emitting element, a package member in which the light emitting element and the light receiving element are held in a cavity region, and a luminous flux emitted from the light emitting element. A lid having a transparent member partially reflecting toward the light receiving element; and a seal ring provided between the package member and the lid for sealing the cavity region; and a bottom surface of the cavity region At least a part of at least one wall surface close to the light receiving element in the cavity region and at least one side of the inner periphery of the seal ring are in contact with each other at least partially, In this optical device, the deviation angle between the cavity region and the seal ring is 1.5 ° or less.

  According to the optical device of the present invention, variations in the output of the light receiving element can be reduced.

1 is a diagram for describing a schematic configuration of a color printer according to an embodiment of the present invention. FIG. FIG. 2 is a diagram (part 1) for describing the optical scanning device in FIG. 1; FIG. 3 is a second diagram for explaining the optical scanning device in FIG. 1; FIG. 3 is a third diagram for explaining the optical scanning device in FIG. 1; FIG. 4 is a diagram (part 4) for explaining the optical scanning device in FIG. 1; It is a figure for demonstrating the conventional light source unit. FIG. 7A and FIG. 7B are diagrams for explaining an optical device, respectively. It is AA sectional drawing of FIG. 7 (A). It is a figure for demonstrating the several light emission part in a surface emitting laser array chip. It is a top view of a flat package. It is a side view of a flat package. It is AA sectional drawing of FIG. It is a figure for demonstrating a seal ring. FIG. 14 is a side view of FIG. 13. It is AA sectional drawing of FIG. It is FIG. (1) for demonstrating a lid. FIGS. 17A and 17B are views (No. 2) for explaining the lid, respectively. It is a figure for demonstrating a glass plate. FIG. 19A to FIG. 19E are diagrams for explaining a conventional method of attaching a seal ring. It is a figure for demonstrating deviation | shift angle | corner (theta). FIG. 21A and FIG. 21B are diagrams for explaining the influence of the deviation of the seal ring on the coupling efficiency. It is a figure for demonstrating the relationship between (DELTA) Ef obtained by simulation, and deviation | shift angle | corner (theta). FIG. 23A and FIG. 23B are views (No. 1) for explaining a method of attaching the seal ring in the present embodiment, respectively. FIGS. 24A and 24B are views (No. 2) for describing a method of attaching the seal ring in the present embodiment, respectively. FIGS. 25A to 25C are views (No. 3) for describing a method of attaching the seal ring in the present embodiment, respectively. FIGS. 26A to 26C are views (No. 4) for describing a method of attaching the seal ring in the present embodiment, respectively. FIGS. 27A and 27B are views (No. 5) for describing a method of attaching the seal ring in the present embodiment, respectively. It is a figure for demonstrating the effect of the method of attaching the seal ring in this embodiment. It is a figure for demonstrating the modification of the method of attaching the seal ring in this embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a color printer 2000 according to an embodiment.

  The color printer 2000 is a tandem multi-color printer that forms a full-color image by superimposing four colors (black, cyan, magenta, and yellow), and includes an optical scanning device 2010, four photosensitive drums (2030a, 2030b, 2030c, 2030d), four cleaning units (2031a, 2031b, 2031c, 2031d), four charging devices (2032a, 2032b, 2032c, 2032d), four developing rollers (2033a, 2033b, 2033c, 2033d), 4 Toner cartridges (2034a, 2034b, 2034c, 2034d), transfer belt 2040, transfer roller 2042, fixing device 2050, paper feed roller 2054, paper discharge roller 2058, paper feed tray 2060, paper discharge tray 2070 A printer control device 2090 for controlling the communication control unit 2080, and the above units overall.

  The communication control device 2080 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  The printer control device 2090 includes a CPU, a ROM described in a program written in code readable by the CPU, various data used when executing the program, a RAM as a working memory, an analog data An A / D conversion circuit for converting the data into digital data. Then, the printer control device 2090 notifies the optical scanning device 2010 of multi-color image information from the host device received via the communication control device 2080.

  The photosensitive drum 2030a, the charging device 2032a, the developing roller 2033a, and the cleaning unit 2031a are used as a set, and constitute an image forming station (hereinafter also referred to as “K station” for convenience) that forms a black image.

  The photosensitive drum 2030b, the charging device 2032b, the developing roller 2033b, and the cleaning unit 2031b are used as a set, and constitute an image forming station (hereinafter also referred to as “C station” for convenience) that forms a cyan image.

  The photosensitive drum 2030c, the charging device 2032c, the developing roller 2033c, and the cleaning unit 2031c are used as a set, and constitute an image forming station (hereinafter also referred to as “M station” for convenience) that forms a magenta image.

  The photosensitive drum 2030d, the charging device 2032d, the developing roller 2033d, and the cleaning unit 2031d are used as a set, and constitute an image forming station (hereinafter also referred to as “Y station” for convenience) that forms a yellow image.

  Each photosensitive drum has a photosensitive layer formed on the surface thereof. That is, the surface of each photoconductive drum is a surface to be scanned. Each photosensitive drum is rotated in the direction of the arrow in the plane of FIG. 1 by a rotation mechanism (not shown).

  Each charging device uniformly charges the surface of the corresponding photosensitive drum.

  The optical scanning device 2010 is charged correspondingly with a light beam modulated for each color based on multicolor image information (black image information, cyan image information, magenta image information, yellow image information) from the printer control device 2090. The surface of the photosensitive drum is scanned. Thereby, a latent image corresponding to the image information is formed on the surface of each photosensitive drum. The latent image formed here moves in the direction of the corresponding developing device as the photosensitive drum rotates. The configuration of the optical scanning device will be described later.

  As each developing roller rotates, toner from a corresponding toner cartridge (not shown) is thinly and uniformly applied to the surface thereof. Then, when the toner on the surface of each developing roller comes into contact with the surface of the corresponding photosensitive drum, the toner moves only to a portion irradiated with light on the surface and adheres to the surface. In other words, each developing roller causes toner to adhere to the latent image formed on the surface of the corresponding photosensitive drum so as to be visualized. Here, the toner-attached image (toner image) moves in the direction of the transfer belt 2040 as the photosensitive drum rotates.

  The yellow, magenta, cyan, and black toner images are sequentially transferred onto the transfer belt 2040 at a predetermined timing, and are superimposed to form a color image.

  Recording paper is stored in the paper feed tray 2060. A paper feed roller 2054 is disposed in the vicinity of the paper feed tray 2060. The paper feed roller 2054 takes out the recording paper one by one from the paper feed tray 2060. The recording paper is sent out toward the gap between the transfer belt 2040 and the transfer roller 2042 at a predetermined timing. As a result, the color image on the transfer belt 2040 is transferred to the recording paper. The recording paper on which the color image is transferred is sent to the fixing device 2050.

  In the fixing device 2050, heat and pressure are applied to the recording paper, thereby fixing the toner on the recording paper. The recording paper on which the toner is fixed is sent to the paper discharge tray 2070 via the paper discharge roller 2058 and is sequentially stacked on the paper discharge tray 2070.

  Each cleaning unit removes toner (residual toner) remaining on the surface of the corresponding photosensitive drum. The surface of the photosensitive drum from which the residual toner has been removed returns to the position facing the corresponding charging device again.

  Next, the configuration of the optical scanning device 2010 will be described.

  2 to 5 as an example, the optical scanning device 2010 includes four light sources (2200a, 2200b, 2200c, 2200d), four coupling lenses (2201a, 2201b, 2201c, 2201d), four openings. Plate (2202a, 2202b, 2202c, 2202d), four cylindrical lenses (2204a, 2204b, 2204c, 2204d), optical deflector 2104, four scanning lenses (2105a, 2105b, 2105c, 2105d), six folding mirrors ( 2106a, 2106b, 2106c, 2106d, 2108b, 2108c) and a scanning control device (not shown).

  Here, in the XYZ three-dimensional orthogonal coordinate system, the direction along the longitudinal direction (rotational axis direction) of each photosensitive drum is defined as the X-axis direction, and the direction parallel to the rotational axis of the optical deflector 2104 is defined as the Z-axis direction. To do.

  In the following, in each optical member, a direction corresponding to the main scanning direction is abbreviated as “main scanning corresponding direction”, and a direction corresponding to the sub scanning direction is abbreviated as “sub scanning corresponding direction”.

  The light source 2200a, the coupling lens 2201a, the aperture plate 2202a, the cylindrical lens 2204a, the scanning lens 2105a, and the folding mirror 2106a are optical members for forming a latent image on the photosensitive drum 2030a.

  The light source 2200b, the coupling lens 2201b, the aperture plate 2202b, the cylindrical lens 2204b, the scanning lens 2105b, the folding mirror 2106b, and the folding mirror 2108b are optical members for forming a latent image on the photosensitive drum 2030b.

  The light source 2200c, the coupling lens 2201c, the aperture plate 2202c, the cylindrical lens 2204c, the scanning lens 2105c, the folding mirror 2106c, and the folding mirror 2108c are optical members for forming a latent image on the photosensitive drum 2030c.

  The light source 2200d, the coupling lens 2201d, the aperture plate 2202d, the cylindrical lens 2204d, the scanning lens 2105d, and the folding mirror 2106d are optical members for forming a latent image on the photosensitive drum 2030d.

  Each coupling lens is disposed on the optical path of the light beam emitted from the corresponding light source, and makes the light beam a substantially parallel light beam.

  Each aperture plate has an opening, and shapes the light beam via the corresponding coupling lens.

  Each cylindrical lens forms an image of the light beam that has passed through the opening of the corresponding aperture plate in the vicinity of the deflection reflection surface of the optical deflector 2104 in the Y-axis direction.

  The optical system disposed on the optical path between each light source and the optical deflector 2104 is also called a pre-deflector optical system.

  The optical deflector 2104 has a two-stage polygon mirror. Each polygon mirror has four deflecting reflecting surfaces. The first-stage (lower) polygon mirror deflects the light beam from the cylindrical lens 2204a and the light beam from the cylindrical lens 2204d. The second-stage (upper) polygon mirror deflects the light beam from the cylindrical lens 2204b and the cylindrical lens 2204c. Are arranged so as to be deflected respectively. Note that the first-stage polygon mirror and the second-stage polygon mirror rotate with a phase shift of approximately 45 ° from each other, and writing scanning is alternately performed in the first and second stages.

  The light beam from the cylindrical lens 2204a deflected by the optical deflector 2104 is guided to the photosensitive drum 2030a through the scanning lens 2105a and the folding mirror 2106a.

  The light beam from the cylindrical lens 2204b deflected by the optical deflector 2104 is guided to the photosensitive drum 2030b through the scanning lens 2105b and the two folding mirrors (2106b and 2108b).

  Further, the light beam from the cylindrical lens 2204c deflected by the optical deflector 2104 is guided to the photosensitive drum 2030c via the scanning lens 2105c and the two folding mirrors (2106c and 2108c).

  Further, the light beam from the cylindrical lens 2204d deflected by the optical deflector 2104 is guided to the photosensitive drum 2030d through the scanning lens 2105d and the folding mirror 2106d.

  The light spot on the surface of each photosensitive drum moves along the longitudinal direction of the photosensitive drum as the optical deflector 2104 rotates.

  The moving direction of the light spot on each photosensitive drum is the “main scanning direction”, and the rotating direction of the photosensitive drum is the “sub-scanning direction”.

  An optical system disposed on the optical path between the optical deflector 2104 and each photosensitive drum is also called a scanning optical system.

  In general, a package member for holding a light emitting element includes a mounting portion on which the light emitting element is mounted, a base having a mounting portion or a pair of metallized wiring members led downward from the periphery of the mounting portion, And a frame body provided on the upper surface of the base body and provided with an opening for forming a cavity region. Further, a wiring pattern for supplying power to the light emitting element is formed on the bottom surface of the cavity region by a plated metal layer. This package member is manufactured through the following steps.

  First, a base green sheet made of ceramic is prepared, and a through hole is formed in the base green sheet for passing the metallized wiring member.

  Next, a frame green sheet made of ceramic is prepared, and a through-hole serving as a cavity region is formed in the frame green sheet.

  Subsequently, a metal paste for a metallized wiring member is applied by screen printing or the like from the upper surface to the lower surface of the base green sheet. The metal paste is obtained by kneading a metal powder such as tungsten or molybdenum with an organic binder and a solvent.

  Further, the metal paste for the metallized metal layer is applied to the inner surface of the through hole of the frame green sheet by a screen printing method or the like. In the printing on the through hole, generally, a method is adopted in which a metal paste is applied to one end of the through hole and the inside of the through hole is printed while sucking from the other end.

  Then, the frame green sheet is placed on the base green sheet, a ceramic substrate is produced by pressurization and heating, and further fired at a high temperature.

  Then, nickel, silver or the like is plated on the exposed surfaces of the mounting portion, the metallized wiring conductor and the metallized metal layer.

  As an example of the light emitting element held in the package member manufactured in this manner, there is a surface emitting laser (Vertical Cavity Surface Emitting Laser: VCSEL). A surface-emitting laser is a semiconductor laser that emits light in a direction perpendicular to the substrate surface, and is characterized by low cost and high performance compared to conventional edge-emitting lasers, and in addition, it can be easily arrayed. doing. For this reason, studies have been made on light sources for optical communication such as optical interconnections, light sources for optical pickups, and light sources for image forming apparatuses such as laser printers, and some have been put into practical use.

  By the way, in the image forming apparatus, the light quantity of the scanning light beam changes with temperature change or time-dependent change, and there is a possibility that density unevenness may occur in the finally output image (output image). Therefore, in order to suppress this, an optical scanning device normally receives a part of the light beam emitted from the light source as a monitor light beam by a detector such as a photodiode, and controls the output level of the light source based on the result. APC (Auto Power Control) is implemented.

  In an optical scanning device using an edge-emitting laser, APC is performed by monitoring light emitted backward from the edge-emitting laser. However, because of the structure of the surface-emitting laser, there is no light emitted backward, so in an optical scanning device using a surface-emitting laser, a part of the light beam emitted from the surface-emitting laser is branched to the photodetector. Thus, a method of performing APC based on the output of the photodetector has been considered.

  FIG. 6 shows a conventional light source unit 14 having a laser module 500 and an optical module 600.

  The laser module 500 is mounted with an optical device 510 in which a surface emitting laser array chip is held by a package member, a laser control device (not shown) for driving and controlling the surface emitting laser array chip, the optical device 510 and the laser control device. The printed circuit board (PCB) substrate 580 is provided.

  The optical module 600 includes a first part 610 and a second part 630. The first portion 610 includes a half mirror 611, a condenser lens 612, and a light receiving element 613. The second portion 630 includes a coupling lens 631 and an aperture plate 632.

  The first portion 610 is disposed on the + c side of the optical device 510 so that the half mirror 611 is positioned on the optical path of the light emitted from the optical device 510. A part of the light incident on the half mirror 611 is reflected in the −b direction and is received by the light receiving element 613 via the condenser lens 612. The light receiving element 613 outputs a signal (photoelectric conversion signal) corresponding to the amount of received light to the laser control device of the laser module 500.

  The second portion 630 is disposed on the + c side of the first portion 610 so that the coupling lens 631 is positioned on the optical path of the light transmitted through the half mirror 611. The coupling lens 631 makes light transmitted through the half mirror 611 substantially parallel light. The aperture plate 632 has an aperture and shapes the light that has passed through the coupling lens 631. The light that has passed through the opening of the opening plate 632 becomes light emitted from the light source unit 14.

  However, the light source unit 14 has a disadvantage of high manufacturing cost.

  Therefore, it has been devised that a part of the light beam emitted from the light emitting element is reflected on the surface of the inclined transparent member fixed to the lid and used as a monitoring light beam. In this case, the photodiode that receives the monitoring light beam can be accommodated in the cavity region of the package member together with the light emitting element.

  In the present embodiment, each light source has an optical device 10 as shown in FIG. 7A to FIG. 8 as an example. FIG. 8 is a cross-sectional view taken along the line AA in FIG.

  The optical device 10 includes a flat package 20, a seal ring 30, a lid 40, a surface emitting laser array chip 60, and a photodiode PD.

  Here, a direction orthogonal to the bottom surface of the flat package 20 is defined as a c-axis direction, and two directions orthogonal to each other in a plane orthogonal to the c-axis direction are defined as an a-axis direction and a b-axis direction. The a-axis direction is set to the main scanning corresponding direction, and the b-axis direction is set to the sub-scanning corresponding direction.

  As an example, the surface emitting laser array chip 60 includes 40 light emitting units arranged two-dimensionally as shown in FIG. Note that the number of light emitting units is not limited to 40.

  The 40 light emitting units are arranged so that the intervals between the light emitting units are equal (“d1” in FIG. 9) when all the light emitting units are orthogonally projected onto a virtual line extending in the sub-scanning corresponding direction. In this specification, the “light emitting portion interval” refers to the distance between the centers of two light emitting portions.

  Here, each light emitting unit is a vertical cavity surface emitting laser having an oscillation wavelength of 780 nm band. In other words, the surface-emitting laser array chip 60 is obtained by integrating 40 surface-emitting lasers.

  Since the surface emitting laser array chip 60 has 40 light emitting portions and has a large number of terminals, it is extremely difficult to accommodate the surface emitting laser array chip 60 in a so-called can package. Therefore, the surface emitting laser array chip 60 is housed in the flat package 20 that can be mounted on the surface and from which terminals serving as leads can be easily taken out.

  The flat package 20 is a flat package called CLCC (Ceramic leaded chip carrier). As an example, as shown in FIGS. 10 to 12, a chip mount unit 21, a PD mount unit 22, a plurality of connection terminals 23, a gold It is a ceramic package having a plating part 24 and the like. 12 is a cross-sectional view taken along the line AA in FIG. The flat package 20 is formed by laminating a plurality of ceramic layers.

  The flat package 20 has a recess called a cavity region on the + c side surface.

  The chip mount portion 21 is a portion on which the surface emitting laser array chip 60 is mounted, and is the bottom surface of the cavity region. The chip mount portion 21 is provided with a metal film. This metal film is also called a die attach area and serves as a common electrode.

  The surface-emitting laser array chip 60 is approximately at the center of the chip mount portion 21 and is die-bonded on the metal film using a solder material such as AuSn (see FIG. 8). That is, the surface emitting laser array chip 60 is held on the bottom surface of the cavity region surrounded by the wall.

  A plurality of lead terminals (not shown) extend radially from the chip mount portion 21 toward the outer periphery of the flat package 20. The plurality of lead terminals are electrically connected to the plurality of terminals of the surface emitting laser array chip 60 by bonding wires. In the following, the ceramic layer provided with the chip mount portion 21 is also referred to as “ceramic layer A”.

  The PD mount 22 is provided on a ceramic layer (hereinafter also referred to as “ceramic layer B”) laminated on the + c side of the ceramic layer A.

  The photodiode PD is die-bonded to the PD mount 22. The anode electrode of the photodiode PD is electrically connected to the lead terminal by a bonding wire. The cathode on the back surface of the photodiode PD is electrically connected to the ground (GND) through a conductive adhesive. That is, the surface emitting laser array chip 60 and the photodiode PD are held on different ceramic layers. Here, the size of the light receiving surface of the photodiode PD is φ1.2 mm.

  The plurality of connection terminals 23 are terminals for electrically connecting the surface emitting laser array chip 60 to a printed circuit board or the like, and are also called castellations. The plurality of connection terminals 23 are individually electrically connected to the plurality of lead terminals.

  The gold plating part 24 is provided so as to surround the cavity region. The gold plating portion 24 is formed by electroplating that is denser and has better adhesion than electroless plating. Thereby, the airtightness inside the cap 40 can be improved more. Here, the plating thickness of the gold plating part 24 is about 1 μm.

  The outer shape of the flat package 20 is a square having a side length C (see FIG. 11) of approximately 13 mm. The thickness D (see FIG. 11) of the flat package 20 is about 2 mm.

  As an example, the seal ring 30 is attached to the + c side of the gold plating part 24 as shown in FIGS. The seal ring 30 is a substantially square metal member having an opening formed so as to surround the cavity region. The size of the opening is set to be approximately the same as the size of the cavity region when the cavity region is orthogonally projected onto a plane orthogonal to the c-axis direction.

  The seal ring 30 is made of Kovar having a thermal expansion coefficient close to that of the ceramic that is the material of the flat package 20. The surface of the seal ring 30 is gold plated. The seal ring 30 is fixed to the gold plating part 24 using silver solder.

  As shown in FIG. 16 as an example, the lid 40 includes a lid main body 41 made of metal and a glass plate 42. As shown in FIGS. 17A and 17B, the lid body 41 includes a rising portion 41a extending in the c-axis direction, and a flange portion 41b provided at an end portion on the −c side of the rising portion 41a. And an inclined portion 41c provided at the end of the rising portion 41a on the + c side. Here, as an example, the symbol H in FIG. 17A is 0.1 mm, the symbol h1 is 2.5 mm, and the symbol h2 is 0.5 mm.

  The flange portion 41 b is a flat portion connected to the seal ring 30. The inclined part 41c is a part to which the glass plate 42 is attached. The glass plate 42 is orthogonal to the c-axis direction so that a light beam emitted from the surface emitting laser array chip 60 and reflected by the glass plate 42 (hereinafter also referred to as “monitoring light beam”) enters the photodiode PD. It is attached to the inclined portion 41c while being inclined by a predetermined angle with respect to the surface. Here, as an example, the inclination angle is about 15 °.

  The glass plate 42 is fixed to the inclined portion 41c with a low melting point glass 43 from the inside of the lid main body 41 (see FIG. 16). As an example, as shown in FIG. 18, the glass plate 42 has a reflection film 45 formed on the −c side surface and an antireflection film 46 formed on the + c side surface.

  A light beam emitted from the surface emitting laser array chip 60 and transmitted through the glass plate 42 is a light beam emitted from the light source, and becomes a scanning light beam for optically scanning the corresponding photosensitive drum.

  The reflectance of the reflective film 45 is preferably 3% to 15%. When the reflectance is lower than 3%, the level of the monitor signal corresponding to the amount of received light generated by the photodiode PD becomes small, and the S / N of the signal output from the photodiode PD decreases. On the other hand, when the reflectance is higher than 15%, the light quantity of the scanning light beam is reduced. The reflectance of the antireflection film 46 is preferably 1% or less.

The reflective film 45 is formed of a metal film made of thin gold (Au) or the like that transmits light with a predetermined transmittance, or a mirror made of a dielectric multilayer film. In the dielectric multilayer film, a high refractive index material and a low refractive index material having a predetermined thickness are alternately laminated so as to function as a mirror. Examples of the high refractive index material include ZnS—SiO ₂ and TiO ₂ , and examples of the low refractive index material include SiO ₂ . The antireflection film 46 is a dielectric film having a refractive index lower than the refractive index of the glass plate 42, or a dielectric in which a high refractive index material and a low refractive index material having a predetermined film thickness are alternately laminated. It is composed of a multilayer film.

  The scanning control device performs APC of each light emitting unit based on the output signal of the photodiode PD at every predetermined timing.

Here, a conventional method of attaching the seal ring will be described with reference to FIGS. 19 (A) to 19 (E).
(A-1) A rectangular mounting jig is set so as to cover the cavity region of the flat package 20 (see FIG. 19A).
(A-2) A fusion sheet having a rectangular opening at the center is attached so as to be fitted into an attachment jig (see FIG. 19B). A silver brazing material having a thickness of about several tens of μm is often used for the fusion sheet.
(A-3) The seal ring is attached so as to be fitted into the attachment jig (see FIGS. 19C and 19D).
(A-4) Heat to a temperature at which the fused sheet dissolves. When the fused sheet is a silver brazing material, it is heated at 400 ° to 500 ° for several hours.
(A-5) Remove the mounting jig (see FIG. 19E).

  By the way, since ceramic shrinks by about 20 to 30% when fired, it is difficult to obtain a flat package having a strict size. Therefore, the size of the portion to be inserted into the cavity region in the mounting jig must be made smaller with a margin with respect to the size of the cavity region. Further, the fusion sheet and the seal ring 30 must be easily fitted with a gap with respect to the size of the outer shape of the mounting jig.

  In this case, there is “rattle” of the mounting jig with respect to the cavity region, and “rattle” of the fusion sheet and the seal ring 30 with respect to the mounting jig, and the seal ring 30 is attached to the flat package 20. On the other hand, there is a possibility of being attached in a state of being rotated around an axis parallel to the c-axis direction (see FIG. 20). Hereinafter, the rotation angle θ is also referred to as “shift angle θ”. In FIG. 20, the shift angle θ is exaggerated for easy understanding.

  The ratio of the light amount of the light beam reflected by the glass plate 42, that is, the ratio of the light amount of the light beam received by the photodiode PD to the light amount of the monitoring light beam is called "coupling efficiency".

For each coupling efficiency of a plurality of light emitting units, the highest coupling efficiency is Efmax, the lowest coupling efficiency is Efmin, and the value ΔEf calculated from the following equation (1) is expressed as “variation in coupling efficiency between channels”. "
ΔEf = 100 {1- (Efmin / Efmax)} (1)

  When ΔEf exceeds 20%, the difference in coupling efficiency between the light emitting units becomes large, and the APC control becomes complicated.

  Since the photodiode PD is accommodated in the flat package 20, the size of the photodiode PD must be as small as possible. Therefore, the monitoring light flux of the light emitting portion arranged outside of the 40 light emitting portions is set so that the center thereof is incident near the outer peripheral portion of the light receiving surface of the photodiode PD (FIG. 21A). )reference). Further, when it is assumed that the light emitting portion is at the center of the surface emitting laser array, the center of the monitoring light beam of the light emitting portion is set to coincide with the center of the light receiving surface of the photodiode PD. In this case, ΔEf can be about 8%.

  At this time, if the deviation angle θ is large, as shown in FIG. 21B as an example, the center of each monitor light beam is the center of the surface emitting laser array according to the slip direction and the magnitude of the deviation angle θ. Move on a circle centered on the position. In addition, the dashed-dotted line in FIG. 21 (B) has shown the movement path | route of the center of the monitoring light beam of the light emission part v5.

  As is clear from FIGS. 21A and 21B, when the deviation angle θ is increased, the amount of light received by the light emitting portion v5 at the photodiode PD is reduced. That is, the value of Efmin becomes small.

  At this time, the value of Efmax hardly changes because there is a light emitting part in which the center of the monitoring light beam moves from the vicinity of the outer periphery of the light receiving surface of the photodiode PD to the center.

  Therefore, ΔEf is expected to increase as the deviation angle θ increases.

  FIG. 22 shows the relationship between ΔEf and deviation angle θ obtained by simulation. According to this, ΔEf suddenly increases when the deviation angle θ exceeds 1.5 °. Therefore, in this embodiment, in order to perform the APC control efficiently, the target is to set the deviation angle θ to 1.5 ° or less so that ΔEf does not exceed 20%.

Next, the attachment method of the seal ring in this embodiment is demonstrated using FIG. 23 (A)-FIG. 27 (B).
(B-1) A block-shaped top 70 having a size slightly smaller than the cavity region and having a length in the c-axis direction longer than the depth of the cavity region when orthogonally projected onto a plane orthogonal to the c-axis direction is prepared ( (See FIGS. 23A and 23B). That is, the top 70 can be fitted into the cavity region.
(B-2) The frame 70 is inserted into the cavity region (see FIG. 24A).
(B-3) The frame 70 is pressed against one corner on the + a side in the cavity region (see FIG. 24B). In FIG. 24B, the frame 70 is pressed against the corner “a” on the + a side and the −b side.
(B-4) Fit the fused sheet into the top 70 (see FIGS. 25A and 25B). Note that the size of the opening portion of the fusion sheet is set to be approximately the same as the size of the cavity region when the cavity region is orthogonally projected onto a plane orthogonal to the c-axis direction.
(B-5) One corner on the + a side in the opening of the fused sheet is pressed against the corner of the facing top 70 (see FIG. 25C).
(B-6) The seal ring 30 is fitted into the top 70 (see FIGS. 26A and 26B).
(B-7) One corner on the + a side in the opening of the seal ring 30 is pressed against the corner of the facing top 70 (see FIG. 26C).
(B-8) Heat to a temperature at which the fused sheet dissolves. When the fused sheet is a silver brazing material, it is heated at 400 ° to 500 ° for several hours.
(B-9) Remove the top 70 (see FIGS. 27A and 27B).

  In this case, when orthogonally projected onto a plane orthogonal to the b-axis direction, of the four wall surfaces in the cavity region, the side of the + a side wall closest to the photodiode PD and the side of the + a side in the opening of the seal ring 30 And overlap. In addition, when orthogonally projected onto a plane orthogonal to the b-axis direction, among the four wall surfaces in the cavity region, the −b side wall side and the −b side side in the opening of the seal ring 30 overlap. .

  The deviation angle θ of each of the 100 flat packages to which the seal ring was attached by the attachment method of the present embodiment and the 100 flat packages to which the seal ring was attached by the conventional attachment method was measured. The measurement results are shown in FIG.

  In 100 flat packages to which the seal ring was attached by the attachment method in the present embodiment, the deviation angle θ was 1.5 ° or less in all cases. Further, the variation in the deviation angle θ was extremely small as compared with 100 flat packages to which seal rings were attached by the conventional attachment method.

  That is, ΔEf can be stably reduced to 20% or less by attaching the seal ring using the attachment method of the present embodiment. As a result, the manufacturing yield of the optical device can be improved.

  By the way, when orthogonally projecting on a plane orthogonal to the b-axis direction, when the side of one wall surface in the cavity region and one side of the opening of the seal ring 30 are overlapped, the side on the + a side closest to the photodiode PD Must be prioritized. The reason is that if the + a side is overlapped, the distance between the surface emitting laser array chip 60 and the glass plate 42 does not change even if the seal ring 30 is slightly displaced in the b-axis direction with respect to the cavity region. However, if a deviation occurs in the a-axis direction, the distance between the surface emitting laser array chip 60 and the glass plate 42 changes, and the light receiving position of the monitoring light beam in the photodiode PD changes.

  The amount of deviation in the b-axis direction with respect to the cavity region of the seal ring 30 is preferably less than ½ times the interval between the two light emitting portions located at both ends of the surface emitting laser array chip 60 in the b-axis direction. .

  When the seal ring 30 is attached to the flat package 20, the surface emitting laser array chip 60 and the photodiode PD are subsequently attached at predetermined positions, and are electrically connected to a plurality of lead terminals by bonding wires. Thereafter, the lid 40 is attached to the seal ring 30.

  As described above, according to the optical scanning device 2010 according to the present embodiment, the four light sources (2200a, 2200b, 2200c, 2200d), the four pre-deflector optical systems, the optical deflector 2104, the four scanning optical systems, And a scanning control device.

  Each light source includes a surface-emitting laser array chip 60, a photodiode PD for monitoring the amount of light emitted from the surface-emitting laser array chip 60, and the surface-emitting laser array chip 60 and the photodiode PD are held in a cavity region. Provided between the flat package 20, the lid 40 having a glass plate 42 that reflects a part of the light beam emitted from the surface emitting laser array chip 60 toward the photodiode PD, and between the flat package 20 and the lid 40, The optical device 10 is provided with a seal ring 30 for sealing the cavity region.

  When manufacturing this optical device 10, the seal ring 30 is attached to the flat package 20 through the steps (B-1) to (B-9). When the seal ring 30 attached in this way is orthogonally projected onto a plane orthogonal to the b-axis direction, the + a side wall side closest to the photodiode PD in the cavity region is the side of the + a side wall surface in the cavity region. And the −b side edge of the opening overlaps the −b side wall side of the cavity region.

  In this case, the deviation angle θ can be stably reduced to 1.5 ° or less, whereby ΔEf can be stably reduced to 20% or less. Therefore, the scanning control apparatus can efficiently perform APC control. As a result, the optical scanning apparatus 2010 can stably form a high-quality latent image. In addition, the manufacturing yield of the optical device 10 can be improved, and the cost of the optical scanning device 2010 can be reduced.

  Since the color printer 2000 includes the optical scanning device 2010, a high-quality image can be stably formed as a result.

  In (B-7) above, the + a side of the opening of the seal ring 30 may be pressed against the top 70.

  Moreover, although the said embodiment demonstrated the case where the oscillation wavelength of a light emission part was a 780 nm band, it is not limited to this. The oscillation wavelength of the light emitting unit may be changed according to the characteristics of the photoreceptor.

  The optical device can also be used for applications other than the image forming apparatus. In that case, the oscillation wavelength may be a wavelength band such as a 650 nm band, an 850 nm band, a 980 nm band, a 1.3 μm band, and a 1.5 μm band depending on the application.

  In the above embodiment, the case of a color printer as the image forming apparatus has been described.

  In the above-described embodiment, the image forming apparatus that transfers the toner image to the recording paper has been described. However, the present invention is not limited to this. For example, the laser beam is directly applied to a medium (for example, paper) that develops color by laser light. May be an image forming apparatus that emits light.

  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.

  DESCRIPTION OF SYMBOLS 10 ... Optical device, 20 ... Flat package (package member), 30 ... Seal ring, 40 ... Lid, 41 ... Lid main body, 41a ... Rising part, 41b ... Flange part, 41c ... Inclined part, 42 ... Glass plate (transparent member ), 60... Surface emitting laser array chip (light emitting element), 70. Top (frame member), 2000. Color printer (image forming apparatus), 2010. Optical scanning device, 2030 a to 2030 d. 2104... Optical deflectors, 2105 a to 2105 d... Scanning lens (part of the scanning optical system), 2200 a to 2200 d... Light source, PD.

JP 11-260949 A JP 2011-222663 A JP 63-104355 A JP 2007-027592 A JP 2007-300031 A

Claims (5)

A light emitting element;
A light receiving element for monitoring the amount of light emitted from the light emitting element;
A package member in which the light emitting element and the light receiving element are held in a cavity region;
A lid having a transparent member that reflects a part of a light beam emitted from the light emitting element toward the light receiving element;
A seal ring provided between the package member and the lid, for sealing the cavity region;
When orthogonally projected onto a plane parallel to the bottom surface of the cavity region, at least a side of at least one wall surface near the light receiving element in the cavity region and at least one side of the inner periphery of the seal ring are at least partially. An optical device that is in contact with each other, and a deviation angle between the cavity region and the seal ring is 1.5 ° or less. A light emitting element;
A light receiving element for monitoring the amount of light emitted from the light emitting element;
A package member in which the light emitting element and the light receiving element are held in a cavity region;
A lid having a transparent member that reflects a part of a light beam emitted from the light emitting element toward the light receiving element;
A seal ring provided between the package member and the lid, for sealing the cavity region;
When orthogonally projected onto a plane parallel to the bottom surface of the cavity region, at least a part of at least two wall surfaces near the light receiving element in the cavity region and at least two sides of the inner periphery of the seal ring are at least a part. An optical device that is in contact with each other, and a deviation angle between the cavity region and the seal ring is 1.5 ° or less.   The optical device according to claim 1, wherein a reflectance of the transparent member is 3% to 15% with respect to light emitted from the light emitting element. An optical scanning device that scans a surface to be scanned with light,
A light source comprising the optical device according to claim 1;
An optical deflector for deflecting light from the light source;
An optical scanning device comprising: a scanning optical system that condenses the light deflected by the optical deflector onto the surface to be scanned. An image carrier;
An image forming apparatus comprising: the optical scanning device according to claim 4, wherein the image carrier is scanned with light modulated according to image information.