JP6156694B2 - Optical device and image forming apparatus - Google Patents

Description

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

  In general, a ceramic package having excellent heat dissipation is used as a package member for holding electronic components, semiconductor elements, and the like (see, for example, Patent Document 1 and Patent Document 2).

  The ceramic package is provided with a seal ring for attaching a metal cap (lid) (see, for example, Patent Document 3 and Patent Document 4).

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

  However, the conventional optical device having the package member and the lid has insufficient reliability.

The present invention is provided between a light emitting element, a package member that holds the light emitting element in a cavity region, a lid that includes a transparent member that transmits light from the light emitting element, and the package member and the lid. The lid includes a seal ring to be welded, and the lid includes a flange portion that partially overlaps the seal ring, and a portion of the flange portion that does not overlap the seal ring is more than the seal ring. Ri Ah in part protrudes inwardly, the flange portion has two sides extending in a first direction, and said first two sides extending in a second direction perpendicular to the direction, said transparent The member is inclined so that a difference in height occurs in the first direction, and the flange portion is first welded on two sides extending in the first direction, and then extends in the second direction. One side is an optical device that is welded.

  According to the optical device of the present invention, reliability can be improved.

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 a surface emitting laser array chip. It is a top view of a flat package. It is AA sectional drawing of FIG. It is a figure for demonstrating the surface emitting laser array chip mounted in the chip mount part. It is a figure for demonstrating a seal ring. It is FIG. (1) for demonstrating a lid. FIGS. 15A and 15B are views (No. 2) for explaining the lid, respectively. It is a figure for demonstrating the reflective film and antireflection film which were provided in the glass plate. It is a figure for demonstrating the light reflected by a glass plate. It is a figure for demonstrating the roller electrode used for seam welding. It is a figure for demonstrating an example of the measurement result of distortion by Talysurf CCI6000. It is a figure for demonstrating the straight line at the time of calculating | requiring Dy. It is a figure for demonstrating Dy. It is a figure for demonstrating the relationship between a lid and a seal ring. It is a figure for demonstrating the relationship of B / A, Dy / Dx (average value), and 3 (sigma). It is a figure for demonstrating the relationship between D / C, Dy / Dx (average value), and 3 (sigma). FIG. 25A is a diagram for explaining the case where the value of D / C is approximately 1, and FIG. 25B is a diagram for explaining the case where the width of the seal ring is narrow. 26A is a diagram for explaining case 1, FIG. 26B is a diagram for explaining case 2, and FIG. 26C is a diagram for explaining case 3. FIG. FIG. 26D is a diagram for explaining the case 4. 27A is a diagram for explaining the measurement result of Case 1, FIG. 27B is a diagram for explaining the measurement result of Case 2, and FIG. 27C is the measurement of Case 3. It is a figure for demonstrating a result, FIG.27 (D) is a figure for demonstrating the measurement result of case 4. FIG. It is a figure for demonstrating Dy / Dx (maximum value), Dy / Dx (average value), Dy / Dx (minimum value), 3 (sigma) about case 1-case 4. FIG. It is a figure for demonstrating the relationship between a correlation coefficient and the determination of a correlation. It is FIG. (1) for demonstrating a correlation coefficient when a sample is limited by the value of Dy / Dx. It is FIG. (2) for demonstrating a correlation coefficient when a sample is limited by the value of Dy / Dx.

  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), transfer A belt 2040, a transfer roller 2042, a fixing device 2050, a paper feed roller 2054, a paper discharge roller 2058, a paper feed tray 2060, a paper discharge tray 2070, a communication control device 2080, and a printer control device 209 that comprehensively controls the above-described units. And and the like.

  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 program written in a code decipherable by the CPU, a ROM storing various data used when executing the program, a RAM as a working memory, an analog signal An AD converter circuit for converting the signal into a digital signal. 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. 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 correspondingly charged with light modulated for each color based on multi-color 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. That is, here, each photosensitive drum is an image carrier, and the surface of each photosensitive drum is a surface to be scanned. 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.

  By the way, in each photosensitive drum, an area scanned with light is called a “scanning area”. Further, the direction parallel to the rotation axis of each photosensitive drum is referred to as “main scanning direction”, and the rotational direction of each photosensitive drum is referred to as “sub-scanning direction”.

  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 light emitted from the corresponding light source, and makes the light substantially parallel light.

  Each aperture plate has an aperture and shapes the light through the corresponding coupling lens.

  Each cylindrical lens forms an image of the light 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 from the cylindrical lens 2204a and the light from the cylindrical lens 2204d. The second-stage (upper) polygon mirror reflects the light from the cylindrical lens 2204b and the cylindrical lens 2204c. Are arranged such that the light from each is deflected. Note that the first-stage polygon mirror and the second-stage polygon mirror are rotated with a shift of about 45 ° from each other, and writing scanning is alternately performed at the first stage and the second stage.

  The light 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 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).

  The light 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).

  The light from the cylindrical lens 2204d deflected by the optical deflector 2104 is guided to the photosensitive drum 2030d via 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.

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

  By the way, the package member for holding the 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 out downward from the periphery of the mounting portion, And a frame body that is laminated on the upper surface 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 thus manufactured, there is a surface emitting laser (VCSEL: Vertical Cavity Surface Emitting Laser). 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 interconnection, light sources for optical pickups, and light sources for image forming apparatuses such as laser printers, and some have been put into practical use.

  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 surface emitting laser array chip is reflected on the surface of the inclined transparent member fixed to the lid and used as the monitoring light beam. In this case, the photodiode that receives the monitoring light beam is housed in the cavity region of the package member together with the surface emitting laser array chip.

  In this embodiment, each light source has the optical device 10 as shown in FIGS. 7A to 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, a photodiode element 61, and the like.

  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.

  When the 40 light emitting units are orthogonally projected onto a virtual line extending in the sub-scanning corresponding direction (here, the same as the b-axis direction), the light emitting unit intervals are equal (“d1” in FIG. 9). It is arranged to be. In this specification, the “light emitting portion interval” refers to the distance between the centers of two light emitting portions.

  Each light emitting unit is a 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 and 11, a chip mount unit 21, a PD mount unit 22, and a plurality of connection terminals (not shown). Is a ceramic package having a package side secondary electrode region 23, a gold plating portion 24, and the like. FIG. 11 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. 12). 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.

  The photodiode element 61 is die-bonded to the PD mount unit 22. The anode electrode of the photodiode element 61 is electrically connected to the lead terminal by a bonding wire. The cathode on the back surface of the photodiode element 61 is electrically connected to the ground (GND) via a conductive adhesive. That is, the surface emitting laser array chip 60 and the photodiode element 61 are held on different ceramic layers.

  The plurality of connection terminals arranged in the package-side secondary electrode region 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 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 lid 40 can be further improved. Here, the plating thickness of the gold plating part 24 is about 1 μm.

  The outer shape of the flat package 20 is, for example, a square having a side length of about 13 mm. The thickness of the flat package 20 (size in the c-axis direction) 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 FIG. The seal ring 30 is a substantially square metal member having an opening formed so as to surround the cavity region.

  The seal ring 30 is made of Kovar (registered trademark) having a thermal expansion coefficient close to that of the ceramic 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. 14 as an example, the lid 40 includes a lid body 41 made of metal and a glass plate (lid glass) 42. As shown in FIGS. 15A and 15B, 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. Note that FIG. 15B is a cross-sectional view taken along the line AA in FIG.

  Here, as an example, the thickness (plate thickness) of the metal member constituting the lid body 41 is 0.15 mm, the height h1 of the rising portion 41a on the + a side is 2.5 mm, and the height of the rising portion 41a on the −a side. The length h2 is set to 0.6 mm. The flange portion 41b is processed so that the thickness of the tip portion 41d is as thin as 0.1 mm in order to make seam welding easy and reliable.

  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 inclined by a predetermined angle with respect to the plane orthogonal to the c-axis direction so that the light beam emitted from the surface emitting laser array chip 60 and reflected by the glass plate 42 enters the photodiode element 61. Attached to the inclined portion 41c. The glass plate 42 is fixed to the inclined portion 41 c with a low melting point glass 43 from the inside of the lid main body 41.

  As shown in FIG. 16, a reflective film 45 is formed on the −c side surface of the glass plate 42. As a result, the light emitted from the surface emitting laser array chip 60 can be reflected with a high reflectance and can be incident on the photodiode element 61. That is, a sufficient amount of light can be made incident on the photodiode element 61 as monitor light.

  An antireflection film 46 is formed on the surface of the glass plate 42 on the + c side. Thereby, interface reflection in the surface on the + c side is reduced, and the influence of the etalon effect can be reduced.

The reflection 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. The dielectric multilayer film is formed by alternately laminating a high refractive index material and a low refractive index material having a predetermined thickness 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 reflection film 45 preferably has a reflectance of 3% to 15%, and more preferably 5% to 12%. If the reflectance is too low, the S / N ratio of the signal output from the photodiode element 61 is lowered, and the light quantity control (APC: Auto Power Control) of the surface emitting laser array chip 60 cannot be performed accurately. If the reflectance is too high, the loss amount of the laser light emitted from the surface emitting laser array chip 60 increases, and it becomes impossible to obtain light having the power required for writing.

  In the present embodiment, the glass plate 42 can reflect a part of the light included in the region A in FIG. 17 and enter the photodiode element 61.

  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 multilayer film in which a high refractive index material and a low refractive index material having a predetermined film thickness are alternately laminated. It is comprised by. The antireflection film 46 preferably has a reflectance of 1% or less, and more preferably 0.5% or less.

  Next, the joining of the lid main body 41 and the seal ring 30 will be described.

  The lid main body 41 is placed on the seal ring 30 and positioned so that their outer shapes match. Next, the lid main body 41 and the seal ring 30 are joined by seam welding or the like. Incidentally, the outer shape of the lid body 41 is normally set to be slightly smaller than the outer shape of the seal ring 30. As an example, as shown in FIG. 18, two parallel sides are seam welded simultaneously by a tapered roller electrode 47. The weld location on the lid body 41 is basically only the tip of the flange portion 41b.

  However, conventionally, the lid main body 41 and the glass plate 42 are distorted due to heat during welding, which may cause strain variation and cracks in the glass plate 42. That is, the reliability was low.

  For the first time, the inventors of the present application have found that the relationship between the width of the seal ring 30 and the width of the flange portion 41b in the lid body 41 is largely related to the variation in strain in the glass plate 42. The experimental results will be described below.

  Here, Talysurf CCI6000 manufactured by Taylor Hobson was used as an apparatus for measuring the strain of the glass plate 42. In this apparatus, white light from a light source is irradiated onto the surface of the glass plate 42 via a beam splitter, and interference fringes are generated by the light reflected on the surface. Then, while the objective lens is driven in a direction orthogonal to the surface of the glass plate 42, the CCD receives light and calculates the position (peak position) with the highest light intensity in the interference fringe with high accuracy by the peak detection algorithm for each pixel. . That is, the peak position is calculated for each position on the glass plate 42.

  In FIG. 19, the measurement result of the glass plate 42 before the lid main body 41 is joined to the seal ring 30 is shown as a three-dimensional pattern image. Here, an axial direction parallel to the b-axis on the surface of the glass plate 42 is defined as an x-axis direction, and an axial direction orthogonal to the x-axis direction is defined as a y-axis direction (see FIG. 18). Then, the end on the + x side of the glass plate 42 is the origin of the position coordinates in the x-axis direction, and the end on the −y side is the origin of the position coordinates in the y-axis direction. The measurement results are based on the lowest peak position (0 μm).

  In FIG. 19, since the lid main body 41 is not distorted, a substantially perfect circular pattern can be confirmed. The strain observed at this time is an internal strain generated in the cooling process when the glass plate 42 is manufactured. By the way, when the glass plate 42 greatly distorted by the distortion of the lid main body 41 is measured, the pattern becomes an elliptical shape crushed in the horizontal direction.

  Then, as shown in FIG. 20, in the three-dimensional pattern image showing the measurement result, a straight line that passes through the lowest peak position (here, the central portion) and is parallel to the y-axis direction is drawn, as shown in FIG. Then, the relationship between the position in the y-axis direction on the straight line and the peak position, that is, the sectional view of the three-dimensional pattern image is obtained. Here, the difference between the minimum value and the maximum value of the peak position in this cross-sectional view is defined as the depth Dy in the y-axis direction. Similarly, Dx was also obtained in the x-axis direction. When the value of Dy / Dx was large, the elliptical state of the pattern was remarkable, and it was determined that the distortion of the glass plate 42 was large. In the following description, the value of Dy / Dx is obtained from the measurement result of the glass plate 42 when the lid body 41 is joined to the seal ring 30. Moreover, below, the distortion | strain of the glass plate 42 means the distortion | strain produced by welding.

  Further, as shown in FIG. 22, the width of the flange portion 41 b is D, the width of the portion overlapping the seal ring 30 is A, and the width of the portion protruding to the inside of the seal ring 30 is B. That is, D = A + B. In this embodiment, D = 1.1 mm.

  The thickness of the metal member constituting the lid main body 41 is 0.15 mm, and the thickness T of the seal ring 30 is 0.5 mm. The inclination angle θ of the glass plate 42 was 19 °, the height h1 of the rising portion 41a on the + a side was 2.5 mm, and the height h2 of the rising portion 41a on the −a side was 0.64 mm. Further, the outer shape of the lid body 41 is a square with a side length F of 7.8 mm, and the outer shape of the seal ring 30 is a square with a side length G of 8 mm. The width of the seal ring 30 is C.

  The reason why the outer size of the lid main body 41 is slightly smaller than the outer size of the seal ring 30 is that the lid 40 is placed on the seal ring 30 and a taper alignment jig is used. This is to absorb manufacturing errors in the size of the outer shape when aligning the four sides. Here, the lid body 41 and the seal ring 30 are designed to be positioned on the inner side of the seal ring 30 by 0.1 mm on one side because there is a difference of 0.2 mm in the size of the outer shape. . Of course, the relationship between the lid body 41 and the seal ring 30 is not limited to this. For example, the outer shape of the lid body 41 may be substantially the same, or the outer shape of the lid body 41 may be further smaller. However, when the difference between the size of the outer shape of the lid body 41 and the size of the outer shape of the seal ring 30 is too large, alignment and seam welding become difficult.

  FIG. 23 shows the relationship between the average value of Dy / Dx and B / A, and the relationship between 3σ indicating variation in Dy / Dx and B / A. Here, ten pieces of measurement data were obtained for each B / A. According to this, when the value of B / A becomes 0.3 or more, the average value of Dy / Dx and the value of 3σ are rapidly reduced.

  This is because if the B / A value is smaller than 0.3, the rising portion 41a of the lid body 41 is directly affected by the variation in the thickness of the seal ring 30 and the unevenness of the surface, and the glass plate 42 is distorted. It is presumed that it became easier. Further, when the value of B / A is 2.7 or more, it is assumed that the portion of the flange portion 41b that protrudes inward from the seal ring 30 is increased, and the value of 3σ is increased.

  The basis for determining whether or not the value of Dy / Dx is acceptable will be described later. Here, a case where the value of Dy / Dx is 3 or more and the value of 3σ is 2 or more is determined to be unacceptable. Therefore, the range (specified range) of B / A in which the value of Dy / Dx is less than 3 and the value of 3σ is less than 2 is 0.3 to 2.6.

  FIG. 24 shows the relationship between the average value of Dy / Dx and D / C, and the relationship between 3σ and D / C indicating variations in Dy / Dx. Here, ten pieces of measurement data were obtained for each D / C. According to this, when the value of D / C is 1.2 or more, the average value of Dy / Dx and the value of 3σ are rapidly reduced.

  As an example, as shown in FIG. 25A, when the D / C value is approximately 1, the rise portion of the lid is directly affected by the variation in the thickness of the seal ring and the surface irregularities. It is presumed that the glass plate is easily distorted. And it is considered that the above-mentioned influence is exerted until the value of D / C is 1.2.

  As an example, as shown in FIG. 25B, when the width of the seal ring is narrow, the inside of the flange portion is free. In this case, even if there is distortion or variation in thickness of the seal ring, the rise portion of the lid is not directly affected by the seal ring. In other words, the inner flange part has a free structure that absorbs distortion, and the influence of distortion other than welding conditions (variation in seal ring thickness and surface irregularities) is less likely to affect the glass plate. It is done.

  Further, when the value of D / C is 2.7 or more, the portion of the flange portion 41b that protrudes inward from the seal ring 30 is too large, so it is estimated that the value of 3σ has increased. The D / C range (specified range) in which the Dy / Dx value is less than 3 and the 3σ value is less than 2 is 1.2 to 2.7.

  By the way, the same measurement was performed when the inclination angle θ of the glass plate 42 was 0 °. In this case, the effect of defining the values of B / A and D / C was not as significant as when the inclination angle θ of the glass plate 42 was not 0 °, but the case where the inclination angle θ of the glass plate 42 was not 0 °. An effect of about 80% of the effect could be obtained. That is, it has been found that defining the values of B / A and D / C is effective for the optical device in which the lid is bonded to the seal ring.

Next, the influence of the order of the welding direction on the strain of the glass plate 42 will be described.
(1) Case 1
When B / A and D / C are within the specified range (B / A = 0.69, D / C = 1.47), first, seams along the a-axis direction along two sides separated with respect to the b-axis direction. A case where welding is performed and then two sides that are separated in the a-axis direction are seam-welded along the b-axis direction is referred to as “case 1” (see FIG. 26A).
(2) Case 2
When B / A and D / C are within the specified range (B / A = 0.69, D / C = 1.47), first, the two sides that are separated with respect to the a-axis direction are seamed along the b-axis direction. The case where the two sides separated with respect to the b-axis direction are then welded along the a-axis direction is referred to as “case 2” (see FIG. 26B).
(3) Case 3
When B / A and D / C are outside the specified range (B / A = 0.1, D / C = 1.0), first, seams along the a-axis direction along two sides that are separated with respect to the b-axis direction. The case where the two sides separated in the a-axis direction are then welded along the b-axis direction is referred to as “case 3” (see FIG. 26C).
(4) Case 4
When B / A and D / C are outside the specified range (B / A = 0.1, D / C = 1.0), first, seams along the b-axis direction along two sides that are separated with respect to the a-axis direction. A case where welding is performed and then two sides that are separated in the b-axis direction are seam-welded along the a-axis direction is referred to as “case 4” (see FIG. 26D).

  Ten samples were prepared for each case, and the strain of the glass plate 42 was measured using the Talysurf CCI6000. The measurement results Dy / Dx are averaged for each case, and the measurement results closer to the average value are shown in FIGS. 27 (A) to 27 (D). 27A shows the measurement result of case 1, FIG. 27B shows the measurement result of case 2, FIG. 27C shows the measurement result of case 3, and FIG. It is a measurement result. The average value of Dy / Dx was 1.59 in case 1, 3.18 in case 2, 5.21 in case 3, and 5.62 in case 4.

  As in Case 1, when B / A and D / C are within the specified range and seam welding is performed in advance in the a-axis direction, the distortion of the glass plate 42 is small. When two sides that are separated from each other in the b-axis direction are simultaneously seam welded along the a-axis direction, the heat generated at that time is transferred to the low-melting glass 43 and the glass plate 42 via the lid body 41 made of metal. Here, since the height of the rising portion 41a in the vicinity of the weld portion on the -b side is equal to the height of the rising portion 41a in the vicinity of the weld portion on the + b side, a temperature difference occurs between the low melting point glass 43 and the glass plate 42. Absent. After that, even if seam welding is performed along the b-axis direction, the temperature difference between the low melting point glass 43 and the glass plate 42 is small, and the strain of the glass plate 42 is considered to be small.

  As in case 2, when B / A and D / C were within the specified range and seam welding was performed prior to the b-axis direction, the distortion of the glass plate 42 was larger than that in case 1. When two sides that are separated from each other in the a-axis direction are simultaneously seam welded along the b-axis direction, the heat generated at that time is transferred to the low-melting-point glass 43 and the glass plate 42 via the lid body 41 made of metal. Here, since the height of the rising portion 41a in the vicinity of the welded portion on the -a side is lower than the height of the rising portion 41a in the vicinity of the welded portion on the + a side, in the low melting point glass 43 and the glass plate 42, the y-axis direction It is considered that a temperature difference occurred and the glass plate 42 was distorted.

  That is, when B / A and D / C are within the specified range, it can be seen that performing seam welding in advance in the a-axis direction has a great effect on further reducing strain generated in the glass plate 42.

  Further, as in case 3, when B / A and D / C are outside the specified range and seam welding is performed in advance in the a-axis direction, the glass plate 42 is greatly distorted compared to case 1 and case 2. .

  Further, when the seam welding is performed prior to the b-axis direction with B / A and D / C outside the specified range as in the case 4, the glass plate 42 is further distorted.

  When B / A and D / C were outside the specified range, the effect of strain reduction was slight even when seam welding was performed in advance in the a-axis direction.

  FIG. 28 shows the average value of Dy / Dx, the maximum value of Dy / Dx, the minimum value of Dy / Dx, and the value of 3σ of Dy / Dx for case 1 to case 4. Case 2 has a larger variation than Case 1. FIG. 28 also shows that when B / A and D / C are within the specified range, the order of seam welding has a very high effect of reducing variation. In addition, when B / A and D / C are out of the specified range, the rising portion 41a is substantially placed on the seal ring 30, so that variations in the surface state and height of the seal ring 30 have a great influence. It is considered that the effect of reducing variation due to the difference in welding sequence was small.

  By the way, in a conventional optical device, when a metal lid is seam welded to the seal ring to seal the ceramic package with the seal ring attached, the strain of the lid becomes larger than the heat of the welding, and the stress is transferred to the lid. The attached transparent member (for example, glass) was cracked, and there was a risk that the internal sealing performance was lost (leaked). In the optical device, when the internal sealing performance is lost, the light emitting element mounted inside may be corroded by being exposed to oxygen or moisture. In addition, when the lid is distorted, a phenomenon that the birefringence is increased due to the internal stress due to the stress, and a desired light flux may not be obtained.

  Therefore, the relationship between the value of Dy / Dx and the leak of the optical device was investigated. Among a plurality of optical devices prototyped by the present inventors, there were leaked products and OK products that did not leak. The value of Dy / Dx was measured for 30 samples of leaked products and 30 samples of OK products randomly extracted from these, and the correlation between Dy / Dx and the presence or absence of leakage was determined. The correlation R was calculated using a correlation coefficient formula shown by the following formula (1).

Here, a data string {(x _i , y _i )} (i = 1, 2,..., N) composed of two sets of numerical values is given, and the arithmetic average of the data x _i is expressed as x _av , data The arithmetic average of y _i is y _av . The data x _i is set as the presence / absence data of the leak, the presence of the leak is 0, and the absence of the leak is 1. Further, the data y _i is a value of Dy / Dx. Note that the determination of the correlation is shown in FIG.

  First, when the correlation coefficient between the value of Dy / Dx and the presence or absence of leakage was obtained for all samples, the value was 0.32 (there was some correlation). However, when the sample used for calculating the correlation coefficient is limited to the value of Dy / Dx instead of all of the above, the value of the correlation coefficient changed as shown in FIGS. For example, if the value of Dy / Dx is limited to samples exceeding 3, the value of the correlation coefficient is 0.47, and if the value of Dy / Dx is limited to samples exceeding 4, the value of the correlation coefficient is 0. 69. Further, when the value of Dy / Dx is limited to a sample exceeding 5, the value of the correlation coefficient is 0.75. When the value of Dy / Dx is limited to a sample exceeding 6, the value of the correlation coefficient is 0. 80.

  Here, when the value of Dy / Dx becomes larger than 3, it is determined that “there is a high correlation” between the value of Dy / Dx and the leak. Therefore, in this embodiment, the value of Dy / Dx is less than 3 as acceptable.

  As described above, the optical scanning device 2010 according to this embodiment includes four light sources (2200a, 2200b, 2200c, 2200d), four pre-deflector optical systems, an optical deflector 2104, four scanning optical systems, and A scanning control device is provided.

  Each light source includes a surface emitting laser array chip 60, a photodiode element 61 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 element 61 are held in a cavity region. 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 element 61, and the flat package 20 and the lid 40. The optical device 10 is provided and includes a lid 40 and a seal ring 30 to be welded.

  The lid 40 is set so that the value of B / A is in the range of 0.3 to 2.6 and the value of D / C is in the range of 1.2 to 2.7.

  Further, the glass plate 42 is inclined so as to have a height difference in the a-axis direction, and when the lid 40 is seam welded to the seal ring 30, two sides separated with respect to the b-axis direction are first along the a-axis direction. Seam welding is performed, and then two sides that are separated with respect to the a-axis direction are seam-welded along the b-axis direction.

  In this case, the lid 40 can be prevented from being largely distorted by the heat of welding. As a result, it is possible to prevent the glass plate 42 from cracking or losing its internal sealing performance. That is, it is possible to prevent the light emitting element mounted inside from being corroded by being exposed to oxygen or moisture. Moreover, the distortion of the glass plate 42 and the variation in distortion are reduced, and the photodiode element 61 can receive a desired amount of light. As a result, the S / N ratio of the signal output from the photodiode element 61 is improved, and the scanning control apparatus can accurately perform light amount control (APC: Auto Power Control) of the surface emitting laser array chip 60.

  Thus, according to the optical device 10 according to the present embodiment, reliability can be improved.

  Since the optical scanning device 2010 scans the surface of each photosensitive drum with the light emitted from the optical device 10 to form a latent image, a high-quality latent image can be stably formed.

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

  In addition, although the said embodiment demonstrated the case where the lid 40 was seam welded to the seal ring 30, it is not limited to this, Even if the lid 40 is joined to the seal ring 30 by methods other than seam welding. good.

  In the above embodiment, the case where the value of B / A is in the range of 0.3 to 2.6 and the value of D / C is in the range of 1.2 to 2.7 has been described. If the portion of the portion that does not overlap the seal ring is a portion that protrudes inward from the seal ring, the reliability can be improved as compared with the conventional case.

  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. However, the present invention is not limited to this, and a monochrome printer may be used.

  In the above-described embodiment, the image forming apparatus that transfers the toner image onto the recording paper has been described. However, the present invention is not limited to this. 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 , 45... Reflection film, 46. Antireflection film, 60... Surface emitting laser array chip (light emitting element), 61... Photodiode element (light receiving element), 2000 ... Color printer (image forming apparatus), 2010. , 2030a to 2030d ... photosensitive drum (image carrier), 2104 ... light deflector, 2105a to 2105d ... scanning lens (part of scanning optical system), 2200a to 2200d ... light source.

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

Claims (9)

A light emitting element;
A package member for holding the light emitting element in a cavity region;
A lid including a transparent member that transmits light from the light emitting element;
A seal ring provided between the package member and the lid and welded to the lid;
The lid has a flange portion partially overlapping the seal ring;
The portion of the flange portion that does not overlap the seal ring is a portion that protrudes inward from the seal ring,
The flange portion has two sides extending in a first direction and two sides extending in a second direction orthogonal to the first direction;
The transparent member is inclined so as to produce a height difference in the first direction,
The flange portion has two sides initially extending in the first direction are welded, then the two sides the optical devices that are welded extending in the second direction.   The optical device according to claim 1, wherein a width of the flange portion is larger than a width of the seal ring.   B / A is 0.3 to 2.6 using the width A of the portion of the flange portion that overlaps the seal ring and the width B of the portion of the flange portion that protrudes inward from the seal ring. The optical device according to claim 2, wherein the optical device falls within the range of   4. The optical device according to claim 2, wherein D / C is in a range of 1.2 to 2.7 using a width D of the flange portion and a width of the seal ring C. 5. The light emitting device, optical device according to any one of claims 1 to 4, characterized in that a surface emitting laser array chip. The retained in the cavity area of the package member, emitted from the light emitting element, according to any one of claims 1 to 5, further comprising a light receiving element for receiving light reflected by the transparent member Optical device. The optical device according to claim 6 , wherein the transparent member is provided with a reflective film on a surface on which light emitted from the light emitting element is incident. The transparent member, the surface opposite to the surface where the light emitted from the light emitting element is incident, according to any one of claims 1 to 7, characterized in that the anti-reflection film is provided Optical device. An image carrier;
A light source comprising the optical device according to any one of claims 1 to 8 ,
An image forming apparatus comprising: a scanning optical system that condenses light from the light source onto the image carrier.