JP2012185317A - Optical scanning unit, image reader, and image writing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more appropriately attach an upright equal magnification lens array to the housing of an optical scanning unit.SOLUTION: An optical scanning unit 10 comprises an upright equal magnification lens array plate 11 and a housing 12. The housing 12 includes: a bottom 37 on which the upright equal magnification lens array plate 11 is placed; a hole part 35 formed in the bottom 37 so as to pass light from the upright equal magnification lens array plate 11 through; hook engagement parts 36L and 36R; and projecting parts 38L and 38R provided on the bottom 37. The upright equal magnification lens array plate 11 has hook parts 33L and 33R and recessed parts 34L and 34R. When the upright equal magnification lens array plate 11 is fixed to the housing 12 by the engagement of the hook parts 33L and 33R with the hook engagement parts 36L and 36R, the recessed parts 34L and 34R fit on the projecting parts 38L and 38R respectively.

Description

  The present invention relates to an optical scanning unit used in an image reading apparatus or an image writing apparatus.

  Conventionally, an optical scanning unit such as a CIS (Contact Image Sensor) is used in an image reading device such as a scanner. Such an optical scanning unit is generally composed of a line-shaped light source, an erecting equal-magnification lens array, and a line image sensor. By employing an erecting equal-magnification imaging optical system using an erecting equal-magnification lens array, the optical scanning unit can be made more compact than in the case of a reduction imaging optical system.

  As an erecting equal-magnification lens array in the optical scanning unit, a rod lens array capable of forming an erecting equal-magnification image has been used, but in recent years, a plurality of micro convex lenses are regularly arranged on both sides. There has been proposed an erecting equal-magnification lens array plate in which a plurality of lens array plates are laminated so that the optical axes of the individual convex lenses coincide with each other (see, for example, Patent Document 1). Since such an erecting equal-magnification lens array plate can be formed by a method such as injection molding, the erecting equal-magnification lens array can be manufactured at a relatively low cost.

JP 2001-352429 A

  By the way, as a method of attaching the erecting equal-magnification lens array to the housing of the optical scanning unit, there is a method of fixing to a predetermined position of the housing using an adhesive.

  However, when fixing with an adhesive, it is necessary to hold the erecting equal-magnification lens array so that it does not move with a dedicated jig or the like at the time of fixing, and there is a problem that assembly workability is poor. In addition, since the housing of the optical scanning unit used in a scanner or the like is generally an elongated shape formed of resin, an unexpected force is applied at the time of inspection or mounting, the optical scanning unit is twisted, and a part of the adhesive May peel off.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique that can more suitably attach a lens array to a housing of an optical scanning unit.

  In order to solve the above problems, an optical scanning unit according to an aspect of the present invention includes a lens array and a housing that accommodates the lens array. The housing includes a mounting surface on which the lens array is mounted, a hole formed in the mounting surface for allowing light from the lens array to pass through, a hook engaging portion, and a convex provided on the mounting surface. A part. The lens array includes a hook portion that engages with the hook engaging portion, and a concave portion that fits the convex portion. When the erecting equal-magnification lens array is fixed to the housing by engaging the hook portion with the hook engaging portion, the concave portion and the convex portion are fitted.

  The convex portion may include a first convex portion and a second convex portion provided so as to sandwich the hole portion. The concave portion may include a first concave portion and a second concave portion that fit into the first convex portion and the second convex portion, respectively.

  The concave portion and the convex portion may be formed at least in the central portion in the main scanning direction.

  The hook portion may be provided at a substantially central portion in the height direction of the lens array.

  The lens array is an erecting equal-magnification lens array plate arranged so that a first lens array plate having a plurality of lenses formed on both sides and a second lens array plate are opposed to each other. An intermediate light shielding member for removing stray light may be provided between the two lens array plates, and the hook portion may be provided at an end portion in the sub-scanning direction of the intermediate light shielding member.

  Another aspect of the present invention is an image reading apparatus. This apparatus includes the above-described optical scanning unit.

  Yet another embodiment of the present invention is an image writing device. This apparatus includes the above-described optical scanning unit.

  It should be noted that any combination of the above-described constituent elements and a representation obtained by converting the expression of the present invention between a method, an apparatus, a system, and the like are also effective as an aspect of the present invention.

  According to the present invention, it is possible to more suitably attach the lens array to the housing of the optical scanning unit.

1 is a schematic sectional view of an image reading apparatus using an optical scanning unit according to an embodiment of the present invention. FIG. 2 is an enlarged view around an erecting equal-magnification lens array plate in the image reading apparatus shown in FIG. 1. 1 is a schematic cross-sectional view of an image writing apparatus using an optical scanning unit according to an embodiment of the present invention.

  FIG. 1 is a schematic sectional view of an image reading apparatus using an optical scanning unit according to an embodiment of the present invention. In FIG. 1, the horizontal direction is the sub-scanning direction, and the depth direction is the main scanning direction.

  As shown in FIG. 1, the image reading apparatus 100 moves the glass plate 14 as a document table on which the document G is placed, the optical scanning unit 10 for scanning and reading the document G, and the optical scanning unit 10. A drive mechanism (not shown) and an image processing unit (not shown) for processing data read by the optical scanning unit 10 are provided.

  The optical scanning unit 10 includes a linear light source 16 that irradiates light on a document G placed on a glass plate 14, an erecting equal-magnification lens array plate 11 that collects reflected light from the document G, and erecting A line image sensor 20 that receives the light condensed by the equal-magnification lens array plate 11 and a housing 12 that houses the line-shaped light source 16, the erecting equal-magnification lens array plate 11, and the line image sensor 20 are provided. The optical scanning unit 10 is mounted on the image reading apparatus 100 so that the longitudinal direction thereof coincides with the main scanning direction and the short side direction thereof coincides with the sub scanning direction.

  The housing 12 includes a base 12a, a light source mounting recess 12b formed on the upper surface of the base 12a, a lens array mounting recess 12c formed on the upper surface of the base 12a, and a sensor mounting formed on the lower surface of the base 12a. A recess 12d. The housing 12 is injection-molded with a resin material such as ABS resin or polycarbonate resin.

  The line light source 16 is a light source that emits substantially linear light. The linear light source 16 is fixed in the light source mounting recess 12b so that its optical axis passes through the intersection of the optical axis Ax of the erecting equal-magnification lens array plate 11 and the upper surface of the glass plate 14.

  The erecting equal-magnification lens array plate 11 receives substantially linear light reflected from the document G located above, and erects the same-magnification image on the image plane located below, that is, the light receiving surface of the line image sensor 20. Form. The detailed structure of the erecting equal-magnification lens array plate 11 and a method for fixing the erecting equal-magnification lens array plate 11 in the lens array mounting recess 12c will be described later.

  A line image sensor 20 is provided below the erecting equal-magnification lens array plate 11. The line image sensor 20 converts the light received from the erecting equal-magnification lens array plate 11 positioned above into an electric signal. The electrical signal is sent to an image processing unit (not shown) via wiring provided on the substrate 22.

  In the image reading apparatus 100, the light emitted from the line light source 16 is applied to the original G through the glass plate 14, and the reflected light from the original G is received by the line image sensor 20 via the erecting equal-magnification lens array plate 11. The original G is read by detecting it. By scanning the glass plate 14 with the optical scanning unit 10 in the sub-scanning direction, a desired area of the original G can be read.

  FIG. 2 is an enlarged view around the erecting equal-magnification lens array plate in the image reading apparatus shown in FIG. In FIG. 2, the horizontal direction is the sub-scanning direction, and the depth direction is the main scanning direction.

  First, the structure of the erecting equal-magnification lens array plate 11 will be described. The erecting equal-magnification lens array plate 11 is disposed so that the first lens array plate 24 and the second lens array plate 26 face each other. The first lens array plate 24 and the second lens array plate 26 are rectangular plates, and a plurality of convex lenses are arranged on both surfaces thereof. The first lens array plate 24 and the second lens array plate 26 are held by a holder 30.

  The first lens array plate 24 and the second lens array plate 26 are formed by injection molding. The material of the first lens array plate 24 and the second lens array plate 26 is preferably one that can be used for injection molding, has high light transmittance with respect to light in a necessary wavelength band, and low water absorption. Examples of desirable materials include cycloolefin resins, olefin resins, norbornene resins, and polycarbonates.

  A plurality of first lenses 24 a are arranged in a line along the longitudinal direction (main scanning direction) of the first lens array plate 24 on the outer surface (document side surface) of the first lens array plate 24. A plurality of second lenses 24 b are arranged in a line along the longitudinal direction of the first lens array plate 24 on the inner surface of the first lens array plate 24 (the surface facing the second lens array plate 26). Has been.

  On the inner surface of the second lens array plate 26 (the surface facing the first lens array plate 24), a plurality of third lenses 26a are provided along the longitudinal direction (main scanning direction) of the second lens array plate 26. Arranged in a row. A plurality of fourth lenses 26 b are arranged in a line along the longitudinal direction of the second lens array plate 26 on the outer surface (side surface of the line image sensor) of the second lens array plate 26.

  The first lens array plate 24 and the second lens array plate 26 are arranged so that a pair of corresponding first lens 24a, second lens 24b, third lens 26a, and fourth lens 26b constitutes a coaxial lens system. Laminated with the sides facing each other. In other words, the first lens array plate 24 and the second lens array plate 26 are laminated so that the optical axes of the corresponding first lens 24a, second lens 24b, third lens 26a, and fourth lens 26b coincide. .

  The holder 30 has a hollow quadrangular prism shape, and includes an upper surface portion 30a, a lower surface portion 30b, a left side surface portion 30L, and a right side surface portion 30R. The first lens array plate 24 and the second lens array plate 26 are held in a space formed by the upper surface portion 30a, the lower surface portion 30b, the left side surface portion 30L, and the right side surface portion 30R. The holder 30 is formed by a method such as injection molding using a light shielding material such as black ABS resin.

  In the present embodiment, the upper surface portion 30a and the lower surface portion 30b of the holder 30 have a function of shielding stray light that does not contribute to image formation. Therefore, in the following description, the upper surface portion 30a and the lower surface portion 30b are referred to as “first light shielding member 30a” and “second light shielding member 30b”, respectively.

  The outer surface of the first lens array plate 24 is covered with a plate-shaped first light shielding member 30a. A plurality of first through holes 30d are formed in the first light shielding member 30a. The first through holes 30d are formed in a line along the longitudinal direction (main scanning direction) of the first light shielding member 30a so as to correspond to the first lenses 24a of the first lens array plate 24. The first light shielding member 30a is provided so that each first through hole 30d is positioned in front of the corresponding first lens 24a.

  The outer surface of the second lens array plate 26 is covered with a plate-shaped second light shielding member 30b. A plurality of second through holes 30e are formed in the second light shielding member 30b. The second through holes 30e are formed in a line along the longitudinal direction (main scanning direction) of the second light shielding member 30b so as to correspond to the fourth lenses 26b of the second lens array plate 26. The second light shielding member 30b is provided so that each second through hole 30e is positioned in front of the corresponding fourth lens 26b.

  As shown in FIG. 2, an intermediate light shielding member 32 is provided between the first lens array plate 24 and the second lens array plate 26. The intermediate light shielding member 32 also has a function of shielding stray light that does not contribute to image formation.

  The intermediate light shielding member 32 is a plate-shaped light shielding member made of a light shielding material, and has a plurality of intermediate through holes 32a. The intermediate through holes 32a are formed in a line along the longitudinal direction (main scanning direction) of the intermediate light shielding member 32 so as to correspond to the second lens 24b and the third lens 26a. The intermediate light shielding member 32 is provided so that each intermediate through hole 32a is positioned in front of the corresponding second lens 24b and third lens 26a. The intermediate light shielding member 32 is held by the left side surface portion 30L and the right side surface portion 30R of the holder 30.

  In the present embodiment, the intermediate light shielding member 32 is formed so that the end in the sub-scanning direction extends outside the holder 30. A hook portion is provided at the end portion. That is, as shown in FIG. 2, the left end portion in the sub-scanning direction of the intermediate light shielding member 32 extends outward from the left side surface 30L of the holder 30, and is bent vertically downward at a position spaced a predetermined distance from the left side surface 30L. The left hook portion 33L. All portions bent downward are the left hook portions 33L. The right end portion in the sub-scanning direction of the intermediate light shielding member 32 extends outward from the right side surface portion 30R of the holder 30, and is bent vertically downward at a position spaced a predetermined distance from the right side surface portion 30R to form a right hook portion 33R. ing. All the parts bent downward are the right hook portions 33R.

  In the present embodiment, a left concave portion 34L is formed between the left hook portion 33L and the left side surface portion 30L, and a right concave portion 34R is formed between the right hook portion 33R and the right side surface portion 30R.

  Next, the structure of the housing 12 to which the above erecting equal-magnification lens array plate 11 is attached will be described. As shown in FIG. 2, the erecting equal-magnification lens array plate 11 is fixed in a lens array mounting recess 12 c formed on the upper surface of the housing 12.

  An elongated hole 35 extending in the main scanning direction of the optical scanning unit is formed on the bottom surface 37 of the lens array mounting recess 12c as a mounting surface of the erecting equal-magnification lens array plate 11. The elongated hole 35 is provided to allow light from the erecting equal-magnification lens array plate 11 to pass through the line image sensor.

  A left hook engaging portion 36L for engaging the left hook portion 33L of the erecting equal-magnification lens array plate 11 is formed on the left side wall 12e of the lens array mounting recess 12c. A right hook engaging portion 36R for engaging the right hook portion 33R of the erecting equal-magnification lens array plate 11 is formed on the right side wall 12f of the recess 12c.

  Furthermore, a left convex portion 38L and a right convex portion 38R are provided on the bottom surface 37 of the lens array mounting concave portion 12c so as to sandwich the hole portion 35 therebetween. The left convex portion 38L and the right convex portion 38R are formed to extend in the main scanning direction. The left convex portion 38L and the right convex portion 38R can also be referred to as two “rails” extending in parallel to each other in the main scanning direction.

  Next, attachment of the erecting equal-magnification lens array plate 11 to the housing 12 will be described. The erecting equal-magnification lens array plate 11 is inserted into the lens array mounting recess 12c from the upper opening. When the erecting equal-magnification lens array plate 11 is pushed into the lens array mounting recess 12c until the second light shielding member 30b of the erecting equal-magnification lens array plate 11 contacts the bottom surface 37 of the lens array mounting recess 12c, the left hook portion 33L and the right hook portion 33R engage with the left hook engaging portion 36L and the right hook engaging portion 36R, respectively. As a result, the erecting equal-magnification lens array plate 11 is fixed to the housing 12. At this time, the left concave portion 34L and the right concave portion 34R are fitted into the left convex portion 38L and the right convex portion 38R, respectively.

  The housing 12 has an elongated shape formed by resin molding, and is provided with an elongated hole 35 extending in the main scanning direction, so that the rigidity is not so high. Therefore, the housing 12 is easily deformed when a force is applied. Specifically, the hole 35 is deformed so that the width in the sub-scanning direction is narrowed, or the hole 35 is deformed so that the width in the sub-scanning direction is widened. Due to the deformation of the housing, for example, when the erecting equal-magnification lens array plate 11 and the housing 12 are fixed with an adhesive, the adhesive may be peeled off.

  On the other hand, in the present embodiment, when the erecting equal-magnification lens array plate 11 is fixed to the housing 12 as described above, the left concave portion 34L and the right concave portion 34R are fitted into the left convex portion 38L and the right convex portion 38R, respectively. Due to the configuration, the deformation of the housing 12 is suppressed. Specifically, for example, when a force from the outside toward the inside is applied to the housing 12, the left convex portion 38L and the right convex portion 38R are the left side surface portion 30L and the right side surface portion 30R of the erecting equal-magnification lens array plate 11, respectively. Receives reaction force from the outside. Thereby, deformation of the housing 12 is suppressed. For example, when a force from the inside toward the outside is applied to the housing 12, the left convex portion 38L and the right convex portion 38R are respectively connected to the left hook portion 33L and the right hook portion 33R of the erecting equal-magnification lens array plate 11. Receives an inward reaction force. Thereby, deformation of the housing 12 is suppressed.

  In the present embodiment, since the hook structure is used to fix the erecting equal-magnification lens array plate 11 and the housing 12, even if the housing 12 is slightly deformed when the force is applied, the force is applied. If no longer exists, the original fixed state is restored. On the other hand, when the erecting equal-magnification lens array plate 11 and the housing 12 are fixed with an adhesive, once the adhesive is peeled off by the application of force, the original fixed state is restored even if the application of force is lost. There is no.

  According to the present embodiment, the adoption of the hook structure has the advantage that the mounting is completed simply by fitting the erecting equal-magnification lens array plate 11 into the lens array mounting recess 12c. Since there is no process of fixing the erecting equal-magnification lens array plate to a dedicated jig as in the case of using an adhesive or the process of waiting for the adhesive to harden, the assembly workability can be improved and the manufacturing cost can be reduced. . Further, since no adhesive is used, it is possible to avoid a situation where the adhesive adheres to the lens.

  As described above, the mounting structure of the erecting equal-magnification lens array plate 11 and the housing 12 according to the present embodiment has many advantages compared to the mounting structure using an adhesive.

  The left convex portion 38L and the right convex portion 38R, and the left concave portion 34L and the right concave portion 34R may be provided continuously over both ends of the optical scanning unit 10 in the main scanning direction, or may be provided intermittently. . When provided intermittently, the deformation of the housing 12 is generally greatest at the central portion in the main scanning direction. Therefore, the left convex portion 38L and the right convex portion 38R, and the left concave portion 34L and the right concave portion 34R are at least an optical scanning unit. It is desirable to provide 10 at the center in the main scanning direction.

  In the above-described embodiment, the left hook portion 33L and the right hook portion 33R are provided on the intermediate light shielding member 32 positioned substantially at the center of the erecting equal-magnification lens array plate 11 in the height direction. As in the present embodiment, the left hook portion 33L and the right hook portion 33R are disposed substantially at the center in the height direction of the erecting equal-magnification lens array plate 11, so that both sides in the sub-scanning direction with respect to the document surface side of the housing 12 are arranged. The deformation of the housing 12 can be preferably suppressed both in the case where the outward force is applied and in the case where the outward force is applied to the line image sensor side of the housing 12.

  The left hook portion 33L and the left hook engaging portion 36L, and the right hook portion 33R and the right hook engaging portion 36R are preferably formed at different positions in the main scanning direction when priority is given to the stability during assembly. . This is because when the two are formed at the same position in the main scanning direction, it is necessary to engage the hook portion at the same time on the left and right sides, and the possibility of deformation of the housing 12 and malfunction of the engagement increases.

  Further, when a shape such as the left hook engaging portion 36L or the right hook engaging portion 36R is made by injection molding, an undercut structure is required. When the undercut structure is adopted, a space is required for the undercut portion to be nested. However, when both are formed at the same position in the main scanning direction, it is difficult to secure this space. Therefore, from the viewpoint of actual manufacturing, it is desirable that the left hook portion 33L and the left hook engaging portion 36L and the right hook portion 33R and the right hook engaging portion 36R are formed at different positions in the main scanning direction. For example, the left hook portion 33L and the left hook engaging portion 36L, and the right hook portion 33R and the right hook engaging portion 36R may be arranged so as to be alternately arranged in the main scanning direction.

  However, when priority is given to the optical characteristics of the erecting equal-magnification lens array plate 11, the left hook portion 33L and the left hook engaging portion 36L, and the right hook portion 33R and the right hook engaging portion 36R are in the main scanning direction. In the same position. In this case, since the erecting equal-magnification lens array plate 11 is joined to the housing 12 at a symmetrical position with respect to the main scanning direction, the optical axis of the lens system is unlikely to be bent.

  In the above-described embodiment, the erecting equal-magnification lens array plate is used as the lens array. However, the lens array is not limited to this. For example, a lens array having a structure in which a plurality of rod lenses are arranged in a row may be used. Good. The lens array is not limited to that of an erecting equal-magnification imaging optical system, and may be a lens array of a reduction imaging optical system, for example.

  In the above-described embodiment, the holder 30 has a hollow quadrangular prism shape. However, the intermediate light shielding member 32 may be sandwiched between the first light shielding member 30a and the second light shielding member 30b.

  FIG. 3 is a schematic sectional view of an image writing apparatus using the optical scanning unit according to the embodiment of the present invention. As shown in FIG. 3, the image writing apparatus 200 includes an optical scanning unit 220, a photosensitive drum 208 that receives light emitted from the optical scanning unit 220, a control unit 202, and a housing that houses the above-described components. A body 210. The optical scanning unit 220 includes an LED array 206 in which a plurality of LEDs are arranged in an array, a substrate 204 on which the LED array 206 is mounted, and an erecting equal-magnification lens array that collects light emitted from the LED array 206. A plate 11 and a housing 212 that houses the above-described components are provided. Light emission of the LED array 206 is controlled by the control unit 202. In FIG. 3, a developing device, a transfer device, and the like provided around the photosensitive drum 208 are not shown.

  The image writing apparatus 200 is a so-called LED print head type image writing apparatus using LEDs as light sources. The LED print head system has a one-to-one correspondence between pixels and light emission sources, and does not require a scanning mechanism. Therefore, the apparatus can be reduced in size and weight as compared with a laser ROS (Raster Output Scanner) method combining a laser light source and a polygon mirror.

  Also in this embodiment, the erecting equal-magnification lens array plate 11 and the housing 12 are fixed by the same hook structure as that of the optical scanning unit 10 shown in FIGS. Further, the deformation of the housing 12 is suppressed by the concave-convex fitting structure similar to that of the optical scanning unit 10 shown in FIGS.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  10, 220 optical scanning unit, 11 erecting equal-magnification lens array plate, 12, 212 housing, 14 glass plate, 16 line light source, 20 line image sensor, 22 substrate, 24 first lens array plate, 26 second lens array Plate, 30 Holder, 32 Intermediate light shielding member, 33L Left hook part, 33R Right hook part, 34L Left recessed part, 34R Right recessed part, 35 hole part, 36L Left hook engaging part, 36R Right hook engaging part, 38L Left convex part 38R right convex part, 100 image reading apparatus, 200 image writing apparatus, 202 control part, 206 LED array, 208 photoconductor drum.

Claims (7)

An optical scanning unit comprising a lens array and a housing that houses the lens array,
The housing is
A mounting surface on which the lens array is mounted;
In order to allow light from the lens array to pass therethrough, a hole formed in the mounting surface,
A hook engaging portion;
A convex portion provided on the mounting surface,
The lens array is
A hook portion engaged with the hook engaging portion;
A concave portion that fits with the convex portion,
The optical scanning unit is characterized in that the concave portion and the convex portion are fitted when the lens array is fixed to the housing by engaging the hook portion with the hook engaging portion. The convex portion includes a first convex portion and a second convex portion provided so as to sandwich the hole portion,
2. The optical scanning unit according to claim 1, wherein the concave portion includes a first concave portion and a second concave portion that are fitted to the first convex portion and the second convex portion, respectively.   The optical scanning unit according to claim 1, wherein the concave portion and the convex portion are formed at least in a central portion in the main scanning direction.   The optical scanning unit according to claim 1, wherein the hook portion is provided at a substantially central portion in the height direction of the lens array. The lens array is an erecting equal-magnification lens array plate disposed so that a first lens array plate and a second lens array plate on which a plurality of lenses are formed on both sides face each other,
An intermediate light blocking member for removing stray light is provided between the first lens array plate and the second lens array plate,
5. The optical scanning unit according to claim 1, wherein the hook portion is provided at an end portion in the sub-scanning direction of the intermediate light shielding member.   An image reading apparatus comprising the optical scanning unit according to claim 1.   An image writing apparatus comprising the optical scanning unit according to claim 1.

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