Lens mirror array

According to one embodiment, there is provided the lens mirror array in which a plurality of optical elements includes one pair or more of first light blocking surfaces that are formed by sharing sides thereof with the first mirror surface at positions nipping the symmetrical surface in the arrangement direction of the optical elements, a second light blocking surface that is formed on a side close to the second lens surface further than the first mirror surface on the same side as the first mirror surface of the optical elements, a concave portion configuring one pair of third light blocking surfaces that are formed to be recessed from the second light blocking surface in a direction orthogonal to the second light blocking surface over the adjacent two optical elements.

FIELD

Embodiments described herein relate generally to a lens mirror array and an image forming apparatus containing a lens mirror array.

BACKGROUND

An image forming apparatus forms a latent image (electrostatic latent image) on a photoconductive drum by forming an image by light emitted from LED arrays, on the photoconductive drum, of one row or a plurality of rows in which an operation of turning on and off according to image data (print data) for printing is performed through an optical component (lens mirror array) configured in a line shape. The image forming apparatus attaches toner (developer) to the latent image formed on the photoconductive drum, forms a toner image on a paper sheet by transferring the toner of the latent image onto a paper sheet, and forms an image on the paper sheet by fixing the toner image.

In addition, the image forming apparatus forms an image by reflected light radiated on the paper sheet through the lens mirror array, on an image sensor configured in one row or a plurality of rows in a line shape. The image forming apparatus obtains an image of the paper sheet by converting charges accumulated in the image sensor into a digital signal to be read.

The lens mirror array includes a structure in which a plurality of optical elements are arranged, an optical element including a first lens surface on which light is incident, a first mirror surface that reflects the light incident on the first lens surface, a second mirror surface that reflects the light reflected by the first mirror surface, and a second lens surface that emits the light reflected by the second mirror surface. In addition, a lens mirror array, is disclosed in JP-A-2016-138947, in which a light blocking surface for preventing the light incident on the first lens surface in a certain optical element from entering other optical elements is provided.

DETAILED DESCRIPTION

In general, according to one embodiment, the lens mirror array includes a pair of light blocking surfaces arranged for each optical element along an arrangement direction of the optical elements. The pair of light blocking surfaces are provided at positions which share sides thereof with the first mirror surface, respectively.

The lens mirror array is formed by injection molding. For this reason, a curved surface is formed at a corner portion of a mold due to a corner R of a tool used for manufacturing the mold. In addition, there is a possibility that a resin cannot be filled into a tip of an edge portion of the mold at the time of molding. As a result, the curved surface is formed between the light blocking surface and the first mirror surface of the lens mirror array. For this reason, since a part of the light incident on the first lens surface is reflected by the curved surface between the light blocking surface and the first mirror surface, there is a possibility that the part of the light becomes stray light reaching the second mirror surface of other optical elements or the second lens surface. There is a problem that the accuracy of forming an image on the paper sheet and acquiring an image of the paper sheet by occurrence of the stray light, decreases.

An object of the embodiment is to provide a lens mirror array and an image forming apparatus with highly accurate image formation and image obtainment, and less stray light.

According to one embodiment, there is provided a lens mirror array in which a plurality of optical elements are arranged, an optical element including a first lens surface on which light is incident, a first mirror surface that reflects the light incident on the first lens surface, a second mirror surface that reflects the light reflected by the first mirror surface, and a second lens surface that emits the light reflected by the second mirror surface, and the first lens surface, the first mirror surface, the second mirror surface, and the second lens surface are respectively symmetrically formed with respect to a symmetrical surface orthogonal to an arrangement direction of the optical elements, in which the optical element includes one pair or more of first light blocking surfaces that are formed by sharing sides thereof with the first mirror surface at positions nipping the symmetrical surface in the arrangement direction of the optical elements, a second light blocking surface that is formed on a side close to the second mirror surface further than the first mirror surface on the same side as the first mirror surface of the optical elements, a concave portion configuring one pair of third light blocking surfaces that are formed to be recessed from the second light blocking surface in a direction orthogonal to the second light blocking surface over the adjacent two optical elements, and inclined with respect to an arrangement direction of the optical elements, and a light blocking layer that is formed over the first light blocking surface, the second light blocking surface, and the third light blocking surface.

Hereinafter, an image forming apparatus and a lens mirror array according to a first embodiment will be described with reference to drawings.

First, an image forming apparatus1according to the first embodiment will be described.FIG. 1is a diagram for explaining a configuration example of the image forming apparatus1according to the first embodiment.

For example, the image forming apparatus1is a solid scan type printer (for example, LED printer) that performs various processes of image formation or the like while a recording medium of a paper sheet P or the like is transported. The image forming apparatus1charges a photoconductive drum and forms a latent image (electrostatic latent image) on the photoconductive drum by forming an image by light emitted from LED arrays, on the photoconductive drum, of one row or a plurality of rows in which an operation of turning on and off according to image data (print data) for printing is performed through optical components (lens mirror array) configured in a line shape. In addition, the image forming apparatus1attaches toner (developer) to the latent image formed on the photoconductive drum, and forms a toner image on a paper sheet P by transferring the toner attached to the latent image on the paper sheet P. In addition, the image forming apparatus1nips the paper sheet P on which the toner image is formed, between fixing rollers heated to a high temperature by a heater so as to fix the toner image formed on the paper sheet P.

In addition, the image forming apparatus1also functions as an image reading apparatus obtaining an image of the paper sheet P by forming an image by reflected light of light radiated on the paper sheet P, on an image sensor by the lens mirror array, and converting charges accumulated in the image sensor into a digital signal to be read.

The image forming apparatus1includes a casing11, a document platen12, a scanner unit13, an automatic document feeder (ADF)14, a paper feed cassette15, a paper discharge tray16, an image forming unit17, a transporting unit18, and a main control unit19. Furthermore, the image forming apparatus1may include an operation I/F for receiving an operation input, a communication I/F for communicating with other apparatuses, or the like. The document platen12, the scanner unit13, and the automatic document feeder (ADF)14are parts configuring the image reading apparatus.

The casing11is a main body that holds the document platen12, the scanner unit13, the ADF14, the paper feed cassette15, the paper discharge tray16, the image forming unit17, the transporting unit18, and the main control unit19.

The document platen12is a part on which the paper sheet P as a document is placed. The document platen12includes a glass plate21on which the paper sheet P as the document is placed and a space23located on the opposite side of a placement surface22on which the paper sheet P as the document on the glass plate21is placed.

The ADF14is a mechanism for transporting the paper sheet P. The ADF14is provided above the document platen12so as to be freely opened and closed. The ADF14takes the paper sheet P disposed in a tray, and transports the taken paper sheet P while closely contacting with the glass plate21of the document platen12.

The scanner unit13obtains an image from the paper sheet P. The scanner unit13is disposed in the space23opposite to the placement surface22of the document platen12.FIG. 2is a diagram for explaining a configuration example of the scanner unit13. The scanner unit13includes an image sensor31, a lens mirror array32, an illumination33, a light blocking body34, a casing35, and a substrate36.

The image sensor31is an imaging element in which pixels for converting light into an electric signal (image signal) are arranged in a line shape. An arrangement direction of the pixels of the image sensor31is referred to as a main scan direction M1. For example, the image sensor31is configured by a CCD (charged coupled device), a CMOS (complementary metal oxide semiconductor), or other imaging elements.

The lens mirror array32is an optical component for forming an image by light from a predetermined reading range on the pixel of the image sensor31. The reading range of the lens mirror array32is a rectangular region on the placement surface22of the document platen12. The lens mirror array32forms an image by light, on the pixel of the image sensor31, reflected by the paper sheet P placed on the placement surface22of the document platen12and transmitted through the glass plate21. A detailed configuration of the lens mirror array32will be described below.

The illumination33irradiates the paper sheet P with light. The illumination33includes a light source and a light guide body that irradiates the paper sheet P with the light from the light source. The illumination33irradiates a region including the reading range of the lens mirror array32by the light guide body with the light emitted from the light source.

The light blocking body34is a member for blocking the light. For example, the light blocking body34is a member applied with a light blocking material on a surface thereof. The light blocking body34is configured in a shape and at a position which prevent light from a region other than the reading range of the lens mirror array32from entering the lens mirror array32.

The casing35is a member that supports and positions the image sensor31, the lens mirror array32, the illumination33, the light blocking body34, and the substrate36. In addition, the casing35includes a light blocking unit that blocks a part of light emitted from the lens mirror array32. The light blocking unit blocks light that becomes stray light when light is incident on the image sensor31, or light emitted from the lens mirror array32in a direction not incident on the image sensor31.

The substrate36is a component on which the image sensor31, a signal processing unit that obtains an image by reading of the image signal from the image sensor31and performing signal processing with respect to the image signal, a memory that temporarily stores an image, and the like, are mounted.

When the paper sheet P is placed on the placement surface22of the document platen12, the scanner unit13is driven by a drive mechanism (not shown) in a sub-scan direction S1that is a direction orthogonal to the main scan direction M1and in parallel with the placement surface22. The scanner unit13obtains the entire image of the paper sheet P disposed on the placement surface22of the document platen12by being driven in the sub-scan direction S1and continuously obtaining an image line by line by the image sensor31.

In addition, when the paper sheet P is transported by the ADF14, the scanner unit13is driven at a position facing a position to which the paper sheet P comes into closely contact with the ADF14. The scanner unit13continuously obtains an image line by line by the image sensor31from the paper sheet P transported by the ADF14, and thereby the entire image of the paper sheet P transported by the ADF14is obtained.

The paper feed cassette15is a cassette that accommodates the paper sheet P therein. The paper feed cassette15is configured to be able to supply the paper sheet P from an outside of the casing11. For example, the paper feed cassette15is configured to be able to withdraw from the casing11.

The paper discharge tray16is a tray that supports the paper sheet P discharged from the image forming apparatus1. For example, the paper discharge tray16is provided on an upper surface of the casing11.

The image forming unit17forms an image on the paper sheet P under the control of the main control unit19. For example, the image forming unit17charges the drum, forms the latent image according to the image data (print data) for printing on the charged drum, attaches toner to the latent image formed on the drum, and forms an image on the paper sheet P by transferring the toner attached to the latent image on the paper sheet P.

FIG. 3is a diagram for explaining a configuration example of the image forming unit17. For example, as shown inFIG. 3, the image forming unit17includes a drum41, an exposure device42, a developing device43, a transfer belt44, one pair of transfer rollers45, and one pair of fixing rollers46.

The drum41is a photoconductive drum formed in a cylindrical shape. The drum41is provided to be in contact with the transfer belt44. A surface of the drum41is uniformly charged by a charging charger (not shown). In addition, the drum41rotates at a constant speed by a drive mechanism (not shown) in a rotation direction R.

The exposure device42forms the electrostatic latent image on the charged drum41. The exposure device42irradiates a surface of the drum41with light by a light emitting element or the like according to the print data and thereby forms the electrostatic latent image on the surface of the drum41. As shown inFIG. 3, the exposure device42includes a light emitting unit51, a lens mirror array52, a protective glass53, a light blocking body54, a casing55, and a substrate56.

The light emitting unit51has a configuration in which the light emitting elements emitting light according to an electric signal (image signal) are arranged in a line shape. An arrangement direction of the light emitting elements in the light emitting unit51is referred to as a main scan direction M2. The main scan direction M2is a direction orthogonal to a light axis of a plurality of light emitting elements and in parallel with a rotation axis of the drum41. The main scan direction M2may be the same as the main scan direction M1of the scanner unit13, or may be a different direction from the main scan direction M1. The light emitting element of the light emitting unit51emits light of a wavelength capable of forming the latent image on the charged drum41. For example, the light emitting element is an LED or an OLED which emits divergent light which turns on and off each LED according to the image signal.

The lens mirror array52is an optical component which forms an image by light emitted from the light emitting element of the light emitting unit51on a surface of the drum41. The lens mirror array52has the same configuration as the lens mirror array32provided in the scanner unit13. A range in which an image is formed by light from the lens mirror array52is a rectangular region on a surface of the drum41. That is, the lens mirror array52forms an image according to light from the plurality of light emitting elements in the light emitting unit51within the rectangular region on the surface of the drum41. A detailed configuration of the lens mirror array52will be described below.

The protective glass53is provided between the lens mirror array52and the drum41. The protective glass53is a glass for protecting the lens mirror array52. The protective glass53prevents the toner and dust from adhering to the lens mirror array52.

The light blocking body54is provided between the lens mirror array52and the light emitting unit51. The light blocking body54is a member for blocking light. For example, the light blocking body54is a member applied with a light blocking material on a surface thereof. The light blocking body54blocks a part of light emitted from the light emitting unit51. For example, the light blocking body54blocks light passing through a position which is separated by a predetermined distance or more from a light axis of the light emitting element of the light emitting unit51in a direction orthogonal to the light axis of the light emitting element.

The casing55is a member that supports and positions the light emitting unit51, the lens mirror array52, the protective glass53, the light blocking body54, and the substrate56. In addition, the casing55includes the light blocking unit that blocks a part of the light emitted from the lens mirror array52. The light blocking unit blocks light to be the stray light when incident on the drum41, or light emitted in a direction not incident on a predetermined image formation range on the drum41from the lens mirror array52.

The substrate56is apart on which the light emitting unit51and a driver or the like for driving the light emitting unit51are mounted.

The exposure device42inputs the print data to a driver provided in the substrate56and thereby the driver emits light from the light emitting unit51. The light emitted from the light emitting unit51forms an image on the drum41by the lens mirror array52. The exposure device42continuously forms an image by the light from the light emitting unit51with respect to the drum41that is rotated, and thereby forms the latent image on the drum41.

The developing device43attaches the toner (developer) to the electrostatic latent image formed on the drum41. With this, the developing device43forms an image (toner image) of the toner on a surface of the drum41.

The drum41, the exposure device42, and the developing device43of the image forming unit17are provided for different colors such as cyan, magenta, yellow, and black. In this case, a plurality of developing devices43hold toners of different colors, respectively.

The transfer belt44is a member for receiving the toner image formed on a surface of the drum41, and transferring the toner image on the paper sheet P. The transfer belt44is moved by rotation of a roller. The transfer belt44receives the toner image formed on the drum41, and carries the received toner image to the one pair of transfer rollers45, at a position in contact with the drum41.

The one pair of transfer rollers45is configured to nip the transfer belt44and the paper sheet P. The one pair of transfer rollers45transfers the toner image on the transfer belt44to the paper sheet P.

The one pair of fixing rollers46is configured to nip the paper sheet P therebetween. The one pair of fixing rollers46is heated by a heater (not shown). The one pair of fixing rollers46applies pressure to the nipped paper sheet Pin a heated state and thereby fixes the toner image formed on the paper sheet P. That is, the one pair of fixing rollers46fixes the toner image and thereby an image is formed on the paper sheet P.

The transporting unit18transports the paper sheet P. The transporting unit18includes a transport path configured by a plurality of guides and a plurality of rollers, and a sensor that detects a transport position of the paper sheet P in the transport path. The transport path is a path through which the paper sheet P is transported. A transport roller is rotated by a motor operated under the control of a transport control unit (not shown) receiving a command of the main control unit19and thereby transports the paper sheet P along the transport path. In addition, a part of the plurality of guides is rotated by the motor operated under the control of the transport control unit and thereby switches the transport path that transports the paper sheet P.

For example, as shown inFIG. 1, the transporting unit18includes a take-in roller61, a paper feed transport path62, a paper discharge transport path63, and an inversion transport path64.

The take-in roller61feeds the paper sheet P accommodated in the paper feed cassette15to the paper feed transport path62.

The paper feed transport path62is a transport path for transporting the paper sheet P fed from the paper feed cassette15by the take-in roller61to the image forming unit17.

The paper discharge transport path63is a transport path for discharging the paper sheet P on which an image is formed by the image forming unit17from the casing11. The paper sheet P discharged by the paper discharge transport path63is discharged to the paper discharge tray16.

The inversion transport path64is a transport path for supplying the paper sheet P to the image forming unit17again, in a state where a front surface and a back surface, a leading edge and a trailing edge, and the like of the paper sheet P, are inverted, on which an image is formed by the image forming unit17.

The main control unit19controls the entirety of the image forming apparatus1. The main control unit19includes a processor of a CPU or the like, and a memory. A processor executes a program stored in the memory and thereby the main control unit19realizes various process functions. The main control unit19controls the scanner unit13and thereby obtains an image from the paper sheet P. In addition, the main control unit19controls the image forming unit17and thereby controls formation of an image with respect to the paper sheet P. For example, the main control unit19inputs the print data to the image forming unit17. The main control unit19controls the transport control unit and thereby controls transport of the paper sheet P.

Next, the lens mirror array32and the lens mirror array52will be described.

FIG. 4toFIG. 7are diagrams for explaining configuration examples of the lens mirror array32and the lens mirror array52. Since the lens mirror array32and the lens mirror array52have the same configuration, an example of the lens mirror array52used in the exposure device42will be described, in this example.

FIG. 4is a perspective view of the lens mirror array52. The lens mirror array52includes a flange unit71used for mounting the lens mirror array52and a plurality of optical elements72arranged along the main scan direction M2. The lens mirror array52is formed by injection molding using a mold in which Ni plating is performed on a blank of a mold steel and an Ni layer thereof is manufactured with a tool with R on a corner of the tool. For example, the mold has a inserts. With the mold having the inserts, a plurality of optical elements72and the flange unit71in the lens mirror array52are integrally formed. For example, the lens mirror array52is configured by a transparent resin or glass.

The flange units71are members which are provided at both ends of the lens mirror array52in the arrangement direction of the optical elements72. Since the flange unit71does not affect the optical performance of the lens mirror array52, the flange unit71can be touched with hands when attaching to the exposure device42or the like.

The optical element72has a function of forming an image by incident light on an image formation target. For example, the optical element72forms an image by light from the plurality of light emitting elements of the light emitting unit51in an image formation range.

FIG. 5is a diagram showing one optical element72cut from the lens mirror array52. In addition,FIG. 6is a diagram for explaining light when one optical element72is viewed in the main scan direction M2.FIG. 7is a diagram for explaining an example of the cross-section C-C of the lens mirror array52inFIG. 6.

The optical element72includes a first lens surface81, a first mirror surface82that reflects light incident on the first lens surface81, a second mirror surface83that reflects the light reflected by the first mirror surface82, and a second lens surface84that emits the light reflected by the second mirror surface83. The first lens surface81, the first mirror surface82, the second mirror surface83, and the second lens surface84are configured to be surface symmetry with respect to a symmetrical surface A which is a surface orthogonal to the arrangement direction of the optical elements72.

The optical element72forms an image by light from an object point O at an image formation point F. When the optical element72is formed on the lens mirror array52, the light emitting element of the light emitting unit51is positioned at the object point O, and a surface of the drum41is positioned at the image formation point F. In addition, when the optical element72is formed on the lens mirror array32, a rectangular read region on the placement surface22of the document platen12is positioned at the object point O, and a pixel of the image sensor31is positioned at the image formation point F. In addition, when the optical element72is formed on the lens mirror array32, the main scan direction M2can be read as the main scan direction M1.

The first lens surface81is a convex lens surface whose surface protrudes outward. The first lens surface81forms an intermediate inverted image of incident light. Light from a predetermined object point O is incident on the first lens surface81. For example, the first lens surface81is configured such that the light emitted from the plurality of light emitting elements of the light emitting unit51is incident thereon. Specifically, the first lens surface81is configured such that light emitted from the light emitting elements arranged within a width of two to three times in a pitch of the optical element72is incident thereon.

For example, the first lens surface81is symmetrical with respect to the symmetrical surface A, and configured as a free curved surface shape. The first lens surface81maybe a surface in which curvature of the first lens surface81when the first lens surface81is cut along a surface (for example, symmetrical surface A) orthogonal to the main scan direction M2and curvature of the first lens surface81when the first lens surface81is cut along a surface including a direction between the first lens surface81and the second lens surface84, and the main scan direction M2, are different from each other. Furthermore, the curvature of the first lens surface81when the first lens surface81is cut along the surface orthogonal to the main scan direction M2may not be constant if it is symmetrical with respect to the symmetrical surface A. Furthermore, the curvature of the first lens surface81when the first lens surface81is cut along the surface including the direction between the first lens surface81and the second lens surface84, and the main scan direction M2may not be constant. Furthermore, the curvature of the first lens surface81when the first lens surface81is cut along the surface orthogonal to the main scan direction M2may be symmetrical with respect to the symmetrical surface A, and may be changed by a predetermined change amount. Furthermore, the curvature of the first lens surface81when the first lens surface81is cut along the surface including the direction between the first lens surface81and the second lens surface84, and the main scan direction M2may be changed by a predetermined change amount. In addition, the first lens surface81may be a spherical surface.

The first mirror surface82reflects the light incident on the first lens surface81. That is, the first mirror surface82reflects the light that is incident on the first lens surface and thereby becomes convergent light, and forms the intermediate inverted image after reflection on a downstream side of a light path. The first mirror surface82reflects the light incident on the first lens surface81by the total reflection or the Fresnel reflection. The first mirror surface82is formed in a planar shape on one side of the optical element72in a direction orthogonal to the main scan direction M2.

The second mirror surface83reflects the light reflected by the first mirror surface82. That is, the second mirror surface83reflects the light that emerges from the intermediate inverted image formed after reflection by the first mirror surface82. The second mirror surface83reflects the reflected light reflected by the first mirror surface82by the total reflection or the Fresnel reflection.

For example, the second mirror surface83is formed in a rectangular shape, and curved inwardly. For example, the second mirror surface83is symmetrical with respect to the symmetrical surface A, and configured as the free curved surface shape. The second mirror surface83may be a surface in which curvature of the second mirror surface83when the second mirror surface83is cut along a surface (for example, symmetrical surface A) orthogonal to the main scan direction M2and curvature of the second mirror surface83when the second mirror surface83is cut along the surface including the direction between the first lens surface81and the second lens surface84, and the main scan direction M2, are different from each other. Furthermore, the curvature of the second mirror surface83when the second mirror surface83is cut along the surface orthogonal to the main scan direction M2may not be constant if it is symmetrical with respect to the symmetrical surface A. Furthermore, the curvature of the second mirror surface83when the second mirror surface83is cut along the surface including the direction between the first lens surface81and the second lens surface84, and the main scan direction M2may not be constant. Furthermore, the curvature of the second mirror surface83when the second mirror surface83is cut along the surface orthogonal to the main scan direction M2may be symmetrical with respect to the symmetrical surface A, and may be changed by a predetermined change amount. Furthermore, the curvature of the second mirror surface83when the second mirror surface83is cut along the surface including the direction between the first lens surface81and the second lens surface84, and the main scan direction M2, may be changed by a predetermined change amount. In addition, the second mirror surface83may be a spherical surface. In addition, the second mirror surface83may be formed in, for example, a planar shape. The second mirror surface83is formed on an opposite side to the first mirror surface82of the optical element72in the direction orthogonal to the main scan direction M2.

The second lens surface84is a convex lens surface whose surface protrudes outward. The second lens surface84forms an erect image that is an inverted image of the intermediate inverted image formed by the first lens surface81by being combined with the second mirror surface83. The light emitted from the second lens surface84is incident on a predetermined image formation point F. For example, the light emitted from the second lens surface84forms an image at a predetermined position within an image formation range on the drum41.

For example, the second lens surface84is symmetrical with respect to the symmetrical surface A, and configured as the free curved surface shape. The second lens surface84may be a surface in which curvature of the second lens surface84when the second lens surface84is cut along the surface (for example, symmetrical surface A) orthogonal to the main scan direction M2and curvature of the second lens surface84when the second lens surface84is cut along the surface including the direction between the first lens surface81and the second lens surface84, and the main scan direction M2, are different from each other. Furthermore, the curvature of the second lens surface84when the second lens surface84is cut along the surface orthogonal to the main scan direction M2may not be constant if it is symmetrical with respect to the symmetrical surface A. Furthermore, the curvature of the second lens surface84when the second lens surface84is cut along the surface including the direction between the first lens surface81and the second lens surface84, and the main scan direction M2may not be constant. Furthermore, the curvature of the second lens surface84when the second lens surface84is cut along the surface orthogonal to the main scan direction M2may be symmetrical with respect to the symmetrical surface A, and may be changed by a predetermined change amount. Furthermore, the curvature of the second lens surface84when the second lens surface84is cut along the surface including the direction between the first lens surface81and the second lens surface84, and the main scan direction M2may be changed by a predetermined change amount. In addition, the second lens surface84may be the spherical surface.

In addition, the optical element72includes one pair of first light blocking surfaces85, a fifth light blocking surface86, a second light blocking surface87, and a concave portion88formed in the second light blocking surface87.

The one pair of first light blocking surfaces85are provided at positions nipping the symmetrical surface A in the main scan direction M2. That is, the one pair of first light blocking surfaces85are disposed along the main scan direction M2at positions separated from the symmetrical surface A by a predetermined distance. The first light blocking surfaces85share sides thereof with the first mirror surface82. The first light blocking surface85forms an obtuse angle with the first mirror surface82, and forms an acute angle toward an incident side of the symmetrical surface A.

In addition, as shown inFIG. 7, the first light blocking surface85includes a light blocking layer89that is formed by applying ink (for example, UV ink containing light blocking material such as carbon black or black pigment) having a high light blocking property, with approximately the same refractive index as the lens mirror array, and blocks light. The first light blocking surface85includes the light blocking layer89, and thereby light is prevented from being reflected from the first light blocking surface85to an inside of the optical element72and emitted outward.

In addition, the above-described first light blocking surface85is formed in each of the optical elements72, and thereby a groove whose both sides are configured as the first light blocking surface85between two optical elements72, is formed. The light blocking layer89is also formed on a bottom92of the groove. With this, light is prevented from being reflected from the bottom92of the groove to the inside of the optical element72and emitted outward.

FIG. 7is a diagram viewing the cross-section C-C of the lens mirror array52taken line VII-VII ofFIG. 6in a direction in parallel with the first mirror surface82and orthogonal to the main scan direction M2. As described above, since the lens mirror array52is formed by the injection molding, a curved surface is formed on a boundary portion. For example, as shown inFIG. 7, a curved surface90is formed on the boundary portion between the first mirror surface82and the first light blocking surface85.

When the UV ink before curing covers the entirety of the curved surface90and an amount of the ink reaching the first mirror surface82is applied, there is a possibility that the UV ink spreads on the first mirror surface82. For this reason, the UV ink is applied by an amount which does not cover the entirety of the curved surface90. That is, the light blocking layer89is formed in a range which covers at least the entirety of the first light blocking surface85and does not reach the entirety of the curved surface90so as to prevent the UV ink from adhering to the first mirror surface82. In addition, as shown inFIG. 7, since the first light blocking surface85and the first mirror surface82are formed to be an obtuse angle, it is possible to easily peel the lens mirror array52from the mold.

The optical elements72may continuously be implemented on an end side approaching an emission side of the first mirror surface82, and may further include a fourth light blocking surface91forming an obtuse angle with the first mirror surface82. The light blocking layer89is also formed by applying the UV ink on the fourth light blocking surface91similar to the first light blocking surface85. By providing the light blocking layer89, the fourth light blocking surface91blocks light that is reflected by the first mirror surface82and progresses at a position separated from the symmetrical surface A by a predetermined distance, and light that is reflected by the first mirror surface82and directly progresses to the second lens surface84.

The fifth light blocking surface86is a surface inclined to a symmetrical surface A side with respect to the first light blocking surface. For example, the fifth light blocking surface86is configured as apart of the concave portion that is recessed in a direction orthogonal to the first light blocking surface85from the first light blocking surface85. That is, the fifth light blocking surface86is configured as a mountain shape surface together with the first light blocking surface85.

The fifth light blocking surface86may be formed as a flat surface or a curved surface. For example, the fifth light blocking surface86is configured as a curved surface having a curvature in one direction. That is, the center of the curvature of the fifth light blocking surface86is formed so as to be an arc of a predetermined curvature positioned inside the optical element72with respect to the first light blocking surface85, when cutting along a surface in parallel with the first mirror surface82. That is, the fifth light blocking surface86is configured as a shape corresponding to a part of a cylindrical shape. In addition, the center of the curvature of the fifth light blocking surface86may be formed so as to be an arc that is positioned inside the optical element72with respect to the first light blocking surface85, and has a large curvature as approaching a first mirror surface82side, when cutting along the surface in parallel with the first mirror surface82. That is, the fifth light blocking surface86may be formed as a shape corresponding to a part of a truncated cone shape.

The light blocking layer89is also formed by applying the UV ink on the fifth light blocking surface86similar to the first light blocking surface85. By providing the light blocking layer89, the fifth light blocking surface86blocks light progresses at a position separated from the symmetrical surface A by a predetermined distance.

For example, a portion between the fifth light blocking surface86and the fourth light blocking surface91is configured as a surface forming an obtuse angle with respect to the first mirror surface82, and in parallel with the first light blocking surface85. In addition, the light blocking layer89may also be provided on the surface. In addition, if the surface forms an obtuse angle with the first mirror surface82, and forms an acute angle toward an incident side with respect to the symmetrical surface A, any surface may be used.

The second light blocking surface87is formed on a side approaching the second lens surface84with respect to the first mirror surface82, on the same side as a side on which the first mirror surface82of the optical element72is provided in the direction orthogonal to the main scan direction M2. For example, the second light blocking surface87is formed in a planar shape. For example, the second light blocking surface87is formed across the second lens surface84from a side opposite to the first mirror surface82of the fourth light blocking surface91. That is, the second light blocking surface87is configured to share a side thereof with the fourth light blocking surface91. In addition, the second light blocking surface87is formed such that a surface is continuous from the bottom92of the groove formed between two optical elements72. In addition, the second light blocking surface87forms an acute angle toward the second mirror surface83with respect to the symmetrical surface A between the second mirror surface83and the second lens surface84.

In addition, the light blocking layer89is also formed by applying the UV ink on the second light blocking surface87. Since the light blocking layer89is provided on the second light blocking surface87, it is possible to emit light into the air without reflecting on the first mirror surface82, and prevent the light incident on the second light blocking surface87from entering a structure configuring the optical element72again.

The concave portion88is a portion formed by being recessed in a direction orthogonal to the second light blocking surface87from the second light blocking surface87. That is, the concave portion88is provided on an emission side of the first mirror surface82in a direction between the first lens surface81and the second lens surface84.

The concave portion88is formed between the two optical elements72in the main scan direction M2. That is, the concave portion88is formed over adjacent two optical elements72. As described above, the concave portion88is formed in each of the optical elements72such that the third light blocking surfaces93that are one pair of light blocking surfaces facing each other for each the concave portion88, are formed.

The third light blocking surface93is a surface inclined with respect to the main scan direction M2. That is, the third light blocking surface93is a surface forming an angle with respect to the main scan direction M2. For example, the third light blocking surface93is formed in a planar shape.

In addition, for example, a bottom94between two third light blocking surfaces93of the concave portion88is formed to be continuous on the bottom92of the groove formed between the two optical elements72.

In addition, the light blocking layer89is formed by also applying the UV ink on each surface of the concave portion88. By the third light blocking surface93on which the light blocking layer89is formed, since a progressing direction of light includes a component in a direction along the main scan direction M2, the concave portion88blocks light entering other optical elements72.

FIG. 8is a diagram for explaining a light path of light incident on the lens mirror array52. For example, light incident on the first lens surface81from the object point O along the symmetrical surface A of the optical element72that is the lens mirror array52is reflected in order of the first mirror surface82and the second mirror surface83, and emitted from the second lens surface84to the image formation point F of the optical element72.

In the lens mirror array52in which a plurality of optical elements72are integrally formed, there is a case where a part of light which enters from the first lens surface81and passes through a position separated from the symmetrical surface A by a predetermined distance, is incident on the curved surface90formed on the boundary portion between the first mirror surface82and the first light blocking surface85. Since light incident on the curved surface90is reflected in a direction corresponding to inclination of a place where the light reaches on the curved surface90, there is a possibility that the reflected light progresses in various directions and becomes the stray light entering other optical elements72.

However, the optical element72includes the fifth light blocking surface86inclined to the symmetrical surface A side with respect to the first light blocking surface85. With this, as light passing through a light path L1shown inFIG. 8, the optical element72can block a part of light progressing at an angle to be incident on the curved surface90. As a result, the optical element72can decrease the stray light.

In addition, the optical element72is provided on an emission side of a first mirror surface82, and includes the third light blocking surface93that forms an angle with respect to the main scan direction M2. With this, as light passing through a light path L2shown inFIG. 8, the optical element72can block a part of light progressing at an angle that is incident on other optical elements72by reflecting on the curved surface90. As a result, the optical element72can decrease the stray light.

As described above, the lens mirror array52is configured by arranging a plurality of optical elements72including the first lens surface81on which light is incident, the first mirror surface82that reflects light incident on the first lens surface81, the second mirror surface83that reflects the light reflected by the first mirror surface82, and the second lens surface84that emits the light reflected by the second mirror surface83. Furthermore, the optical element72includes the one pair of first light blocking surfaces85that are formed to share sides thereof with the first mirror surface82at a position nipping the symmetrical surface A defined by the first lens surface81and the second lens surface84in the arrangement direction of the optical elements72of the lens mirror array52, the fifth light blocking surface86inclined on the symmetrical surface A side with respect to the first light blocking surface85, and the light blocking layer89formed over the first light blocking surface85and the fifth light blocking surface86. With the configuration, the lens mirror array52can block a part of light incident on the curved surface90formed between the first mirror surface82and the first light blocking surface85, and a part of light reflected from the curved surface90. As a result, the lens mirror array52can decrease light to be the stray light by reflecting on the curved surface90.

In addition, a section surface in a surface in parallel with the first mirror surface82of the fifth light blocking surface86is formed as an arc of curvature whose center is positioned on the symmetrical surface A side of the first light blocking surface85. With this, it is possible to increase the inclination with respect to the symmetrical surface A of the fifth light blocking surface86. With the configuration, the lens mirror array52can block more light incident on the curved surface90. As a result, the lens mirror array52can decrease light to be the stray light by reflecting on the curved surface90.

In addition, the first light blocking surface85is configured to form an acute angle toward an emission side of the symmetrical surface A. With this, an interval between the one pair of first light blocking surfaces85can be narrower as it approaches the incident side. As a result, it is possible to limit a progress direction of light incident on the curved surface90. In addition, it is possible to increase a region facing the symmetrical surface A of the fifth light blocking surface86continuing to the first light blocking surface85. As a result, the lens mirror array52can decrease light to be the stray light by reflecting on the curved surface90.

In order to simplify a step of implementing a mold for the injection molding of the lens mirror array52, it is desirable that a curvature radius of the fifth light blocking surface86is configured with a curvature radius of ⅛ or more of the widest interval between the one pair of first light blocking surfaces85in the optical element72. According to the configuration, a tool (for example, front milling cutter or end mill) having a diameter corresponding to the curvature radius of the fifth light blocking surface86is reciprocated twice in a direction approximately in parallel with the symmetrical surface A and the first mirror surface82such that it is possible to form a structure of a mold for the injection molding of the first light blocking surface85, the fifth light blocking surface86, and the fourth light blocking surface91. That is, since the curvature radius of the fifth light blocking surface86is configured with the curvature radius of ⅛ or more of the widest interval between the one pair of first light blocking surfaces85in the optical element72, it is possible to decrease a manufacturing time of the mold. A small curvature radius of the fifth light blocking surface86has a large light blocking effect in the stray light compared to a large curvature radius. For this reason, it is desirable that the curvature radius of the fifth light blocking surface86is a value, as small as possible, of ⅛ or more of the widest interval between the one pair of first light blocking surfaces85in the optical element72.

It is further desirable that the curvature radius of the fifth light blocking surface86is configured with a curvature radius of ¼ or more of the widest interval between the one pair of first light blocking surfaces85in the optical element72. According to the configuration, a tool (for example, front milling cutter or end mill) having a diameter corresponding to the curvature radius of the fifth light blocking surface86is reciprocated once in the direction approximately in parallel with the symmetrical surface A and the first mirror surface82such that it is possible to form the structure of the mold for the injection molding of the first light blocking surface85, the fifth light blocking surface86, and the fourth light blocking surface91. That is, since the curvature radius of the fifth light blocking surface86is configured with the curvature radius of ¼ or more of the widest interval between the one pair of first light blocking surfaces85in the optical element72, it is possible to further decrease a manufacturing time of the mold.

Furthermore, in order to continuously manufacture a surface of the first mirror surface82, the curvature radius of the fifth light blocking surface86needs to be half or less of the width of the narrowest portion of the first mirror surface. When the condition is not satisfied, a tool is moved to avoid a narrow place by separating the tool before or after the narrow place once from the mold, and the manufacturing is performed by lowering the tool to the same height again. In this manner, a step is formed on the first mirror surface82, and optical performance is deteriorated.

In addition, the optical element72includes the second light blocking surface87that is on the same side as a side on which the first mirror surface82of the optical element72is provided in the direction orthogonal to the main scan direction M2, and formed on a side of the first mirror surface82close to the second lens surface84. Furthermore, the lens mirror array52includes the concave portion88formed by recessing in a direction orthogonal to the second light blocking surface87over adjacent two optical elements72. The lens mirror array52includes the third light blocking surfaces93that are the one pair of light blocking surfaces facing each other for each the concave portion88and inclined with respect to the main scan direction M2, and the light blocking layer89formed over the second light blocking surface87and the third light blocking surface93. With the configuration, the lens mirror array52can block a part of light progressing at an angle which enters other optical elements72by reflecting on the curved surface90. As a result, the optical element72can decrease the stray light.

In addition, the concave portion88configuring the third light blocking surface93is formed at a position separated from the symmetrical surface A by a predetermined distance in the arrangement direction of the optical elements72over adjacent two optical elements72. For this reason, it is possible that light contributing to the image formation, which is not the stray light, is not blocked by the third light blocking surface93, or the amount of the light to be blocked is negligible.

In addition, the bottom92between the two first light blocking surfaces85facing each other of the lens mirror array52, and the bottom94of the concave portion88are configured as continuous surfaces. That is, the bottom94of the concave portion88is configured as a continuous surface with the bottom92that is a surface between the two first light blocking surfaces85facing each other in the adjacent optical elements72. By adopting such a configuration, when the UV ink is applied on the light blocking surface87, the UV ink spreads on the light blocking surface85and the bottom92without a break. As a result, it is possible to form a light blocking layer without defects while reducing the number of processes for forming the light blocking layer, and it is possible for the optical element72to decrease the stray light.

Second Embodiment

In the first embodiment, the optical element72is described as a configuration in which one pair of fifth light blocking surfaces86is provided between the first lens surface81and the fourth light blocking surface91. However, the embodiment is not limited to the configuration. According to an optical design of the lens mirror array52, there is a possibility that the stray light occurs by entering of the light in a wide range of the curved surface90. Since the optical element72includes a plurality of pairs of the fifth light blocking surfaces86between the first lens surface81and the fourth light blocking surface91, it is possible to block light progressing in a direction entering the wide range of the curved surface90.

FIG. 9andFIG. 10are diagrams showing a configuration example of apart of a lens mirror array on which optical elements including a plurality of pairs of the second light blocking surfaces are arranged.FIG. 9is a diagram showing a configuration example of a part of a lens mirror array52A including two pairs of fifth light blocking surfaces86A.FIG. 10is a diagram for explaining a configuration example of a part of a lens mirror array52B including three pairs of fifth light blocking surfaces86B.

As shown inFIG. 9, the lens mirror array52A includes a plurality of optical elements72A arranged in the main scan direction. The optical element72A includes the first lens surface81, the first mirror surface82, the second mirror surface83, the second lens surface84, two pairs of first light blocking surfaces85A, and the two pairs of fifth light blocking surfaces86A, the second light blocking surface87, the concave portion88formed on the second light blocking surface87, the fourth light blocking surface91, and the third light blocking surface93that is a surface of the concave portion88.

The two pairs of first light blocking surfaces85A are provided at a position nipping the symmetrical surface A in the main scan direction M2and are surfaces which form an obtuse angle with the first mirror surface82and form an acute angle toward the incident side with respect to the symmetrical surface A, similar to the first light blocking surface85.

The two pairs of fifth light blocking surfaces86A are surfaces inclined to the symmetrical surface A side with respect to the first light blocking surfaces85A similar to the fifth light blocking surface86.

A surface is continuous in the order of the first light blocking surfaces85A, the fifth light blocking surface86A, the first light blocking surfaces85A, and the fifth light blocking surface86A, toward the fourth light blocking surface91from the first lens surface81. In addition, an interval between the fifth light blocking surfaces86A forming a pair is formed to be wide as it is close to the incident side.

In addition, as shown inFIG. 10, the lens mirror array52B includes a plurality of optical elements72B arranged in the main scan direction. The optical element72B includes the first lens surface81, the first mirror surface82, the second mirror surface83, the second lens surface84, three pairs of first light blocking surfaces85B, the three pairs of fifth light blocking surfaces86B, the second light blocking surface87, the concave portion88formed on the second light blocking surface87, the fourth light blocking surface91, and the third light blocking surface93that is a surface of the concave portion88.

The three pairs of first light blocking surfaces85B are provided at a position nipping the symmetrical surface A in the main scan direction M2, and are surfaces forming an obtuse angle with the first mirror surface82, and an acute angle toward the incident side with respect to the symmetrical surface A, similar to the first light blocking surface85and the first light blocking surfaces85A.

The three pairs of fifth light blocking surfaces86B are surfaces inclined to the symmetrical surface A side with respect to the first light blocking surface85B, similar to the fifth light blocking surface86and the fifth light blocking surface86A.

A surface is continuous in the order of the first light blocking surface85B, the fifth light blocking surface86B, the first light blocking surface85B, the fifth light blocking surface86B, the first light blocking surface85B, and the fifth light blocking surface86B toward the fourth light blocking surface91from the first lens surface81. In addition, an interval between the fifth light blocking surfaces86B forming a pair is formed to be wide as it is close to the incident side.

According to the configuration, the lens mirror array52can block the light reflected by the curved surface90by the fifth light blocking surface86A or the fifth light blocking surface86B on the emission side. As a result, the optical element72can decrease the stray light.

In the embodiment, the image sensor31is configured by arranging the pixels for converting the light into the electric signal (image signal) in a line shape. However, the embodiment is not limited to the configuration. The image sensor31may be configured by arranging the pixels for converting the light into the electric signal (image signal) in a plurality of rows in a line shape. In this case, the scanner unit13includes a plurality of lens mirror arrays32corresponding to respective rows of the pixels of the image sensor31in order to form an image by the light from the reading range on the pixels of the respective rows of the image sensors31. Also, the scanner31may include one lens mirror array32that forms an image on a region including the pixels of the respective rows of the image sensor31in order to form an image by the light from the reading range on the pixels of the respective rows of the image sensor31. In addition, the image sensor31may have a configuration in which pixels having sensitivities of light of different wavelengths are arranged for each row. Furthermore, the image sensor31may have a configuration in which pixels having sensitivities of light of wavelengths of red, green, and blue colors are arranged in a zig-zag pattern over two rows.

In addition, the embodiment is described that the light emitting unit51is configured by arranging the light emitting elements emitting the light according to the electric signal (image signal) in a line shape. However, the embodiment is not limited to the configuration. The light emitting unit51may be configured by arranging the light emitting elements emitting the light according to the electric signal (image signal) in a plurality of rows in a line shape. In this case, the exposure device42includes a plurality of lens mirror arrays52corresponding to the respective rows of the light emitting elements of the light emitting unit51in order to form an image by the light from the respective rows of the light emitting elements on the surface of the drum41. Also, the exposure device42may include one lens mirror array52that forms an image by the light from a region including the respective rows of the light emitting elements of the light emitting unit51on the surface of the drum41in order to form an image by the light from respective rows of the light emitting elements on the surface of the drum41. In addition, the light emitting unit51may have a configuration in which the light emitting elements emitting light of different wavelength for each row are arranged. Furthermore, the light emitting unit51may have a configuration in which the light emitting elements emitting light of wavelengths of red, green, and blue colors are arranged in the zig-zag pattern over two rows.

In addition, in the embodiment, as an example of the image forming apparatus using the lens mirror array, a printer forming an image by the toner on the paper sheet, and a scanner forming an image by reading the reflected light from the paper sheet are exemplified. However, the embodiment is not limited to the configuration. If an image is formed by the light from the reading range on an image formation target, the lens mirror array may be used for anything. For example, the lens mirror array may be used in a silver halide print apparatus which forms an image by forming an image by light from a light emitting unit in which OLED light sources emitting a plurality of different colors are arranged in a two-dimensional manner, on a surface of a photoconductive material.