JP2013024961A - Lens eye, lens unit, led head, exposure apparatus, image forming apparatus, and reading apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the amount of light of an optical system.SOLUTION: A lens eye comprises: a plurality of lenses arranged in two lines; and the plurality of lenses are adjacent to each other in a longer direction and a shorter direction. The lenses adjacent in the shorter direction are arranged in line in a first boundary area extending in the longer direction, and each of the lenses has an optical axis in the first boundary area.

Description

  The present invention relates to a lens array, a lens unit, an LED head, an exposure apparatus, an image forming apparatus, and a reading apparatus.

  Conventional lens arrays are used to form an image of a read original on an electrophotographic image forming apparatus using an LED head in which a plurality of LEDs (light emitting diodes) are linearly arranged, or on a light receiving portion in which a plurality of light receiving elements are linearly arranged. It is used as an optical system that can form an erecting equal-magnification image of an object in a line on a reading device such as a scanner or a facsimile.

  In this lens array, a plurality of microlenses are arranged in two substantially linear lines so as to form an erecting equal-magnification image of an object, and the arrangement interval between two adjacent microlenses is arranged between the microlenses There is an optical system that forms an image with high resolution so as to be smaller than the arrangement interval between two microlenses adjacent in the direction (see, for example, Patent Document 1).

JP 2008-92006 A (paragraph “0031” to paragraph “0037”, FIG. 1)

However, in the conventional technology described above, in order to improve the resolution of the image forming apparatus, it is necessary to reduce the LED elements of the LED head in accordance with the arrangement interval of the microlenses and increase the mounting density. Since the amount of light emitted from the LED element decreases, there is a problem that the amount of light in the optical system needs to be increased, and in the reading device, the amount of light in the optical system is increased in order to keep power consumption of the illumination device that illuminates the document low. There is a problem that it is necessary.
An object of the present invention is to solve such a problem and to increase the amount of light of an optical system.

  Therefore, the present invention provides a lens array in which a plurality of lenses are arranged in two rows, and has a plurality of lenses adjacent in the longitudinal direction and a plurality of lenses adjacent in the lateral direction, and is adjacent in the lateral direction. The matching lenses are continuous in a first boundary region extending in a longitudinal direction, and each of the lenses has an optical axis in the first boundary region.

  According to the present invention as described above, an effect that the amount of light of the optical system can be increased is obtained.

Exploded perspective view of the lens unit in the first embodiment 1 is a schematic diagram showing the configuration of a printer in a first embodiment. Schematic side view of the LED head in the first embodiment Sectional drawing of the LED head in a 1st Example The top view of the 1st lens board in a 1st Example The top view of the light-shielding plate in 1st Example Sectional drawing of the lens unit in 1st Example Sectional drawing of the lens unit in 1st Example Schematic which shows the structure of the reader in 2nd Example. Schematic which shows the structure of the read head of the reader in 2nd Example. Schematic which shows the structure of the read head of the reader in 2nd Example.

  Hereinafter, embodiments of a lens array, a lens unit, an LED head, an exposure apparatus, an image forming apparatus, and a reading apparatus according to the present invention will be described with reference to the drawings.

A printer as an image forming apparatus according to this embodiment will be described with reference to a schematic diagram illustrating a configuration of the printer according to the first embodiment shown in FIG.
In FIG. 2, a printer 100 forms an image on a print medium based on image data with toner made of a resin containing a pigment as a color material.

The printer 100 is provided with a paper feed cassette 60 that stores paper 101 as a printing medium, and includes a paper feed roller 61 that takes out the paper 101 from the paper feed cassette 60, and a transport roller 62 that feeds and transports the paper 101. , 63 are arranged.
The printer 100 in this embodiment is a color electrophotographic system, and a photosensitive drum 41 as an electrostatic latent image carrier that forms an image of each color of yellow, magenta, cyan, and black as an image forming unit in the printer 100. The electrostatic latent image formed on the photosensitive drum 41 is developed with toner, and a developing device 5 that forms a toner image, and a toner cartridge 51 that supplies the toner to the developing device 5 are provided along the conveyance path of the paper 101. They are arranged side by side.

Further, a charging roller 42 for supplying electric charges to the surface of the photosensitive drum 41 and an LED head 3 as an optical head are disposed so as to face the surface of the photosensitive drum 41, and the LED head 3 is charged by the charging roller 42. An electrostatic image is formed by selectively irradiating light on the surface of the photosensitive drum 41 charged in step S4 based on image data.
Further, a transfer roller 80 formed on the photosensitive drum 41 and transferring a toner image, which is an image obtained by visualizing an electrostatic latent image with toner, onto the paper 101 sandwiches a transfer belt 81 that conveys the paper 101 at the transfer portion. The cleaning blade 43 is disposed so as to face the photosensitive drum 41 and removes the toner remaining on the surface of the photosensitive drum 41 after the sheet 101 passes through the transfer portion. Are arranged.

  A fixing device 9 for fixing the toner image formed on the paper 101 with heat and pressure is disposed downstream of the transfer unit, and the conveying roller 64 that conveys the paper 101 that has passed through the fixing device 9 and the conveying roller 64. A discharge roller 65 that discharges the sheet 101 on which the conveyed paper 101 on which the image is formed is stored is disposed.

  A predetermined voltage is applied to the charging roller 42 and the transfer roller 80 by a power source (not shown). The transfer belt 81, the photosensitive drum 41, and each roller are rotationally driven by a motor (not shown) and a gear that transmits driving (not shown). Furthermore, a power source and a control device are connected to the developing device 5, the LED head 3, the fixing device 9, and each motor (not shown).

The printer 100 has an external interface that receives print data from an external device, and forms an image on a print medium based on the print data received by the external interface.
The printer 100 configured as described above includes a control unit that stores a control program in a storage unit such as a memory and controls the whole based on the control program, and a control unit as a calculation unit.

FIG. 3 is a schematic side view of the LED head in the first embodiment.
In FIG. 3, a lens unit 1 is disposed on an LED head 3 as an exposure apparatus. The lens unit 1 is fixed to the LED head 3 by a holder 34. The LED elements 30 are light emitting units, and a plurality of LED elements 30 are arranged in a substantially straight line to constitute an LED array 300. The arrangement direction of the LED elements 30 is the Y-axis direction (the horizontal direction in FIG. 3). The lens unit 1 is long and is arranged in the Y-axis direction (horizontal direction in FIG. 3) so that the longitudinal direction of the lens unit 1 is parallel to the LED array 300.

Reference numeral 41 denotes a photosensitive drum on which an electrostatic latent image is formed, and AXR denotes a rotating shaft of the photosensitive drum 41. The rotational axis AXR of the photosensitive drum 41 is arranged in the Y-axis direction (horizontal direction in FIG. 3) so as to be parallel to the longitudinal direction of the LED array 300 and the lens unit 1.
The lens unit 1 is provided with a plurality of microlenses, and the optical axes of the microlenses of the lens unit 1 are arranged in the Z direction (vertical direction in FIG. 3).

FIG. 4 is a sectional view of the LED head in the first embodiment. 4 is a cross-sectional view taken along line AA in FIG.
In FIG. 4, when the direction perpendicular to both the longitudinal direction of the lens unit 1 and the optical axis direction of the micro lens of the lens unit 1 is the width direction of the lens unit 1, the width direction of the lens unit 1 is the X-axis direction (FIG. 4). In the horizontal direction). Assuming that the center of the lens unit 1 in the width direction of the lens unit 1 is CL, the rotation axis AXR of the LED element 30 and the photosensitive drum 41 is arranged on a straight line with the center CL extrapolated.

Further, the optical axis of the micro lens of the lens unit 1 is arranged so as to be in the Z direction (vertical direction in FIG. 4). The LED element 30 and the driver IC 31 are disposed on the wiring board 33. The LED element 30 and the driver IC 31 are connected by a wire 32.
In this embodiment, the LED head 3 has a resolution of 1200 dpi (dot per inch), and 1200 LED elements 30 of the LED array 300 are arranged per inch (1 inch is about 25.4 mm). That is, the arrangement pitch PD of the LED elements 30 is 0.02117 mm.

FIG. 1 is an exploded perspective view of the lens unit in the first embodiment.
In FIG. 1, the lens unit 1 includes two lens arrays and a light shielding member. 11a is a first lens plate as a lens array on the object plane side, and 11b is a second lens plate as a lens array on the imaging side. Reference numeral 21 denotes a light shielding plate as a light shielding member.

  The first lens plate 11a and the second lens plate 11b are arranged to face each other with the light shielding plate 21 in between. The first lens plate 11a has first micro lenses 12a arranged in two rows as a first lens row 13a and a second lens row 14a, and the second lens plate 11b has a second micro lens. The lenses 12b are arranged in two rows as a first lens row 13b and a second lens row 14b. The optical axes AXL of the first microlens 12a and the second microlens 12b are arranged in the Z direction (vertical direction in FIG. 5).

The light shielding plate 21 has an aperture 22 as a stop, and the aperture 22 is arranged along the longitudinal direction of the lens unit 1.
The arrangement intervals of the first microlens 12a and the second microlens 12b are the same, and are arranged so that their optical axes AXL coincide.
Thus, the lens unit 1 includes a lens group including two microlenses (first lens plate 11a and second lens plate 11b) and a diaphragm (light-shielding plate 21) arranged so that their optical axes coincide with each other. Are arranged in a substantially straight line in a direction perpendicular to the optical axis.

FIG. 5 is a plan view of the first lens plate in the first embodiment, and the Y-axis direction (vertical direction in the drawing) is the longitudinal direction of the lens plate.
In FIG. 5, a plurality of first microlenses 12a are arranged in a staggered manner in two rows on the first lens plate 11a. Assuming that one row of the first microlenses 12a arranged on the first lens plate 11a is a first lens row 13a and the other row of the first microlenses 12a is a second lens row 14a, The arrangement direction of the first microlenses 12a in the first lens array 13a and the second lens array 14a is the longitudinal direction of the first lens plate 11a.

  A first boundary region 15 is formed between the first microlens 12a in the first lens array 13a and the first microlens 12a in the second lens array 14a, and the first lens. A second boundary region 16 is formed between the adjacent first microlenses 12a in each of the row 13a and the second lens row 14a.

  The first microlens 12a in the first lens array 13a and the first microlens 12a in the second lens array 14a are continuous in the first boundary region 15, and the first lens array 13a. The adjacent first microlenses 12a in each of the second lens rows 14a are continuous in the second boundary region 16.

  The optical axis AXL of the first microlens 12a is disposed in the first boundary region 15, and is preferably disposed on a substantially center line CL in the width direction (X-axis direction in the drawing) of the lens unit 1. In the present embodiment, the optical axis AXL of the first microlens 12a will be described as being disposed on the center line CL in the width direction (X-axis direction in the drawing) of the lens unit 1.

The arrangement interval (interval of the optical axis AXL) of the first microlenses 12a in the first lens array 13a is (2 × PY), and the first microlenses in the second lens array 14a. The arrangement interval of 12a is (2 × PY).
In addition, the arrangement interval between the first microlenses 12a in the adjacent first lens rows 13a and the first microlenses 12a in the second lens rows 14a is PY.

The first microlens 12a is in contact with the adjacent first microlens 12a at the boundary and is continuously arranged without a gap. That is, the radius RLY in the arrangement direction of the first microlenses 12a is equal to the lens arrangement interval PY.
The radius of the first microlens 12a is RLY in the arrangement direction of the microlenses, and RLX in the width direction of the lens unit 1 (X-axis direction in the drawing: horizontal direction in the drawing). At this time, radius RLX> radius RLY.

  The first microlens 12a in the first lens array 13a and the first microlens 12a in the second lens array 14a in the second lens array 14a are the first microlenses in the first lens array 13a. One microlens 12a is rotated 180 degrees with the optical axis AXL of the first microlens 12a in the second lens array 14a as the rotation axis.

  The configuration of the second lens plate 11b shown in FIG. 1 is the same as the configuration of the first lens plate 11a described above, and is equivalent to the configuration in which the first microlens 12a is replaced with the second microlens 12b. It is.

The first lens plate 11a and the second lens plate 11b are made of a material that transmits the light beam of the light emitting unit. The first lens plate 11a and the second lens plate 11b of the present embodiment use an optical resin (trade name: ZEONEX (registered trademark) E48R, manufactured by Nippon Zeon Co., Ltd.), which is a cycloolefin resin, A plurality of microlenses were integrally molded by an injection molding method.
By configuring each curved surface of the first microlens 12a and the second microlens 12b with a rotationally symmetric high-order aspherical surface expressed by Formula 1, high resolution can be obtained.

  The function Z (r) represents the direction from the object plane of the lens unit 1 to the imaging plane as a positive number with the vertex of each curved surface of the first microlens 12a and the second microlens 12b as the origin. Further, r represents a coordinate in the radial direction with the direction parallel to the optical axis of the microlens as an axis, and has a relationship of Formula 2 with respect to each coordinate in the X axis and Y axis directions shown in each drawing.

  In Equation 1, Cnm represents a radius of curvature, Anm represents a fourth-order coefficient of the aspheric coefficient, Bnm represents a sixth-order coefficient of the aspheric coefficient, n and m are 1 or 2, and n = 1 is the first microlens. 12a and n = 2 indicate the second microlens 12b, m = 1 indicates a lens surface on the object plane side, and m = 2 indicates a lens surface on the image plane side.

FIG. 6 is a plan view of the light shielding plate in the first embodiment. The Y-axis direction (vertical direction) in the figure is the longitudinal direction of the light shielding plate 21, and the X-axis direction (horizontal direction) in the figure is a direction orthogonal to the longitudinal direction of the light shielding plate 21.
In FIG. 6, CL indicates a center line in the lens unit width direction (X-axis direction in the drawing) of the light shielding plate 21. The light shielding plate 21 has a plurality of openings 22 through which light incident on the microlens passes.

  The interval in the microlens array direction of the openings 22 matches the array interval of the first lenses 12a shown in FIG. 5, and the position of the opening 22 in the microlens array direction (coordinates in the Y-axis direction in the figure) is 5 coincides with the position of the first microlens 12a in the microlens array direction (coordinates in the Y-axis direction in the figure).

  The opening 22 cuts a circle with a radius RAX along a straight line parallel to the width direction (X-axis direction in the drawing) of the lens unit and at a distance RAY from the center (AXL) of the circle with the radius RAX. It is a shape cut by a straight line parallel to (in the Y-axis direction in the figure) and at a distance (TB / 2) from the center (AXL) of a circle having a radius RAX. At this time, radius RAX> distance RAY.

  The position of the opening 22 in the arrangement direction of the microlenses (the coordinate in the Y-axis direction in the figure) is arranged to coincide with the optical axis AXL. The optical axis AXL is disposed on the center line CL of the light shielding plate 21. That is, since the optical axis AXL does not coincide with the opening 22, the light beam emitted from the object and coincident with the optical axis AXL is shielded by the light shielding plate 21.

Therefore, the light shielding plate 21 is formed so as to shield the first region 15 and the second region 16 shown in FIG.
The light shielding plate 21 is formed of a material that shields light from the light emitting portion, and in this embodiment, the light shielding plate 21 is formed by injection molding using polycarbonate.

Next, details of the lens unit will be described with reference to FIG.
FIG. 7 is a cross-sectional view of the lens unit in the first embodiment, that is, a cross-sectional view of the lens unit 1 and the plane of the object plane OP and the imaging plane IP perpendicular to the arrangement direction of the microlenses and including the optical axis AXL. FIG. 7 is a cross-sectional view of the lens unit 1 taken along a line AA in FIGS. 5 and 6. In FIG. 7, the X-axis direction (horizontal direction) is a direction (width direction) orthogonal to the arrangement direction (longitudinal direction) of the microlenses of the lens unit 1, and the Z-axis direction (vertical direction) is the direction of the optical axis AXL. It is.

  In FIG. 7, an LED array 300 (see FIG. 3) as an object 30a is arranged on the object plane OP at a position where the center line CL in the width direction of the lens unit 1 is extrapolated. The first microlens 12a is disposed at a position away from the object plane OP by the distance LO. Further, the second microlens 12b faces the first microlens 12a so that the optical axis AXL coincides, and is arranged with a distance LS. The imaging plane IP of the lens unit 1 is a position separated from the second microlens 12b by a distance LI in the optical axis AXL direction. The first microlens 12a has a thickness LT1, and the second microlens 12b has a thickness LT2.

  The first microlens 12a forms an intermediate image 30b as an image of the object 30a located at a distance LO1 in the optical axis AXL direction on an intermediate image plane IMP separated by a distance LI1 in the optical axis AXL direction. The second micro lens 12b forms an image 30c of the intermediate image 30b at the position of the distance LO2 on an image plane IP separated by LI2 in the optical axis AXL direction. At this time, the image 30c is an erecting equal-magnification image of the object 30a.

  The distance LO from the object plane OP of the lens unit 1 to the first microlens 12a is set equal to the distance LO1, and the distance LS between the first microlens 12a and the second microlens 12b is (distance LI1 + distance LO2). The distance LI from the second microlens 12b to the image plane IP of the lens unit 1 is set equal to the distance LI2.

  The first microlens 12a and the second microlens 12b can be lenses having the same configuration. At this time, both the first microlens 12a and the second microlens 12b have a thickness LT1, and a surface having the same shape as the curved surface on the object plane side of the first microlens 12a is the second microlens 12b. The distance LO1 is set to be equal to the distance LI2, and the distance LO is set to be equal to the distance LI. Further, the distance LO2 is set equal to the distance LI1, and the interval LS between the first microlens 12a and the second microphone lens 12b is set to (2 × distance LI1).

The operation of the above configuration will be described.
First, the operation of the printer 100 will be described with reference to FIG.
The surface of the photosensitive drum 41 of the printer 100 is charged by a charging roller 42 to which a voltage is applied by a power supply device (not shown). Subsequently, when the surface of the photosensitive drum 41 charged by the rotation of the photosensitive drum 41 reaches the vicinity of the LED head 3, the surface is exposed by the LED head 3, and an electrostatic latent image is formed on the surface of the photosensitive drum 41. . This electrostatic latent image is developed by the developing device 5, and a toner image is formed on the surface of the photosensitive drum 41.

On the other hand, the paper 101 set in the paper feed cassette 60 is taken out from the paper feed cassette 60 by the paper feed roller 61 and is transported to the vicinity of the transfer roller 80 and the transfer belt 81 by the transport rollers 62 and 63.
When the photosensitive drum 41 rotates and the toner image on the surface of the photosensitive drum 41 obtained by development reaches the vicinity of the transfer roller 80 and the transfer belt 81, a transfer roller to which a voltage is applied by a power supply device (not shown). The toner image on the surface of the photoconductive drum 41 is transferred onto the paper 101 by 80 and the transfer belt 81.

  Subsequently, the paper 101 on which the toner image is formed is conveyed to the fixing device 9 by the rotation of the transfer belt 81, and the toner image on the paper 101 is heated while being pressed by the fixing device 9 to be melted. And fixed on the sheet 101. The sheet 101 on which the toner image is fixed is discharged to the discharge unit 7 by the transport roller 64 and the discharge roller 65, and the operation of the printer 100 is completed.

Next, the operation of the LED head 3 as an exposure apparatus will be described with reference to FIG.
When a control signal for the LED head 3 is transmitted from the control unit of the printer 100 based on the image data, the driver IC 31 causes the LED element 30 to emit light with an arbitrary light amount based on the control signal. The light beam from the LED element 30 enters the lens unit 1, and an image is formed on the photosensitive drum 41.

Next, an outline of the operation of the lens unit 1 will be described with reference to FIG.
An inverted reduced image of the object 30a is formed as an intermediate image 30b on the intermediate image plane IMP by the first microlens 12a. Then, an enlarged inverted image of the intermediate image 30b is formed as the image 30c on the image plane IP by the second microlens 12b. The imaging 30c is an erecting equal-magnification image of the object 30a, and the direction of the arrow (+ X direction) on the object plane OP is the direction of the arrow (+ X direction) on the imaging plane IP. In addition, the first microlens 12a and the second microlens 12b are so-called telecentric in which chief rays from each point on the object plane OP are parallel. Further, among the light rays from the object 30 a, light rays that do not contribute to image formation are blocked by the light shielding plate 21.

  On the other hand, even when the first microlens 12a and the second microlens 12b have the same configuration, an inverted reduced image of the object 30a is formed as the intermediate image 30b on the intermediate image plane IMP, and the second microlens 12a and the second microlens 12b are formed. An enlarged inverted image of the intermediate image 30b is formed as an image 30c on the image plane IP by the lens 12b, and the image 30c is an erecting equal-magnification image of the object 30a, and the direction of the arrow on the object plane OP ( + X direction) is an arrow direction (+ X direction) on the imaging plane IP. In addition, the first microlens 12a and the second microlens 12b are so-called telecentric in which chief rays from each point on the object plane OP are parallel. Further, among the light rays from the object 30 a, light rays that do not contribute to image formation are blocked by the light shielding plate 21.

  The opening 22 (aperture) of the light shielding plate 21 transmits the light beam emitted from the first microlens 12a of the first lens plate 11a and enters the second microlens 12b of the second lens plate 11b. The first microlens 12a of the first lens plate 11a forms an inverted reduced image of the object 30a, and the second microlens 12b of the second lens plate 11b is invertedly enlarged of the inverted reduced image. An image is formed to form an erecting equal-magnification image of the object 30a.

Next, details of the operation of the lens unit 1 will be described with reference to FIGS.
In FIG. 7, a straight line passing through the intermediate image 30b and parallel to the optical axis AXL is AXL ′, an intersection point between the straight line AXL ′ and the object plane OP is 30a ′, and an intersection point between the straight line AXL ′ and the imaging plane IP is 30c ′. .

FIG. 8 is a cross-sectional view of the lens unit 1 and the object plane OP and the imaging plane IP in FIG. 7 by a plane including the straight line AXL ′ and parallel to the arrangement direction of the microlenses.
In FIG. 8, the arrangement direction of the first microlens 12a and the second microlens 12b is the Y-axis direction (horizontal direction in the figure), and the optical axis AXL is the Z-axis direction (vertical direction in the figure). It is arranged to become.

  An inverted reduced image of the object 30a is formed as the intermediate image 30b on the intermediate image plane IMP. In FIG. 8, the light rays of the object 30a appear to be emitted from the point 30a ′. Then, an enlarged inverted image of the intermediate image 30b is formed as the image 30c on the image plane IP by the second microlens 12b. In FIG. 8, the image 30c appears to be formed at a point 30c ′.

  The imaging 30c is an erecting equal-magnification image of the object 30a, and the direction of the arrow on the object plane OP (+ Y axis direction) is the direction of the arrow on the imaging plane IP (+ Y axis direction). In addition, between the first microlens 12a and the second microlens 12b, so-called telecentric, in which principal rays from each point on the object plane OP are parallel to each other. Further, among the light rays from the object 30 a, light rays that do not contribute to image formation are blocked by the light shielding plate 21.

Similarly, when the first microlens 12a and the second microlens 12b have the same configuration, an image 30c of the object 30a is formed, and the image 30c is an erecting equal-magnification image of the object 30a. It has become.
Since the displacement of the position of the lens optical axis coincides with the position where the image is formed, the displacement of the position of the lens optical axis from the straight line CL is the difference between the position of the pixel of the object to be imaged by the lens unit. It is desirable to suppress it to about half of the arrangement interval.

That is, when the resolution of the object is 1200 dpi (1200 pixels are arranged in 1 inch), the pixel arrangement interval is PD≈0.021 mm, and thus the positional deviation from the straight line of the lens optical axis is D3 = It is desirable that (½) × PD = 0.0105 mm or less.
That is, the lenses adjacent to each other in the lateral direction forming the lens plate 11a are continuous in the substantially linear first boundary region 15 extending in the longitudinal direction of the lens plate 11a shown in FIG. The width D1 of the boundary region 15 in the lateral direction of the lens plate 11a is preferably set to a pixel arrangement interval PD = 0.021 mm or less.

  Further, the lenses adjacent to each other in the longitudinal direction forming the lens plate 11a are continuous in a substantially linear second boundary region 16 extending in the short direction of the lens plate 11a shown in FIG. The width D2 of the second boundary region 16 is the arrangement width of the openings 22 of the light shielding plate 21 in the longitudinal direction of the light shielding plate 21 shown in FIG. 6 (the interval between the inner walls of the openings 22 adjacent in the Y-axis direction in FIG. ) Is PY2, the width D2 may be in the range of ((1/2) × PY2) or less.

  Similarly, the width D1 of the first boundary region 15 in the short direction of the lens plate 11a is the array width of the openings 22 of the light shielding plate 21 in the short direction of the light shielding plate 21 shown in FIG. 6 (X in FIG. 6). When the distance between the inner walls of the openings 22 adjacent in the axial direction is TB, the width D1 may be in the range of ((1/2) × TB) or less.

  Here, the first boundary region 15 shown in FIG. 5 extends in the longitudinal direction of the lens plate 11a, and the second boundary region 16 extends in the short direction of the lens plate 11a. The direction in which 15 extends and the direction in which the second boundary region 16 extends are substantially perpendicular. In this way, the first boundary region 15 extends in the longitudinal direction of the lens plate 11a, and the second boundary region 16 extends in the lateral direction of the lens plate 11a, thereby maximizing the effective range of each lens. This makes it possible to increase the amount of light.

In general, if the angle formed by the direction from the lens to the object and the optical axis of the lens is θ, the brightness of the image formed by the lens is proportional to COS ⁴ θ (cosine fourth law).

  Therefore, when an object exists on the optical axis of the lens, the brightness of the image formed by the lens is the brightest. By arranging the lenses in a straight line and facing the linear object (the LED array 300 shown in FIG. 3), the object exists on the optical axes of a plurality of lenses. In a lens array in which lenses in a row are arranged, the image near the optical axis of the lens is bright, the image near the boundary between two adjacent lenses is dark, and the amount of light periodically changes according to the lens array interval. growing.

  Even in a lens array in which one row of lenses is arranged, the smaller the lens arrangement interval, the smaller the change in the amount of light according to the lens arrangement interval. However, by reducing the lens arrangement interval, It is difficult to form the light shielding member, and high accuracy is required when combining the two.

  Therefore, as in the configuration of the present embodiment, by arranging the optical axes of the lens array in which two rows of lenses are arranged in one row, the interval between the optical axes is reduced, so that bright imaging can be formed, and Periodic changes in the amount of light can be suppressed.

  In addition, by forming the boundary between two adjacent lenses in the same row in a straight line, the heights of the two adjacent lens surfaces in the same row are matched, and there is a step in the optical axis direction. Since it does not occur, the lens surface can be formed with high accuracy. Furthermore, it is possible to suppress the generation of stray light that causes light rays to diffusely reflect at the boundary between two adjacent lenses in the same row and reduce the contrast of the image formation.

In addition, a region where light does not enter is formed at the approximate center in the direction orthogonal to the arrangement direction of the apertures (openings) of the light shielding member, and crosstalk light incident from lenses having different optical axes is shielded. Even if the boundary between adjacent lenses is arranged at the approximate center in the direction orthogonal to the lens arrangement direction, the optical characteristics do not change, and the brightness and contrast of image formation do not decrease.
Further, even in the same row, a region where no light beam is incident is formed between two adjacent lenses, and crosstalk light incident from a lens having a different optical axis is shielded, so that the brightness and contrast of imaging are not lowered.

  In this embodiment, in order to increase the light quantity of the lens, the optical axis of the lens forming the lens plate (the first lens plate 11a and the second lens plate 11b shown in FIG. 1) is set to the first boundary region. In the case where a lens unit is configured using a plurality of lens plates, the first boundary region and the second boundary region are shielded by the shielding plate, thereby reducing the light amount. While increasing, it is possible to prevent crosstalk light generated between a plurality of lens plates.

Further, although the first microlens 12a and the second microlens 12b shown in FIGS. 7 and 8 are configured as aspherical surfaces, they may be configured as spherical surfaces.
Furthermore, the first microlens 12a and the second microlens 12b may be formed on a curved surface such as an anamorphic aspherical surface, an XY polynomial, a paraboloid, an ellipsoid, a hyperboloid, or a conic surface.

Furthermore, although the first lens plate and the second lens plate are formed by mold molding, a mold molding method using a resin as a mold may be used, or they may be formed by cutting.
Furthermore, although the material of the first lens plate and the second lens plate uses resin, glass may be used.

Moreover, although the light-shielding plate was produced by the injection molding method using polycarbonate, it is not limited to this, and may be produced by cutting or may be produced by etching a metal.
Furthermore, although the LED array 300 in which a plurality of LED elements 30 shown in FIG. 3 are arranged is used as the light emitting unit, for example, an organic EL may be used as the light emitting unit, or an exposure apparatus using a laser may be used.

  As described above, in the first embodiment, by arranging the optical axis of the lens array in which two rows of lenses are arranged in the first boundary region, a large amount of light from the light source is taken in and bright imaging is performed. The effect that it can form is acquired. Therefore, even if the light quantity of the light source of the exposure apparatus decreases, an effect that an image with sufficient brightness can be formed can be obtained.

In the first embodiment, the lens unit according to the present invention has been described as applied to a printer as an image forming apparatus. In the second embodiment, an example in which the lens unit is applied to a reading apparatus will be described.
The configuration of the second embodiment will be described based on the schematic diagram showing the configuration of the reading apparatus in the second embodiment of FIG. Note that parts similar to those of the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

In FIG. 9, reference numeral 500 denotes a scanner as a reading device that reads an original and generates electronic data as image data.
The scanner 500 includes a reading head 400, a lamp 501, a document table 502, a rail 503, a driving belt 505, a motor 506, and the like.

The reading head 400 takes in a light beam irradiated by a lamp 501 as an illuminating device and reflected by the surface of the document, and converts it into electronic data. The lamp 501 is arranged so that the irradiated light is reflected by the surface of the document and taken into the reading head 400.
The document table 502 is used to place a document 507 on which electronic data is generated, and is formed of a material that transmits visible light.

  The rail 503 is disposed below the document table 502 and allows the reading head 400 to move. The reading head 400 is connected to a driving belt 505 partially stretched by a plurality of pulleys 504, A driving belt 505 driven by a motor 506 is configured to be movable on the rail 503.

Next, the configuration of the read head 400 will be described based on a schematic diagram showing the configuration of the read head of the reading apparatus in the second embodiment of FIG.
In FIG. 10, the read head 400 includes the lens unit 1, a line sensor 401, and a mirror 402.

The mirror 402 bends the optical path of the light beam reflected by the document 507 and causes the light beam to enter the lens unit 1.
The line sensor 401 has a plurality of light receiving elements arranged in a substantially straight line, and converts the image of the original image formed by the lens unit 1 into an electrical signal.

  FIG. 11 shows the configuration of the reading head 400 of this embodiment and the positional relationship between the object plane OP (original 507) and the imaging plane IP. In this embodiment, the lens unit 1 is arranged so that the image plane IP is the line sensor 401 so that the object plane OP is the original 507. The configuration of the lens unit 1 of this embodiment is the same as that of the first embodiment.

The operation of the above configuration will be described.
First, the operation of the reading apparatus will be described with reference to FIG.
When the lamp 501 is turned on and the surface of the original 507 is irradiated, the light beam reflected by the surface of the original 507 is taken into the reading head 400. The driving belt 505 is driven by the motor 506 and the reading head 400 and the lamp 501 move in the left-right direction in FIG. 9, and the reading head 400 takes in the light beam reflected from the entire surface of the document 507.

Next, the operation of the read head 400 will be described with reference to FIG.
The light beam reflected by the original 507 passes through the original table 502, the optical path is bent by the mirror 402, and enters the lens unit 1. The image of the original 507 formed by the lens unit 1 is formed on the line sensor 401, and the line sensor 401 converts the formed image of the original 507 into an electric signal to generate electronic data.

When image data was formed from a document using the reading apparatus according to this embodiment, the same good image data as the document was obtained.
In this embodiment, a scanner is described as an example of a reading device that converts an original image into electronic data. However, sensors and switches that convert optical signals into electric signals, input / output devices using them, and biological It may be an authentication device, a communication device, a dimension measuring device, or the like.

  As described above, according to the second embodiment, it is possible to form an image with sufficient brightness even if the light amount of the illumination device is suppressed in the reading device.

DESCRIPTION OF SYMBOLS 1 Lens unit 3 LED head 5 Developing device 7 Discharge part 9 Fixing device 11a 1st lens plate 11b 2nd lens plate 12a 1st micro lens 12b 2nd micro lens 13a, 13b 1st lens row 14a, 14b Second lens array 15 First boundary region 16 Second boundary region 21 Light shielding plate 22 Opening 30 LED element 31 Driver IC
32 Wire 33 Wiring board 34 Holder 41 Photosensitive drum 42 Charging roller 43 Cleaning blade 51 Toner cartridge 60 Paper feed cassette 61 Paper feed roller 62, 63, 64 Transport roller 65 Discharge roller 80 Transfer roller 81 Transfer belt

Claims (17)

In a lens array in which a plurality of lenses are arranged in two rows,
A plurality of lenses adjacent in the longitudinal direction;
A plurality of lenses adjacent in the short direction,
The lenses adjacent in the lateral direction are continuous in a first boundary region extending in the longitudinal direction,
Each of the lenses has an optical axis in the first boundary region. The lens array according to claim 1, wherein
The lens array, wherein the lenses adjacent in the longitudinal direction are continuous in a second boundary region extending in the lateral direction. The lens array according to claim 1 or 2,
The lens array, wherein a direction in which the first boundary region extends and a direction in which the second boundary region extends are substantially orthogonal. The lens array according to any one of claims 1 to 3,
Each of the lenses has an optical axis at an approximate center in a short direction of the lens array. The lens array according to any one of claims 1 to 4, wherein:
The lens array, wherein the plurality of lenses are arranged in a staggered pattern. The lens array according to any one of claims 1 to 5,
The lens array, wherein each of the lenses is formed so that a radius in the short direction is larger than a radius in the longitudinal direction. The lens array according to any one of claims 1 to 6,
The plurality of lenses are arranged in two rows in the longitudinal direction perpendicular to the optical axis, and the lenses in one lens row have a shape obtained by rotating the lenses in the other lens row by 180 degrees about the rotation axis in the optical axis direction. A lens array characterized by that. A plurality of lenses are arranged in two rows, and have a plurality of lenses adjacent in the longitudinal direction and a plurality of lenses adjacent in the lateral direction, and the lenses adjacent in the lateral direction extend in the longitudinal direction. A lens array continuous in a first boundary region, each lens having an optical axis in the first boundary region;
A lens unit comprising: a light shielding member that shields light from the first boundary region. A lens array according to claim 2;
A lens unit comprising: a light shielding member that shields light from the first boundary region and the second boundary region. A first lens array;
A second lens array;
A light-shielding member disposed between the first lens array and the second lens array and having a diaphragm formed in a longitudinal direction;
The diaphragm is disposed so as to transmit light emitted from the lenses of the first lens array and to enter the lenses of the second lens array;
The lenses of the first lens array form an inverted reduced image of the object, and the lenses of the second lens array form an inverted enlarged image of the inverted reduced image to form an erecting equal-magnification image of the object. ,
8. The lens unit according to claim 1, wherein at least one of the first lens array and the second lens array is the lens array according to claim 1. The lens unit according to claim 10,
The lens unit, wherein a light beam from an object coinciding with an optical axis of a lens of the first lens array is shielded by the light shielding member.   A plurality of lenses are arranged in two rows, and have a plurality of lenses adjacent in the longitudinal direction and a plurality of lenses adjacent in the lateral direction, and the lenses adjacent in the lateral direction extend in the longitudinal direction. An LED head comprising: a lens array which is continuous in a first boundary region and each of the lenses has an optical axis in the first boundary region. A plurality of lenses are arranged in two rows, and have a plurality of lenses adjacent in the longitudinal direction and a plurality of lenses adjacent in the lateral direction, and the lenses adjacent in the lateral direction extend in the longitudinal direction. A lens array continuous in a first boundary region, each lens having an optical axis in the first boundary region;
An LED head comprising: a lens unit having a light shielding member that shields light from the first boundary region. A plurality of lenses are arranged in two rows, and have a plurality of lenses adjacent in the longitudinal direction and a plurality of lenses adjacent in the lateral direction, and the lenses adjacent in the lateral direction extend in the longitudinal direction. A lens array continuous in a first boundary region, each lens having an optical axis in the first boundary region;
An exposure apparatus comprising: a lens unit having a light shielding member that shields the first boundary region. A plurality of lenses are arranged in two rows, and have a plurality of lenses adjacent in the longitudinal direction and a plurality of lenses adjacent in the lateral direction, and the lenses adjacent in the lateral direction extend in the longitudinal direction. A lens array continuous in a first boundary region, each lens having an optical axis in the first boundary region;
An image forming apparatus comprising: a lens unit having a light shielding member that shields the first boundary region.   A plurality of lenses are arranged in two rows, and have a plurality of lenses adjacent in the longitudinal direction and a plurality of lenses adjacent in the lateral direction, and the lenses adjacent in the lateral direction extend in the longitudinal direction. An image forming apparatus comprising: an LED head that is continuous in a first boundary region, and each of the lenses includes a lens array having an optical axis in the first boundary region. A plurality of lenses are arranged in two rows, and have a plurality of lenses adjacent in the longitudinal direction and a plurality of lenses adjacent in the lateral direction, and the lenses adjacent in the lateral direction extend in the longitudinal direction. A lens array continuous in a first boundary region, each lens having an optical axis in the first boundary region;
A reading apparatus comprising: a lens unit having a light shielding member that shields the first boundary region.

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