JP6411190B2 - Rod lens array, LED print head, image sensor head, image forming apparatus, and image reading apparatus - Google Patents

Description

  The present invention relates to a rod lens array in which a plurality of lenses are arranged, an LED print head, an image sensor head, an image forming apparatus, and an image reading apparatus.

  In a conventional rod lens array, a plurality of gradient index lenses (hereinafter referred to as “lenses”) are arranged in a line, and the lens group is cut to a predetermined length so as to be orthogonal to the light transmission direction. The cut surface is polished to be a mirror surface. Such a rod lens array is widely used as a lens for an LED print head as an exposure device of an LED printer and a lens for a contact image sensor as a reading device (scanner).

  This lens is made of a glass material or a plastic material. A rod lens array in which lenses made of glass material are arranged is a rod lens array in which lenses made of plastic material are arranged using a polishing process generally as a lens cross-section finishing method. In some cases, a linear cutting device that cuts with a cutting blade is used as a lens cross-section finishing method (see, for example, Patent Document 1).

  In order to cut the lens end surface of a rod lens array made of plastic material into a mirror surface using a linear cutting device, all the constituent materials of the rod lens array cut by the linear cutting device are damaged to the cutting blade. The material must not be given. The members constituting the rod lens array made of this plastic material are generally acrylic resin for the lens, silicone adhesive or urethane adhesive for the filling adhesive, and phenol resin, ABS resin, epoxy resin for the side plate material. Alternatively, a plate material such as acrylic resin is used.

JP 2005-18949 A

However, in the conventional technology, when a plate material such as phenol resin, ABS resin, epoxy resin, or acrylic resin is used as the side plate material, the coefficient of thermal expansion is large due to heat, and the expansion due to moisture absorption is large. There is a problem that dimensional deformation occurs with changes in temperature and humidity, and as a result, the positional relationship between the semiconductor array element as the light emitting element and the lens array fluctuates.
An object of the present invention is to solve such problems, and an object of the present invention is to reduce dimensional fluctuations of the rod lens array due to changes in the surrounding environment.

Therefore, the present invention includes a side plate that sandwiches a plurality of plastic lenses arranged in a row, and the side plate includes a first side plate and a second side plate, and the first side plate includes the second side plate. The second side plate is formed of a resin having a smaller linear expansion coefficient than the first side plate, and the first side plate and the second side plate are formed of a resin having a high machinability compared to the side plate of the first side plate. The side plate is arranged continuously in the light transmission direction of the plastic lens, and the first side plate is arranged on the end surface side of the plastic lens .

  According to the present invention as described above, it is possible to reduce the dimensional variation of the rod lens array due to changes in the surrounding environment.

The perspective view which shows the structure of the rod lens array in an Example. Explanatory drawing which shows the adhesion process in an Example Explanatory drawing which shows the cutting process in an Example Explanatory drawing which shows the cutting process in an Example Explanatory drawing which shows the rod lens array in an Example The perspective view which shows the structure of the LED print head in an Example. Sectional drawing which shows the structure of the LED print head in an Example The perspective view which shows the structure of the contact image sensor head in an Example. Sectional drawing which shows the structure of the contact image sensor head in an Example The schematic sectional side view which shows the structure of the LED printer in an Example. Schematic side sectional view showing the configuration of the scanner in the embodiment

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

FIG. 1 is a perspective view showing a configuration of a rod lens array in the embodiment. FIG. 1 (a) is an overall perspective view of the rod lens array, and FIG. 1 (b) is an enlarged view of a main part of the rod lens array.
In FIG. 1, a rod lens array 101 has a side plate that sandwiches a plurality of plastic lenses arranged in a row, and includes a lens array 102, a first side plate 104, a second side plate 105, and a first side plate. It is composed of a side plate 104 and a hybrid side plate 106 to which a second side plate 105 is bonded.

In the lens array 102, refractive index distribution type lenses 102a having a refractive index distribution made of a plastic material are arrayed in a direction orthogonal to the light transmission direction.
The hybrid side plate 106 is obtained by press-bonding a first side plate 104 made of a material with high machinability and a second side plate 105 made of a material having a low linear expansion coefficient via an adhesive. The hybrid side plate 106 includes two first side plates 104, and the second side plate 105 is sandwiched between the two first side plates 104. The first side plate 104 and the second side plate 105 are continuously arranged in the light transmission direction of the lens 102a.

When the length of the first side plate 104 in the light transmission direction of the lens 102 a is t 1 and the length of the second side plate 105 is t 2, the length t 1 of the first side plate 104 is the length of the second side plate 105. The length is shorter than t2.
The lens array 102 is sandwiched from both sides by two hybrid side plates 106 arranged so that the first side plate 104 of the hybrid side plate 106 becomes a cut and cut surface, and is formed by the lens array 102 and the hybrid side plate 106. The lens array 102 and the hybrid side plate 106 are bonded to each other by filling the gap with the adhesive 103.

The cross section of the lens array 102, the cross section of the adhesive 103, and the cross section of the first side plate 104 are mirror-finished by cutting. A receding surface having a predetermined depth H 1 from the cross section of the lens array 102 is in contact with the second side plate 105.
The length Z1 of the rod lens array 101 in the light transmission direction is formed with a predetermined adjustment width in order to obtain an arbitrary conjugate length.
The lens 102a can be formed of an acrylic resin made of, for example, polymethyl methacrylate (PMMA) or methacrylate (MMA).

The first side plate 104 can be formed of, for example, a phenol resin, an epoxy resin, an ABS resin, or an acrylic resin, and is preferably a material with high machinability. The plate thickness t1 of the first side plate 104 can be in the range of 0.5 mm to 2.0 mm, for example.
The second side plate 105 can be formed of an epoxy resin, a phenol resin, an ABS resin, or the like with a glass cloth as a base material in order to suppress the linear thermal expansion coefficient. The value of the linear expansion coefficient is, for example, 15 ppm. / ° C. or less is desirable. The plate thickness t2 of the second side plate 105 can be in the range of 0.5 mm to 2.0 mm, for example. Further, the water absorption rate of the second side plate 105 is desirably 0.1% or less.

Next, a method for manufacturing the rod lens array 101 shown in FIG. 1 will be described with reference to FIGS.
First, as shown in FIG. 2A, a first side plate 104 formed of a material with good workability that suppresses damage to the cutting blade (hereinafter referred to as “a material with high machinability”), and a wire Two plate-like hybrid side plates 106 connected to the second side plate 105 made of a material having a small expansion coefficient are prepared. As shown in FIG. 2B, the lens array 102 is formed by the two hybrid side plates 106. Is inserted to form the rod lens array sheet 107.
At this time, the direction in which the first side plate 104 and the second side plate 105 of the two hybrid side plates 106 extend is arranged in a direction orthogonal to the light transmission direction of the lens array 102.

  Here, although the lens array 102 is shown as a single layer structure, it may be formed to have a plurality of layers. At this time, the lens array 102 is laminated and temporarily fixed using an adhesive previously applied to the hybrid side plate 106, and again between the temporarily fixed lens array 102 and the hybrid side plate 106 sandwiching the lens array 102, By pressing the hybrid side plate 106 in a state where a layer made of an adhesive is formed, the adhesive is filled between the lens array 102 and the hybrid side plate 106 and bonded. In addition, the lens array 102 is sandwiched and pressed between the two hybrid side plates 106 and fixed using a jig, a liquid adhesive is immersed in one end surface, and the adhesive is sucked from the other end surface. The gap formed between the lens array 102 and the hybrid side plate 106 may be filled with an adhesive.

  Next, as shown in FIG. 3A, the rod lens array sheet 107 is cut by using a dicing saw 110 along the center line of the first side plate 104 in the direction in which the first side plate 104 extends, and the rod lens An array 101 is formed. At this time, as shown in FIG. 3B, the length Z2 of the cut rod lens array 101 in the light transmission direction is cut longer than the length Z1 shown in FIG.

After the rod lens array sheet 107 is cut to form the rod lens array 101, as shown in FIG. 4A, a cutting blade 112 fixed to the tip of the cutter wheel 111 is used, as shown in FIG. Thus, by cutting both cross sections of the lens array 102 by the cutting width (length in the light transmission direction) P1, the cross section of the lens array 102 is mirror-finished to form the cross section of the lens array 102.
At this time, by leaving the first side plate 104 by the length P2 in the light transmission direction, the end of the glass cloth base contained in the second side plate 105 is prevented from being exposed, and the cross section of the lens array 102 is reduced. Mirror finish is possible.
In this way, the rod lens array 101 shown in FIG. 5 is completed.

In addition, in the method of manufacturing the hybrid side plate 106 in which the second side plate 105 made of glass cloth as a base material and the first side plate 104 not containing glass cloth are connected in a plane direction, an adhesive or an adhesive is attached to one side. The glass cloth having the predetermined width a (see FIG. 2) is wound up into a roll shape using the base material. The hybrid side plate 106 can be manufactured by a continuous drawing process using the base material thus manufactured. The base material is not limited to glass cloth, and any material can be used as long as the second side plate 105 has a linear expansion coefficient of 15 ppm / ° C. or less.
In this method, the first side plate 104 having excellent machinability is a resin that does not contain a glass cloth base material, and the second side plate 105 having a small linear expansion coefficient is a side plate that contains glass cloth in the base material. Formed.

Next, an LED (Light Emitting Diode) print head having a rod lens array manufactured by the above-described process will be described with reference to FIGS. FIG. 6 is a perspective view showing the configuration of the LED print head in the embodiment, and FIG. 7 is a cross-sectional view taken along line AA of the LED print head in FIG.
The produced rod lens array 101 is bonded to the folder 116 of the LED print head 113 using a UV adhesive. A COB (Chip On Board) 115 in which semiconductor light emitting array elements 114 are die-bonded in a row on a printed wiring board is also bonded to the same folder 116 using a UV adhesive.

The height of the rod lens array 101 relative to the folder 116 is such that when the LED print head 113 is incorporated in a printer as an image forming apparatus, the distance Lo between the upper surface of the rod lens array 101 and the photosensitive drum is the focal point of the rod lens array 101. The rod lens array 101 is bonded to the folder 116 so as to be equal to the distance L0.
The height of the COB 115 relative to the folder 116 is set such that the distance Li from the bottom surface of the rod lens array 101 to the surface of the semiconductor light emitting array element 114 is equal to the focal length L0 of the rod lens array 101. Is adhered to the folder 116.

In order to prevent foreign matter such as toner from entering the folder 116 as necessary, the gap between the rod lens 101 and the folder 116 is sealed with a silicone sealant 117, and the gap between the COB 115 and the folder 116 is filled with silicone. Sealing is performed with a sealing material 118.
An LED printer as an image forming apparatus according to this embodiment will be described with reference to a schematic diagram illustrating a configuration of the LED printer according to the embodiment of FIG.
In FIG. 10, an LED printer 501 includes four process units 502 and 503 that form images of each color of yellow (Y), magenta (M), cyan (C), and black (K) using an electrophotographic method. , 504, 505.

  The process units 502, 503, 504, and 505 are arranged in tandem along the conveyance path 507 of the recording medium 506. Each of the process units 502, 503, 504, and 505 is charged with a photosensitive drum 508 as an image carrier, a charging device 509 that is disposed around the photosensitive drum 508, and charges the surface of the photosensitive drum 508. And an exposure device 510 that selectively irradiates light onto the surface of the photosensitive drum 508 to form an electrostatic latent image. The exposure apparatus 510 includes the LED print head 113 shown in FIGS. 6 and 7 as a light source.

  The LED printer 501 includes a developing device 511 that conveys toner to the surface of the photosensitive drum 508 on which the electrostatic latent image is formed, and a cleaning device 512 that removes toner remaining on the surface of the photosensitive drum 508. Yes. The photosensitive drum 508 is rotated in a direction indicated by an arrow in the drawing by a driving mechanism including a driving source and a gear.

  The LED printer 501 also includes a paper cassette 513 that stores a recording medium 506 such as paper, and a hopping roller 514 for separating and transporting the recording medium 506 one by one. Further, pinch rollers 515 and 516 and the recording medium 506 are sandwiched on the downstream side of the hopping roller 514 in the conveyance direction of the recording medium 506, and the skew of the recording medium 506 is corrected together with the pinch rollers 515 and 516. Registration rollers 517 and 518 are provided for conveyance to 502, 503, 504, and 505, respectively. The hopping roller 514 and the registration rollers 517 and 518 rotate in conjunction with the drive source.

The LED printer 501 has a transfer roller 519 arranged to face the photosensitive drum 508. The transfer roller 519 is made of semiconductive rubber or the like. Further, the transfer roller 519 is set with the potential of the photosensitive drum 508 and the potential of the transfer roller 519 so that the toner image on the photosensitive drum 508 is transferred onto the recording medium 506.
The LED printer 501 also includes discharge rollers 520 and 521 and 522 and 523 for discharging the recording medium 506.

  The recording media 506 loaded on the paper cassette 513 are separated one by one by a hopping roller 514 and conveyed. The recording medium 506 passes through the pinch rollers 515 and 516 and the registration rollers 517 and 518 and passes through the process units 502, 503, 504, and 505 in this order. In each of the process units 502, 503, 504, and 505, the recording medium 506 passes between the photosensitive drum 508 and the transfer roller 519, and the toner images of each color are sequentially transferred from the photosensitive drum 508. The toner image of each color is fixed on the recording medium 506 by being heated and pressurized. The recording medium 506 on which the toner image is fixed is discharged to a stacker 525 by discharge rollers 520 521 and 522 523.

Next, a contact image sensor head having a rod lens array will be described with reference to FIGS. FIG. 8 is a perspective view showing the configuration of the contact image sensor head in the embodiment, and FIG. 9 is a cross-sectional view taken along line AA of the contact image sensor head in FIG.
The produced rod lens array 101 is bonded to the folder 122 of the contact image sensor head 119 as an image sensor head using a UV adhesive. The COB 121 in which the semiconductor light receiving array elements 120 are die-bonded in a row on the printed wiring board is also bonded to the same folder 122 using a UV adhesive.

The height of the rod lens array 101 relative to the folder 122 is such that when the contact image sensor head 119 is incorporated into a scanner as an image reading apparatus, the distance Lo between the upper surface of the rod lens array 101 in the drawing and the document table is that of the rod lens array 101. The rod lens array 101 is bonded to the folder 122 so as to be equal to the focal length L0.
The height of the COB 121 relative to the folder 122 is set such that the distance Li from the bottom surface of the rod lens array 101 to the surface of the semiconductor light emitting array element 114 is equal to the focal length L0 of the rod lens array 101. Is adhered to the folder 122.

In order to prevent foreign matter from entering the folder 122 as required, the gap between the rod lens 101 and the folder 122 is sealed with a silicone sealant, and the gap between the COB 121 and the folder 122 is sealed with a silicone sealant. Seal.
A scanner as an image reading apparatus according to the present embodiment will be described with reference to a schematic diagram illustrating a configuration of the scanner in the embodiment of FIG.
In FIG. 11, reference numeral 600 denotes a scanner as an image reading apparatus that reads an original and generates electronic data as image data.

The scanner 600 includes a contact image sensor head 119, a lamp 601, a document table 602, a rail 603, a driving belt 605, a motor 606, and the like.
The contact image sensor head 119 captures a light beam irradiated by a lamp 601 as an illumination device and reflected by the surface of the document 611 and converts it into electronic data. The lamp 601 is arranged so that the irradiated light is reflected by the surface of the document 611 and taken into the contact image sensor head 119.

The document table 602 is used to place a document 611 on which electronic data is generated, and is formed of a material that transmits visible light.
The rail 603 is disposed below the document table 602 and allows the contact image sensor head 119 to move. The contact image sensor head 119 has a drive belt 605 partially stretched by a plurality of pulleys 504. , And is configured to be movable on the rail 603 by a drive belt 605 driven by a motor 606.

The operation of the above-described configuration will be described with reference to FIGS.
The side plate of the rod lens array 101 is not only the first workable side plate 104 but also the second side plate 105 having a small coefficient of linear expansion due to heat and a low coefficient of expansion due to water absorption. With the configuration of the hybrid side plate 106, the temperature change due to the surrounding environment and self-heating from the COB, or the amount of change in the relative positional relationship between the rod lens array 101 and the semiconductor light emitting array element 114 due to the temperature change, and the rod lens array 101 The amount of variation in the relative positional relationship between the semiconductor light receiving array element 120 and the semiconductor light receiving array element 120 can be suppressed as compared with the rod lens array 101 using the side plate formed only by the first side plate 104.

  Further, in the manufacturing process of the rod lens array 101, the first side plate 104 made of a material with high machinability is cut by the cutting width P1 so that only the length P2 remains, so that the cross-section of the lens array 102 is increased. In the cutting process, wear of the cutting blade 112 due to the cutting blade 112 interfering with the second side plate 105 can be avoided. That is, by arranging a material with high machinability and a material with a small linear expansion coefficient in the light transmission direction (plane direction), it is possible to achieve both suppression of dimensional change and workability. Therefore, the cutting process of the lens surface of the rod lens array 101 can be performed by a cutting process using a linear cutting device.

  Conventionally, in the case of an LED print head in which a semiconductor array element is a light emitting element, a change in the size of the rod lens array results in a change from the output correction data from the rod lens array at the time of shipment. There was a problem that spots or black or white streaks occurred. On the other hand, in the case of a contact image sensor head in which the semiconductor array element is composed of a light receiving element, the size variation of the rod lens array occurs, so that the intensity of incident light that propagates through the rod lens array and enters the light receiving element varies from the corrected state. Therefore, the accuracy of the read image is deteriorated. Therefore, there has been a problem that correction must be frequently performed in order to suppress a decrease in read image accuracy.

Such a problem can be dealt with by replacing the material used for the side plate with a material having a small linear expansion coefficient due to temperature and a material having a small expansion coefficient due to humidity. For example, a material having a small linear expansion coefficient such as FRP woven with glass fibers can be used as the material of the side plate.
However, when such a material is applied to the material of the side plate, the glass material has low machinability, which causes damage to the cutting blade and can be applied to the material of the side plate in the rod lens array made of a plastic lens material. There was a problem that it was not possible.

Therefore, in the present embodiment, a first side plate formed of a material with good workability that suppresses damage to the cutting blade as a side plate of the rod lens array, and a second side plate formed of a material having a small linear expansion coefficient By using a flat hybrid side plate that is connected to each other, the dimensional variation of the rod lens array due to changes in temperature and humidity due to ambient environment and self-heating is suppressed.
Then, by arranging the first side plate having high machinability in the processing position with cutting and cutting in the hybrid side plate, thermal dimensional stability and wetness can be achieved without processing the second side plate inferior in workability. It can be set as the rod lens array which has a side plate excellent in dimensional stability.

  As described above, in this embodiment, the first side plate formed of a material with good workability that suppresses damage to the cutting blade as the side plate of the rod lens array, and the first side plate formed of a material having a small linear expansion coefficient. By using the flat hybrid side plate that is connected to the second side plate, it is possible to suppress the dimensional variation of the rod lens array due to the ambient environment, temperature change due to self-heating, and humidity change.

In addition, in the process of manufacturing the rod lens array, it is possible to greatly reduce the damage of the cutting blade of the linear cutting device used in the lens cutting process, and the effect that the rod lens array can be produced by the linear cutting device is obtained. It is done.
In the present embodiment, the image forming apparatus has been described as an LED printer. However, the image forming apparatus is not limited thereto, and may be a copying machine, a facsimile machine, a multifunction machine, or the like. Further, although the image reading apparatus has been described as a scanner, the present invention is not limited thereto, and may be a copying machine, a facsimile machine, a multifunction machine, or the like.

DESCRIPTION OF SYMBOLS 101 Rod lens array 102 Lens array 104 1st side plate 105 2nd side plate 106 Hybrid side plate 107 Rod lens array sheet 113 LED print head 114 Semiconductor light-emitting array element 115, 121 COB
116, 122 Folder 117, 118 Silicone encapsulant 119 Contact image sensor head 120 Semiconductor light receiving array element 501 LED printer 600 Scanner

Claims (10)

It has side plates that sandwich a plurality of plastic lenses arranged in a row,
The side plate includes a first side plate and a second side plate,
The first side plate is formed of a highly machinable resin as compared to the second side plate,
The second side plate is formed of a resin having a smaller linear expansion coefficient than the first side plate,
The first side plate and the second side plate are continuously disposed in the light transmission direction of the plastic lens, and the first side plate is disposed on an end surface side of the plastic lens. Rod lens array. The rod lens according to claim 1,
The rod lens array, wherein the second side plate has a linear expansion coefficient of 15 ppm / ° C. or less . The rod lens according to claim 1 or 2,
The second side plate is made of a resin containing glass cloth,
The rod lens array , wherein the first side plate is made of a resin not including glass cloth . The rod lens according to claim 3,
The first side plate is formed of any one of a phenol resin, an epoxy resin, an ABS resin, and an acrylic resin . The rod lens according to claim 3 ,
The second side plate is formed of any one of an epoxy resin, a phenol resin, and an ABS resin having a glass cloth as a base material. The rod lens according to any one of claims 1 to 5,
A rod lens array, wherein a cutting surface is formed on the first side plate.   An LED print head comprising the rod lens according to claim 1.   An image forming apparatus comprising the rod lens according to claim 1.   An image sensor head comprising the rod lens according to claim 1.   An image reading apparatus comprising the rod lens according to claim 1.

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