JP2011143617A - Print head and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a print head which employs a light emitting element substrate obtained by cutting a connecting piece in an assembled printed wiring board and yet prevents powder generated from the cutting plane from infiltrating into the print head. <P>SOLUTION: The light emitting element substrate 5 in the print head 1 is obtained by fixing light emitting elements 4 on the assembled printed wiring board 41 in which a plurality of printed wiring boards 9 are connected with a plurality of connecting pieces 44 and by cutting off the plurality of connecting pieces 44. Otherwise, it is obtained by cutting off the plurality of connecting pieces 44 in the assembled printed wiring board 41 in which the plurality of printed wiring boards 9 are connected with the plurality of connecting pieces 44 and by fixing the light emitting elements 4. A sealing material 33 is applied to the cutting plane 42 of the plurality of connecting pieces 44 in the light emitting element substrates 5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine and a print head used in the image forming apparatus.

  In an image forming apparatus such as a copying machine, a light emitting element substrate in which a plurality of light emitting elements are arranged substantially linearly on a printed wiring board and a lens array in which a plurality of rod lenses are arranged substantially linearly A print head fixed (arranged) on a cover or the like so that the light emitting point and the lens array face each other is used.

  In such a print head, there is a predetermined space between the light emitting element substrate and the lens array because it is necessary to make the light emitting point of the light emitting element substantially coincide with the focal position of the lens array. Such a space is generally shielded from outside air (external) by a cover and a sealing material for the following reasons (see, for example, Patent Documents 1 and 2).

(Reason 1) When foreign matter such as dust enters the space described above from the outside, the foreign matter adheres to the optical surface of the rod lens, and the light emitted from the light emitting point of the light emitting element is blocked by the foreign matter. Cause image quality degradation.
(Reason 2) When moisture enters the space from the outside, the gold pattern and the semiconductor element are deteriorated, thereby reducing the life of the print head, and thus the life of the image forming apparatus.

  Further, the printed wiring board constituting the light emitting element substrate is easily warped because the longitudinal direction is very long with respect to the short direction. For this reason, for the purpose of fixing (mounting) the light emitting elements with high precision to the printed wiring board, a collective printed wiring board in which a plurality of printed wiring boards are connected by connecting pieces is used (for example, And Patent Document 3).

  When manufacturing the above-described light emitting element substrate using an aggregate printed wiring board, application of an ultraviolet curable adhesive, a thermosetting adhesive, a solder paste, etc. to all the printed wiring boards constituting the aggregate printed wiring board After applying a material and placing a plurality of light emitting elements on the coating material, the coating material is solidified by ultraviolet rays, a reflow furnace, an oven, or the like, and the plurality of light emitting elements are fixed to the collective printed wiring board. That is, when the collective printed wiring board is used, a plurality of light emitting element substrates connected by connecting pieces is manufactured.

  Then, the print element is manufactured by fixing the light emitting element substrate obtained by cutting the connecting piece to the cover using an adhesive or the like, and sealing the gap between the cover and the light emitting element substrate from the outside with a sealing material. it can.

Japanese Patent Laid-Open No. 06-135052 Japanese Patent Laid-Open No. 11-266037 JP 2009-283959 A

  However, when the connecting piece is cut in order to obtain one light emitting element substrate, there is a problem that powder such as glass epoxy constituting the printed wiring board comes out from the cut surface of the light emitting element substrate. This powder penetrates into the inside of the print head (space between the light emitting element substrate and the lens array) due to vibration during conveyance of the image forming apparatus, and adheres to the light emitting point of the light emitting element to form an image. It causes deterioration of the image quality of the device. Note that the print head is very delicate, and even if several micron powder, dust, or the like adheres to the light emitting point of the light emitting element, the image quality of the image forming apparatus is deteriorated.

  The present invention has been made to solve such a problem, and even if the light emitting element substrate is obtained by cutting the connecting pieces of the assembly printed wiring board, the powder generated from the cut surface of the connecting pieces is obtained. An object of the present invention is to provide a print head and an image forming apparatus capable of preventing image quality deterioration of the image forming apparatus caused by the above.

(First invention)
A first invention includes a lens array in which a plurality of rod lenses are arranged and a light emitting element substrate in which a plurality of light emitting elements are fixed to a printed wiring board, and one lens surface of the lens array faces the light emitting element. The present invention relates to a print head in which a lens array and a light emitting element substrate are fixed to a housing.

  The light-emitting element substrate is obtained by fixing the light-emitting elements to a collective printed wiring board in which a plurality of printed wiring boards are connected by a plurality of connecting pieces, and cutting the plurality of connecting pieces, or a plurality of printed wiring boards. Is obtained by cutting a plurality of connecting pieces in a set printed wiring board connected by a plurality of connecting pieces and fixing a light emitting element, and applying a sealing material to the cut surfaces of the plurality of connecting pieces in the light emitting element substrate It is characterized by that.

  With this configuration, the cut surface of the connecting piece in the light emitting element substrate is covered with the sealing material, so that powder of the printed wiring board is not generated from the cut surface. For this reason, after fixing a light emitting element board | substrate to a housing, the powder of a printed wiring board does not penetrate | invade into the inside of a print head from the clearance gap between a housing and a light emitting element board | substrate.

(Second invention)
A second invention is characterized in that, in the print head of the first invention, the sealing material is an adhesive.
With this configuration, the cut surface of the connecting piece is covered with an adhesive, so that the printed circuit board powder is not generated from the cut surface, and the same effect as in the first invention can be obtained. Further, the light emitting element substrate and the housing can be fixed with an adhesive, and when the adhesive is applied to the entire circumference of the light emitting element substrate, the adhesive can also have a function of a sealing material.

(Third invention)
A third invention relates to an image forming apparatus comprising a photoconductor for forming an electrostatic latent image on a surface and the print head according to the first or second invention facing the photoconductor.
With such a configuration, since the print head that exhibits the effects of the first invention or the second invention described above is used, it is possible to provide an image forming apparatus that is free from image quality degradation caused by powder on the printed wiring board generated from the cut surface.

  The present invention can provide a print head or the like in which powder of a printed wiring board does not enter from the gap between the housing and the light emitting element substrate after the light emitting element substrate is fixed to the housing.

Plan view of print head Side view of print head Cross section of print head (cross section AA in FIG. 1) Plan view of an aggregate printed wiring board connected with a printed wiring board Plan view of an aggregate printed wiring board connected with light emitting element substrates A perspective view of one end of an aggregate printed wiring board to which light emitting element substrates are connected Plan view of light-emitting element substrate Perspective view of one end of light emitting element substrate (partial enlarged view of portion W in FIG. 7) A perspective view of a part of the light emitting element substrate (partly enlarged view of V part in FIG. 7) Top view of housing Cross section of housing (cross section BB in FIG. 10) Perspective view of the top surface of one end of the print head during production Perspective view of the bottom surface of one end of the print head during manufacturing Perspective view (partial enlarged view) of a part of the bottom surface of a print head during production Perspective view of the top surface of one end of the print head during production Perspective view of the bottom surface of one end of the print head during manufacturing The figure for demonstrating the structure of an image forming apparatus. Diagram for explaining the positional relationship between the print head and the photoconductor

  Hereinafter, the present invention will be described in detail using examples.

[Print head]
As shown in FIGS. 1 to 3, a print head 1 according to the present invention includes a lens array 3 in which a plurality of rod lenses 6 are arranged and a light emitting element substrate 5 in which a plurality of light emitting elements 4 are fixed to a printed wiring board 9. The lens array 3 and the light emitting element substrate 5 are fixed to the housing 2 so that the light emitting element 4 faces the one lens surface of the lens array 3.

  In other words, as shown in FIGS. 10 and 11, a through hole 30 is formed in the housing 2, and the print head 1 is configured to close the lower portion 32 of the through hole 30 of the housing 2. 5 is fixed to the housing 2, and the lens array 3 is fixed so as to close the upper portion 31 of the through hole 30 of the housing 2.

  As shown in FIGS. 3, 15, and 16, the print head 1 has foreign matter such as dust from the outside in the space inside the print head 1 surrounded by the housing 2, the lens array 3, and the light emitting element substrate 5. The sealing material 33 is applied from the outside of the print head 1 so as not to enter.

  As shown in FIG. 3, when the light emitting point of the light emitting element 4 fixed (mounted) on the surface 10 of the light emitting element substrate 5 is caused to emit light, the print head 1 emits light emitted from the light emitting point as a lens array. 3 is set so that the distance to the image forming point (focus position) that converges (condenses) becomes the conjugate length TC. The conjugate length TC is a distance L from the light emitting point to the lower surface (one lens surface) of the lens array 3, a distance L from the upper surface (the other lens surface) of the lens array 4 to the imaging point, and the lens array 4. And a relationship of TC = T + 2L is established.

(housing)
The housing 2 is made of a resin such as ABS, and as shown in FIGS. 10 and 11, a long through hole 30 is formed at the center, and the upper portion 31 is positioned by inserting a part of the lens array 3. The lens array 3 is slightly larger than the lens array 3. Further, the lower portion 32 of the through hole 30 is slightly larger than the light emitting element substrate 5 so that the light emitting element substrate 5 can be inserted and positioned.

(Light emitting element substrate)
As shown in FIGS. 7 and 8, the light-emitting element substrate 5 is obtained by fixing (mounting) the light-emitting elements 4 on a printed wiring board (bare board) 9 with a conductive adhesive or the like. A plurality of (for example, 256) light emitting points (not shown) are formed in a straight line on the surface of the light emitting element 4, and a plurality of pads 13 are also formed. The plurality of pads 13 and the plurality of pads 14 formed on the surface 10 of the printed wiring board 9 are connected by wires (gold wires) 12.

  In FIG. 8, only one set of pads 13 and 14 and wires 12 is shown for simplicity of explanation, but there are actually a plurality of sets. 7 and 8 show the light-emitting elements 4 fixed in a staggered manner, the light-emitting elements 4 may be fixed in a straight line. As shown in FIG. 3, a bypass capacitor 7 may be mounted on the back surface 11 of the printed wiring board 9, and a metal base or a heat sink (not shown) may be fixed.

  The light emitting element substrate 5 is manufactured as follows. That is, first, as shown in FIG. 4, a collective printed wiring board 41 in which a plurality (five) of printed wiring boards 9 are connected by a plurality of connecting pieces 44 is prepared. The connecting piece 44 is formed by a plurality of long holes 49 penetrating in the thickness direction (Z-axis direction). In other words, the connecting piece 44 is formed between the long hole 49 and the long hole 49.

  Then, a conductive adhesive or the like is applied to all the solid patterns 8 on the five printed wiring boards 9, and all the light emitting elements 4 are placed thereon. For example, when there are 20 light emitting elements 4 fixed to one printed wiring board 9, 100 light emitting elements 4 are placed on the collective printed wiring board 41. Then, a conductive adhesive or the like is cured by heating or the like in an oven or the like, and 100 light emitting elements 4 are fixed to the aggregate printed wiring board 41 (see FIGS. 5 and 6).

  Thereafter, all the connecting pieces 44 in the collective printed wiring board 41 to which the 100 light emitting elements 4 are fixed are cut by a cutting device (not shown). As a result, five light emitting element substrates 5 are obtained. By this method, even if the printed wiring board 9 is long, that is, the length in the longitudinal direction (Y direction) is very long relative to the length in the short direction (X direction), the printed wiring boards 9 are mutually connected to the connecting piece 44. By using the connected collective printed circuit board 41, the warp generated in each printed circuit board 9 can be reduced, and the light emitting element 4 can be fixed to each printed circuit board 9 with high accuracy.

[Print head manufacturing method]
Next, a method for manufacturing the print head 1 according to the present invention will be described.
First, as shown in FIGS. 12 and 13, the lens array 3 is set in the upper portion 31 of the through hole 30 of the housing 2 (see FIGS. 10 and 11), the light emitting element substrate 5 is set in the lower portion 32, and an adhesive 37 is used. And fix. When the lens array 3 and the light emitting element substrate 5 are fixed to the housing 2, fine adjustment using a known technique is performed so that the relationship of TC = 2L + H shown in FIG. I do.

  Next, as shown in FIG. 16, the sealing material 33 is applied at room temperature using a known application device so that the gap 34 between the housing 2 and the light emitting element substrate 5 is not exposed to the outside. At this time, the side surfaces of the light-emitting element substrate 5 have cut surfaces 42 (see FIG. 9) of the plurality of connecting pieces 44, but the sealing material 33 is applied so as to cover all the cut surfaces 42.

  Specifically, as shown in FIG. 14, by providing a notch 36 in the portion of the housing 2 that faces the cut surface 42 of the light emitting element substrate 5, the sealing material 33 is provided on the entire surface of all the cut surfaces 42. It is desirable to make it easy to adhere. And the 1st sealing material 33 is solidified, heating the housing 2 grade | etc., At 4 to 10 degreeC temperature higher than normal temperature. Then, since all the cut surfaces 42 of the light emitting element substrate 5 are covered with the sealing material 33, powder such as glass epoxy constituting the printed wiring board 9 comes out from the cut surface 42, and the powder of the print head 1. There is no intrusion inside.

  In the first embodiment, the sealing material 33 made of silicon resin is applied so as to fill the gap 34 and cover the cut surface 42 in the coating process at a room temperature of 22 ° C., and then in the drying process, The print head 1 was placed in the vicinity of the incandescent lamp for about 15 minutes to solidify the sealing material 33. At this time, the temperature inside the print head 1 is about 30 ° C., and the volume of air inside the print head 1 is expanded.

  Next, when the volume of air inside the print head 1 is in an expanded state (when the inside of the print head 1 is at a temperature 4 ° C. to 10 ° C. higher than room temperature), as shown in FIG. A sealing material 33 made of silicon resin is applied at room temperature (22 ° C.) using a known coating device so as to fill a gap between the housing 2 and the lens array 3, and the sealing material 33 is solidified at room temperature (22 ° C.). I let you. In Example 1, model SE9176 manufactured by Toray Dow Corning was used as the sealing material 33.

  Then, as the temperature of the housing 2 and the like of the print head 1 decreases, the volume of air inside the print head 1 starts to decrease. Further, since the gas is generated when the sealing material 33 made of silicon resin is solidified, a part of the gas enters the inside of the print head 1 and the expansion of the volume of the gas inside the print head 1 starts.

  That is, the volume of the air inside the print head 1 is reduced due to the temperature drop of the print head 1 and the gas inside the print head 1 is caused by the intrusion of the gas of the sealing material 33 into the print head 1. The volume expansion is balanced. For this reason, the sealing material 33 of the print head 1 does not swell toward the outside of the cover 2 and can completely block the inside of the print head 1 from the outside air (outside).

  In addition, as described above, the light emitting element substrate 5 is not only obtained by fixing all (for example, 100) light emitting elements 4 to the collective printed wiring board 41 and then cutting all the connecting pieces 44. Obtained by fixing a plurality of (for example, 20) light emitting elements 4 to each printed wiring board 9 after cutting all the connecting pieces 44 in a state where the light emitting elements 4 are not fixed to the collective printed wiring board 41. It may be the case. In any case, a plurality of cut surfaces 42 are formed on the side surface of the light emitting element substrate 4, and powder such as glass epoxy constituting the printed wiring board 9 comes out from the cut surfaces 42.

Other embodiments are described below.
Note that only differences from the first embodiment will be described for easy understanding.
In the second embodiment, the sealing material 33 in the first embodiment is replaced with an adhesive 37. That is, the reference numeral 33 in FIG. 2, FIG. 3, FIG. 12, FIG. 13, FIG. Even in such a configuration, since all the cut surfaces 42 of the light emitting element substrate 5 are covered with the adhesive, powder such as glass epoxy constituting the printed wiring board 9 comes out from the cut surface 42, and the powder becomes a print head. 1 does not penetrate inside. In this embodiment, since the sealing material is not used, the steps shown in FIGS. 12 and 13 can be omitted.

  A third embodiment according to the present invention will be described with reference to FIGS. FIG. 18 is a partially enlarged view of a part of FIG. 17 in order to make the positional relationship between the print head 1 and the photosensitive drum 25 easy to understand.

(Image forming device)
As shown in FIG. 17, the image forming apparatus according to the present invention is a so-called tandem digital color printer 131, and an image forming process unit 110 that forms an image corresponding to image data of each color, and an image forming process unit 110. And an image processing unit 140 that performs predetermined image processing on the image data received from the personal computer 102 or the image reading apparatus 103. The image forming process unit 110 includes four image forming units 111Y, 111M, 111C, and 111K that are arranged in parallel at a predetermined interval.

  Each of these image forming units 111Y, 111M, 111C, and 111K includes a photosensitive drum 25 as an image carrier (photosensitive member) that forms an electrostatic latent image and carries a toner image, and the photosensitive drum. A charging device 113 that uniformly charges the surface of 25 with a predetermined potential; a print head 1 as an exposure device that exposes the photosensitive drum 25 whose surface is charged by the charging device 113; A developing device 115 for developing the electrostatic latent image and a cleaner (blade) 116 for cleaning the surface of the photosensitive drum 25 after the transfer are provided. Needless to say, the print head 1 is a print head manufactured by the manufacturing method according to the present invention.

  Further, a density detection circuit 117 that detects the toner image density of a test patch (density sample) formed on the photosensitive drum 25 is provided in the vicinity of the downstream side of the developing device 115 so as to face the photosensitive drum 25. It has been. The density detection circuit 117 is connected to the control unit 130 and outputs a toner image density detection value.

  Here, the image forming units 111Y, 111M, 111C, and 111K are configured in substantially the same manner except for the toner stored in the developing device 115. The image forming units 111Y, 111M, 111C, and 111K form yellow (Y), magenta (M), cyan (C), and black (K) toner images, respectively.

  In addition, the image forming process unit 110 includes an intermediate transfer belt 121 onto which the toner images of the respective colors formed on the photosensitive drums 25 of the image forming units 111Y, 111M, 111C, and 111K are transferred, and the image forming units 111Y. , 111M, 111C, and 111K toner images are sequentially transferred (primary transfer) to the intermediate transfer belt 121, and a primary transfer roll 122 as a primary transfer charging device and a superimposed toner image transferred onto the intermediate transfer belt 121 are recorded. A secondary transfer roll 123 as a secondary transfer charging device that performs batch transfer (secondary transfer) onto a paper P that is a material (recording paper), and a fixing device 125 that fixes the secondary transferred image onto the paper P. I have.

  The image forming process unit 110 performs an image forming operation based on a control signal such as a synchronization signal supplied from the control unit 130. At that time, image data input from the personal computer 102 or the image reading device 103 is subjected to image processing by the image processing unit 140 and supplied to each of the image forming units 111Y, 111M, 111C, and 111K via the interface. .

  For example, in the yellow image forming unit 111 </ b> Y, the surface of the photosensitive drum 25 uniformly charged at a predetermined potential by the charging device 113 emits light based on the image data obtained from the image processing unit 140. To form an electrostatic latent image on the photosensitive drum 25.

  This electrostatic latent image is developed by the developing device 115, and a yellow toner image is formed on the photosensitive drum 25. Similarly, magenta, cyan, and black toner images are formed on the respective photosensitive drums 25 of the image forming units 111M, 111C, and 111K.

  The color toner images formed on the respective photosensitive drums 25 of the image forming units 111Y, 111M, 111C, and 111K are sequentially transferred by the primary transfer roll 122 onto the intermediate transfer belt 121 that rotates in the direction of arrow A in FIG. A toner image superimposed on the intermediate transfer belt 121 is formed by electrostatic attraction.

  The superimposed toner image is conveyed to an area (secondary transfer portion) where the secondary transfer roll 123 is disposed as the intermediate transfer belt 121 rotates. When the superimposed toner image is conveyed to the secondary transfer unit, the paper P is supplied to the secondary transfer unit in accordance with the timing at which the toner image is conveyed to the secondary transfer unit.

  Then, the superimposed toner images are collectively electrostatically transferred onto the conveyed paper P by the transfer electric field formed by the secondary transfer roll 123 in the secondary transfer portion. Thereafter, the sheet P on which the superimposed toner image is electrostatically transferred is peeled off from the intermediate transfer belt 121 and conveyed to the fixing device 125 by the conveying belt 124.

  The unfixed toner image on the paper P conveyed to the fixing device 125 is fixed on the paper P by being subjected to fixing processing by heat and pressure by the fixing device 125. Then, the paper P on which the fixed image is formed is conveyed to a paper discharge placement unit (not shown) provided in the discharge unit of the digital color printer 131. That is, since the image forming apparatus according to the eighth embodiment includes the print head 1, it can form a high-quality image.

  The above-described embodiments have been illustrated for the purpose of explanation, and the present invention is not limited thereto. Those skilled in the art will recognize from the claims, the detailed description of the invention, and the drawings. Modifications and additions can be made without departing from the technical idea of the present invention.

  For example, in the above-described embodiment, the five printed wiring boards 9 are connected by the connecting pieces 44 as the collective printed wiring board 41, and the discarded board 45 is connected by the connecting pieces 44 around them. The number of printed wiring boards 9 is not limited to this, and may be 4 or less or 6 or more. Further, the discarded substrate 45 may be omitted.

  In the above-described embodiment, the number of light emitting elements 4 fixed to one printed wiring board 9 is set to 20. However, the number of light emitting elements 4 is not limited to this. It may be 21 or more.

  The present invention is applied to a print head used in a copying machine, a printer, or the like.

DESCRIPTION OF SYMBOLS 1 Print head 2 Housing 3 Lens array 4 Light emitting element 5 Light emitting element board | substrate 6 Rod lens 9 Printed wiring board 41 Collective printed wiring board 42 Cut surface 44 Connection piece

Claims (3)

A lens array in which a plurality of rod lenses are arranged and arranged;
A light emitting element substrate having a plurality of light emitting elements fixed to a printed wiring board,
In the print head in which the lens array and the light emitting element substrate are fixed to a housing so that the light emitting element faces one lens surface of the lens array,
The light emitting element substrate is obtained by fixing the light emitting element to an aggregate printed wiring board in which a plurality of printed wiring boards are connected by a plurality of connecting pieces, and cutting the plurality of connecting pieces, or a plurality of the above The printed wiring board is obtained by fixing the light emitting element by cutting the plurality of connecting pieces in the aggregate printed wiring board connected by a plurality of connecting pieces,
A print head, wherein a sealing material is applied to cut surfaces of the plurality of connecting pieces in the light emitting element substrate.   The print head according to claim 1, wherein the sealing material is an adhesive. A photoreceptor that forms an electrostatic latent image on the surface;
An image forming apparatus comprising the print head according to claim 1 or 2 facing the photoconductor.

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