JP2004042426A - Optical writing head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical writing head which is capable of high-speed printing without dot misregistration, vertical streaks and ghost images, is superior in the dimensional stability of a distance between optical axes, has a good aged profile of a joint part environment, can shorten a jointing assembling tact and can cope with tilting dimensional variations in orientations XYZ. <P>SOLUTION: The optical writing head (100) is assembled by direct jointing by positioning a first member (10) where an LED light emitting part (12) is mounted and a second member (20) where a lens mirror part (21) is mounted while a constant distance of optical axes is maintained. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical writing head, and more particularly, to an optical writing head used for an image forming apparatus, a laser beam printer, a plain paper copier, a plain paper FAX, and the like.
[0002]
[Prior art]
Several proposals have conventionally been made as a method of joining and assembling an optical writing head including a light emitting element such as an LED and a lens mirror integrated type equal-magnification imaging element. As one of them, Japanese Patent Application Laid-Open No. H11-263005 (hereinafter referred to as Conventional Example 1) discloses a method in which a first member mounting an LED and a second member mounting a lens mirror are positioned in an intermediate state. There has been proposed a method of indirectly bonding with an ultraviolet curable adhesive via an L-shaped bracket as a joining member. In addition, JP-A-6-195720 (hereinafter referred to as Conventional Example 2) discloses a method of UV bonding a positioned first optical base and a second optical base via a light-transmitting third member. Has been proposed.
[0003]
[Problems to be solved by the invention]
However, according to the above-described conventional example 1, there is a drawback that only horizontal movement in the left / right / front / rear directions can be adjusted. Further, according to Conventional Example 2 described above, the intervening substance is light-transmitting, and is therefore limited to plastic and glass. Further, when the first optical base and the second optical base are made of metal or the like, mismatching of the strength and the coefficient of thermal expansion can be regarded as a disadvantage.
[0004]
The present invention has been made to solve these problems, and provides an optical writing head with excellent dot dimensional stability, capable of high-speed printing without dot displacement, vertical stripes, and ghost images, It is still another object of the present invention to provide an optical writing head which has good junction environment aging characteristics, can shorten the joining assembly tact time, and can cope with dimensional fluctuations in the XYZ directions.
[0005]
[Means for Solving the Problems]
In order to solve the above problem, the optical writing head of the present invention has a constant distance between the optical axes of the first member mounting the LED light emitting unit and the second member mounting the lens mirror unit. Assembled with positioning. And it is characterized in that the first member and the second member are assembled by direct joining. Therefore, it is possible to provide an optical writing head having no dot position deviation.
[0006]
Further, an optical writing head as another invention is characterized in that the first member and the second member are assembled via a third member which is an intermediate member for interconnecting the first member and the second member. Therefore, it is possible to perform an adhesive assembly in which the adhesive structure can be positioned with high precision and the position can be adjusted, and it is possible to provide an optical writing head capable of adjusting the three-dimensional XYZ parallel movement and tilting movement.
[0007]
Furthermore, a mortar-shaped conical through-hole is provided in one of the first member and the second member, and after being aligned with each other, the through-hole is filled with an adhesive or solder and solidified, so that the joining reliability is improved. An optical writing head having a good bonding structure can be provided.
[0008]
The adhesive is preferably an ultraviolet curable resin, an epoxy adhesive, a modified acrylic adhesive, or a tin-lead eutectic solder. Further, an adhesive filled with an inorganic filler and a metal powder is preferable.
[0009]
Further, the conical through-hole provided in one of the first member and the second member, and a shaft-like joining member provided integrally or as a third member in the other member. A fixed gap was provided between the joining member and the position adjustment in each of the X-axis, Y-axis, and Z-axis directions or in all directions of the inclination direction was enabled in the gap. Therefore, an optical writing head having excellent dimensional stability between optical axes can be provided.
[0010]
In addition, after adjusting the position of the through-hole and the joining member, it is filled with an adhesive or solder and assembled by joining, so that the joining structure with high joining reliability enables the adhesive to be supplied to the joining gap by its own weight. An optical writing head having a structure can be provided.
[0011]
Furthermore, by forming the tip shape of the joining member into a trapezoidal shape and a conical convex shape, or by finishing the surface of the through hole and the joining member to a mirror surface, the light is a joining structure capable of supplying the adhesive by its own weight. A write head can be provided.
[0012]
Further, the first member and the second member are formed of aluminum or an aluminum alloy and further subjected to electroless nickel plating, or the first member is formed of aluminum or an aluminum alloy, and soldered to a joint. An optical writing head having excellent dimensional stability between optical axes can be provided by press-fitting a metal having excellent properties or another member plated with good solderability.
[0013]
Further, by positioning and joining the first member and the second member by soldering using a metal having good solderability or a plated joint end having good solderability, the third member is optically connected. An optical writing head having excellent inter-axis dimensional stability can be provided.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
The optical writing head of the present invention assembles the first member and the second member via a third member which is an intermediate member for connecting the first member and the second member.
[0015]
【Example】
FIG. 1 is a sectional view showing the configuration of the optical writing head according to the first embodiment of the present invention. In FIG. 1, the optical writing head 100 of the present embodiment includes a first member 10 and a second member 20. The first member 10 is provided at a predetermined position with a mounting board 11 on which the LED array 12 is mounted. Further, a lens mirror array 21 is provided at a predetermined position on the second member 20. In the optical writing head 100 having such a configuration, the light of the LED array 12 is reflected by the two internal mirrors through the lens mirror array 21 and is focused on the photoreceptor 200 by the other lens to form an image. An optical writing head 100 to be formed. The lens mirror array 21 is manufactured by plastic molding or glass pressing. The LED array 12 and the lens mirror array 21 are aligned and integrally joined and assembled. In the optical writing head 100 having such a structure, the distance (optical axis distance) between the LED array 12 and the lens mirror array 21 and between the lens mirror array 21 and the photoconductor 200 are managed with an accuracy of a micron unit. Is required. The embodiment described below relates to bonding and assembling while maintaining a distance between the LED array and the lens mirror array.
[0016]
FIG. 2 is a sectional view showing the configuration of the optical writing head according to the second embodiment of the present invention. FIG. 3 is a perspective view of the optical writing head of the second embodiment. In both figures, the same reference numerals as those in FIG. 1 indicate the same components. In the optical writing head 100 of the present embodiment, the first member 10 on which the LED array 12 is mounted and the second member 20 on which the lens mirror array 21 is mounted are connected via the third member 30 which is non-transparent. The position is adjusted and joined. As shown in FIG. 3 and FIG. 4 which is a partial cross-sectional view showing the hole portion in detail, a mating joint by a hole 40 provided in the first member 10 and a shaft 41 provided in the second member 20. This is an assembled write head. Using the gap 42 between the hole 40 and the shaft 41, the positions of the X axis, the Y axis, the Z axis, and the inclination are adjusted (the work gripping mechanism is omitted), and the gap 42 is bonded with an adhesive or solder. It is assembled. FIG. 4A shows an example in which a shaft 41, which is a third member that is impermeable to light, is separately prepared. FIG. 4B shows a portion of the shaft 41 of the hole-shaft fitting type, which is a second member. This is an example of manufacturing integrally with the member 20 of FIG.
[0017]
FIG. 5 is a sectional view showing the configuration of the optical writing head according to the third embodiment of the present invention. The optical writing head 100 of the third embodiment shown in the figure is another embodiment of the shaft-hole fitting type joint, in which the hardening of the conical hole 50 and the angled shaft 51 (both are mirror-finished) is performed by ultraviolet curing. This is an example in which the deep curability of the system adhesive 52 is further ensured to improve the bonding reliability. The principle is that the ultraviolet rays irradiated from the upper surface are reflected on the surface 53 of the mirror-shaped conical hole 50 and the surface 54 of the shaft 51 to further promote the photocuring reaction. Also, since the tip of the shaft 51 is trapezoidal or mountain-shaped, if the adhesive is dropped on the apex of the shaft 51, it will be transmitted along the shaft slope by the weight of the adhesive 52 so that the adhesive can be more reliably filled. did.
[0018]
(Specific example 1)
The first member on which the LED array substrate is mounted and the second substrate on which the lens array is mounted are fixed and fixed while maintaining a certain distance between optical axes, and assembled as an optical head. Since it is an A4 or A3 size write head, it is necessary that the LED array and the lens array be finished with a certain straightness. In the position adjustment and the bonding assembly, one of the first member and the second substrate is gripped and the position is adjusted at a target distance between optical axes. In this example, the second member is fixed, the first member is gripped, and the position is adjusted and joined. A mortar-shaped conical hole is provided in the first member, and the hole is filled with an adhesive by dripping and joined to the second member. Since the first member of this example is made of aluminum, it can be easily mirror-finished by cutting. Generally, an ultraviolet curable adhesive has a limit in the thickness of the adhesive layer, and the inside is uncured or the curing reaction is not complete. In this specific example, the curing reaction is further promoted by utilizing the ultraviolet reflection from the bonded adherend. Specifically, the inner surface of the conical hole provided in the first member or the second member is mirror-finished by cutting. When an ultraviolet curable adhesive is dropped into the conical hole and irradiated with ultraviolet light from the upper surface, the curing reaction proceeds to a deep part of the adhesive due to the reflection of the ultraviolet light on the surface of the conical hole. In the case of epoxy-based adhesive (containing metal powder and inorganic filler), modified acrylic-based adhesive, and solder bonding, the curing mechanism is different from UV-curable adhesive, so there is no need to mirror-finish the surface of the conical hole. .
[0019]
(Specific example 2)
In this specific example, the same components as those in the above specific example 1 are used, and this example is an example in which soldering is performed. Although it is possible to directly solder aluminum, in this specific example, aluminum is plated with a metal that can be easily soldered. In this specific example, the first and second members were plated with electroless nickel. Since electroless nickel plating has good solderability, direct solder joining is possible. If a conical hole-shaped metal that can be soldered is press-fitted, and if a metal that can be soldered is press-fitted into the other solder joint, plating of the entire first and second members for soldering is unnecessary. Become. Granular or paste-like solder is supplied to the conical hole, and is joined by heating, melting, and air-cooling as in normal soldering. As a heating source, a heat chip, hot air, light condensing, laser, or the like can be used. In this specific example, granular solder (with flux) was used. Since it is granular, it can be automatically supplied, is easy to implement, and has good workability. In the case of Sn-Pb eutectic solder, the joining operation is performed at a melting point of 183 ° C and an operating temperature of about 230 ° C. In order to respond to recent environmental conditions, lead-free solder is used, but the melting point is about 220 ° C. and the working temperature is about 260 to 270 ° C. According to the solder bonding, since the solder is metal, the fluctuation of the distance between the optical axes in the temperature environment is superior to that of the organic adhesive. A plurality of joints can be instantaneously soldered by using a dedicated device.
[0020]
(Specific example 3)
The method of adjusting the position and joining and assembling the joint end of the shaft and the hole will be described. This is a joining method in which a conical hole and a shaft-like joining end are fitted in a hameai manner, and the gap is filled with an adhesive and solidified. In the first member mounted with an LED array substrate and provided with a mating conical hole, and the second member provided with a mating axial joint end and mounted with a lens array component, the joint end is formed in a hameai manner. This is an example in which a gap is bonded with an adhesive or solder. Further, there is a case where the shaft-shaped joint end is separately provided as a third member (intermediate member) and is joined between the first and second members. In both cases, the first and second members are bonded and assembled while maintaining positional accuracy on the order of microns. Alternatively, there is an example in which a third member is joined to a second member in advance. The third member is not limited to a UV-transparent transparent material, and may be a metal or a plastic. The number and the position of the third members are adjusted according to the external dimensions of the first and second members, heat conduction, required bonding strength, and the like.
[0021]
As described above, the first member and the second member are joined while adjusting the position while maintaining a constant gap. According to this method, bonding can be performed while maintaining a positional relationship in the XYZ directions and at an angle. Further, according to each of the above-described embodiments, since a UV-curable adhesive is used, a mirror-shaped conical hole and a mirror-finished, trapezoidal or mountain-shaped shaft-like joint end are used to form a squeeze eye. When the adhesive is dropped on the center of the mountain-shaped joint end, the adhesive runs along the slope and the gap is filled with adhesive.The adhesive with dimensional change contains inorganic filler etc. and has high viscosity, making it difficult to supply the adhesive. However, since the tip of the shaft is trapezoidal or mountain-shaped, when the adhesive is dropped on the tip of the shaft, the conical hole is automatically filled by its own weight. Since both the hole and the shaft are mirror-finished, deep curing inside the adhesive is ensured by reflection of ultraviolet rays. In the case of an epoxy-based adhesive (containing metal powder and inorganic filler), a modified acrylic-based adhesive, and soldering, mirror finishing is not required. In the case of solder joining, plating for improving solderability, press-fitting of a metal having good solderability, and further, a third member (plating) made of metal having good solderability may be employed.
[0022]
It should be noted that the present invention is not limited to the above embodiment, and it goes without saying that various modifications and substitutions can be made within the scope of the claims.
[0023]
【The invention's effect】
As described above, the optical writing head of the present invention positions the first member on which the LED light emitting unit is mounted and the second member on which the lens mirror unit is mounted while maintaining a constant distance between optical axes. Assembled. And it is characterized in that the first member and the second member are assembled by direct joining. Therefore, it is possible to provide an optical writing head having no dot position deviation.
[0024]
Further, an optical writing head as another invention is characterized in that the first member and the second member are assembled via a third member which is an intermediate member for interconnecting the first member and the second member. Therefore, it is possible to perform an adhesive assembly in which the adhesive structure can be positioned with high precision and the position can be adjusted, and it is possible to provide an optical writing head capable of adjusting the three-dimensional XYZ parallel movement and tilting movement.
[0025]
Furthermore, a mortar-shaped conical through-hole is provided in one of the first member and the second member, and after being aligned with each other, the through-hole is filled with an adhesive or solder and solidified, so that the joining reliability is improved. An optical writing head having a good bonding structure can be provided.
[0026]
The adhesive is preferably an ultraviolet curable resin, an epoxy adhesive, a modified acrylic adhesive, or a tin-lead eutectic solder. Further, an adhesive filled with an inorganic filler and a metal powder is preferable.
[0027]
Further, the conical through-hole provided in one of the first member and the second member, and a shaft-like joining member provided integrally or as a third member in the other member. A fixed gap was provided between the joining member and the position adjustment in each of the X-axis, Y-axis, and Z-axis directions or in all directions of the inclination direction was enabled in the gap. Therefore, an optical writing head having excellent dimensional stability between optical axes can be provided.
[0028]
In addition, after adjusting the position of the through-hole and the joining member, it is filled with an adhesive or solder and assembled by joining, so that the joining structure with high joining reliability enables the adhesive to be supplied to the joining gap by its own weight. An optical writing head having a structure can be provided.
[0029]
Furthermore, by forming the tip shape of the joining member into a trapezoidal shape and a conical convex shape, or by finishing the surface of the through hole and the joining member to a mirror surface, the light is a joining structure capable of supplying the adhesive by its own weight. A write head can be provided.
[0030]
The first member and the second member are formed of aluminum or an aluminum alloy and further subjected to electroless nickel plating, or the first member is formed of aluminum or an aluminum alloy and soldered to a joint. An optical writing head having excellent dimensional stability between optical axes can be provided by press-fitting a metal having excellent properties or another member plated with good solderability.
[0031]
Further, by positioning and joining the first member and the second member by soldering by using a metal having good solderability or a plated joint end having good solderability, the third member is optically connected. An optical writing head having excellent inter-axis dimensional stability can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of an optical writing head according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing a configuration of an optical writing head according to a second embodiment of the present invention.
FIG. 3 is a perspective view of an optical writing head according to a second embodiment.
FIG. 4 is a partial cross-sectional view showing a mating joint according to a second embodiment.
FIG. 5 is a sectional view showing a configuration of an optical writing head according to a third embodiment of the present invention.
[Explanation of symbols]
10; first member, 11; mounting board, 12; LED array,
20; second member, 21; lens mirror array, 30; third member,
40; hole, 41, 51; shaft, 42; gap, 50;
52; UV-curable adhesive, 53, 54; Surface.

Claims (12)

In an optical writing head assembled by positioning a first member on which an LED light emitting unit is mounted and a second member on which a lens mirror unit is mounted while maintaining a constant distance between optical axes,
An optical writing head, wherein the first member and the second member are assembled by direct bonding. In an optical writing head assembled by positioning a first member on which an LED light emitting unit is mounted and a second member on which a lens mirror unit is mounted while maintaining a constant distance between optical axes,
An optical writing head, wherein the first member and the second member are assembled via a third member which is an intermediate member for connecting the first member and the second member. A mortar-shaped conical through-hole is provided in one of the first member and the second member, and after positioning with respect to each other, the through-hole is filled with an adhesive or solder and solidified. 3. The optical writing head according to claim 1. The optical writing head according to claim 3, wherein the adhesive is an ultraviolet curable resin, an epoxy adhesive, a modified acrylic adhesive, or a tin-lead eutectic solder. 5. The optical writing head according to claim 4, wherein the adhesive is filled with an inorganic filler and a metal powder. The conical through-hole provided in one of the first member or the second member, and a shaft-like joining member provided integrally or as the third member in the other member, and 2. A fixed gap is provided between the hole and the joining member, and within the gap, position adjustment in each of the X-axis, Y-axis, and Z-axis directions or in all directions of the tilt direction is enabled. 6. The optical writing head according to any one of items 1 to 5, 7. The optical writing head according to claim 6, wherein after adjusting the position of the through hole and the joining member, the adhesive or the solder is filled and joined and assembled. The optical writing head according to claim 6, wherein the joining member has a trapezoidal shape and a conical convex shape. 9. The optical writing head according to claim 3, wherein the surfaces of the through hole and the joining member are mirror-finished. The optical writing head according to claim 1, wherein the first member and the second member are formed of aluminum or an aluminum alloy, and further subjected to electroless nickel plating. 3. The optical writing head according to claim 1, wherein the first member is formed of aluminum or an aluminum alloy, and a metal having excellent solderability or another plated member having good solderability is press-fitted into the joint. . 3. The first member and the second member are positioned and joined by soldering the third member using a metal having good solderability or an axial joint end plated with good solderability. Or the optical writing head according to 6.

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