JPH0530819U - Imaging device - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the mounting accuracy of the board of the image device to the base. [Structure] A base is provided with a convex surface and a concave surface, and the convex surface is exposed to serve as a reference surface, and the back surface of the substrate is brought into contact with the convex surface. The concave surface of the base serves as an escape groove for the adhesive, and the substrate is fixed to the base with the adhesive for the escape groove.

Description

[Detailed description of the device]

[0001]

[Field of use of the device]

 The present invention relates to an image device such as an LED printer head or a contact image sensor, and more particularly to mounting a substrate on which an LED array, a light receiving element array, etc. are mounted on a base.

[0002]

[Prior art]

 An image device in which a light emitting element array such as an LED array or a light receiving element array such as a phototransistor array or a photocell array is mounted on a substrate, and the substrate is fixed to the base is well known (for example, Sekikaihei 1-57,762). (See the official gazette). Since these image devices are optical devices, the mounting accuracy of the light emitting element array and the light receiving element array is important. In such an optical device, it is preferable to form an image on a photosensitive drum or an original through a lens array such as a self-focusing lens array, and the mounting accuracy of the light emitting / receiving element array is preferably ± 50 μm or less. For this purpose, it is necessary that the mounting accuracy of the substrate with respect to the base is about ± 10 μm.

The inventor considered fixing the substrate on which the light emitting / receiving element is mounted to the base with an adhesive or a double-sided tape. An example of such an image device is shown in FIG. In the figure, 2 is a substrate, 4 is an LED array, and 6 is a base, which serves as a housing of the image device. Further, 8 is an adhesive for fixing the substrate 2 to the base 6.

However, it has been found that in such an image device, the mounting accuracy is significantly reduced due to the variation in the thickness of the double-sided tape or the adhesive. For example, assume that the substrate 2 is fixed to the base 6 using the double-sided tape 9 as shown in FIG. Then, the thickness of the double-sided tape 9 is not originally uniform, and since the double-sided tape is soft and easily expands and contracts due to the pressure at the time of fixing, the thickness varies. The figure shows a state in which the double-sided tape 9 is thinned on the right side due to the pressure when fixed, and the substrate 2 is tilted. Such an inclination of the substrate 2 prevents the light from the LED array 4 from being focused on the photoconductor, and distorts the distance between the LED array 4 and a lens array (not shown) to lower the focus accuracy. The thickness of the double-sided tape 9 is practically 50 to 100 μm, specifically about 50 μm in many cases. Therefore, the fixing error of the substrate 2 caused by the variation in the thickness of the double-sided tape 9 cannot be ignored.

The fixing of the substrate 2 to the base 6 with the adhesive 8 is shown in FIG. Practically, the thickness of the adhesive 8 is about 50 to 100 μm, for example, 50 μm, and if pressure unevenness at the time of fixing acts on this, the thickness variation becomes about 30 to 50 μm. Since it is difficult to apply the adhesive 8 to a uniform thickness, and unevenness of the thickness occurs during fixing, the thickness of the adhesive 8 cannot be made constant. Further, if the pressure at the time of fixing is not uniform, the substrate 2 is inclined as shown in FIG. Further, the excess adhesive 8 escapes to the outside of the substrate 2. A particular problem here is the protrusion of the adhesive 8 to the right side of FIG. The area on the right side of FIG. 13 is usually a wiring area formed by a lead frame, a flexible printed circuit board or the like, and if the adhesive 8 sticks out there, it will hinder the wiring. Since such an image device is generally long and has a narrow width, the adhesive 8 tends to protrude laterally.

[0006]

[Challenges for devising]

 An object of the present invention is to prevent the mounting accuracy of the board from being deteriorated by the adhesive when the board is fixed to the base and to prevent the adhesive from protruding.

[0007]

[Device configuration]

 This invention is an image device in which a substrate on which an image element is mounted is fixed to a base with an adhesive, and a concave surface and a convex surface are provided on the base, and the surface of this convex surface is made to be a reference surface, and one of the substrates is The main surface of the base is placed so as to abut the convex surface of the base, and an adhesive is filled between one main surface of the substrate and the concave surface of the base to fix the substrate to the base. And

[0008]

[Function of the device]

 In this invention, the convex surface of the base serves as a reference surface, and the substrate abuts on this portion. The adhesive used does not exist between the convex surface and the substrate or becomes extremely thin. As a result, the mounting accuracy of the board to the base is improved, and the error in the distance between the base and the board and the inclination of the board are eliminated. The adhesive escapes to the concave surface of the base, fills the entire inside of the concave portion, and does not protrude to the outside, thereby increasing the adhesive strength between the base and the substrate.

[0009]

【Example】

 1 and 2 show the first embodiment. In the figure, 2 is a substrate such as glass, and 4 is an LED array as an example of an image element. Instead of the LED array 4, a light receiving element array such as a phototransistor array or a photocell array may be used. Reference numeral 10 is a base, and a metal or a hard synthetic resin such as polyphenylene sulfide or polycarbonate is used. When a synthetic resin such as polycarbonate or polyphenylene sulfide is used as the material of the base 10, conductive particles such as metallic stainless powder are mixed to give conductivity as an earth, and when a photoreceptor not shown is charged. It is preferable to protect the LED array 4 and the like from the noise. Reference numeral 12 is a lens array such as a self-focusing lens array, and 14 is a cover. The base 10 also serves as a housing for the image device and is also used as one side cover. 16 is a board on which the control circuit of the LED array 4 is mounted, and 18 is a clip terminal for connecting the boards 2 and 16. At least both ends of the clip terminal 18 are preferably half-plated with a thickness of about 30 to 40 μm, and a folded-back portion 20 is provided in front of the plated portion. To form a solder pool. As a result, the solder at the positions on the side surfaces of the substrate 2 and the substrate 16 is melted and accumulated in the solder reservoir 20, and then moved to the soldering portion 22 to perform soldering. Reference numeral 24 is a control circuit mounted on the substrate 16, and 26 is an adhesive for fixing the substrate 16. 28 is a common electrode connected to the clip terminal 18, and 30 is a data bus, which is wire-bonded to the individual LED electrodes of the LED array 4.

Reference numerals 32, 34, 36, and 38 are reference surfaces provided on the base 10. The surfaces are made to be the reference surfaces, and the base 10 is projected to form a convex surface. The back surface of the substrate 2 literally comes into contact with the reference surfaces 32, 34, 36, 38 directly without an adhesive, or comes into contact with the reference surface 32 or the like with an extremely thin adhesive. The size and arrangement of the reference plane 32 and the like are arbitrary, but preferably, a reference plane is also provided directly below the LED array 4 (reference plane 34 in the figure), and when the substrate 2 has a left or right warp. , So that the portion directly below the LED array 4 is positioned on the reference surface 34. Although the reference planes 32, 34, 36 and 38 are shown as wide planes in the figure, they may be extremely narrow planes. For example, the surface of the base 10 may be in the shape of a corrugated plate, and the top of this corrugated plate may be the reference surface. The area of the reference surface may be small because the reference surface does not support the load from the substrate 2, but the reference surface only contacts and positions the substrate 2. Reference numerals 40, 42, and 44 are escape grooves for the adhesive, which are concave portions, and the recessed portions as compared with the reference surface 32 are collectively referred to as escape grooves 40, 42, and 44. An adhesive 46 is filled in the escape grooves 40, 42 and 44, and is filled in the entire recess, and is made of, for example, epoxy or acrylic acid. The substrate 2 is fixed to the base with the adhesive 46 of the clearance grooves 40, 42, 44 (when the adhesive 46 is not present on the reference surface 32), or extends very thinly to the adhesive of the clearance groove and the reference surface 32, etc. Both the adhesives (when the adhesive 46 is thinly extended to the reference surface 32 and the like) are fixed to the base 10. The width W and the depth D of the escape grooves 40, 42, 44 are determined so that the adhesive 46 can be accommodated in the escape grooves 40, 42, 44 without protruding to the outside. For example, the width W is 0.5 to 10 mm. More preferably, the depth D is set to about 1 to 3 mm and the depth D is set to about 1 to 3 mm.

3 to 6 show various modified examples. In the modification of FIG. 3, the two escape grooves 50 and 52 are used as the escape grooves, and the three reference surfaces 54, 56 and 58 are used as the reference surfaces. Further, in the modified example of FIG. 4, one relief groove 60 is used as the relief groove, and two reference surfaces 62 and 64 are provided on both sides thereof as reference surfaces. As is clear from these figures, the number of relief grooves and the number of reference planes are arbitrary. In the modification of FIG. 5, the reference surface 66 and the escape grooves 68 are arranged in a grid pattern, and the adhesive accommodating holes 70 are provided to accommodate the excessive adhesive 46. In the modification of FIG. 6, a disc-shaped reference surface 72 is used as the reference surface.

FIG. 7 shows an embodiment in which the LED array 4 is flip-chip connected. In the figure, reference numeral 80 denotes a base, which guides the light from the LED array 4 to the lens array 12 through the glass substrate 2 and the through hole 82. A pair of side blocks 84 are fitted to both ends of the base 70, and the lens array 12 is inserted and held in these side blocks 84. In the figure, 86 and 88 are reference planes, and 90 is an escape groove for the adhesive. Here, the escape groove 90 is provided separately from the through hole 82 because the width of the base 80 is narrow, and if the escape groove 90 is not provided, the resin wraps around the through hole 82 and scatters the light from the LED array 4. Because it will be. Further, in the embodiment, the substrate 2 is fixed to the base 80 mainly by the adhesive 46 of the escape groove 90, and the escape groove 90 is necessary also from this point. In FIG. 7, the back surface of the substrate 2 (the main surface opposite to the LED array 4) is fixed to the base 80. However, in some cases, the vertical relationship between the base 80 and the substrate 2 in FIG. 7 is reversed, a hole for accommodating the LED array 4 is provided in the base 80, and the main surface on the LED array 4 side is used as the base 80. You may fix it. However, since the main surface on the LED array 4 side has the common electrode 28 and the data bus 30 and the surface accuracy is low, it is preferable to fix the back surface to the base.

The assembly process of the embodiment will be described based on the modification of FIG. 3 with reference to FIGS. 8 to 10. For example, as shown in FIG. 8, first, the adhesive 46 is applied or dropped on the entire surface of the contact portion of the base 10 with the substrate 2. Next, as shown in FIG. 9, the substrate 2 is set, and the substrate 2 is pressed against the reference surfaces 54, 56, and 58 as indicated by the arrow in the figure. In this process, the adhesive 46 on the reference surfaces 54, 56, 58 moves to the escape grooves 50, 52, and an extremely thin adhesive remains on the reference surfaces 54, 56, 58. Since the adhesive 46 generally shrinks during the curing process, tensile stress acts on the substrate 2 from the adhesive 46 in the escape grooves 50, 52, and the substrate 2 is fixed so as to abut the reference surfaces 54, 56, 58. The adhesive 46 is accommodated in the escape grooves 50 and 52 and does not stick out to the outside. The state after fixing is shown in FIG.

The adhesive 46 may first be applied or dropped only on the escape grooves 50 and 52. By doing so, the adhesive 46 does not enter the reference surfaces 54, 56, 58, and the substrate 2 can be literally brought into contact with the reference surfaces 54, 56, 58. In this case, what secures the substrate 2 to the base 10 is the adhesive 46 of the escape grooves 50 and 52, and the substrate 2 is pulled toward the base 10 by contraction of the adhesive 46 at the time of curing. It is fixed while being in contact with the reference surfaces 54, 56, and 58 of 10.

Even if the adhesive 46 is applied to the reference surfaces 54, 56, 58 as shown in FIG. 8, if the shrinkage rate and the fluidity of the adhesive 46 are selected, the reference surfaces 54, 56 can be selected. , 58, the adhesive 46 does not remain on the grooves 58, 52, and all the adhesive 46 can be transferred to the escape grooves 50, 52. This is because if the shrinkage rate of the adhesive agent 46 is large and the fluidity at the time of curing is high, the adhesive agent 46 between the reference surfaces 54, 56, 58 and the substrate 2 will all escape to the escape grooves 50, 52 by pressing. This is because they do not remain on the reference planes 54, 56 and 58.

In any case, since the adhesive 46 between the reference surfaces 54, 56, 58 and the substrate 2 is extremely thin or does not exist, no mounting error due to the adhesive 46 occurs. Further, if the width and depth of the escape grooves 50 and 52 are properly selected, the adhesive 46 will not leak to the outside. As a result, the substrate 2 can be fixed without tilting the substrate 2 and in a state of being in close contact with the reference surfaces 54, 56, 58 of the base 10 without further protruding the adhesive 46.

[0017]

[Effect of the device]

 According to this invention, it is possible to fix the substrate to the base without any error in mounting the substrate due to variations in the thickness of the adhesive and without tilting the substrate. Further, excess adhesive can be contained in the escape groove to prevent the adhesive from squeezing out to a place other than the mounting portion, and moreover, the adhesive strength between the base and the base plate can be enhanced. Further, as a result of improving the mounting accuracy of the board, the image quality of the image device is improved.

[Brief description of drawings]

FIG. 1 is a side view of an image device according to an embodiment.

FIG. 2 is an enlarged side view of essential parts of the embodiment shown in FIG.

FIG. 3 is an enlarged side view of essential parts of another embodiment.

FIG. 4 is an enlarged side view of a main part of still another embodiment.

FIG. 5 is an enlarged perspective view of a main part of still another embodiment.

FIG. 6 is an enlarged perspective view of a main part of still another embodiment.

FIG. 7 is a sectional view of still another embodiment.

FIG. 8 is an enlarged side view of an essential part showing a state at the time of applying an adhesive in the embodiment of FIG.

9 is an enlarged side view of an essential part showing a state when setting a substrate in the embodiment of FIG.

FIG. 10 is an enlarged side view of an essential part showing a state after substrate suction in the embodiment of FIG.

FIG. 11 is a perspective view of a main part of a conventional image device.

FIG. 12 is an enlarged side view of a main part of a conventional image device.

FIG. 13 is an enlarged side view of a main part of another conventional image device.

[Explanation of symbols]

 2 substrate 4 LED array 10 base 12 lens array 14 cover 32, 34, 36, 38 reference surface 40, 42, 44 adhesive escape groove 46 adhesive 54, 56, 58 reference surface 50, 52 escape groove 80 base 84 side block

Claims (1)

[Scope of utility model registration request] 1. In an image device in which a substrate on which an image element is mounted is fixed to a base with an adhesive, a concave surface and a convex surface are provided on the base, and the surface of the convex surface is exposed to serve as a reference surface. It is placed such that one main surface is in contact with the convex surface of the base, and an adhesive is filled between one main surface of the substrate and the concave surface of the base to fix the substrate to the base. The imaging device.