JPH05134104A - Light converging microlens array structure body - Google Patents

Abstract

PURPOSE:To make a housing unnecessary, also precise positioning unnecessary, simplify the installation structure and installation adjustment work, and correct the warp. CONSTITUTION:A microlens array structure body is composed of a strip like lens array 30 consisting of a large number of refractive index profile rod lens 38 and a strip like transparent photoconductive material 32 stuck to the end face of the lens. For the transparent photoconductive material, its size in the optical axial direction is set to be the optical length equivalent to the lens working distance of the lens array and both sides 32a in the longitudinal direction (and both sides 32b) are surface-roughened. The structure having a black, light absorptive layer on the roughened surface is preferable. There may be a structure wherein the transparent photoconductive material is joined to and united with a light-emitting (light-receiving) element array.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light converging microlens array structure in which a large number of gradient index rod lenses are aligned, and more specifically, a transparent light guide member having a roughened side surface is used as a lens. The present invention relates to a light converging microlens array structure integrally bonded to the lens end surface of an array. The light converging microlens array structure is useful as an optical system such as an image reading unit of a facsimile or an optical print head of a printer.

[0002]

2. Description of the Related Art A strip-shaped light converging microlens array in which a large number of minute gradient index rod lenses are arranged in an array between two side plates has been conventionally known. This lens array is characterized in that it can form a single continuous erecting equal-magnification real image as a whole, has a short optical path length, and does not require a reversing mirror. Therefore, it is an optimal lens for optical systems such as facsimiles and printers, and is put to practical use.

FIG. 6 shows an example of application to a contact image reading unit of a facsimile. This is lens array 1
0 is held in a housing 12 having a special structure, the image sensor array 14 is attached to one opening end of the housing 12, the other opening end is covered with a cover glass 16, and the space inside the cover glass 16 is illuminated. The light source (light emitting diode) 18 is provided. FIG. 7 shows an example of application to an optical print head of a printer. This is a structure in which the lens array 10 is held in a housing 22, a light emitting diode array 24 is attached to one open end of the housing 12, and the lens array 10 is bonded with a silicone sealant 26.

When using such a lens array, it is necessary to arrange the three surfaces of the object plane, the lens array and the image plane in an accurate positional relationship. In particular, it is important to install the lens array at the center of the object plane and the image plane. Therefore, in the related art, as described above, a housing having a special structure is used, and the lens array is accurately positioned and attached to the housing.

[0005]

As described above, in the prior art, some kind of housing is required to mount the lens array, and therefore there is a limit in terms of size reduction and weight reduction. Further, when the lens array is attached to the housing, it is necessary to obtain optimum optical performance, special processing such as notches and holes are required at both ends of the lens array for positioning, and fine adjustment work is also required. Further, since the notches and holes for positioning are machined after polishing and finishing, there is a possibility that the lens surface may be soiled or scratched, resulting in poor workability.

As various devices incorporating a light-focusing microlens array are being miniaturized, it is required to make the shape of the lens array smaller and smaller, and recently, the height (corresponding to the rod lens length) 4 to A very elongated shape having a width of 5 mm, a width of 3 to 4 mm and a length of about 280 mm is also commercially available. In particular, in such an elongated shape, the longitudinal warp and the lateral warp increase. In order to correct these warps, it is necessary to separately support them at places other than both ends, which complicates the mounting structure and requires complicated warp correction work.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art, to eliminate the need for a housing having a special structure when incorporating it in equipment, to eliminate the need for precise positioning, and to simplify the mounting structure and mounting adjustment work. The present invention is to provide a light-focusing microlens array structure which can be made into a desired shape and whose warp is corrected.

[0008]

According to the present invention, a strip-shaped lens array in which a large number of microscopic gradient index rod lenses are arranged and a strip-shaped lens array attached to at least one lens end surface of the lens array are provided. It is a light converging microlens array structure including a transparent light guide member. Here, the size of the transparent light guide member in the lens optical axis direction is set to an optical length corresponding to a lens working distance of the lens array,
In addition, at least both side surfaces in the longitudinal direction are roughened. In particular, it is preferable that the strip-shaped transparent light-guiding member is roughened on both side surfaces and both end surfaces in the longitudinal direction and subjected to a flare cut treatment for covering them with a black light absorbing layer.

Further, the present invention is a light converging microlens array structure in which a light emitting element array and / or a light receiving element array is joined and integrated with the transparent light guide member, which are image reading units for facsimiles and printers. It is a suitable component when configuring the optical system of the optical print head.

[0010]

The strip-shaped transparent light guide member attached to at least one lens end surface of the lens array eliminates the need for precise positioning between the object plane and the image plane due to strict control of the dimension of the lens in the optical axis direction. To do. Further, the lens array, which is easily warped in terms of shape and material, is bonded and integrated so as to follow the transparent light guide member which is hard to be warped, so that the mechanical strength of the light converging microlens array structure is improved, and thereby the lens is formed. The warp of the array is corrected naturally. The flare cutting process performed on both side surfaces (and both end surfaces) of the transparent light guide member in the longitudinal direction removes stray light and improves contrast.
Further, by covering the lens end surface of the lens array with the transparent light guide member, fogging of the lenses is prevented and reliability is improved for a long period of time.

[0011]

1 is a perspective view showing an embodiment of a light converging microlens array structure according to the present invention. This light converging microlens array structure is a structure in which a transparent light guide member 32 is bonded and integrated to at least one lens end surface (only one in this embodiment) of a strip-shaped lens array 30. The structure of the lens array 30 itself may be the same as the conventional product.

The lens array 30 includes spacers 34 at both ends.
In this structure, a large number of minute gradient index rod lenses 38 are regularly and precisely arranged between two side plates 36 facing each other with a black resin 40 filled in the lens gaps. The black resin 40 is for removing stray light, and is made of a flexible material so as not to give stress to the rod lens 38. In order to reduce the thermal strain and increase the strength with respect to the rod lens 38, a glass cloth base epoxy resin laminated plate (FRP) having the same characteristics as the thermal expansion of the rod lens 38 is used for the side plate 36.

The transparent light guide member 32 is in the form of a strip having the same length and width as the lens array 30, and is set so that its dimension in the lens optical axis direction is an optical length corresponding to the lens working distance of the lens array 30. To do. At least both side surfaces 32a in the longitudinal direction thereof are roughened, and are attached to at least one lens end surface of the lens array 30 as described above. This is a feature of the present invention. In the embodiment shown in FIG. 1, both end faces 32b in the longitudinal direction of the transparent light guide member 32 are also roughened. Note that the roughened surface is shown with fine dots for easy understanding of the drawing.

The transparent light guide member 32 is used for the lens array 3 as shown in FIG. 1 or FIG.
In some cases, it may be adhered to one of the lens end faces of No. 0.
In some cases, it may be adhered to both lens end faces of the lens array 30 as shown in FIG. In particular, when the transparent light guide members 32 are attached to both of them, the rod lens portion is completely sealed and is not exposed to the air, so that no fog is generated and there is an advantage that long-term reliability can be secured.

The roughening of the transparent light guide member 32 can be easily carried out, for example, by chemically processing the surface into a grain shape (chemical etching). By this roughening, stray light is diffusely reflected to eliminate specular reflection of internal light, and the contrast is improved with only effective light. Although only such roughening is effective, as shown in the enlarged view, the black light absorbing layer 4 is further added.
The coating of 2 is extremely preferable because it can absorb stray light that is diffusely reflected to further improve the contrast and has the effect of preventing the intrusion of light from the outside. The transparent light guide member 32 is made of glass or a plastic material, and for example, flare cut treatment (roughening and roughening is performed on the entire surface of a glass plate having a thickness matching the width of the required transparent light guide member and a width matching the length. A black light absorbing layer coating) is performed, and the product is easily mass-produced by cutting it out with an optical length corresponding to the lens working distance of the lens array.

This light converging microlens array structure is strictly controlled so that the dimension of the transparent light guide member 32 in the lens optical axis direction has an optical length corresponding to the lens working distance of the lens array. The transparent light guide member 32 can be easily incorporated in various devices with the surface (the surface facing the bonding surface with the lens array 30) as a reference.

FIG. 3 shows another embodiment of the present invention.
In this structure, a transparent light guide member 32 is bonded to one lens end surface of the lens array 30, and a light emitting diode array 44 is further bonded to the other surface of the transparent light guide member 32, so that the whole light converging microscopic structure is integrated. It is a combined lens array. A light receiving element (image sensor) array may be bonded instead of the light emitting diode array. As a result, it can be more easily incorporated into a device or the like. Stray light a is diffusely reflected or absorbed by the flare cutting process of the transparent light guide member 32 to eliminate specular reflection of internal light, and effective light b
Only as a result, an image with good contrast can be obtained.

FIG. 4 shows the correction of the warp of the lens array 30. An L-shaped assembly jig 46 is used to bond the lens array 30 and the transparent light guide member 32. For example, an ultraviolet curable resin is used as the adhesive, and the adhesive is used for the lens array 30.
And the transparent light-guiding member 32, and is pressed against the corner portion of the L-shaped assembly jig 46, pressed from above, and irradiated with ultraviolet rays to be cured. The groove 48 provided on the side surface of the L-shaped assembly jig 46 is a relief area for the adhesive to overflow. As a result, the lens array 30 that is easily warped is adhered and integrated so as to follow the transparent light guide member 32 that is hard to warp, the mechanical strength of the light converging microlens array structure is improved, and the warp of the lens array 30 naturally occurs. Will be fixed.

FIG. 5 is a partially exploded perspective view of another example of the light converging microlens array structure according to the present invention. Normally, the surface (lower surface) of the lens array facing the transparent light guide member and both surfaces (upper and lower surfaces) of the transparent light guide member perpendicular to the lens optical axis are polished. However, in order to omit the complicated polishing step, here, each of the above surfaces is used as a precision cut surface, and the transparent light guide member 32 having the same refractive index as the lens array 30 is adhered with an ultraviolet curable resin having the same refractive index. To adopt. Further, the transparent light guide member 32 and the light emitting diode array 44 are also adhered with an ultraviolet curable resin having the same refractive index. In the light-focusing microlens array thus obtained, the refractive index is the same even without polishing so that reflection does not occur, the optical performance is not deteriorated, the number of steps is reduced, and the manufacturing cost is reduced. Reduction can be achieved.

[0020]

As described above, according to the present invention, since the lens array and the transparent light guide member are integrally bonded, the lens array which is easily warped is bonded and integrated so as to follow the transparent light guide member which is hard to be warped. The mechanical strength of the light converging microlens array structure is improved, so that the warp of the lens array is naturally corrected. In addition, since the strip-shaped transparent light guide member attached to at least one lens end surface of the lens array strictly manages the lens optical axis direction dimension, precise positioning between the object plane and the image plane and Fine adjustment is not required, and it is easy to incorporate in equipment. Furthermore, since flare cut processing is applied to both side surfaces (and both end surfaces) in the longitudinal direction of the transparent light guide member, stray light is removed and contrast is improved.

If the light-emitting (light-receiving) element array is integrally bonded as the light-focusing microlens array structure of the present invention, it can be more easily attached to a device. In addition, the transparent light guide member covers the lens end surface of the lens array, thereby preventing fogging of the lenses and improving long-term reliability.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a light-focusing microlens array structure of the present invention.

FIG. 2 is an end view of a light converging microlens array structure of the present invention.

FIG. 3 is an end view showing another embodiment of the present invention.

FIG. 4 is an explanatory view showing an assembled state of the light converging microlens array structure of the present invention.

FIG. 5 is a partial exploded perspective view showing still another embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an example of a conventional technique.

FIG. 7 is an explanatory diagram showing another example of the conventional technique.

[Explanation of symbols]

 30 lens array 32 transparent light guide member 32a side surface 32b end face 34 spacer 36 side plate 38 rod lens 42 black light absorbing layer 44 light emitting diode array 46 L-type assembly jig

Claims (3)

[Claims] 1. A strip-shaped lens array in which a large number of minute gradient index rod lenses are arranged in an array, and a strip-shaped transparent light guide member attached to at least one lens end surface of the lens array, The transparent light guide member has a dimension in the lens optical axis direction set to an optical length corresponding to a lens working distance of the lens array, and at least both longitudinal side surfaces thereof are roughened. A light converging microlens array structure. 2. The strip-shaped transparent light guide member is roughened on four sides, that is, both side faces and both end faces in the longitudinal direction, and is covered with a black light absorbing layer. The light-focusing microlens array structure described. 3. The light converging microlens array structure according to claim 1 or 2, wherein a light emitting element array or a light receiving element array is joined and integrated with a transparent light guide member.