JP3057396B2 - Image reading unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading unit having good assembling characteristics, and more particularly to an image reading unit using a refractive index distribution type rod lens as an image transmission body, particularly a plastic refractive index distribution type rod lens. is there.

[0002]

2. Description of the Related Art As shown in Japanese Patent Publication No. 47-817, a refractive index distribution type rod-shaped lens made of glass is made by preparing glass fiber having a specific composition and immersing the glass fiber in an ion exchange bath. It is made by a method of giving a refractive index distribution from the center of the cross section to the outer periphery. Differ, the resulting rod-like lens conjugation length of the refractive index distribution type rod-like lenses made by this method for each batch of ion exchange bath
And lens length of's are different, because that is what was different lens length of the lens array made using these lenses, adhesives for incorporating a lens array in which a large number present arrangement the lens to the housing The only way to do this is to use a fixing method or screwing method, and the productivity cannot be increased.

[0003] Aluminum is frequently used as a material of a housing constituting an image reading unit in terms of cost, productivity and moldability, and the molding is performed by a pultrusion molding method. Molding a housing of a complicated shape that can fix the line-shaped light source and CCD sensor resulted in a dimensional error of about ± 0.1 mm between at least both ends, and was made using such a housing. It is difficult for an image reading unit to have good reading characteristics.

[0004]

An image reading sensor in which a lens array, a linear light source, and a CCD line sensor are incorporated in a housing is disclosed in JP-A-3-179315 and JP-A-3-204265. . In assembling these image reading sensors, a lens array, a linear light source, and a CCD line sensor or a photodiode line sensor are connected to the inside of a housing by a method of fixing these members with an adhesive while positioning them. This assembling process can only be performed manually, which hinders automatic assembly of the image reading unit.

[0005]

Where The present inventors have SUMMARY OF THE INVENTION The under consideration in order to develop an image reading unit that can be automatically assembled, for example, JP-A-3-17410
No. 5 and Japanese Patent Application Laid-Open No. 3-213806 disclose a refractive index distribution type rod-shaped lens having a constant conjugate length, and a lens array made of this plastic lens has a fixed lens length. It has been found that the object can be achieved by devising the structure of the housing to be used, and the present invention has been completed.

The gist of the present invention is to provide a lens array, a line light source, an image reading sensor, a CCD array, and a lens array in which a number of refractive index type rod-shaped lenses are juxtaposed and bonded and sandwiched between two substrates. An image reading unit in which a diode array or the like is incorporated in a housing. Preferably, the housing is formed of a split-type housing that can be divided into at least two or more in a longitudinal direction, and a lens array, a linear light source, and image reading sensor, embed into the coupling grooves having a clamping claw portion for fixing these members in the housing Mareteo
Substantially due to the holding claws and the inner wall surface of the coupling groove.
The image reading unit is fixed .

Hereinafter, the present invention will be further described with reference to the drawings.

FIG. 1 is a cross-sectional view of an image reading unit according to the present invention. FIG. 2 shows an image reading unit in which at least two housing members 21 of FIG. It is the figure seen from the side. In the present invention, when fixing the lens array 2, the linear light source 3, and the image reading sensor 4 in the housing 1 as shown in FIG. 1, a coupling groove and a clamping for fixing without using an adhesive or a screwing mechanism. There is a feature in that nails are used. That is, the lens array 2 is fixed to the housing by the lens array coupling grooves 201, 201 'and the holding claws 202, 202', 203, 203 ', and the light source 3 is fixed by the light source coupling groove 204 and the holding claws 205, 205'. The image reading sensor 4 is fixed to the housing by the image reading sensor coupling groove 206 and the holding claws 207 and 207 '.

Reference numeral 5 denotes a refractive index distribution type rod-shaped lens , and 6 denotes two substrates for sandwiching and joining the rod-shaped lens.
It is preferable to use one made of a resin such as S resin, polyamide, or polycarbonate.

[0010] The housing used in carrying out the present invention is:
The structure is complicated because it has a mechanism to fix the lens array, light source and image reading sensor with the groove for connecting each member and the claw for holding without using a complicated method such as adhesive or screwing inside. However, high accuracy is required for this, and therefore, a high potting method using a thermosetting resin such as a phenol resin or an epoxy resin or an injection molding method using a thermoplastic resin such as an ABS resin, polyamide, or polycarbonate is used. It is good to make by the molding method obtained by precision molding. In order to further improve the accuracy of the housing, as shown in FIG. 2, the housing is composed of at least two housing members, and the housing members at both ends of the housing end are as shown in FIG. The shape is preferably, but not limited to, this shape.

According to the present invention, an image reading unit having an arbitrary length can be formed by using such a housing. In the process of assembling the image reading unit using the lens array, bonding by an adhesive, Since it is assembled without using a screwing mechanism and is further assembled without adjusting the position and the like in the assembly process, there is a great advantage that the assembly can be automated.

In order to improve the performance of the image reading unit of the present invention, the difference between the coefficient of thermal expansion of the material forming the substrate of the lens array and the coefficient of thermal expansion of the material forming the housing is made as small as possible. It is desirable that the material is made of aluminum, polyacetal,
Polycarbonate or the like can be used, but an image reading sensor using a plastic housing has a great feature that its performance does not change even when the temperature of its use environment changes.

Hereinafter, the present invention will be described in more detail by way of examples.

[0014]

Example 1 Polymethyl methacrylate ([η] = 0.5
6, measured at 25 ° C. in methyl ethyl ketone (MEK)) 46 parts by weight, benzyl methacrylate 44 parts by weight, methyl methacrylate 10 parts by weight, 1-hydroxycyclohexyl phenyl ketone 0.2 part by weight and hydroquinone 0.1 part by weight
The mixture was heated and kneaded at a temperature of 0 ° C. to obtain a stock solution for forming the first layer (central portion).
In addition, polymethyl methacrylate ([η] = 0.41, MEK
Measured at 25 ° C) 50 parts by weight, 50 parts by weight of methyl methacrylate, 0.2 of 1-hydroxycyclohexyl phenyl ketone 0.2
Parts by weight and 0.1 part by weight of hydroquinone were heated and kneaded at 70 ° C. to prepare a stock solution for forming a second layer, and further, 45 parts by weight of polymethyl methacrylate ([η] = 0.34, measured at 25 ° C. in MEK), 2,2 , 3,3,4,4,5,5-octafluoropentyl methacrylate 35 parts by weight, methyl methacrylate 20 parts by weight, 1-
A mixture prepared by heating and kneading 0.2 parts by weight of hydroxycyclohexylphenyl ketone and 0.1 parts by weight of hydroquinone at 70 ° C. was used as a stock solution for forming a third layer (outer layer). Using a composite spinning machine equipped with a concentric three-layer composite spinning nozzle, three types of stock solutions were sequentially arranged from the center so that the refractive index of the uncured material became lower, and simultaneously extruded strand fibers were obtained.
The viscosity at the time of extrusion was 4.5 × 10 ⁴ poise for the component of the first layer,
The second layer is 2.0 × 10 ⁴ poise, and the undiluted solution of the third layer is 2.2
× 10 ⁴ poise. The temperature of the composite spinning nozzle is
55 ° C.

[0015] Next, each of the layers is passed through a 90 cm-long inter-diffusion processing section, and then 12 fluorescent lamps each having a length of 120 cm and 40 W are passed through the center of the light irradiation sections arranged at equal intervals in a circular shape through a strand fiber. A light transmitting body having a radius (r _o ) of 0.50 mm was taken up by a nip roller at a speed of 50 cm / min. The discharge ratio is the first
Layer: second layer: third layer = 1: 1: 1. Refractive index distribution center (n _o) is 1.512, the peripheral portion is 1.470, the refractive index distribution constant (g) was 0.52.

[0016] cutting the above optical transmission body, polishing the both end surfaces, and the lens of the lens length 7.2 mm, MTF lens was measured using a 4 line pair / mm becomes grating is 57%,
The conjugate length at that time was 15.4 mm. Further, the formed image of the lattice was a clear image with little distortion.

[0017] The large number of sequences of said lens is sandwiched between the bonding adhesive with an adhesive between the substrate formed by two black ABS resin, lens length 7.2 mm, the lens array of length 228 mm, black Injection molding of ABS resin with four cross-sections as shown in FIG. 1 and four housing members having a length of 40 mm for forming a central portion and two housing members having a length of 35 mm for forming both end portions shown in FIG. created in, and a housing in assembled these members, disposed without a lens array <br/> Lee, adjustment of alignment or the like of the LED line light source and the CCD line sensor for a cover glass,
The image reading unit was assembled with the housing end cover attached. Similarly, 100 image reading units were produced, and the MTF was measured using a grid of 4 line pairs / mm.
All values were equivalent to the MTF value in the lens state.

[0018]

EXAMPLE 2 The lens length obtained in Example 1 was 7.2 mm and the length was 228 m.
When an image reading unit was assembled using a lens array, an LED line light source, and a CCD line sensor using a lens array of m. lens array <br/> Lee, line light source of attachment of the CCD line sensor could disposed without any adjustment such as positioning. Further, 100 image reading units to which a cover glass and a housing end cover were attached were manufactured, and the MTF values measured using a grid of 4 line pairs / mm were all equal to the MTF values in the element state.

[0019]

[Brief description of the drawings]

FIG. 1 is a sectional view of an image reading unit according to the present invention.

FIG. 2 is a partial side view of the image reading unit of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Case 2 ... Lens array 3 ... Linear light source 4 ... CCD line sensor 5 ... Refractive index distribution type rod-shaped lens 6 ... Lens array substrates 201, 201 '... Lens array Grooves for coupling 202, 202 ', 203, 203' Claws 204 for clamping the lens array 204 ...... Grooves 205, 205 'for clamping the light source爪Claws 206 for clamping the light source溝 Grooves 207, 207' for coupling the image reading sensorセ ン サ For clamping the image reading sensor Claw 21 ...... Case member 22 ...... Case end cover 23 ...... Cover glass

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takayuki Tanaka 20-1 Miyuki-cho, Otake-shi, Hiroshima Pref. Central Research Laboratory of Mitsubishi Rayon Co., Ltd. (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1 / 028

Claims (2)

(57) [Claims] 1. A is a lens array, an image reading unit which incorporates a line light source and the image reading sensor in a housing formed by joining clamped parallel part between two substrate having a refractive index distribution type rod-like lens, the lens array , a light source, and the image reading sensor is directed embedding Marete into the coupling groove having a clamping claw for each housing unit, out of the clamping claw and the coupling groove
An image reading unit substantially fixed by a wall . 2. The housing according to claim 1, wherein the housing is made of plastic, and the housing is made of a combination of two or more housing members made by injection molding.
The image reading unit according to the above.