JPH0818729A - Image sensor and its production - Google Patents

Abstract

PURPOSE:To uniform the distribution of illuminance on an original surface reading position without inducing a lack in the illuminance of illumination light radiated from plural light emitting elements to the surface of an original. CONSTITUTION:Plural light emitting elements 7 are arranged on the inside of a frame 2, illumination light radiated from these elements 7 is reflected on the surface 5 of an original to be read out and its reflected light is received by a light receiving element 13 through an optical image forming system 10. In this image sensor 1, a lens member 8 capable of executing illuminance uniforming/increasing action for plural illumination light beams radiated from those elements 7 on an original surface reading position 5a is arranged on the way of an optical path from the elements 7 up to the original surface 5. The lens member 8 is constituted of a convex lens member curved at prescribed curvature in both a main scanning direction and a sub-scanning direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor and a method for manufacturing the same, and more particularly to a technique for increasing the illuminance of illumination light emitted from a plurality of light emitting elements toward a document surface or reducing the illuminance deviation. Regarding

[0002]

2. Description of the Related Art As shown in FIG. 7, a general structure of a conventional image sensor is such that a transparent plate 51 such as glass is arranged on one surface of a substantially rectangular frame 50, and reading is backed up by a platen 52 or the like. The original 53 is conveyed while directly contacting the surface of the transparent plate 51.

In the frame 50, the read original 5 is read.
3, a light emitting element 54 that illuminates illumination light, a lens array 55 that condenses the reflected light from the read document 53 to an upright equal magnification, and a light receiving that receives the light condensed by this lens array 55. And an element 56.

A plurality of the light emitting elements 54 are mounted on the light source substrate 57 in a row in a direction orthogonal to the plane of the drawing. Further, on the drive substrate 58 on which the light receiving element 56 is mounted, various electronic components 59 for driving the light receiving element 56 and processing the light reception signal thereof are mounted.

[0005]

By the way, according to the above-mentioned conventional image sensor, the illumination light independently emitted from the plurality of light emitting elements 54 is directly applied to the read original 53. Therefore, the deviation or variation of the illuminance occurs at the document surface reading position 53a.

More specifically, as shown schematically in FIG. 8B, the illumination light L emitted from each light emitting element 54 has a high illuminance at the central portion of each irradiation range r at the document surface reading position 53a. On the other hand, the illuminance at both ends is low.
Due to this, as shown in FIG. 8A, the illuminance distribution curve W1 has a wavy shape with a large amplitude, which causes a large variation in the amount of light applied to the read document 53, which deteriorates the reading performance. It causes trouble.

In order to deal with such a problem, it is considered to set the distance between the light emitting elements 54 and the document surface reading position 53a to be long or to increase the number of the light emitting elements 54 mounted. To be However,
In the former case, the illuminance at the document surface reading position 53a is insufficient, and good reading performance cannot be obtained. In the latter case, sufficient illuminance can be obtained, but the cost rises.

The invention of the present application was conceived under the above circumstances, and the original surface reading position can be achieved without causing the illuminance of illumination light emitted from a plurality of light emitting elements toward the original surface to be insufficient. The problem is to make the illuminance distribution in the field uniform.

[0009]

In order to solve the above problems, the present invention takes the following technical means.

That is, according to the invention described in claim 1 of the present application, a plurality of light emitting elements are provided inside the frame, and the illumination light emitted from these light emitting elements is reflected on the surface of the reading original and then reflected. In an image sensor configured to receive light by a light receiving element via an optical image forming system, a plurality of light emitting elements respectively emitted from the plurality of light emitting elements in the optical path from the plurality of light emitting elements to the reading document surface. The present invention is characterized in that a lens member for performing an illuminance uniforming action and / or an illuminance increasing action of the illumination light at the document surface reading position is provided.

In this case, the lens member can be formed as a convex lens member which is curved with a predetermined curvature in both the main scanning direction and the sub-scanning direction (claim 2).

Then, at a predetermined position of the lens member,
It is preferable that a matte or mask that partially reduces the transmittance is applied (claim 3).

Further, it is preferable that the lens member and the frame are integrally formed.

An optical fiber array plate with which the surface of the read document comes into contact is disposed on one end surface side of the frame, and the optical fiber array portion of this plate can be used as the optical imaging system. 5).

On the other hand, the invention described in claim 6 of the present application is
A method for manufacturing an image sensor according to any one of claims 1 to 5, wherein the illuminance deviation of the illumination light emitted from the plurality of light emitting elements at a document surface reading position is measured, and the measurement is performed. Determining the shape of the lens member based on the illuminance deviation data, and molding the lens member so as to match the shape.

In this case, it is preferable that in the step of molding the lens member, the frame and the lens member are integrally molded by injection molding (claim 7).

[0017]

According to the invention described in claim 1, a lens member performing a predetermined function is provided in the optical path from the plurality of light emitting elements arranged in the frame to the reading document surface. Because of the interposition, the illuminance of the illumination light from each light emitting element to the original surface reading position can be made uniform and / or increased due to the optical characteristics of this lens member.

More specifically, not only the central portion of the irradiation area of each illumination light at the document surface reading position but also the both end portions are provided with the lens function of the lens member such as the light refracting action or the light condensing action. The illuminance increases accordingly. Therefore, not only the variation in the illuminance distribution in the entire irradiation range is reduced as much as possible, but also the illuminance as a whole is increased.

As described above, by disposing the lens member in a place where nothing has existed in the past, the distance between the light emitting element and the reading surface of the original is not lengthened, and the number of light emitting elements is increased. The illuminance can be increased and the illuminance can be made uniform without increasing the value, and the reading performance and quality of the image sensor can be effectively improved.

As an example of the basic shape of the lens member capable of increasing the illuminance and uniformizing the illuminance as described above, as in the invention described in claim 2, the main scanning direction and the sub-scanning direction are formed. An example of the shape is a convex lens shape that is curved with a predetermined curvature in both directions. More specifically, for example, the shape is not a cylinder or a semi-cylindrical shape that is curved with a predetermined curvature in only one direction, but is a shape having, for example, an approximate spherical portion that is curved in both directions. In this case, even if it is a single-convex lens member, the above-mentioned effects can be expected to some extent, but it is more preferable to use a biconvex lens member.

Further, as in the invention described in claim 3, by frosting or masking a predetermined portion of the lens member, for example, an unnecessary portion, as a specific example, the irradiation width of the illumination light is made to have a required dimension. The transmittance will be reduced for the unnecessary portions for setting. This makes it possible to properly adjust the degree of spread of the illumination light that reaches the document surface reading position from the lens member.

Further, as in the invention described in claim 4, when the lens member and the frame are integrally formed,
Its manufacture is greatly facilitated. That is, even though the lens member is separately provided, the number of man-hours required for manufacturing or the number of man-hours for mounting the lens member does not increase, and accordingly, the increase in manufacturing cost can be suppressed.

When the optical fiber array portion of the optical fiber array plate is effectively used as an optical image forming system as in the invention described in claim 5, as in the conventional case, an erecting equal-magnification type or a refractive index distribution is used. Eliminating the need to use mold lens arrays. This eliminates the need for an expensive lens array, and also makes it unnecessary to secure the conjugate length or the image forming distance thereof, which helps to achieve cost reduction and downsizing.

On the other hand, the invention described in claim 6 relates to a method for manufacturing an image sensor having the above-mentioned structure, particularly a method for manufacturing a lens member and its peripheral components. According to this, when molding the lens member, the illuminance deviation of the illumination light emitted from the light emitting element is first measured, and the shape of the lens member is determined based on the measurement result. The shape of the lens member corresponds to the actual illuminance deviation. Therefore, the illuminance distribution is made uniform by the lens member more reliably.

Further, as in the invention described in claim 7, when molding the lens member, it is preferable that the lens member is integrally formed with the frame by injection molding in order to facilitate the molding process and the above-mentioned manufacturing cost. It is more preferable in consideration of the above problem.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below.
A specific description will be given with reference to the drawings.

FIG. 1 is a vertical sectional front view showing the overall structure of an image sensor according to the present invention. As shown in FIG. 1, the image sensor 1 has a schematic structure in which an optical fiber array plate 3 is arranged on the upper surface side of a frame 2 formed integrally, and a read original 5 backed up by a platen 4 or the like is The optical fiber array plate 3
It is configured to be transported while being in contact with the surface of the.

A light source substrate 6 is attached to the lower corner of the frame 2 in an inclined shape.
Light emitting elements 7 such as a plurality of LED elements are mounted on the top in a row. A lens portion 8 forming a part of the frame 2 is interposed in the optical path from the light emitting element 7 to the read document 5. The lens portion 8 performs an illuminance uniformizing action and an illuminance increasing action which will be described later.

As shown in FIG. 2, a plurality of lens portions 8 are formed in a multi-row shape, and each lens portion 8 is formed corresponding to the light emitting side of each of the plurality of light emitting elements 7. ing. The lens unit 8 is arranged in the main scanning direction (a
Both the front and back sides are formed in a biconvex shape with a predetermined curvature with respect to the (-a direction), and the sub-scanning direction (aa)
Similarly, a biconvex shape is also formed in the direction (orthogonal direction) (see FIG. 1). In this embodiment, the radius of curvature in the main scanning direction is set smaller on the back surface side of the lens portion 8 than on the front surface side (see FIG. 5).

When molding the above-mentioned lens portions 8,
The illuminance deviation of the illumination light emitted from each of the light emitting elements 7 at the document surface reading position 5a is measured in advance by using an illuminance measuring means, and the deviation or variation is possible based on the measured illuminance deviation data. The shape of the lens part 8 is determined so as to be reduced. Then, a mold or the like corresponding to the determined shape is manufactured, and the lens part 8 and the frame 2 are molded using the mold or the like.

Frame 2 in which the lens portion 8 is integrated
As the material of the above, translucent acrylic or polycarbonate is suitable, but other resins or the like can also be used. The molding method is also not particularly limited, but the injection molding method is suitable.

On the other hand, as shown in FIGS. 3 and 4, the optical fiber array plate 3 is provided with an optical fiber array portion 10 in which the middle portion in the width direction of the plate portion 9 such as transparent glass is arranged along the longitudinal direction. There is. The optical fiber array unit 10 includes a large number of optical fiber cables 1
A bundle of 0a, and a resin or glass having translucency is filled between the cables 10a. Therefore, as shown by the alternate long and short dash line in FIG. 4, light can be applied to the original surface reading position 5a of the original 5 to be read through the translucent filling portion between the cables 10a.

Two types of transparent electrode patterns 11 and 12 are formed on the back surface of the optical fiber array plate 3 in the vicinity of the optical fiber array portion 10, and the reflected light from the read original 5 is received on the back side thereof. The light receiving element 13 is attached and held. A plurality of the light receiving elements 13 are arranged in a line in a direction orthogonal to the paper surface, and a substrate 14 on which these light receiving elements 13 are mounted is mounted.
Are held on the optical fiber array plate 3 by bonding the bumps 15 and 16 formed on the electrodes to the transparent electrode patterns 11 and 12 by a method such as pressure bonding.

On the back surface side of the optical fiber array portion 10, a protective layer 17 such as a transparent resin covering the light receiving element 13 and the substrate 14 is formed, which protects the light receiving element 13 and the substrate 14. The joint strength with respect to the plate 3 is enhanced. Further, on the back surface side of the optical fiber array portion 10, masks 18 and 19 having a non-light-transmitting property such as black are provided so that a light transmitting portion reaching the light receiving element 13 becomes a strip-shaped region having a predetermined narrow width along the main scanning direction. Are covered by.

As shown in FIG. 1, the frame 2
A drive substrate 20 is attached to the lower end surface of the drive substrate 20. The drive substrate 20 has a bypass capacitor and an operational amplifier for processing a light reception signal transmitted from the light receiving element 13 via the flex cable 21. , Or electronic components 22 such as switches are mounted.

Next, the operation of the above-described embodiment will be described by focusing on the optical characteristics of the lens portion 8 integrally formed on the frame 2.

FIG. 5 schematically shows the optical characteristics of the lens portion 8 corresponding to one light emitting element 7. As shown in the figure, for example, considering the case where light is emitted from three points x, y, z in the main scanning direction of the light emitting element 7, the light from each point is on the back surface of the lens portion 8. Due to the influence of the incident angle and the refractive index of the lens unit 8, when the optical fiber array unit 10, that is, the document surface reading position 5a, is reached, each is focused at a predetermined position.

Assuming that the illuminance of the condensing portion X at the original surface reading position 5a of the light emitted from the point x is 100%, the degree of condensing of the light emitted from the point y is determined. The illuminance at the light portion Y is 90%, and the illuminance at the condensing portion Z of the light emitted from the point z is 80%.
Therefore, the variation in the illuminance of the illumination light emitted from the entire light emitting portion of the light emitting element 7 at the document surface reading position 5a is within the range of 100% to 80%, and the degree of the variation is extremely small. become.

In addition, the position of the light condensing portion Z of the light emitted from the point z is farther from the light condensing portion X as compared with the case where the light goes straight. The irradiation width L1 in the main scanning direction becomes wider than that in the case where no laser beam is interposed. Thereby, the light emitting device 7
Even with a relatively small number of arrangements, the illuminance over the entire area of the document surface reading position 5a can be made sufficient.

If the optical characteristics of each lens unit 8 as described above are schematically depicted, the state as shown in FIG. 6B is obtained. Optimal irradiation by the action of each lens unit 8 as described above. In order to obtain the width L1, it is necessary to set the shape of the front and back surfaces of the lens portion 8 and the magnitude of the refractive index due to the material thereof so as to obtain the characteristics shown in FIG.
In addition, the range of the portion where the light transmittance of the integrated lens portion 8 is matted or lowered by a mask,
That is, it is also necessary to appropriately set the range of the light transmittance lowering portion of the connecting portion of each lens portion 8 and the like.

Then, the light from each light emitting element 7 passes through the lens portion 8 and is subjected to the above-mentioned optical action, so that the light is made uniform with little variation as shown by the solid line in FIG. 6 (a). An illuminance distribution characteristic curve W is obtained. Further, it is clear that the illuminance distribution characteristic curve W has a very small variation in the illuminance distribution as compared with the conventional illuminance distribution characteristic curve W1 shown by the chain line in the figure. In addition to this, the illuminance is increased by the condensing action of the lens unit 8 described above, and as a result, the document surface reading position 5a is obtained.
It is possible to make the illuminance distribution uniform and improve the illuminance.

In the above embodiment, the invention of the present application is applied to the image sensor 1 using the optical fiber array plate 3. In addition to this, for example, an image sensor having a structure as shown in FIG. Also, by providing a lens portion between the transparent plate 51 and the light emitting element 54, the present invention can be similarly applied.

Although the lens portion is formed integrally with the frame, it may be formed as a separate body, and the lens portion itself has separate portions corresponding to the respective light emitting elements. It may be formed independently.

Further, the shape of the lens portion in the above embodiment is a biconvex lens shape in which both the front and back surfaces are curved with a predetermined curvature in both the main scanning direction and the sub scanning direction. Even if only one of them has a single-convex lens shape that is curved in both directions (one surface is a flat surface or a cylindrical surface), if the curvature of the other surface and its refractive index are appropriate, It is also possible to obtain the same effect as.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of an essential part showing an embodiment of an image sensor according to the present invention.

FIG. 2 is a schematic vertical sectional side view taken along the line AA of FIG.

FIG. 3 is a schematic perspective view of a main part showing a configuration near a document surface reading position of the image sensor.

FIG. 4 is a vertical sectional front view of an essential part showing an optical path in the vicinity of the original surface reading position.

FIG. 5 is a schematic side view showing optical characteristics of a lens member that is a constituent element of the image sensor.

FIG. 6 shows the operation of the image sensor,
FIG. 6A is a graph showing a characteristic curve of illumination light, and FIG. 6B is a schematic side view showing an irradiation state of illumination light.

FIG. 7 is a schematic vertical sectional front view showing the configuration of a conventional image sensor.

8A and 8B show the operation of the conventional image sensor, and FIG. 8A is a graph showing a characteristic curve of illumination light.
(b) is a schematic side view showing an irradiation state of illumination light.

[Explanation of symbols]

 1 Image Sensor 2 Frame 3 Optical Fiber Array Plate 5 Reading Document 5a Reading Document Surface Position 7 Light Emitting Element 8 Lens Member (Lens) 10 Optical Image Forming System (Optical Fiber Array) 13 Light Receiving Element

Claims (7)

[Claims] 1. A frame is provided with a plurality of light emitting elements, and illumination light emitted from these light emitting elements is reflected on a reading original surface, and then the reflected light is received via an optical image forming system. In an image sensor configured to receive light by elements, in the middle of the optical path from the plurality of light emitting elements to the reading document surface, the illuminance of the plurality of illumination lights emitted from these light emitting elements at the document surface reading position is uniform. An image sensor, comprising a lens member that performs an activating effect and / or an illuminance increasing effect. 2. The image sensor according to claim 1, wherein the lens member is a convex lens member that is curved with a predetermined curvature in both the main scanning direction and the sub-scanning direction. 3. The image sensor according to claim 1, wherein a predetermined portion of the lens member is provided with a matte or mask that partially reduces the transmittance thereof. 4. The image sensor according to claim 1, wherein the lens member and the frame are integrally formed. 5. An optical fiber array plate which is in contact with the surface of the read document is disposed on one end surface side of the frame, and the optical fiber array portion of the plate serves as the optical imaging system. Claims 1 to 4
The image sensor according to any one of 1. 6. The method for manufacturing an image sensor according to claim 1, wherein the illuminance deviation of illumination light emitted from the plurality of light emitting elements at a document surface reading position is measured. A step of determining a shape of the lens member based on the measured illuminance deviation data and molding the lens member so as to match the shape, and a method for manufacturing an image sensor, comprising: . 7. The method of manufacturing an image sensor according to claim 6, wherein in the step of molding the lens member, the frame and the lens member are integrally molded by injection molding.