JPH08321914A - Image senser - Google Patents

Abstract

PURPOSE: To obtain a high photoelectric conversion efficiency with high S/N by using an external disturbance light limit member provided at the surrounding of an incident end so as to shut an external disturbance light thereby preventing crosstalk. CONSTITUTION: A cover plate 6 is stuck to one side 3c (optical guide path forming face) of a waveguide board 3 while its cover end face 6a is in press contact with an external disturbance light limit member 10. Thus, a capillary 8 of a waveguide board 3 is closed by the cover plate 6 thereby allowing a waveguide core 9 in an optical waveguide 7 to be surrounded by the waveguide board 3 whose refractive index is lower than that of the waveguide core 9 and by the cover plate 6. Metallic reflecting films 11, 12, 13 are provided to an apex face 10b of the external disturbance light limit member 10, an incident end face 3a of the waveguide board 3, and a side face 6a of the cover plate 6 to prevent it that crosstalk takes place due to incidence of a scattered light from an adjacent lens section 2a to an incident end 7a. Thus, a high photoelectric conversion efficiency with high S/N is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor used for a one-dimensional reading optical system of a hard copy image, and more particularly to a reduction image sensor using an optical waveguide.

[0002]

2. Description of the Related Art In recent years, as the demand for image reading by facsimiles, image scanners, digital copying machines, etc. has increased, there has been a demand for higher performance and miniaturization of one-dimensional image sensors for converting image information into electric signals.

Conventionally, in a one-dimensional image sensor, a reduction type sensor having a sensor length shorter than a document width and reading an image using a reduction optical system, and an optical system having a reduction ratio of 1: 1 are connected at a magnification of 1: 1. There is a contact type sensor (also referred to as a unity size type sensor) for reading an image.

FIG. 15 is a conceptual diagram of a reduction type image sensor. In the figure, the document surface G is illuminated by a linear light source 60 such as a linearly arranged light emitting diode (hereinafter referred to as “LED”) array or a fluorescent lamp, and reflected light from the document surface G is CCD by a lens 61. The photoelectric conversion element array 62 such as
Converts the image information of the document surface G into an electric signal in time series and outputs it.

The resolution of this reduction type image sensor is determined by the pixel pitch of the photoelectric conversion element array 62 and the lens performance. The reading resolution is 200 dpi (200 dots per inch) and the reading width is 256 mm.
Under the condition, the distance (optical path length) d1 from the document surface G to the photoelectric conversion element array 62 is about 330 mm.

The reduction type image sensor having such a structure is low in price and can read at high speed.

On the other hand, in the contact-type image sensor shown in FIG. 16, the detectors such as the photoelectric conversion element array 63 are provided on the original surface G.
Of the photoelectric conversion element array 6 that is arranged so as to cover the entire reading width, that is, the reflected light from the document surface G illuminated by the light source 64 directly or through the rod lens 65.
The reflected light, that is, the image information is converted into an electric signal.

The contact type image sensor having such a structure has an advantage that the distance (optical path length) d2 from the document surface G to the photoelectric conversion element array 63 is smaller than that of the reduction type image sensor and no adjustment is required. ing.

Further, a plurality of waveguides for guiding light from the input image to the photoelectric conversion element array are provided, and the pitch of the emitting ends is made narrower than the pitch of the input ends of the waveguides to obtain a reduced image. In an image sensor, a structure in which an optical reflection material (metal thin film) is formed on a dielectric waveguide has been proposed (Japanese Patent Laid-Open No. 60-189256).

[0010]

A reduction type image sensor using a conventional lens system requires a long optical path length between the document surface and the photoelectric conversion element array, and thus it is difficult to miniaturize it. There is a problem that adjustment is required for each unit and it is also weak against vibration.

Further, in the conventional contact type image sensor,
Since the photoelectric conversion element array has the same size as the document width,
There are problems that the S / N ratio of the photoelectric conversion signal is lowered and that high speed operation becomes difficult due to the parasitic capacitance between the wirings.

Further, in the waveguide type reduction image sensor utilizing the reflection of the metal thin film, in order to prevent the light from leaking to the adjacent waveguide, the metal thin film is similarly formed not only on the upper and lower surfaces of the waveguide but also on both side surfaces. It is necessary to form them, which complicates the manufacturing process and lowers the yield.

The present invention has been made in view of the above points, and an object of the present invention is to provide a waveguide-type reduced image sensor having a simple manufacturing process and a high S / N ratio.

[0014]

In order to achieve the above-mentioned object, the present invention is constructed as follows.

That is, a lens array for condensing the light reflected from the document surface and an optical waveguide for arranging the incident end at the condensing position of the lens array and guiding the light incident on the incident end to the photoelectric conversion element are provided. Another feature of the image sensor is that a disturbance light limiting member that limits disturbance light from entering the incident end is provided around the incident end.

A light reflection film may be formed on the disturbance light limiting member.

The optical waveguide may be formed on the waveguide substrate, and the waveguide substrate and the disturbance light limiting member may be formed as an integral molded body.

The optical waveguide and the lens array may be integrally formed.

[0019]

According to the above construction, the disturbance light is blocked by the disturbance light limiting member provided around the entrance end, so that the disturbance light is less likely to be incident on the entrance end.

If a light reflection film is formed on the disturbance light limiting member,
Since the ambient light is reflected by this light reflecting film, the blocking effect is enhanced.

If the optical waveguide is formed on the waveguide substrate and the waveguide substrate and the ambient light limiting member are formed of an integral molded body, they can be assembled as compared with the case where these are individually manufactured and integrated. Adjustment becomes easy.

When the optical waveguide and the lens array are formed of an integrally molded body, assembly and adjustment are easier than in the case where the lens array and the optical waveguide are manufactured separately. Moreover, since the optical waveguide that guides light from the lens array to the photoelectric conversion element can be manufactured in an arbitrary shape, the mutual arrangement positional relationship between the optical waveguide that is the coupling optical system and the photoelectric conversion element becomes arbitrary, and the image sensor It can be miniaturized.

[0023]

Embodiments of the present invention will now be described in detail with reference to the drawings.

The following examples are all 200 dp
This is an example of application to a one-dimensional image sensor for G3 type facsimile (scan width 256 mm: B4 paper compatible) having a resolution of i. The photoelectric conversion element is a CCD of 14 μm pitch and 2048 pixels (NEC Corporation). ) Manufactured by μPD3743D is used.

FIG. 1 is a schematic configuration diagram of an image sensor according to an embodiment of the present invention, FIG. 2 is a plan view centering on a waveguide substrate, and FIG. 3 is a sectional configuration diagram of the image sensor. is there.

The image sensor 1 comprises a microlens array 2, a waveguide substrate 3, a CCD array 4, an LED array 5 and a cover plate 6. The microlens array 2 is, for example, DAI (Diallylisophthalate: refractive index 1.57)
And an optical polyester resin (an example of an amorphous polyester copolymer; "O-PET" manufactured by Kanebo Co., Ltd. [trade name]: refractive index 1.63). The microlens array 2 has the same width as the original surface G, and a plurality of lens portions 2a are formed in parallel along the original surface G on the original contact surface. The lens portion 2a is configured to correspond to the width of the document surface G and the resolution of the image sensor 1,
Specifically, it is composed of spherical lenses having a diameter of 127 μm, and a total of 2048 lenses are provided in this embodiment.

The waveguide substrate 3 has a refractive index lower than that of the microlens array 2, for example, acrylic (PMMA: Polymethyl).
Methacrylate: a rectangular plate having a refractive index of 1.492), which is parallel to each other and faces the input / output end faces 3a,
3b. The microlens array 2 is attached over almost the entire width of the incident end face 3a of the waveguide substrate 3, and the CCD array 4 is attached at the center of the emission end face 3b in the width direction.

The waveguide substrate 3 has the same number (2028) of optical waveguides 7 ... Corresponding to each lens portion 2a. The optical waveguide 7 is configured by filling a capillary 8 which is formed as a groove on one surface 3c of the waveguide substrate 3 with a waveguide core 9, and the optical waveguide 7 is formed on the one surface 3c from the incident end surface 3a to the emitting end surface 3b. It is provided over. The waveguide core 9 is made of the same material as the microlens array 2, that is,
In the above example, it is made of DAI (refractive index 1.57) or optical polyester resin (refractive index 1.63).

The incident ends 7a of the respective optical waveguides 7 are arranged at the same pitch (127 μm pitch) as the lens portion 2a forming pitch so as to face the respective lens portions 2a of the microlens array 2 on the incident end surface 3a of the waveguide substrate 3. Incident surface 3 apart
a It is arranged over the entire width. The focus of each lens portion 2a is set at the position of the incident end 7a of each optical waveguide 7, and the light incident on the lens portion 2a having a diameter of 127 μm is reduced to a diameter of 8 μm and enters the incident end 7a. Has become. Therefore, the optical waveguide 7 has a width of 8 μm and a depth of 8 μm in order to guide the light having a diameter of 8 μm incident on the incident end 7a.
Is formed in a rectangular cross section.

On the other hand, the emitting end 7b of each optical waveguide 7 is spaced at the same pitch as the CCD element forming pitch (14 μm) so that the emitting end 7b faces the CCD elements constituting the CCD array 4 on the emitting end surface 3b. It is arranged in the central portion in the width direction. The midway portion 7c of the optical waveguide is bent at a right angle twice so as to connect the entrance end 7a and the exit end 7b.

Further, the disturbance light limiting member 10 surrounding the incident end 7a of the optical waveguide 7 is provided on the incident end face 3a of the optical waveguide substrate 3.
Is provided. At the center of the disturbance light limiting member 10, there is formed a conical shape, that is, a light passage hole 10a whose entrance end 7a of the optical waveguide 7 is a bottom portion and whose diameter is gradually enlarged toward the lens portion 2a. The bottom of the passage hole 10a is open and faces the incident end 7a. The inclination angle of the wall surface of the light passage hole 10a, that is, the side surface of the disturbance light limiting member 10 on the lens array focusing axis side is set along the focusing angle of the lens portion 2a.

The disturbance light limiting member 10 is formed integrally with the incident end face 3a of the waveguide substrate 3. That is, the disturbance light limiting member 10 is configured by projecting the waveguide substrate 3 from the incident end face 3a to the microlens array 2 side and further outward from the one face (optical waveguide forming face) 3c in the substrate thickness direction. The same material (DAI, optical polyester resin, etc.) as that of the microlens array 2 and the waveguide core 9 is filled in the light passage hole 10a. Therefore, the waveguide core 9 is integrally formed with the microlens array 2 through the resin in the light passage hole 10a.

The incident end face 3a of the waveguide substrate 3 and the top face 10b of the disturbance light limiting member 10 are covered with metal reflection films 11 and 12, and the end face 6a of the cover plate 6 located on the incident end face 3a side is also covered. It is covered with the metal reflection film 13.

The waveguide substrate 3 is the optical waveguide 6 described above.
The size is 260 mm in width × 25 mm in length × thickness of 2 mm so that can be formed.

The cover plate 6 is made of the same acrylic material as the waveguide substrate 3 (PMMA: Polymethyl Methacrylate: refractive index 1.4).
92), and as described above, the incident end face 3a
The lid end surface 6 a located on the side is covered with the metal reflection film 13. The lid plate 6 is attached to the one surface 3c (optical waveguide forming surface) of the waveguide substrate 3 with the lid end surface 6a being in contact with the ambient light limiting member 10. Therefore, the capillaries 8 of the waveguide substrate 3 are closed by the cover plate 6, so that the waveguide core 9 in the optical waveguide 7 has a lower refractive index than the waveguide core 9 and the cover plate 6.
Is surrounded by.

By providing such a disturbance light limiting member 10 and providing metal reflecting films 11, 12, 13 on the top surface 10b thereof, the incident end surface 3a of the waveguide substrate 3 and the end surface 6a of the cover plate 6, it is possible to make adjacent ones. The scattered light is prevented from entering the incident end 7a from the lens portion 2a and causing crosstalk. Details of crosstalk prevention by the ambient light limiting member 10 will be described later.

Incidentally, the structure of the ambient light limiting member 10 may be one shown in FIGS. 7 and 8 in addition to those shown in FIGS. 7 is a sectional view corresponding to FIG. 4, and FIG. 8 is a sectional view corresponding to FIG.

That is, the ambient light limiting member 14 shown in FIGS. 7 and 8 and the ambient light limiting member 10 shown in FIGS. 1 to 6 have different heights, and the ambient light limiting member shown in FIGS. 1
0 has a height H1 (see FIG. 4) that reaches a substantially intermediate position of the distance between the lens portion 2a and the incident end 7a, whereas the disturbance light limiting member 14 shown in FIGS. Two
It has a height H2 (see FIG. 7) that is close to a, and in this respect, the disturbance light limiting members 10 and 14 are first different. At the central position of the ambient light limiting member 14, as in the ambient light limiting member 10, there is a conical shape, that is, the entrance end 7a of the optical waveguide 7 is the bottom portion and its diameter is gradually enlarged toward the lens portion 2a. A light passage hole 14a is formed, and the bottom portion of the light passage hole 14a is open and faces the incident end 7a.

Further, the differences between the ambient light limiting members 10 and 14 are as follows. That is, the ambient light limiting member 1
In addition to providing the metal reflection films 11, 12, 13 on the top surface 14a, the incident end surface 3a of the waveguide substrate 3, and the end surface 6a of the cover plate 4, 4 is the inner peripheral surface of the disturbance light limiting member 14, that is,
The metal reflection film 15 is also formed on the wall surface of the light passage hole 14a.

A tall disturbance light limiting member 1 having a height H2
4 is provided and the metal reflection film 15 is formed in the light passage hole 14a, so that the metal reflection film 15 also blocks the ambient light of the document surface G (light diffusely reflected by the document surface G). As described above, in the structure of the image sensor shown in FIGS. 7 to 8, the metal reflection film 1 provided on the top surface 14 a of the ambient light limiting member 14, the incident end surface 3 a of the waveguide substrate 3, and the end surface 6 a of the cover plate 6.
Not only the disturbance light is blocked by 2, 11, 13 but also the disturbance light is blocked by the metal reflection film 15 formed in the light passing hole 14a by providing the tall disturbance light limiting member 14 having the height H2, With such a structure, crosstalk is prevented.

Next, the manufacturing process of the image sensor 1 will be described. The image sensor 1 is manufactured by a first manufacturing method in which the microlens array 2 and the optical waveguide 7 are formed by using a capillary phenomenon using DAI or the like as a material and injection molding using an optical polyester resin or the like as a material. There is a second manufacturing method for forming the microlens array 2 and the optical waveguide 7. In the following description, a method of manufacturing the image sensor 1 having the low-profile disturbance light limiting member 10 will be described. However, even an image sensor having the high-profile disturbance light limiting member 14 is manufactured by the same method. It goes without saying that you can do it.

First Manufacturing Method First, the waveguide substrate 3 and the cover plate 6 are injection molded. Lid plate 6
Has a rectangular shape with a flat surface, its manufacture can be performed by general injection molding using a mold, and therefore the description of its manufacturing process is omitted.

On the other hand, since the waveguide substrate 3 has a capillary 8 on its surface and is complicated, its mold is formed as follows using the photolithography technique.

That is, as shown in FIG. 9A, a photoresist film 21 having a film thickness of 8 μm is formed on a silicon substrate 20, and a mask 8 having a shape of a capillary 8 is arranged on the photoresist film 21 to emit ultraviolet rays 23. By exposing with
As shown in (b), the mask shape is changed to the photoresist film 2
Transfer to 1. Further, as shown in FIG. 9C, a metal thin film 23 is formed on the surface of the photoresist film 21 by electroplating using an aqueous solution of nickel chloride. And
The mold support 24 is adhered to the surface of the metal thin film 23 using an epoxy-based adhesive. Finally, the metal film 23 is separated from the silicon substrate 20 by dissolving the photoresist film 21 using a resist stripping solution. As a result, as shown in FIG. 9D, the mold 30 for the waveguide substrate 3 including the metal thin film 23 and the metal support 24 is completed.

Further, as shown in FIG. 10, a mold 31 which faces the mold 30 to form a molding space for the waveguide substrate 3 and the disturbance light restricting member 10, and a light passage hole 10a. The core 32 and the core 32 are formed by an injection molding technique. Then, the molds 30 and 31 and the core 32 are assembled, and a molding resin is injected into the mold 32, so that the waveguide substrate 3 and the ambient light limiting member 10 are integrally injection-molded.

The waveguide substrate 3, the ambient light limiting member 10 and the predetermined portions of the cover plate 6 thus manufactured, that is, the incident end face 3a of the waveguide substrate 3, the ambient light limiting member 10 are formed.
The metal reflection films 11, 12, and 13 are formed on the top surface 10b of the substrate and the end surface 6a of the cover plate 6, respectively. The metal reflection films 11, 12, and 13 are formed by evaporating a metal such as aluminum.

The cover plate 6 is bonded to the one surface 3c of the waveguide substrate 3 thus formed. Adhesion is performed by ultrasonic welding, for example.

On the other hand, as shown in FIG. 11, a mold 33 for forming the microlens array 2 is prepared. The mold 33 has a molding space 34 that is a microlens array formed on one surface 33a, and an injection port 35 that communicates with the molding space 34 is opened on the other surface 33b. Then, the incident end surface 3a of the waveguide substrate 3 is brought into contact with the one surface 33a of the mold 33. At this time, the ambient light limiting member 10
Are housed in the molding space 34, and the waveguide substrate 3 is aligned with the mold 33 so that the incident end 7a of each optical waveguide 7 faces the lens portion 2a forming portion of the molding space 34. .

After the waveguide substrate 3 is brought into contact with the mold 33, both are fixed by the clamping jig 36 and integrated. The clamping jig 36 is composed of a jig plate 36a and a tightening screw body 36b. The jig plate 36a is brought into contact with the emitting end face 3b of the waveguide substrate 3 while the jig plate 36a is in contact with the jig plate 36a.
The mold 33 and the waveguide substrate 3 are integrated by connecting and tightening a and the mold 33 with a tightening screw body 36b. At this time, a packing 37 that surrounds the opening of the capillary 8 that serves as the emission end 7b is provided on the waveguide substrate contact surface of the jig plate 36a, while the mold 33 surrounds the molding space 34 and is packed. 38 are provided. Therefore, the capillary 8 and the molding space 34 communicating with the capillary 8 are sealed except for the injection port 35.

The waveguide substrate 3 and the mold 33 thus integrated are inserted into the chamber 39, and the chamber 39
It is held by a holder 40 provided inside. The holder 40 supports the waveguide substrate 3 and the mold 33 so as to be vertically movable.
The chamber 39 contains D containing 5% benzoyl peroxide.
A container 43 containing the AI monomer solution 42 is stored. The container 43 is arranged below the holder 40. The benzoyl peroxide contained in the DAI monomer solution 42 acts as a polymerizing agent for polymerizing the DAI monomer which is heated later.

Next, the inside of the chamber 39 is evacuated to a degree of vacuum of 10 ^-4 Torr, and a degassing process is performed until the gas contained in the DAI monomer solution 42 is removed.
Using the holder 40, the waveguide substrate 3 and the mold 33 are lowered into the container 43, and the injection port 35 of the mold 33 is filled with DA.
Immerse in I monomer solution 42.

After immersing the inlet 35 in the DAI monomer solution 42, the interior of the chamber 39 is leaked so as to gradually change from vacuum to atmospheric pressure, and the pressure in the capillary 8 and the molding space 34 becomes equal to that of the DAI monomer solution 42. Since the pressure is relatively smaller than the pressure applied to the surface, the capillary phenomenon occurs in the negative pressure state, and the DAI monomer solution 42 is sucked into the mold 33 and the capillary 8. In this way, by assisting the inhalation effect of the capillary phenomenon with negative pressure, DAI
The monomer solution 42 can be surely inhaled.

After the mold 33 and the capillary 8 are filled with the DAI monomer solution 42 and the pressure in the chamber 39 reaches the atmospheric pressure, the holder 40 is raised and the mold 33 and the waveguide substrate 3 are clamped. Remove from 36. Then, the die 33 and the waveguide substrate 3 are heated at 85 ° C. for 6 hours by using an oven (not shown) or the like to polymerize the DAI monomer solution 42 therein, that is, solidify.
When the DAI monomer solution 42 is polymerized, the optical waveguide 7 and the microlens array 2 are completed by removing the mold 33 from the waveguide substrate 3 and cutting off the extra injection port portion. Then, the CCD array 4 is attached to the central portion of the emission end face 3b of the waveguide substrate 3 on which the optical waveguide 7 is completed. At this time, CCs are attached to the respective output ends 7b of the optical waveguide 7.
The CCD array 4 is attached so that the CCD elements of the D array 4 face each other.

Second Manufacturing Method Also in this manufacturing method, the manufacturing method of the waveguide substrate 3 and the lid plate 6 is the same as the first manufacturing method, and therefore the description of the manufacturing method is omitted.

In brief, this manufacturing method insert-molds the microlens array 2 and the waveguide core 7 into the waveguide substrate 3, and first, the waveguide substrate 3 and the cover plate 6 are movable. Mold 44 and microlens array 2
A fixed mold 45 for forming is prepared.

The movable die 44 is formed with an accommodation space 44a for accommodating the waveguide substrate 3 and the lid plate 6, and a suction hole 46 for communicating the outside of the die with the part surface A. On the other hand, the fixed die 45 has a molding space 47 for forming a lens array. The molding space 47 is open to the part surface A. Further, the fixed mold 45 is provided with a gate 48 and a sprue 49 for supplying a molding resin into the molding space 47 from the outside of the mold.

Then, the waveguide substrate 3 integrated with the cover plate 6 is housed in the housing space 44a of the movable mold 44, the molds 44 and 45 are joined together, and vacuum suction is performed from the suction hole 46. Then, the molding space 47 and the capillaries 8 of the waveguide substrate 3 are degassed.

After deaeration, the sprue 49 is moved to the molding space 47.
The molten injection resin 50 is injected into the inside. The injection resin 50 is an optical polyester resin (eg, manufactured by Kanebo Co., Ltd.)
O-PET [trade name]: refractive index 1.63) is used. The injected resin 50 is injected into the molding space 4 via the gate 48.
After being filled with 7, it is injected into each capillary 8. At this time, since the inside of the capillary 8 is deaerated, the injected resin 50 reaches the end of the capillary 8 having a small diameter.

The injection resin 50 filled in the molding space 47 and the capillary 8 is forcibly cooled and solidified. When the injected resin 50 is cooled and solidified, the fixed mold 45 and the movable mold 44 are separated, and the excess resin solidified in the gate 48 is cut from the microlens array 2 at the gate position. As a result, the optical waveguide 7 and the microlens array 2 are completed.

Then, the CCD array 4 is attached to the central portion of the emission end face 3b of the waveguide substrate 3 on which the optical waveguide 7 is completed. At this time, C is applied to each of the emitting ends 7b of the optical waveguide 7.
The CCD array 4 is attached so that the CCD elements of the CD array 4 face each other.

By the way, in the above embodiment, the waveguide core 9
As a material suitable for the microlens array 2, DAI (Diallyl Isophthalate: refractive index 1.57) is used in the first manufacturing method, and an optical polyester resin (amorphous polyester copolymer) is used in the second manufacturing method. Example: Kanebo Co., Ltd.
Product "O-PET" [trade name]: refractive index 1.63) was presented. However, the materials of the waveguide core 9 and the microlens array 2 are not limited to these materials, and the following materials may be used. That is, allyl diglycol carbonate (eg; "RAV7" [trade name]: refractive index 1.503 manufactured by Mitsui Petrochemical Co., Ltd.) is suitable for the first manufacturing method utilizing the capillary phenomenon. Further, in the second manufacturing method using the injection molding method, polycarbonate, polyolefin, styrene elastomer and the like are suitable.

Next, the reason why crosstalk occurs between the optical waveguides 7 and the reason why crosstalk can be prevented by providing the disturbance light limiting members 10 and 14 are shown in FIG.
14 will be described.

The numerical aperture NA _a of each lens portion 2a is calculated by the following equation.

NA _a = n ₀ sin α ... n ₀ : optical refractive index of the lens array α: angle formed between the effective aperture position and the focal position of the lens portion 2a (see FIG. 13) In FIG. 14, an incident angle corresponding to the critical angle δ of incident light that is incident on the incident end 7a at the incident angle θ and then at the point k on the interface of the waveguide core 9 at the angle δ (the incident angle θ is larger than this). Then, if the angle (passing through the waveguide core 9 without being reflected at the k point) is θ ₀ , the numerical aperture NA _d of the waveguide 3 can be calculated by the following equation.

NA _d = n ₀ sin θ ₀ = √ (n ₁ ² −n ₂ ² ) ... n ₀ : Optical refractive index outside the waveguide 3 (optical refractive index of the lens array 2 in this case) n ₁ : Waveguide Optical Refractive Index n ₂ of Core 9: Optical Refractive Index of the Waveguide Substrate 3 and the Cover Plate 6 to be Clad Therefore, if the numerical aperture NA _a = NA _d of each lens portion 2 a, the aperture width of the lens portion 2 a (see FIG. The light that has entered inside 13) is focused at the focal position of the lens portion 2a, that is, the incident end 7a, and propagates through the optical waveguide 7 without any problem.

On the other hand, the light is incident on the lens portion 2a from a point P (see FIG. 13) outside the ab range, and the incident end 7a
Since the incident angle θ _{1 of} the light reaches the incident angle θ ₁ is larger than the incident angle θ ₀ corresponding to the critical angle δ of the incident light, the light reaches the inside of the waveguide substrate 3 without passing through the interface of the waveguide core 9. Do not propagate 7.

Further, the light enters the lens portion 2a from a point Q (see FIG. 13) outside the ab range, and further enters the inside of the waveguide substrate 3 from the incident end face 7a which is not the incident end 3a to adjoin the adjacent optical waveguide 7. The light that has reached the side surface of is incident on the adjacent optical waveguide 7. However, the angle δ1 (see FIG. 13) formed by this incident light at the interface j point of the adjacent waveguide core 9 is larger than the incident angle θ ₀ corresponding to the critical angle δ of the interface of the optical waveguide 7. Therefore, the incident light passes through the optical waveguide 7 without being reflected, and does not propagate through the optical waveguide 7.

From the above, the numerical aperture N of the lens portion 2a is N.
If A _a and the numerical aperture NA _d of the optical waveguide 7 are matched, light can be propagated without causing crosstalk. However, in practice, the numerical aperture NA of the lens portion 2a
It is difficult to match _a with the numerical aperture NA _d of the optical waveguide 7. This is because it is almost impossible to align the materials of the lens portion 2a, the waveguide substrate 3, and the waveguide core 9 having the optical refractive indexes that can obtain such numerical apertures NA _a and NA _d .

Therefore, (the numerical aperture NA of the lens portion 2a is
_a )> (numerical aperture NA _d of the optical waveguide 7), the lens portion 2
Although 100% of the light condensed by a cannot be incident on the optical waveguide 7, it is possible to completely prevent the occurrence of crosstalk, by (numerical aperture NA _a of the lens portion 2a) <(optical waveguide 7
As for the numerical aperture NA _d ), although 100% of the light condensed by the lens portion 2a can be incident on the optical waveguide 7, the occurrence of crosstalk must be allowed to some extent. .

In the present invention, (the numerical aperture NA of the lens portion 2a is
_a ) <(numerical aperture NA _d of the optical waveguide 7), the lens portion 2
While 100% of the light condensed by a is made incident on the optical waveguide 7, the disturbance light control members 10 and 14 are provided to prevent the occurrence of crosstalk, whereby the image can be generated without causing crosstalk. The sensitivity of the sensor 1 is improved.

By setting NA _d > NA _a , NA _d
= NA _a , the incident angle θ ₀ corresponding to the critical angle δ is relatively large (the critical angle δ is relatively small), and even if the inner surface of the optical waveguide 7 is rough, the wall surface of the optical waveguide 7 is large. The transmission loss from can be reduced. For the same reason, the transmission loss from the wall surface of the curved portion of the optical waveguide 7 (there are two right-angled bent portions in the midway portion 7c of the optical waveguide 7 as shown in FIG. 2) can be reduced.

Generally, it takes a long processing time to make the processed surface smooth and the processing cost is high, and the image sensor 1 of the present invention which can alleviate such smooth processing.
Thus, it is possible to reduce the processing cost and the processing time accordingly.

Further, in this image sensor 1, since the microlens 2 and the waveguide core 9 are made of the same material, the difference in optical refractive index / temperature between them does not matter.
Further, there is an advantage that interface loss between the lens portion 2a and the optical waveguide 9 is eliminated, and transmission loss can be reduced. This is because the effective refractive index of the optical waveguide depends not only on the waveguide core but also on the refractive index change of the cladding portion, but mainly depends on the waveguide core.

[0074]

As described above, according to the present invention, the disturbance light is blocked by the disturbance light limiting member provided around the incident end, so that crosstalk can be prevented. Therefore, photoelectric conversion efficiency with a high S / N ratio can be obtained.

If a light reflection film is formed on the disturbance light limiting member,
Since the ambient light is reflected by this light reflection film, the blocking effect is enhanced and the crosstalk prevention effect can be enhanced.

When the optical waveguide is formed on the waveguide substrate and the waveguide substrate and the disturbance light limiting member are formed of an integrally molded body, assembly and adjustment can be performed more than when these are individually manufactured and integrated. It has become easier to reduce the manufacturing cost and the manufacturing time.

In the case where the optical waveguide and the lens array are integrally formed, the assembly and adjustment are easier, the manufacturing cost is reduced, and the manufacturing time is shorter than that in the configuration in which the lens array and the optical waveguide are manufactured separately. Can be shortened. Moreover, since the optical waveguide can be manufactured in any shape, the mutual arrangement positional relationship between the optical waveguide that is the coupling optical system and the photoelectric conversion element becomes arbitrary, and the image sensor can be downsized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image sensor according to an embodiment of the present invention.

FIG. 2 is a plan view of the image sensor of the embodiment of FIG.

FIG. 3 is a side view of the image sensor of the embodiment of FIG.

4 is a cross-sectional view taken along the line AA of FIG.

5 is a sectional view taken along line BB of FIG.

FIG. 6 is a perspective view of the image sensor of the embodiment.

7 is a cross-sectional view corresponding to FIG. 4, which is a modified example of the image sensor.

8 is a cross-sectional view corresponding to FIG. 5, which is a modified example of the image sensor.

FIG. 9 is a diagram showing a first-half process of the first manufacturing method, respectively.

FIG. 10 is a diagram showing a configuration of a mold used in a middle stage process of the first manufacturing method.

FIG. 11 is a diagram showing a configuration of a chamber used in a latter step of the first manufacturing method.

FIG. 12 is a cross-sectional view showing the structure of a mold used in the second manufacturing method.

FIG. 13 is a diagram for explaining the reason why crosstalk occurs.

FIG. 14 is a diagram for explaining the reason why crosstalk occurs.

FIG. 15 is a schematic configuration diagram of a first conventional example.

FIG. 16 is a schematic configuration diagram of a second conventional example.

[Explanation of symbols]

 2 Microlens Array 3 Waveguide Substrate 7 Optical Waveguide 7a Incident End 8 Capillary 10 Ambient Light Limiting Member 14 Ambient Light Limiting Member

Claims (6)

[Claims] 1. A lens array for condensing light reflected from an original surface, and an optical waveguide for arranging an incident end at a condensing position of the lens array and guiding the light incident on the incident end to a photoelectric conversion element. In the image sensor, an ambient light limiting member that limits ambient light from entering the incident end is provided around the incident end. 2. The image sensor according to claim 1, wherein a light reflecting film is formed on the disturbance light limiting member. 3. The image sensor according to claim 2, wherein the light reflection film is formed on a side surface of the disturbance light limiting member on the lens array focusing axis side. 4. The image sensor according to claim 1, wherein the side surface of the disturbance light limiting member on the lens array focusing axis is inclined along the focusing angle of the lens array. 5. The image sensor according to claim 1, wherein the optical waveguide is formed on a waveguide substrate, and the waveguide substrate and the disturbance light limiting member are integrally formed. 6. The image sensor according to claim 1, wherein the optical waveguide and the lens array are formed as an integrally molded body.