JP3146401B2 - Image sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called close contact type image sensor used for reading a document surface as image information, for example, in a facsimile or image reader.

[0002]

2. Description of the Related Art The general structure of a conventional contact image sensor is shown in FIG. In the image sensor 1, a document is brought into direct contact with a transparent plate 3 provided on one surface of a frame 2, and reflected light from the document surface receiving light from a light emitting element 4 disposed in the frame is received by a light receiving element 5 in the frame. It is configured to collect light. More specifically, the light emitting element 4 is disposed so as to irradiate illumination light in a diagonal direction toward a document reading unit at a portion relatively close to the document surface in order to increase the illumination efficiency of the document surface, Light reflected from the reading unit is condensed by the lens array 6 whose optical axis is arranged in the thickness direction of the frame 2 on the light receiving element 5 arranged on the substrate at the lower part of the frame at an erect equal magnification. Have been.

The light receiving elements 5 are bonded to a substrate 7 in a bare chip shape, and wire bonding is performed between each light receiving element and a wiring pattern in a substrate shape. The wiring patterns on the board are collected on a part of the board, and are connected to external wirings via a commercially available connector or the like.

[0004] By the way, the demand for downsizing and lightening of devices such as facsimile machines and image sensors is still strong, and therefore, the downsizing of such contact type image sensors is also demanded. At the same time, with the spread of home facsimile machines, further lower prices are also required. In view of such a demand, the image sensor having the structure shown in FIG. 5 of the present application has the following problems.

[0005] The first problem is that the image sensor itself,
This means that it has a considerable size in the thickness direction, which hinders miniaturization of equipment such as a facsimile in which such an image sensor is incorporated. The most important factor requiring a certain size or more in the thickness direction of the image sensor shown in FIG. 5 is that the lens array 6 is used to converge the reflected light from the document surface to the light receiving element at an equal magnification. That is. This lens array 6
Requires a constant conjugate length in addition to the length of the main lens due to its characteristics. Therefore, the distance from the document surface to the light receiving element must be set to a distance corresponding to the conjugate length of the lens array. As described above, the conventional contact-type image sensor has a problem that the use of the lens array 6 causes an increase in the size in the thickness direction.

The second problem is that the number of parts is large,
In addition, the number of assembling steps also increases, which leads to an increase in cost. As can be seen from FIG. 5, a frame 2, a lens array 6, a light emitting element 4, and a board on which the same is mounted, and further a light receiving element and a board on which the same are mounted are required. The steps for assembling are also very complicated.

The present invention has been conceived in view of the above circumstances, and solves the above-mentioned problems of the conventional contact type image sensor at a stroke, further reducing the size and increasing the number of parts. An object of the present invention is to provide an image sensor capable of achieving cost reduction due to reduction.

[0008]

Means for Solving the Problems In order to solve the above problems, the present invention takes the following technical means. That is, in the image sensor described in claim 1 of the present application, a fiber array section in which a large number of optical fibers extending in the thickness direction are densely arranged on a transparent plate is integrally formed with a predetermined width in a straight line in the longitudinal direction. A fiber array plate, a light receiving element mounted on a back surface of the fiber array plate such that a light receiving portion overlaps the fiber array portion, and a light receiving element on a front surface of the fiber array plate. A document reading unit positioned to correspond to the above, a light emitting element mounted at an appropriate position on the back of the fiber array plate, and the fiber array
An electronic circuit mounted on an appropriate position on the back surface of the plate and processing the signal from the light receiving element, and arranged to cover the back side of the fiber array plate, reflecting the light emitted from the light emitting element and reflecting the light emitted from the light emitting element. the document reading section, the back side or these fiber array plate, the fiber array
And a chassis having a reflection surface for illuminating through a transparent plate forming material surrounding the optical fiber in the portion ( a).

[0009]

[0010] Further, as the light emitting element, a bare chip-shaped LED is bonded to an appropriate position on the back surface of the fiber array plate so as to be turned sideways.

[0011]

The fiber array plate basically has a fiber array section in which a large number of optical fibers extending in the thickness direction are densely arranged on a part of a transparent glass plate having a constant thickness. It is formed integrally with a predetermined width in a straight line in the longitudinal direction. The optical fibers are, for example, about 25 μm in diameter, and are densely arranged such that the axis thereof is oriented in the thickness direction of the plate. Both ends of each optical fiber are exposed at both ends of the fiber array plate. Therefore, on one side of the fiber array unit, the light incident on one end of each unit optical fiber is transmitted as it is to the other end of the fiber array unit through each optical fiber. However, with respect to each optical fiber, only the light incident from one end is transmitted to the other end.Preferably, the surface of each unit fiber is provided with a light-shielding coating, and the light is applied through the surface of the fiber. Light is prevented from transmitting inside and outside.

However, in the above-mentioned fiber array section, although the optical fibers are densely arranged, the gap between the fibers is filled with a transparent glass. It has something.

The light emitted from the light emitting element mounted on the back surface of the fiber array plate is reflected on the inner surface of the chassis and passes through the transparent portion of the fiber array plate to the original surface located on the front surface side. Irradiated. The light reflected from the original surface is transmitted to the light receiving unit on the light receiving element mounted on the back surface of the fiber array plate via each optical fiber constituting the fiber array unit. The fiber array section is formed linearly in the longitudinal direction of the fiber array plate, and the light receiving elements are also linearly arranged corresponding to the extending direction of the fiber array section. That is, at each point in the main scanning direction having a length corresponding to the document width, the intensity of the reflected light from the document is transmitted to the light receiving portion on the light receiving element through the optical fiber as it is.

The information on the intensity of light at various points in the main scanning direction received by the light receiving section is converted into an electric signal as image information, and similarly processed by an electronic circuit mounted on the back surface of the fiber array plate. .

As described above, the reflected light from the document surface is
Light is received by a light receiving element directly mounted on the back surface of the fiber array plate through the fiber array portion of the fiber array plate. That is, the path of the reflected light from the document surface to the light receiving element is limited to a distance corresponding to the thickness of the fiber array plate. Compared with the conventional image sensor shown in FIG. 5, the distance corresponding to the conjugate length of the lens array is reduced to the thickness of the fiber array plate in the present invention, and as a result, According to the invention, the size of the image sensor in the thickness direction is significantly reduced as compared with the general image sensor shown in FIG. As a result, the size of a device such as a facsimile device incorporating the image sensor of the present invention is significantly reduced, which greatly contributes to downsizing of the device.

Further, necessary electronic parts, namely, a light emitting element for emitting light for illuminating the document surface with illumination light, a light receiving element for receiving reflected light from the document surface, and supplying power to these light emitting elements and light receiving element; Alternatively, all the electronic circuits that process and control the signals are mounted on the fiber array plate, so in the final assembly stage,
Only assembling such a fiber array plate and a chassis greatly simplifies parts management and the assembly process. The cost reduction effect due to this is very large.

Further, since the light from the light emitting element mounted on the back surface of the fiber array plate at an appropriate position is reflected by the reflection surface formed on the inner surface of the chassis, the document surface is illuminated. Due to the reflection, the illumination light is uniformly applied to the document surface in the main scanning direction, and even if the number of light receiving elements is reduced, the illumination of the document surface in the main scanning direction can be made uniform without any problem. In addition, cost reduction by reducing the number of light emitting elements can be expected.

As described above, according to the image sensor of the present invention, remarkable downsizing and cost reduction can be achieved at the same time.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.
This will be specifically described with reference to the drawings.

FIG. 1 shows a cross section of an example of the image sensor 10 of the present invention. Reference numeral 11 denotes a fiber array plate, on which the light emitting element 1
2, a light receiving element 13 and an electronic component 14 are mounted. A chassis 15 is assembled on the back side of the fiber array plate 11. The image sensor 1 has a predetermined length in a direction orthogonal to the plane of FIG. 1 according to the width of the document to be read.

The fiber array plate 11 is
Basically, it is a transparent plate made of glass or the like, and a fiber array portion 16 in which a large number of optical fibers extending in the thickness direction of the plate 11 are densely arranged at a middle portion in the width direction thereof has a predetermined width. , And are integrally formed linearly in the longitudinal direction of the plate 11. The optical fiber 17 for forming the fiber array section 16 has a diameter of, for example, about 25 μm, and preferably has a non-light-transmitting coating on its peripheral surface.

Although the optical fibers 17 are densely arranged as shown in detail in FIG. 3, glass enters the gap between the fibers. Light transmission through the glass is possible.

An area closer to one side in the width direction of the fiber array section 16 is an original reading section 18, and an original 20 backed up by a platen 19 or the like is brought into contact with the running state.

The light receiving element 13 is mounted on the back surface of the fiber array plate 11 corresponding to the document reading section 18. As the light receiving element 13, an image sensor chip in an array in which a plurality of photodiode elements or phototransistor elements are formed in a row on a silicon wafer is preferably used. Then, as shown in detail in FIG. 2, the light receiving portion 13a of the image sensor chip is mounted on the back surface of the fiber array plate 11 by a flip chip method so as to correspond to the document reading portion 18. Therefore, in this case, wire bonding between the image sensor chip (13) and a wiring pattern (not shown) formed on the back surface of the fiber array plate 11 is unnecessary. The image sensor chip (13) is protected by the resin.

The light receiving element 13 may be a CCD or a photosensitive thin film such as amorphous silicon or cadmium selenium in addition to the image sensor chip described above.

The light emitting element 12 is mounted on the rear surface of the fiber array plate 11 at a position displaced to one side in the width direction from the position where the light receiving element 13 is provided. The light emitting element 12 is a bare chip LED
May be bonded, or an LED element in which an LED chip is resin-molded may be used.

However, when a bare chip LED chip is used, as shown in detail in FIG. 4, the chip (12) is arranged horizontally, and the P-type portion and the N-type portion are respectively formed on the fiber array plate. When bonding to the wiring pattern on the back surface using the conductive paste 21, sufficient light emitted from the PN junction is radiated to the surroundings,
This is advantageous because the illumination efficiency is increased and the reliability can be improved by eliminating the need for wire bonding.

On the other hand, the fiber array plate 1
In a region opposite to the light emitting element 12 with respect to a portion on the back surface of the light receiving element 13 where the light receiving element 13 is provided, supply of power to the light emitting element 12, signal processing from the light receiving element 13, or An electronic component 14 for performing control is mounted.

As apparent from the above description, a predetermined wiring pattern is formed on the back surface of the fiber array plate 11 by sputtering, printing, baking, or the like.

The chassis 15 assembled so as to cover the back side of the fiber array plate 11 includes:
The fiber array plate 11 is formed in a cross-sectional shape that receives both ends in the width direction of the fiber array plate 11 and that conveniently covers the electronic circuit 14, the light emitting element 12, and the light receiving element 13, and is formed by extrusion molding of aluminum, resin, or the like. It can be suitably manufactured by resin injection molding. On the back surface of the fiber array plate 11, the chassis 15 has a partition 22 in contact with a middle part in the back surface width direction of the fiber array plate, and a first space 23 for housing the electronic component 14; Second space 24 for housing element 12 and light receiving element 13
And is divided into The rear surface of the chassis 15 in the second space 24 has two reflection surfaces 2 as shown in FIG.
5, 26 are formed. As the reflection surfaces 25 and 26, the chassis 15 can be simply formed of a white resin, and if necessary, mirror reflection surfaces can be formed by depositing aluminum or the like.

Of the illumination light emitted by the light emitting element 12,
As shown in FIG. 1, the light directed in the vertical direction is reflected twice on the reflection surfaces 25 and 26 on the inner surface of the chassis 15 and basically transmits through the fiber array plate 11 having a light transmitting property. An original is illuminated on an original 20 in a reading unit 18. The light that reaches the document reading section 18 along the above-described path obliquely crosses the fiber array section 16, but as described above, the fiber array section basically has a light transmitting property. Therefore, light can be transmitted through the above-described path.

The light reflected from the original 20 at the original reading section 18 enters from one end of each optical fiber 17 forming the fiber array section 16 and reaches the other end.
At the other end of the optical fiber 17 (on the back side of the fiber array plate 11), there is no useless space, and the light receiving portion 13a of the light receiving element 13 is located immediately, and light enters the light receiving portion 13a. . Since the light receiving element 13 is formed by mounting a plurality of chips in an array having a large number of light receiving elements described above in the main scanning direction, the density of the document surface at each portion in the main scanning direction is the same as that of the fiber. Array part 1
6 to the light receiving element 13. Light receiving element 13
Converts the density of the document surface into an electrical signal as image information in the main scanning direction, is input to the electronic component, and is subjected to signal processing.

As described above, in the image sensor of the present invention, in the assembling stage, the number of components is basically two, that is, the fiber array plate 11 on which each electronic component is mounted and the chassis 15. Final assembly can be performed very simply.

A lens array having a predetermined conjugate length in the conventional image sensor shown in FIG.
Fiber integrated into array plate thickness range
Since the image sensor 10 is replaced by the array unit 16, there is a remarkable effect of shortening the dimension of the entire image sensor 10 in the thickness direction. For example, by setting the thickness of the fiber array plate to 0.8 mm, it is not impossible to reduce the thickness of the entire image sensor to 5 mm or less.
This further promotes downsizing of optical reading devices such as an image reader and a facsimile in which such an image sensor is to be incorporated, especially thinning in the thickness direction.

Further, since the light from the light emitting element 12 is applied to the original surface after a plurality of reflections, the light emitting element 12 is provided discretely in the longitudinal direction of the image sensor due to the light diffusion effect therebetween. Even if this is the case, the light amount in the document reading unit can be averaged in the main scanning direction. This can contribute to improving the reading performance as an image sensor, and can also be expected to reduce costs by reducing the number of light emitting elements 12. As described above, by bonding a bare chip-shaped LED horizontally as the light-emitting element, the illumination efficiency of one LED element is increased. Thus, even if the number of LEDs is reduced, sufficient illumination can be achieved. You can do it.

Of course, the scope of the present invention is not limited to the embodiment described above. As already described, the specific types of the light emitting element 12 and the light receiving element 13 are not particularly limited.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view of an example of an image sensor of the present invention.

FIG. 2 is an enlarged detailed view of a fiber array section in a fiber array plate.

FIG. 3 is an enlarged plan view of the fiber array section.

FIG. 4 is an enlarged perspective view showing a mounting example of a light receiving element.

FIG. 5 is a sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image sensor 11 Fiber array plate 12 Light emitting element 13 Light receiving element 14 Electronic component 15 Chassis 16 Fiber array part

Claims (2)

(57) [Claims] A fiber array plate in which a plurality of optical fibers extending in a thickness direction of the transparent plate are densely arranged on a transparent plate; A light receiving element mounted on the back surface of the fiber array plate so that a light receiving part overlaps the fiber array part; and an original reading device positioned on the front surface of the fiber array plate so as to correspond to the light receiving element. A light-emitting element mounted on a back surface of the fiber array plate, an electronic circuit mounted on a back surface of the fiber array plate, and processing a signal from the light-receiving element; plate is disposed so as to cover the back side of the document reading section and reflects the light emitted from the light emitting element, phi Back side or these array plate, the optical fibers in the fiber array unit
An image sensor, comprising: a chassis having a reflection surface for illuminating through a surrounding transparent plate forming material . 2. The light emitting element is a bare chip LED.
2. The image sensor according to claim 1 , wherein the image sensor is arranged sideways.