JPH0574042B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a contact type image sensor suitable for use in facsimile, character, and image reading input devices.

<Conventional technology> In general, text and image reading and input devices using line sensors pass information from a document illuminated with a fluorescent lamp or LED (light emitting diode) array through an optical lens, rod lens array, or optical fiber. It is configured to read two-dimensional information by forming an image on the sensor and moving the original or the sensor. Conventional reading input devices include those that combine a CCD (charge-coupled device) and an optical lens, and those that combine a long image sensor, a rod lens array, and an optical fiber array. be. In particular, the latter, which is called a contact image sensor, has been developed in recent years with the aim of making facsimile machines smaller and cheaper.

<Problems to be Solved by the Invention> However, in most of the above-mentioned contact image sensors, the information of the document is usually imaged onto the sensor through a rod lens array, so there is a natural limit to miniaturization. . In this type, the document and sensor must be separated by the conjugate length of the rod lens array, and the thickness of the unit of the contact type image sensor is usually 20 to 30 mm. Furthermore, since a lens system is used, optical adjustment is required, and there is also the problem of low light transmission rate.

On the other hand, those that use an optical fiber array without using a lens system do not require optical adjustment, have a sufficiently high light transmission rate, and do not focus, making it possible to shorten the length of the optical fiber and making it suitable for ultra-compact design. ing. However, among the light incident on the optical fiber, the light incident at an angle equal to or greater than the aperture angle does not undergo total internal reflection at the interface with the cladding and is transmitted to the adjacent fiber via the cladding. Furthermore, the light that first enters the cladding passes through the cladding core and reaches the exit surface. When transmitting images using an optical fiber array, this light leakage degrades the image quality. Therefore, an absorber was inserted between the optical fibers to absorb this light leakage.
An EAM (Extra Mural Absrption) type optical fiber array has been devised, but when it is used in a contact image sensor, there is a problem in that it cannot illuminate the surface of the document to be read.

The present invention was devised in view of the above problems, and an object of the present invention is to provide an ultra-compact, high-quality contact image sensor that does not require optical adjustment.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a light source that illuminates a document to be read, a light receiving element that converts reflected light from the document into an electrical signal, and a light receiving element that converts light reflected from the document into an electrical signal. and an optical fiber array disposed between the light receiving element and the light receiving element,
The above-mentioned optical fiber array is constructed by laminating two or more types of optical fiber array bodies, one of which has an optical fiber array made of optical fibers whose side surfaces are coated with an absorber.

<Function> As described above, in the present invention, one of the components of the optical fiber array is an optical fiber array consisting of optical fibers whose side surfaces are coated with an absorber, thereby preventing light leakage. is absorbed by the absorber before being incident on the light-receiving element, thereby preventing deterioration of image quality on the surface of the light-receiving element. In addition, by arranging the uncovered optical fiber array side of the other type of absorber on the side of the document to be read, the surface of the document can be easily irradiated. Further, by using a configuration in which two or more types of optical fiber array bodies are bonded together, an optical fiber array as described above can be easily produced. As described above, it is possible to easily provide an ultra-compact, high-quality contact image sensor that does not require optical adjustment.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of a contact type image sensor according to an embodiment of the present invention. In the figure, 1 is a document, 2 is an LED array light source, 3 is a CCD chip as a light receiving element, 4 is an optical fiber array body that does not include an absorber for preventing light leakage, and 5 is each optical fiber to prevent light leakage. Optical fiber array bodies 6 and 7 coated with an absorber are transparent substrates incorporating the above-mentioned optical fiber array bodies 4 and 5, respectively. Further, 8 is an electrode wiring formed on a transparent substrate, and 9 is a bonding medium bump for connecting the wiring on the CCD chip 3 and the electrode wiring 8. With the above configuration, it is possible to easily provide a high-resolution contact image sensor that is ultra-compact, does not require optical adjustment, and is suitable for mass production.

FIG. 2 is an enlarged view of the optical fiber array body 4 without stepping on the absorber, and FIG. 3 is an enlarged view of the optical fiber array body 5 covered with the absorber.
Here, 10 and 12 are optical fiber core parts, 1
1 and 13 are optical fiber cladding parts, and 14 is an absorber for preventing light leakage interposed between each optical fiber cladding. As shown by the light path (arrow) in FIG. 2, in the optical fiber array body 4 without an absorber, out of the light incident on the optical fibers,
The light leaks into the adjacent optical fiber that is incident at an angle greater than the aperture angle. Furthermore, the light that first enters the optical fiber cladding 11 also leaks to the adjacent optical fiber. In the optical fiber array body 5 coated with an absorber to prevent such leakage light, the leakage light is absorbed by the absorber 14 as shown by the light path (arrow) in FIG. 3, and the quality of the transmitted image is reduced. will not decrease.

The present embodiment is constructed as shown in FIG. 1 by using a stack of two different types of optical fiber array bodies as shown in FIG. 4 as an optical fiber array. With this configuration, the light emitted from the light source 2 passes through the transparent substrates 7 and 6 and the optical fiber array 4 that does not include an absorber, and illuminates the original 1. The image information of the illuminated original 1 is first transmitted to the CCD light receiving element 3 through the optical fiber array body 4 which does not include an absorber, and then through the optical fiber array body 5 which includes an absorber. When the image information passes through an optical fiber array that does not contain an absorber, the image is degraded due to leakage light, but when it passes through the next optical fiber array that contains an absorber, the image becomes degraded. , unnecessary leakage light is cut by the absorber,
Only necessary image information is transmitted to the light receiving element side. Therefore, the light emitted from the light source can be effectively irradiated onto the document, and can also be transmitted to the light receiving element without deteriorating the image quality.

Next, a procedure for manufacturing the contact type image sensor having the above configuration will be explained.

For example, a CCD sensor with a resolution of 16 lines/mm and formed to a length of about 70 mm is used as the light receiving element 3.
In order to prevent a decrease in resolution at the joint portion of the light receiving element 3, the light receiving section and the transfer section on the substrate are formed up to the vicinity of the CCD end. Then, the required number of electrode wirings and bonding parts are formed, and Si _x N _1-x ,
A passivation film made of SiO ₂ or the like is formed.

On the other hand, substrates 6 and 7 are formed by sandwiching the optical fiber array bodies 4 and 5 from both sides, and the substrates 6 and 7 are adhered using a photocurable adhesive as shown in FIG. 4 (see FIG. 1). reference). Here, an optical fiber array was used in which each fiber had a diameter of 25 μm and an aperture angle of about 70°. Furthermore, when adhering, by removing air bubbles before photocuring, it is possible to easily and evenly adhere the materials.

Electrode wiring 8 is formed as a thin film on the upper surface of the substrate 7 pasted together as described above using microfabrication technology, and bonding medium bumps 9 are attached to the electrode wiring and bonding portions on the CCD light receiving element 3. It is formed on the wiring 8. Thereafter, the CCD light receiving element 3 and the substrate 7 are bonded together using a bonding tool. Thereafter, a resin adhesive may be used to reinforce the bond and serve as a protective film for the CCD light receiving element 3. Alternatively, the electrode wiring and bonding portion on the light receiving element 3 side and the electrode wiring 8 on the substrate 7 side may be connected by a reflow bonding method using solder bumps as the bonding medium bumps. The reflow bonding method is performed by heating the solder bumps in a belt furnace at 100°C to 350°C to melt them. According to this manufacturing method, alignment using solder bumps is possible, and the elongated light receiving element 3 can be aligned with high productivity due to the self-alignment effect of the solder.

In this way, the connection between the light receiving element 3 and the substrate 7 is as follows.
This is performed both to fix the position of the light receiving element 3 and to electrically connect it. The light receiving elements 3 are arranged in a horizontal row in the longitudinal direction of the substrate 7 so as to have approximately the same length as the original 1. In addition, since an optical fiber array is used instead of an optical lens, the optical path length can be freely selected, making the entire sensor more compact, and eliminating the need for lens focus adjustments, etc., as in conventional methods. Lower prices can also be achieved. Furthermore, since the light-receiving element and the substrate incorporating the optical fiber array can be manufactured separately, production can be achieved with high yield.

Figure 5 shows the resolution (MTF) characteristics of the contact type image sensor manufactured as described above. It can be seen that the contact type image sensor of this example has a structure in which two or more types of optical fiber array bodies are stacked, so that it is not only possible to easily irradiate a document with light, but also has very good resolution (MTF) characteristics.
Furthermore, when a single CLEAR type optical fiber array unit without an absorber is used, the resolution characteristics are extremely poor due to light leakage between each fiber. Furthermore, a single optical fiber array of the type in which each optical fiber is coated with an absorber cannot illuminate the document to be read.

<Effects of the Invention> As explained above, according to the contact type image sensor of the present invention, one of the components of the optical fiber array body has an optical fiber array made of optical fibers coated with an absorber. Since the original can be easily illuminated and leaked light can be reliably cut, very good resolution can be obtained, and it can be easily manufactured. Furthermore, since focus adjustment and the like are not required, ultra-miniaturization and low cost can be realized.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the cross-sectional structure of a contact type image sensor according to an embodiment of the present invention, Fig. 2 is an enlarged view showing the structure of an optical fiber array body that does not include an absorber, and Fig. 3 is an enlarged view showing the structure of an optical fiber array body that does not include an absorber. FIG. 4 is an enlarged view showing the structure of the optical fiber array body, FIG. 4 is an enlarged view showing the laminated structure of the optical fiber array in one embodiment of the present invention, and FIG. 5 is the resolution of the contact type image sensor in one embodiment of the present invention. (MTF) characteristics. 1... Original, 2... LED array light source, 3...
Light receiving element, 4... Optical fiber array body not containing an absorber, 5... Optical fiber array body coated with an absorber, 6, 7... Transparent substrate, 8... Electrode wiring, 9... Bonding medium Bump, 10, 12... Optical fiber core part, 11, 13... Optical fiber clad part, 14... Absorber.

Claims (1)

[Claims] 1. A light source that illuminates the original to be read, a light receiving element that converts the reflected light from the original into an electrical signal,
In a contact type image sensor having an optical fiber array disposed between the original document and the light receiving element, the optical fiber array is formed by laminating two or more types of optical fiber array bodies, and one of the optical fiber array bodies is stacked. The type of contact image sensor is characterized by having an optical fiber array consisting of optical fibers whose sides are coated with an absorber.