JPH01172804A - Contact type image sensor - Google Patents

Abstract

PURPOSE:To obtain the extremely small image sensor of high picture quality by laminating >=2 kinds of optical fiber array bodies between a document and a photodetecting element. CONSTITUTION:The image sensor consists of an LED array light source 2 which lights the document 1, a CCD chip as the photodetecting element 3, etc. In an optical fiber array body 4 which does not have absorbers 14, light incident on an optical fiber 10 at an angle larger than an aperture angle leaks to an adjacent fiber 10 and light incident on an optical fiber clad 11 firstly also leaks to the adjacent optical fiber as shown by the path (arrow) of light. In the optical fiber array body 5 coated with the absorbers 4 for prevention against leak light, the leak light is absorbed by the absorbers 4. Thus, >=2 kinds of optical fiber array bodies 4 and 5 are laminated to easily light the document 1 and the leak light is securely cut off. Consequently, excellent resolution is obtained and the extremely small and low-cost constitution is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a contact type image sensor suitable for use in a facsimile IJ or a character two-image reading/input device.

<Prior art> In general, in a single character image reading input device using a line sensor, information from a document illuminated with a fluorescent lamp or LED (light emitting diode) array is transmitted onto the sensor through an optical lens, rod lens array, or optical fiber. The device is configured to read two-dimensional information by forming an image on the document and moving the document or sensor. Conventional reading input devices of this type 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. 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 many 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 limit to miniaturization. Ta.

In this type, it is necessary to separate the original from the sensor 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 it uses a lens system, optical adjustment is required.
Another problem was that the light transmission rate was low.

On the other hand, those that use an optical fiber array without 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 designs. There is. However, among the light that enters the optical fiber, the light that enters 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 an image using an optical 7-eye bar array, this light leakage deteriorates the image quality. Therefore, in order to absorb this light leakage, an EMA (Extra Mu
ral absorption) type optical fiber arrays have been devised, but when used in contact type image sensors, there is a problem in that the surface of the document to be read cannot be illuminated.

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 light reflected from the document into an electrical signal, and a light receiving element that converts light reflected from the document into an electrical signal. In the contact type image sensor, the optical fiber array has a structure in which two or more types of optical fiber array bodies are laminated.

Function> As described above, in the present invention, by covering all or part of each optical fiber in one type of optical fiber array body with an absorber, leakage of light is prevented from entering the light receiving element. It is possible to prevent the image quality from being degraded on the light receiving element surface by being absorbed by the absorber before being absorbed. In addition, by arranging the uncoated 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 illuminated. 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 same figure, 1 is the original, 2 is the LED
3 is an 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 an optical fiber array body in which each fiber is coated with an absorber for preventing light leakage. , 6 and 7 are transparent substrates incorporating the respective optical fiber array bodies 4 and 5 described above. 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 4 that does not include the above absorber, and FIG. 3 is an enlarged view of the optical fiber array 5 that is coated with the above absorber.

Here, 10 and 12 are optical fiber core parts, 11 and 13 are optical fiber clad parts, and 14 is an absorber for preventing light leakage interposed between each optical fiber clad.

As shown by the light path (arrow) in FIG. 2, in the optical fiber array 4 without an absorber, among the light incident on the optical fibers, the light incident at an angle equal to or greater than the aperture angle leaks into adjacent optical fibers. Moreover, 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. It will not be lowered.

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 the original 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 first passes through an optical fiber array 4 that does not include an absorber, then passes through an optical fiber array 5 that includes an absorber, and is transmitted to the CCD light receiving element 3. 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 by passing through the next optical fiber array that includes an absorber, unnecessary information is removed. Leakage light is cut by the absorber, and only the necessary image information is transmitted to the light receiving element. Therefore, the irradiation light 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/1MR and formed to a length of approximately 70 lines is used as the light receiving element 3, and in order to prevent the resolution from decreasing at the seam part of the light receiving element 3, the light receiving part and the transfer part on the substrate are connected. is formed up to near the end of the CCD. Then, a required number of electrode wirings and bonding parts are formed, and a passivation film made of S I

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.
(see figure). Here, an optical fiber array with each fiber diameter of 25 μm and an aperture angle of about 70° was used. 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 substrates 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. After that, C.C.
The D 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 70-pounding method is carried out by heating the solder bumps in a belt furnace at 100 DEG C. to 350 DEG C. to melt the solder bumps. 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 performed both for fixing the position of the light receiving element 3 and for electrical connection.

The light receiving elements 8 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. Pricing 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.

FIG. 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, and thus not only can light be easily irradiated onto the document, but also the resolution (MTF) characteristics are very good. Furthermore, when a single CLEAR type optical fiber array without an absorber is used, the resolution characteristics are very poor due to light leakage between each fiber. Also,
An optical fiber array of the type in which each 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, the structure in which two or more types of optical fiber array bodies are stacked allows the document to be easily illuminated and leakage light to be reliably cut. It provides very good resolution and is easy to manufacture. Furthermore, since focus adjustment and the like are not required, ultra-miniaturization and low cost can be realized.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a 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 an optical fiber array covered with an absorber. FIG. 4 is an enlarged view showing the structure of the array body. FIG. 4 is an enlarged view showing the laminated structure of the optical fiber array in one embodiment of the present invention. FIG. 5 is the resolution (MTF) of the contact type image sensor in one embodiment of the present invention. FIG. 3 is a diagram showing characteristics. DESCRIPTION OF SYMBOLS 1... Original document, 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...
Coupling medium bump, 10.12... Optical fiber core part, 11°13... Optical fiber cladding part, 14...
·Absorber. Agent Patent Attorney Takeshi Sugiyama (1 other person) Figure 87 Atsushi Figure 2 -3FjU34 Figure

Claims (1)

[Claims] 1. 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 an optical fiber array disposed between the document and the light-receiving element. A close-contact image sensor, characterized in that the optical fiber array is formed by laminating two or more types of optical fiber array bodies. 2. The contact type image sensor according to claim 1, wherein one type of the optical fiber array body is formed by covering all or part of each optical fiber with an absorber.