JPH0542402Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a contact type image sensor, and more specifically, to a contact type image sensor suitable for use in, for example, facsimile, text, image reading input devices, etc. .

<Prior art> In general, text/image reading/input devices using line sensors read information from documents illuminated by fluorescent lights, LED (light emitting diode) arrays, etc.
It is configured to form an image on a line sensor through an optical lens, a rod lens array, an optical fiber, or the like, and read two-dimensional information by moving the original or the line sensor in one direction. Conventional reading input devices of this type are
There are configurations that combine a CCD (charge-coupled device) and an optical lens, and configurations that combine a long image sensor and a rod lens array or optical fiber array. In particular, the latter type of image sensor, which is called a contact type image sensor, has been developed in recent years with the aim of downsizing and lowering the cost of facsimile devices and the like.

However, among the above-described contact type image sensors, those using a rod lens array have a limit to miniaturization because the information of the document is imaged onto the sensor through the rod lens array.
The document sensor must be separated by the conjugate length of the rod lens array, and the thickness of the entire device is 20 to 30 mm.
I end up becoming mm. Since a lens system is used, optical adjustment is required. The light transmission rate of the lens system is quite low. There were other problems.

On the other hand, a device using an optical fiber array without using a lens system requires no optical adjustment and has a sufficiently high light transmission rate. Since it is not a lens, the length of the optical fiber can be shortened, making it suitable for ultra-miniaturization. There are advantages such as

<Problems to be Solved by the Invention> However, in the device using the above optical fiber array, it is difficult to bond the light receiving surface of the light receiving element and the light emitting surface of the optical fiber array so that they face each other in close contact with each other. Furthermore, when a light emitting diode array light source is used, there is a limit to miniaturization because a rod-shaped lens is usually used in combination, and if a rod-shaped lens is used, the unevenness of the amount of light in the line direction becomes larger than when not used.

The present invention was devised in view of these circumstances, and aims 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-mentioned object, the present invention includes a housing, a light emitting diode array light source provided in the housing for illuminating a document to be read, and a light emitting diode array light source for illuminating the document to be read. a first optical fiber array body consisting of a light receiving element that converts into an electric signal, and optical fibers each individually coated with an absorber;
a second optical fiber array body made of optical fibers not covered with an absorber; the first optical fiber array body is placed on the side of the light receiving element, and the second optical fiber array body is placed on the side of the original document. The light-receiving element is stacked so as to be arranged between the light-receiving element and the document, and the light-receiving surface of the light-receiving element is in close contact with the light-emitting surface of the first optical fiber array. This is a close-contact image sensor.

<Function> As described above, in the present invention, the optical fiber array is constructed by laminating and bonding an optical fiber array body in which each optical fiber is coated with an absorber and an optical fiber array body in which the absorber is not coated. Therefore, light leakage is absorbed by the absorber before it enters the photodetector, preventing deterioration of image quality on the photodetector surface, and it is necessary to read the side of the optical fiber array body that is not covered by the absorber. By placing it on the document side, the surface of the document can be easily illuminated by the light emitting diode array light source provided within the housing. Therefore, there is no need for optical adjustment, the light transmission rate is sufficiently high, there is no need for a lens system such as a rod-shaped lens between the light emitting diode array light source and the original, miniaturization is possible, and the unevenness of the light amount is small. Become. This is because the light emitted from each light emitting diode array light source becomes diverging light by not using a lens, and uneven light emission is alleviated on the document surface. Furthermore, since each optical fiber in an optical fiber array can be easily made into a minute diameter,
High resolution can be easily achieved.

<Examples> The present invention will be described in detail below based on examples shown in the drawings, but the present invention is not limited thereto.

FIG. 1 is a sectional view of a contact type image sensor according to an embodiment of the present invention, and FIG. 2 is an enlarged view of an optical fiber array.

In Figure 1, 1 is a document, 2 is an LED array light source without a rod lens, 3 is a CCD chip as a light receiving element,
4 is an optical fiber array without an absorber on each optical fiber wall, 5 is an optical fiber array with an absorber on each optical fiber wall, and 6 and 7 are optical fiber arrays incorporating the respective optical fiber arrays 4 and 5. It is a board. 8 is an electrode wiring formed on the transparent substrate 7, 9 is a bonding medium bump for connecting the wiring on the CCD chip 3 and the electrode wiring 8, and 10 is a substrate on which the LED array light source 2 is mounted. ,
11 is a resistor mounted on the substrate 10, 12 is a heat sink for the housing and LED array 2, 13 is a heat sink for the CCD chip 3, and 14 is a flexible printed circuit board for connecting and drawing out the electrode wiring 8, and is a plate-shaped An LED array light source 2 is provided in a housing 12 having a recessed portion, and a translucent substrate 6 is provided in an opening of the housing 12 so as to face the document 1.

As described above, an LED array light source 2 without a rod lens (e.g., emission peak wavelength 570 nm) is used as the light source, and the illumination is made uniform while the sensor unit is made small (e.g., thickness 7 mm, width 19 mm, length 50 mm). This results in an ultra-small, high-resolution contact image sensor that does not require optical adjustment and is suitable for mass production.

In FIG. 2, 15 and 18 are the optical fiber cores 16 and 1 of the fiber bodies 4 and 5, respectively.
Reference numerals 9 denote optical fiber claddings of the fiber bodies 4 and 5, respectively, and numeral 17 denotes an absorber coated on each optical fiber of the fiber body 5. The arrows indicate how light scattered by the original is transmitted to the sensor side.
Of the light that enters the optical fiber core 15, the light that enters at an angle equal to or greater than the aperture angle does not cause total internal reflection at the interface with the optical fiber cladding 16, but leaks to the adjacent optical fiber and transmits an image. However, by using the configuration shown in Figure 2, leakage light can be absorbed by the absorber 1.
You can cut at 7 to prevent the image quality from deteriorating.
In addition, document illumination can be easily performed.

Figure 3 shows the resolution characteristics that were actually evaluated in this configuration.
Very good MTF of 50%. For reference, the broken line also shows the resolution characteristics of a single rod lens array (SLA20), which is often used in conventional contact-type image sensors. In the case of a contact type image sensor using the rod lens array mentioned above, the resolution is worse than that of the rod lens array alone.
It can be seen that the resolution characteristics of the contact type image sensor of the present invention are extremely good.

Next, a procedure for manufacturing a contact type image sensor according to an embodiment of the present invention having the configuration shown in FIG. 1 will be explained.

In this example, the light receiving element 3 has a resolution of 16 lines/mm and is formed to have a length of about 70 mm.
A CCD sensor having the structure shown in FIG.
Form up to near the edge of the CCD. And electrode wiring 2
4 and the required number of joint parts 25, and the light receiving part 2
2 and the transfer section 23, on the light receiving surface of the light receiving element 3,
A passivation film 26 made of Si _x N _1-x , SiO _2, etc. is formed using thin film technology.

On the other hand, fiber array substrates 6 and 7 are formed by sandwiching the optical fiber array bodies 4 and 5 from both sides, and a transparent substrate 7 incorporating the optical fiber array body 5 coated with the absorber 17 and the absorber are coated. A light-transmitting substrate 6 incorporating an optical fiber array body 4 is attached using a photocurable adhesive. Here, the diameter of each optical fiber is 25μm,
An optical fiber array with an aperture angle of approximately 70° was used.
By removing air bubbles before photocuring, it is possible to easily and evenly bond the adhesive. Electrode wiring 8 is formed using microfabrication technology on the side of the transparent substrate 7 that has the absorber of the substrates pasted together as described above, and then a ceramic plate is used as the heat dissipation plate 13 of the CCD chip 3. , CCD chip 3 is bonded onto this ceramic plate using conductive paste. this
Au balls are formed using a ball bonder on the electrode wiring 24 of the CCD chip 3 and the electrode pads of the joint portion 25 to form bonding medium bumps 9, and conductive paste is applied thereon to form the above-mentioned light-transmitting material. It is bonded to the electrode wiring 8 formed on the substrate 7. Furthermore, a resin adhesive is used to reinforce the bond and to serve as a protective film for the CCD chip 3. The electrical connection between the CCD chip 3 and the electrical wiring 8 is made by reflow bonding using solder bumps as bonding medium bumps to connect the electrode wiring 24 and joint 25 on the light receiving element 3 side and the electrode on the substrate 7 side. It may also be connected to the wiring 8. 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-bonding 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. As shown in FIG. 5, the light receiving elements 3 are arranged in a row in the longitudinal direction of the substrate 7 so as to have approximately the same length as the original 1. As shown in FIG.

Next, a flexible printed circuit board 14 for drawing out the wiring from the electrode wiring 8 is connected with solder or a conductive film, and the pasted transparent substrates 6 and 7 are fixed to the metal housing 12 to complete the sensor area. do. Next, the substrate 10 on which the LED array 2 is mounted is mounted in a recessed housing 12 as shown in FIG. 1, and the housing 12 is used as a heat sink for the LED array 2. In addition, it does not use rod-shaped lenses that are commonly used in LED arrays, making it extremely compact. Since an optical fiber array is used in the optical system, the light transmission rate is sufficiently large.
Sufficient illuminance on the sensor surface can be obtained without using a rod-shaped lens. When using an LED array with a peak wavelength of 570 nm, a sensor surface illuminance of 100 lx was obtained.
Furthermore, not using a lens system such as a rod-shaped lens has the advantage that the unevenness of light emission on the document surface is reduced.

Note that when mounting the light receiving element 3 on the light-transmitting substrate 7, it is not limited to the one shown in FIG. 1 above, and as shown in FIGS.
The chip 3 is mounted on a transparent substrate 31, an electrode wiring 81 is formed on the transparent substrate 31, and the electrode wiring 81 and the wiring on the CCD chip 3 are connected by a wire bond portion 32. It goes without saying that the objects may be placed in close contact with each other on the substrate 7.

<Effects of the Invention> As explained above, according to the contact type image sensor of the present invention, it is possible to obtain a contact type image sensor that is ultra-small, easy to manufacture, and has high resolution.

[Brief explanation of the drawing]

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 the optical fiber array section, and Fig. 3 is a diagram showing the resolution characteristics of the contact type image sensor of the present invention. A characteristic diagram showing
4a and 4b are plan views and cross-sectional views showing an example of the structure of a light receiving element, FIG. 5 is a diagram showing an arrangement structure of a light receiving element in one embodiment of the present invention, and FIG. 6 is another embodiment of the present invention. FIG. 7 is a diagram showing the cross-sectional structure of the contact type image sensor as an example, and FIG. 7 is a diagram showing the structure of the light receiving element of the sensor shown in FIG. 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, 10... LED array Mounting board, 12...housing, 13...heat sink.

Claims (1)

[Scope of Claim for Utility Model Registration] A housing, a light emitting diode array light source installed in the housing that illuminates a document to be read, and a light receiving element that converts reflected light from the document into an electrical signal, each of which individually absorbs light. a first optical fiber array body made of optical fibers covered with an absorber; and a second optical fiber array body made of optical fibers not covered with an absorber; The second optical fiber array body is stacked on the element side so as to face the original document, and is arranged between the light receiving element and the original document, and the light of the first optical fiber array body is stacked so as to face the original document side. A close-contact image sensor characterized in that a light-receiving surface of the light-receiving element is brought into close contact with an output surface of the light-receiving element.