JPH0511825B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a contact type image sensor, and is used, for example, in facsimile devices, character/image reading input devices, and the like. (Prior Art) In general, a character/image reading/input device using a line sensor reads information on a document illuminated by a fluorescent lamp, an LED (light emitting diode) array, 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 and sensor must be separated by the conjugate length of the rod lens array, and the thickness of the entire device is 20~20 mm.
It becomes 30mm. 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 FIGS. 6a and 6b show the conventional structure of an optical fiber array portion of a contact type image sensor using optical fibers. Figure a shows a Clear type (no absorber) optical fiber array, Figure b shows an EMA (Extra type) optical fiber array.
Each figure shows a Mural Absorption type optical fiber array. In the figures a and b, a is an optical fiber, b is an optical fiber cladding, c is an absorber interposed between the optical fibers a, a, . . . over the entire length, and d is a light exit surface. (Problem to be Solved by the Invention) However, in the above-mentioned clear type, the light incident on the optical fiber a at an angle greater than the aperture angle undergoes total internal reflection at the interface with the optical fiber cladding b. without causing the optical fiber clad b
passes through and enters the adjacent optical fiber a,
The light reaches the light exit surface d. Similarly, the light that first enters the optical fiber clad b passes through the optical fiber clad b and reaches the light exit surface d of the optical fiber a. Such leakage light has been a factor in deteriorating image quality when transmitting images using an optical fiber array. On the other hand, in the above-mentioned EMA type optical fiber array, although the leaked light is absorbed by the absorber c and there is almost no stray light, there is a problem that the surface of the document to be read cannot be irradiated with this. The present invention has been made in view of the above circumstances, 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) The contact image sensor of the present invention includes 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 connection between the light receiving element and the document. A contact image sensor comprising: a substrate incorporating an optical fiber array disposed between the substrate; and an absorber for preventing light leakage interposed between each optical fiber of the optical fiber array; , the optical fiber array is disposed at an arbitrary position excluding a predetermined length from at least the end of the optical fiber array facing the original. (Function) An absorber for preventing light leakage is interposed between each optical fiber of the optical fiber array at any position excluding a predetermined length from at least the end facing the original of the optical fiber array, By adopting a structure in which no absorber is inserted between the optical fibers near the original, the surface of the original to be read can be illuminated by the light source, and leaked light can be prevented from entering the light receiving element. It is absorbed by the absorber just before it is absorbed. (Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows a front view of the contact type image sensor of the present invention, and FIG. 2 shows an enlarged view of the optical fiber array portion. In the figure, 1 is a document, 2 is an LED array light source, 3 is an optical fiber array in which a large number of optical fibers 3a, 3a... are focused into a band shape, and a cladding portion 4 (second (see figure) are interposed with absorbers 5, 5, . . . for preventing light leakage. The absorbers 5, 5... are of a hybrid type and are placed at any position between the optical fibers 3a, 3a..., at least at a predetermined length 1 removed from the end 3c of the optical fiber array facing the original. It is possible to irradiate the document 1 with light from the LED array light source 2. That is, the predetermined length l is a length that allows light from the LED array light source 2 to enter the document surface. In the illustrated example, the absorbers 5, 5, . . . are arranged from the middle between the optical fibers 3a, 3a, . In short, as long as it has a length that can reliably block leakage light, it may be placed at any position other than the portion of the predetermined length l. Further, 6 is an insulating substrate incorporating this optical fiber array 3, 7 is a wiring electrode formed on the upper surface of this substrate 6, and 8 is arranged opposite to the light output surface 3b of the optical fiber array 3. A light receiving element 9 is a wiring electrode 1 formed on the light receiving surface 8a side of the wiring electrode 7 and the light receiving element 8.
0 (see FIG. 3). In addition, the light receiving element 8, as shown in FIG.
They are arranged in a horizontal row in the longitudinal direction of the substrate 6 so as to have approximately the same length as the width of the document 1. Next, a procedure for manufacturing the contact type image sensor having the above configuration will be explained. In this example, a CCD sensor having a structure shown in FIGS. 3a and 3b and having a resolution of 8 lines/mm and having a length of about 70 mm is used as the light receiving element 8. That is,
On the light receiving surface 8a, in order to prevent a decrease in resolution at the joint portion of the light receiving element 8, a light receiving section 11a and a transfer section 11b are formed up to the vicinity of the CCD end, and extraction electrode sections (wiring electrodes) are formed on both sides of the width direction. ) 10 is formed as many times as necessary. Then, on the light receiving surface 8a of the light receiving element 8 including the light receiving part 11a and the transfer part 11b, a passivation film 12 (see b in the same figure) made of S _ix N _{1-x Si} O ₂ etc. is formed using thin film technology. death,
Furthermore, solder bumps 9 are formed on the lead electrode section 10. On the other hand, as the optical fiber 3a, a quartz-based or multicomponent-based glass fiber is used. A large number of optical fibers 3a are converged into a strip to form an optical fiber array 3, and a substrate 6 is formed by sandwiching the optical fiber array 3 from both sides (see FIG. 4). Then, on the upper surface of this substrate 6, a lead electrode part 7a, which is the wiring electrode 7, and a connection electrode part 7b, which connects to the solder bump 9, are formed as thin films using microfabrication technology. The light receiving portion 11a of the light receiving element 8 thus formed is connected to the light emitting surface 3b of the optical fiber 3a.
The extraction electrode portion 10 on the light receiving element 8 side and the connecting electrode portion 7b on the substrate 6 side are connected by reflow bonding. The reflow bonding method is performed by heating the solder bumps 9 in a belt furnace at 180° C. to 350° C. to melt them. In this way, the connection between the light receiving element 8 and the substrate 6 is performed both for fixing the position of the light receiving element 8 and for electrical connection. Note that according to this manufacturing method, alignment can be performed using the solder bumps 9, and the elongated light receiving element 8 can be aligned with high productivity due to the self-alignment effect of the solder. In addition, since the optical fiber array 3 is used instead of an optical lens, the optical path length can be freely selected, the entire sensor can be made smaller, and there is no need to adjust the focus of the lens as in the conventional case. Lower prices can also be achieved. moreover,
Since the distance between the light-receiving surface 8a of the light-receiving element 8 and the light-emitting surface 3b of the optical fiber 3 can be set extremely short, the document can be read with high resolution. Furthermore, since the light-receiving element 8 and the substrate 6 incorporating the optical fiber array 3 can be manufactured separately, a high yield can be achieved. In this way, in the contact type image sensor (hereinafter referred to as hybrid type) of the present invention, as in the EMA type, light leakage is completely prevented by the absorber 5 interposed at a predetermined position between each optical fiber 3a. absorbed into
There is almost no stray light (see Figure 2). Figure 5 shows the resolution (MTF) characteristics of optical fiber arrays with various structures. From the same figure, in the clear type shown in Figure 6a, the MTF characteristics are degraded due to light leakage.
It can be seen that the hybrid type according to the present invention has almost the same MTF characteristics as the EMA type shown in FIG. 6b. However, the light receiving surface 8a of the light receiving element 8 and the light emitting surface 3 of the optical fiber array 3
If the distance to b is more than twice the required resolution pitch, the MTF characteristics will deteriorate, so the light receiving surface 8
The distance between a and the light exit surface 3b needs to be less than twice the resolution pitch. The table below shows the performance comparison results for different types of optical fiber arrays.

[Table] In the above example, 8/8 light receiving elements are used.
Although a CCD sensor chip with a resolution of mm and a length of approximately 70 mm is used, it is obvious that other IC sensors or thin film sensors can also be applied. (Effects of the Invention) As explained above, according to the contact type image sensor of the present invention, any position between each optical fiber that is removed by a predetermined length from at least the end facing the original of the optical fiber array Since the absorber is interposed in the light, it is possible to irradiate the document surface, and also to reliably cut out leakage light and maintain good resolution characteristics.

[Brief explanation of the drawing]

FIG. 1 is a front view of the contact type image sensor of the present invention, FIG. 2 is a partially enlarged view of the optical fiber array shown in FIG. 1, and FIGS. , Figure 4 is a partial plan view of the contact type image sensor shown in Figure 1, Figure 5 is a curve diagram showing the MTF characteristics of various optical fiber arrays, and Figure 6 is a partial plan view of the contact type image sensor shown in Figure 1.
Figures a and b are partially enlarged front views of the optical fiber array portion of a conventional contact type image sensor. DESCRIPTION OF SYMBOLS 1... Original, 2... LED array light source, 3... Optical fiber array, 3a... Optical fiber, 4... Clad part, 5... Absorber, 6... Substrate, 7... Wiring electrode, 8
...Light receiving element, 9...Solder bump, 10...Leader electrode part.

Claims (1)

[Claims] 1. A light source that illuminates the original to be read, a light receiving element that converts reflected light from the original into an electrical signal, and an optical fiber array disposed between the light receiving element and the original. In a contact image sensor comprising a substrate and an absorber for preventing light leakage interposed between each optical fiber of the optical fiber array, the absorber is arranged at least at an end of the optical fiber array facing the original. 1. A close-contact image sensor, characterized in that the image sensor is disposed at an arbitrary position excluding a predetermined length from the area.