JPH01205104A - Contact-type image sensor - Google Patents

Abstract

PURPOSE:To give an excellent MTF characteristic to a contact-type image sensor by forming a light guiding film in such a state that the film is integrated with part of an optical fiber plate to one body. CONSTITUTION:The light emitted from a light source 1 is projected on the surface of a light guiding film 6 after passing through a light transmissive base plate 2b constituting an optical fiber plate 2 and is further projected on an original 4 after the light is led to the end section 6a of the film 6. The light projected on the surface of the original is reflected and scattered and optical information is given to the light receiving surface of a photoreceptor element 51 through an optical fiber 2a. When the film 6 is formed on the surface of the optical fiber plate 2, light projection on the surface of the original 4 becomes possible even if the optical fiber plate 2 contains a light absorbing body 3. Therefore, a contact-type image sensor having an excellent MTF characteristic can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a contact type image sensor suitably used in facsimile machines, two-image character reading/input devices, and the like.

<Prior Art> In recent years, development of input devices for reading and inputting characters, images, etc. using a contact type image sensor has been active in order to contribute to miniaturization and cost reduction of the devices. However, in most of the above-mentioned contact image sensors, the optical information from the document is usually imaged on the light receiving surface of the sensor through the rod lens array, so the document and the sensor must be separated by the conjugate length of the rod lens array. As a unit of a contact type image sensor, the thickness is 20 m+ to 30 m+, which naturally limits miniaturization. Furthermore, since a lens system is used, optical adjustment is required, and there is also the problem that the light transmission rate decreases.

Therefore, in order to solve the above-mentioned problems, a method has been proposed that does not use a rod lens array but instead uses an optical fiber plate in which a plurality of original fibers are assembled in an array in a substrate.

The original fiber plate is one in which the light-receiving surface of the sensor is placed on one end of the optical fiber, and the surface of the document to be read is placed in close contact with or in close proximity to the other end, so that photogenic information from the document is guided through the optical fiber to the light-receiving surface of the sensor. Since no system is used, no optical adjustment is required, and the light transmission rate is sufficiently high, and by shortening the length of the optical fiber, an ultra-small contact type image sensor unit can be created.

An example of the structure of a contact type image sensor using the above-mentioned original fiber plate is shown in FIG. In this Figure 4, I is a light source, and this light source! The light emitted from
The original 4 is passed diagonally across the optical fiber plate 2.
is irradiated. The reflected light from the original 4 is transmitted to the original fiber 2.
The light is guided to the light receiving element 5 through a.

Further, a specific example of the structure of the optical fiber plate 2 described above is shown in FIGS. It has a structure in which it is sandwiched in place, glued, or bonded by heat fusion. In the optical fiber plate shown in FIG. 2(a), among the light incident on the optical fiber 2a, the light incident at an angle equal to or greater than the aperture angle of the optical fiber is
If the total internal reflection condition is not satisfied, the light passing through the optical fiber will enter the adjacent optical fiber. On the other hand, the same figure (b
) has the absorber 3 between each fiber for absorbing the leaked light as described above, so that it is possible to reduce the amount of light entering adjacent optical fibers. FIG. 6 shows the MTF characteristics of the optical fiber plates shown in FIGS. 5(a) and 5(b).

As is clear from FIG. 6, the optical fiber rate shown in FIG. 5(b) with extremely low leakage light is
It can be seen that this is much superior to the optical fiber plate shown in a).

<Problems to be Solved by the Invention> However, when considering the structure of a contact type image sensor as shown in FIG. In 2,
Since the light from the light source 1 is absorbed by the absorber 3, a problem arises in that the document 4 cannot be irradiated.

The present invention was devised in view of the above problems, and the MTF
The purpose of the present invention is to provide an ultra-compact contact image sensor that enables irradiation of a document 4 even with an optical fiber plate 2 interposed with an absorber 3 having excellent characteristics, and that also has good productivity. It is said that

Means for Solving the Problems In order to achieve the above object, the contact image sensor of the present invention includes a light source, a light guide film that guides light from the light source to the document surface, and a light guide film that guides light from the document surface. It consists of a light-receiving element that converts light into an electrical signal and an optical fiber plate that guides the reflected light from the original to the light-receiving element.The light guiding film mentioned above is formed integrally with a part of the optical fiber plate. It is configured so that

Further, in a preferred embodiment of the present invention, the light-guiding film is made of a resin film containing phosphor.

As described above, in the present invention, in order to irradiate the document surface with light from a light source through a light-guiding film, an optical fiber rate that can obtain good MTF characteristics is achieved by interposing an absorber between each optical fiber. Since a part of the optical fiber plate and the light-guiding film can be integrally formed, it is possible to provide a contact-type image sensor with good productivity.

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

FIG. 1 shows a cross-sectional view of the structure of the contact type image sensor in this embodiment.

In the figure, l is a light source, 2 is an optical fiber plate consisting of an optical fiber 2a and a transparent insulating substrate 2b, 3 is an absorber, 4 is an original, 51 is a CCD linear sensor as a light receiving element, and 6 is a light guiding film. , 13 are wiring electrodes, and the light emitted by the light source 1 passes through the transparent substrate 2b constituting the optical fiber plate 2 and illuminates the surface of the light guiding film 6. The light that has irradiated the surface of the light guiding film 6 is guided to the end portion 6a of the light guiding film and illuminates the original 4. Manuscript 1
The light irradiated to ff14 is reflected and scattered, and is connected to optical fiber 2.
Optical information is given to the light-receiving surface of the light-receiving element 5 through a. The optical fiber plate 2 is adapted to have an absorber 3 interposed between each optical fiber 2a to absorb the source of leakage, as shown in FIG. 5(b).

Next, the light guiding film 6 will be explained in detail.

The light guide film 6 is made of a resin film containing a suitable fluorescent material. The principle of the light guide film 6 is that when the light guide film surface is irradiated with light, the phosphor dispersed in the light guide film emits light, and the light emitted from the phosphor is transmitted throughout the light guide film. If the reflection condition is not satisfied, the light is guided to the end of the light guiding film and is emitted from the end 6a of the light guiding film.

Next, a method for manufacturing the contact type image sensor according to the embodiment of the present invention described above will be explained.

First, quartz-based or multicomponent-based original fiber 2a is
The optical fiber plate 2 is formed by bundling each book covered with the absorber 3 into a play shape, inserting the sheets between transparent substrates 2b from both sides, and heat-sealing them. A resin film containing phosphor, which will become the light-guiding film 6, is applied to a thickness of several tens of microns on the surface of the original fiber plate 2 obtained in this way, which faces the original surface 4, and then becomes the original irradiated area. By removing the light guiding film at the position, the light emitting end surface 6a is obtained. Light output end face 6
A is shaped to have an appropriate angle so that the original 4 can be easily irradiated. In this embodiment, polycarbonate or acrylic resin in which a green luminescent material is dispersed is used as the light guiding film. Note that the reason why a phosphor that emits green light is used is to enable faithful reading even of originals containing red, which is commonly used.

Next, a light receiving element is provided on the surface of the optical fiber plate opposite to the surface on which the light guiding film 6 is applied. In this embodiment, a CCD linear sensor 51 was used as a light receiving element.

FIG. 2(a) is a schematic plan view of the CCD sensor used in this example, and FIG. 2(b) is a sectional view taken along line A-A' in FIG. 2(a). In FIGS. 2(a) and (b), 7 is a silicon substrate, 8 is a light receiving section, 9 is a transfer section, IO is an electrode terminal section,
11 is a solder bump formed on the electrode terminal portion, and 12 is a protective film. Furthermore, in IC sensors such as CCD sensors,
The reading width is limited by the size of the Si wafer, so when a long reading width is required, such as in a contact image sensor, multiple sensor chips are connected in a straight line in one row. I am trying to get the necessary light receiving area.

The CCD sensor in this example has a resolution of approximately 7211 lines/m.
It has 111 light receiving sections, and three sensor chips are joined together to create an A4 size sensor.

Furthermore, in order to prevent deterioration of resolution at the seam, the light receiving section is formed as close to the end of the COD as possible.

Figure 3 shows a CCD sensor 51 on the optical fiber plate 2.
This figure shows how the fiber plates are arranged in one row, and the wiring electrodes 13 for relaying from the electrode terminal part 10 of the CCD sensor 51 (see Fig. 2) to the control circuit are previously formed on the two sides of the original fiber plate. are doing. Next, the light receiving surface of the CCD sensor 51 and the light emitting surface of the optical fiber 2a are arranged so as to face each other, and the terminal of the CCD sensor and the wiring electrode 13 on the original fiber plate side are connected by the reflow bonding method. The reflow bonding method uses 18
This is done by heating at 0° C. to 350° C. to melt the solder bumps 11 (see FIG. 2). In this way, the connection between the CCD sensor 51 and the optical fiber plate 2 is performed both for fixing the position of the CCD sensor 51 and for electrical connection. According to this manufacturing method, alignment using solder bumps is possible, and the elongated light receiving element can be aligned with high productivity due to the self-alignment effect of the solder.

The contact image sensor as an embodiment of the present invention manufactured as described above has a light-guiding film formed on the surface of the optical fiber plate, so that even when using the optical fiber plate with an absorber interposed, Since light irradiation of M is possible, M
A contact type image sensor with good TF characteristics could be obtained.

In addition, although the above embodiment describes the case where a CCD sensor is used as a light receiving element, the present invention is not limited to the type of light receiving element, and may be applied to other IC sensors or thin film sensors such as a-8i. Needless to say, it can be applied even if

<Effects of the Invention> As explained above, the contact image sensor of the present invention uses an optical fiber plate without using an optical lens, so the optical path length can be freely selected, and the entire sensor can be miniaturized. At the same time, since there is no need to adjust the focus of the lens as in the conventional case, the cost can be reduced. Furthermore, since the document surface is irradiated using a light-guiding film, it is possible to use an optical fiber rate in which an absorber is interposed between each optical fiber, and as a result, a contact type image sensor with excellent MTF characteristics can be obtained. Furthermore, since the light-guiding film can be formed directly on the surface of the optical fiber plate, productivity is also excellent.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a cross section of a contact type image sensor as an embodiment of the present invention, and FIGS. 2(a) and (b) are CCs used as light receiving elements in the embodiment of the present invention.
A plan view and a vertical cross-sectional view of the D linear sensor, FIG. 3 is a plan view showing a state in which CCD sensors are arranged on an optical fiber plate, and FIG. 4 is a schematic diagram of a conventional contact type image sensor using an optical fiber plate. 5(a) is a configuration diagram of an optical fiber plate without an absorber, FIG. 5(b) is a configuration diagram of the original fiber plate with an absorber interposed between each optical fiber, and FIG. FIG. 5 is a characteristic diagram showing the MTF characteristics of the optical fiber plate shown in FIGS. 5(a) and 5(b). l...Light source, 2...Optical fiber, -plate (2a
: Optical fiber, 2b: Transparent insulating substrate), 3... Absorber, 4... Original, 5... Light receiving element, 51... C
CD IJ near sensor, 6...light guide film, 7...S
i Ueno 1.8... Light receiving section, 9... Transfer section, 10.
... Electrode terminal portion, 11... Solder bump, 12... Protective film, 13... Wiring electrode. Agent Patent Attorney Takeshi Sugiyama (and 1 other person) Figure I (CI) Figure 2 Figure 4

Claims (1)

[Claims] 1. A light source, a light guide film that guides light from the light source to the surface of 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. and an optical fiber plate in which a plurality of optical fibers that guide light to the light receiving element are incorporated into a substrate, and the light guiding film is formed integrally with a part of the optical fiber plate. sensor.