JPH05344280A - Light source for contact-type image sensor - Google Patents

Abstract

PURPOSE:To thin and miniaturize a light source by providing distributed EL where the side of a transparent substrate is set to be a light-emitting surface so that it follows one side of a light transmission window provided at a part of the transparent substrate. CONSTITUTION:The light source 1 is composed of distributed EL 30 which is brought into contact with a back surface 2a where the light transmission window 3 is formed at the transparent substrate 2 and in which the side of the back surface 2a is set to be the light-emitting surface. When distributed EL 30 is lighted, the light passes through the transparent substrate 2, irradiates an original 20 which is closely adhered to a front surface 2b, is reflected on the surface of the original 20, passes through the transparent substrate 2 again, reaches the contact-type image sensor 10 through the light transmission window 3 and reading is executed. Here, the thickness of whole distributed EL 30 composed of a transparent electrode 4, a light-emitting layer 5, an insulating layer 6 and a back electrode 7 is 100-200mum. Even when the board thickness of 1mm is used as the transparent substrate 2 and the sensor substrate 11, for example, a whole reader by the light source 1 and the contact-type image sensor 10 can be set to about 2mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device such as an image scanner or a facsimile, and more particularly to a light source for illuminating a document in the reading device.

[0002]

2. Description of the Related Art FIGS. 8 and 9 show examples of a light source used in a conventional reader of this type. First, FIG.
In the structure shown in FIG. 1, a tubular light source such as a fluorescent lamp or a halogen lamp is adopted as the light source 90.
The lens 92 is used to form an image on the image sensor 93 in the range in which 1 is uniformly irradiated.

The light source 80 shown in FIG. 9 is composed of a plurality of LEDs.
Are arrayed in an array, and optical means such as mounting a lens on each LED so that the combined irradiation light from the respective LEDs has a uniform illuminance on the surface of the original 81, The distance from the original 81 is also optimized and the light source 80 is usually combined with a rod lens 82 and a contact image sensor 83.
It is said that the size can be reduced as compared with that shown in FIG.

[0004]

However, in the above-described conventional light source 90, since the light source 90 itself is large, it naturally causes a limit when it is downsized and thinned. There is a problem that it is impossible to cope with the case where thinning is required, and in the light source 80 as well, in order to obtain a uniform illuminance, a certain gap (specifically, between the light source 80 and the document). 20 mm) is required, and further miniaturization and thinning are impossible, and in addition, since the individual LEDs of the light source 80 have variations in luminance, it is necessary to correct the luminance of each LED. In addition, there is a problem in that it takes time and effort to manufacture and causes a cost increase.

[0005]

The present invention is, as a concrete means for solving the above-mentioned conventional problems, a close contact which is provided in a part of the transparent substrate so as to be substantially in close contact with the back surface of the transparent substrate. A rectangular window-shaped light transmission window arranged in a slit shape or a line shape is formed corresponding to the image sensor, and the light emitting surface is formed on the back surface of the transparent substrate with the light emitting surface facing the transparent substrate side and an opaque back electrode for a light emitting layer The contact-type image sensor is characterized in that a dispersion-type EL configured to cover the contact-type image sensor so as not to emit direct light to the contact-type image sensor is provided along at least one side of the light-transmitting window. It is intended to solve the above-mentioned conventional problems by providing a light source for use, which enables further reduction in size and thickness.

[0006]

EXAMPLES The present invention will now be described in detail with reference to the examples shown in the drawings. A reference numeral 1 in FIG. 1 is a first embodiment of a light source for a contact type image sensor (hereinafter abbreviated as light source 1) according to the present invention. The light source 1 is formed on a transparent substrate 2 made of glass or the like. The transparent substrate 2
As shown in FIG. 2, the rear surface 2a of the light transmitting window 3 has a shape corresponding to the contact type image sensor 10 described later.
Are framed by a frame portion 3a formed by a photographic means such as photolithography etching using a resist in which a black paint is dispersed. In the first embodiment, the frame portion 3a is formed.
a is formed as an insulator.

Referring again to FIG. 1, on the transparent substrate 2 having the light transmitting window 3 formed as described above, ITO is formed on both sides of the light transmitting window 3 in this embodiment by means such as vacuum deposition or sputtering. A transparent electrode 4 referred to as "a transparent electrode 4" is formed in a state where the transparent electrode 4 is in contact with the light transmitting window 3 at its end (see also FIG. 1). Further, the transparent electrode 4 has ZnS in an organic binder. A light emitting layer 5 in which a phosphor such as is dispersed is formed and laminated by, for example, screen printing means.

Further, an insulating layer 6 in which powder of a high dielectric material such as BaTiO ₃ is dispersed in an organic binder is formed on the light emitting layer 5 by the same screen printing means as that for forming the light emitting layer 5. At this time, the insulating layer 6 is formed so as to wrap around the end face of the light emitting layer 5 at the end portion on the light transmitting window 3 side and reach the frame portion 3a.

In addition, an opaque back electrode 7 is formed on the insulating layer 6 by screen printing means of Ag paste or vacuum evaporation of Al, and the back electrode 7 is also at the end portion on the light transmitting window 3 side. Therefore, the light emitted from the light emitting layer 5 does not leak to the light transmitting window 3 side.

According to the above procedure, the light source 1 of the present invention in which the dispersion type EL 30 is arranged on both sides of the light transmitting window 3 is formed, and thereafter, the contact type image sensor 10 in which a plurality of light receiving elements are arranged in a line. Sensor board 11 on which is mounted
However, the contact type image sensor 10 side is made to face the light transmitting window 3 and is adhered onto the back electrode 7 with an adhesive 12, for example.

At this time, each of the light transmitting windows 3 is formed so as to correspond in position to each of the light receiving elements of the contact type image sensor 10, and therefore, each of the light receiving elements is dedicated to itself. It is sensitive to the light and darkness of the transmitted light from the facing light transmitting window 3, and specifically, the lightness and darkness of the surface of the original 20 which is in close contact with the front surface 2b of the transparent substrate 2 is determined.

Next, the light source 1 of the present invention having the above structure
The operation and effects of the light source 1 will be described. The light source 1 is close to the same surface as the back surface 2a on which the light transmitting window 3 is formed on the transparent substrate 2, and the light emitting surface is on the back surface 2a side.
30 is arranged, and when this dispersion type EL 30 is turned on, its light emission is transmitted through the transparent substrate 2,
The original 20 which is in close contact with the other front surface 2b is illuminated, and this illumination light is reflected by the surface of the original 20 and transmitted through the transparent substrate 2 again, and comes into close contact through the light transmission window 3. It reaches the mold image sensor 10 and is read.

At this time, since the frame portion 3a is black, for example, stray light or the like generated by the internal reflection inside the transparent substrate 2 is absorbed by the frame portion 3a and the contact image sensor 10 is obtained. Is prevented, and the quality of the obtained data is improved, such as the contrast of the read image is improved.

Since the total thickness of the dispersion type EL 30 composed of the transparent electrode 4, the light emitting layer 5, the insulating layer 6 and the back electrode 7 is 100 to 200 μm at most, the transparent substrate 2 and the sensor substrate 11 are used as plates. Even when the thickness of 1 mm is adopted, the entire reading device including the light source 1 and the contact image sensor 10 can be realized as an extremely thin one of about 2 mm or more in the present invention.

FIG. 3 also shows a second embodiment of the present invention, which is different from the first embodiment in which the light emitting layer 5 is directly laminated on the transparent electrode 4. In the example, after the light transmission window 3 and the transparent electrode 4 are formed, a transparent insulating layer 8 formed by vapor deposition or sputtering of, for example, SiO ₂ is formed so as to cover both of them 3 and 4. After that, the light emitting layer 5 is formed in the same manner as in the first embodiment, and thereafter, the back electrode 7 is directly formed on the light emitting layer 5.

That is, since the insulating layer 6 is opaque in the first embodiment and is disposed on the back side of the light emitting surface of the light emitting layer 5, the insulating layer 6 is provided as a transparent transparent insulating layer 8 on the light emitting surface side of the light emitting layer 5. By doing so, since both the light transmitting window 3 and the transparent electrode 4 are covered with the transparent insulating layer 8, the insulation between the transparent electrode 4 and the back electrode 7 is maintained. However, it can be performed without providing the means for wrapping the insulating layer 6 around the end face of the light emitting layer 5 described in the first embodiment, and the production process can be simplified.

Further, when the frame portion 3a and the transparent electrode 4 are laid with an appropriate gap provided therebetween, the frame portion 3a and the transparent electrode 4 are covered with the transparent insulating layer 8, so that
Since the back electrode 7 provided thereafter is also insulated, the frame 3a can also be formed as a conductive film surface such as a metal film, and can be formed by a simpler production means such as vapor deposition by masking. . The operations and effects other than the above are the same as those of the first embodiment, and thus detailed description thereof will be omitted here.

In the actual implementation of the present invention, the dispersion type EL 30 may be provided only on one side of the light transmitting window 3, that is, the frame portion 3a as shown in FIG. 4 as the third embodiment, or For example, when each of the light receiving elements of the contact image sensor 10 is provided with an optical means such as a lens and has an appropriate light receiving angle characteristic, the frame portion 3a is omitted as shown as the fourth embodiment in FIG. The light transmitting window 3 may be formed in a slit shape sandwiched by the dispersion type EL 30 from both sides.

Furthermore, in carrying out the present invention, the shape of the dispersion type EL 30 is not limited, and the dispersion type EL 30 is formed in a frame shape as shown as a fifth embodiment in FIG. 6, for example. The dispersion type EL 30 may be used to form the light transmission window 3, or, as shown as a sixth embodiment in FIG. 7, the slit-shaped transparent portion formed by the frame portion 3a may be traversed at a constant pitch. It is also possible to dispose the dispersion type EL 30 and form the light transmission window 3 by the frame portion 3 a and the dispersion type EL 30.

[0020]

As described above, according to the present invention, a dispersion type EL device having a light emitting surface on the transparent substrate side along at least one side of a light transmission window provided on a part of the transparent substrate.
Since the light source for the contact image sensor is provided with the light source for the contact image sensor, the light source for the contact image sensor has substantially the same thickness as that of the transparent substrate, and the light transmission window and the dispersion EL are extremely small. Since they are provided close to each other, it is possible to illuminate a necessary portion in a state where the original is brought into close contact with the front side of the transparent substrate, and between the original and the light source and the contact type image sensor required in the conventional light source of this type Any of these intervals can be drastically shortened, and this type is extremely effective in reducing the thickness and size of an image reading device.

Further, by forming the light transmission window by the frame portion using the resist in which the black pigment is dispersed, even if the light transmission window and the dispersion type EL are extremely close to each other as described above, In addition to blocking the direct light, it also absorbs stray light and the like due to internal reflection in the transparent substrate, and has the effect of improving the data quality such as improving the contrast.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a light source for a contact image sensor according to the present invention.

FIG. 2 is a perspective view showing a main part of the same embodiment.

FIG. 3 is a sectional view showing a second embodiment of the light source for the contact type image sensor according to the present invention.

FIG. 4 is a front view showing a third embodiment of the light source for the contact type image sensor according to the present invention as well.

FIG. 5 is a front view showing a fourth embodiment of the light source for the contact type image sensor according to the present invention as well.

FIG. 6 is a front view showing a fifth embodiment of the light source for the contact type image sensor according to the present invention as well.

FIG. 7 is a front view showing a sixth embodiment of the contact type image sensor light source according to the present invention as well.

FIG. 8 is a perspective view showing a conventional example.

FIG. 9 is a perspective view showing another conventional example.

[Explanation of symbols]

 1 ... Light source for contact type image sensor 2 ... Transparent substrate 2a ... Rear surface 2b ... Front surface 3 ... Light transmission window 3a ... Frame part 4 ... Transparent electrode 5 ... Light emitting layer 6, 8 ... Insulation Layer 7 ... Back electrode 10 ... Contact image sensor 11 ... Sensor substrate 20 ... Document 30 ... Dispersion EL

Front page continuation (72) Kenichi Kondo 2-33-1, Chitosedai, Setagaya-ku, Tokyo (72) Inventor Shinichiro Seki 5-10-8 Tamagawa Gakuen, Machida City, Tokyo (72) Inventor Tatsuya Goto Yokohama, Kanagawa Prefecture 713 Terayama-cho, Midori-ku, Yokohama

Claims (2)

[Claims] 1. Light transmission in the form of a rectangular window arranged in a slit shape or in a line shape corresponding to a contact type image sensor arranged in a part of the transparent substrate so as to be substantially in contact with the back surface of the transparent substrate. A window is formed, and the light emitting surface is on the back surface of the transparent substrate, and the light emitting layer is covered with an opaque back electrode so that direct light is not emitted to the contact image sensor. A light source for a contact type image sensor, wherein a dispersion type EL is provided along at least one side of the light transmission window. 2. The light source for a contact image sensor according to claim 1, wherein the light transmitting window is formed by a frame portion using a resist in which a black pigment is dispersed.