JPS60244152A - Transparent original reading device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Technical field of invention) The present invention relates to a transparent original reading device.

(Background of the Invention) Conventional document reading devices such as facsimiles and copying machines are
An illumination beam from a light source is irradiated onto the surface of a document on which an image is placed, and reflected light corresponding to the document image is received by an image sensor, a photosensitive drum, or the like. In this method, the light emitted from the light source cannot be efficiently used as a light beam for reading an original unless a light beam convergence system is used. In other words, in order to perform good document reading, a high-intensity light source and an expensive converging optical system are required, which leaves problems with chromatic aberration and focus adjustment.

Even with a document reading device that uses a contact-type image sensor that does not use a converging optical system, it is difficult to effectively guide the illumination light flux to the document surface and also effectively guide the reflected light from there to the image sensor surface. After all, it is not easy to improve the signal-to-noise ratio, signal strength, and reading speed.

Therefore, the present inventor first invented a transmissive document reading device that consists of a light source that illuminates the document from behind and an image sensor that receives the light emitted from the light source and passes through the document and converts it into an electrical signal. and filed a patent application.

(Object of the Invention) An object of the present invention is to improve the previously invented transmissive original reading device and to obtain a device equipped with an illumination light source with high illumination efficiency.

(Summary of the Invention) Therefore, the present invention provides a transmissive image sensor that includes a linear light source that illuminates a document from behind and a linear image sensor that receives light emitted from the light source and passes through the document and converts it into an electrical signal. In the type document reading device, the linear light source includes a cylindrical reflector, a slit-shaped fenestration provided in the longitudinal direction of the reflector, and a light emitting portion provided inside the reflector. A transparent original reading device is provided.

The present invention will be explained below with reference to Examples.

(Embodiment) FIG. 1 is a schematic cross-sectional view of a document reading device of this embodiment. The linear contact type image sensor (1) is connected to the original (2)
feeding direction (called the sub-scanning direction and represented by an arrow)
width D (10 μm to 300 μm) in the direction perpendicular to
It has a light receiving section.

The image sensor (1) is fixed to the base material (5) with a mounting plate. A document (2) is sent between a transparent press plate (4) and an image sensor (1) by a feed roller (3), and receives a light beam from a linear light source (6). The light flux that has passed through the original (2) is received by the image sensor (1), converted into an electrical signal, and transmitted to the outside.

FIG. 2 is a cross-sectional view of a fluorescent tube as an example of a linear light source (1), in which a reflector (8) and a fluorescent layer (9) are laminated on the inner surface of the glass tube (7). has been done. A slit-like fenestration (8a) is provided as a light extraction port, and the reflector (8) and fluorescent layer (9) are removed from this fenestration (8a). And there is mercury vapor inside.

A light emitting source aQ is enclosed.

According to this structure, compared to a normal fluorescent tube with the same power consumption, a high-intensity light source can be obtained and one fenestration (8a
) can effectively reach the image sensor (1)K. Glass tube (7) near the fenestration (8a)
The thickness accuracy, curvature accuracy, and glass uniformity accuracy have almost no effect on the reading of the document even if no special attention is paid.

Another embodiment is shown in FIG. (1), (2), (
5) and (6) are the same members as in Example 1. Manuscript (2
) is sent along the document rail Qυ into the gap between the transparent rotating document feed roller (2) and the contact image sensor (1), and is moved by the friction of the document feed roller (2). Since this roller (6) is made of a transparent resin or a glass tube coated with a transparent resin, the roller (6) transmits the light beam from the light source (6) and does not become an obstacle when the entire document (2) is illuminated.

Furthermore, if the surface of this roller (2) is made elastic, it will be able to properly feed documents (2) of different thicknesses. The rotating document feed roller (2) includes a support roller (2), a4. (g), and obtains rotational force by transmitting the rotational motive force from one of the supporting rollers. This situation is shown in FIG.

The light source (6) is fixed to the external wiring body A, and the transparent rotating roller (B) is connected to three supporting rollers (G), H,
(It rotates while being supported by (1→. (8a) is a document, and (8a) is a slit-like fenestration. When the roller (B) and light source (6) with this structure are used, it is possible to bring the document (2) into close contact with a contact-type image sensor (not shown). A transparent press plate is no longer required.

Further, the transparent rotating roller (2) may be narrower than the document width.

Example 3 is shown in FIG. (1) to (5) are the same members as in Fig. 1, and the light emitted from the ordinary fluorescent tube ◇η is
The light is reflected within the cylindrical reflector α frame whose inner wall is a reflecting mirror, and exits from the slit-like fenestration (18a). This reflector θ camphor is a glass tube or plastic tube whose inside or outside is coated with a highly reflective material by vapor deposition, sputtering, spraying, or the like. Alternatively, the inner surface of the metal tube may be mirror-finished. These reflectors are provided with slit-like fenestrations (2) so that light can be taken out. If this structure is used, a high-intensity light source can be easily obtained using an ordinary white fluorescent lamp as a light source.

(Effects of the Invention) As described above, according to the present invention, a high-intensity light source can be obtained, and as a result, the SN ratio 1 resolution, signal strength, and reading speed of the document reading device are improved.

In addition, Example 1 does not require an expensive optical system,
The light beam can be concentrated on the document, which is advantageous in terms of illumination efficiency for bulky and high-speed reading. Further, even if the thickness of the document is 200 μm or more, a signal with a high signal-to-noise ratio can be obtained.

In the second embodiment, since the volume occupied by the document feed roller can be reduced, it is possible to make the document feeder even more L-shaped. Also,
Good adhesion between the image sensor and the document can be maintained without using a transparent press plate. .

Therefore, abrasion of the transparent pressing plate with the original can be avoided.

In the third embodiment, a high-intensity light source can be obtained even if a normal full-surface fluorescent tube is used, so that an inexpensive and easily miniaturized document reading device can be manufactured.

Furthermore, since the structure prevents dust and dirt from entering the reflector tube from the outside, the illumination stability is excellent, and almost no maintenance is required even after long-term use.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a document reading device according to a first embodiment of the present invention. FIG. 2 is a sectional view of the linear light source used in Example 1. FIG. 3 is a schematic cross-sectional view of the same document reading device according to the second embodiment. FIG. 4 is a perspective explanatory view of the same device according to the second embodiment.
7. FIG. 5 is a schematic cross-sectional view of the same document reading device according to the third embodiment. [Explanation of the symbols of the upper narrow part] 1 ・・・・・・・・・・・・・・・・・・ Line image sensor 2 ・・・・・・・・・・・・・・・・・・・Manuscript 6・・・・・・・・・・・・・・・・・・Applicant for linear light source Takashi Watanabe Agent for Nippon Kogaku Kogyo Co., Ltd. Male Mj diagram Figure 2 1α Figure 4 Figure 4 Figure 5

Claims (1)

[Claims] In a transmission type document reading device, which includes a linear light source that illuminates the document from behind and a linear image sensor that receives light emitted from the light source and passes through the document, and converts it into an electrical signal, A transmission-type original reading device characterized in that the light source comprises a cylindrical reflector, a slit-shaped aperture provided in the longitudinal direction of the reflector, and a light emitting source provided inside the reflector. .