JPS60244151A - Original reader - Google Patents

Abstract

PURPOSE:To increase the resolution and the signal intensity of an original reader and also to attain miniaturization of the reader, by illuminating an original through its back by a light source and converting the light transmitted through the original into electric signals by an image sensor. CONSTITUTION:A light source 10 illuminates the back of an original 8 moving toward an arrow head of an original reader for a facsimile device, an electronic mail transmitter, etc. The illumination variance of the original 8 is improved by a transparent pressure plate 11, and the light transmitted through the original 8 is received by an image sensor 12. This sensor 15 contains a photodetecting part 15, an electrode 16, a light shielding layer 17 insulated from the electrode 16 and a transparent protection layer 18. The layer 17 is formed into a slit to the part 15. Then the light transmitted through the original 8 is converted into electric signals by the sensor 12. Thus the resolution and the signal intensity of the original reader are increased, and the miniaturization of the reader is facilitated.

Description

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

(Background of the Invention) Conventional document reading devices such as facsimile machines are as shown in FIGS.
) is applied to the surface of the document (2), and the reflected and scattered light is received and read by an image sensor. Second
In the case shown in the figure, the original (2) is connected to a solid-state device (4) such as a COD using a condensing lens (3), which increases the size of the device and makes it difficult to adjust the focus. has the disadvantages of The one in Figure 3 uses a convergent optical fiber array (5) to project an image of the same size as the original onto an image sensor (6) to read the original (2). Sensor (6) is called a full contact type image sensor. Although this method makes the device somewhat smaller, it still has disadvantages in that it uses an expensive convergent optical fiber array (5) and that focusing is still complicated. Furthermore, in the case of FIG. 4, the light flux emitted from the light source (1) passes through an illumination window (7) provided in the image sensor board.
Illuminate the manuscript (2). The scattered light reflected by the original (2) is then read by an image sensor covered with an extremely thin transparent protective layer. An image sensor using this method (referred to as a contact image sensor) is a reading device using this method. It is lensless, compact, and does not require focusing, but on the other hand, it has high resolution because it reads the scattered light reflected on the surface of the document.

and is unsatisfactory for obtaining high signal strength.

(Object of the Invention) The object of the present invention is to solve the above-mentioned drawbacks, and to provide a document reading device that can obtain high resolution, high signal-to-noise ratio, and high signal strength, is compact, inexpensive, and extremely easy to manufacture and adjust. We are committed to providing this.

(Summary of the Invention) Therefore, the present invention provides a document reading method comprising a light source that illuminates a document from the background, and an image sensor that receives light emitted from the light source and transmitted through the document and converts it into an electric signal. Provide equipment.

(Example) An example of the present invention is shown in FIG. 1 below. The document (8) is sent to the gap between the contact type image sensor (b) and the transparent press plate (11) using the feed roller (9). Image sensor board (2)
The attachment is fixed to the base material (2). The main scanning direction of the image sensor (2) is perpendicular to the plane of the paper, and the light beam from the light source αQ parallel to this direction completely passes through the transparent press plate αυ and the document (8) and reaches the image sensor (2). .

At this time, the amount of light reaching the image sensor (2) changes depending on the information on the document (8), and this change is detected as an electrical signal.

In this case, if there is an image on both sides of the paper, the information on the front and back will overlap, so a double-sided manuscript is inappropriate, but in our daily life, when there is an image on only one side of the paper, There are a lot of them, so it's not that inconvenient. In addition, although books and bound documents are not applicable to this document reading device, once one-sided copies of these documents are prepared, this device can be used.

The degree of scattering of transmitted light varies depending on the paper quality of the original, and therefore,
Although the reading resolution of the original differs, for commonly used paper types, if the thickness of the paper is 150 μm to 200 μm or less, an image sensor with a 5 mcd light source and an 8 element/simplified element density is used. If used, the original can be read well.

When a light emitting diode array is used as the light source oQ, a scattering pressed plate may be used instead of the transparent pressed plate αυ in order to improve illumination unevenness. It is also possible to increase the illuminance by focusing the light beam onto the document surface using a converging optical system between the light source QO and the document (8), but this is not necessary for normal reading. On the other hand, it goes without saying that the document information can be read in a transmission manner even if an image sensor combined with a convergent optical system is used instead of the contact type image sensor (6).

However, if compact size and low cost are important, a device without a converging optical system is most advantageous.

FIG. 1A is an enlarged view of the image sensor section C1■,
A light receiving part Q made of a photoconductive material or a photoelectric conversion material is provided on the substrate α4.
A light shielding layer αη insulated from the Gai electrode aQ and the electrode αQ.

Transparent abdominal layer α barrels are formed one after another. The light shielding layer α is made to form a slit with respect to the light receiving part (2), and the interval is 10 μm to 300 μm, especially 30 μm.
When the thickness is set to 80 μm, manufacturing is easy and the resolution in the sub-scanning direction is also good. Further, the light-shielding layer αη may be formed on the outer surface of the transparent film-retaining layer θ pass, as shown in FIG. 1B. In both FIG. 1A and FIG. 1B, the substrate a4 is shielded from light.
It is designed to prevent external light other than the signal light from the original from entering the light receiving section (b).

This can be done by using a light-shielding substrate o1 for the mounting shown in FIG. 1, and covering the outer surface of the substrate a4 with a light-shielding film coat.

Fig. 1C shows electrode part height 1 when a photoconductive layer is used as a light receiving part.
It is connected so as to bridge the electrodes (total) and the individual electrodes. This is called a bridge method. Fig. 1D shows another example of electrode extraction. After forming the common electrode (6) on the substrate 04, the light receiving section 0 and the transparent individual IJ electrodes are laminated in this order. The light receiving portion a9 may be made of a photoconductive material or a photoelectric conversion material bonded with a PIN. Although this method requires a transparent electrode material for the electrode (a) and is greatly affected by pinholes during the manufacturing process, it is highly efficient and is suitable for both photoconductive and photoelectric conversion/conversion light receiving parts. also has suitable characteristics. In addition, when the individual electrode is on the substrate α → and the light receiving part α.

A similar image sensor can be obtained by stacking the transparent common electrode 01 in this order.

The light source (11) choppers to reduce the influence of external light and synchronizes with the light receiving section (2).
N ratio? It can also be made higher. Further, it is also possible to read a color original by sequentially lighting up a combination of three light sources of red, green, and one color as the light source α1. Of course, a color document can be read in the same way by using a near-white light source and using an array of light receiving elements having peak sensitivity in red, green, and blue in the light receiving section (b).

(Effects of the Invention) As described above, the present invention essentially eliminates the need for a converging optical system, has high reading ability, low power consumption, and is compact.
Light weight and easy to manufacture. Therefore, the present invention is highly portable, durable, and reliable, and is suitable for home facsimile machines, e-mail transmission devices, multiple facsimile machines, and document reading sections of copying machines.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a document reading device according to an embodiment of the present invention. FIG. 1A is a partially enlarged view of FIG. 1. Figure 1B, 1st
FIG. C and FIG. 1D are explanatory diagrams. 2 to 4 are perspective explanatory views of a conventional document reading device. [Explanation of symbols of main parts] 10...Light source 8...
・・・・・・・・・Manuscript 12・・・・・・・・・・・・
...Image sensor applicant Takashi Watanabe, agent of Nippon Kogaku Kogyo Co., Ltd.

Claims (1)

[Claims] A document reading device comprising: a light source that illuminates a document from behind; and an image sensor that receives light emitted from the light source and transmitted through the document and converts it into an electrical signal.