JPS6332532A - Document illuminating device - Google Patents

Abstract

PURPOSE:To make the device thin and small in size by using a light transmissive plate-shaped body having a refractive index distribution in the thickness direction, as a line surface light source converting optical system. CONSTITUTION:As for a light transmissive plate-shaped body 11 of an acryl resin, its refractive index becomes higher as it goes toward the upper face, therefore, an incident light from the side is curved to the upper face. By a light source 10 which has been placed so as to be opposed to the side end face of the plate-shaped body 11, a document 1 is irradiated extending over the whole surface, and reflected light beams pass through the plate-shaped body 11 in the lower direction, brought to a photoelectric conversion by a two-dimensional arrangement photodetector array 12 which has been placed adjacently on the lower face, and fetched as an electric signal to the outside. By this array 12 and a structure of a document illuminating device, the device can be made small and thin in size.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a document illumination device used in a two-dimensional image reading system fK using, for example, two-dimensionally arranged photoelectric conversion elements.

[Background of the invention]

The schematic structure of a conventional image reading device will be explained using an example shown in FIG. 6. In this case, 1 is an original and water is used. 2 is a lamp such as a fluorescent lamp for illuminating the original, and 3 is a reflective shade for efficiently focusing the light from the lamp 2 onto the original surface. Reference numeral 4 denotes a lens array that forms an image of reflected light (light image) from the original 1 onto a light receiving element (photoelectric conversion element) array 5. 6 is a light receiving element array driving circuit, and 7 is an interface circuit for exchanging signals with external equipment. The light-receiving element array 5 is composed of fine photoelectric conversion elements arranged in a row (one-dimensional), and therefore has two
In order to read the dimensional information, it is necessary to scan the reading head equipped with each of the components 2 to 6 described above in the direction of the arrow in FIG. 6, or to scan the document table 8 in the same direction as the arrow. , the example in FIG. 6 shows the configuration in the former case.

In this way, an image reading device using a one-dimensional light-receiving element array requires mechanical scanning means), and it is difficult to miniaturize the device (particularly as it becomes thicker). There was a limit to image reading speed.

Therefore, by using a two-dimensional light-receiving element array in which light-receiving elements are two-dimensionally arranged in a plane, it is possible to eliminate the mechanical scanning mechanism described above, make the device smaller (thinner), and enable high-speed image reading. Conceivable.

However, in order to realize this method, it is necessary for K to simultaneously realize document illumination and image formation of reflected light (light image) on the light receiving element between the document and the destination element, but such an illumination device This method has not been proposed in the past, and as a result, it is necessary to use a method of irradiating light from the back side of the document, which has the disadvantage that the document is limited to thin sheets.

The present invention has been made in view of the above-mentioned current situation, and an object of the present invention is to provide a fixed document illumination device that can illuminate a document image from the 9th side of the document to be read without hindrance to the operation. be.

Another object of the present invention is to provide a document illuminating device that enables two-dimensional illumination and reading without being limited by the type of document.

Still another object of the present invention is to provide an original illumination device that can be conveniently used for high-speed reading of color originals.

[Summary of the invention]

A feature of the document illuminating device according to the present invention, which has been made to achieve such an object, is that the document illuminating device is used for reading 9 a document placed on a fixed document table, and the document illuminating device is used for reading a document placed on a fixed document table from one side in the thickness direction. A line-to-plane light source conversion optical system consisting of a translucent plate-like body having a configuration in which the refractive index is continuously or stepwise reduced by #i toward the Noh mask side is applied to the entire surface of the manuscript with the one surface side A linear light source for document illumination is fixedly arranged opposite to the side end surface of the translucent plate-like body which is the linear-to-plane light source conversion optical system.

The transparent plate-like body, which is the linear-to-plane light source conversion optical system, can also serve as a fixed document table as it is.

In the line-to-plane light source conversion optical system in the above configuration, a plate-like body of a predetermined thickness is formed using a translucent material such as acrylic, and this plate-like body is formed from one side to the other side in the thickness direction. It is assumed that the refractive index changes from high to low. The change in the refractive index may be continuous or stepwise.

In addition, the degree of change in the refractive index, the thickness of the plate, etc. are determined depending on the material used, the dimensions of the image reading device, etc.; As the size increases, the thickness increases. (For example, 8 m below B3.

B3-B2: 10 simple, B2-15 gourd), and since this device applies the structure of an optical fiber, the refractive index distribution of the material is given according to the optical fiber production technology and its structure. .

[Embodiments of the invention]

The present invention will be described below based on embodiments shown in the drawings.

Figure 1 shows an example of the configuration of an image reading device, in which 1 is a document (book), and 11 is a translucent plate-like body serving as a line-to-plane light source conversion system that also serves as a document placement table. It is made of acrylic resin. As shown in FIG. 3, this translucent plate-like body 11 is given an oil irradiation coefficient distribution in the thickness direction d, so that the side root refractive index of the surface (upper surface) is high. Therefore, incident light from the side is bent toward the surface as shown in FIG.

Reference numeral 10 denotes a light source (fluorescent lamp) disposed opposite to the side end surface of the translucent plate 11, which emits light from the surface of the translucent plate 11 (upper surface in FIG. 2). In order to make the light uniform over the entire surface, it is preferable that the light from the light source be scattered to some extent. As a result, the entire surface of the document closely attached to the surface of the translucent plate 11 is illuminated, and the reflected light passes through the translucent plate 11 downward.

Reference numeral 12 denotes a two-dimensional array of light receiving elements arranged closely along the lower surface of the transparent plate-like body 11, and the reflected light is photoelectrically converted by this array K and taken out to the outside as an electric signal.

The two-dimensional light-receiving element array is configured, for example, as shown in FIG. The switching control terminal and the other end to which the photodiode 20 is not connected are wired in a matrix. The wiring ends are connected to a vertical driver 22 and a horizontal driver 23, respectively. In this example, the switching elements of the vertical lines are sequentially activated by the vertical driver 22, and the data from the optical image of each row is taken into the horizontal driver 23 and outputted as an external output.

When using such a two-dimensional array of light-receiving cables,
Naturally, a mechanical scanning function is not required, and in harmony with the structure of the document illumination device, compact and high-speed image reading is possible.

In FIG. 1, reference numeral 13 indicates a drive circuit for a two-dimensional array of light receiving elements, and reference numeral 14 indicates an interface circuit for controlling signal transmission with external equipment. Both circuits are connected to the cable 1.
5 is electrically wired.

According to this embodiment having the above configuration, the document illumination device
Because the document can receive illumination and reflection from the same direction, it is not limited by the type of document as in the past, and has the advantage that image reading with a fixed device can be done quickly and stably. It will be done.

Incidentally, the refractive index distribution of the line to surface light source conversion optical system used in the above embodiment is not limited to that shown in FIG. 3, and may be, for example, a stepwise distribution.

Further, a second light source used in combination with the document illumination device
It goes without saying that the dimensionally arranged light receiving element array is not limited to that of the embodiment described above, and that other types such as a CCD type can also be used.

FIG. 5 shows a document illuminating device according to the present invention configured for full-color image reading.

The configuration of the full-color image reading device shown in FIG. 5 is as follows:
Compared to the monochrome image reading device shown in FIG. 1, this device is the same except for the configuration of the light source, so the same parts are given the same reference numerals and the explanation will be omitted.

A feature of the device shown in FIG. 5 is that red, green, and blue light sources 30a, 30b, and
It is located where a set of 0 is placed.

If such three color light sources are selectively and sequentially turned on by a control circuit (not shown) and the image is read, a color-separated document image can be read.

In addition to the above-mentioned configuration, such a document illumination device for full-color image reading may be configured by, for example, combining a light source containing light of three primary colors (for example, a white light source) and filters of the three primary colors, and selectively changing the filter ( For example, it may be configured in the current state and rotated.

A full color image reading device with such a configuration.

This is a dramatic improvement in reading compared to the conventional three-time document scanning method or the method in which multiple types of filters with sensitivity to specific wavelengths are placed on a two-dimensional array of light receiving elements at the expense of resolution. The effects of increased speed, stable operation due to the absence of mechanically moving parts, and improved resolution are achieved.

〔Effect of the invention〕

As explained above, the document illumination device for reading in the image reading device according to the present invention uses a translucent plate-like body with a refractive index distribution as a line light source and a line to surface light source conversion optical system. It has the effect of making small, thin and high-speed image reading possible regardless of the type of document, and the effect when applied to full-color image reading is extremely young.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an example of an overview of the configuration of an image reading device including an original illuminating device according to the present invention, and FIG. 2 shows the progress of light from a line that also serves as a document placement table to a surface light source conversion optical system. Figure 3 is a diagram showing the relationship between the thickness and refractive index of a line to surface light source conversion optical system, and Figure 4 is a diagram showing an example of the configuration of a two-dimensional optical element array. Figure 5 shows the present invention 1...
・Manuscript (book) 2... Lamp 3... Reflective shade
4... Lens array 5... Light receiving element (photoelectric conversion element) array 6... Light receiving element array drive circuit 7... Interface circuit 8... Document table 10... Fluorescent lamp 11...
Line-to-plane light source conversion optical system 12...2 (also serves as document table)
Dimensional array light receiving element array 13...Drive circuit 14...Interface circuit 15...Wire 20...Photodiode 21...Switching transistor 22...Vertical driver 23...Horizontal driver 30a...・Red light source 30b...green light source 3
0e... Blue light source. Agent: Teruo Taniyama ・1.・Knee fτ] Tani Kotabe 1, J Figure 1 Figure 2 (back side) Awesome d (dragon face)

Claims (1)

[Scope of Claims] 1. A document illumination device used for reading a document placed on a fixed document table, in which the refractive index gradually decreases continuously or stepwise from one side to the other side in the thickness direction. A line-to-plane light source conversion optical system made of a translucent plate-like structure is arranged with the one surface side facing the entire surface of the read document, and the line-to-plane light source conversion optical system is a light-transmitting optical system. 1. A document illuminating device characterized in that a linear light source for document illumination is fixedly arranged opposite to a side end surface of a flexible plate-like body. 2. The document illumination device according to claim 1, wherein the light-transmitting plate-like body that is the line-to-plane light source conversion optical system also serves as a fixed document table.