JPH05292254A - Original reader - Google Patents

Abstract

PURPOSE:To attain miniaturization by providing a bar shape light source which illuminates { original. an image reading means, and an optical means which guides reflected light from an original surface to the image reading means, and providing bending parts at two terminals of the bar shape light source, respectively. CONSTITUTION:Contact glass 4 on which the original 3 is placed is provided at the upper part of a device main body 1, and it is fixed with a stopper 6. Also. U-shape Xe lamps provided with the bending parts of 90' or the light source 2 of a fluorescent lamp are arranged in the inside of the device main body 1 with a supporting body 5 neighboring to the contact glass 4. The entire length Y of the light source 2 is set nearly equal to the width of the original. The image on the original surface can be read by irradiating the surface of the original 3 with light from the light source 2 and receiving the reflected light from the surface by a CCD. In such a case, assuming the angle of the bending part as theta, the length of the bending part as Z, and substituting compacted length DELTAX for the entire length Y of the light source 2, it is expressed in DELTAX=2Z(1-costheta), and the length of the light source 2 can be reduced by DELTAX, therefore, the miniaturization by that share can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading device mounted on a facsimile machine, a copying machine, a scanner or the like.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. As shown in FIG. 3, the type of the document reading device is often used in a facsimile device, in which the document 3 moves on a fixed light source 2, and as shown in FIG. 4, it is often used in a copying machine. The light source 2 is moved below the original 3 placed on the contact glass 4.

In both of these types, the rod-shaped light source 2 is used to irradiate the original 3 with light, and the reflected light from the original 3 is coupled onto the CCD 9 through optical means such as the mirror 7 and the reading lens 8. Image 3 and photoelectric conversion
The image is read.

Further, as shown in FIG.
A light source longer than (L in the figure) is used. That is, as shown in FIG. 6, it can be seen that the illuminance of the document surface illuminated by the light source decreases as it goes to the document surface corresponding to the edge of the light source, and the illuminance distribution is non-uniform. However,
If the illuminance is not uniform in the range of the document width L, as shown in FIG. 7, the total amount of light is defined by the minimum value of the illuminance within the document width L, and therefore the portion higher than the minimum value (hatched portion in the figure). Is treated as noise and cut, which leads to deterioration of the image. Therefore, in order to make the illuminance within the document width L uniform, it is necessary to make the entire length of the light source 2 (X in the drawing) longer than the document width L by about 80 mm.

By the way, recently, facsimile machines and copying machines have become popular not only in companies but also in homes. Therefore, there is a demand for downsizing of the device from the viewpoint of space saving.

[0006]

The length of the light source is the most important factor in downsizing a facsimile machine or a copying machine. The size of the original reading device in the reading width direction is largely related to the length of the light source. Therefore, in order to reduce the size of the apparatus, it is conceivable to reduce the size of the light source itself. However, reducing the size of the light source leads to a reduction in the illuminance on the document surface.
As a result, the amount of light reflected from the document surface is reduced. In order to compensate for the reduced light amount, it is conceivable to use a bright lens with a small F value or a CCD with higher sensitivity as the reading lens, but this leads to an increase in cost because the parts are expensive. It is also conceivable to install the light source close to the document surface, but in that case, the support for supporting both ends of the light source becomes an obstacle, and there is a limit to the approach distance.

SUMMARY OF THE INVENTION It is an object of the present invention to solve such problems and provide a smaller document reading device.

[0008]

In order to achieve the above-mentioned object, the present invention provides a rod-shaped light source for illuminating a document surface, an image reading means for receiving reflected light from the illuminated document surface, and the reflection. An original reading apparatus provided with an optical means for guiding light to the image reading means, wherein the light source has bent portions at both ends thereof, and further, a Xe lamp or a fluorescent lamp is used as the light source. is there.

[0009]

By providing the bent portions at both ends of the light source, the original surface is illuminated so that the original surface has a uniform illuminance, and the total length of the light source can be shortened by the amount of the bent portions at both ends. It will be possible. Further, since the size of the support for supporting both ends of the light source and applying a voltage is not a factor for determining the distance between the light source and the document surface, the light source can be installed close to the document. ..

Further, by using a Xe (xenon) lamp or a fluorescent lamp as the light source, both ends of the light source can be easily bent.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. The same members as those in the conventional example are designated by the same reference numerals. FIG. 1 shows an embodiment of the present invention.
Is an apparatus main body, 2 is a light source, and uses an Xe lamp or a fluorescent lamp. Reference numeral 3 is a document, 4 is a contact glass, and is a table on which the document 3 is placed. A support 5 supports both ends of the light source 2. A contact glass 4 is provided on the upper part of the apparatus main body 1, and is fixed by a stopper 6. Inside the apparatus body 1, a U-shaped light source 2 having bent portions of 90 degrees at both ends is installed close to the contact glass 4 by a support body 5. The total length (Y in the drawing) of the light source 2 is substantially equal to the document width (L in the drawing).

Then, as in the conventional example, the light source 2 is the original 3
The surface of the document is irradiated with light, and the light reflected by the document surface is received by the CCD, whereby the image on the document surface is read.

Next, another embodiment will be described. In another embodiment, the light source 2 of the first embodiment has bent portions of 90 degrees at both ends, but as shown in FIG. 2, the light source 2 is bent at an angle θ (0 <θ <90 °). A light source having a section is used.

The method of reading the original 3 is the same as in the conventional example. Next, the operation will be described. As shown in FIG. 2, if the angle of the bent portion is θ, the length of the bent portion is Z, and the shortened length of the light source 2 is ΔX, ΔX
Can be expressed by the following formula.

[0015]

ΔX = 2Z (1-cosθ) (0 <θ ≦ 90 °) That is, since the light source 2 can shorten the length of ΔX,
The size can be reduced accordingly. Further, since the position of the support 5 is also lowered by Zsinθ, the support 5 does not hinder the approach of the light source 2 to the original 3 by that amount.

In particular, in the first embodiment, since θ = 90 °, ΔX becomes the maximum, the total length Y of the light source 2 can be shortened most, and the light source 2 on the original 3 is close to the thickness of the contact glass 4. It is possible to bring them closer.

[0017]

According to the present invention, the total length of the light source can be shortened by providing the bent portions at both ends of the light source. Further, since the light source can be brought closer to the document surface, it is possible to illuminate the document surface with a high and uniform illuminance. Therefore, it is possible to reduce the size of the device without degrading its performance.

Further, since the Xe lamp or the fluorescent lamp can be bent, the light source can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a document reading apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a light source of a document reading device according to another embodiment of the present invention.

FIG. 3 is a main part configuration diagram of a conventional document reading apparatus of a type that moves a document.

FIG. 4 is a main part configuration diagram of a conventional document reading apparatus of a type in which a light source is moved.

FIG. 5 is a diagram showing a length of a light source with respect to a document width of a conventional example.

FIG. 6 is a diagram showing an illuminance distribution corresponding to the length of a light source in the conventional example.

FIG. 7 is a diagram showing a variation in illuminance distribution on the same document surface.

[Explanation of symbols]

2 ... Light source, 3 ... Original, 7 ... Mirror, 8 ... Read lens, 9 ... CCD.

Claims (3)

[Claims] 1. A rod-shaped light source for illuminating a document surface, an image reading means for receiving reflected light from the illuminated document surface,
An original reading device comprising an optical means for guiding the reflected light to the image reading means, wherein the original reading device has bent portions at both ends of the light source. 2. The document reading apparatus according to claim 1, wherein the light source is an Xe lamp. 3. The document reading apparatus according to claim 1, wherein the light source is a fluorescent lamp.