JPH09149200A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain read information correctly by reducing dispersion in a luminous quantity in an image read line. SOLUTION: An image light of an image of an original lighted indirectly by a lighting optical system of this reader using a light source 1 having plural light spots 4 is formed on a read means via an image forming optical system and then the image is read. The lighting optical system is provided with reflection members 2, 3 collecting and reflecting the light from the light source 1 and a light shield member 6 interrupting a direct light from the light source. Then the light shield member 6 is provided with a light shield section 6a extended to shut part of the indirect light at a position corresponding to each light spot 4 of the light source. Since an optical energy at a position corresponding to the light spot 4 is high without the absence of the light shield section 6a, the light shield section 6a shields the part to make it uniform with other parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus used in, for example, a color copying machine, a facsimile, or an input device of a computer, and more particularly to an image reading apparatus characterized by a structure of an illumination system for illuminating a document image. .

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus of this type is shown in FIG. That is, the image light of the original image is emitted from the light source 1, the reflecting members 2 and 3, and the first to third mirrors 1.
An image is formed through an image forming optical system composed of 4, 15, 16 and a condenser lens 17, and the reading element (C
A CD) 18 is arranged to read a document. Reference numeral 12 is a contact glass.

In such a structure, in order to perform high-speed reading, the accumulation time of the CCD must be set short, so that a light source of high brightness is required, and a light source such as a halogen lamp is conventionally used. It is used. On the other hand, there is an increasing demand for miniaturization of lighting systems to save space.

[0004]

However, as the optical path length from the light emitting point of a multi-point light emitting light source such as a halogen lamp to the document surface becomes relatively shorter than the distance between the light emitting points, the length direction of the light source becomes longer. There is a problem that a so-called ripple is generated, that is, the light amount distribution along the line becomes uneven. On the other hand, there is a method of shortening the distance between the light emitting points by increasing the number of light emitting points, but since the filament wire diameter has to be made thin, a side effect that reliability is deteriorated occurs.

This problem will be described in more detail.
When reading with an image reading device, it is common to perform reading using reflected light of an image due to the reflection of light from a light source, and this type of image reading device condenses light from the light source and saves light. We are trying to save electricity and space. In addition, the efficiency of light collection has been improved by increasing the need for high-speed reading. As shown in FIG. 4, the illumination optical system includes a light source 1 and reflecting members 2 and 3 for condensing the light from the light source, and condenses the light at a reading position 10 of the image reading device. . As the light source 1, a light source having a filament with a large amount of light, generally a halogen lamp or the like is used. A light source having a filament emits light at the position of the filament. Reference numeral 11 in the figure indicates the illuminance distribution at the image reading position 10.

Usually, the direct light from the filament is not focused at the reading position, but indirectly, for example, by the reflecting member 2,
3 is used so that the illuminance distribution at the image reading position has a smooth distribution state. Further, as an image reading, various originals such as a glossy original, an original with a step formed by cutting and pasting, an original with a fibrous pattern such as Japanese paper, and the like are faithfully read, so that a reflecting member is used. 2 and the reflection member 3 are arranged on the left and right sides of the reading position, and are arranged as far as possible from the light source 1 so as to obtain a uniform illuminance distribution with no strong directivity.

When a light source in which a plurality of filaments are arranged, such as a rod-shaped light source, is used, it is necessary that the illuminance distribution is uniform and smooth in the longitudinal direction of the light source 1. When the light source is a rod lamp having a filament, the light energy distribution as shown in FIG. 5 is obtained. Therefore, when performing image reading with a line width, it is necessary to consider the illuminance distribution in the longitudinal direction of the rod-shaped light source, and the light from the light source 1 is not directly applied to the reading position (line), First, the reflecting members 2 and 3 are irradiated, the reflected light from the reflecting members 2 and 3 is condensed at the image reading position, and the original image is read. In this configuration,
When the light from the light source 1 is focused on the image reading position, the distance from the light source 1 to the reading position varies depending on the light passing through the reflecting members 2 and 3. Light having a short distance from the light source 1 and arriving at the image reading position is applied to the image reading position while the light energy distribution due to the filament (light emitting point) is biased, which is disadvantageous in faithful reading of document information.

The present invention has been made on the basis of such a background, and solves the above-mentioned drawbacks of the conventional device, eliminates the variation of the light amount, and reduces the variation of the light condensing on the compact glass. An object is to provide an image reading device that can obtain accurate read information.

[0009]

According to a first aspect of the present invention, there is provided an image reading device for image light of a document image indirectly illuminated by an illumination optical system using a light source having a plurality of light emitting points. In the image reading apparatus for forming an image on the reading means through the image forming optical system to read an image, the illumination optical system includes a reflecting member that collects and reflects light from the light source, and a light shield that blocks direct light from the light source. It is characterized in that the light shielding member includes a light shielding portion extending so as to shield a part of the indirect illumination light at a position corresponding to each light emitting point of the light source. As a result, the light blocking member blocks the indirect illumination light at the position corresponding to each light emitting point of the light source, and suppresses the light on the document surface facing the light emitting point to obtain a uniform light amount distribution.

According to the second aspect of the present invention, the image light of the original image indirectly illuminated by the illumination optical system using the light source having a plurality of light emitting points is formed on the reading means via the image forming optical system. In the image reading device for reading an image, the illumination optical system corresponds to each of the light emitting points of the light source, the reflecting member that collects and reflects the light from the light source, the first light blocking member that blocks the direct light from the light source. A second light shielding member protruding and retracting from the tip of the light shielding member is provided so as to block a part of the indirect illumination light at the above position. As a result, the light on the document surface corresponding to the light emitting point is adjusted more accurately, and a more uniform light amount distribution is obtained.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of an image reading apparatus according to the present invention. FIG. 1 (a) is a perspective view showing a part of the image reading device, and FIG. 1 (b) is a side view thereof. is there. In the figure, 1 is a light source such as a halogen lamp,
A plurality of filaments 4 which are light emitting points are provided along the longitudinal direction. The reflection members 2 and 3 are installed below and in front of the light source 1 with the reading position sandwiched, as in the conventional configuration. The light shielding member 6 has an L-shape that covers the upper part of the light source 1, and a semicircular light shielding portion 6 a is formed in the front at a position corresponding to each filament 4 of the light source 1. As shown in FIG. 1B, the light shielding portion 6a functions to block a part of the light directly below the filament 4 which is reflected by the reflecting member 2 and is irradiated to the contact glass 5 side. Therefore, the light in this portion is dimmed and approaches the light amount in the other portion (the portion away from the filament 4), and the illuminance distribution 11 of the original reading line 10 in the longitudinal direction of the light source 1 is uniform and has a smooth distribution. Become.

2A and 2B are views showing a second embodiment of the image reading apparatus according to the present invention. FIG. 2A is a perspective view thereof and FIG. 2B is a side view thereof. In this embodiment,
The second light blocking member 7 is provided on the light blocking member 6 having the same structure as the conventional one.
Is arranged, and it can freely appear and disappear in the direction of the image reading line. The second light-shielding member 7 is provided with convex portions 7a at several points at its tip, and the convex portions 7a are formed so as to correspond to the positions of the filaments 4 of the light source 1. Therefore, the first
Similar to the embodiment described above, a part of the light that is reflected from immediately below the filament 4 and is about to enter the image reading line is blocked, and the light amount of the other part is made uniform. In this embodiment, by moving the second light shielding member 7 relative to the light shielding member 6, the amount of light to be emitted to the reading device side can be adjusted. The second light blocking member 7 can be moved and fixed to the light blocking member 6 by any conventional method.
For example, a long hole can be provided in the light blocking member 7 and the light blocking member 7 can be fixed to the light blocking member 6 with a screw.

[0013]

As described above, in the image reading apparatus according to the first aspect of the present invention, the light shielding member is formed with the light shielding portion so as to block the indirect illumination light at the position corresponding to each light emitting point of the light source. Since the light amount on the document surface corresponding to the light emitting point is suppressed, a uniform light amount distribution can be obtained, and as a result, the light path can be set shorter, so that a small illumination system can be configured. There is an effect.

In the image reading apparatus of the second aspect,
As described above, since the second light blocking member is provided so as to be movable with respect to the first light blocking member, it is possible to adjust the light amount more accurately and prevent the light amount from being lowered more than necessary. The effect is that you can do it.

[Brief description of the drawings]

1A and 1B are views showing a first embodiment of an image reading apparatus according to the present invention, FIG. 1A is a partially cutaway perspective view, and FIG. 1B is a side view thereof.

2A and 2B are diagrams showing a second embodiment of an image reading apparatus according to the present invention, FIG. 2A is a perspective view thereof, and FIG. 2B is a side view thereof.

FIG. 3 is a diagram showing an overall configuration of a conventional image reading device.

FIG. 4 is a side view showing a conventional image reading device.

FIG. 5 is a diagram showing a relationship between a filament position and a light energy distribution in a conventional image reading apparatus.

[Explanation of symbols]

 1 Light source 2, 3 Reflecting member 4 Filament 5 Contact glass 6 Light-shielding member 6a Light-shielding part 7 Second light-shielding member

Claims (2)

[Claims] 1. An image reading apparatus for reading an image by forming image light of a document image indirectly illuminated by an illumination optical system using a light source having a plurality of light emitting points on a reading means through an imaging optical system to read the image. In the device, the illumination optical system includes a reflecting member that collects and reflects light from a light source, and a light blocking member that blocks direct light from the light source, and the light blocking member has a position corresponding to each light emitting point of the light source. An image reading apparatus having a light-shielding portion that extends so as to block a part of indirect illumination light. 2. An image reading method for forming an image of a document image, which is indirectly illuminated by an illumination optical system using a light source having a plurality of light emitting points, on a reading means through an imaging optical system to read the image. In the device, the illumination optical system includes a reflection member that collects and reflects light from a light source, a first light blocking member that blocks direct light from the light source, and an indirect illumination light at a position corresponding to each light emitting point of the light source. An image reading apparatus comprising a second light shielding member protruding and retracting from a tip of the light shielding member so as to partially block the light shielding member.