JP2000137303A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image reader constituted so that the quantity of light emitted from plural illumination means can be always equally corrected in the image reader having the plural illumination means. SOLUTION: This image reader is provided with at least two illumination means 2a and 2b illuminating the image of an original 1, a detection means 7 detecting the quantity of light emitted from the illumination means 2a and 2b and a light control means 8 correcting the quantity of light emitted from the illumination means 2a and 2b according to the detected value of the detection means 7. Then, the light control means 8 is constituted so that the quantity of light emitted from the illumination means 2a and 2b are independently detected by the detection means 7 and independently corrected according to the respective detected values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reading an image by illuminating a document with illuminating means, and more particularly to an image reading apparatus used in a copying machine having at least two illuminating means.

[0002]

2. Description of the Related Art Conventionally, in this type of image reading apparatus, the illuminating means such as a fluorescent lamp or a xenon lamp has a light amount detecting means such as a light amount sensor because the irradiation light amount changes due to environmental temperature change or aging change. The tube current of the illuminating means has been adjusted so that the illuminating light quantity by the illuminating means has a predetermined value corresponding to the illuminating light quantity of the illuminating means detected by the light quantity sensor.

[0003]

However, in the above-described conventional example, even in an image reading apparatus provided with two or more illuminating means, the amount of illuminated light combined by the two illuminating means is set to a predetermined value. Since the tube current was adjusted,
In some cases, the illuminating light amounts of the respective illumination means alone were not equal to each other. This is because the illuminating means such as a xenon lamp and a fluorescent lamp do not have the same irradiation light amount even if the same tube current is supplied due to individual differences and environmental temperature differences. Therefore, in the case of a folded document or a pasted document 1 'as shown in FIG. 2, when illuminating the pasting border 1a', if the xenon lamp 2a has a larger irradiation light amount than the xenon lamp 2b, the pasting is performed. There is a problem that a shadow is generated at the boundary 1a '. FIG. 2 is a diagram for explaining a problem of the conventional image reading apparatus.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and provides an image reading apparatus having a plurality of illuminating means, which can constantly correct the irradiation light amounts of these illuminating means equally. The purpose is to do.

[0005]

In order to achieve the above object, an image reading apparatus according to a first aspect of the present invention comprises at least two illuminating means for illuminating an image of a document, and a light amount of the illuminating means. In an image reading apparatus comprising: a detecting unit for detecting, and a dimming control unit that corrects an irradiation light amount of the illumination unit according to a detection value of the detection unit, the dimming control unit detects the irradiation light amount of the illumination unit. It is characterized in that the detecting means independently detects the light amount, and the irradiation light amount of each of the illuminating means is independently corrected in accordance with each detected value.

According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the detecting means for detecting the irradiation light amount of the illumination means is an imaging means.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a schematic configuration diagram showing an embodiment of an image reading apparatus according to the present invention.
In FIG. 1, 1 is a document, 2a and 2b are xenon lamps as illuminating means, 3 is a standard density member serving as a standard of image density, 4 is a platen glass, 5 is a first scanning table, 6 is a second scanning table. , 11, 12, and 13 are mirrors for guiding the reflected light from the original 1 to a predetermined optical path, 14 is a lens for condensing the reflected light guided to the optical path, and 7 is a detector for detecting the amount of light emitted from the illumination means 2a and 2b. An image sensor as a detecting means, for example, a CCD device, and 8 indicates a dimming controller for controlling the tube current of the xenon lamps 2a and 2b.

An image reading area A and a density measuring area B of the original 1 are illuminated by an illumination system including two xenon lamps 2a and 2b.
And mirror 11 reflects the reflected light from the original 1
While bending the optical path at 12 and 13, CCD at lens 14
An image of the document 1 is formed on the light receiving surface 7a of the element 7. The first scanning table 5 and the second scanning table 6 surrounded by broken lines scan at a speed ratio of 2: 1 and read the entire area of the document 1. The image of the document 1 formed on the light receiving surface 7a of the CCD element 7 is converted into image data as is known.

The dimming control unit 8 includes the xenon lamps 2a, 2a
b is illuminated on the document 1 alone, the single reflected light in the density measurement area B is detected by the CCD element 7, and the xenon lamps 2a and 2b are set so that each of the xenon lamps 2a and 2b has a predetermined irradiation light amount. , 2b are adjusted. That is, the dimming control unit 8 independently detects the irradiation light amount of the xenon lamps 2a and 2b by the CCD element 7, and independently corrects the irradiation light amount of the xenon lamps 2a and 2b according to each detection value. Thus, the irradiation light amounts of the two xenon lamps 2a and 2b can always be corrected equally.

[0011]

As described above, according to the image reading apparatus of the first aspect, at least two illuminating means for illuminating the image of the original, detecting means for detecting the amount of light emitted by the illuminating means, A dimming control unit that corrects an irradiation light amount of the illumination unit in accordance with a detection value of the unit, wherein the dimming control unit independently detects the irradiation light amount of the illumination unit by the detection unit. However, by independently correcting the irradiation light amount of each of the illumination units according to each detection value, it becomes possible to always correct the irradiation light amounts of a plurality of illumination units equally, such as a document with a fold,
Even in a pasted document or the like, a shadow is not generated on the read image.

According to the image reading apparatus of the present invention, the detecting means for detecting the irradiation light amount of the illumination means can be quickly and accurately detecting the irradiation light amount by using an imaging means. Further, it is small and lightweight, and can be easily provided in the apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an image reading apparatus according to the present invention.

FIG. 2 is a diagram illustrating a problem of a conventional image reading apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Original 2a, 2b Xenon lamp (illuminating means) 3 Standard density member 4 Original table glass 5 First scanning table 6 Second scanning table 7 CCD element (imaging means as detecting means) 8 Light control sections 11-13 Mirror 14 lens

Claims (2)

[Claims] At least two illuminating means for illuminating an image of a document, a detecting means for detecting an illuminating light quantity of the illuminating means, and a control means for correcting the illuminating light quantity of the illuminating means according to a detection value of the detecting means. An image reading device comprising: a light control unit; wherein the dimming control unit independently detects an irradiation light amount of the illumination unit by the detection unit, and irradiates the irradiation light amount of each of the illumination units in accordance with each detection value. An image reading apparatus for independently correcting image data. 2. An image reading apparatus according to claim 1, wherein said detecting means for detecting the amount of light emitted from said illuminating means is an imaging means.