JPH04171436A - Document illuminating device for image reader - Google Patents

Abstract

PURPOSE:To obtain sufficient sensitivity even in the case of reading the image of a color document of high density value by providing a slit for radiating the light reflected by a reflecting member and the light emitted from light source, toward the surface of a document and specifying the width of the slit in relation to that of an optical line sensor. CONSTITUTION:A slit 9a for radiating the light reflected by the inner peripheral surface of a reflector 9 and the light emitted directly from a fluorescent lamp 8, toward a document 3 is bored at the part, corresponding to the detecting part of an optical line sensor 7, of the reflector 9. The maximum effect can be obtained by setting the width measure of this slit 9a in relation to the element width measure of the optical line sensor 7 in such a way that the width of the light after passing an image focusing lens 6 becomes approximately three times larger than before. Constantly sufficient light quantity can be thereby obtained even in the case of using a fluorescent lamp or the like as light source, and sufficient sensitivity can be obtained even in the case of reading the image of a color document of high density value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a document illumination device used in an image reading device that can optically read a document image using an optical line sensor (for example, an image sensor). .

[Prior art]

There are five conventional light sources for this type of document illumination device.

-Fluorescent lights are used for boat fishing.

The fluorescent lamp is arranged in the longitudinal direction of the optical line sensor in correspondence with the detection section of the optical line sensor so as to irradiate light onto the surface of the document placed on the document table.

Then, the document table on which the document is placed is relatively moved in a direction substantially perpendicular to the main scanning direction of the optical line sensor, and light is irradiated from the fluorescent lamp onto the surface of the document. In this state, the images of the document are sequentially optically read by the optical line sensor.

[Invention tries to solve it! i! M:1 By the way, color filters are used for color separation in image reading devices for color images for boat fishing, but image reading devices equipped with an original illumination device using a fluorescent lamp as a light source as described above In the reading device, the amount of light incident on the optical line sensor is significantly reduced by the color filter, so when reading a color original with a relatively high density value (for example, density 3.0), it is necessary to avoid insufficient light amount. There was a problem in that it was not possible to obtain sufficient sensitivity.

Therefore, it is an object of the present invention to always obtain a sufficient amount of light even when a fluorescent lamp is used as a light source, and to provide sufficient sensitivity even when reading an image of a color original with a high density value. An object of the present invention is to provide a document illumination device for an image reading device that can obtain the following.

[Means to solve the problem]

5 The main means adopted by the present invention in order to achieve the above object are 1. The gist thereof is to move the document relatively in a direction approximately perpendicular to the main scanning direction of the optical line sensor, and to image the document. In a document illumination device of an image reading device that irradiates light from a light source onto the surface of the document in order to cause the surface of the document to be sequentially read by the optical line sensor, a document illumination device is provided that is configured to reflect the light emitted from the light source inward. A reflective member covers the light source, and a portion of the reflective member corresponding to the detection section of the optical line sensor,
A document of an image reading device according to the aspect that a slit having a predetermined width is provided with respect to the width of the optical line sensor in order to irradiate the light reflected by the reflection member and the light emitted from the light source toward the document surface. It is a lighting device.

[Effect]

In the document illumination device according to the present invention, the light emitted from the light source is reflected inward by the reflective member around the light source, and this reflected light and the light directly emitted from the light source pass through the slit. Irradiation is directed toward the surface of the original.

As a result, the amount of light on the document surface is significantly increased compared to when a fluorescent lamp is simply used as a light source.[Examples] Two embodiments embodying the present invention will be described below with reference to the attached drawings. Provide for understanding of the invention. still.

The following examples are examples embodying the present invention, and are not intended to limit the technical scope of the present invention.

Here, FIG. 1 is a perspective view of a document illuminating device according to an embodiment of the present invention, and FIGS. 2 and 3 are perspective views of a fluorescent lamp and a reflecting member as a light source constituting the document illuminating device. FIG. 4 is a schematic diagram of a main part of an image reading apparatus equipped with the above document illuminating device, and FIG. 5 is a chart showing comparison data of the amount of light between the above document illuminating device and a conventional document illuminating device.

In the image reading apparatus 1 according to this embodiment, for example, as shown in FIG. 4, an original 3. Mirror 41 color filter 5. It is constructed by including an imaging lens 6, an optical line sensor 7, etc. in that order.

In this embodiment, the document illumination device 2 has its axial direction corresponding to the detection section of the optical line sensor 7;
It is arranged on the opposite side of the document 3 to the optical line sensor 7, and utilizes the transmitted light.

In addition, when using reflected light in the device.

The document illumination device 2 is arranged on the same side of the document surface of the document 3 as the optical line sensor 7 .

In the document illuminating device 2 (see FIG. 1), its light source is, for example, an aperture-type fluorescent lamp 8 (see FIG. 2). The overall length is approximately 300 mm), and a substantially cylindrical reflector 9 is used to cover the outer circumferential surface of the reflector.
(See Figure 3) is installed. The reflecting plate 9 is made of, for example, an aluminum member, and has an inner circumferential surface polished to a mirror finish, and functions to reflect the light emitted from the fluorescent lamp 8 inward. The light reflected by the inner peripheral surface of the reflector 9 and the light directly emitted from the fluorescent lamp 8 are transmitted to the portion of the reflector 9 corresponding to the detection section of the optical line sensor 7 on the original 3.
A slit 9a is provided for irradiating light toward.

The width of the slit 9a is set so that the width of the light after passing through the imaging lens 6 is about three times the width of the element of the optical line sensor 7 (for example, 2 steel). 3s+m) is most effective.

However, the above slit 9. It goes without saying that the width dimension of is not limited to the above value.

As described above, since the width dimension of the illumination light from the slit 98 is set to a value larger than the width of the detection section (width of the element) of the optical line sensor 7, the original illumination device W2 is particularly The adjustment work of the optical system of the optical line sensor 7 can be performed relatively easily.

Note that when flare light is generated due to irradiation of illumination light with a width wider than the width dimension of the detection section of the optical line sensor 7, the above The detection part of the optical line sensor 7 is set at a predetermined angle (
For example, a countermeasure is taken by tilting it at an angle of 45 degrees.

The document illumination device 2 according to this embodiment is configured as described above.

Therefore, the image reading device 1 equipped with the above-mentioned document illumination device 2
In the slit 9., the light emitted from the fluorescent lamp 8 is reflected inward by the reflecting plate 9 around the fluorescent lamp 8, and this reflected light and the light directly emitted from the fluorescent lamp 8 pass through the slit 9. The light is irradiated onto the document 3 through the light source. In this state, the original 3 is relatively moved in a direction substantially perpendicular to the main scanning direction of the optical line sensor 7, and the images of the original 3 are sequentially read by the optical line sensor 7.

As a result, in the apparatus of this embodiment, the amount of illumination light on the surface of the document 3 is significantly increased compared to when a fluorescent lamp is simply used as a light source, and a sufficient amount of light can always be obtained. Therefore, sufficient sensitivity can be obtained even when reading, for example, an image of a color original with a high density value.

FIG. 5 shows comparison data of the amount of illumination light between the document illuminating device 2 according to the present embodiment and a conventional document illuminating device using only a fluorescent lamp.

In this case, the amounts of illumination light obtained by the conventional document illumination device without a reflector as described above are set as 100, and the respective flights are compared.

Furthermore, in the device of this embodiment, excellent effects can be produced only by providing the cylindrical reflector 9 around the fluorescent lamp 8 as described above, so that the installation space can be kept relatively compact. In addition, since the structure is simple, there is no need to significantly increase costs or increase the size of the entire device.

〔Effect of the invention〕

As described above, the present invention moves a document relatively in a direction substantially perpendicular to the main scanning direction of the seven optical line sensor,
In a document illumination device of an image reading device that irradiates light from a light source onto the surface of the document in order to sequentially read images of the document by the optical line sensor, the light emitted from the light source is reflected inward. The light source is covered with a reflective member so as to obtain the light source, and a portion of the reflective member corresponding to the detection portion of the optical line sensor is provided.

An image reading device characterized in that a slit having a predetermined width is provided relative to the width of the optical line sensor so that the light reflected by the reflecting member and the light emitted from the light source are irradiated toward the document surface. Because it is a document illumination device, it is possible to always obtain a sufficient amount of light even when using, for example, a fluorescent lamp as a light source, and it is possible to obtain sufficient sensitivity even when reading, for example, an image of a color document with a high density value. can.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a document illumination device according to an embodiment of the present invention, FIGS. 2 and 3 are perspective views of a fluorescent lamp and a reflecting member as a light source constituting the document illumination device, and FIG. FIG. 5 is a schematic diagram of a main part of an image reading apparatus equipped with the above-mentioned original illuminating device, and a chart showing comparison data of the amount of light between the above-mentioned original illuminating device and a conventional original illuminating device. [Explanation of symbols] 1...Western image reading device 2...Document illumination device 3...Document 7...Optical line sensor 8...Fluorescent lamp 9...Reflector plate 91...Slit

Claims (1)

[Claims] 1. Move the document relatively in a direction substantially perpendicular to the main scanning direction of the optical line sensor, and irradiate light from a light source onto the surface of the document in order to have the image of the document sequentially read by the optical line sensor. In the document illumination device of the image reading device, the light source is covered with a reflective member so that the light emitted from the light source can be reflected inward, and a detection portion of the optical line sensor of the reflective member is provided. A slit having a predetermined width relative to the width of the optical line sensor is provided at a portion corresponding to the width of the optical line sensor in order to irradiate the light reflected by the reflecting member and the light emitted from the light source toward the document surface. Characteristic document illumination device of image reading device.