JP2002320071A - Luminaire and image reader provided with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminaire that eliminates unnecessary luminous flux to an original face so as to obtain a proper image and to provide an image reader provided with the device. SOLUTION: In the luminaire where light source units 104, 106 each comprising a plurality of point light sources are placed opposite to each other with a read line set in the main scanning direction of an original placing face 101 inbetween, the light source units 104, 106 placed with the read line inbetween are characterized in that they are placed at different heights. A shade member 107 is placed at an appropriate place at the read line side of at least either of the light source units. The shade member 107 is provided to the light source unit closer to the original face.

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 such as a copying machine or a facsimile apparatus, and more particularly to an illumination apparatus for the same.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing an illumination configuration when two original illumination lamps are used in an image reading apparatus such as a digital copying machine or a flatbed scanner, and is a sectional view in the sub-scanning direction. FIG.

In FIG. 4, reference numeral 101 denotes a document glass on which a document is placed. 102 is a mirror base on which a lamp is mounted. Reference numerals 1001 and 1002 denote document illumination lamps mounted on the mirror base 102. Original illumination lamp 1001, 1
Reference numeral 002 is opposed to the read line.

In the drawing, original illumination lamps 1001 and 1002
The trajectory of the light beam irradiated from the light source is shown by a solid line, a broken line, and a dashed line, and details thereof will be described below. The solid line is
The trajectory of a light beam directly emitted from the original illumination lamps 1001 and 1002 to the original surface is shown. The broken line indicates that the light beam reflected on the document surface is further reflected on the surface of the document illumination lamp 1002,
The trajectory again illuminates the read line. An alternate long and short dash line indicates a trajectory in which a light beam emitted from the original illumination lamp 1001 is reflected on the surface of the original illumination lamp 1002 and is emitted to a reading line on the original surface.

[0005] The trajectories of the three types of light beams are typical with reference to the original illumination lamp 1001, and in fact, there are reflected light beams described above for all the light beams emitted by the original illumination lamps 1001 and 1002. Original glass 101
Is irradiated with the total luminous flux including the above-mentioned reflected luminous flux, the reflected light is imaged on a photoelectric conversion element (not shown), and the original image is read.

[0006]

In the above-mentioned prior art, the multiple exposure of the document surface is performed by the multiple reflected light beams indicated by broken lines and dashed lines. Therefore, there is a problem that an error occurs between the document density and the reading level.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide an illuminating device capable of removing unnecessary light flux on a document surface and obtaining a proper image, and an image reading device including the illuminating device.

[0008]

According to the illuminating device of the present invention, a light source unit composed of a plurality of point light sources is opposed to each other with a reading line set in the main scanning direction of a document placing surface interposed therebetween. The apparatus is characterized in that the light source units arranged with the reading line interposed therebetween are arranged at different height positions.

Further, in the lighting device according to the present invention, a shielding member is provided at an appropriate position on a reading line side of at least one of the light source units.

Further, in the illumination device according to the present invention, the shielding member is provided on the light source unit on the side closer to the document surface.

Further, in the lighting device according to the present invention, the light source unit is constituted by a white light emitting diode.

Further, in the lighting device according to the present invention, the light source units are arranged at different angles with respect to the document surface.

Further, the image reading apparatus of the present invention has an image sensor unit including any one of the above-mentioned lighting devices, and a moving mechanism for performing a predetermined relative movement between a document to be read and the lighting device. The image of the document is read by relative movement between the image sensor unit and the document while illuminating the surface of the document with a device.

According to the present invention, typically, a plurality of light source units are provided with a reading line interposed therebetween, each of the light source units is arranged at a different height, and reading of a light source unit arranged at a position close to a document is performed. A shielding member is provided on the line side. Thus, the light beam can be emitted to the document surface at different angles, interference between the light source units can be prevented, and the amount of the multiple reflected light beams can be reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an illuminating device according to the present invention and an image reading device provided with the illuminating device will be described below with reference to the drawings. FIG. 1 is a sectional view of a lighting device according to the first embodiment of the present invention. The same components as those in the conventional example are denoted by the same reference numerals. In FIG. 1, 1
Reference numerals 03 and 105 denote LED substrates, which are arranged to face each other with the read line interposed therebetween. LED board 1
Reference numeral 05 is arranged at a position closer to the document surface than the LED substrate 103.

Reference numerals 104 and 106 denote LED substrates 10 respectively.
3 is an LED array mounted on 105. LED array 10
4 and 106 are constituted by white LEDs in this example. Reference numeral 107 denotes a shielding member mounted on the LED substrate 105. This shielding member 107 is an LED on the LED substrate 105
It is arranged on the substrate 103 side and acts so as to block a light beam emitted from the LED array 104 toward the LED 106.

In the above configuration, the LED arrays 104 and 10
The operation of the light beam illuminated on the reading line on the original surface will be described from 6.

The luminous flux directly emitted from the LED arrays 104 and 106 to the reading line is shown by a solid line. LED
The illuminating beam from row 104 is illuminated at angle a and the illuminating beam from LED row 106 is illuminated at angle b.

FIG. 2 shows a trajectory when the irradiation light beams from the LED arrays 104 and 106 are reflected on the document surface.
FIG. 2A shows a reflection trajectory of a light beam emitted from the LED array 104 to the reading line. Since the LED array 106 is arranged at a different height from the LED array 104, the light beam reflected on the document surface reaches the shielding member 107,
It does not interfere with the LED array 106.

On the other hand, FIG. 2B shows a reflection locus of a light beam emitted from the LED array 106 to the reading line. The light beam emitted at an angle b different from that of the LED array 104 and reflected on the document surface similarly does not interfere with the LED array 104.

FIG. 3 is a diagram showing the interference of the irradiation light beam between the LED arrays 104 and 106. FIG. 3A shows LE
The luminous flux trajectory from the D row 104 to the LED row 106 is shown. The light beam is blocked by the shielding member 107, and there is no direct interference from the LED array 104 to the LED array 106.

FIG. 3B shows a case where the LED array 106
The luminous flux trajectory to the column 104 is shown. Also in this case, the light beam is blocked by the shielding member 107, and there is no direct interference from the LED array 106 to the LED array 104.

As described above, the influence of the multiple reflection light beam due to the reflection on the document surface and the interference light beam between the LED arrays 104 and 106 among the light beams irradiated to the reading line on the document surface is reduced by the above-described configuration. In that case, the LED array 104,
The direct luminous flux irradiated from 106 becomes dominant.

In the above embodiment, the example in which the shielding member 107 is provided on the LED array 106 side has been described.
It is also possible to provide it on the D row 104 side. In that case, the shape of the shielding member 107 is devised so that the interference light flux between the LED arrays 104 and 106 does not occur. LED row 10
It is also possible to provide the shielding members 107 on both the fourth and fourth members.

[0025]

As described above, according to the present invention, in this type of illuminating device, unnecessary light flux to the reading line is reduced, and as a result, the error between the original density and the reading level is reduced. And a high-quality image can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a lighting device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a document surface reflection locus according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a trajectory of a direct interference light beam between LED arrays in the embodiment of the present invention.

FIG. 4 is a diagram showing an example using two original illumination lamps in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Original glass 102 Mirror stand 103, 105 LED board 104, 106 LED row 107 Shielding member 1001, 1002 Original illumination lamp

Claims (6)

[Claims] 1. An illumination device in which a light source unit including a plurality of point light sources is disposed opposite to each other with a reading line set in a main scanning direction of a document placing surface interposed therebetween. A lighting device, wherein the arranged light source units are arranged at different height positions. 2. The illuminating device according to claim 1, wherein a shielding member is provided at an appropriate position on a reading line side of at least one of the light source units. 3. The illumination device according to claim 2, wherein the shielding member is provided on a light source unit on a side closer to a document surface. 4. The lighting device according to claim 1, wherein the light source unit includes a white light emitting diode. 5. The lighting device according to claim 1, wherein the light source units are arranged at different angles with respect to a document surface. 6. An image sensor unit including the illumination device according to claim 1, and a moving mechanism for performing a predetermined relative movement between a document to be read and the image sensor unit. An image reading device, wherein an image of the document is read by relative movement between the image sensor unit and the document while illuminating the surface of the document with a lighting device.