JPH11317842A - Lighting device and image reader using the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow even a lighting device for reading optical system small in working distance where no opposed reflecting plate cannot be placed to make lighting in two directions. SOLUTION: In this lighting device 3, one end face 6a of a light guide 6 is placed nearly to a side of a light source 5 emitting light to an image side of an original and not opposite to an image side of the original, and other end face 6b of the light guide 6 is directed to a position of the image side onto which the light source 5 emits light. The light of the light source 5 not directed to the image side is emitted from the end face 6a and the light propagates in the light guide 6, is emitted from another end face 6b to light the image side. Thus, the luminous quantity to light the image side is increased and the image side is lighted from two directions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device for illuminating an image surface of a document and an image reading device using the illuminating device.

[0002]

2. Description of the Related Art Conventionally, some illuminating devices are provided with opposed reflectors for illuminating the image surface of a document from two directions with one light source. As a conventional example of such an illuminating device and an image reading device using the illuminating device, there are an illuminating position aligning device, a document scanner and a copying machine described in Japanese Patent Application Laid-Open No. 8-237430.

The opposing reflector reflects the light emitted from the light source and not directed to the image surface, and makes the light incident on the image surface of the original. Therefore, light from two directions, that is, light that is directly incident from the light source and light that is reflected by the opposing reflector, is incident on the image surface of the document.

[0004]

SUMMARY OF THE INVENTION Conventional Japanese Patent Laid-Open No. 8-23
In the illumination alignment apparatus, document scanner, and copier described in Japanese Patent No. 7430, light from the light source is reflected by the opposing reflector, so that another member cannot be disposed between the light source and the opposing reflector. For this reason, a document such as a reading optical system in which the distance from the image surface of the document to the lens is not sufficiently long or a 1: 1 optical system used in a contact image sensor in which a contact glass and a lens are arranged close to each other. In a reading optical system having a small distance from the image surface to the lens, that is, a working distance, it is impossible to use the opposing reflecting plate.

It is an object of the present invention to enable illumination from two directions even in a reading optical system illumination device having a small working distance.

Another object of the present invention is to eliminate restrictions on the arrangement of each member constituting the lighting device.

Another object of the present invention is to effectively utilize the light amount of a light source that is not used.

[0008]

According to a first aspect of the present invention, there is provided an illumination device, comprising: a light source for irradiating an image surface of a document with light; one end surface being arranged close to the light source and the other end surface facing the image surface. A light guide that guides light emitted from the light source and not incident on the image surface from one end surface to the other end surface and emits the light to a position on the image surface directly illuminated by the light source.

Therefore, the amount of light illuminating the image surface of the document increases, and the image surface can be illuminated from two directions.

According to a second aspect of the present invention, in the lighting device according to the first aspect, the light guide is an optical fiber array.

Therefore, the loss of the amount of light at the bent portion of the light guide is small.

According to a third aspect of the present invention, there is provided the lighting device according to the first or second aspect, wherein a light diffusing plate is provided on an end face of the light guide that faces the image surface of the document.

Accordingly, the light emitted from the light guide is diffused, and the image plane can be uniformly illuminated.

According to a fourth aspect of the present invention, there is provided the illuminating device according to the first, second or third aspect, wherein the light source is of a phosphor light emitting type, and the first region facing the image surface of the document and the light guide. An opening in which the phosphor is not applied is formed in a second region facing one end face of the first substrate.

Therefore, the light emitted from the phosphor is directly emitted from the openings formed in the respective regions. Therefore, the amount of light in the required direction can be efficiently increased.

The invention according to claim 5 is the invention according to claims 1, 2, 3
Or the lighting device according to 4, wherein the area ratio of the openings formed in the first and second regions of the light source where the phosphor is not applied directly reaches the image surface of the document from the first region. The light amount and the light amount reaching the image surface from the second region via the light guide are set to be substantially equal.

Accordingly, the amounts of light in the two directions illuminating the image plane are substantially equal.

According to a sixth aspect of the present invention, there is provided an image reading apparatus comprising: a lighting device according to the first, second, third, fourth or fifth aspect; a contact glass on which an original is placed; A double-magnification element, a single-magnification sensor that forms an image of reflected light from the image surface of the document condensed by the single-magnification imaging element,
The lighting device includes a support member that positions and supports the illumination device, the contact glass, the equal-magnification imaging element, and the equal-magnification sensor.

Therefore, even in an image reading apparatus in which the work distance is so small that the opposing reflecting plate cannot be used, the image surface of the document can be illuminated from two directions.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of an illumination device of the present invention and an image reading device using the same will be described with reference to FIGS. The image reading device 1 includes a contact glass 2 on which a document is placed with an image surface facing down,
Illumination device 3 for illuminating the image surface via contact glass 2
And an image scanner unit 4 for reading light reflected from the image surface.

The illumination device 3 includes a light source 5 and a light guide 6. As the light source 5, a fluorescent lamp, a xenon tube, or
A cold cathode fluorescent tube or the like is used. The light guide 6 is formed of a transparent refractive index member. Examples of the transparent refractive index member include acrylic resin and polycarbonate (P
C) and the like.

The light guide 6 has one end face 6 a arranged close to the side of the light source 5 not facing the contact glass 2, and the other end face 6 b arranged close to the contact glass 2. It is arranged so as to rotate. Light emitted from the side of the light source 5 not facing the contact glass 2 enters the end face 6a, propagates while being totally reflected at the interface, and exits from the end face 6b. Hereinafter, for convenience, the end face 6a is referred to as an incident end face 6a, and the end face 6b is referred to as an output end face 6b. Here, the light source 5 and the emission end face 6b are arranged so as to illuminate the image plane from different directions.

Due to such an arrangement, it is unavoidable that the light guide 6 is bent at several places, so that a small amount of light loss occurs at the bent part. Set the optimal shape with the tool and minimize it.

The image scanner unit 4 includes a unit-magnification imaging element 7.
And an optical path separating mirror 9 for directing the light condensed by the equal-magnification imaging element 7 toward the equal-magnification sensor 8. The unit-magnification imaging element 7 is arranged so as to face the original document with the contact glass 2 interposed therebetween, and has a roof mirror array 10, an aperture plate 11, a lens array 12, and a hood 13 sequentially stacked.

Then, the contact glass 2 and the light guide 6
End portions including the end surfaces 6a and 6b of the
, The equal-magnification sensor 8 and the optical path separating mirror 9 are supported by a frame 14 as a support member and fixed at respective predetermined positions. The frame 14 is formed by integrally molding a resin material or by extruding aluminum.

In such a configuration, the contact glass 2
An image surface of a document (not shown) placed on the light guide 5 is illuminated by direct light from the light source 5 and light from the emission end face 6 b of the light guide 6. The light reflected from the image surface is transmitted to the same-magnification imaging element 7.
And is reflected by the optical path separating mirror 9 to form an image on the equal-magnification sensor 8. The image reading apparatus 1 reads an image of a document as digital information line by line, and reads the entire image of the document by moving in a direction orthogonal to the main scanning direction.

According to this embodiment, the image side of the original is
Since the light emitted from the light source 5 and the light emitted from the side not facing the image surface of the light source 5 and guided by the light guide 6 illuminates, the light emitted from the light source 5 and not directly illuminating the image surface is effective. And the amount of light illuminating the image plane can be increased. Further, since the image surface is illuminated from two directions, there is an effect of reducing shadows generated around the pasted portion when the image surface has the pasted portion.

In this embodiment, the light guide 6 is formed of a transparent member. However, in practice, a light guide tube having a hollow structure having an inner surface as a reflection surface may be used. A light guide on which a high reflectivity member is applied or deposited may be used. Here, in the case of the latter light guide, light transmission with higher efficiency is possible as compared with the light guide 6 of the present embodiment. Further, in this case, as the light guide 6, the loss of light amount at the bent portion is further suppressed, and light transmission with higher efficiency is possible. Optical fiber arrays include glass fibers and resin fibers.

Furthermore, in implementing the present embodiment, as shown in FIG. 2, a gradient-index condensing lens array may be used as the unit-magnification imaging element 7. In this case, the equal-magnification sensor 8 is arranged to face the contact glass 2 via the equal-magnification imaging element 7.

Next, a second embodiment of the illumination device of the present invention and an image reading device using the same will be described with reference to FIG. The same parts as those described in the first embodiment are denoted by the same reference numerals, and detailed description is omitted (the same applies to the following embodiments). In the present embodiment, the light diffusing plate 15 is provided on the emission end face 6 b of the light guide 6.

Light incident from the incident end face 6a of the light guide 6 propagates inside the light guide 6 by internal reflection, and therefore has directivity when emitted from the output end face 6b. Therefore, as in the present embodiment, the light diffusing plate 1 is
When the light source 5 is provided, the light is emitted as a secondary light source, so that the image surface of the document can be uniformly illuminated. Further, since a light beam spread in the reading sub-scanning direction can be obtained, even if there is a positional shift of the unity-magnification sensor 8 in the sub-scanning direction, the fluctuation of the illumination distribution is reduced, and a more stable illumination light amount can be obtained.

In implementing the present embodiment,
As in the previous embodiment, a fluorescent lamp, a xenon tube, a cold cathode fluorescent tube, or the like is used as the light source 5, and the light guide 6 is a light guide formed only of a transparent refractive index member. Without, a light guide tube having a hollow structure in which the inner surface is a reflective surface, or a light guide in which a high reflectivity member is applied or deposited on the outer peripheral surface of a transparent member,
Alternatively, an optical fiber array may be used. Further, a gradient index condensing lens array may be used as the 1 × image forming element 7.

Next, a third embodiment of the illumination device of the present invention and an image reading device using the same will be described with reference to FIGS.
It will be described based on. In the present embodiment, the light source 5 is such that a fluorescent substance 16 is applied to the inner wall of the tube, and openings 16a and 16b are formed at predetermined positions of the fluorescent substance 16.

The first opening 16a is provided at a position opposed to the image surface of the document, and emits light toward the image surface from this opening 16a. The second opening 16 b faces the incident end face 6 a of the light guide 6.

In such a configuration, the light emitted from the phosphor 16 applied to the inner wall of the tube is transmitted to the openings 16a and 16b.
Emitted from Here, the ratio of the amount of light from the front side of the phosphor 16 to the amount of light from the back side is about 9: 1. Therefore, by providing the openings 16a and 16b, the amount of light in the required direction can be efficiently increased.

As shown in FIG. 5, the amount of light that reaches the image surface of the original is the same as that of the light A from the opening 16a.
Light B emitted from the light guide 6b and propagated through the light guide 6 is also proportional to the area of the openings 16a and 16b, respectively. Also,
The inclination of the graph of the light B is smaller than that of the light A due to the loss when the light B propagates in the light guide 6.

When the light amounts of the light A and the light B are set to be equal, the area of the opening 16b is set to be larger than the area of the opening 16a according to the graph of FIG. In this case, the image surface can be illuminated with light from two directions having the same light amount.

In the present embodiment, the same-magnification imaging element 7 is used.
FIG. 4 shows a refractive index distribution type condensing lens array as an example. In implementation, the same-magnification imaging element 7 in which a roof mirror array 10, an aperture plate 11, a lens array 12, and a hood 13 are sequentially superimposed is provided. It may be used.

In implementing this embodiment,
As in the previous embodiment, the light guide 6 is not only a light guide formed of a transparent refractive index member, but also a light guide tube having a hollow structure in which the inner surface is a reflection surface, and a light guide formed on the outer surface of the transparent member. It may be a light guide on which a reflectance member is applied or deposited, or an optical fiber array.

[0040]

According to the first aspect of the present invention, the light source for irradiating the image surface of the document with light, one end surface is arranged close to the light source and the other end surface is arranged toward the image surface, and the light is emitted from the light source. A light guide that guides light that does not enter the image surface from one end surface to the other end surface and emits the light to a position directly illuminated by the light source on the image surface, so that an amount of light that does not directly illuminate the image surface of the light source is effective. By utilizing this, the amount of light illuminating the image surface of the document can be increased, and the image surface can be illuminated from two directions.

According to the second aspect of the present invention, since the light guide is an optical fiber array, the loss of the amount of light at the bent portion of the light guide can be reduced.

According to the third aspect of the present invention, since the light diffusing plate is provided on the end face of the light guide which is located toward the image surface of the original, the light having directivity propagating through the light guide is provided. Since the light can be diffused and emitted, the image surface can be uniformly illuminated.

According to the fourth aspect of the present invention, the light source is of a phosphor light emitting type, and the first area facing the image surface of the document and the second area facing one end face of the light guide have: Since the openings to which the phosphor is not applied are formed, the light emitted by the phosphor is directly emitted from the openings formed in the respective regions, so that the amount of light in the required direction can be increased and the illumination can be performed efficiently.

According to the fifth aspect of the present invention, the ratio of the area of the openings formed in the first and second regions of the light source where the phosphor is not applied is such that the first region directly reaches the image surface of the original from the first region. Since the amount of light to be transmitted and the amount of light that reaches the image surface from the second region via the light guide are set to be substantially equal,
The amounts of light in the two directions illuminating the image plane can be made substantially equal.

According to the sixth aspect of the present invention, there is provided the first, second, and third aspects.
The illumination device according to 3, 4 or 5, a contact glass on which the original is placed, a 1 × image forming element arranged close to the contact glass, and an image plane of the original condensed by the 1 × imaging element. 1x sensor that forms an image of the reflected light, and a support member that positions and supports the illuminating device, the contact glass, the 1x imaging element, and the 1x sensor, so that the opposing reflector cannot be used. Even in an image reading apparatus having a small work distance, the image surface of the document can be illuminated from two directions.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment of an illumination device of the present invention and an image reading device using the same.

FIG. 2 is a schematic diagram showing a modification of the first embodiment.

FIG. 3 is a schematic diagram showing a lighting device according to a second embodiment of the present invention and an image reading device using the same.

FIG. 4 is a schematic diagram showing a third embodiment of the illumination device of the present invention and an image reading device using the same.

FIG. 5 is a graph showing the relationship between the width of each opening and the amount of light reaching the image surface of a document.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Contact glass 3 Illumination apparatus 5 Light source 6 Light guide 7 1: 1 imaging element 8 1: 1 sensor 14 Support member 15 Light diffusing plate 16 Phosphor 16a, 16b Opening

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroyuki Inoue Ricoh Company, Ltd. 1-3-6 Nakamagome, Ota-ku, Tokyo

Claims (6)

[Claims] A light source for irradiating light to an image surface of a document; and a light source, one end surface of which is arranged close to the light source and the other end surface of which is arranged facing the image surface. A light guide that guides the light from one end face to the other end face and emits the light to a position directly illuminated by a light source on the image plane,
A lighting device comprising: 2. The lighting device according to claim 1, wherein the light guide is an optical fiber array. 3. The illuminating device according to claim 1, wherein a light diffusing plate is provided on an end surface of the light guide, which is arranged toward an image surface of the document and emits light. 4. The light source is a phosphor light emitting type, and a phosphor is applied to a first region facing an image surface of a document and a second region facing one end surface of the light guide. The lighting device according to claim 1, wherein the lighting device has no opening. 5. An area ratio of an opening formed on the first and second regions of the light source, on which the phosphor is not applied, is determined by a light amount directly reaching the image surface of the document from the first region and a second light amount. 5. The lighting device according to claim 4, wherein the light amount reaching the image surface via the light guide from the region is set to be substantially equal. 6. A lighting device according to claim 1, 2, 3, 4 or 5, a contact glass on which a document is placed, a 1 × image forming element arranged close to the contact glass, and a 1 × image element. A 1 × sensor that forms an image of reflected light from the image surface of the original document condensed by the scanner; and a support member that positions and supports the illumination device, the contact glass, the 1 × imaging element, and the 1 × sensor. Image reading device provided.