JP2013162184A - Image reading apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reading apparatus with a light guide body capable of generating linear light with a narrower width.SOLUTION: In an image reading apparatus 1, a light guide body 10 includes the outer peripheral surface formed by combining a circular surface 31 and an elliptic arc surface 32, the center C of a circular arc and a first focus F1 of an elliptic arc match to each other, and a reflection part 33 is formed at a position including a second focus F2 of the elliptic arc.

Description

  The present invention relates to an image reading apparatus including a light guide that generates linear light from incident light and emits the light to a reading position of a document.

  In recent years, the image reading apparatus as described above has been used to digitize or copy originals such as documents. The outgoing linear light from the light guide provided in the image reading apparatus is reflected by the original on the original table. The reflected light from the document is guided to the line sensor via a mirror and a lens. The line sensor reads a document image for one line from incident light. Further, the image reading apparatus sequentially generates image information for one line while conveying the light guide in the sub-scanning direction using, for example, a slider, and thereby generates image information representing a document.

  As the light guide, there is a linear illumination device described in Patent Document 1 below. The linear illumination device includes a light guide having translucency, a light refraction / reflection region composed of a triangular wave surface on one side surface in the longitudinal direction of the light guide, and a longitudinal direction of the light guide. A light refracting / reflecting region provided on one side surface and light sources on both end surfaces of the light guide, the light refracting In this configuration, a diffusion surface is provided on the reflection region.

JP-A-11-134918

  As described above, in the image reading apparatus, since the line sensor reads a document for one line, the light guide need not irradiate linear light exceeding the width of one line (width in the sub-scanning direction). However, in the conventional linear illumination device, light is diffused on the diffusion surface that covers the reflection region, so that linear light that greatly exceeds the width of one line may be generated.

  Therefore, an object of the present invention is to provide an image reading apparatus provided with a light guide that can generate linear light having a narrower width.

  In order to achieve the above object, one embodiment of the present invention is an image reading apparatus which includes at least one light emitting element and a reflecting portion, and reflects incident light from the light emitting element by the reflecting portion. A light guide that generates linear light in the direction and emits the generated linear light toward the reading position of the document, and an imaging element that receives reflected light from the document and generates image information from the incident light. The light guide includes an outer peripheral surface obtained by combining an arc surface and an elliptic arc surface, the center of the arc and the first focal point of the elliptic arc coincide with each other, and the reflection portion includes the elliptic arc Is formed at a position including the second focal point.

  According to the image reading apparatus, it is possible to generate linear light having a narrower width.

1 is a schematic diagram illustrating a schematic configuration of an image reading apparatus according to an embodiment of the present invention. It is a perspective view of the periphery of the light guide of FIG. It is an enlarged view when the light guide body of FIG. 1 is planarly viewed from the main scanning direction. It is a figure which shows the positional relationship of the 1st focus of FIG. 3, a 2nd focus, and a reading position. It is a figure which shows the positional relationship of the focus position and reading position of the light guide of FIG. It is a figure which shows the positional relationship of the light emitting element of FIG. 2, and a light guide body end surface. It is a schematic diagram which shows the light guide which concerns on a 1st modification, and its periphery structure. It is a schematic diagram which shows the light guide which concerns on a 2nd modification, and its periphery structure.

  Hereinafter, each embodiment of the present invention will be described with reference to the accompanying drawings. In addition, in each drawing, the same code | symbol is attached | subjected regarding a corresponding member and part, and the overlapping description is abbreviate | omitted. In each figure, the X axis and the Y axis indicate the sub-scanning direction and the main scanning direction for image reading. The Z axis indicates the vertical direction of the image reading apparatus.

(Schematic configuration of image reading apparatus)
First, a schematic configuration of the image reading apparatus 1 will be described with reference to FIGS. 1 and 2. 1 and 2, the image reading apparatus 1 includes a light emitting element 9, a light guide 10, a reflective member 11, a glass platen 30, mirrors 22, 24, 25, and an imaging lens 26. And a line sensor 27 as an example of an image sensor.

  The light emitting element 9 is, for example, an LED, and emits light to the end surface S2 of the light guide 10, for example.

  The light guide 10 is made of a translucent material. Examples of the translucent material include acrylic, polycarbonate, and glass. The light guide 10 extends in the main scanning direction Y directly below the document table 30 and is arranged to be movable in the sub-scanning direction X. Incident light on the light guide 10 travels by repeating total internal reflection. This light is reflected by a reflecting portion (a reflecting portion 33 and a first reflecting portion 39 described later) formed in the light guide 10 to change the traveling direction. As a result, light having an incident angle smaller than the critical angle is incident on the inner and outer boundary surfaces of the light guide 10. As shown in FIG. 2, the incident light is emitted to the outside of the light guide 10, and is irradiated as a linear light L (see the alternate long and short dash line portion) to the document D obliquely above the light guide 10. The In the following description, a linear area irradiated with the linear light L in the document D is referred to as a reading area R.

  The reflected light from the document D on the document table 30 passes between the light guide 10 and the reflecting member 11 and is guided to the imaging lens 26 via the mirrors 22, 24, 25, and then the line sensor 27. Is received. The above optical paths are indicated by dotted arrows in FIG. The line sensor 27 generates image information corresponding to one line of the document D.

  The reflection member 11 is disposed on the opposite side of the light guide 10 with the optical path of the reflected light from the document D interposed therebetween. Incidentally, the linear light L is emitted from the light guide 10, but part of the light emitted from the light guide 10 to the reflecting member 11 is also present. The reflection member 11 reflects incident light toward the reading region R. As described above, by applying light to the reading region R from the side opposite to the linear light L, it is possible to reduce the influence of the shadow caused by the crease or the like of the document D.

  The light emitting element 9, the light guide 10, the reflecting member 11, and the mirror 22 are mounted on the first slider 21, and the mirrors 24 and 25 are mounted on the second slider 23. The first slider 21 moves immediately below the document table 30 in the sub-scanning direction X at a speed V, and the second slider 23 moves in the sub-scanning direction X at a speed V / 2. By moving in the sub-scanning direction X, the entire document D is scanned, the line sensor 27 sequentially generates image information for one line, and finally, image information representing the entire document is generated.

(Embodiment)
Hereinafter, the detail of the light guide 10 which concerns on embodiment of this invention is demonstrated.

  As shown in FIG. 2, the light guide 10 includes an outer peripheral surface S1 extending along the main scanning direction Y and two end surfaces S2 and S3 parallel to the ZX plane. Here, FIG. 3 is a plan view of the end surface S2 along the main scanning direction Y. FIG. As shown in FIG. 3, the outer peripheral surface S <b> 1 has a shape in which an arc surface 31 and an elliptical arc surface 32 are combined. More specifically, the arc center C constituting the arc surface 31 and the first focal point F1 of the ellipse arc constituting the ellipse arc surface 32 coincide with each other. The second focal point F2 of this elliptical arc is provided on the arc. The shape of the end surface S3 and the cross-sectional shape along the ZX plane of the outer peripheral surface S1 are the same as those of the end surface S2.

  In addition, a reflection portion 33 is provided along the arc surface 31 in a region including the second focal point F2. The reflection unit 33 is a reflection dot made of, for example, a prism or a white paint, and reflects incident light on itself.

  In addition, the light guide 10 is preferably disposed at a position where a line connecting the first focus F1 and the second focus F2 passes through the reading region R, as shown in FIG. Further, the light guide 10 is more preferably arranged at a position where the linear light L forms a focal point F on the reading region R, as shown in FIG.

  Moreover, the light emitting element 9 is arrange | positioned with respect to the light guide 10 at the following position. That is, the light emitting element 9 is aligned with the light guide 10 so that its own optical axis A passes through the first focal point F1 of the end surface S2 and is parallel to the main scanning direction Y.

(Operation and effect of the embodiment)
The light emitted from the light emitting element 9 enters the light guide 10 through the first focal point F1 of the end surface S2. Of the light in the light guide 10, the light hitting the elliptical arc surface 32 gathers at the second focal point F <b> 2 and its vicinity, that is, the reflecting portion 33 as indicated by an arrow a → b in FIG. Further, the light hitting the arc surface 31 passes through the first focal point F1 and hits the elliptical arc surface 32 as indicated by an arrow c → a in FIG. In this case as well, light gathers at the reflecting portion 33 as described above. As described above, the reflected light from the reflecting portion 33 is emitted as the linear light L to the outside of the light guide 10 and is applied to the reading region R of the document D.

  In the embodiment, by adopting the light guide 10 as described above, it becomes possible to collect incident light at the second focal point F2 (that is, the reflecting portion 33) with high efficiency. Therefore, according to the light guide 10, it is possible to generate the linear light L that is narrow in width and efficiently uses incident light. This prevents unnecessary light from entering the line sensor 27. As a result, it is possible to save power in the image reading apparatus 1 and to generate high-quality image information.

  Further, as shown in FIG. 6, the optical axis A is aligned with the first focal point F1. Further, as shown in FIG. 3, the reflection portion 33 is disposed on the arc surface 31, so that the reflected light on the arc surface 31 can be guided to the reflection portion 33. As shown in FIG. 4, the reading region R is preferably provided on a line connecting the first focus F1 and the second focus F2. With these configurations, incident light can be used more efficiently. Further, as shown in FIG. 5, the linear light L forms a focal point F on the reading region R, so that incident light can be used more efficiently.

(First modification)
Next, the light guide 10a according to the first modification will be described with reference to FIG. The light guide 10a includes an outer peripheral surface S4 extending along the main scanning direction Y and two end surfaces S5 and S6 parallel to the ZX plane. Further, the outer peripheral surface S4 has a shape obtained by combining another circular surface 35 in addition to the circular arc surface 31 and the elliptical arc surface 32 described above. In addition, the reflection part 33 is formed in the circular arc surface 31 similarly to the above-mentioned.

  The shape of the surface 35 is not particularly limited, but in the illustrated example, the surface 35 is an arc surface having a diameter smaller than the diameter of the arc surface 31. Further, the surface 35 is formed on the exit surface of the linear light L and functions as the light collecting means 35. The condensing means 35 condenses (refracts) the incident light and emits it as the linear light L when the reflected light of the reflecting portion 33 is incident. The condensing means 35 is preferably formed so that the linear light L has a focal point F on the reading region R. By providing the condensing means 35, it becomes possible to generate the linear light L having a narrow width while using the incident light of the light guide 10a more efficiently.

(Second modification)
Next, with reference to FIG. 8, the light guide 10b which concerns on a 2nd modification is demonstrated. The light guide 10b includes an outer peripheral surface S7 extending along the main scanning direction Y and two end surfaces S8 and S9 parallel to the ZX plane. Further, the outer peripheral surface S7 has a shape obtained by combining the circular arc surface 36, the first elliptical arc surface 37, and the second elliptical arc surface 38. More specifically, the arc center C of the arc surface 36, the first focal point F1 of the elliptical arc constituting the first elliptical arc surface 37, and the first focal point F3 of the elliptical arc constituting the second elliptical arc surface 38 coincide with each other. . The second focal point F2 of the elliptical arc constituting the first elliptical arc surface 37 is provided on the arc surface 36, and the second focal point F4 of the elliptical arc constituting the second elliptical arc surface 38 is the second focal point around the arc center C. It is provided at a position where F2 is rotated by a predetermined angle.

  Further, a first reflecting portion 39 is provided along the arc surface 36 in a region including the second focal point F <b> 2 on the arc surface 36. Similarly, the second reflecting portion 40 is provided along the circular arc surface 36 in the region including the second focal point F4. The 1st reflection part 39 and the 2nd reflection part 40 consist of reflective dots etc. similarly to the said reflection part 33, and reflect the incident light to self.

  Further, the light guide 10b is located at a position where a line connecting the first focus F1 and the second focus F2 passes through the reading region R, and a line connecting the first focus F3 and the second focus F4 passes through the reflecting member 11. Be placed.

(Operation and effect of the second modification)
Since the light guide body 10b has the same configuration as the light guide body 10, the same operations and effects as the above-described embodiment are achieved. In the light guide 10b, the light hitting the second elliptical arc surface 38 is reflected by the second reflecting portion 40 and is emitted as the second linear light L2 to the outside of the light guide 10b. The second linear light L2 is reflected by the reflecting member 11 and is applied to the reading region R of the document D. As described above, in the second modification, the light guide 10b employs a configuration capable of emitting the second linear light L2 to the reflecting member 11, so that the influence of the shadow caused by the crease of the document D or the like is affected. Further reduction is possible.

(Appendix)
In the above description, the number of the light emitting elements 9 is one (see FIG. 2). However, the present invention is not limited to this, and the number of light emitting elements 9 may be two or more. In the case of two, one light emitting element 9 is provided on each end face side of the light guide 10, for example.

  The image reading apparatus according to the present invention produces an effect that it is possible to generate narrower linear light, and is useful as a copying machine, a multifunction machine, various scanners, and the like.

DESCRIPTION OF SYMBOLS 1 Image reader 9 Light emitting element 10 10a 10b Light guide 31 36 Arc surface 32 Elliptical arc surface 33 Reflection part 35 Condensing means 37 1st elliptical arc surface 38 2nd elliptical arc surface 39 1st reflection part 40 2nd reflection part 11 Reflection member 27 Line sensor (imaging device)
L linear light L1 first linear light L2 second linear light

Claims (7)

At least one light emitting element;
A light guide that has a reflection part, generates linear light by reflecting incident light from the light emitting element by the reflection part, and emits the generated linear light toward the reading position of the document;
An image sensor that receives reflected light from the original and generates image information from the incident light;
With
The light guide includes an outer peripheral surface that combines an arc surface and an elliptical arc surface,
The center of the arc and the first focal point of the elliptical arc coincide with each other;
The reflecting portion is formed at a position including the second focal point of the elliptical arc.
Image reading device. The optical axis of the light emitting element is aligned so as to coincide with the first focal point,
The image reading apparatus according to claim 1. The second focal point is located on the arc, and the reflection portion is formed on the arc.
The image reading apparatus according to claim 1. The reading position is preset on a line connecting the first focus and the second focus,
The image reading apparatus according to claim 1. The focal length of the light guide is equal to the distance from the light guide to the document.
The image reading apparatus according to claim 1. Condensing means that is formed on the light guide, further collects the first linear light generated by the light guide, and emits the light toward the reading position.
The image reading apparatus according to claim 1, further comprising: At least one light emitting element;
First and second reflecting portions are provided, linear light is generated by reflecting incident light from the light emitting element by the first reflecting portion, and the generated linear light is emitted toward the reading position of the document. And a light guide that generates incident light from the light emitting element by reflecting the incident light from the light-emitting element at the second reflecting portion, and emits the generated second linear light toward the reflecting member; ,
A reflective member that is provided at a position opposite to the light guide across the optical path of the reflected light from the original and reflects the second linear light emitted from the light guide to irradiate the reading position When,
An image sensor that receives reflected light from the original and generates image information from the incident light;
With
The light guide includes an outer peripheral surface that combines an arc surface, a first elliptic arc surface, and a second elliptic arc surface,
The center of the arc and the first focal points of the first elliptic arc and the second elliptic arc coincide with each other,
The first reflecting portion and the second reflecting portion are formed at positions including a second focal point of the first elliptic arc and the second elliptic arc.
Image reading device.

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