JP2011004289A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image reader efficiently and evenly irradiating an object to be read with light from both sides of a sub-scanning direction.SOLUTION: The image reader irradiates a document D with light emitted from a plurality of light emitting elements 11 and 12 which are arranged side by side in a main-scanning direction A, and optically reads the reflected light. A top-view LED 11 which emits light in a first direction (upward) and a side-view LED 12 which emits light in a second direction (laterally) are arranged on a single substrate 20. Further, a photoconductor 30 is installed, which receives the light emitted from the LEDs 11 and 12 and guides the light so as to irradiate the document D on a platen glass 40 from both sides of the sub-scanning direction B.

Description

  The present invention relates to an image reading apparatus, and more particularly to an image reading apparatus that optically reads reflected light from a document image.

  In general, an image reading apparatus called a scanner includes a reading system including a light source arranged one-dimensionally in a main scanning direction and a reading object such as a document in a sub-scanning direction orthogonal to the main scanning direction. The image is read two-dimensionally. Conventionally, many fluorescent lamps have been used as this type of light source, but in recent years, the use of LEDs has been studied. However, unlike a fluorescent lamp, an LED is a point light source. Therefore, in order to obtain a one-dimensional (line-shaped) light distribution necessary for scanning, the LED is changed to a line shape using a light guide. Alternatively, it is necessary to form a plurality of lines in a one-dimensional direction on the substrate.

  In addition, in an image reading apparatus, in order to read a three-dimensional portion without shading, it is required to irradiate the reading target from both sides in the scanning direction (sub-scanning direction). In conventional illumination systems using fluorescent lamps, instead of illuminating from both sides using two fluorescent lamps, a single fluorescent lamp and a reflecting mirror facing the fluorescent lamp are used for cost reduction. However, when an LED is used as a light source, the LED has a strong directivity, so that it cannot be used with a wide opening angle like a fluorescent lamp, and it is difficult to irradiate light from both sides in the scanning direction.

  Therefore, Patent Document 1 proposes to arrange LEDs on both sides in the scanning direction and irradiate the reading object from both sides. Patent Document 2 proposes that light from LEDs arranged at both ends in the main scanning direction is guided in the main scanning direction by a light guide and irradiated from both sides in the scanning direction.

  However, disposing LEDs on both sides as in the former inevitably increases the cost because the required substrate becomes larger and wiring becomes complicated. In the latter configuration, in which the light is guided in the main scanning direction by the light guide, the light guide distance becomes long, so that the attenuation of the light becomes large, the light amount becomes uneven, and the necessary light amount cannot be obtained. Has a point.

JP 2004-170858 A JP 2002-185708 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus capable of efficiently and evenly irradiating light on a reading object from both sides in the sub-scanning direction.

In order to achieve the above object, an image reading apparatus according to an aspect of the present invention is provided.
In an image reading apparatus that irradiates a reading object with light emitted from a plurality of light emitting elements juxtaposed in the main scanning direction and optically reads the reflected light,
A first light emitting element that emits light in a first direction;
A second light emitting element that emits light in a second direction that is 90 ° different from the first direction;
A single substrate holding the first and second light emitting elements;
A light guide that receives light emitted from the first and second light-emitting elements and guides the object to be read from both sides in the sub-scanning direction;
It is provided with.

  According to the present invention, the light to be read is irradiated from both sides in the sub-scanning direction (scan direction) through the light guide body with the light emitted from the first light-emitting element and the second light-emitting element in directions different by 90 °. Therefore, it is possible to efficiently irradiate the object to be read from both sides, and it is possible to read without making a shadow even in a three-dimensional part. In addition, since the first and second light-emitting elements are arranged on a single substrate, wiring and the like are simplified, and cost can be reduced.

1 is a schematic configuration diagram illustrating an image reading apparatus according to a first embodiment. It is a perspective view which shows the said image reading apparatus. It is a top view which shows the said image reading apparatus. It is a perspective view which shows the light guide of the said image reading apparatus. It is a top view which shows the image reading apparatus which is 2nd Example.

  Embodiments of an image reading apparatus according to the present invention will be described below with reference to the accompanying drawings. In addition, in each drawing, the same code | symbol is attached | subjected regarding the same member and part, and the overlapping description is abbreviate | omitted.

(See the first embodiment, FIGS.
As shown in FIGS. 1 and 2, the image reading apparatus according to the first embodiment has a plurality of first and second LEDs (light emitting diodes) 11 and 12 on the upper surface of a single substrate 20 in the main scanning direction. A light guide 30 is disposed between the LEDs 11 and 12 and the reading position C in juxtaposition with A. The first LED 11 is a top surface illumination (top view) type, and the second LED 12 is a side surface illumination (side view) type. Three second LEDs 12 are arranged at both ends of the substrate 20, and a plurality of the first LEDs 11 are arranged at equal intervals between the second LEDs 12.

  The light B1 emitted upward from the first LED 11 is deflected / condensed by the light guide 30 and irradiates the document D placed on the platen glass 40 from the lower left direction in FIG. The light B2 emitted from the second LED 12 is reflected / diffused by a plurality of fine protrusions provided in the main scanning direction A on the boundary surface 31 of the light guide 30 and travels in the main scanning direction A, as shown in FIG. The document D is irradiated from the lower right direction. A region where the minute protrusion is formed is hatched in each drawing and indicated by reference numeral 32.

  The substrate 20 is installed in parallel with the platen glass 40 and has a length that sufficiently covers the width of the document D in the main scanning direction A in which the LEDs 11 and 12 are arranged. Further, the LEDs 11 and 12 are used in such a number that the light quantity necessary for optically reading the document image can be obtained. The light radiated from the LEDs 11 and 12 and reflected by the document D is reflected by the mirror 45, read by the image sensor 47 such as a CCD through the imaging lens 46, and processed as image information. At the time of reading, the illumination system including the LEDs 11 and 12 moves in the sub-scanning direction B at a predetermined speed.

  In the first embodiment, the light D emitted from the first LED 11 and the second LED 12 in different directions (upward and side directions) of 90 ° is interposed between the light guides 30 so that the document D is obtained. Irradiation can be performed efficiently from both sides in the sub-scanning direction B, and an image can be read without creating a shadow even if there is a step on the document D at the reading position C. In addition, since the first and second LEDs 11 and 12 are disposed on the single substrate 20, wiring and the like are simplified, and the cost can be reduced. Furthermore, by using the light guide 30 having the light guide function and the light collection function, the light emitted from the LEDs 11 and 12 can be condensed at the reading position C, and the light use efficiency can be increased.

  Further, since the LEDs 11 and 12 are point light sources, unevenness in the amount of light tends to occur in the arrangement direction. However, by using the light guide 30, light diffusion occurs and unevenness in the amount of light in the main scanning direction A is reduced. In particular, since the light emitted from the second LED 12 is diffused in the main scanning direction A by the minute protrusions provided in the region 32, unevenness in the amount of light in the main scanning direction A is satisfactorily eliminated. Further, since the light emitted from the first LED 11 irradiates the original D almost directly, there is no shortage of light.

  Further, since the light is diffused by the light guide 30, the difference in color between the LEDs 11 and 12 is also reduced, and the difference in color (color unevenness) at each specific position in the main scanning direction A is reduced. . Moreover, by selecting the ratio of the number of the first LEDs 11 and the second LEDs 12 arranged, the irradiation ratio from the left and right sides can be freely set, and the ideal left / right balance can be brought close to 1: 1. it can.

(Refer to the second embodiment, FIG. 5)
The image reading apparatus according to the second embodiment basically has the same configuration as that of the first embodiment. As shown in FIG. 5, as shown in FIG. The light reflecting sheet 35 is disposed on the outer peripheral surface of the light guide 30 (excluding the light emitting portion). A light diffusing sheet may be arranged in place of the light reflecting sheet 35.

  In the second embodiment, the light emitted from the first LED 11 irradiates the document D through the light guide 30 as in the first embodiment. On the other hand, much of the light emitted from the second LED 12 is reflected / diffused by the minute protrusions provided in the region 32 to irradiate the document D, as in the first embodiment. The light that has not been reflected by the minute protrusions in the region 32 and the light that has been reflected by the surface of the light guide 30 or the light reflecting sheet 35 are reflected / diffused by the minute protrusions provided in the region 33 of the other boundary surface. The original D is irradiated after being reflected / diffused by the minute protrusions in the region 32.

(Other examples)
The image reading apparatus according to the present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the gist thereof.

  In particular, the shape and arrangement of the light guide are arbitrary. The position of the image reading device and the platen glass may be fixed, and the image may be read while conveying the document in the sub-scanning direction at a predetermined speed. Further, instead of the top-illuminated LED, a top-illuminated organic EL (electroluminescence) element may be arranged in the main scanning direction.

  As described above, the present invention is useful for an image reading apparatus, and is particularly excellent in that light can be efficiently and evenly applied to a reading object from both sides in the sub-scanning direction.

11,12 ... LED
DESCRIPTION OF SYMBOLS 20 ... Board | substrate 30 ... Light guide 32, 33 ... Minute protrusion formation area 35 ... Light reflection sheet 40 ... Platen glass A ... Main scanning direction B ... Sub-scanning direction D ... Original

Claims (6)

In an image reading apparatus that irradiates a reading object with light emitted from a plurality of light emitting elements juxtaposed in the main scanning direction and optically reads the reflected light,
A first light emitting element that emits light in a first direction;
A second light emitting element that emits light in a second direction that is 90 ° different from the first direction;
A single substrate holding the first and second light emitting elements;
A light guide that receives the light emitted from the first and second light emitting elements and guides the object to be read from both sides in the sub-scanning direction;
An image reading apparatus comprising:   2. The image reading apparatus according to claim 1, wherein the first and second light emitting elements are LEDs.   The image reading apparatus according to claim 1, wherein one of the first and second light emitting elements is an organic EL element.   The first light-emitting element is a top-illuminated type, the second light-emitting element is a side-illuminated type, the second light-emitting element is disposed at both ends of the substrate, and the first light-emitting element is a second light-emitting element. The image reading device according to claim 1, wherein the image reading device is disposed between the two.   5. The image reading apparatus according to claim 1, wherein a light reflecting member or a light diffusing member is disposed on an outer peripheral surface of the light guide body.   6. The image reading apparatus according to claim 1, wherein the light guide has a plurality of minute protrusions provided in a main scanning direction.

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