WO2008013234A1

WO2008013234A1 - Linear illuminating apparatus, image sensor and image reader using the image sensor

Info

Publication number: WO2008013234A1
Application number: PCT/JP2007/064698
Authority: WO
Inventors: Masayuki Katsumata; Shuuichi Shimoda; Azusa Shiratori
Original assignee: Canon Components, Inc.
Priority date: 2006-07-27
Filing date: 2007-07-26
Publication date: 2008-01-31
Also published as: JPWO2008013234A1; TW200822695A

Abstract

Provided is a linear illuminating apparatus which permits light emitted from a light emitting element to efficiently enter a light guide body. An image sensor using such linear illuminating apparatus, and an image reader are also provided. The linear illuminating apparatus is provided with the light emitting element; the long light guide body, which receives the light emitted from the light emitting element at an end surface, guides the received light in the longitudinal direction and outputs the light from an outputting surface; and a light guide body cover, which covers the light guide body, has an opening section for passing through the light emitted from the outputting surface of the light guide body and fits in the light emitting element over the end surface of the light guide body.

Description

Specification

Technical field of line illumination device, image sensor and image reading device using the same

The present invention relates to a line illumination device used in an image sensor or the like that irradiates a document reading surface and reads reflected light, an image sensor, and an image reading device using the same.

Background art

Conventionally, there are various types of image sensors used in image reading apparatuses such as image scanners, facsimiles, and copying machines, such as a reduction type and a contact type. Among them, the contact image sensor (hereinafter referred to as CIS) is composed of an illumination device, a unity imaging optical device, a photoelectric conversion element, and the like. In general, this CIS has a short optical path length compared to an image sensor using a reduction optical system, so that it is easy to downsize the device! For this reason, it can be easily incorporated into equipment, and instead of a reduction optical system, it has come to be used in many thin flatbed image readers. The line-shaped illuminator used in this CIS illuminates the original surface with a required illuminance or higher and the reflected light from the original is required to reach a photoelectric conversion element with a sufficient amount of light. The

FIG. 9 is a structural cross-sectional view of a conventional contact image sensor. Here, the case where there are only one light guide 42 is shown. This close-contact image sensor has a line-shaped illumination device for irradiating a document, and receives reflected light from the document 49 through a lens 44 by a line sensor 45 formed by a photoelectric conversion element and converts it into an electrical signal. is doing.

In FIG. 9, reference numeral 43 denotes a frame that supports the constituent members, 44 denotes a lens array that forms an optical image of the original on the line sensor 45, and 45 denotes a light receiving unit that photoelectrically converts the optical image of the original into an electrical signal. It is a line sensor arranged in a plurality of lines. 46 is a sensor board on which a line sensor 45 is mounted. 41r, 41g, and 41b are light emitting elements 41 that are light emitting diodes (hereinafter referred to as LEDs) for illuminating the document, and are disposed on the end face of the light guide 42 that extends in the longitudinal direction. The line-shaped illuminator takes in the light emitted from the LED, and the light guide is designed so that the amount of illumination light is approximately uniform over the length of one line of the document reader. have. 47 is a connector for connecting a sensor signal and an external device, and 48 is a document support table made of transparent glass for supporting a document 49.

[0005] In general, light emitted from a light emitting element disposed on the end face of the light guide 42 is guided into the acrylic light guide 42, and the inside is complicatedly reflected to the outside from the emission surface. The original 49 is emitted and illuminated.

[0006] As such a line-shaped illumination device, various shapes are used, and recently, a prismatic shape as shown in FIG. 10 is also used (Patent Document 1).

FIG. 10 is a diagram showing a configuration of a conventional line illumination device.

The light guide 20 of the line illumination device 10 is configured to be inserted into a light guide attachment frame 31 integrally formed with the LED light source unit 30. Further, the light guide 20 is provided with a light guide cover (not shown) on the outer side.

Patent Document 1: Japanese Patent Laid-Open No. 2005-236940

Disclosure of the invention

Problems to be solved by the invention

[0008] However, in the configuration of FIG. 10, the configuration of the LED light source unit 30 is complicated, and a custom-made LED is required rather than a commercially available LED. Further, depending on the shape of the light guide, the light guide mounting frame 31 needs to be enlarged, and accordingly, the shape of the LED light source unit 30 needs to be enlarged.

[0009] An object of the present invention is to solve the above-mentioned problems of the prior art.

[0010] Further, the present invention is characterized in that the light emitting element and the light guide are covered with the same light guide cover, and the line illumination that allows the emitted light from the light emitting element to enter the light guide efficiently. To provide an apparatus.

[0011] Another object of the present invention is to provide an image sensor and an image reading device using the line illumination device.

Means for solving the problem

[0012] In order to achieve the above object, a line illumination device according to one aspect of the present invention has the following configuration. That is,

A light emitting element; A long light guide that receives light emitted from the light emitting element from an end surface, guides the received light in a longitudinal direction, and emits light from an emission surface;

A light guide that covers the light guide and has an opening for allowing light emitted from the exit surface of the light guide to pass therethrough, and that fits the light emitting element beyond the end face of the light guide. Body cover,

It is characterized by having.

The invention's effect

[0013] The present invention has the following effects.

(1) Since the light emitting element and the light guide are covered with the same light guide cover, the emitted light from the light emitting element can be efficiently incident on the light guide.

(2) A complicated structure for preventing light leakage considering the fitting of the light guide on the light emitting element side becomes unnecessary.

(3) The light emitting element and the light guide can be easily positioned.

Brief Description of Drawings

FIG. 1 is a perspective view schematically showing a line illumination device 100 according to Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view taken along spring I I in FIG.

FIG. 3 is a cross-sectional view of the light guide of the line illumination device according to the present embodiment.

FIG. 4 is an enlarged cross-sectional view of the vicinity of a light emitting element in the line illumination device according to Embodiment 1 of the present invention.

FIG. 5 is an enlarged view of the vicinity of a light emitting element in a line illumination device according to Embodiment 2 of the present invention.

FIG. 6 is a perspective view schematically showing a contact image sensor using the line illumination device according to the present embodiment.

7 is a cross-sectional view taken along line II II in FIG.

FIG. 8 is an external perspective view of a flatbed image scanner using a contact image sensor equipped with a line illumination device according to an embodiment of the present invention.

FIG. 9 is a structural sectional view of a conventional contact image sensor. FIG. 10 is a diagram showing a configuration of a conventional line illumination device.

FIG. 11 is a partially enlarged cross-sectional view of a comparative line illumination device in which the line illumination device according to the first embodiment is provided as a comparison frame corresponding to the light guide attachment frame shown in FIG. Explanation of symbols

[0015] 100 line lighting device

101 Light-emitting element

102 substrates

103 Light guide cover

104 Air layer

105 Photosensitive end face (end face)

106 Light guide

108 Light exit

110 Extension

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the present invention according to the claims, and all combinations of features described in the present embodiments are essential to the solution means of the present invention. Is not limited.

[0017] [Embodiment 1]

FIG. 1 is a perspective view schematically showing line illumination device 100 according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view taken along spring I I in FIG.

[0018] The light emitting element 101 according to the present embodiment uses a commercially available white LED (model number manufactured by Nichia Corporation; NFSW036B). The LED package has a thickness of 0.8 mm and a height and width of 3.5 mm. The LED is disposed on a copper substrate 102 having a thickness of 2 mm for heat dissipation.

Note that the light emitting element (light source) 101 may be formed of a plurality of chips by connecting a large number of LEDs having normal brightness. Instead of white LEDs, it is also possible to use three types of red, blue, and green LEDs. In the present embodiment, the light guide 106 is formed by forming an acrylic resin having a high light transmittance into a predetermined shape. The light guide cover 103 was formed by molding a polycarbonate resin in which a white pigment was kneaded. The length of the light guide 106 is usually about 230 mm in an application for irradiating an A4 size document. Its cross-sectional shape is a fan of about 30 square mm (see Fig. 3), and it has a long bar shape as a whole.

Reference numeral 103 denotes a light guide cover that covers the light guide 106, and includes the light emitting element 101. Here, the light guide cover 103 has an extension 110 that covers the air layer 104 between the light emitting element 101 and the light guide 106 and contacts the substrate 102 on which the light emitting element 101 is mounted. Further, the light-emitting element 101 is fitted so as to surround itself. Reference numeral 108 denotes a light exit from the light guide 106, and this portion serves as an opening of the light guide cover 103! /. 111 is a reflection / diffusion surface provided along the longitudinal direction of the light guide 106, and light incident on the reflection / diffusion surface 111 is diffused, and a part of the light is emitted to face the reflection / diffusion surface 111. Irradiate the document through surface 107 and exit 108. Reference numeral 105 denotes a light receiving end face of the light guide 106, and the light emitted from the light emitting element 101 is received by the end face 105 and guided to the inside of the light guide 106.

FIG. 3 is a cross-sectional view of the light guide body 106 according to the present embodiment, and portions common to the above-described drawings are indicated by the same symbols.

FIG. 4 is an enlarged cross-sectional view of the vicinity of the light emitting element 101 in the line illumination device 100 according to Embodiment 1 of the present invention.

As shown in FIG. 4, in the line illumination device 100 according to the present embodiment, the size of the light emitting element 101 is smaller than the cross section of the light guide 106. The light guide body strength bar 103 extended to the light emitting element 101 has an extension portion 110 that covers the air layer 104 and contacts the substrate 102 on which the light emitting element 101 is mounted. Further, the light guide cover 103 is fitted so as to surround the side surface of the light emitting element 101 (in this embodiment, the LED package itself).

The radiated light 112 radiated from the light emitting element 101 includes a light beam that directly reaches the light receiving end surface 105 of the light guide body 106 and a light beam that has a large radiation angle and reaches the inner side surface 113 of the light guide body cover 103. It is configured. The light beam reaching the inner side surface 113 of the light guide cover 103 is reflected by the inner side surface 113 of the light guide cover 103 made of white polycarbonate, or further this light guide. After repeatedly reflecting on the inner surface 113 of the physical strength bar 103, the light reaches the light receiving end surface 105 of the light guide 106 and the light guide 106. In this way, by forming the light guide cover 103 so as to integrally cover the light emitting element 101 and the light guide 106, the light emitted from the light emitting element 101 can be efficiently incident on the light guide 106. it can.

[0026] The illuminance distribution in the longitudinal direction at the exit 108 of the line illumination device 100 according to the first embodiment was measured. As a comparative example, the extension 110 of the light guide cover 103 shown in FIG. 4 is manufactured in the corresponding comparison frame 115 of the light guide attachment frame 31 of the conventional line illumination device shown in FIG. The comparative line lighting device 116 illustrated in FIG.

FIG. 11 is a partially enlarged cross-sectional view of a comparative line illumination device in which the line illumination device according to the first embodiment is provided as a comparison frame corresponding to the light guide mounting frame shown in FIG. .

In FIG. 11, a comparison frame 115 is extended from the substrate 102 side using the same material as the light guide cover 103 of Embodiment 1, and receives light from the light emitting element 101, the air layer 104, and the light guide 106. The frame shape covers up to the vicinity of the end face 105. Here, the light guide cover 103 and the comparison frame 115 are almost in contact with each other via the boundary 117!

[0029] The illuminance distribution at the exit 108 of the comparative line illumination device 116 was measured under the same conditions as in the first embodiment, and compared with the illuminance distribution in the first embodiment as an average value. As a result, it was confirmed that the illuminance of the first embodiment was about 5% higher! /.

[0030] According to the first embodiment, there are the following advantages.

[0031] The length of the light guide 106 made of acrylic is slightly expanded / contracted due to moisture absorption or the like, and the distance between the light emitting element 101 and the light receiving end face 105 of the light guide 106 varies in the air layer 104. . As a result, the amount of radiated light that can be directly received by the light receiving end face 105 of the radiated light 112 from the light emitting element 101 changes, and the amount of light that can be directly received by the light guide 106 changes.

On the other hand, in the configuration of the line illumination device 100 according to the first embodiment, the amount of light emitted from the line illumination device 100 is small because the amount of light incident on the light guide 106 hardly changes. There was no change.

Furthermore, in the line illumination device 100 according to the first embodiment, the extension 110 that extends so that the light guide cover 103 contacts the base plate 102 covers the outer shape of the light emitting element 101. Therefore, a commercially available LED can be used as it is for the light-emitting element 101. This facilitates selection of components of the light emitting element 101, which is advantageous in terms of manufacturing cost of the line illumination device 100.

In FIG. 4, a force indicating the shape of the inner side surface 113 in a straight line may be a paraboloid shape having the light emitting point of the light emitting element 101 as a focal point. This is preferable because the light condensing effect is increased and the light use efficiency from the light emitting element 101 can be increased.

[Embodiment 2]

FIG. 5 is an enlarged cross-sectional view of the vicinity of the light emitting element 101 in the line illumination device 100 according to Embodiment 2 of the present invention. In the second embodiment, the size of the light emitting element 101 is shown as being larger than the light receiving end face 105 of the light guide 106. The light-emitting element 101 used in this embodiment is an LED (model number; NS6W083, manufactured by Nichia Corporation), and has dimensions of 6.5 X 5. Omm and a thickness of 1.35 mm. The outer size of the light emitting element 101 is larger than the cross section (light receiving end face 105) of the light guide 106.

In the second embodiment, the light beam from the light emitting element 101 has the opening shape of the extension 110 of the light guide cover 103 enlarged, and the light emitting element 101 is fitted as in FIG. As a result, the light emitted from the light emitting element 101 is efficiently incident on the light guide 106.

[0037] Instead of the air layer 104 between the light emitting element 101 and the light receiving end face 105, it is also preferable to form the region with a transparent resin layer. In this case, the transparent resin layer can efficiently enter the light guide 106 by appropriately selecting the distance and shape between the light emitting element 101 and the light receiving end face 105. The resin used for the resin layer is preferably a polycarbonate resin, an acrylic resin, or an epoxy resin having optical properties similar to those of the light guide 106.

[0038] The light guide cover 103 according to the second embodiment can easily accommodate and cover the transparent resin layer formed as described above. After passing through this transparent resin layer, the radiant light having reached the inner surface 11 3 of the light guide cover 103 is reflected / scattered without leaking to the outside, or further, the reflection on the inner surface 113 is repeated. Light can enter the light receiving end face 105.

The light incident on the light guide 106 is guided in the longitudinal direction of the light guide 106 by repeating total reflection in the light guide 106. A part of the light guide 106 is provided with a reflection / diffusion surface 111 along the longitudinal direction of the light guide 106. When light enters the reflective surface 111, the incident The part of the light is diffused, and a part of the light passes through the exit surface 107 facing the reflecting / diffusing surface 111 and irradiates the original reading line 205 (see FIG. 6).

[0040] With such a configuration, it is possible to form a line illumination device 100 that efficiently uses light emitted from the light emitting element 101.

[0041] Furthermore, since the light emitting element 101 is configured to fit into the light guide cover 103 as in the first embodiment, the light guide cover 103 includes the light emitting element 101, the light guide 106, and the like. In this structure, the change in the amount of light incident on the light guide 106 is less likely to occur.

[0042] Further, the surface treatment of the inner surface 113 of the light guide cover 103 with a metal thin film having a metallic gloss surface by electroless plating or the like, or coating with titanium oxide, Effective because radiation efficiency can be effectively used by improving light reflection efficiency

[0043] As another method of surface treatment of the inner surface 113 of the light guide cover 103, the surface that contacts the inner surface 113 of the light guide cover 103 of the mold for molding the light guide cover 103 is mirror-finished. Accordingly, the inner surface 113 of the molded light guide cover 103 may be mirror-finished.

[0044] Thereby, the reflectance of light on the inner side surface 113 is improved, and the light emitted from the light emitting element 101 can be efficiently incident on the light guide 106. Whether to limit the surface treatment of the inner side surface 113 of the light guide cover 103 to the entire surface of the inner side surface 113 or the vicinity of the light receiving end surface 105 should be determined in consideration of cost effectiveness and the like. Is good.

[0045] Furthermore, instead of surface-treating the inner side surface 113 of the light guide cover 103, a light guide cover is provided.

A covering made of a metal plate may be provided on the outside of the extension portion 110 of 103. Thereby, the light leaking through the light guide cover 103 can be returned to the light guide cover 103 side, and a part of the light can be incident on the light guide 106. Thereby, light can be used efficiently.

In the first and second embodiments described above, the case where one end face side of the light guide 106 is the light receiving end face and the light emitting element 101 is disposed on the light receiving end face side has been described. However, the line illumination device of the present invention is not limited to this. For example, a light emitting element is provided on the other end face side of the light guide 106, and the light guide cover is similarly attached to the light emitting element. You can extend and mold it!

FIG. 6 is a perspective view schematically showing a contact image sensor 200 using the line illumination device 100 described above, and FIG. 7 is a cross-sectional view taken along line II II in FIG.

[0048] As shown in FIGS. 6 and 7, the contact image sensor 200 has a box-shaped frame.

A linear illumination device 100, a rod lens array 202, and a sensor array substrate 203 described above are housed in 201. The contact image sensor 200 illuminates a document placed on a glass platen (not shown) such as a glass on the upper side thereof, receives light reflected from the document of the illumination light, and performs photoelectric conversion. .

More specifically, in the contact image sensor 200, the line illumination device 100 illuminates the document reading line 205 in a line shape. The light thus illuminated is reflected from the document, and the optical information at the reading position is received by the rod lens array 202 and imaged on the line sensor 204 arranged on the sensor array substrate 203. The line sensor 204 has a mechanism capable of reading a document by converting the imaged light into an electrical signal and outputting it.

[0050] By using such a line illumination device 100, it is possible to provide a contact image sensor in which a change in illuminance characteristics due to the use environment is suppressed to be small.

FIG. 8 is an external perspective view of a flatbed image scanner (image reading apparatus) 300 using the contact image sensor 200 equipped with the line illumination device 100 according to the embodiment of the present invention.

In the image reading apparatus 300, a contact image sensor 200 shown in FIG. Further, a drive motor 302 and a wire 303 for moving the contact image sensor 200 are provided in the housing 301. A glass plate 304 is provided on the upper surface of the housing 301 as a document support. Further, a pressure plate 305 for pressing a document placed on the glass plate 304 against the glass plate 304 is attached to the end of the housing 301 so as to be openable and closable.

In the image scanner configured as described above, an original is placed downward on the glass plate 304, the pressure plate 305 is closed and the driving motor 302 is driven by the force and the wire 303 is mechanically moved. As a result, the contact image sensor 200 moves in the reading direction (scanning direction) and the original image is displayed. Can read the image.

This close contact image sensor 200 is configured as a sensor unit in which the above-described line illumination device 100 is incorporated in a body. The reflected light from the original illuminated by the light from the line illumination device 100 is condensed on a photoelectric conversion element (line sensor) by the rod lens array in the contact image sensor 200, and an image is obtained for each scanning line. Output as information. This image information is output to a connected external device via an interface such as USB or IEEE1394. Alternatively, it is output to an external device by wireless communication such as Bluetooth.

In this manner, an image scanner that can read and output image information of a sheet-like document can be provided.

[0056] As described above, the contact image sensor or the image reading apparatus using the line illumination device according to the present embodiment can obtain stable image quality without depending on the use environment.

Claims

The scope of the claims

[1] a light emitting device;

A long light guide that receives light emitted from the light emitting element from an end surface, guides the received light in a longitudinal direction, and emits light from an emission surface;

A linear illumination device comprising:

[2] The line illumination device according to [1], wherein the light emitting element includes a plurality of light emitting diodes.

[3] The line illumination device according to [1], wherein an air layer covered with the light guide cover is provided between the light emitting element and the end face!

4. The line illumination device according to claim 1, wherein a transparent resin layer covered with the light guide cover is provided between the light emitting element and the end face.

5. The line according to claim 1, wherein an inner side surface between the light emitting element and the end face of the light guide cover has a parabolic shape with a light emitting point of the light emitting element as a focal point. Lighting device.

6. The line shape according to claim 1, wherein an inner surface between the light emitting element and the end surface of the light guide cover is subjected to a surface treatment for reflecting light. Lighting device.

7. The line illumination device according to claim 6, wherein the surface treatment is a treatment of forming a metal thin film on the inner side surface.

8. The line illumination device according to claim 6, wherein the surface treatment is a mirror finish.

9. The line illumination device according to claim 1, further comprising a light reflecting metal plate provided on an outer surface between the light emitting element and the end surface of the light guide cover.

[10] The elongate light guide has a reflection / diffusion surface for reflecting and diffusing light at a position facing the emission surface in the longitudinal direction of the light guide. The line illumination device according to claim 1.

[11] The line illumination device according to claim 1,

A photoelectric conversion element that converts optical information imaged on the sensor surface into an electrical signal; and a lens for imaging optical information of a reading position on the sensor surface of the photoelectric conversion element,

An image sensor, wherein the line illumination device, the photoelectric conversion element, and the lens are accommodated in one frame.

[12] The image sensor according to claim 11,

Driving means for relatively moving the image sensor and the document;

Output means for outputting an image signal read by the image sensor to an external device in synchronization with the relative movement by the driving means;

An image reading apparatus comprising: