JPWO2008013234A1 - Line illumination device, image sensor, and image reading device using the same - Google Patents

Abstract

The present invention provides a line illuminating device that efficiently emits radiated light from a light emitting element into a light guide, and an image sensor and an image reading device using the line illuminating device. For this purpose, a light emitting element, a long light guide that receives light emitted from the light emitting element from the end face, guides the received light in the longitudinal direction, and emits light from the emitting face, and a light guide A light guide cover that covers the light body and has an opening for allowing light emitted from the light exit surface of the light guide to pass therethrough and that fits the light emitting element beyond the end face of the light guide. Have.

Description

  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.

  2. Description of the Related 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, a contact image sensor (hereinafter referred to as CIS) is composed of an illuminating device, an equal magnification imaging optical device, a photoelectric conversion element, and the like. The CIS generally has a feature that the device can be easily miniaturized because the optical path length is shorter than that of an image sensor using a reduction optical system. For this reason, it can be easily incorporated into a device, and instead of a reduction optical system, it has been widely used in a thin flat bed type image reading apparatus. The line-shaped illumination device used for this CIS is required to illuminate the original surface with a required illuminance or higher and the reflected light from the original reaches the photoelectric conversion element with a sufficient amount of light.

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

  In FIG. 9, reference numeral 43 denotes a frame that supports the structural members, 44 denotes a lens array that forms an optical image of the document on the line sensor 45, and 45 includes a plurality of light receiving units that photoelectrically convert the optical image of the document into electrical signals. This is a line sensor arranged in a line. Reference numeral 46 denotes a sensor substrate on which the line sensor 45 is mounted. Reference numerals 41r, 41g, and 41b denote light-emitting elements 41 that are light-emitting diodes (hereinafter referred to as LEDs) for illuminating a document, and are disposed on the end surface of the light guide 42 that extends in the longitudinal direction. The line illumination device has a light guide 42 that takes in the radiated light from the LED and is designed so that the amount of illumination light is substantially uniform over the length of one line of the document reading unit. Reference numeral 47 denotes a connector for connecting a sensor signal to an external device, and reference numeral 48 denotes a transparent glass document support table for supporting the document 49.

  In general, light emitted from a light emitting element disposed on the end face of the light guide 42 is guided into an acrylic light guide 42 and is emitted from the emission surface to the outside while being complicatedly reflected. The document 49 is illuminated.

As such a line illuminating device, those having various shapes are used, and recently, a prismatic one 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 formed integrally with the LED light source unit 30. Furthermore, the light guide 20 is provided with a light guide cover (not shown) outside thereof.
JP 2005-236940 A

  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 instead of a commercially available LED. Further, depending on the shape of the light guide, it is necessary to enlarge the light guide attachment frame 31, and accordingly, it is necessary to increase the shape of the LED light source unit 30.

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

  In addition, the present invention is characterized in that the light emitting element and the light guide are covered with the same light guide cover, and a line-shaped illumination device capable of efficiently allowing the emitted light from the light emitting element to enter the light guide is provided. There is to do.

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

In order to achieve the above object, a line illumination device according to one embodiment 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 light exit surface of the light guide to pass through, and that fits the light emitting element beyond the end face of the light guide. Body cover,
It is characterized by having.

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 in consideration of insertion of a light guide on the light emitting element side becomes unnecessary.
(3) The light emitting element and the light guide can be easily positioned.

It is a perspective view which shows roughly the linear illuminating device 100 which concerns on Embodiment 1 of this invention. It is sectional drawing which follows the line II of FIG. It is sectional drawing of the light guide of the linear illuminating device which concerns on this Embodiment. It is an expanded sectional view of the vicinity of the light emitting elements in the line illumination device according to Embodiment 1 of the present invention. It is an enlarged view of the light emitting element vicinity in the line-shaped illuminating device which concerns on Embodiment 2 of this invention. 1 is a perspective view schematically showing a contact image sensor using a line illumination device according to the present embodiment. It is sectional drawing which follows the line II-II of FIG. 1 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. It is a structure sectional view of the conventional contact type image sensor. It is a figure which shows the structure of the conventional line-shaped illuminating device. It is a partially expanded sectional view of the comparative line-shaped illuminating device which provided the line-shaped illuminating device which concerns on this Embodiment 1 as a comparison frame applicable to the light guide attachment frame shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Line-shaped illuminating device 101 Light emitting element 102 Board | substrate 103 Light guide cover 104 Air layer 105 Light-receiving end surface (end surface)
106 light guide 108 light exit 110 extension

  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. Not exclusively.

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

  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 length and width of 3.5 mm. The LED is disposed on a copper substrate 102 having a thickness of 2 mm for heat dissipation.

  The light emitting element (light source) 101 can be formed of a plurality of chips by connecting a large number of LEDs having normal brightness. Moreover, it is also possible to use three types of red, blue, and green LEDs instead of the white LEDs.

  In the present embodiment, the light guide 106 is formed by molding an acrylic resin having high light transmittance into a predetermined shape. The light guide cover 103 was formed by molding a polycarbonate resin kneaded with a white pigment. The length of the light guide 106 is usually about 230 mm in applications where an A4 size document is irradiated. Moreover, the cross-sectional shape is a fan shape (refer FIG. 3) of about 30 square mm, and is a long rod 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. The light emitting element 101 is fitted so as to surround it. Reference numeral 108 denotes a light exit from the light guide 106, and this portion is an opening of the light guide cover 103. Reference numeral 111 denotes a reflection / diffusion surface provided along the longitudinal direction of the light guide 106. Light incident on the reflection / diffusion surface 111 is diffused, and part of the light is emitted to face the reflection / diffusion surface 111. The original is irradiated through the surface 107 and the 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 into the light guide 106.

  FIG. 3 is a cross-sectional view of the light guide 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 cover 103 extended to the light emitting element 101 has an extending portion 110 that covers the air layer 104 and contacts the substrate 102 on which the light emitting element 101 is mounted. Furthermore, 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 is composed of 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. Yes. The light beam that has reached the inner surface 113 of the light guide cover 103 is reflected by the inner surface 113 of the light guide cover 103 made of white polycarbonate, or further repeatedly reflected by the inner surface 113 of the light guide cover 103. The light receiving end face 105 of the light guide 106 and the light guide 106 are reached. Thus, by forming the light guide cover 103 so as to integrally cover the light emitting element 101 and the light guide 106, the emitted light from the light emitting element 101 can be efficiently incident on the light guide 106. .

  The illuminance distribution in the longitudinal direction at the exit 108 of the line illumination device 100 according to Embodiment 1 was measured. As a comparative example, the extension 110 in 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. 11 is a comparative line illumination device 116 exemplified in FIG.

  FIG. 11 is a partially enlarged cross-sectional view of a comparative line lighting device in which the line lighting 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, the comparison frame 115 is extended from the substrate 102 side using the same material as the light guide cover 103 of the first embodiment, and is near the light receiving end face 105 of the light emitting element 101, the air layer 104, and the light guide 106. The frame shape covers up to. Here, the light guide cover 103 and the comparison frame 115 are substantially in contact with each other via the boundary 117.

  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 and the average value. As a result, it was confirmed that the illuminance of the first embodiment was about 5% higher.

  The first embodiment also has the following advantages.

  The acrylic light guide 106 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 surface 105 of the radiated light 112 from the light emitting element 101 changes, and the amount of light that the light guide 106 can directly receive changes.

  On the other hand, in the configuration of the line illumination device 100 according to the first embodiment, since the amount of light incident on the light guide 106 hardly changes, the amount of light emitted from the line illumination device 100 changes. I couldn't.

  Furthermore, in the line illumination device 100 according to the first embodiment, the light emitting element 101 has a structure in which the extension 110 extended so that the light guide cover 103 contacts the substrate 102 covers the outer shape of the light emitting element 101. A commercially available LED can be used as it is. This facilitates component selection of the light emitting element 101, which is advantageous in terms of manufacturing cost of the line illumination device 100.

  In FIG. 4, the shape of the inner side surface 113 is shown as a straight line, but the inner side surface 113 may have a parabolic shape with 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), the dimensions are 6.5 × 5.0 mm in length and width, and the thickness is 1.35 mm. The outer size of the light emitting element 101 is larger than the cross section of the light guide 106 (light receiving end face 105).

  In the second embodiment, the light beam from the light emitting element 101 is fitted to the light emitting element 101 in the same manner as in FIG. Thereby, the emitted light from the light emitting element 101 is efficiently incident on the light guide 106.

  Further, instead of the air layer 104 between the light emitting element 101 and the light receiving end surface 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.

  The light guide cover 103 according to the second embodiment can easily accommodate and cover the transparent resin layer thus formed. The light emitted from the light source that has reached the inner side surface 113 of the light guide cover 103 is reflected and scattered without leaking to the outside through this transparent resin layer, or is further reflected on the inner side surface 113 and then received. Light can enter the 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 reflection / diffusion surface 111, the incident light is diffused, and a part of the light passes through the emission surface 107 facing the reflection / diffusion surface 111 to irradiate the original reading line 205 (see FIG. 6).

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

  Further, since the light emitting element 101 is fitted to the light guide cover 103 as in the first embodiment, the light guide cover 103 has the respective centers of the light emitting element 101 and the light guide 106. There is no positional shift, and the light amount incident on the light guide 106 does not easily change.

  In addition, surface treatment of the inner side 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 can improve the reflection efficiency of light from the light emitting element 101. It is effective because it can improve and effectively use the emitted light.

  As another method of surface treatment of the inner surface 113 of the light guide cover 103, by mirror-finishing the surface that contacts the inner surface 113 of the light guide cover 103 of the mold for molding the light guide cover 103, The inner surface 113 of the molded light guide cover 103 may be mirror finished.

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

  Furthermore, instead of subjecting the inner side surface 113 of the light guide cover 103 to the surface treatment, a metal plate covering may be provided outside the extension 110 of the light guide cover 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 enter 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 a 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 may be provided on the other end face side of the light guide 106, and the light guide cover may be extended and molded similarly to the light emitting element.

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

  As shown in FIGS. 6 and 7, the contact image sensor 200 is configured by housing the above-described line illumination device 100, the rod lens array 202, and the sensor array substrate 203 in a box-shaped frame 201. is doing. The contact image sensor 200 illuminates a document placed on a document table (not shown) such as glass on the top, 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 formed on the line sensor 204 arranged on the sensor array substrate 203. The line sensor 204 is configured to be able to read a document by converting the imaged light into an electrical signal and outputting it.

  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 a small level.

  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 this 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 casing 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 on the glass plate 304 downward, the pressure plate 305 is closed, and then the drive motor 302 is driven to mechanically move the wire 303. As a result, the contact image sensor 200 can move in the reading direction (scanning direction) to read a document image.

  The contact image sensor 200 is configured as a sensor unit in which the above-described line illumination device 100 is integrated. The reflected light from the original illuminated by the light from the line illumination device 100 is condensed on the photoelectric conversion element (line sensor) by the rod lens array in the contact image sensor 200, and image information is obtained for each scanning line. Is output as 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.

  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.

In order to achieve the above object, a line illumination device according to one embodiment of the present invention has the following configuration. That is,
A light emitting element;
Received from the end face of the light emitted from the light emitting element, an elongated lightguide for emitting light from the emission surface while guided to the long side direction,
A linear illumination device having a light guide cover having an opening for passing the Shako output from the light guide with covering the light guide,
The light guide cover has a structure that extends beyond the end face of the light guide and covers and fits the side surface of the light emitting element, whereby the positional relationship between the light emitting element and the light guide. It has the function which prescribes | regulates .

Claims (12)

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 light exit surface of the light guide to pass through, and that fits the light emitting element beyond the end face of the light guide. Body cover,
A linear illumination device comprising:   The line illumination device according to claim 1, wherein the light emitting element includes a plurality of light emitting diodes.   The line illumination device according to claim 1, wherein an air layer covered with the light guide cover is provided between the light emitting element and the end face.   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.   The linear illumination device according to claim 1, wherein an inner side surface between the light emitting element and the end surface of the light guide cover has a parabolic shape with a light emitting point of the light emitting element as a focal point. .   The line-shaped illumination device according to claim 1, wherein an inner side surface between the light emitting element and the end surface of the light guide cover is subjected to a surface treatment for reflecting light.   The line-shaped illumination device according to claim 6, wherein the surface treatment is a treatment of forming a metal thin film on the inner side surface.   The line-shaped lighting device according to claim 6, wherein the surface treatment is a mirror finish.   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.   The elongate light guide has a reflection / diffusion surface for reflecting and diffusing light at a position facing the emission surface over the longitudinal direction of the light guide. The line-shaped illuminating device according to 1. A line illumination device according to claim 1;
A photoelectric conversion element that converts optical information imaged on the sensor surface into an electrical signal;
A lens for imaging the optical information of the 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. An 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 relative movement by the driving means;
An image reading apparatus comprising:

Images