JP2008271009A - Linear light source device and image scanner equipped with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear light source device and an image scanner equipped with the same which are capable of lighting so as to make no shadow even if there are folding lines and crimples on a manuscript and capable of realizing a cost reduction and an eco-friendliness. <P>SOLUTION: The linear light source device is formed integrally from resin and includes an approximately U-shaped light guiding body 10 in which one ends of approximately columnar linear portions 11, 12 are connected that extend parallel to each other at given intervals therebetween, and an LED luminescent device 20 arranged opposite to at least any one of the other ends of the linear portions 11, 12. In peripheral surfaces of the linear portions 11, 12, belt-like reflecting regions 14, 15 formed with a plurality of concave portions 16 or convex portions 17 are provided at one side of a reference plane containing axes of these linear portions 11, 12 and besides in a cross-section of the linear portions 11, 12, as straight lines which connect a center of each of the linear portions 11, 12 and a center of a width direction in each of the reflecting regions 14, 15 get nearer to one side of the reference plane, the distance between the straight lines gets larger. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a linear light source device used for illuminating a document and an image reading apparatus including such a linear light source device.

  For example, Patent Document 1 describes an image reading apparatus including a conventional linear light source device. FIG. 7 schematically shows an example of such an image reading apparatus in a sectional view. In the image reading apparatus Y shown in FIG. 7, a document C is placed on a transparent glass plate 930, and this document C is illuminated by a single linear light source device X in a linear reading region D. The light reflected by the original C in the reading area D is reflected by the reflecting mirrors 941, 942, and 943 and then enters the imaging lens 950. Further, the light emitted from the imaging lens 950 is imaged on a CCD line sensor 960 in which a plurality of pixel portions are formed in a line at a predetermined pixel pitch. In this way, the image reading apparatus Y can read the document C placed in the reading area D. For example, a cold cathode tube or a halogen lamp is used as the linear light source device X.

  However, in such an image reading apparatus Y, as shown in FIG. 8, if the document has a fold or a wrinkle, the light from the linear light source apparatus X hits as shown by the hatched portion in FIG. In other words, a shaded area that cannot be read may occur. Furthermore, although cold cathode fluorescent lamps and halogen lamps emit light from the entire circumference, since the direction to be illuminated is one direction, it is necessary to provide a reflecting member 970 or the like in order to reduce wasted light. In addition, cold cathode fluorescent lamps and halogen lamps need to obtain a high voltage to obtain a discharge voltage, which raises the cost of the power supply circuit and the problem that mercury vapor is contained inside and is not favorable for the environment. was there.

Japanese Patent Laid-Open No. 11-146157

  The present invention has been conceived under the circumstances described above, and can illuminate so as not to be shaded even if there is a crease or wrinkle on the document. Further, the cost can be reduced and the environment can be reduced. It is an object of the present invention to provide a preferable linear light source device and an image reading device including such a linear light source device.

  The first linear light source device of the present invention is formed of a resin and is substantially U-shaped by connecting substantially cylindrical first and second linear portions extending in parallel with each other at a predetermined interval on one end side thereof. A linear light source device comprising: a light guide formed in a letter shape; and an LED light emitting device disposed opposite to at least one other end of the first and second linear portions. The outer peripheral surfaces of the first and second straight portions are provided with a belt-like reflection region in which a plurality of concave portions or convex portions are formed on one side of a reference plane including the axes of these straight portions. In the cross section of the first and second straight portions, the distance between the straight lines connecting the centers of the straight portions and the width direction centers of the reflective regions increases toward one side of the reference plane. Is characterized by spreading.

  According to such a configuration, the light emitted from the LED light emitting device and incident on the linear portion of the light guide travels in the longitudinal direction of the light guide while being totally reflected inside the light guide. Such light is irregularly reflected by the concave portion or the convex portion of each reflection region, and a part of the light is emitted from the surface of the linear portion opposite to each reflection region. Furthermore, since the light emitted from the opposite surface of each reflection region in the first and second straight portions is configured to approach each other, one object is targeted by the first and second straight portions. Illumination can be performed from two directions. For this reason, when this linear light source device is used, since the reading target is illuminated from two directions, it becomes difficult to form a shaded portion. Furthermore, since this linear light source device is configured to emit light mainly from the opposite surface of each reflection region, there is no need to provide a reflection member outside. Furthermore, since the light guide is integrally formed of resin, it is difficult to break, and since the light source is an LED, power consumption can be suppressed.

  In a preferred embodiment, an LED light emitting device is disposed opposite to the other end portions of both the first and second linear portions, and each LED light emitting device is mounted on a common substrate. According to such a configuration, since light is incident on the first and second straight portions from the separate LED light emitting devices, the light emitted from each of the first and second straight portions is The brightness will be the same, and one will not be extremely dark or bright.

  In a preferred embodiment, the substrate is made of aluminum nitride, and a heat sink made of aluminum or aluminum alloy is laminated on the substrate. According to such a configuration, the heat generated when the LED light emitting devices are driven can be suitably released.

  An image reading apparatus provided by a second aspect of the present invention includes a light source device for illuminating a linearly extending reading area, and a sensor for acquiring an image of the reading area. The linear light source device provided as the light source device according to the first aspect of the present invention is configured such that light emitted from both the first and second linear portions illuminates the reading area. It is characterized by being used.

  According to such a configuration, the image reading apparatus can also read portions such as folds and wrinkles of the document. Furthermore, when the linear light source device according to the first aspect of the present invention is used, there is no need to provide a reflecting member, so that the image reading device can be made more compact and the manufacturing cost can be reduced.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  An embodiment of a linear light source device according to the first aspect of the present invention is shown in a front view in FIG. 1 and in a rear view in FIG. 3 shows a cross-sectional view taken along line III-III in FIG. 1, and FIG. 4 shows a cross-sectional view taken along line IV-IV in FIG. The linear light source device A includes a light guide 10 and an LED light emitting device 20.

  The light guide 10 is integrally formed in a substantially U shape by a transparent resin such as PMMA or polycarbonate, and its peripheral surface has a smooth mirror surface. The light guide 10 includes a straight portion 11, a straight portion 12, a curved portion 13 that connects the straight portion 11 and the straight portion 12, and reflection regions 14 and 15. The straight portions 11 and 12 are each formed in a substantially cylindrical shape having a substantially circular cross section, and extend parallel to each other with a predetermined interval. One end of each of the straight portions 11 and 12 is connected to the bending portion 13. Square shaped socket portions 11 a and 12 a are integrally formed at the other ends of the straight portions 11 and 12, and the socket portions 11 a and 12 a are connected to the LED light emitting device 20. The socket portions 11 a and 12 a are formed with a recess 19 whose bottom surface is orthogonal to the axis of the straight portions 11 and 12. The bending portion 13 includes reflection portions 13a and 13b that intersect the central axes of the straight portions 11 and 12 at an angle of 45 ° in the plan view shown in FIGS. The diameters of the cross sections of the straight portions 11 and 12 and the curved portion 13 are, for example, about 4 mm.

  The reflection regions 14 and 15 are provided on the outer peripheral surfaces of the straight portions 11 and 12, have a predetermined width, and are formed in a strip shape extending along the longitudinal direction of the straight portions 11 and 12. As shown in FIG. 3, the reflection regions 14 and 15 are formed below the reference plane P including the central axes of the straight portions 11 and 12. In FIG. 3, the symbol L <b> 1 indicates a straight line passing through the center in the width direction of the reflective region 14 and the center of the cross section of the straight portion 11. A straight line passing through the center is shown. The straight line L1 and the straight line L2 are inclined such that the distance therebetween increases as it goes downward in FIG. 3, and the distance between the lines L1 and L2 approaches as it goes upward in FIG. The reflective regions 14 and 15 have the same structure, although they are inclined in different directions. As shown in FIG. 2, the reflection regions 14 and 15 include the recesses 16 and the projections 17 alternately arranged along the longitudinal direction of the reflection regions 14 and 15, and the reflection regions 14 and 15 sandwiching the recesses 16 and the projections 17. And a pair of flat portions 18 extending over the entire length in the longitudinal direction. As shown in FIG. 4, the bottom of the recess 16 has a cylindrical inner surface, and the protrusion 17 is formed in a flat surface connected to the recess 16 by a smooth cylindrical outer surface. The pair of flat portions 18 are located in the same plane and are formed to be parallel to the central axes of the straight portions 11 and 12.

  The width of the reflective regions 14 and 15 is 1.6 mm, for example, the width of each flat portion 18 is 0.35 mm, for example, and the height of the flat surface of the convex portion 17 with respect to the flat portion 18 is 0.19 mm, for example. The depth of the recess 16 with respect to the surface is set to 0.18 mm, for example, and the formation pitch of each recess 16 is set to 1.5 mm, for example. However, these dimensions can be variously set according to the diameters of the straight portions 11 and 12. In this embodiment, the concave portion 16 and the convex portion 17 are formed so as to extend in a uniform cross section in the width direction of the reflective regions 14 and 15, but on the flat surface formed in the reflective regions 14 and 15. A concave spherical recess or a convex spherical protrusion may be provided.

  The LED light emitting device 20 includes a substrate 21, a heat radiating plate 22, and an LED 23. The substrate 21 has, for example, a long rectangular shape, and LEDs 23 are mounted at predetermined positions near both ends in the longitudinal direction, and the remaining area is used as a heat dissipation and wiring pattern placement area. As the material of the substrate 21, for example, aluminum nitride is used. The heat radiating plate 22 is formed in an L shape in a plan view in FIG. 1, and is bonded to the back side of the substrate 21 in a laminated form. The heat sink 22 is made of aluminum or an aluminum alloy. The LED 23 is surrounded by the recesses 19 of the sockets 11 a and 12 a and is arranged so that the light emitting surface thereof faces the bottom surface of the recess 19. For example, a package-type white LED is preferably used as the LED 23, but red, green, and blue LED bare chips may be used.

  The light guide 10 and the LED light emitting device 20 are connected by bonding the sockets 11 a and 12 a and the substrate 21.

  Next, the operation of the linear light source device A will be described.

  In such a linear light source device A, when the LED light emitting device 20 is turned on, the light emitted from the LED 23 enters the linear portions 11 and 12 from the bottom surface of the recess 19. As schematically shown in FIG. 4, the light incident on the straight portions 11 and 12 travels in the longitudinal direction while being totally reflected by the smooth surfaces of the straight portions 11 and 12. A part of such light is reflected by the recess 16 and the traveling direction is changed in a direction crossing the straight portions 11 and 12. The light whose traveling direction has been changed in this way generally travels toward the region opposite to the reflecting regions 14 and 15 in the straight portions 11 and 12, as schematically shown in FIG. Among these lights, the light incident on the outer peripheral surfaces of the straight portions 11 and 12 at an angle smaller than the total reflection critical angle is emitted to the outside of the straight portions 11 and 12. Since the straight portions 11 and 12 are formed in a substantially cylindrical shape and the outer peripheral surface thereof is a convex surface, it is possible to suppress the emitted light from spreading in the circumferential direction of the straight portions 11 and 12. For this reason, as shown in FIG. 3, the light radiate | emitted from the linear parts 11 and 12 is concentrated on the intersection of the straight lines L1 and L2.

  Since the reflection regions 14 and 15 of the linear light source device A extend along the longitudinal direction of the straight portions 11 and 12, the region where the light emitted from the straight portions 11 and 12 intersects and is illuminated brightly is also a straight line. It has a linear shape extending along the longitudinal direction of the portions 11 and 12. Therefore, the linear light source device A can irradiate the linear irradiation target from two directions only by turning on the two LEDs 23. For this reason, when the original is illuminated using the linear light source device A, it is difficult for the original to be shaded even if the original has folds or wrinkles.

  Since the linear light source device A can obtain linear illumination light by simply lighting two LEDs 23, it operates with less power than conventional linear light source devices such as cold cathode tubes and halogen lamps. be able to. Further, since a high voltage is not required for driving, it is not necessary to provide a booster device or the like in the power supply circuit, and cost can be reduced.

  Since the light guide 10 of the linear light source device A is integrally formed of a transparent resin, it is difficult to break. As described above, the linear light source device A has no environmental problems since it does not contain gas and does not use mercury vapor, unlike a cathode ray tube or a halogen lamp.

  Further, the substrate 21 is formed of aluminum nitride, and the heat sink 22 is formed in an L-shaped cross section to increase the surface area, so that heat generated when the LED 23 is driven can be quickly released. it can. Since both of the two LEDs 23 are mounted on one substrate 21, the heat dissipation effect by the heat sink 22 can be preferably obtained. From the above, the two LEDs 23 are less likely to reach a high temperature, and the two LEDs 23 can be continuously lit at a high output for a long time.

  Furthermore, since the linear light source device A is configured to emit light from the region opposite to the reflective regions 14 and 15, it is not necessary to provide a reflective member outside.

  Moreover, since LED23 is arrange | positioned inside the sockets 11a and 12a of both the linear parts 11 and 12, the light radiate | emitted from each of the linear parts 11 and 12 becomes comparable brightness, and one becomes extremely dark. Or brighten up.

  An embodiment of an image reading apparatus according to the second aspect of the present invention is schematically shown in a sectional view in FIG. An image reading device B shown in FIG. 5 includes the above-described linear light source device A, a transparent mounting plate 30, reflecting mirrors 41, 42, and 43, an imaging lens 50, a line sensor 60, and a housing 70. Yes. The housing 70 houses the linear light source device A, the reflecting mirrors 41, 42, 43, the imaging lens 50, and the line sensor 60. The housing 70 is configured to be movable along the left-right direction in FIG. FIG. 5 shows the straight lines L1 and L2 shown in FIG. 3, the original C placed on the placing plate 30, and the optical path from the original C to the line sensor 60.

  The line sensor 60 is, for example, a CCD, and includes a plurality of pixel portions arranged in a line at a predetermined pixel pitch. The reading region D extends linearly along a direction perpendicular to the cross section of FIG. The upper document C can be read. As shown in FIG. 5, the reflected light from the document C in the reading region D irradiated by the linear light source device A is sequentially folded by the reflecting mirrors 41, 42, 43, enters the imaging lens 50, and the line sensor 60. Incident to. Further, the image reading apparatus B can read the entire document C by moving the housing 70 in the horizontal direction in FIG. In the image reading device B, the linear light source device A is arranged so that the intersection of the straight lines L1 and L2 overlaps the reading region D in the cross section of FIG. For this reason, the light radiate | emitted from the linear parts 11 and 12 of the linear light source device A advances along the straight lines L1 and L2, respectively, and can irradiate the reading area D from two directions.

  Therefore, in the image reading apparatus B, the document C is irradiated from two directions, so that even if the document C has folds or wrinkles as shown in FIG. For this reason, the image reading apparatus B can read the original C without any shadow even if the original C has a crease or a wrinkle. Furthermore, since the linear light source device A does not need to be provided with a reflecting member, the image reading device B can be reduced in size and simplified, and the manufacturing cost can be reduced.

  The linear light source device and the image reading apparatus using the same according to the present invention are not limited to the above-described embodiments. The specific configuration of each part of the linear light source device according to the first aspect of the present invention and the image reading device according to the second aspect of the present invention can be varied in design in various ways. For example, in the above-described embodiment, the LEDs 23 are provided at the end portions of the straight portions 11 and 12, but it is also possible to implement the LED 23 only on one side.

It is a top view which shows embodiment of the linear light source device which concerns on the 1st side surface of this invention. It is a rear view of the linear light source device of FIG. It is sectional drawing which follows the III-III line of FIG. It is sectional drawing which follows the IV-IV line of FIG. It is sectional drawing which shows typically the image reading apparatus which concerns on the 2nd side surface of this invention. FIG. 6 is an enlarged view of a main part of FIG. 5 for explaining a case where the document has a fold. It is sectional drawing which shows the conventional image reading apparatus typically. FIG. 8 is an enlarged view of a main part of FIG. 7 for explaining a case where there is a fold in the document.

Explanation of symbols

A linear light source device B image reading device C document D reading region L1, L2 straight line P reference plane 10 light guide 11, 12 straight portion 13 bending portion 13a, 13b reflecting portion 14, 15 reflecting region 16 recessed portion 17 protruding portion 18 flat Part 19 Recess 20 LED light emitting device 21 Substrate 22 Heat sink 23 LED
30 Mounting plates 41, 42, 43 Reflecting mirror 50 Imaging lens 60 Line sensor

Claims (4)

A light guide that is integrally formed of resin and that is connected to each other at substantially one end thereof in a substantially cylindrical shape extending in parallel with each other at a predetermined interval, and having a substantially U-shape; An LED light-emitting device disposed opposite to the other end of at least one of the first and second linear portions, and a linear light source device comprising:
The outer peripheral surfaces of the first and second straight portions are provided with a band-shaped reflection region in which a plurality of concave portions or convex portions are formed on one side of a reference plane including the axis of these straight portions, And,
In the cross section of the first and second straight portions, the distance between the straight lines connecting the centers of the straight portions and the width direction centers of the reflective regions increases toward one side of the reference plane. A linear light source device characterized by comprising:   The LED light-emitting device is arrange | positioned facing the other end part of both the said 1st and 2nd linear parts, and each LED light-emitting device is mounted in the common board | substrate. Light source device.   The linear light source device according to claim 2, wherein the substrate is made of aluminum nitride, and a heat sink made of aluminum or aluminum alloy is laminated on the substrate. A light source device for illuminating a linearly extending reading area;
An image reading apparatus comprising: a sensor for acquiring an image of the reading area;
As the light source device, the linear light source device according to any one of claims 1 to 3 is used such that light emitted from both the first and second linear portions illuminates the reading area. An image reading apparatus characterized by comprising:

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