JP2015104056A - Lighting device and image reader including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device which maintains a good physical relationship between a light source and a light guide body, inhibits the deterioration of the light utilization efficiency, and achieves downsizing.SOLUTION: A lighting device 1000 includes: a light source 101; and a light guide body 110 which guides light from the light source 101 to a radiated surface. The light source 101 and the light guide body 110 are held by a holding member 103. The light guide body 110 includes: an incidence surface 111 into which the light from the light source enters; an emission surface 112 from which the light from the incidence surface 111 is emitted to the radiated surface; and a light guide surface 114 which guides the light from the incidence surface 111 to the emission surface 112. The light guide surface 114 includes a facing region 105 which faces the holding member 103 through air.

Description

  The present invention relates to an illuminating device and is suitable for an image reading device such as an image scanner, a copying machine, and a facsimile.

  2. Description of the Related Art Conventionally, an illuminating device using a point light source such as an LED (Light Emitting Diode) has been adopted in an image reading device that illuminates an illuminated surface (original surface) and reads it in a line sequential manner. Moreover, the structure which can guide | emit the light from a light source to an irradiated surface efficiently using the light guide which consists of a transparent member is known. In an illuminating device provided with such a light guide, not only miniaturization of the entire device but also a precise relationship between the light source and the light incident surface of the light guide and an increase in light utilization efficiency are required.

  In Patent Document 1, a light guide is installed on a substrate on which an LED is mounted, so that the positional relationship between the LED and the light guide is maintained, and the surface of the light guide that is in contact with the substrate is a reflective surface. Thus, a lighting device is disclosed in which light is prevented from going out of the light guide and reducing the light use efficiency. Furthermore, Patent Document 2 adopts a configuration in which a convex portion is extended to a portion of the incident surface of the light guide that does not face the LED, and the light guide is fixed on the substrate via the convex portion. Thus, an illumination device that reduces the cost of parts of the light guide is disclosed.

JP 2006-352310 A JP 2007-163567 A

  However, in the configuration described in Patent Document 1, the substrate and the light guide are fixed by a fixing member such as an adhesive or a double-sided tape, and the portion of the light guide facing the substrate is in close contact with the fixing member. Yes. Therefore, a part of the light from the incident surface of the light guide is incident on the fixed member, light absorption, scattering, diffuse reflection, etc. occur in the fixed member, and the light guided to the irradiated surface is reduced to use the light. Efficiency will decrease.

  Further, in the configuration described in Patent Document 2, an LED is mounted on one end of the substrate, and a circuit is mounted on a region around the other end. At this time, since the light guide extends toward the outside of the end portion on which the LED is mounted, the opposite side (above the area where the circuit is mounted on the substrate) becomes a dead space, and illumination There remains room for miniaturization of the equipment.

  Accordingly, an object of the present invention is to provide an illumination device capable of suppressing a reduction in light use efficiency and downsizing while maintaining a good positional relationship between a light source and a light guide.

  In order to achieve the above object, an illumination device according to one aspect of the present invention includes a light source and a light guide that guides light from the light source to an irradiated surface, and the light source and the light guide include: The light guide is held by a holding member, and the light guide body includes an incident surface on which light from the light source is incident, an emission surface from which light from the incident surface is emitted toward the irradiated surface, and the incident surface. A light guide surface that guides the light to the exit surface, and the light guide surface includes a facing region that faces the holding member via air.

  Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  ADVANTAGE OF THE INVENTION According to this invention, the illumination device which can suppress the fall of light utilization efficiency and size reduction can be provided, maintaining the positional relationship of a light source and a light guide favorable.

The principal part schematic of the illuminating device which concerns on Example 1 of this invention. 1 is a schematic view of a main part of an image reading apparatus including an illumination device according to an embodiment of the present invention. The principal part schematic of the illuminating device which concerns on a comparative example. The figure for demonstrating the effect of this invention. The principal part schematic of the illuminating device which concerns on Example 2 of this invention. The figure for demonstrating the shaping | molding method of the light guide which concerns on embodiment of this invention. The principal part schematic of the illuminating device which concerns on Example 3 of this invention. The principal part schematic of the light guide which concerns on the modification of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted.

[Example 1]
1A and 1B are schematic views of a main part of a lighting apparatus 1000 according to the first embodiment. FIG. 1A is a ZX sectional view and FIG. 1B is a YZ sectional view. The lighting apparatus 1000 according to the present embodiment includes a light source 101 mounted on a holding member (substrate) 103 and a light guide 110 held by the holding member 103. The light source 101 has a plurality of light emitting units (LEDs) arranged in the X direction (first direction). The light guide 110 includes an incident surface 111 on which light from the light source 101 is incident, an output surface 112 from which light from the incident surface 111 is emitted toward the irradiated surface (document surface), and light from the incident surface 111. And light guide surfaces 113 and 114 guided to the emission surface 112. The light guide 110 according to the present embodiment is fixed on the holding member 103 by a fixing member (white double-sided tape) 102, and an acrylic resin is adopted as the material of the light guide 110.

  FIG. 2 is a schematic diagram of a main part of an image reading apparatus 2000 including the illumination apparatus 1000 according to the present embodiment. An image reading apparatus 2000 according to this embodiment includes a carriage 200 that holds an illumination device 1000, folding mirrors 207a to 207d, an image forming unit 208, and a light receiving unit (line sensor) 209, and a platen glass that holds a document 203. 202. The light emitted from the illumination device 1000 is guided to the reading area of the document 203 through the reading window 206. Then, the light reflected or scattered in the reading region is condensed on the light receiving surface of the light receiving unit 209 through each of the reading window 206, the folding mirrors 207a to 207d, and the image forming unit 208.

  The image reading apparatus 2000 scans the original 203 and reads image information by moving the carriage 200 in the direction of arrow A (sub-scanning direction) in the drawing with respect to the original 203. Instead of moving the carriage 200, the relative position between the carriage 200 and the document 203 may be changed by moving the document 203 with respect to the carriage 200. The read image information is transmitted to an external device such as an image processing unit (not shown) or a personal computer through an interface.

  Next, the configuration of the lighting apparatus according to the present embodiment will be described in detail using a comparative example. FIG. 3 is a schematic diagram (YZ cross-sectional view) of a main part of a lighting device according to a comparative example. The light source 301 has a plurality of light emitting units (LEDs), and each LED generally performs Lambertian illumination. That is, each LED emits light in a range of ± 90 degrees with respect to the normal direction of the emission surface 304, and the intensity of the light emitted in the normal direction is maximized. As shown in FIG. 3, the configuration in which the emission surface 304 is perpendicular to the holding member (substrate) 303 is called a side view type, and is used in various fields such as a backlight of a liquid crystal display. .

  In order to configure an illumination device having high light utilization efficiency using such a light source 301 and a light guide 310, each of the light sources 301 and the light guide 310 is held so as not to shift. Is required. Therefore, in order to accurately maintain the positional relationship between the light source 301 and the light guide 310, the light guide 310 is held by a holding member (substrate) 303 on which the light source 301 is mounted, and the light exit surface 304 of the light source 301 and the light guide are guided. A method of arranging the incident surface 311 of the body 310 close to each other is conceivable.

  At this time, as shown in FIG. 3, the light guide 310 is fixed on the holding member 303 by a fixing member (double-sided tape, adhesive, etc.) 302. Therefore, the interface between the light guide 310 and the fixing member 302 is not an air contact surface, and the total reflection condition at the interface becomes severe (the incident angle required for total reflection is large). Therefore, a part of the light that has entered the incident surface 311 of the light guide 310 and reached the interface between the light guide 310 and the fixing member 302 is absorbed or scattered by the fixing member 302 without being totally reflected. The light guided to the illuminated surface will decrease.

  On the other hand, in this embodiment, as shown in FIG. 1, the light guide surface 114 of the light guide 110 is configured to include a facing region 105 that faces the holding member 103 via air. . Specifically, by providing protrusions 115 and 116 on the light guide surface 114 and fixing the light guide 110 to the holding member 103 via the protrusions 115 and 116, the fixing member 102 and the light guide surface 114. Is configured so as not to adhere. Thereby, since the substantially whole area of the light guide surface 114 of the light guide 110 becomes an air contact surface, light can be efficiently guided to the emission surface 112 by total reflection on the light guide surface 114. Accordingly, the dead space above the holding member 103 can be effectively used to reduce the size of the lighting device, and the light amount reaching the irradiated surface due to absorption and scattering in the fixing member 102 can be suppressed.

  In this embodiment, the protrusions 115 and 116 are formed in a linear shape extending in the arrangement direction (X direction) of the plurality of light emitting units included in the light source 101, and each is an end on the incident surface 111 side in the facing region 105. And the end on the exit surface 112 side. With this configuration, the size of the protrusions 115 and 116 can be reduced, and the stability of the light guide 110 can be increased.

  Here, the effect of disposing the light guide 110 so that the light guide surface 114 includes the facing region 105 will be described. FIGS. 4A and 4B are diagrams showing configurations of lighting devices in which the length of the light guide 410 (distance from the incident surface 411 to the output surface 412) is different from each other. At this time, in FIGS. 4 (a) and 4 (b), since the overall size of the illumination device is equal to each other, the distance from the end of the holding member 403 to the exit surface 412 and the distance from the exit surface 412 to the illuminated surface 420 are the same. The distance and the arrangement pitch of the light emitting units in the light source 401 are equal to each other.

  When the distance from the emission surface 412 to the illuminated surface 420 is the same, the configuration in which the length of the light guide 410 is longer as shown in FIG. 4B than the configuration in FIG. 4A is the illuminated surface. On 420, the area | region where the light from each light emission part overlaps becomes large. Therefore, according to the configuration of FIG. 4B, even if the number of light emitting units in the light source 401 is reduced, an increase in the size of the lighting device is suppressed, and a desired light amount in the arrangement direction (X direction) of each light emitting unit. Distribution can be obtained.

In this embodiment, as shown in FIG. 1, the length of the holding member 103 is w in the direction perpendicular to the emission surface 104 of the light source 101 (Z direction), and faces the light guide surface 114 of the holding member 103. When the length of the region is d, a configuration that satisfies the following conditional expression (1) is adopted.
d> w / 2 (1)

By adopting a configuration that satisfies the conditional expression (1), the length of the region of the holding member 103 that faces the light guide surface 114 can be sufficiently secured. Therefore, comparing the configuration satisfying conditional expression (1) with the configuration not satisfying, when the lengths of the holding member 103 and the light guide 110 are equal to each other, the configuration satisfying conditional expression (1) is smaller in size. Thus, the number of light emitting portions in the light source 101 can be reduced. Furthermore, it is more preferable to configure so as to satisfy the following conditional expression (2).
d> w / 4 (2)

  As mentioned above, according to the illuminating device which concerns on a present Example, suppression of the fall of light utilization efficiency and size reduction can be implement | achieved, keeping the positional relationship of a light source and a light guide favorable.

[Example 2]
FIGS. 5A and 5B are schematic views of a main part of the illumination device 5000 according to the second embodiment. FIG. 5A is a ZX sectional view and FIG. 5B is a YZ sectional view. The main difference between the present embodiment and the first embodiment is that the light guide surface 514 of the light guide 510 is arranged to have an angle with respect to the holding member (substrate) 503.

  Specifically, the light guide 510 includes an intersection line (edge portion) 507 formed by the incident surface 511 of the light guide 510 and the light guide surface 514, and a protrusion 515 provided on the light guide surface 514. Via the holding member 503. Accordingly, the light guide surface 514 can be inclined by the angle θ with the edge portion 507 as an axis, and the light guide surface 514 includes a facing region 505 that faces the holding member 503 via air. it can. That is, since the fixing member 502 and the light guide surface 514 can be configured not to be in close contact with each other, it is possible to suppress a decrease in the amount of light reaching the irradiated surface due to absorption or scattering in the fixing member 502.

  Here, the protrusions 515 are provided only at the end of the facing region 505 on the emission surface 512 side, and in this embodiment, the protrusions can be reduced as compared to the first embodiment. In addition, the shape of the protrusion 515 is a linear shape extending in the arrangement direction (X direction) of the plurality of light emitting units included in the light source 501, as in the first embodiment. In order to suppress light absorption and scattering in the fixing member 502, it is preferable to set the angle θ formed by the holding member 503 and the light guide surface 514 to 5 ° or more.

  As shown in FIG. 5, the light guide 510 according to the present embodiment is configured such that the angle α formed by the incident surface 511 and the light guide surface 514 is 90 ° or more (obtuse angle). The reason for this will be described in detail with reference to FIG.

  FIG. 6 is a diagram showing a state in which the light guide 600 is injection-molded using the molds (mirror surface pieces 611 and 612). When a member whose length in the X direction is longer than the length in the Z direction, such as the light guide 600 used in the illumination device provided in the image reading apparatus, is injection-molded as shown in FIG. In general, the mold is designed so that the body 600 is released in the Y direction. At this time, if the incident surface 601 and the light guide surface 602 of the light guide 600 are at right angles, the incident surface 601 is caught by the mirror piece 612 when the injection-molded light guide 600 is released, and the light guide The body 600 may be deformed.

  Therefore, in this embodiment, the mirror surface of the mirror piece 612 is inclined (draft angle) so that the angle formed by the incident surface 601 and the light guide surface 602 is 90 ° or more. Thereby, mold release of the light guide 600 can be facilitated, and deformation of the light guide 600 can be suppressed. In this embodiment, the mirror surface of the mirror piece 612 is provided with a groove (not shown) for forming a projection provided on the light guide surface 602, so that the light guide 600 is released. The above configuration is particularly effective to facilitate the above.

  As mentioned above, according to the illuminating device which concerns on a present Example, suppression of the fall of light utilization efficiency and size reduction can be implement | achieved, keeping the positional relationship of a light source and a light guide favorable.

[Example 3]
7A and 7B are schematic views of a main part of a lighting device 7000 according to the third embodiment, in which FIG. 7A is a ZX cross-sectional view, FIG. 7B is a cross-sectional view along AA ′ in FIG. 7 (c) is a cross-sectional view taken along the line BB ′ of FIG. 7 (a). The difference between the present embodiment and the second embodiment is that the light guide 710 has an extending portion 715 extending from the incident surface 711 to the light source 701 side instead of the protrusion. In other words, it is fixed to the holding member 703 via the extended portion 715.

  Specifically, as shown in FIG. 7C, the light guide 710 according to the present embodiment has a light source 701 side with respect to the incident surface 711 in a region where the light emitting unit included in the light source 701 is not arranged. It has the extension part 715 extended in this. In this embodiment, the extending portion 715 is provided with a protruding portion, and the protruding portion is fitted into a perforation (adhesive pool) 704 provided in the holding member 703 to apply the UV adhesive and to perform UV irradiation. Thus, the light guide 710 is fixed to the holding member 703.

  According to this configuration, the light guide surface 714 can be arranged to be inclined with respect to the holding member 703 without providing a protrusion with respect to the light guide surface 714 and without using a fixing member. Thereby, since the opposing area | region 705 can fully be ensured, it can suppress that the light quantity which reaches | attains a to-be-irradiated surface by absorption and scattering in a fixing member falls. In this embodiment, as shown in FIG. 7A, the stability of the light guide 710 is improved by providing a plurality of extending portions 715 to the light guide 710. The effect of the present invention can be obtained even when only one installation portion 715 is provided.

  As mentioned above, according to the illuminating device which concerns on a present Example, suppression of the fall of light utilization efficiency and size reduction can be implement | achieved, keeping the positional relationship of a light source and a light guide favorable.

[Modification]
As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  In Examples 1 and 2, the protrusion provided on the light guide surface has a linear shape extending over the entire region in the arrangement direction of the light emitting units, but is not limited thereto. For example, the protrusions are partially provided in the arrangement direction of the light emitting parts, the direction in which the protrusions extend is set to a direction other than the arrangement direction of the light emitting points, or the protrusions are formed in a shape other than a linear shape such as a dot shape Also good. Further, in each of the embodiments, the protrusion is provided at the end on the incident surface side or the end on the output surface side in the facing region. However, if the stability of the light guide can be maintained, the protrusion is provided. The position where is provided is not limited to this.

  In the first and second embodiments, the fixing member is provided in the entire region of the holding member facing the light guide surface. However, the fixing member is not limited thereto, and is provided only between the edge portion or the protruding portion and the holding member. May be. In Example 3, the extending portion and the holding member are fixed using a UV adhesive, but the present invention is not limited to this, and a double-sided tape, an adhesive, a screw, or the like may be used.

  In Examples 2 and 3, the light guide is configured so that the angle formed between the incident surface and the light guide surface is an obtuse angle. However, as in Example 1, the angle formed between the incident surface and the light guide surface. May be configured to be a right angle, or may be configured such that the angle formed by the exit surface and the entrance surface is an obtuse angle. As in Examples 2 and 3, also in Example 1, the light guide surface is configured to have an angle with respect to the holding member, or the angle formed between the incident surface and the light guide surface is 90 ° or more. You may comprise so that it may become. Furthermore, in Example 3, it is good also as a structure which provides a projection part in a light-guide surface, and improves the stability of a light guide body, attaching the height of an extending part to a Y direction, and ensuring an opposing area | region. You may comprise so that a light guide surface and a holding member may become parallel.

  In each of the above-described embodiments, the configuration in which the light guide has only one light guide surface and one output surface has been described. However, the present invention is not limited to this, and the light guide has a plurality of light guide surfaces or a plurality of output surfaces. It is good also as a structure. For example, like the light guide 810 shown in FIG. 8, the structure which has the 1st light guide surface 814 and the 2nd light guide surface 815, or the structure which has the 1st output surface 812 and the 2nd output surface 813 Etc. can be adopted. According to the light guide 810, light from the incident surface 811, the first light guide surface 814, and the second light guide surface 815 is emitted by the first emission surface 812 and directly guided to the irradiated surface. In addition, the light can be transmitted through the second emission surface 813 and guided to the irradiated surface via another optical member.

DESCRIPTION OF SYMBOLS 1000 Illuminating device 101 Light source 103 Holding member 105 Opposite area 110 Light guide body 111 Incident surface 112 Output surface 114

Claims (13)

An illumination device comprising a light source and a light guide that guides light from the light source to an irradiated surface,
The light source and the light guide are held by a holding member,
The light guide includes an incident surface on which light from the light source is incident, an exit surface from which light from the incident surface exits toward the irradiated surface, and guides light from the incident surface to the exit surface. A light guide surface,
The illuminating device, wherein the light guide surface includes a facing region that faces the holding member via air.   The lighting device according to claim 1, wherein the light source includes a plurality of light emitting units arranged in a first direction. When the length of the holding member is w and the length of the region facing the light guide surface in the holding member is d, in the direction perpendicular to the emission surface of the light source,
d> w / 2
The lighting device according to claim 1, wherein the following condition is satisfied.   The said light guide has the projection part provided in the said light guide surface, and is hold | maintained by the said holding member through this projection part, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. The lighting device according to item.   The lighting device according to claim 4, wherein the light source includes a plurality of light emitting units arranged in a first direction, and the protrusion extends in the first direction.   The lighting device according to claim 4, wherein the protruding portion is provided at an end portion on the emission surface side in the facing region.   The lighting device according to claim 6, wherein the protrusion is further provided at an end portion on the incident surface side in the facing region.   The lighting device according to claim 1, wherein the light guide surface is arranged to have an angle with respect to the holding member.   The illumination device according to claim 8, wherein an angle formed by the holding member and the light guide surface is 5 ° or more.   The lighting device according to claim 8 or 9, wherein the light guide is held by the holding member via an edge portion formed by the incident surface and the light guide surface.   The light guide body has an extending portion extending toward the light source from the incident surface, and is held by the holding member through the extending portion. The lighting device according to any one of 1 to 10.   The illumination device according to any one of claims 1 to 11, wherein an angle formed by the incident surface and the light guide surface is 90 ° or more.   The illumination device according to claim 1, which illuminates a document disposed on the irradiated surface, a light receiving unit that receives light from the document, and light that is received from the document. An image reading apparatus comprising: an image forming unit that leads to

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