JP2012049071A - Optical unit and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical unit and optical elements in which the optical elements are mounted on a comparatively thin shaped light guide plate wherein an optical flux from a light source can be guided efficiently.SOLUTION: By means that adhesive BD is made to stay in a notch 11k installed at an intersection part of an incident face 11a and an emitting face 11b, an LED light source 20 can be arranged at the optimum position against the incident face 11a. In addition, by means that the adhesive BD is made to stay at the end face 11m installed at the intersection part of the emitting face 11b and the slope 11c, it is made possible to increase the amount of light to be guided to the light guide plate 12 by suppressing infiltration of the adhesive BD.

Description

  The present invention relates to an optical unit and an optical element, and more particularly to an optical unit and an optical element that can illuminate a wide range by receiving light from a light source.

  From attempts to reduce carbon dioxide emissions, lighting using LEDs with low power consumption is being developed. On the other hand, by emitting surface light in a wide range from thin and lightweight sheets and panels, etc., it is easy to illuminate without being dazzling, secure an indoor space that is effective as wall-mounted lighting, or install along a curved surface, etc. There is also a demand to improve the freedom of lighting design. However, if energy-saving LEDs or the like are scattered in a sheet or panel, wiring becomes complicated, and there is a problem that the sheet or panel cannot be thinned. On the other hand, there is also an idea that light emitted from an LED is incident from an end face of a sheet or panel and light is emitted from the surface of the sheet or panel. However, when the end face of the sheet or panel is considerably thin relative to the light emitting surface size of the LED, most of the emitted light does not enter from the end face simply by facing the end face of the LED, and is used for effective surface light emission. There is a problem that can not be.

  Here, the present applicant has proposed the light guide technology shown in Patent Documents 1 and 2. According to the technique of Patent Document 1, by integrally forming the light guide plate and the light guide having a groove-like surface shape, light can be efficiently guided from the LED to the light guide plate while reducing light leakage. I am doing so. Further, according to the technique of Patent Document 2, after the optical element having a groove-like surface shape and the light guide plate are molded separately, the tip of the optical element (outgoing surface) and the light guide plate are bonded to reduce light leakage. The light can be efficiently guided from the LED to the light guide plate.

JP 2008-16432 A JP 2008-15467 A

  However, according to the technique disclosed in Patent Document 1, it is difficult to process a mold for forming a complex shape, and it is costly to form a thin sheet-like structure having a large area. In addition, according to the technique disclosed in Patent Document 2, the tip of an optical element that is similarly thinly formed must be bonded to the end face of a thin sheet or panel. However, the thinner the thickness, the insufficient the adhesive strength. Bending may cause peeling at the bonded portion.

  The present invention has been made in view of the problems of the prior art, and based on a new idea, an optical element can be attached to a relatively thin light guide plate to efficiently guide a light beam from a light source. An object is to provide an optical unit and an optical element.

The optical unit according to claim 1, wherein the optical element has an incident surface for receiving light from a light source, and extends in a direction intersecting the incident surface, and is bonded to one surface of the light guide plate. An exit surface for exiting the light incident from the entrance surface to the light guide plate; and a slope extending along the exit surface in a direction intersecting the entrance surface;
The inclined surface is inclined so as to approach the exit surface as it moves away from the entrance surface, and is also a streaky unevenness extending radially along the traveling direction of the light of the light source incident from the entrance surface. It has the part.

  According to the present invention, the optical element has an incident surface for incident light from a light source, and extends in a direction intersecting the incident surface, and is bonded to one surface of the light guide plate and incident from the incident surface. The light exit surface for emitting the light to the light guide plate and a slope extending along the light exit surface in a direction intersecting the light entrance surface, the light exit surface having a relatively large area. By adhering to one surface of the light guide plate, it is possible to secure adhesive strength and suppress separation of the optical element and the light guide plate after adhesion, and light is transmitted to the light guide plate via the optical element. Can be guided effectively. Further, the inclined surface is inclined so as to approach the exit surface as it moves away from the entrance surface, and the streaks extend radially along the traveling direction of the light of the light source incident from the entrance surface. Therefore, the light incident from the incident surface can be effectively guided from the exit surface to the light guide plate using total reflection.

  According to a second aspect of the present invention, in the optical unit according to the first aspect, at least one of the optical element and the light guide plate is formed with a capturing portion that captures an adhesive protruding from an edge of the emission surface. It is characterized by.

  As the adhesion area increases, the amount of adhesive interposed between the optical element and the light guide plate becomes relatively large, so that excess adhesive may protrude from the edge of the emission surface. Problems may occur. Therefore, in the present invention, a capture portion is formed on at least one of the optical element and the light guide plate so as to capture the adhesive protruding from the edge of the emission surface.

  According to a third aspect of the present invention, in the invention of the second aspect, the capture unit is an end surface that is formed to face the incident surface and intersects the emission surface and the inclined surface. And If the capture part is not provided, the exit surface and the slope intersect at an acute angle, and the adhesive protruding from the edge of the exit surface goes around the slope and fills the recesses with streaky irregularities. In some cases, thereby impairing the total reflection condition of the slope. On the other hand, by providing the capture part, it is possible to fasten the adhesive to the end face, and to suppress wrapping around the slope side.

  According to a fourth aspect of the present invention, in the optical unit according to the third aspect, the capture portion includes a protrusion formed on the slope side at the end surface. Thereby, an adhesive agent can be more effectively fastened to the end surface, and it can be prevented that the adhesive wraps around the slope side.

  The optical unit according to a fifth aspect of the present invention is the optical unit according to the second aspect, wherein the capturing portion is a recess or a notch formed at an intersection between the incident surface and the exit surface. If the capture unit is not provided, the adhesive protruding from the mating surface of the light exit surface and the light guide plate is solidified on the incident surface side, and the light source is adjusted to an optimal position with respect to the incident surface. There is a risk of obstacles. On the other hand, by providing the capture part, it is possible to fasten the adhesive to the recess or notch, and to adjust the light source to an optimal position with respect to the incident surface.

  An optical unit according to a sixth aspect is characterized in that, in the invention according to any one of the first to fifth aspects, a minute protrusion is formed on the emission surface. The distance between the light exit surface and the surface of the light guide plate can be adjusted by the minute protrusions, and the amount of adhesive applied between the two can be controlled, so that the amount of adhesive protruding can be minimized. In addition, friction is generated by the protrusions on the light exit surface coming into contact with the surface of the light guide plate, and the positional deviation between the two can be suppressed.

  The optical unit according to claim 7 is characterized in that, in the invention according to any one of claims 1 to 6, a reflective surface is provided on the opposite side of the light exit surface across the light guide plate. To do. With such a reflective surface, light leaking from the light guide plate can be collected and returned to the light guide plate again.

  The optical unit according to claim 8 is the invention according to any one of claims 1 to 7, wherein the streaky uneven portion of the slope is formed by alternately forming a plurality of ridge lines and valley ridge lines. And when a plane that passes through the center of the light source and is orthogonal to the emission surface along a position other than the ridge line of the mountain or the valley is a virtual plane, the light is emitted from the light source and travels along the virtual plane. When the light is incident on the inclined surface, the reflected light has a shape having a directional component that leaves the virtual plane. This is preferable because it easily satisfies the total reflection condition.

  An optical element according to a ninth aspect is used for the optical unit according to the first to eighth aspects.

  In addition, as a raw material of an optical element, transparent things, such as plastics, such as an acryl, glass, and silicon | silicone, are preferable, and also a flame-retardant and heat-resistant material are preferable. In order to ensure good optical performance, the refractive index difference with respect to the light guide plate and the adhesive is desirably 0.5 or less, and more preferably 0.1 or less.

  As the light source, a planar light emitting element such as an LED or an organic EL is preferable. In particular, the surface on the optical element side is preferably flat, and more preferably a surface mount type. The substrate on which the light source is mounted is preferably a high reflection type. The emission color is not limited, but a lens or the like that is not attached is preferable.

  As a material of the light guide plate, plastic, glass, silicon resin, urethane resin, olefin resin, and gel can be used. On the side opposite to the light emitting surface, a diffusing material is preferably printed in the form of dots for light extraction, but may be a protrusion.

  As a material for the adhesive, a transparent adhesive such as UV curable (acrylic), silicon, or gel can be used.

  As a material of the reflector, a material in which silver is formed in a film shape on the surface can be used.

  According to the present invention, it is possible to provide an optical unit and an optical element that can efficiently guide a light beam from a light source by attaching the optical element to a relatively thin light guide plate.

It is sectional drawing of the illuminating device containing the optical unit containing the light-guide plate concerning this Embodiment. Although it is the figure which looked at the optical unit from the upper part, in a slope, the ridgeline of a mountain is shown as a continuous line, and the ridgeline of a valley is shown as a dotted line. It is a perspective view of an optical unit. It is a figure for demonstrating the shape which reduces light leakage and promotes total reflection. It is a figure which shows the end surface shape of an optical element. It is sectional drawing similar to FIG. 1 of the optical unit shown as a comparative example. It is a figure of the optical element concerning the modification of this Embodiment. It is sectional drawing of the optical unit concerning the modification of this Embodiment. It is a partial enlarged view of the optical unit concerning the modification of this Embodiment.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a cross-sectional view of a lighting device including an optical unit including a light guide plate according to the present embodiment, and FIG. 2 is a view of the optical unit as viewed from above. FIG. 3 is a perspective view of the optical unit.

  In FIG. 1, the lighting device includes an optical unit 10, an LED light source 20, a cover 30, and a reflection plate 40. The optical unit 10 includes an optical element 11 and a light guide plate 12. The resin light guide plate 12 is a thin sheet made of transparent plastic, and has a dot-like diffuse reflector 12a printed on the surface on the lower surface 12b side outside the region facing the optical element 11. Become.

  In FIG. 3, the thickness direction of the optical element 11 is the vertical direction (Y direction), the width direction of the optical element 11 is the horizontal direction (X direction), and the direction orthogonal to the X and Y directions is the Z direction. The optical element 11 has a substantially triangular prism shape formed by, for example, a mold, and includes an incident surface 11a, an exit surface 11b, an inclined surface 11c, and side surfaces 11d and 11e. The inclined surface 11c approaches the exit surface 11b as it moves away from the entrance surface 11a. In addition, the slope 11c is provided with a plurality of radial pairs of a pair of elongated inclined surfaces (which are referred to as streak-like uneven portions or prisms) that intersect each other, and an intersecting portion of the pair of inclined surfaces 11g, 11h (this 11i (referred to as a ridgeline of a mountain or a vertex of a prism) extends radially from the incident surface 11a side (preferably from the light emission center of the LED light source 20). Moreover, the intersection of adjacent inclined surfaces 11h and 11g is defined as a valley ridge line 11j.

  The incident surface 11a is disposed in contact with or in proximity to the emitting surface 20a of the LED light source 20 (see FIG. 1). The pitch of one peak is small on the incident surface 11a side, and is formed so as to increase with distance from the incident surface 11a. In addition, as the shape of the inclined surface 11c, the light leakage reduction shape of Unexamined-Japanese-Patent No. 2008-16432 or Unexamined-Japanese-Patent No. 2008-15467 can be used.

  In the present embodiment, the intersection of the entrance surface 11a and the exit surface 11b is cut obliquely to form a notch 11k. Further, the intersection of the emission surface 11b and the slope 11c is cut to form an end surface 11m. As shown in FIG. 5, the end face 11m has a Y-direction interval t2 between the valley twill line and the trough tally line in the Y direction, and t2 ≧ 2 ×. It is preferable that it is t1.

  The emission surface 11b of the optical element 11 is bonded to the upper surface 12c of the light guide plate 12 via an adhesive BD. A cover 30 made of a light shielding material holds the LED light source 20 and covers the outside of the LED light source 20 and the optical element 11. The reflection plate 40 is disposed on the lower surface 12b side of the light guide plate 12 so as to face at least the emission surface 11b. It is preferable to arrange so that an air layer is formed between the light guide plate 12 and the reflecting plate 40 because the ratio of light satisfying the total reflection condition increases.

  As shown in FIG. 2, the length L1 in the Z direction of the optical element 11 is 20 mm, the length W in the X direction of the optical element 11 is 40 mm, and the length L2 of the light guide plate 12 in the Z direction is as follows. = 500-1000 mm. When the length of the light guide plate 12 in the X direction is large, the optical unit 10 may be used side by side so as to connect the side surfaces 11d and 11e of the optical element 11.

  FIG. 1 shows an example of an optical path by a one-dot chain line. The light emitted from the LED light source 20 is totally reflected by the inclined surface 11c (some are emitted from the inclined surface 11c and thus shielded by the cover 30) and emitted from the emitting surface 11b. After being incident on the light guide plate 12 and totally reflected by the lower surface 12b (a part is emitted from the lower surface 12b but reflected by the reflecting surface of the reflecting plate 40), the light is incident again from the emitting surface 11b and is inclined. 11c is totally reflected, exits from the exit surface 11b, enters the light guide plate 12, proceeds while being totally reflected on the upper and lower surfaces of the light guide plate 12, and when part of the light is reflected by the diffuse reflector 12a on the lower surface 12b, By emitting light from the upper surface 12c, surface light emission is performed. That is, most of the light emitted from the LED light source 20 is injected into the thickness of the thin light guide plate 12 while repeating total reflection on the inclined surface 11 c of the optical element 11 and the lower surface 12 b of the light guide plate 12. Will be transmitted.

  Here, the reason why total reflection occurs on the inclined surface 11c of the optical element 11 will be described. FIG. 4 is a diagram for explaining a shape that reduces light leakage and promotes total reflection. In FIG. 4, a YZ plane (imaginary plane) is defined as a plane that passes through the center of the LED light source (not shown) and is orthogonal to the emission surface 11b. Here, it is assumed that the slope 11 </ b> C ′ indicated by the dotted line is inclined so as to approach the lower surface 12 b of the light guide plate 12 as it moves away from the incident surface side (that is, only in the Z direction). In such a case, the light emitted from the front edge of the YZ plane and traveling along the YZ plane is reflected by the slope 11C ′ at the point A as indicated by the dotted arrow because the total reflection condition is satisfied while the incident angle is small. Subsequently, the light is reflected by the exit surface 11b at the point B ′ and does not leave the YZ plane even after the reflection. However, when the inclined surface 11C 'is inclined so as to approach the emission surface 11b in the light traveling direction, the incident angle θ2' at the point B becomes larger than the incident angle θ1 at the point A. Accordingly, if any incident angle exceeds the threshold value during repeated reflection, the total reflection condition is lost, and light may leak to the outside through the inclined surface 11C 'or the lower surface 12b.

  Therefore, as a shape that reduces light leakage and promotes total reflection, a configuration in which an inclined surface 11C that is inclined not only in the light traveling direction but also on the right side (that is, in the Z direction and the X direction) is provided. Think (see solid line). In the example of FIG. 4, it is assumed that the YZ plane intersects at the intersection of the slopes 11C 'and 11C. According to such a configuration, the light emitted from the front edge of the YZ plane and traveling along the YZ plane is reflected by the slope 11C at the point A as shown by the solid line arrow, and is subsequently different from the point B ′. Although reflected by the lower surface 12b at B, the point B does not exist in the YZ plane. In other words, the light reflected by the inclined surface 11C at the point A has an X-direction component orthogonal to the YZ plane, proceeds in a direction away from the YZ plane, and enters a point B far from the point B ′. . Accordingly, when the slope 11C ′ is used and the slope 11C is used, if the incident angle θ1 at the point A is the same, the incident angle θ2 at the point B is greater than the incident angle θ2 ′ at the point B ′. As a result, when the slope 11C is used, the possibility of satisfying the total reflection condition is increased even when reflection is repeated as compared with the case where the slope 11C ′ is used.

  However, this effect is not limited to rays incident on the inclined surface 11C along the YZ plane or along a plane parallel to the YZ plane, that is, incident rays having only components in the Y direction and the Z direction. Similar effects can be obtained with respect to incident rays having components in the X direction in addition to the Y and Z directions. That is, a part or all of the Y direction component of the incident light beam is converted into the X direction or the Z direction by the inclined surface 11C, so that the possibility that the light beam satisfies the total reflection condition is increased.

  In this way, the shape that reduces light leakage and promotes total reflection is such that either the inclined surface 11c of the optical element 11 or the light guide plate 12 has the lower surface 12b in the vertical direction (height direction) on the side surface 11d or 11e side. The function can be exhibited only by inclining uniformly in the direction of narrowing the width, but the height of the optical element 11 increases. Therefore, in the present embodiment, as shown in FIG. 3, a part of the inclined surface 11c is deformed, and a plurality of pairs of intersecting long and slanted inclined surfaces (which are referred to as streaky irregularities or prisms) 11g and 11h are provided. In addition, since the intersecting portion 11i (referred to as the apex of the prism) 11i of the pair of inclined surfaces 11g and 11h extends radially, the thickness of the optical element 11 can be reduced. Incidentally, in FIG. 1, the height of the LED light source is 1.5 mm, the maximum thickness of the optical element 11 in the Y direction is 1 mm, and the thickness of the light guide plate 12 is 0.5 mm. Thus, by reducing the thickness of the light guide plate 12, light can be emitted while being wound around a cylinder or suspended like a curtain. Also, when not in use, it can be rolled up and stored, making it easy to use.

  When the optical unit is manufactured, the light emitting surface of the optical element 11 is bonded to the surface of the light guide plate 12, but since the bonding area is large, it can be firmly bonded. However, since the amount of the adhesive used at the time of bonding increases, the adhesive BD may protrude. More specifically, in FIG. 6 shown as a comparative example, in a state where the incident surface 11a and the exit surface 11b intersect at a right angle, the adhesive BD applied between the exit surface 11b and the light guide plate 12 protrudes. As this solidifies, the light incident efficiency from the part where the adhesive protrudes is lowered, and it becomes an obstacle when adjusting the LED light source 20 to an optimum position for taking in light to the incident surface 11a. There is a fear. On the other hand, according to the present embodiment, as shown in FIG. 1, the adhesive BD is fastened to the notch 11k provided at the intersection of the entrance surface 11a and the exit surface 11b, so that the entrance surface 11a The LED light source 20 can be arranged at an optimal position, and the light emitted from the LED light source 20 can be taken into the optical member 11 without loss. In addition, by preventing the adhesive BD from rising to the LED light source 20 side, unnecessary light scattering can be suppressed.

  On the other hand, in FIG. 6 shown as a comparative example, in a state where the exit surface 11b and the inclined surface 11c intersect at an acute angle, the adhesive BD applied between the exit surface 11b and the light guide plate 12 protrudes and wraps around the inclined surface 11c side. As a result, the streak-like grooves are filled, the total reflection performance is deteriorated, the amount of light guided to the light guide plate 12 is reduced, and the scattering effect is generated by the rise of the adhesive BD, and the light guided to the light guide plate 12 There is a risk that the amount of will decrease. On the other hand, according to the present embodiment, as shown in FIG. 1, the adhesive BD is restrained from being wrapped around the end surface 11m provided at the intersection of the emission surface 11b and the inclined surface 11c. As a result, the amount of light guided to the light guide plate 12 can be increased.

  FIG. 7 is a cross-sectional view of an optical unit according to a modification of the present embodiment. In the present modification, a hook-shaped convex portion 11n is formed on the slope 11c side of the end face 11m provided at the intersection of the emission surface 11b and the slope 11c. Thus, by forming the convex part 11n, the effect which fastens adhesive BD to the end surface 11m is exhibited effectively, and wraparound of adhesive BD can be suppressed. Such convex portions 11n can be formed by molding a mold, but may be formed by intentionally generating burrs, for example.

  FIG. 8 is a cross-sectional view of an optical unit according to another modification of the present embodiment. In this modification, instead of (or in addition to) providing an end surface at the intersection with the exit surface 11b slope 11c of the optical element 11, a groove shape is formed on the upper surface 11c of the light guide plate 12 in the vicinity of the edge of the exit surface 11b. A recess 12d is formed. By fastening the adhesive BD in the concave portion 12d, the adhesive BD can be prevented from wrapping around and the amount of light guided to the light guide plate 12 can be increased. Further, in this modification, instead of (or in addition to) providing a notch at the intersection between the incident surface 11a and the exit surface 11b of the optical element 11, a guide is provided near the edge of the exit surface 11b on the entrance surface 11a side. A notch 12 e is formed at the edge of the optical plate 12. By fastening the adhesive BD to the notch 12e, the LED light source 20 can be arranged at an optimal position with respect to the incident surface 11a.

  FIG. 9 is a partially enlarged view of an optical unit according to another modification of the present embodiment. A minute protrusion 11p is formed on the emission surface 11b of the optical element 11. The minute protrusion 11p can adjust the distance between the exit surface 11b and the upper surface 12c of the light guide plate 12, and the amount of adhesive BD applied between the two can be controlled, so that the amount of adhesive BD that protrudes can be minimized. Can do. Further, the protrusion 11p of the emission surface 11b abuts on the upper surface 1c of the light guide plate 12, friction is generated, and displacement between the two can be suppressed.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. For example, the number of peaks and valleys on the slope is arbitrary.

DESCRIPTION OF SYMBOLS 10 Optical unit 11 Optical element 11a Incident surface 11b Output surface 11c Inclined surface 11d, 11f Side surface 11g Inclined surface 11h Inclined surface 11i Mountain ridge line 11j Valley ridge line 11k Notch 11m End surface 11n Protruding part 11p Minute protrusion 12 Light guide plate 12a Dot-shaped reflection material 12a 12b Lower surface 12c Upper surface 12d Recess 12e Notch 20 LED light source 20a Emission surface 30 Cover 40 Reflector BD Adhesive

Claims (9)

In an optical unit having an optical element and a light guide plate,
The optical element includes an incident surface for incident light from a light source, and extends in a direction intersecting the incident surface, is bonded to one surface of the light guide plate, and transmits the light incident from the incident surface. An exit surface for exiting and an inclined surface extending in the direction intersecting the entrance surface and extending along the exit surface,
The inclined surface is inclined so as to approach the exit surface as it moves away from the entrance surface, and is a streak-like unevenness extending radially along the traveling direction of the light of the light source incident from the entrance surface. An optical unit comprising a portion.   2. The optical unit according to claim 1, wherein at least one of the optical element and the light guide plate is formed with a capture unit that captures an adhesive protruding from an edge of the emission surface.   The optical unit according to claim 2, wherein the capturing unit is an end surface that is formed to face the incident surface and intersects the emitting surface and the inclined surface.   The optical unit according to claim 3, wherein the capturing unit includes a protrusion formed on the inclined surface side at the end surface.   The optical unit according to claim 2, wherein the capturing unit is a recess or a notch formed at an intersection between the incident surface and the exit surface.   6. The optical unit according to claim 1, wherein a minute protrusion is formed on the emission surface.   The optical unit according to claim 1, wherein a reflective surface is provided on the opposite side of the light exit surface with the light guide plate interposed therebetween.   The streaky irregularities of the slope form a plurality of mountain ridge lines and valley ridge lines alternately, and pass through the center of the light source along positions other than the mountain ridge lines or the valley ridge lines. When a plane orthogonal to the emission surface is a virtual plane, when light emitted from the light source and traveling along the virtual plane enters the inclined surface, a direction component such that the reflected light is separated from the virtual plane. The optical unit according to claim 1, wherein the optical unit has a shape.   An optical element used for the optical unit according to claim 1.

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