JP2008187065A - Light source device - Google Patents

Abstract

Provided is a light source device having an electrowetting effect that can stably obtain desired light distribution characteristics and can be easily incorporated into a device.
A light source device according to the present invention includes a conductive first liquid, an insulating second liquid having a refractive index different from that of the first liquid, and first and second liquids. A liquid chamber to be stored, voltage applying means for changing the shape of the interface 13A between the first and second liquids, and a light emitter 20 installed in the liquid chamber are provided. By installing the light emitting body 20 in the liquid chamber, the lens element 13 and the light source can be integrated, whereby the entire light source device can be reduced in size and thickness. In addition, since the light source and the lens element can be integratedly designed, manufactured, and incorporated into a device, desired light distribution characteristics can be stably obtained.
[Selection] Figure 1

Description

  The present invention relates to a light source device utilizing an electrowetting effect (electrocapillarity).

  In recent years, development of optical elements (electrowetting devices) using the electrowetting effect has been promoted. The electrowetting effect is a phenomenon in which when a voltage is applied between a conductive liquid and an electrode, the energy of the solid-liquid interface between the electrode surface and the liquid changes, and the shape of the liquid surface changes.

  For example, Patent Literature 1 below discloses a camera strobe device that uses an electrowetting effect. This strobe device includes a light source and a lens array in which individual lenses are formed with an interface shape between an insulating liquid and a conductive liquid, and each lens shape of the lens array is formed using an electrowetting effect. By controlling electrically, the light distribution angle of the light source light irradiated from the back surface is arbitrarily controlled.

JP 2000-356708 A

  However, the strobe device described in Patent Document 1 has a problem that the entire strobe device cannot be reduced in size and thickness because the lens array is configured separately from the light source. In addition, since the geometric positional relationship between the lens array and the light source affects the optical characteristics of the device, it is difficult to stably obtain desired light distribution characteristics due to variations in the position between the two.

  In addition, since it is necessary to optimize the installation position of the lens array and the individual lens characteristics in accordance with the form, size, light emission characteristics, etc. of the light source used, the design of the device becomes complicated. Furthermore, since the light source and the lens array have different configurations, there is a problem that the number of assembling work steps for an optical device such as a camera is increased.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a light source device having an electrowetting effect that can stably obtain desired light distribution characteristics and can be easily incorporated into a device.

  In solving the above-described problems, the light source device of the present invention includes a conductive first liquid, an insulating second liquid having a refractive index different from that of the first liquid, and the first and second liquids. It is characterized by comprising a liquid chamber to be stored, voltage applying means for changing the shape of the interface between the first and second liquids, and a light emitter installed in the liquid chamber.

  The first liquid and the second liquid are contained in the liquid chamber without being mixed with each other, and constitute a lens element that forms a lens surface at the interface between the two liquids. In this lens element, the shape of the lens at the interface is electrically controlled using an electrowetting effect between the conductive liquid and the liquid chamber inner surface.

  In the light source device of the present invention, the lens element and the light source are integrated by installing a light emitter in a liquid chamber that accommodates the first and second liquids. Thereby, size reduction and thickness reduction of the whole light source device are realizable. In addition, since the light source and the lens element can be integratedly designed, manufactured, and incorporated into a device, desired light distribution characteristics can be stably obtained.

  As the light emitter, a semiconductor light emitting element such as a light emitting diode or a semiconductor laser is suitable. Other than this, a linear light source such as a xenon tube, a lamp light source, or the like is applicable.

  The voltage applying means applies a predetermined voltage between the conductive first liquid and the liquid chamber inner surface. An electrode layer and a water-repellent insulating film covering the surface are formed on the inner surface of the liquid chamber. In a state where no voltage is applied, a predetermined interface shape determined by the surface tensions of the first and second liquids is maintained, but the contact angle of the first liquid with respect to the liquid chamber surface changes due to application of the drive voltage. Therefore, by appropriately adjusting the magnitude of the driving voltage, the interface shape can be reversibly changed, and arbitrary light distribution control of the light emitted from the light emitter can be performed.

  At this time, it is possible to improve the light use efficiency, the light distribution controllability, and the like by forming the liquid chamber with a reflector (reflector) that internally reflects the light of the light emitter. In this case, it is preferable to form the inner surface of the reflector in a predetermined curved shape so that the reflected light has directivity. On the other hand, instead of the reflector, by providing a lens layer that converts the emitted light of the light emitter into parallel light between the interface between the first and second liquids and the light emitter, the same effect as described above can be obtained. Obtainable.

  Further, by arranging a plurality of liquid chambers in an array, a lens array integrated with the light source can be configured. Here, when a point light source such as a semiconductor light emitting element is used as the light emitter, the light emitters can be individually installed in a plurality of liquid chambers. On the other hand, when a linear light source such as a fluorescent tube is used as the light emitter, the light emitter can be installed in common in a plurality of adjacent liquid chambers.

  As described above, according to the light source device of the present invention, since the light source and the lens element are integrally formed, the entire light source device can be reduced in size and thickness. In addition, since the light source and the lens element can be integratedly designed, manufactured, and incorporated into a device, desired light distribution characteristics can be stably obtained.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments, and various modifications can be made based on the technical idea of the present invention.

(First embodiment)
FIG. 1 is a side sectional view showing a schematic configuration of a light source device 1 according to a first embodiment of the present invention. In the light source device 1 of the present embodiment, a conductive first liquid 11 and an insulating second liquid 12 are accommodated in a liquid chamber formed inside a hermetic container 19. A lens element 13 that forms a lens surface is formed by an interface 13A between the liquid 11 and the second liquid 12. A light emitter 20 is installed on the bottom of the container 19 that houses the lens element 13.

  As the first liquid 11, a transparent liquid having conductivity is used. For example, water, an electrolytic solution (aqueous solution of an electrolyte such as potassium chloride, sodium chloride, or lithium chloride), methyl alcohol having a low molecular weight, ethyl alcohol, or the like. Polar liquids such as alcohols and room temperature molten salts (ionic liquids) can be used.

  As the second liquid 12, a transparent liquid having insulating properties is used. For example, a hydrocarbon-based material such as decane, dodecane, hexadecane, or undecane, a nonpolar solvent such as silicone oil or a fluorine-based material is used. be able to. In the present embodiment, the surface tension of the second liquid 12 is smaller than the surface tension of the first liquid 11.

  The first and second liquids 11 and 12 are selected from materials having different refractive indexes and capable of existing without being mixed with each other. Specifically, in the present embodiment, an aqueous lithium chloride solution (concentration 3.66 wt%, refractive index 1.34) is used as the first liquid 11, and silicone oil (TSF437 manufactured by GE Toshiba Silicone Co., Ltd.) is used as the second liquid 12. , Refractive index 1.49) is used. The first and second liquids 11 and 12 preferably have the same specific gravity. Moreover, the 1st, 2nd liquids 11 and 12 may be colored as needed.

  Next, the container 19 includes a housing 14 that is a container body, a substrate 15 that is liquid-tightly fixed to the lower end of the housing 14, and a transparent lid 16 that is liquid-tightly fixed to the upper end of the housing 14. ing.

  The housing 14 is formed in a cylindrical shape or a rectangular tube shape, and an internal space is formed as a liquid chamber that houses the lens element 13. An electrode layer 17 and an insulating film 18 covering the electrode layer 17 are formed on the inner surface of the housing 14. In the present embodiment, the electrode layer 17 is formed over substantially the entire inner surface of the housing 14, but it is sufficient that the electrode layer 17 is formed at least in a region where the lens surface 13 </ b> A of the lens element 13 moves up and down. The electrode layer 17 and the first liquid 11 are connected to an external voltage source (not shown) via wirings 21 and 22, respectively. The electrode layer 17, the wirings 22 and 22, and the voltage source constitute “voltage application means” of the present invention.

  The insulating film 18 is used for electrical insulation between the electrode layer 17 and the first liquid 11, and is formed of a water-repellent material or has a surface subjected to water-repellent treatment. The insulating film 18 is formed using an appropriate surface coating method such as a CVD method, a dipping method, or an electrodeposition method. As a constituent material of the insulating film 18, for example, an organic material such as polyparaxylylene or PTFE (polytetrafluoroethylene), or a metal oxide such as tantalum oxide or titanium oxide can be used.

  The light emitter 20 is composed of a light emitting diode (LED), but may be composed of another semiconductor light emitting element such as a laser diode (LD). The light emitter 20 is mounted on the substrate 15 and installed in the liquid chamber. The substrate 15 is configured as a wiring substrate and is electrically connected to the light emitter 20. 1 is a type in which one terminal is formed on the surface side, and is connected to an external power source via a bonding wire and a wiring 23 including a wiring layer of the substrate 14. However, of course, a type of light emitter in which all terminals are formed on the back side may be used.

  The light emitting body 20 is covered with the insulating second liquid 12 to ensure electrical insulation between the light emitting body 20 and the first liquid. Further, the container 19 liquid-tightly seals the first and second liquids 11 and 12 by interposing an adhesive member such as an adhesive between the housing 14 and the substrate 15 and the lid body 16. .

  In the light source device 1 of the present embodiment configured as described above, the light emitted from the light emitter 20 is emitted to the outside through the lens element 13 and the lid body 16. The shape of the interface 13A between the first liquid 11 and the second liquid 12 is a spherical surface or an aspheric surface, and the curvature thereof changes according to the magnitude of the drive voltage supplied from the external voltage source. The interface 13A constitutes a lens surface having a lens power corresponding to the difference in refractive index between the first liquid 11 and the second liquid 12. Therefore, by adjusting the magnitude of the drive voltage applied between the first liquid 11 and the electrode layer 17, the light distribution angle (or focal length) of the light emitted from the light emitter 20 can be changed. It becomes possible.

  Specifically, when no voltage is applied, the interface 13A between the first liquid 11 and the second liquid 12 is balanced by a concave lens shape convex toward the light emitter 20, as indicated by a solid line in FIG. Therefore, when the refractive index of the second liquid 12 is larger than the refractive index of the first liquid 11, the lens element 13 having the interface 13A having the shape diffuses and emits the light L of the light emitter 20.

  On the other hand, when a voltage starts to be applied between the first liquid 11 and the electrode layer 17, the wettability of the first liquid 11 with respect to the insulating film 18 on the inner surface of the liquid chamber (container 19) increases due to the electrowetting effect. As a result, the curvature of the interface 13A gradually decreases. When the drive voltage increases beyond a certain level, the interface 13A becomes a flat surface as shown by a one-dot chain line in FIG. In this case, the light L of the light emitter 20 is emitted linearly with almost no lens effect at the interface 13A. If the driving voltage is further increased from this state, the interface 13A has a convex lens shape convex toward the lid 16 side, and the light from the light emitter is converged and emitted.

  As described above, according to the present embodiment, the lens surface 13A of the lens element 13 is reversibly changed by adjusting the magnitude of the drive voltage applied between the first liquid 11 and the electrode layer 17. Therefore, the outgoing light distribution angle of the light emitted from the light emitter 20 can be changed electrically. This makes it possible to arbitrarily adjust the intensity and irradiation range of the light emitted from the light source device 1, and is suitably used as a small light source device such as a penlight, a laser pointer, or a laser light source for an optical pickup device. .

  Further, according to the present embodiment, since the lens element 13 and the light emitter (light source) 20 are integrally configured, it is possible to reduce the size and thickness of the entire light source device, and to the equipment. No complicated alignment work between the light source and the lens element is required when assembling the lens.

  Furthermore, according to the present embodiment, since the lens element 13 and the light emitter (light source) 20 are integrally formed, the light source and the lens element can be integrally designed, manufactured, and incorporated into a device. Thus, desired light distribution characteristics can be stably obtained. In particular, a small light distribution angle variable light source device using a micro component such as a semiconductor light emitting element as the light emitter 20 can be manufactured with high accuracy and ease.

(Second Embodiment)
FIG. 2 is a side sectional view showing a schematic configuration of the light source device 2 according to the second embodiment of the present invention. In the figure, portions corresponding to those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  The light source device 2 of the present embodiment constitutes a lens array in which the above-described light source devices 1 are arranged in a plurality of arrays. The arrangement direction is not limited to a one-dimensional direction, and may be a two-dimensional direction. The individual lens elements 13 have the same configuration and are installed on the substrate 15 in common. The interior of the container 19 is partitioned into a plurality of liquid chambers by a partition wall 21, and the lens elements 13 are accommodated in the individual liquid chambers, and the light emitters 20 are individually installed. Further, the upper wall of the container 19 is formed of a transparent lid 16 common to a plurality of liquid chambers, and constitutes an emission surface of light emitted from each light emitting body 20.

  In the light source device 2 of the present embodiment configured as described above, a lens array in which the lens elements 13 including the light emitters 20 are arranged in a plurality of arrays is configured, and thus the first embodiment described above. Compared to the above, the irradiation area of the light source light is widened, and for example, it can be suitably implemented as a strobe device of a camera. The lens elements are not limited to drive control in common, but can be controlled individually.

(Third embodiment)
3 and 4 are side sectional views showing a schematic configuration of the light source device 3 according to the third embodiment of the present invention. FIG. 3 shows a diffuse emission mode of the light source light L, and FIG. The parallel emission mode is shown. In the figure, portions corresponding to those in the first and second embodiments described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  The light source device 3 of the present embodiment is different from the above-described second embodiment in that a container that accommodates each lens element 13 is configured by a reflector (reflector) 22. The inner surface of the reflector 22 is formed in a predetermined curved shape so as to reflect the light emitted from the light emitter 20 in the direction of the lid 16 with directivity. An electrode layer 17 is formed on the inner surface of the reflector 22, and an insulating film 18 that covers the electrode layer 17 is formed. The light emitter 20 is installed directly on the inner bottom of the reflector 22 and is electrically connected to an external power supply circuit through the reflector 22.

  In the light source device 3 of the present embodiment configured as described above, as in the second embodiment described above, a lens array in which the lens elements 13 including the light emitters 20 are arranged in a plurality of arrays is configured. Therefore, the irradiation area of the light source light L is wider than that in the first embodiment described above, and can be suitably implemented as, for example, a camera strobe device or an automobile headlamp.

  In particular, according to the present embodiment, since the container that accommodates the lens element 13 is constituted by the reflector 22, it is possible to effectively utilize the light generated by the light emitter 20, and improve the illuminance as a light source. be able to. Further, since the light emitted from the light emitter 20 by the reflector 22 rises in the front direction (upward in the figure), the voltage is driven when the lens element 13 has a flat interface 13A as shown in FIG. The parallelization of the emitted light becomes easy, and the light distribution controllability can be improved.

(Fourth embodiment)
5 and 6 are side sectional views showing a schematic configuration of the light source device 4 according to the fourth embodiment of the present invention. FIG. 5 shows a diffuse emission mode of the light source light L, and FIG. The parallel emission mode of the light L is shown. In the figure, portions corresponding to those in the first and second embodiments described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the light source device 4 of the present embodiment, a lens layer 23 that converts the emitted light of the light emitter 20 into parallel light is provided inside each liquid chamber that houses the lens element 13. The lens layer 23 is disposed between the light emitting body 20 and the interface 13A between the first and second liquids 11 and 12, and is formed of a transparent insulating resin layer that molds the light emitting body 20 on the substrate 15. Yes. Further, the resin material constituting the lens layer 23 is a material having a refractive index different from that of the second liquid 12.

  With such a configuration, the light emitted from the light emitter 20 can be efficiently launched in the front direction by the lens layer 23, so that the light use efficiency and the light distribution controllability can be improved as in the third embodiment. It is possible to improve.

  In addition, according to the present embodiment, since the light emitter 20 is sealed by the lens layer 23, the light emitter 20 even if the upper and lower arrangement relationships of the first liquid 11 and the second liquid 12 are reversed. Therefore, it is possible to secure the electrical insulation of the lens element 13 and to improve the design freedom of the lens element 13.

(Fifth embodiment)
7 and 8 are side sectional views showing a schematic configuration of a light source device 5 according to a fifth embodiment of the present invention, FIG. 7 is a side sectional view for explaining the configuration of the light source device 5, and FIG. 8 is a light source device. FIG. 6 is a side sectional view for explaining the operation of 5. In the figure, portions corresponding to those in the first and third embodiments described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  The light source device 5 of the present embodiment has a configuration in which the lens element 13 is accommodated inside a reflector 22 configured as a container, and the light emitter 24 is installed at the bottom of the container 22. In the present embodiment, the light emitter 24 is composed of a linear light source such as a xenon tube.

  In the light source device 5 of the present embodiment, light emitted from the periphery of the light emitter 24 can be raised in the front direction by the reflector 22, so that the light use efficiency can be improved and at the same time electrowetting. The light distribution controllability by the lens element 13 utilizing the effect can be enhanced. FIG. 8A shows the diffusion emission mode of the light source light L when the interface 13A has a concave lens shape (when no voltage is applied), and FIG. 8B shows the parallel emission mode of the light source light L when the interface 13A is planar (when voltage is applied). ). In addition, the convergence (condensation) emission mode of the light source light L can be realized by further increasing the drive voltage.

  Furthermore, a lens array can be configured by arranging a plurality of light source devices 5 in an array. In this case, although not shown, the light emitter 24 can be configured as a light emitter that extends in the arrangement direction of the light source devices 5 and is common to a plurality of light source devices adjacent in the arrangement direction.

It is a sectional side view which shows schematic structure of the light source device by the 1st Embodiment of this invention. It is a sectional side view which shows schematic structure of the light source device by the 2nd Embodiment of this invention. It is a sectional side view explaining schematic structure and one effect | action of the light source device by the 3rd Embodiment of this invention. It is a sectional side view explaining the other effect | action of the light source device by the 3rd Embodiment of this invention. It is a sectional side view explaining schematic structure and one effect | action of the light source device by the 4th Embodiment of this invention. It is a sectional side view explaining the other effect | action of the light source device by the 4th Embodiment of this invention. It is a sectional side view which shows schematic structure of the light source device by the 5th Embodiment of this invention. It is a sectional side view explaining the effect | action of the light source device by the 5th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 2, 3, 4, 5 ... Light source device, 11 ... 1st liquid, 12 ... 2nd liquid, 13 ... Lens element, 13A ... Interface (lens surface), 14 ... Housing, 15 ... Substrate, 16 ... Lid, 17 ... electrode layer, 18 ... insulating film, 19 ... container, 20, 24 ... light emitter, 21 ... partition wall, 22 ... reflector, 23 ... lens layer, L ... light source light

Claims (6)

A conductive first liquid;
An insulating second liquid having a refractive index different from that of the first liquid;
A liquid chamber containing the first and second liquids;
Voltage applying means for changing the shape of the interface between the first and second liquids;
A light emitting device installed in the liquid chamber. The light source device according to claim 1, wherein the light emitter is a semiconductor light emitting element. The light source device according to claim 1, wherein the liquid chamber is formed of a reflector that internally reflects light emitted from the light emitter. The light source device according to claim 3, wherein the reflector has a curved shape that imparts directivity to the light reflected by the inner surface thereof. 2. The light source according to claim 1, wherein a lens layer for converting emitted light of the light emitter into parallel light is provided between the interface between the first and second liquids and the light emitter. apparatus. A plurality of the liquid chambers are arranged in an array,
The light source device according to claim 1, wherein the light emitters are individually installed in the plurality of liquid chambers.

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