Patent Application
20140240956
1. Field of the Invention
The present invention relates to a light source device.
2. Description of the Related Art
In general, there is known a light source device that emits primary light from a primary light source, leads this primary light to a light conversion unit through an optical fiber, converts characteristics of the primary light in this light conversion unit, and emits the converted light therefrom as illumination light. For example, Jpn. Pat. Appln. KOKAI Publication No. 2007-220326 discloses a technology concerning a light source device including an excitation light source which is a primary light source that emits excitation light as primary light and a fluorescent material as a light conversion unit. In the light source device disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2007-220326, the excitation light emitted from the excitation light source is led through an optical fiber and enters the fluorescent material. A wave length of the led excitation light is converted, and the fluorescent material radiates fluorescence. This light source device emits the radiated fluorescence and the excitation light led from the excitation light source as the illumination light.
In the above-described light source device, heat is generated in the light conversion unit with the light conversion. To stably operate the light source device, the generated heat needs to be removed from the light conversion unit. In this case, the light conversion unit should be appropriately cooled so that a surface temperature of the light source device will not reach a high temperature beyond an allowable temperature that is set in accordance with the device.
It is an object of the present invention to provide a light source device having a mechanism that cools a light conversion unit while setting a surface temperature of an in-use device to an allowable temperature or less.
According to an aspect of the present invention, a light source device includes: a light conversion unit configured to emit illumination light; a heat radiation unit configured to radiate heat generated in the light conversion unit; and a heat storage unit which is thermally connected to the light conversion unit or the heat radiation unit and configured to store the heat.
According to the present invention, it is possible to provide the light source device that can cool the light conversion unit while setting a surface temperature of an in-use device to an allowable temperature or less since the heat storage unit that stores heat is provided.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.
A first embodiment according to the present invention will now be described with reference to the drawings.
The primary light source 110 emits primary light. As the primary light, it is possible to use various kinds of light in accordance with the later-described light conversion element 130. The primary light emitted from the primary light source 110 is led toward the light conversion element 130 through the optical fiber 120. That is, the optical fiber 120 is connected to the primary light source 110 and the light conversion element 130.
The light conversion element 130 receives the primary light led through the optical fiber 120 and emits secondary light as illumination light emitted from the light source device 100. For example, the light conversion element 130 may include a fluorescent material that generates florescence using the primary light as excitation light. Furthermore, for example, the light conversion element 130 may include an element having a light diffusing function of enlarging a spread angle of the primary light and emitting this light as safe secondary light, when the primary light is a laser beam. Moreover, for example, when the primary light is a laser beam, the light conversion element 130 may include an element having a function of converting a phase of the laser beam to reduce coherence and avoid generation of speckles.
The heat storage member 140 has a heat storing function. For example, the heat storage member 140 may include a sensible heat storage member using water, a metal having high specific heat, or the like. Additionally, the heat storage member 140 may include a latent heat storage material using endotherm at the time of a phase change. In particular, the heat storage member 140 may include heat storage capsules or the like obtained by forming microcapsules of the latent heat storage material. The heat storage capsule has a structure in which the latent heat storage material such as an aliphatic hydrocarbon compound, alcohol, ester, or an aliphatic acid is contained in a resin film having a diameter of, e.g., several μm. The heat storage member 140 is thermally connected to the light conversion element 130 and the heat radiation member 150. Therefore, the heat storage member 140 stores part of the heat generated by the light conversion element 130 and transfers that heat to the heat radiation member 150.
The heat radiation member 150 is a member that radiates heat to an exterior environment from the light source device 100. The heat generated by the light conversion element 130 is transferred to the heat radiation member 150 via the heat storage member 140 and radiated from the heat radiation member 150. The exterior or the like of the light source device 100 may be allowed to function as the heat radiation member 150. It is to be noted that, in
An operation of the light source device 100 according to this embodiment will now be described. For example, the primary light source 110 is assumed to be a laser beam source that emits a laser beam. The primary light source 110 emits a laser beam as primary light. The emitted laser beam enters the optical fiber 120. This laser beam travels in the optical fiber 120 and reaches the light conversion element 130.
For example, the light conversion element 130 is assumed to contain a fluorescent material that absorbs the laser beam, which is the primary light, as excitation light and generates fluorescence. In this case, the light conversion element 130 absorbs the laser beam led through the optical fiber 120 and radiates the excitation light. That is, the wavelength of the laser beam is converted by the light conversion element 130. The fluorescence that was subjected to this wavelength conversion and the excitation light that was not subjected to the wavelength conversion are allowed to exit from the distal end of the light source device 100 as illumination light.
The light conversion element 130 generates heat at the time of performing the wavelength conversion. The heat generated from this light conversion element 130 is transferred to the heat storage member 140. The heat storage member 140 stores part of the heat transferred from the light conversion element 130. When the heat storage member 140 includes a sensible heat storage material such as water or a metal having high specific heat, part of the heat is stored in the sensible heat storage material as sensible heat. Further, when the heat storage member 140 includes heat storage capsules, part of the heat is absorbed by the heat storage capsules as latent heat. The heat that is not stored in the heat storage member 140 is transferred to the heat radiation member 150. The heat radiation member 150 having the heat transferred from the heat storage member 140 discharges part of the heat to the outside of the light source device 100.
As described above, for example, the light conversion element 130 functions as a light conversion unit that emits the illumination light. For example, the heat radiation member 150 functions as a heat radiation unit that radiates heat generated in the light conversion unit to the outside. For example, the heat storage member 140 functions as a heat storage unit that is thermally connected to the light conversion unit or the heat radiation unit and stores heat.
To explain the effect of this embodiment,
For example, to avoid damage to the light source device 100 and/or safely use the light source device 100, the need for providing an allowable limit to the surface temperature is assumed. This allowable temperature is indicated by a broken line in
When the allowable temperature is set to a temperature at which a failure or deterioration in each unit is not caused or a temperature at which discomfort or the like is not given to a user, it is possible to avoid a failure of the device or prevent discomfort from being given to a user. It is to be noted that, in the case of using a latent heat storage material for the heat storage member 140, when a heat storage temperature of the latent heat storage material is set to be lower than the allowable temperature, the effect can be obtained in particular.
In this embodiment, the heat storage member 140 is installed between the heat radiation member 150 and the light conversion element 130, but it may be installed in any region as long as heat from the light conversion element 130 can be transferred to this region. Additionally, the heat storage member 140 may be incorporated in the heat radiation member 150. Further, the heat radiation member 150 may be made of a material having relatively high specific heat. Furthermore, it is possible to adopt a configuration that heat is discharged from the heat storage member 140 to the outside of the light source device 100 without providing the heat radiation member 150. In any case, the same effect as that described above can be obtained.
[First Modification of First Embodiment]
A first modification of the first embodiment will now be described. Here, a difference from the first embodiment will be explained, and like reference numerals denote like parts to omit a description thereof.
The heat transfer member 160 is interposed between a light conversion element 130 and a heat storage member 140. In the example shown in
In this modification, heat generated by the light conversion element 130 at the distal end portion of the light source device 101 is transferred to the heat storage member 140 at the proximal end portion of the light source device 101 through the heat transfer member 160. Like the first embodiment, part of the heat transferred to the heat storage member 140 is stored in the heat storage member 140, and part of the heat is transferred to the heat radiation member 150 and radiated from the heat radiation member 150.
According to this modification, the heat storage member 140 and the heat radiation member 150 can be arranged at positions apart from the light conversion element 130. For example, in the light source device used for illuminating a narrow space, reducing a size of an illumination light emitting portion may be demanded. In such a case, according to this modification, the heat storage member 140 or the heat radiation member 150 that is relatively large can be arranged at a position apart from the distal end portion at which the light conversion element 130 required to be miniaturized is arranged. As a result, an increase in temperature of the distal end portion of the light source device 101 can be further suppressed. Additionally, the light source device 101 according to this modification exercises an effect relative to use in a situation where radiating heat to the outside of the device is difficult at the distal end portion of the light source device 101.
As described above, for example, the heat transfer member 160 functions as a heat transfer unit that transfers heat generated in the light conversion unit to the heat radiation unit or the heat storage unit. It is to be noted that heat radiation from the heat transfer member 160 may be effectively used by increasing a length of the heat transfer member 160. That is, the heat transfer member 160 may be configured to function as the heat radiation member 150. Further, in this modification, the heat storage member 140 is arranged in contact with the heat radiation member 150 on the heat radiation member 150 side, but the heat storage member 140 may be arranged in contact with the light conversion element 130 on the light conversion element 130 side, and this heat storage member 140 and the heat radiation member 150 may be thermally connected through the heat transfer member 160.
A second embodiment will now be described. A difference from the first modification of the first embodiment will be explained, and like reference numerals denote like parts to omit a description thereof.
The light conversion element 130 and the first heat storage member 242 are thermally connected through a first heat transfer member 262 that has the same configuration and functions in the same manner as the heat transfer member 160. Likewise, the light conversion element 130 and the second heat storage member 244 are thermally connected through a second heat transfer member 264 that has the same configuration and functions in the same manner as the heat transfer member 160.
A distance between the light conversion element 130 and the first heat storage member 242 is different from a distance between the light conversion element 130 and the second heat storage member 244. That is, length of the first heat transfer member 262 and that of the second heat transfer member 264 are different from each other. In this embodiment, the first heat radiation member 252 is arranged to be closer to the light conversion element 130 than the second heat radiation member 254, and the first heat transfer member 262 is shorter than the second heat transfer member 264. Therefore, if the first heat transfer member 262 and the second heat transfer member 264 are formed into the same configuration by using the same material, the first heat transfer member 262 has higher thermal conductance. Thus, in this embodiment, the first heat transfer member 262 and the second heat transfer member 264 have materials and/or configurations different from each other, and the first heat transfer member 262 and the second heat transfer member 264 have the same thermal conductance. For example, when the second heat transfer member 264 has a thickness and/or a width larger than the first heat transfer member 262, the first heat transfer member 262 and the second heat transfer member 264 are adjusted to have the same thermal conductance. Furthermore, both the first heat transfer member and the second heat transfer member may be made of a graphite sheet as the same material or made of different materials. Even if different materials are used, the thermal conductance can be adjusted.
When the thermal conductance is adjusted as described above, quantities of heat that are transferred to the first heat radiation member 252 and the second heat radiation member 254 and radiated from the same become equal to each other. As a result, the first heat radiation member 252 and the second heat radiation member 254 have the same surface temperature.
In this embodiment, when the heat radiation members, i.e., the first heat radiation member 252 and the second heat radiation member 254 are provided, heat generated by the light conversion element 130 can be dispersed to such members. As a result, the light source device 200 can be prevented from locally having a high temperature.
In this embodiment, although the first heat radiation member 252 and the second heat radiation member 254 have the equivalent heat radiation capability, when there is a difference between their heat radiation capabilities, setting the thermal conductance of the first heat transfer member 262 and that of the second heat transfer member 264 to be proportionate to a ratio of inverse numbers of the thermal conductance of the first heat radiation member 252 and that of the second heat radiation member 254 enables equalizing temperatures of the first heat radiation member 252 and the second heat radiation member 254. Further, in this embodiment, the description refers to the example where the number of each of the heat transfer members, the heat storage members, and the heat radiation members is two, but this number may be three or more as a matter of course.
Furthermore, in this embodiment, the light conversion element 130 and the first heat storage member 242 are thermally connected through the first heat transfer member 262, and the light conversion element 130 and the second heat storage member 244 are thermally connected through the second heat transfer member 264, but one of the first heat storage member 242 and the second heat storage member 244 may be thermally directly connected to the light conversion element 130.
[First Modification of Second Embodiment]
A first modification of the second embodiment will now be described. Here, a difference from the second embodiment will be explained, and like reference numerals denote like parts to omit a description thereof.
A first heat storage member 242 and a second heat storage member 244 are thermally connected to the heat transfer member 266. A first heat radiation member 252 is thermally connected to the first heat storage member 242, and a second heat radiation member 254 is thermally connected to the second heat storage member 244. The first heat radiation member 252 and the first heat storage member 242 are arranged to be closer to a light conversion element 130 than the second heat radiation member 254 and the second heat storage member 244. Therefore, thermal resistance from the light conversion element 130 to the first heat storage member 242 is lower than thermal resistance from the light conversion element 130 to the second heat storage member 244.
Based on the above description, when configurations of the first heat storage member 242 and the first heat radiation member 252 are set to be equal to configurations of the second heat storage member 244 and the second heat radiation member 254, changes in temperature of these members are as shown in
According to this modification, in a state that heat radiation efficiencies of the first heat radiation member 252 and the second heat radiation member 254 and the thermal conductance of the heat transfer member 266 are increased as much as possible, the thermal capacities of the first heat storage member 242 and the second heat storage member 244 can be set in accordance with the heat radiation efficiencies of the first heat radiation member 252 and the second heat radiation member 254, and the surface temperatures of the first heat radiation member 252 and the second heat radiation member 254 are allowed to coincide with each other. Therefore, heat generated from the light conversion element 130 can be radiated to the outside of the device without locally increasing a temperature on the surface of the light source device 201.
A third embodiment will now be described. A difference from the first modification of the first embodiment will be explained, and like reference numerals denote like parts to omit a description thereof. A light source device 300 according to this embodiment is a light source device in which a portion between a distal end portion at which a light conversion element 130 is arranged and a proximal end portion at which a primary light source 110 is arranged is bent.
As shown in
When the light source device 300 is bent, an elongating or contracting force is applied to the heat transfer member 360. Here, since the heat transfer member 360 has a helical shape and is deformable, stress can be prevented from being locally concentrated on the heat transfer member 360. As a result, in the light source device 300 according to this embodiment, the heat transfer member 360 can be bent without being fractured.
It is to be noted that the shape of the heat transfer member 360 is not restricted to the helical shape. For example, it is possible to adopt any shape, e.g., a zigzag shape as long as it has a shape in which the heat transfer member can elongate and contract as a whole. In the description with reference to
[First Modification of Third Embodiment]
A first modification of the third embodiment will now be described. A difference from the third embodiment will be explained, and like reference numerals denote like parts to omit a description thereof.
In this embodiment, a heat radiation member 150 is arranged at a position on a proximal end side apart from a light conversion element 130 to surround a peripheral surface of the light source device 300. A heat transfer member 361 connected to the light conversion element 130 is inserted in the light source device 301 until it reaches a region where the heat radiation member 150 is arranged. A portion between the heat transfer member 361 and the heat radiation member 150 is filled with the gel-like heat storage member 340. The gel-like heat storage member 340 deforms when a force is applied thereto.
When the light source device 301 is bent, a force is applied to the heat transfer member 361 along a longitudinal direction thereof. When the force is applied to the heat transfer member 361 by bending in this manner, the gel-like heat storage member 340 deforms, and hence a position of the heat transfer member 361 shifts as shown in
It is to be noted that, when the heat storage member 340 may include a fluid such as water, air, and a slurry liquid having heat storage capsules dispersed therein, and others besides the gel-like heat storage material and the heat transfer member 361 is thermally connected to the heat radiation member 150 without mechanically fixing the heat transfer member 361, the same effect can be obtained.
[Second Modification of Third Embodiment]
A second embodiment of the third embodiment will now be described. Here, a difference from the first modification of the third embodiment will be explained, and like reference numerals denote like parts to omit a description thereof.
According to this modification, when the light source device 302 is bent and force is applied to the heat transfer member 361, the gel-like heat transfer member 362 deforms, and stress can be prevented from being locally concentrated on the heat transfer member 361. Therefore, according to this modification, the indestructible and bendable light source device 302 can be likewise configured. As described above, for example, the gel-like heat transfer member 362 functions as a deformation heat transfer member.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-243207 | Nov 2011 | JP | national |
This application is a Continuation application of PCT Application No. PCT/JP2012/077896, filed Oct. 29, 2012 and based upon and claiming the benefit of priority from prior Japanese Patent Application No. 2011-243207, filed Nov. 7, 2011, the entire contents of all of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2012/077896 | Oct 2012 | US |
| Child | 14269604 | US |
