JP2007066696A - Lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system in which achieving higher brightness is realized by improving reliability of a Peltier module. <P>SOLUTION: In this system, a plurality of Peltier modules 110, 120 are used, and this is provided with a light-emitting members 101, a first heat conductive members 102 thermally joined with the light-emitting member, and a plurality of heat conductive electrically insulated members 111, 121 which are respectively installed between the cooling faces of the plurality of Peltier modules and the first heat conductive members, and which have heat conductivity and electrical insulation characteristics. By this, stress generated in the inside of the Peltier modules can be reduced to half or less than that in conventional one. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lighting device.

  Conventionally, light emitted from a light source device such as a light emitting diode or a semiconductor laser is incident on a light valve such as a reflective display element, and image light emitted from the light valve is enlarged and projected onto a screen by a projection lens or the like. The device is widely known. In a display device, securing the brightness of a display image is an important issue. For example, it has been studied to increase the brightness by increasing a supply current to a light-emitting diode that is a light source device. However, since the amount of heat generation increases as the amount of emitted light increases, an illumination device including an electronic cooling element as a cooling device has been proposed (for example, Patent Document 1).

  The illumination device in Patent Document 1 can be cooled by a light source including a light emitting diode chip and a Peltier element which is a thermoelectric conversion device, a so-called electronic cooling element. Specifically, the light emitting diode is directly mounted on the cooling surface of the Peltier element. In Patent Document 1, the light source device and the Peltier element are electrically connected in series so that the supply current of the light emitting diode and the supply current of the Peltier element are the same. Furthermore, a light source array in which a plurality of light emitting diode chips are mounted on a single Peltier element can be configured.

  Hereinafter, a conventional lighting device in Patent Document 1 will be described with reference to FIG. FIG. 6 is a side view of a conventional lighting device.

  An upper substrate 5 is adhered and disposed on the upper surface of each upper electrode 6 of each Peltier element. The upper surface of the upper substrate 5 constitutes the cooling surface 2 of the Peltier module 1. A lower substrate 7 is disposed on the lower surface of each lower electrode 8 of each Peltier element. A plurality of light emitting diode chips 3 (hereinafter referred to as LED chips) are mounted on the upper surface of the upper substrate 5 to form a light source array 4. The light source array 4 and the Peltier module 1 are electrically connected in series.

  The upper substrate 5 and the lower substrate 7 are made of a ceramic material having electrical insulation and high thermal conductivity. By adopting a material having electrical insulation properties, short circuit between each Peltier module 1 and between Peltier module 1 and LED chip 3 is prevented.

  Next, the operation of the conventional illumination device in Patent Document 1 will be described.

  When a current is supplied from the DC power source 9 to the light source array 4, each LED chip 3 constituting the light source array 4 emits light. This LED chip 3 has the property that it generates heat as it emits light and its luminous efficiency decreases as the temperature rises. However, since the light source array 4 and the Peltier module 1 are connected in series, a current is supplied from the DC power source 9 to the Peltier module 1 together with the light source array 4, and the Peltier module 1 is driven. And since each LED chip 3 which comprises the light source array 4 is mounted in the cooling surface 2 of the Peltier module 1, each LED chip 3 is cooled by the driven Peltier module 1. FIG. Thereby, the temperature rise of each LED chip 3 is suppressed and the fall of luminous efficiency is prevented.

Next, consider a case where the amount of light emitted from each LED chip 3 is increased by increasing the supply current from the DC power supply 9 to the light source array 4. In this case, the amount of heat generated increases as the amount of light emitted from the LED chip 3 increases, and the temperature of the LED chip 3 may rise. However, since the light source array 4 and the Peltier module 1 are connected in series, the supply current of the Peltier module 1 increases as the supply current to the light source array 4 increases. Thereby, the cooling capacity of the Peltier module 1 is improved and the cooling of the LED chip 3 is enhanced. Therefore, the temperature rise of each LED chip 3 constituting the light source array 4 is suppressed, and a decrease in light emission efficiency is prevented.
JP 2004-342557 A

  However, the configuration of such a conventional lighting device has the following problems. In the case of forming a light source array, a plurality of LED chips 3 are mounted on the upper substrate 5 of one Peltier module 1, so that one Peltier module 1 and the upper substrate 5 that are substantially equal to the size of the light source array are used. It is done. In the Peltier module 1, the upper substrate 5 is cooled and the lower substrate 7 is heated. At this time, the lower substrate 7 tends to expand larger than the upper substrate 5 (or the upper substrate 5 tends to contract). Then, stress is generated at the respective joints of the upper electrode 6, the n-type semiconductor, the p-type semiconductor, and the lower electrode 8 that are joined between the upper substrate 5 and the lower substrate 7. When this stress reaches the stress at which the joint between the upper electrode 6 or the lower electrode 8 and the n-type semiconductor or the p-type semiconductor peels, peeling occurs.

  The expansion rate is constant regardless of the size of the member when compared at the same temperature rise. However, the expansion amount increases as the size of the member increases when compared with the same temperature rise. Therefore, since the stress increases as the size of the upper electrode 6 and the lower electrode 8 of the Peltier module 1 increases, the life of the Peltier module 1 is increased when the size of the light source array is increased in the configuration of the conventional lighting device. There was a problem of a decrease.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide an illuminating device that achieves high brightness by improving the reliability of the Peltier module.

  The object is to provide a light emitting member, a first heat conducting member thermally bonded to the light emitting member, a plurality of Peltier modules, a cooling surface of the plurality of Peltier modules, and the first heat conducting member. And a plurality of thermally conductive and electrically insulating members each having thermal conductivity and electrical insulation.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the illuminating device by which high brightness is implement | achieved by the reliability improvement of a Peltier module.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a cross-sectional view of the lighting apparatus according to Embodiment 1. FIG. The lighting device 100 in the present embodiment uses two Peltier modules. Hereinafter, the first Peltier module 110 and the second Peltier module 120 are referred to. A first thermally conductive and electrically insulating member 111 is joined to the first upper electrode 112 that is the cooling surface of the first Peltier module 110. In addition, a second thermally conductive electrical insulating member 121 is joined to the second upper electrode 122 that is the cooling surface of the second Peltier module 120. The first thermally conductive electrical insulating member 111 and the second thermally conductive electrical insulating member 121 are thermally joined to the first thermally conductive member 102. The light emitting member 101 is thermally bonded to the first thermal conductive member 102.

  As the light emitting member 101, an LED chip or a semiconductor laser is used. LED chips and semiconductor lasers are heating elements that generate heat as they emit light. Also, LED chips and semiconductor lasers have a large temperature dependence on optical performance. Therefore, cooling is required to stably obtain a desired light amount. The light emitting member 101 is thermally bonded to the first heat conductive member 102. The thermal bonding means a state in which a heat transfer path of heat is formed between two members, and a state in which they are connected via other members such as contact, adhesion, and adhesive. Including. The same applies hereinafter.

  The first heat conductive member 102 is a heat diffusion member for efficiently transferring heat generated by the light emitting member 101 from the light emitting member 101 to the first Peltier module 110 and the second Peltier module 120. The first heat conductive member 102 is preferably a metal material having high heat conductivity. For example, if a copper alloy or aluminum is used, good heat conduction can be achieved.

  FIG. 2 is an explanatory diagram of the cooling effect of the Peltier element. The basic structure of the Peltier device 20 is that a p-type semiconductor 21p with insufficient electrons and an n-type semiconductor 21n with excess electrons are electrically connected in series and thermally in parallel. When the power source 22 is connected to the Peltier element 20 as shown in FIG. 2, the current flows from the lower electrode 23n of the n-type semiconductor 21n to the n-type semiconductor 21n, the upper electrode 24, and the p-type semiconductor 21p in this order, and the lower part of the p-type semiconductor 21p. It flows to the electrode 23p. Energy moves in the opposite direction with the electrons. In the n-type semiconductor 21n, energy for moving electrons from the upper electrode 24 to the n-type semiconductor 21n and energy for moving inside the n-type semiconductor 21n to the lower electrode 23n are obtained from the upper electrode 24 side. As a result, energy is insufficient on the upper electrode 24 side, and the temperature is lowered. In contrast, on the lower electrode 23n side, the energy taken by the electrons is released and warmed. Further, in the p-type semiconductor 21p, holes function similarly. A metal such as copper is used for the upper electrode 24 and the lower electrodes 23p and 23n.

  FIG. 3 shows a perspective view of the Peltier module. The above-described Peltier elements are electrically connected in series so that p-type and n-type semiconductor elements are alternated to form a Peltier module. The positive electrode side of the n-type semiconductor and the negative electrode side of the p-type semiconductor are all arranged on the same side. That is, the upper electrodes of the above-described Peltier elements are all arranged on the same side. In addition, although the thing which joined the ceramic substrate which is a heat conductive insulating member to the electrode of both surfaces of the above-mentioned Peltier module may be called a Peltier module, in the present invention, the above-mentioned Peltier module where the ceramic substrate is not joined Is called a Peltier module.

  A first thermally conductive and electrically insulating member 111 is joined to the first upper electrode 112 that is the cooling surface of the first Peltier module 110. A heat conductive electrical insulation member is a member which has heat conductivity and has electrical insulation. As the thermally conductive electrical insulating member, a ceramic material having electrical insulation and high thermal conductivity is used. Similarly, a second heat conductive electrically insulating member 121 is joined to the second upper electrode 122 which is a cooling side electrode of the second Peltier module 120.

  A third thermally conductive electrically insulating member 114 is joined to the first lower electrode 113 which is the heat dissipation surface of the first Peltier module 110. In addition, a fourth thermally conductive electrical insulating member 124 is joined to the second lower electrode 123 which is the heat dissipation surface of the second Peltier module 120.

  As the second, third, and fourth thermally conductive electrical insulating members 121, 114, and 124, the same material as the first thermally conductive electrical insulating member 111 can be used.

  The first thermally conductive electrical insulating member 111 and the second thermally conductive electrical insulating member 121 are thermally joined to the first thermally conductive member 102. It is also preferable to apply a thermally conductive grease or the like as an auxiliary thermal bonding member to the boundary portion of the bonding portion in order to stabilize the thermal bonding.

  The third thermally conductive electrical insulating member 114 and the fourth thermally conductive electrical insulating member 124 are thermally joined to the second thermally conductive member 103 having elasticity or plasticity. The second heat conductive member 103 may be a non-ferrous metal or a metal. The second thermal conductive member 103 is preferably one that is easily elastically deformed or plastically deformed and has high thermal conductivity.

  The illumination device 100 according to the present embodiment further includes a heat radiating unit 130 that radiates heat from the first Peltier module 110 and the second Peltier module 120. In the present embodiment, a combination of a heat sink 131 and a fan 132 is used as the heat radiating means 130.

  As the heat sink 131, a metal such as aluminum or copper is used. The heat sink 131 and the second thermally conductive member 103 are thermally bonded. And it is comprised so that a wind can be sent to the several projection part of the heat sink 131 by the fan 132. FIG.

  As the heat radiating means 130, the heat sink 131 or the fan 132 may be used alone. Also, a so-called water cooling device that forcibly circulates antifreeze or the like and moves the heat generation amount to dissipate heat using a radiator or the like in order to cope with a large change in the heat generation amount may be used.

  Next, operation | movement of the illuminating device 100 of this Embodiment is demonstrated.

  The light emitting member 101 emits light when power is supplied from a power supply device (not shown) in order to obtain a desired light output. Electric power that is not converted into light by the light emitting member 101 is converted into heat, and the light emitting member 101 generates heat. The heat generated in the light emitting member 101 is transmitted to the first heat conductive member 102. And heat is divided | segmented and transmitted to the 1st Peltier module 110 and the 2nd Peltier module 120 through the 1st heat conductive electrical insulation member 111 and the 2nd heat conductive electrical insulation member 121, respectively.

  The first Peltier module 110 and the second Peltier module 120 each have a power source independent of the LED chip, and power is supplied from each power source. An endothermic action occurs in the first upper electrode 112 and the second upper electrode 122. The heat divided and transferred to the first Peltier module 110 and the second Peltier module 120 is absorbed by the first upper electrode 112 and the second upper electrode 122, respectively.

  As described above, the light emitting member 101 is cooled to an optimum temperature state.

  The heat absorbed by the first upper electrode 112 and the second upper electrode 122 is transmitted from the first lower electrode 113 and the second lower electrode 123 to the second thermally conductive member 103. Then, the heat is transmitted to the heat sink 131 and is radiated from the plurality of protrusions of the heat sink 131 to the outside air. The fan 132 sends wind to the plurality of protrusions of the heat sink 131 to increase the heat dissipation efficiency from the heat sink 131.

  At this time, in the first Peltier module 110, a temperature difference is generated between the first thermally conductive electrical insulating member 111 and the third thermally conductive electrical insulating member 114. At this time, the third thermally conductive electrical insulating member 114 tends to expand larger than the first thermally conductive electrical insulating member 111 (or the first thermally conductive electrical insulating member 111 tends to contract). . A first upper electrode 112 joined between the first thermal conductive electrical insulation member 111 and the third thermal conductive electrical insulation member 114; an n-type semiconductor; a p-type semiconductor; Stress is generated at each joint portion of one lower electrode 113. When this stress reaches the stress at which the junction between the first upper electrode 112 or the first lower electrode 113 and the n-type semiconductor or the p-type semiconductor peels, peeling occurs. When peeling occurs, the current path of the first Peltier module 110 is interrupted, so that the first Peltier module 110 does not operate. The same applies to the second Peltier module 120.

  However, in the present embodiment, by using two Peltier modules, the heat conductive electrical insulating member can be reduced to half or less compared to a conventional lighting device using only one Peltier module. Therefore, since the expansion of the heat conductive electrical insulating member can be suppressed to less than half that of the prior art, it is possible to suppress the occurrence of the above-described peeling.

  In the present embodiment, the first thermal conductive member 102 also undergoes thermal deformation. As a result, the relative position between the first Peltier module 110 and the second Peltier module 120 changes. This change in position can be absorbed by elastic deformation or plastic deformation of the second thermal conductive member 103. Thus, the occurrence of stress on the first Peltier module 110 and the second Peltier module 120 can be suppressed.

  In the present embodiment, since the two Peltier modules can be driven independently, it is possible to set optimum cooling conditions by changing the respective driving conditions.

(Embodiment 2)
FIG. 4 is a cross-sectional view of the illumination device according to the second embodiment. Only differences between lighting device 200 in the present embodiment and lighting device 100 in the first embodiment will be described.

  The lighting device 200 in the present embodiment is obtained by omitting the third thermally conductive electrical insulating member 114 and the fourth thermally conductive electrical insulating member 124 from the lighting device 100 in the first embodiment. The first lower electrode 113 and the second lower electrode 123 are thermally bonded to the second thermal conductive member 203, respectively. Further, the second heat conductive member 203 has elasticity or plasticity and is electrically insulating.

  According to the present embodiment, in addition to the effects described in the first embodiment, an effect that the number of parts can be reduced can be obtained.

(Embodiment 3)
FIG. 5 is a cross-sectional view of the lighting apparatus according to Embodiment 3. Only differences between lighting device 300 in the present embodiment and lighting device 100 in the first embodiment will be described. Compared to the illumination device 100 in the first embodiment, in the present embodiment, a temperature detection means 301 for detecting the temperature of the light emitting member 101 is added, and the first Peltier module 110 and the second Peltier module are based on the detection information. Control means 302 is further provided for controlling the driving of 120 and controlling the respective cooling conditions.

  Although the temperature rise of the heat generating member 101 due to the supply of electric power can be estimated, it is important to know the actual temperature because the situation varies depending on variations in the actual lighting device 300 and other surrounding conditions. For this reason, in this embodiment, a temperature detection unit 301 such as a temperature sensor is installed around the light emitting member 101 or in a portion that is in contact with the light emitting member 101 and is correlated with the temperature of the light emitting member 101. Yes. In particular, a control unit 302 is provided that controls the driving conditions of the first Peltier module 110 and the second Peltier module 120, the driving conditions of the heat dissipation unit 130, and the like based on information from the temperature detection unit 301, respectively. .

  Note that the lighting device 200 according to Embodiment 2 may further include the above-described temperature detection unit 301 and control unit 302.

  Moreover, in each embodiment, although the case where two Peltier modules were used was demonstrated, two or more may be sufficient.

  It should be noted that the technical scope of the present invention is not limited to the above-described embodiments, and includes those in which various modifications are made to the above-described embodiments without departing from the spirit of the present invention. That is, the specific materials and configurations described in the embodiments are merely examples, and can be changed as appropriate.

  The illumination device according to the present invention is useful as a backlight such as a liquid crystal display, a light source of a projection display device, and the like.

Sectional drawing of the illuminating device which concerns on Embodiment 1. FIG. Illustration of the cooling effect of the Peltier element Perspective view of Peltier module Sectional drawing of the illuminating device which concerns on Embodiment 2. FIG. Sectional drawing of the illuminating device which concerns on Embodiment 3. FIG. Side view of a conventional lighting device

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Light emitting member 102 1st heat conductive member 103,203 2nd heat conductive member 110 1st Peltier module 111 1st heat conductive electrically insulating member 112 1st upper electrode 113 1st lower electrode 114 Third thermal conductive electrical insulation member 120 Second Peltier module 121 Second thermal conductive electrical insulation member 122 Second upper electrode 123 Second lower electrode 124 Fourth thermal conductive electrical insulation member 130 Heat dissipation means 131 Heat Sink 132 Fan 301 Temperature Detection Unit 302 Control Unit

Claims (8)

A light emitting member;
A first heat conducting member thermally bonded to the light emitting member;
Multiple Peltier modules,
A plurality of thermally conductive and electrically insulating members provided between the cooling surfaces of the plurality of Peltier modules and the first thermally conductive member, and having thermal conductivity and electrical insulation;
A lighting device comprising: A second heat conducting member having elasticity or plasticity;
A plurality of thermally conductive and electrically insulating members provided between the heat dissipation surfaces of the plurality of Peltier modules and the second thermally conductive member, and having thermal conductivity and electrical insulation;
The illumination device according to claim 1, further comprising:   The lighting device according to claim 1, further comprising a second heat conductive member thermally bonded to a heat radiation surface of the plurality of Peltier modules and having elasticity, plasticity, and electrical insulation.   The lighting device according to claim 1, further comprising a heat dissipating unit that dissipates heat from the plurality of Peltier modules.   The lighting device according to claim 2, further comprising a heat sink thermally bonded to the second heat conducting member.   The lighting device according to claim 1, wherein each of the plurality of Peltier modules is driven independently.   The lighting device according to claim 1, further comprising control means for independently driving the plurality of Peltier modules. Temperature detecting means for detecting the temperature of the light emitting member;
The lighting device according to claim 1, further comprising a control unit that independently drives the plurality of Peltier modules based on a detection result of the temperature detection unit.

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