Patent Application
20120069570
The present invention relates to an illumination device and to a method for assembly of an illumination device.
Light-emitting-diode (LED) lamps are known in the art. A LED lamp is a lamp that uses LEDs as the source of light. In such lamps, multiple diodes may be used for either increasing the output power of the lamp or for providing a white light as a single LED emits in a narrow band of wavelengths. LED lamps may be used for general lighting or even more specific lighting as the colour and the output power may be tuned.
Generally, a lamp or illumination device comprises a light source arranged to generate light and mounted on, or at least connected to, a circuit board. The light source is arranged within an encapsulating housing usually having the shape of a bulb. In addition to provide maximum light output and/or a specific colour of light, the design of an illumination device needs to take into account the evacuation of heat generated by the light source(s) and/or the electronics connected to the light source(s).
For example, American patent application US2010/0008086 discloses a white LED-based lighting device comprising a group of solid state light emitting diodes, electronics to activate the light emitting diodes and an encapsulating housing. For conducting or transferring outwardly heat generated from within the white light LED device, the encapsulating housing includes air vents and heat-sinking components.
Generally, a disadvantage of prior art systems may be that such systems require a high number of components including specific details for evacuation of heat (e.g. an encapsulating housing, light source(s), a circuit board, air-vents and heat sinking components), thereby rendering the assembly of the system rather complex.
Hence, it is an object of the present invention to alleviate the above mentioned drawback, and to provide an illumination device having a convenient design for facilitating its assembly.
This and other objects of the present invention are achieved by means of an illumination device and a method for assembly of an illumination device as defined by the independent claims. Other advantageous embodiments of the present invention are defined by the dependent claims.
According to a first aspect of the invention, an illumination device as defined in claim 1 is provided. The illumination device comprises a light source arranged to generate light, a carrier arranged to support the light source and an envelope enclosing the light source and the carrier. The light source is in thermal contact with the carrier and the envelope comprises at least two enveloping parts which, when joined together, form the envelope. The carrier is arranged in thermal contact with at least one of the enveloping parts for dissipating heat out of the illumination device.
According to a second aspect of the present invention, a method for assembly of an illumination device comprising a light source arranged to generate light as defined in claim 11 is provided. The method comprises the steps of mounting the light source in thermal contact with a carrier and enclosing the light source by joining at least two enveloping parts, thereby forming an envelope enclosing the light source. The carrier is arranged in thermal contact with at least one of the enveloping parts for dissipating heat out of the illumination device.
The present invention makes use of an understanding that the envelope or bulb of an illumination device may comprise at least two enveloping parts which, when joined together, form the envelope (or encapsulating housing of the illumination device). The present invention is advantageous in that it provides a convenient design which facilitates the assembly of an illumination device (such as a lamp or spot light). Using two enveloping parts, the light source and the carrier may conveniently be mounted together while the two enveloping parts are separated and then enclosed in the envelope by joining the two enveloping parts. It will be appreciated that more than two enveloping parts may be employed and that the present invention is not limited to an illumination device comprising an envelope made of only two enveloping parts.
The present invention makes also use of an understanding that the envelope (or bulb) of the illumination device may act as a heat sink and serve for dissipating heat (e.g. generated by the light source or any electronics connected to the light source) out of the illumination device. For this purpose, the light source is arranged in thermal contact with a carrier which itself is in thermal contact with at least one of the enveloping parts of the envelope. With the present invention, the whole surface of the illumination device, i.e. the envelope, acts as a heat sink. Thus, the present invention is advantageous in that an effective transfer of heat to the outside environment of the illumination device is provided.
According to an embodiment, the carrier and the envelope may be made of ceramic material, which is advantageous in that it is a kind of material having good thermal conductivity, thereby allowing a relative efficient transfer of heat. For example, the ceramic material may be poly crystalline aluminium oxide (PCA), which is advantageous in that it is a translucent ceramic material.
According to an embodiment, the envelope may have the shape of a bulb (or lamp bulb). In particular, the enveloping parts may be two bulb halves.
According to an embodiment, an enveloping part and at least part of the carrier (or a first part of the carrier or first carrier) may form a single integrated part, which is advantageous in that the number of components is reduced, thereby facilitating even further the assembly of the illumination device. The present embodiment is also advantageous in that the enveloping part and the part of the carrier (e.g. a bulb half and half of the carrier) may be manufactured as one single part from one single mould. The corresponding enveloping part(s) and part of the carrier for forming the envelope and the carrier may also be manufactured from one single mould, preferably the same mould.
According to another embodiment, the carrier may be arranged at a junction between two enveloping parts. In the present embodiment, the carrier and the enveloping parts are separate parts.
According to an embodiment, the enveloping parts may advantageously be configured to fit one to another, thereby facilitating the assembly of the illumination device.
According to an embodiment, the carrier may be arranged along an axis extending from the base of the illumination device to its top. Alternatively, the carrier may be arranged along a direction crossing an axis extending from the base of the illumination device to its top. In these embodiments, the carrier divides the space defined by the envelope in at least two compartments. A plurality of light sources may then advantageously be used and distributed on each side of the carrier such that an uniform illumination is provided.
According to an embodiment, the envelope may comprise a transmissive region arranged to transmit at least part of the light generated by the light source (especially when the light source emits in the visible range of the wavelength spectrum, i.e. 380-780 nm). The transmissive region may be translucent (transmitting and scattering of light) or be transparent (substantial unhindered transmission). Advantageously, the transmissive region is translucent, thereby preventing a user from perceiving the light source(s) and optional electronics within the envelope. As mentioned above, the envelope may be made of PCA, thereby providing a translucent envelope. Thus, the envelope or encapsulating housing of the illumination device is advantageous in that it integrates a number of functionalities such as an optical function, a thermal function and a mechanical function.
According to an embodiment, the carrier may comprise a reflective region arranged to reflect at least part of the light generated by the light source(s). Alternatively or in addition, the carrier may comprise a transmissive region arranged to transmit at least part of the light generated by the light source.
According to an embodiment, the light source may be at least one light emitting diode (LED) or at least one LED package. The light source may for instance comprise an RGB LED (red green blue light emitting diode), or a plurality of diodes arranged to provide white light, such as an RGB combination, or a combination of blue and yellow, or a combination of blue, yellow and red, etc. Optionally, the illumination device may be arranged to provide coloured light.
The light source may also comprise a plurality of light sources (such as a plurality of LEDs), that is (are) able to provide light at different predetermined wavelengths, depending upon the driving conditions. Hence, in a specific embodiment, the illumination device may further comprise a controller (attached to or external from the illumination device), arranged to control the colour of the illumination device light in response to a sensor signal or a user input device signal.
In the following, the invention may be further described with reference to a LED as preferred embodiment of the light source. Hence, in the following the term “LED” may also refer to a light source (or a plurality of light sources) in general, unless indicated otherwise or clear from the context, but preferably refers to a LED. Further, the term “LED” especially refers to solid state lighting (solid state LEDs).
According to an embodiment, the light source may emit light in the visible range, but may also, in another embodiment, alternatively or additionally emit in the UV range. As mentioned above, the light source may comprise a LED. In a further embodiment, the light source is a LED arranged to generate blue light. The blue light emitting source may be used per se, or may be used in combination with luminescent material, e.g. arranged at the envelope or at least one of the enveloping parts, such as to provide white light, or may be used in combination with one or more other LEDs generating light at other wavelengths. Combinations of such embodiments may also be applied.
According to an embodiment, the carrier or part of the carrier may be glued to an enveloping part of the envelope. Advantageously, the glue has good thermal properties such that heat can be dissipated from the carrier to the enveloping part.
Alternatively, the carrier may be inserted at a junction between two enveloping parts. In the present example, the carrier is advantageously pressed between two enveloping parts such that a good thermal contact is provided between the carrier and the enveloping parts for heat dissipation.
According to an embodiment, a base of the envelope (or illumination device) is inserted in a socket acting as an holder. The socket may also be configured to provide electricity to the light source.
In the present application, the term “at least” may in embodiments also indicate “all” or “completely”.
It is noted that the invention relates to all possible combinations of features recited in the claims.
This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing various exemplifying embodiments of the invention.
a-4c illustrate, in a schematic manner, a process flow of the method for assembly of an illumination device according to an exemplifying embodiment of the present invention.
With reference to
The illumination device 100 further comprises two carrier parts 121 and 122 (or a first carrier 121 and a second carrier 122) arranged to support the light source 110 or LED packages 111-114. In the following, the two carrier parts 121 and 122 may also be referred to as a single carrier, when the two parts are intended to be joined together, and will generally be referred to as a carrier 120.
The illumination device 100 comprises also two enveloping parts 131 and 132 which, when joined together, form an envelope or encapsulating housing generally denoted as a single envelope 130 in the following. The envelope 130 encloses the light sources 111-114 and the carriers 121 and 122. The light sources 111-114 (or light source 110) are arranged in thermal contact with the carriers 121 and 122. The carrier 120 is arranged in thermal contact with the enveloping parts 131 and 132, respectively.
Using such a design, when the illumination device is powered on, heat may be generated by the light source(s) 111-114 and be dissipated out of the illumination device 100 via the carriers 121 and 122 and the enveloping parts 131 and 132.
In the present embodiment, the first and second carriers 121 and 122 divide the illumination device 100 in two compartments. Advantageously, the light source(s) 111-114 of the illumination device may be distributed on each side of the first and second carriers 121 and 122 for improving the uniformity of the light emitted from the illumination device 100.
The envelope 130 may especially be arranged to receive all light from the light source(s) 111-114. Further, the envelope 130 may especially be arranged to allow escape of light of the light source(s) 111-114.
When a plurality of light sources are used and the light sources emit light at different wavelengths, the envelope 130 may thus also be indicated as a mixing chamber. Mixing may also be of relevance when a luminescent material is used that is arranged remote from a light source (from which it absorbs part of the light to provide luminescent material light), e.g. arranged at the envelope or part of the envelope.
Advantageously, the envelope 130 may comprise a transmissive region arranged to transmit at least part of the light generated by the light sources 111-114.
According to an embodiment, the carrier 120 may also comprise a transmissive region, which is advantageous in that light coming from a compartment of the envelope in direction to the carrier may be transmitted through the carrier and, then, transmitted out of the illumination device via the envelope 130. In particular, the envelope 130 may be made of a material having light transmissive properties such that an efficient transmission of light through the envelope is achieved.
Alternatively, or in addition, the carrier 120 may comprise a reflective region arranged to reflect at least part of the light generated by the light source(s), which is advantageous in that light emitted in a compartment of the envelope and directed towards the carrier may be reflected against the carrier and transmitted out of the illumination device via the same compartment of the envelope. It will be appreciated that the carrier may be designed with a number of various regions being either transmissive or reflective such that, e.g., a desired light distribution is achieved.
In the embodiment shown in
According to an embodiment, both the envelope and the carrier comprises ceramic material, which is advantageous in that it improves the transfer of heat from the illumination device.
The term “ceramic” is known in the art and may especially refer to an inorganic, non-metallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous, i.e., a glass. Most common ceramics are crystalline. The term ceramic especially relates to materials that have sintered together and form pieces (in contrast to powders). The ceramics used herein are preferably polycrystalline ceramics.
The ceramic material may for instance be based on one or more materials selected from the group consisting of Al2O3, AlN, SiO2, Y3Al5O12 (YAG), an Y3Al5O12 analogue, Y2O3 and TiO2, and ZrO2. The term an Y3Al5O12 analogue refers to garnet systems having substantially the same lattice structure as YAG, but wherein Y and/or Al and/or O, especially Y and/or Al are at least partly replaced by another ion, such as one or more of Sc, La, Lu and G, respectively.
According to an embodiment, the ceramic material may be Al2O3, which is a translucent material. Al2O3 can also be made highly reflective when it is sintered at a temperature in the range of about 1300-1700° C., such as in the range of about 1300-1500° C., like 1300-1450° C. This material is also known in the art as “brown” PCA (polycrystalline alumina).
The term “based on” indicates that the starting materials to make the ceramic material substantially consist of one or more of the herein indicated materials, such as for instance Al2O3 or Y3Al5O12 (YAG). This does however not exclude the presence of small amounts of (remaining) binder material, or dopants, such as Ti for Al2O3, or in an embodiment Ce for YAG.
The ceramic material may have a relatively good thermal conductivity. Preferably, the thermal conductivity is at least about 5 W/mK, such as at least about 15 W/mK, even more preferably at least about 100 W/mK. YAG has a thermal conductivity in the range of about 6 W/mK, poly crystalline alumina (PCA) in the range of about 20 W/mK, and AN (aluminum nitride) in the range of about 150 W/mK or larger.
Referring again to
According to an embodiment, referring to e.g.
Referring to
With reference to any embodiments described above with reference to
With reference to
As illustrated in
In the present embodiment, as for the embodiments described with reference to
Alternatively, the carrier may be arranged along a direction crossing the axis 170 extending from the base of the illumination device to its top.
In either case, the carriers define compartments within the envelope of the illumination device.
With reference to
a-4c schematically illustrate the assembly of an illumination device comprising a first bulb half 131 with a first carrier 121 on which a first light source 111 is mounted and a second bulb half 132 with a second carrier 122 on which a second light source 112 is mounted.
a shows the first enveloping part or bulb half 131 comprising the first carrier 121. The first bulb half 131 and the first carrier 121 may be a single integrated part, e.g. made out of a single mould. Alternatively, the first carrier 121 and the first bulb half are two separate parts and the first carrier 121 may be glued to the inside of the first bulb half 131. Advantageously, the glue has good thermal conductive properties such that heat can effectively be transferred from the first carrier 121 to the first bulb half 131.
In a first step 4100, a light source 111 is mounted in thermal contact with the first carrier 131. The light source 111 may for instance be attached to the carrier by means of a clip.
A similar step may then be applied with the second carrier 132 to which a second light source 112 is mounted in thermal contact.
In a second step 4200, the first light source 111, the first carrier 121, the second light source 112 and the second carrier 122 are enclosed by joining the two enveloping parts 131 and 132, such as illustrated in
As a result, an envelope 130 such as shown in
In this respect, the light source may advantageously be high-voltage (HV) LEDs, which is advantageous in that the number of components necessary to form the illumination device is further reduced as HV LEDs do not require any driver.
Even more advantageously, phase-shifted HV LEDs may be used and distributed on the carrier 130 (or the carriers 131 and 132) for preventing any stroboscopic effect.
The present invention may be useful for any kind of lamps such as a spot light or a standard lamp. The present invention may be applied for illumination devices used in homes, hospitality, outdoor, offices, industry and retail.
Even though the invention has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art. The described embodiments are therefore not intended to limit the scope of the invention, as defined by the appended claims.
For example, although the embodiments described above relate to an illumination device having a standard bulb shape, any other suitable shape may be envisaged. Further, although the embodiments described above comprise a first and a second carrier, it will be appreciated that the illumination device may comprise only one carrier in thermal contact with at least one of the enveloping parts. Further, the illumination device may also comprise more than two carriers or carrier parts.
Further, although the present invention has been described with reference to two enveloping parts for forming the envelope or encapsulating housing (or bulb), the present invention is not limited to such an embodiment and more than two enveloping parts may be used to form the envelope of the illumination device.
It will also be appreciated that the number of LEDs or light sources and their respective wavelengths will be selected in accordance with the desired application.
| Number | Date | Country | Kind |
|---|---|---|---|
| 09161346.3 | May 2009 | EP | regional |
| 09166081.1 | Jul 2009 | EP | regional |
| 10162146.4 | May 2010 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB10/52282 | 5/21/2010 | WO | 00 | 11/22/2011 |
