DE102009042434A1 - Lighting device, lamp with the lighting device and method for producing a lighting device - Google Patents

Abstract

The lighting device (3) has at least one substrate (4) which is equipped on one side with at least one light source (6), the substrate (4) having a transparent base material. The lamp (1) has at least one lighting device (3), the lighting device (3) being introduced into a bulb (2), in particular a cylindrical glass bulb. In a method for producing the lighting device (3), the base material is fired together with the conductor structure (7). In another method for producing the lighting device (3), the conductor structure (7) is burned into the fired base material.

Description

The invention relates to a lighting device having at least one substrate which is equipped on one side with at least one light source. The invention further relates to a lamp with at least one such lighting device. The invention also relates to methods for producing such a lighting device.

In an LED lamp, one or more light emitting diodes (LEDs) equipped with substrates are often used. For a realization of a spatial light distribution of more than 180 ° in such an LED lamp, z. B. a LED retrofit lamp, so far, several rigid substrates can be used, which are equipped with LEDs on one side and wherein the substrates are arranged rotated to each other, z. B. twisted by 180 °. It is disadvantageous that the use of the several stocked substrates is expensive and requires a lot of space. Alternatively, a substrate can be used which is equipped with LEDs on both sides. While such a required space can be kept small, the two-sided assembly is relatively expensive. Yet another alternative is to use one-sided equipped rigid substrates with downstream optical fibers, which is complicated and expensive. Another alternative is to use band-shaped flexible substrates that are bent so that the LEDs applied to them radiate into different spatial sectors. The use of the flexible substrates has the disadvantage that here too a comparatively large space is required and also the substrate can not be equipped or only with comparatively small electronic components.

DE 202 14 661 U1 describes a festoon lamp having a transparent hollow body with metal end caps as contacts, wherein in the transparent hollow body at least one carrier is arranged, are arranged on the light-emitting semiconductor diodes, wherein the semiconductor diodes are connected to further electronic components, and wherein the elongated thin wires of the carrier are electrically connected to the metal end caps. The support may be a transparent glass support which, due to its transparency, is proposed for emission into the overall space.

It is the object of the present invention to provide a lighting device which avoids the above-mentioned disadvantages and in particular allows a radial light emission in an angular range of more than 180 ° in a comparatively simple and compact manner.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims.

The object is achieved by a lighting device, comprising at least one substrate which is equipped on one side with at least one light source. The substrate has a translucent base material with a thermal conductivity of at least 10 W / (m · K). Through the use of the translucent base material can be in a compact manner directly from the at least one light source radiated or deflected, z. B. simply reflected, light are directed through the substrate into the half-space, which is opposite to the main emission of the light sources ('rear half space'). As a result, a radiation angle of the lighting device of more than 180 ° can be achieved, wherein a proportion of light on the back can be generated in a simple manner without additional light sources. Due to the thermal conductivity of at least 10 W / (m · K), the substrate can also serve as an effective heat sink, for. B. in contrast to glass, which has a thermal conductivity in a range of only about 1 W / (m · K). Due to the high thermal conductivity, the substrate can also act as a heat sink, and it can be an additional heat sink smaller and cheaper, or it can even be dispensed with an additional heat sink at least on the substrate.

In particular, the substrate may be a rigid substrate.

The at least one light source may in particular comprise at least one semiconductor light source, for. B at least one light emitting diode or at least one laser diode. As a light-emitting diode (s) can or can be light-emitting diodes, z. B. single LEDs, and / or so-called. 'Bare die' LEDs, which z. B. have one or more flat, on a surface a submounts mounted LED chips used.

It is an embodiment that the base material has a light transmittance of at least 95%. This makes it possible to achieve a high light intensity in the rear, half-space. The base material may in particular have a light transmittance of at least 99%.

It is advantageous for the homogenization of the irradiated light when the substrate is diffusely translucent.

It is a further embodiment that the light source has a radiation angle of more than 180 °, that is also partially radiating backwards. This allows light from the light source directly through the Substrate are emitted in the rear half space.

It is a possible embodiment for achieving a partially backward radiating light source that the light source has at least one lens and the at least one lens of the light source has different fill levels of a luminous means or phosphor. Additionally or alternatively, the lens may be provided with an at least partially reflecting mirror layer which is designed such that it reflects a part of the light emitted by an emitter surface of the light-emitting diode into the rear half-space.

It is a further embodiment that the base material has a thermal conductivity λ of at least 30 W / (m · K). This allows the substrate as a particularly effective heat sink z. B. are used for heat spreading and / or heat dissipation.

The lighting device may additionally have one or more dedicated heat sinks.

It is still an embodiment that the substrate has a thickness of at least 0.5 mm to 2 mm. This also supports use as a heat sink.

It is also an embodiment that the base material is a transparent ceramic material, in particular oxide ceramic. Transparent ceramic material has a high thermal conductivity of typically 20 W / (m · K) or more, is mechanically strong and thermally resistant.

It is an embodiment that the base material is a PCA ("Polycrystalline Alumina") material. The PCA material in its green body form typically consists of an alumina powder with other metal oxides, such as. As lanthanum, gadolinium and / or yttrium oxide, which are converted by a sintering process at about 850 ° C in a solid. The PCA material is characterized by the fact that it is both diffusely translucent with a light transmittance of at least 99%, has good thermal conductivity with a thermal conductivity of at least 30 W / (m · K) and is highly heat-resistant as a sinterable material. PCA is also highly resistant to breakage.

Alternatively, translucent ceramics with or made of ZrO ₂ or even glass ceramics can be used.

It is also an embodiment that the lighting device has a plurality of substrates equipped with the at least one light source. As a result, a light intensity can be increased in a simple manner.

It is yet another embodiment that the substrate comprises a sintered base material and at least one conductor structure baked thereon. This has the advantage that the conductor structure (conductors, contact fields, etc.) is very resistant to abrasion and long-lasting and at the same time the base material can withstand the firing temperatures.

In general, the substrate or the lighting device can be linearly elongated, bent or configured in any other desired shape and contour.

The object is also achieved by a lamp, wherein the lamp has at least one lighting device as described above, wherein the lighting device is incorporated in a translucent piston.

The piston may be a plastic piston or a glass bulb. In a further development, the piston can be an elongated, in particular cylindrical piston. As a result, in particular a line lamp or a fluorescent tube can be replaced.

In a particular embodiment, the cylindrical piston may be a cylindrical glass bulb. The use of glass has the advantage of a high mechanical wear resistance (eg against scratches), temperature resistance and material resistance (eg to light-induced discoloration).

The lamp can for example be made so that the lighting device or the assembled substrate is inserted into the at least one side open piston and the at least one opening is then closed.

It is a further development that the lighting device or the assembled substrate is inserted into a glass bulb open at least on one side and the at least one terminal opening is then closed by fusing. In this case, a use of a temperature-resistant, substrate material of the lighting device, such as the PCA material, advantageous.

It is an embodiment that the piston is at least partially mirrored in a radiation direction of the at least one light source. This makes it possible to amplify a light intensity in the rear half space in a particularly simple manner.

It is a particular embodiment that the mirror coating is a partially permeable Mirroring is to obtain a uniform as possible Lichtabstrahlcharakteristik, in particular radial Lichtabstrahlcharakteristik, and not darken the front half space excessively.

It is still another embodiment that the base material, if it can be fired (eg, the PCA material), is fired together with the conductor pattern ('co-fired'). As a result, the lighting device can be produced in a single firing process.

It is an alternative embodiment that the conductor structure is burned into the already fired, in particular sintered, base material ('post-fired'). As a result, a shrinkage on the conductor structure can be avoided.

The type of burn-in of the conductor structure, whether z. For example, a co-firing process or a post-firing process may be applied depending, among other things, on what kind of paste system is used for the ladder structure.

It is also an embodiment that the conductor structure is printed by means of a screen printing on the (fired depending on the production or not yet fired) substrate. As a result, the conductor structure can be applied in a simple and inexpensive manner.

In the following figures, the invention will be described schematically with reference to an embodiment schematically. In this case, the same or equivalent elements may be provided with the same reference numerals for clarity.

1 shows a sectional side view of a sketch of an LED lamp according to the invention;

2 shows in plan view a detail of a lighting device of the LED lamp according to the invention; and

3 shows the LED lamp according to the invention as a sectional view in front view.

1 shows a sectional side view of a sketch of an LED lamp according to the invention 1 , The LED lamp 1 has a substantially circular cylindrical glass bulb 2 in which longitudinally a linearly elongated lighting device 3 is used. The lighting device 3 has a band-shaped substrate 4 with a thickness of at least 0.5 mm made of a PCA material. On a top 5 of the substrate 4 are (one-sided) several LEDs 6 in a row along the longitudinal extent of the substrate 4 equidistant, ie with an equal pitch d, applied. The pitch distance d is preferably and generally 10 mm to 20 mm in order to achieve a homogeneous light emission.

The light-emitting diodes 6 are over a ladder structure 7 connected to each other, leading from the conductor structure connecting leads (not shown) for power supply to the outside. Not shown, but also attached to the substrate, electronic components such as driver chips, etc. may be present. The conductor structure is in the substrate 4 baked and thus very durable.

By using the PCA material with the thickness of at least 0.5 mm, the substrate can 4 act as a heat sink by being one of the light emitting diodes 6 generated loss heat dissipates quickly and distributed.

The light diodes 6 are designed so that they emit not only in the upper half-space, which is centered around the here perpendicularly upward main emission direction, but also backwards or downwards in the rear or lower half-space, which represents the half-space complementary to the upper half-space. Usual light emitting diodes only shine in the upper half space, but not backwards. The radiation in the rear half space can be achieved by the light-emitting diode 6 at least one lens 8th which has different degrees of filling of a luminous means or phosphor. Additionally or alternatively, the lens 8th be provided with an at least partially reflective mirror layer which is designed so that it forms part of the emitter surface 9 the LED 6 emitted light reflected in the rear half space. Additionally or alternatively, the lens may have a shape that allows a return radiation in the rear half space.

During operation of the lamp 6 the LEDs are shining 6 Light in the upper half space and partly in the lower half space. Light rays L of an exemplary selected LED 6 are shown schematically as arrows. The backward radiated light partially enters the substrate 4 one. That the substrate has a light transmittance of at least 99% and is also diffuse, is in the substrate 4 entering light transmitted with only a slight loss of light and thereby homogenized in its intensity distribution, as indicated by the broadening of the incoming light rays.

The distribution of light distribution in the upper half space and the lower half space depends on the design of the lamp 1 off, z. B. of the proportion of the light-emitting diodes 6 backwards from radiated light. Also, the division of the Light distribution by the nature of the glass bulb 2 be influenced as more exactly in 3 explained.

The lamp 1 For example, can be made so that the lighting device 3 is inserted into a glass tube open on both sides, wherein the two ends of the glass tube are then closed in a known manner, for. B. by merging.

2 shows a top view of a section on the lighting device 3 the LED lamp 1 with two LEDs 6 , The light-emitting diodes radiate in the circumferential direction 6 evenly off.

3 shows the LED lamp according to the invention 1 as a sectional view in front view. The glass bulb 2 may at least partially on its upper surface with an at least partially reflective layer 10 or layer structure, on its inside and / or outside.

The partially reflective layer 10 causes a greater proportion of the emitter area 9 the LED 6 radiated light enters the rear half space, preferably for a homogeneous intensity distribution completely through the substrate 4 , The partially reflective layer 10 For example, it may be a partially transparent and partially reflective layer or layer composite. Alternatively or additionally, the layer 20 be configured as a layered structure having partially translucent (eg uncoated) areas and fully reflective areas, e.g. In an alternating pattern (stripe pattern, checkerboard pattern, ring pattern, etc.).

At the shift 10 can the glass bulb 2 thus highly reflective and otherwise highly translucent designed.

Generally, the lamp can 1 be designed so that it has a respect to their longitudinal direction substantially homogeneous intensity distribution, which enables them in particular as a replacement for a line lamp or fluorescent tube (LED retrofit lamp). Alternatively, the radial light distribution z. B. be designed application-related inhomogeneous.

The lamp 1 For example, it can be used as a mirror lamp to illuminate a mirror. be used, which can be used simultaneously for room lighting.

Of course, the present invention is not on. limited the embodiment shown.

Thus, the substrate may also be constructed of a translucent plastic, for. B. made of PET.

LIST OF REFERENCE NUMBERS

1

Led lamp

2

flask

3

lighting device

4

substratum

5

Top of the substrate

6

led

7

conductor structure

8th

lens

9

emitter area

10

reflective layer

d

pitch distance

L

beam of light

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 20214661 U1 [0003]

Claims (14)

Lighting device ( 3 ), comprising at least one substrate ( 4 ), which is unilaterally with at least one light source ( 6 ), characterized in that the substrate ( 4 ) has a translucent base material having a thermal conductivity of at least 10 W / (m · K). Lighting device ( 3 ) according to claim 1, characterized in that the base material has a light transmittance of at least 95%. Lighting device ( 3 ) according to one of the preceding claims, characterized in that the light source has a radiation angle of more than 180 °. Lighting device ( 3 ) according to one of the preceding claims, characterized in that a lens ( 8th ) of the light source ( 6 ) has different fill levels of a light bulb. Lighting device ( 3 ) according to one of the preceding claims, characterized in that the base material has a thermal conductivity of at least 30 W / m · K. Lighting device ( 3 ) according to one of the preceding claims, characterized in that the substrate ( 4 ) has a thickness of at least 0.5 mm to 2 mm. Lighting device ( 3 ) according to one of the preceding claims, characterized in that the base material is a transparent ceramic material. Lighting device ( 3 ) Claim 7, characterized in that the base material is a PCA material. Lighting device ( 3 ) according to one of the preceding claims, characterized in that the lighting device ( 3 ) several with the at least one light source ( 6 ) equipped substrates ( 4 ) having. Lighting device ( 3 ) according to any one of the preceding claims, characterized in that the substrate ( 4 ) a sintered base material and at least one conductor structure baked thereon ( 7 ) having. Lamp ( 1 ), characterized in that the lamp ( 1 ) at least one lighting device ( 3 ) according to one of the preceding claims, wherein the lighting device ( 3 ) in a flask ( 2 ), in particular cylindrical glass bulb, is introduced. Lamp ( 1 ) according to claim 11, characterized in that the piston ( 2 ) in a radiation direction of the at least one light source ( 6 ) is at least partially mirrored. Method for producing a lighting device ( 3 ) according to claim 9, characterized in that the base material together with the conductor structure ( 7 ) is burned. Method for producing a lighting device ( 3 ) according to claim 9, characterized in that the conductor structure ( 7 ) is baked in the fired base material.

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