AT17476U1 - Motion Control of Lighting Device Components by Microelectromechanical Systems (MEMS) - Google Patents

Abstract

The invention relates to an LED module (1) which has a carrier (2), an LED chip (3) which is mechanically and electrically connected to the carrier (2), and an optical lens unit (5) which is connected to the LED chip (3) is slipped over has. The edge area of the optical lens unit (5) is underlaid on the carrier (2) with a number of electrically controllable MEMS-based micro-actuators (6).

Description

description

MOTION CONTROL OF LIGHTING DEVICE COMPONENTS BY MICROELECTROMECHANICAL SYSTEMS (MEMS)

The invention relates to lighting devices, such as LED modules, whose optical elements (e.g. optical lenses and/or reflectors or reflector elements) are changed in a targeted manner in terms of their position and/or alignment by activation using microelectromechanical systems, in order to optimize the optical properties of the To change device / module specifically.

Known optical systems according to the prior art whose optical properties can be changed in a targeted manner mention the possibility of controlling optical system components using MEMS technology, but either exclusively a rotation of inclined or tilted mirrors (US2011/0249460A1), in particular not in connection with LED-based lighting technology (US2016/0154183A1) or without specifying a specific technical design (EP1459600B1). The change in position of optical lenses compared to the positions of the light sources by MEMS actuators in LED modules is not known.

Lighting devices, such as LED modules, currently use rigid optics in the case of light source-lens optics. An optical lens unit is placed over the light source mounted on a carrier, for example an LED (or several LEDs). The optical lens unit may contain a reflector or reflector parts (e.g. several divergent i.e. concavely arranged parts e.g. on the outside of the optical lens unit) while the lens sits on the reflector, for example. In most such lighting devices, the lens optics are typically located on top of the LED module. Either a lens only covers a single LED element or a lens covers several LEDs that together form a cluster - depending on the LED density on the carrier and the size of the lens. When using an LED lens system, it is extremely important to position both the individual LEDs and the lenses over the LEDs exactly. The light beam emanating from the LED module can then be influenced by changing the distance and/or angle of the LED and lens: for example, a strongly divergent beam or a strongly focused beam can be generated from the normal light beam, as well as the direction of the Beam can be changed.

The invention is therefore based on the object of proposing a simple and inexpensive technology for a lighting device of the above type (e.g. lens via LED on a carrier and with a reflector unit, possibly in combination), with which the positions of the system components can be changed in order to to change the optical properties of the LED module.

[0005] This object is solved by the features of the independent claim. Advantageous developments of the invention are described in the associated subclaims.

[0006] FIG. 1 shows a micromanipulator based on MEMS technology,

[0007] FIG. 2a shows a sectional view of a MEMS actuator (also referred to below as a microactuator) based on a circular semiconductor layer in the form of a flexible silicon nitride membrane.

[0008] FIG. 2b shows a sectional view of the possible bulging of the silicon nitride membrane triggered by electrostatic forces,

FIG. 2c shows the circular silicon nitride membrane with a diameter of one millimeter in a plan view,

[0010] FIG. 3 Z shows, in a sectional view, the application according to the invention of MEMS actuators according to FIGS. 2a to 2c with respect to four adjacent or side-by-side LED modules,

[0011] FIG. 4a shows a top view of a square arrangement of four MEMS actuators (micro-actuators) under the optical lens unit of an LED module fixed on a carrier, each with a spring-based restoring element in between,

[0012] FIG. 45 shows a side view of the interaction between two MEMS actuators (micro-actuators) and the centrally arranged spring-based restoring element,

[0013] FIG. 5a shows a simplified diagram of a 4×5 arrangement of jointly controlled LED modules according to the technology in FIGS. 4a/4b,

Figure 5b shows a schematic of a separate control of possibly different types of LED modules in the corners of the 4x5 arrangement of Figure 5a.

Since a very small change in the position of the optical lens unit 5 or the LED or the LED together with the carrier and reflector unit is sufficient to change the light beam 15 significantly before it emerges from the lens, the present invention proposes using MEMS actuators .

The MEMS technology (referred to as microsystem technology in European-speaking countries) will therefore be briefly described below:

[0017] Microelectromechanical systems (MEMS) (or the technology on which they are based) are defined in that they consist of miniaturized mechanical and electromechanical components which in turn have been produced by microfabrication techniques. The orders of magnitude range from the millimeter range to the nano range, with MEMS technology now overlapping more and more with nanotechnology (in which quantum mechanical phenomena can also be used). MEMS products can be as simple as they contain no moving elements, or they can be extremely complex electromechanical structures, with numerous moving components and integrated circuit-based control. It has been shown that it is extremely advantageous if all micromechanically and microelectronically interacting structures are combined on a single silicon substrate (silicon nitrate wafer), since, for example, cables are no longer necessary, electrical conductor tracks are very short and the required current or the required voltage (the electrical consumption in general) is extremely low.

The most important functional elements of MEMS technology are micro-sensors and micro-actuators. Micro-sensors convert measured mechanical effects into electrical signals (temperature sensors, acceleration sensors, microphones, micro-mirrors, etc.). With micro-actuators, this is usually the other way around, resulting in an immense variety of electromechanical applications.

A possible example given here (see Figure 1) for a micro-actuator is a micromanipulator (engl. Micromanipulator or micro-manipulating device), a device for mechanical interventions on objects with very small dimensions (in the range of a few micrometers or less ). A micromanipulator is used, for example, in microsurgery, in reproductive medicine for cell processing and for positioning the measuring electrode using the patch-clamp technique. Under optical control (e.g. under a microscope), the micromanipulator is used in operations on tissues and cells of living beings. Extremely precise interventions can be carried out using very fine glass capillaries, needles, electrodes and other instruments, usually in a range between 5 μm and 200 μm.

[0020] The micromanipulator "translates" the movements of the human hand, which are far too coarse--relative to the object under examination--into very fine movements of the instruments used, which are controlled mechanically, hydraulically, or electronically. Typical micromanipulators allow movements in all three spatial directions.

Another example of a micro-actuator is the inverse of a semiconductor-based one

Microphone (English MEMS microphone, MEMS micro membrane, see Figures 2a, 2b, 20). By applying only a low voltage to a micromembrane 7 that changes the electrical capacity (Figure 2c, membrane diameter 1mm), which is etched directly onto the silicon wafer, and its readout electronics with a preamplifier and an analog-to-digital converter right next to the membrane 7 is integrated on the wafer in an application-specific integrated circuit (ASIC) (usually as components in CMOS technology), the membrane 7 can be curved on one side (FIG. 2a) or on both sides (FIG. 2b). The arching force is so strong and the arching distance is so large that weights in the range of several hundred grams can be moved (lifted, hoisted or lowered) by a millimeter with only a low power consumption of the system. The good shielding from interference signals and low-cost production mean that these or similar micro-actuators can be used in many areas.

[0022] This also applies to LED technology. According to the present invention, such a controlled MEMS silicon nitrite micromembrane - hereinafter referred to as micro-actuator 6 - is placed on both sides or four sides of the optical lens unit placed on the carrier 2 (substrate, usually a PCB circuit board) of an LED module 1 5 selectively underlaid. The number four is only an example, there can also be more micro-actuators (e.g. five, arranged in a polygon) or fewer, e.g. only three or two.

FIG. 3 shows four LED modules 1 arranged next to one another in a simplified side view. Each LED element 3 sits on the carrier plate 2 on which all LED modules 1 are based. Furthermore, each LED element 3 has an optical lens unit 5 slipped over it or each LED element 3 is surrounded by one. According to FIG. 3, the optical lens units 5 shown have the shape of an inverted truncated cone and should advantageously not touch one another. Shapes other than a truncated cone are also possible. In the further course of the description, the optical lens unit 5 is sometimes simply referred to as a “lens”. For the sake of simplicity, only two micro-actuators 6 are shown for each optical lens unit 5, which are opposite one another. The micro-actuators 6 of the two left-hand LED modules 1 are in a neutral state, i.e. the light beams 15 emitted by the LEDs 3 leave the respective optical lens unit 5 perpendicular to their light source, the respective LED 3.

The situation is different for the third and fourth LED 3 from the left:

The left-hand micro-actuator 6 of the third lens 5 from the left is shown lowered, in contrast to its right-hand counterpart, which is shown neutral. The lens unit 5 of the third LED 3 from the left is thus tilted or inclined to the left, as a result of which the light beam 15 emanating from the LED 3 is also emitted to the left or leaves the lens 5 in a direction pivoted to the left.

With the fourth lens 5 from the left, the situation is exactly opposite to that of the third lens 5: here the right-hand micro-actuator 6 is lowered and the left-hand counterpart is shown as neutral. The optical lens unit 5 is tilted to the right and the light beam 15 leaving the lens 5 is pivoted to the right.

Conceivable - but not shown in Figure 3 - is also a simultaneous parallel lowering or lifting of two corresponding micro-actuators 6, which would change the distance between LED 3 and lens 5 result. In this way, depending on the nature of the lens unit 5, the light beam 15 can be widened or focused.

Are micro-actuators 6 used, which - starting from a middle, neutral position - are vertically movable on both sides (curvature of the membrane 7 up or down or no curvature in the neutral state), and a lens 5, the generates a non-divergent and non-convergent light beam 15 in the neutral position, the light beam 15 leaving the LED 3 can be made divergent or convergent solely by similar (parallel) activation of the micro-actuators 6 .

Mixed states (due to only partial non-parallel movement of corresponding microactuators 6), i.e. pivoting of the light beam 15 with simultaneous divergence or convergence,

are also possible with this technical arrangement according to the invention.

As I said, FIG. 3 is a simplified representation in order to be able to better explain the inventive concept, whereas FIG. FIG. 4a even goes into so much detail that spring-based restoring elements 8 are drawn in each case in the middle between two micro-actuators 6 . This detail is optional and particularly advantageous if the movements of the micro-actuators 6 are to be supported, that is to say an active reset is to be forced or a rapid and precise neutral position of the lens 5 is to be achieved.

Figure 4b shows a side view of the interaction between two micro-actuators 6 and a spring-based restoring element 8 located in the middle between them Game is performed and on the other side of the carrier 2 (on the underside) at a flange 10 ends. Between the underside of the carrier and the flange 10 there is a spring 11 which is pushed centrally over the guide pin 9 and does not affect the play between the carrier 2 and the guide pin 9 .

It is possible to keep the springs 11 in an unstressed state, i.e. without stretching or tension, if the micro-actuators 6 are also in the neutral state (no buckling of the e.g. silicon nitrite membrane 7). In this way, this spring-based restoring principle always guarantees an optically neutral position of the lens 5 in the event that all four micro-actuators 6 are also in the neutral state or return to it.

However, it would also be possible to preload the springs 11 even if the micro-actuators 6 are in the neutral state. It would also be possible to generally preload the springs 11, i.e. independently of the state of the micro-actuators 6. Any combinations are possible.

All four micro-actuators 6 of an LED module 1 can be controlled simultaneously and can influence the direction and shape of the light beam 15 of the associated LED element 3 . While the principle illustrated in FIG. 3 shows only two micro-actuators 6 and thus—apart from divergence and convergence—only allows left-right pivoting, a more general arrangement according to FIGS. 4a and 4b allows the light beam 15 to be pivoted in any direction possible, with simultaneous manipulation of the beam path in its direction (widening or focusing). Theoretically, it would even be conceivable--depending on the complexity of the arrangement and control of all micro-actuators 6--to rotate the light beam 15 of an LED 3 clockwise or counterclockwise on a conical surface. However, the degree of light beam manipulation is limited by the maximum stroke 85 and the arrangement geometry of the respective micro-actuators 6 .

In the figures 5a and 5b it is shown that independently of the electrical supply of an LED array 12, ie a matrix-like arrangement of individual LED modules 1, a further power supply 13 for the sole control of the micro-actuators 6 can be provided . In this case, all micro-actuators 6 can be controlled in the same way or, as already mentioned above, differently, but coordinated with one another.

FIG. 5a shows a simplified diagram of a 4×5 arrangement 12 of jointly controlled LED modules 1 according to the technology of FIGS. 4a/4b. The LEDs 3 shown in the center of an LED module 1 are all supplied by the same voltage source 13, while the microactuators 6 arranged in the square are controlled by a separate control block 14.

Specifically, FIG. 5b schematically shows a separate activation of the four LED modules 1 in the corners of the 4×5 arrangement 12 of FIG. 5a. The aim is to show that separate activation of only individual LED modules 1 or of LED module groups in the entire LED module assembly 12 is possible.

In summary, the present invention provides a cost effective solution

o for a precise position-changing control of the individual lenses 5 of any LED array 12 (matrix-like LED combination),

o for a light beam change of individual LEDs 3 or in groups or in their entirety with regard to direction as well as divergence and convergence,

o to achieve special optical effects and

o for achieving different optical properties of either the entire LED array 12 or individual sub-units.

REFERENCE LIST:

1 LED module 2 carrier/substrate 3 LED chip

5 Optical lens unit / lens

6 MEMS based micro-actuators 7 semiconductor layer (silicon nitrite)

8 Spring based return element 9 Guide pin

10 flange

11 spring / return spring

12 LED array

13 power supply

14 control block

15 light beam

ö maximum stroke of the semiconductor layer

r Diameter of the semiconductor layer (silicon nitrite) (e.g. 1mm)

Claims (10)

Expectations 1. LED module (1) having - a carrier (2), - an LED chip (3) which is mechanically and electrically connected to the carrier (2), - an optical lens unit (5) which the LED chip ( 3) is slipped over, characterized in that the optical lens unit (5) on the carrier (2) with a number of electrically controllable MEMS-based micro-actuators (6) is underlaid in its edge region. 2. LED module (1) according to claim 1, characterized in that the functioning of the micro-actuators (6) is based on the electrically caused warping of a semiconductor layer (7). 3. LED module (1) according to claim 2, characterized in that the semiconductor layer (7) and thus the micro-actuator (6) has a diameter (r) in the millimeter range. 4. LED module (1) according to claim 1 or 2, characterized in that the optical lens unit (5) has a number of spring-based restoring elements (8). 5. LED module (1) according to any one of the preceding claims, characterized in that the micro-actuators (6) are arranged polygonally and in each case a spring-based return element (8) is positioned between two micro-actuators (6). 6. LED module (1) according to claim 4 or 5, characterized in that the spring-based restoring element (8) has a guide pin (9) which is fixed at one end on the underside of the optical lens unit (5), protrudes through the carrier (2) with sufficient play and has a flange (10) at its other end at a distance from the underside of the carrier (2), the guide pin (9) between the underside of the carrier (2) and the flange (10 ) a spring (11) is pushed on. 7. LED module (1) according to claim 6, characterized in that in the neutral position of the micro-actuators (6), the spring (11) of the restoring element (8) is not tensioned. 8. LED module (1) according to claim 6, characterized in that in the neutral position of the micro-actuators (6), the spring (11) of the restoring element (8) is prestressed. 9. LED module (1) according to one of the preceding claims, characterized in that it is part of a matrix-like LED array (12), the control of the LED chip (3) and the control of the micro-actuators ( 6) done separately. 10. LED array (12) having a number of LED modules (1) according to any one of the preceding claims, characterized in that the individual LED modules (1) differ in their structure individually and / or in groups. 4 sheets of drawings