WO2008142621A1

WO2008142621A1 - A light projecting device comprising an array of led's

Info

Publication number: WO2008142621A1
Application number: PCT/IB2008/051928
Authority: WO
Inventors: Wolfgang O. Budde; Volkmar Schulz; Harald J. G. Radermacher
Original assignee: Philips Intellectual Property & Standards Gmbh; Koninklijke Philips Electronics N.V.
Priority date: 2007-05-21
Filing date: 2008-05-16
Publication date: 2008-11-27
Also published as: TW200914761A

Abstract

This invention will introduce a light projecting device (1), the light projecting device (1) comprises a plurality of light emitting diodes (LED) (12) configured in an array; wherein at least the majority of said plurality of LEDs (12) have light emission angles up to 20-, and wherein each LED is fixed in the array in such manner that it is able to emit light with different direction of its light beam center in relation to light beam centers of a majority of the other LEDs.

Description

A light projecting device comprising an array of LEDs

FIELD OF INVENTION

The invention relates to light sources, more precisely to a LED based projection lamp.

TECHNICAL BACKGROUND

Expressing a certain mood and creating a certain atmosphere based on the light is a complicated task when realized with "normal" lamps. A certain number of light sources have to be arranged to illuminate the desired area. The optical output of the light sources has to be controlled accurately to achieve the desired color distribution. Nevertheless, the viewing angle of normal lamps is usually very large, which complicates the creation of a spatial color distribution.

The JP 2000285709 A shows a LED array which responds to sounds. The LED color corresponds to the frequency or wavelength of an acoustic signal.

A known device, which is capable of producing a very accurate spatial color distribution, is a high resolution image projector, which might use LCD panels or DLP -techno logy, to provide a huge number of individual light pixels in the range of several hundreds of thousands.

Unless it might be possible to get the desired light effect with the techniques mentioned above, there are some drawbacks: Providing a narrow light beam of each lamp is a quite complicated task and result in large lamps due to their optics. To be able to change the projected scene later on either the lamps have to rearranged, or there has to be huge number of devices so that any area can be lit in any color. This would result in high costs. The control of all these devices including the addressing of each individual lamp is a complicated task. With a high resolution image projector, there are some drawbacks, too.

A problem for both systems is the efficiency, especially at low light levels, the efficiency of most normal light sources decreases. In addition, the color depends on the power level. With the image projector, the color is stable over the power level, but this is achieved by blocking the unwanted light, which decreases efficiency even more, the lower the light level. In addition, image projectors usually have a fan, which produces some noise. High intensity is achieved with gas discharge lamps, which have a limited lifetime. Especially for a device, which should provide some background illumination all the time, this is very critical.

SUMMARY OF THE INVENTION

It may be desirable to provide a more energy efficient light projecting device which is easy to control and enables the use of a low-cost feedback system.

This need may be met by a light projecting device which comprises a plurality of light emitting diodes (LED) configured in an array; wherein at least the majority of said plurality of LEDs have light emission angles up to 20°, preferably between 3° to 12° and wherein each LED is fixed in the array in such manner that it is able to emit light with different direction of its light beam center in relation to light beam centers of a majority of the other LEDs, according to the independent claim.

In other words, the present invention describes an LED based atmosphere creation device with interactive user interface. It is intended as a calm light source, which produces static or dynamic background illumination to create a certain mood or atmosphere. LEDs with narrow emission angle are used to gain a spatially separated light effect of each individual LED. The light effects of the LEDs do not have to be round spots or perfect squares. LEDs with especially shaped light distributions can increase the attractiveness of the device. As a benefit, only these LEDs are activated which are used to provide the desired light effect. No energy is wasted. Due to the relatively low number of LEDs, the device has less parameter, hence it is easy to control. This enables the use of a low cost interactive feedback system, with acoustical or optical devices, such as microphones or cameras as described later. The LED based projection device of the invention offers a unique combination of low- level illumination, low-resolution display and interactive user interface. In the following, further exemplary embodiments of the light projecting device will be described. However, these embodiments apply also to a light projecting system.

According to claim 1 of the present invention a light projecting device comprising a plurality of LEDs configured in an array; wherein at least the majority of said plurality of LEDs have light emission angles up to 20° and wherein each LED is fixed in the array in such manner that it is able to emit light with different direction of its light beam center in relation to light beam centers of a majority of the other LEDs is provided. The said light emission angles may be based on the shape of the LEDs themselves, or alternatively based on LEDs with wider emission angle but associated optical devices such as focus lenses, or an integrally formed plurality of focus lenses which may covers the said array.

As said in other words before, the invention describes a device, which is located below the known possibilities of a display projector but above the capabilities of a set of lamps. It is intended as a calm light source, which produces some background illumination to create a certain mood or atmosphere. LEDs with narrow emission angles are used, so there is a spatial separation of the light effect of each individual LED. Several different LED colors can be used to have a full color display. Preferably, a combination of red, green and blue LEDs may be used, which might be enhanced by using further LED colors such as warm white, amber, cyan, etc. The distribution of the light effects of the different colors can be homogeneous or inhomogeneous. The number of LEDs determines the resolution. Together with the emission angle of the LEDs, and the desired "pixel" overlap, the number of LEDs determines the viewing angle. The light effects of the LEDs do not have to be round spots or perfect squares. LEDs with especially shaped light distributions as square spots with a shadow in the center, rhombical spots or spots with circular light and shadow zones can be used to create certain optical effects.

As a benefit with respect to a high resolution projector, only these LEDs are activated which are used to provide the desired light effect. No optical energy (corresponding to electrical energy) is wasted by shielding some potion of the light to dim it down to the required level. Due to the low number of LEDs compared to the pixel count of an image projector, the system has less parameter, hence it is easy to control. This enables the use of a low cost interactive feedback system: A camera can be used to capture at least a part of a projected scene. Positioning the camera at nearly the same place as the light projecting device allow a good correlation between the captured light effect and the corresponding LEDs, which is responsible for projection in this area. As a result, the complexity of the control system is further reduced. This allows an interactive user interface to control the light distribution of the light projecting device. The user might have an additional light source, similar to a torch, and can "paint with light" on the projection area. With some image processing software, the LEDs are controlled in a way to represent the captured light distribution. Using a multi-color light source or some other modulation techniques, the user can select different colors and options like adding or erasing colors at different locations in the said area. Of course, the projection of predefined scenes, a remote control access to the system or the projection of low- resolution versions of a picture - which might be presented to the camera or electronically transmitted to the system - is also possible. In a further embodiment, the image processing system should be able to capture the important structures in the target rather than just averaging the color in a certain area to calculate the setting for the LEDs, lighting this area. Preferably, packaged LEDs with small viewing angle or arrangements of

LED chips with appropriate optic devices such as lenses to produce a small viewing angle and mechanically arranged in an array are used in a preferred embodiment of the present invention. Depending on the number of LED chips, the material of the optic device might be a conventional glass or (molded) plastic lens or might be based on photonic structures. The LEDs are mounted in a way that they emit into different directions. Preferably, packaged red, green and blue LEDs with viewing angles of 8° or 15° are used in a further embodiment. They are preferably arranged in an x-y array. Depending on the position within the array, the LEDs are aligned into certain direction. In a further embodiment of the invention, the alignment in one direction is achieved by bending the LED wires, the alignment in the other direction is realizable by bending the printed circuit board. As a result, the light effect of each LED has a certain position on the projection surface. The LEDs from one triplet (red, green and blue) are aligned to the same pixel area in a preferred embodiment. Since there are enough triples, a larger projection area can be covered with individually controllable pixels. The invention could be realized e.g. with 8° LEDs in an 8x8x(RGB) matrix. Driving the LEDs with different currents or different duty cycles in an further embodiment of the present invention allows producing the desired color distribution within the projection area.

According to a further embodiment of the present invention the light projecting device projects light beam patterns with an overall solid angle covering a rectangular area.

According to a further embodiment of the present invention the solid angle covering the rectangular area is vertically extended between 30° and 90°, and horizontally extended between 45° and 360°.

According to a further embodiment of the present invention the light projecting device further comprises a controller to selectively power groups of the plurality of LEDs to provide different light beam patterns.

According to a further embodiment of the present invention the controller is controllable by an acoustical, optical, remote control and/or processor device.

According to a further embodiment of the present invention the acoustical device is a microphone.

According to a further embodiment of the present invention the optical device is a camera.

A camera can capture the projected scene to provide a feedback path or as an input for target data or for an interactive user interface as a processor device or a remote control device combining the feedback information as well as the target generation as described above.

According to a further embodiment of the present invention the light projecting device is able to project predefined scenes of light beam patterns.

According to a further embodiment of the present invention the light projecting device comprises a storage device for storing data of predefined scenes of light beam patterns. According to a further embodiment of the present invention the light projecting device is adapted to illuminate at least a wall or a ceiling of a room.

According to a further embodiment of the present invention a set of a plurality of light projecting devices is claimed, wherein the light projecting devices are combined such that rectangular area of each light beam patterns is neighboured to or overlapped with light beam patterns of a neighboured light projecting device.

Thus, in other words, the set can be build modular, having segments, which project into a certain solid angle. These segments can be stacked together to cover larger areas. As an example, four modules with each 10x5(RGB) LEDs covering 90°x45° can be combined to a 360°x45° module allowing to project a coloured band all the walls of a room. The same four modules could also be aligned to the same 90°x45° region with overlapping pixel areas to increase the brightness of the projected scene. Using a master-slave control concept, only one module has to be equipped with a camera provides the user interface, while the other modules extend the projection area, the resolution or the brightness based on the data generated by the master.

According to a further embodiment of the present invention a light projecting system, comprises a light projecting device, a camera, a remote control device and/or a computer device, wherein the camera captures a) the light beam patterns projected by the light projecting device and/or b) other optical contend and transfer image information to the controller of the projection system. This optical loop can be used as a closed loop feedback system or as a user interface or a combination of both.

According to a further embodiment of the present invention a light projecting system comprises a light projecting device according to claim 1, a camera and a controller device, wherein the camera is adapted to capture images and to transfer image data of said images to the controller device, wherein the controller device is adapted to use said image data to generate control signals and to transfer said control signals to the light projection device, and wherein the light emission of the plurality of light emitting diodes of the light emitting device is controllable by said control signals.

According to a further embodiment of the present invention an object area of an image captured by the camera overlaps at least partially the area of the light beam patterns projected by the light projecting device. According to a further embodiment of the present invention a light projecting method uses a light emitting device according to claim 1 , a camera and a controller device, and comprises capturing an image of an object with the camera, transferring image data of said image to the controller device, generating control signals by the controller device using the transferred image data and controlling the light emission of the light projecting device by said control signals.

According to a further embodiment of the present invention a light projecting method further comprises modifying the light emission of the light projecting device by manipulating the incident light pattern captured by the camera or based on further data set to the camera. The further data may be sound signas or data delivered from an external source.

According to a further embodiment of the light projecting method manipulating of the incident light pattern is based on a user operation, wherein the user operation is preferably moving a visible object trough a space spanned by an aperture angle of an objective of the camera.

The object of the present invention can be used as a decorative lighting object, to provide background-illumination and as a kind of creative lamp, where people can determine their own light effect in an easy and interactive way.

Equipped with an array of microphones, it could also act as an optical feedback based on acoustical information. Thus, depending on the direction or the characteristic of the sound, the device will show a combination of a set of pictures. E.g. it could be used in open-plane offices as a noise indicator.

These and other aspects of the present invention will become apparent from and elucidated with reference to the embodiment described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described in the following, with reference to the following drawings. Fig. 1 shows schematically a light projecting device according to the invention. Fig. 2 shows schematically a side view of a light projecting system with an other embodiment of a light projecting device.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The illustration in the drawing is schematically. Fig. 1 shows an exemplary embodiment of a claimed light projecting device 1. The device 1 is depicted in a sectional view and uses a plurality of LEDs 2 that are mounted on a Printed Circuit Board 3 (PCB) in a way that they emit into different directions. The PCB 3 is slightly bended to a non-planar 3D-PCB. In the shown embodiment every three LEDs 2 with different colors are combined to a group 4 which projects every three LED light beams to one spot 5 or "pixel" on an object 6, precisely a wall. The light beams of the LEDs 2 may have the colors red, green, blue, amber, cyan and white in the shown embodiment. Each illuminated area of the spot 5 forms an overlap section 7 with the illuminated area neighbor spots on the wall.

Fig. 2 depicts a schematically side view of a light projecting system 8. The system 8 comprises a light projecting device 1 ', a camera 9 and a controller device 10. In the shown embodiment the devices and the camera 9 are mounted on a plane PCB 3', and are interconnected to each other. The camera 9 is adapted to capture images 11 and to transfer image data of said images 11 to the controller device 10. Further, the controller device 10 is adapted to use said image data to generate control signals and to transfer the control signals to the light projection device 1 '. Thus, the light emission 12 of the plurality of light emitting diodes 2' of the light emitting device 1 ' is controllable by said control signals. Further, according to Fig. 2 the image 11 captured by the camera 9, which is in fact a section 15 of a wall 13 overlaps at least partially an area 14 of the light beam patterns projected by the light projecting device 1 '. As in Fig. 1 every three LEDs 2' with the colors red green and blue are combined to a group 4' which projects every three LED light beams 16 to one spot 5' or "pixel" on the wall 13.

With the shown system 8 it is easily possible to modify the light emission of the light projecting device 1 ' by manipulating the incident light pattern associated with image 11 captured by the camera 9. One option to modify the light emission is to move a visible object as the hand of a user trough the space 18 spanned by an aperture angle of an objective 17 of the camera 9. Alternatively, a pocket lamp could be used to illuminate section 15 of the wall 3.

It should be noted that the term "comprising" does not exclude other elements or steps and the "a" or "an" does not exclude a plurality. Also elements described in association with different embodiments may be combined.

Claims

CLAIMS:

1. A light projecting device, the light projecting device comprising: a plurality of light emitting diodes (LED) configured in an array; wherein at least the majority of said plurality of LEDs have light emission angles up to 20°, preferably between 3° to 12°; wherein each LED is fixed in the array in such manner that it is able to emit light with different direction of its light beam center in relation to light beam centers of a majority of the other LEDs.

2. The light projecting device according to claim 1, wherein the light projecting device projects light beam patterns with an overall solid angle covering an area, preferable a rectangular area.

3. The light projecting device according to anyone of the preceding claims, wherein the solid angle covering the preferably rectangular area is vertically extended between 30° and 90°, and horizontally extended between 45° and 360°.

4. The light projecting device according to anyone of the preceding claims, further comprising: a controller to selectively power groups of the plurality of LEDs to provide different light beam patterns.

5. The light projecting device according to claim 4, wherein the controller is controllable by an acoustical, optical, remote control and/or computer device.

6. The light projecting device according to claim 5, wherein the acoustical device is a microphone.

7. The light projecting device according to claim 5, wherein the optical device is a camera.

8. The light projecting device according to anyone of the preceding claims, wherein the light projecting device is able to project predefined scenes of light beam patterns.

9. The light projecting device according to anyone of the preceding claims, further comprising: a storage device for storing data of predefined scenes of light beam patterns.

10. The light projecting device according to anyone of the preceding claims, wherein the light projecting device is adapted to illuminate at least a wall or a ceiling of a room.

11. A set of a plurality of light projecting devices according to anyone of the preceding claims, wherein the light projecting devices are combined such that the preferably rectangular area of each light beam patterns is neighboured to or overlapped with light beam patterns of a neighboured light projecting device.

12. A light projecting system, the light projecting system comprising: a light projecting device according to claim 1; a camera; a controller device; wherein the camera is adapted to capture images and to transfer image data of said images to the controller device; wherein the controller device is adapted to use said image data to generate control signals and to transfer said control signals to the light projection device; and wherein the light emission of the plurality of light emitting diodes of the light emitting device is controllable by said control signals.

13. The light projecting system, according to claim 12, wherein an object area of an image captured by the camera overlaps at least partially the area of the light beam patterns projected by the light projecting device.

14. Light projecting method, the method using a light emitting device according to anyone of claims 1 to 10, a camera and a controller device, the method comprises the following steps: capturing an image of an object with the camera; transferring image data of said image to the controller device; generating control signals by the controller device using the transferred image data; controlling the light emission of the light projecting device by said control signals.

15. The light projecting method according to claim 14, further comprising the step: modifying the light emission of the light projecting device by manipulating the incident light pattern captured by the camera.

16. The light projecting method according to claim 15, wherein manipulating of the incident light pattern is based on a user operation; wherein the user operation is preferably moving a visible object trough a space spanned by an aperture angle of an objective of the camera and/or applying light from a light source to the object captured by the camera.