GB2605801A

GB2605801A - Light-emitting diodes

Info

Publication number: GB2605801A
Application number: GB2105257.6A
Authority: GB
Inventors: Charles Plowman Edward
Original assignee: Disguise Technologies Ltd
Current assignee: Disguise Technologies Ltd
Priority date: 2021-04-13
Filing date: 2021-04-13
Publication date: 2022-10-19
Also published as: GB202105257D0; WO2022219335A1

Abstract

An LED comprising an LED chip 101 for emitting light, an optical element 104 for collimating light rays 102 of the emitted light, and a first microelectromechanical system, MEMS, actuator 103a for displacing the optical element 104 relative to the LED chip 101 so as to control the light emitted by the LED chip 101. The MEMS actuator 103a may be configured to tilt, stretch, compress or linearly move the optical element 104. There may be a second MEMS actuator 103b at the opposing end of the optical element 104. The optical element 104 may be a lens or a flexible reflective component. The lens may be engaged by four equidistant MEMS actuators. The central region of the reflective component may be anchored. Each MEMS actuator may have a counteracting spring. An array of such LEDs controlled independently of one another to form a display is also claimed.

Description

Light-Emitting Diodes [0001] The present disclosure relates to Light-Emitting Diodes (LEDs), an array of said LEDs, and a display of said arrays.

BACKGROUND

[0002] A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. LEDs have a great range of applicability due to their low energy consumption, smaller size and longer lifetime. For example, LEDs can be used as indicator lamps, room and outdoor area lighting, horticultural grow lights and automotive headlamps.

Another example of LEDs is that they can form an LED display which uses an array of LEDs, wherein each LED acts as pixel for a video display. Such an LED display can be used as display boards for advertisement, public information and also as LED video walls in the video, tv and film industry instead of a green screen.

[0003] Typically, an LED comprises an LED chip having an LED element, wherein the LED chip is connected to a power source. The LED element comprises a material that emits light as current flows through it and the colour of the light depends on the material used. It is known to provide LED chips having more than one LED element wherein each LED element comprises a different material such that a range of colours can be achieved. For example, RGB LED chips comprise red, green and blue light-emitting LED elements, each of which comprises a different material. Thus, by mixing the light emitted by the three LED elements a wide range of colours can be obtained. Typically, a lens can be used to focus the light emitted from the LED chip.

BRIEF SUMMARY OF THE DISCLOSURE

[0004] According to the present disclosure, there is provided a light-emitting diode, LED, comprising an LED chip for emitting light, an optical element for collimating light rays of the emitted light, and a first microelectromechanical system, M EMS, actuator for displacing the optical element relative to the LED chip so as to control the light emitted by the LED chip.

[0005] The LED enables the focal length of the optical element to be altered such that the light can be focused and diffused, and/or the direction of the light emitted can be controlled.

[0006] The MEMS actuator may be configured to displace the optical element by moving the optical element towards and/or away from the LED chip, tilting the optical element relative to the LED chip, and/or stretching and/or compressing the optical element in a direction parallel to the LED chip.

[0007] The LED may comprise a plurality of MEMS actuators, wherein the MEMS actuators may be configured to displace the optical element by moving the optical element towards and/or away from the LED chip, tilting the optical element relative to the LED chip, and/or stretching and/or compressing the optical element in a direction parallel to the LED chip.

[0008] In one example, the optical element is a lens and the LED further comprises a second MEMS actuator, the first and second MEMS actuators being configured to engage the lens at opposing ends so that the first and second MEMS actuators are operable to move the lens in a direction towards and/or away from the LED chip and/or tilt the lens relative to the LED chip.

[0009] In one example, the optical element is a lens and the LED further comprises a second MEMS actuator, the first and the second MEMS actuators being configured to engage the lens at opposing ends so that the first and second MEMS actuators are operable to stretch and/or compress the lens in a direction parallel to the LED chip.

[0010] In one example, the optical element is a flexible reflective component and the LED further comprises a second MEMS actuator, the first and the second MEMS actuators being configured to engage the reflective component at opposing ends so that the first and second MEMS actuators are operable to stretch and/or compress the reflective component in a direction parallel to the LED chip.

[0011] In one example, the optical element is a flexible reflective component and the LED further comprises a second MEMS actuator, the first and the second MEMs actuators being configured to engage the reflective component at opposing ends so that the first and second MEMS actuators are operable to move the reflective component in a direction towards and away from the LED chip and/or tilt the flexible reflective component relative to the LED chip.

[0012] A central region of the reflective component may be anchored such that its location is fixed regardless of the reflective component being stretched, compressed and/or tilted by the first and second M EMS actuators.

[0013] The LED may further comprise a third a fourth MEMS actuator, wherein the first, second, third and fourth MEMS actuators are configured to engage the same surface of the lens at an equidistance therebetween, the MEMS actuators being operable to move the lens in a direction towards and/or away from the LED chip and/or tilt the lens relative to the LED chip [0014] The LED may further comprise a spring associated with each MEMS actuator, the spring being configured to counteract the movement of its associated MEMS actuator.

[0015] The LED chip may be controlled by a first circuitry and the MEMS actuator(s) may be controlled by a second circuitry.

[0016] According to another aspect of the present disclosure, an array of LEDs is provided. The LEDs are in accordance to any configuration or combination thereof as descried above.

[0017] In the array, the MEMS actuator(s) for each LED may controlled independently of one another.

[0018] According to another aspect of the present disclosure, a display is provided. The display comprises a plurality of arrays as described above. The arrays may be controlled independently of one another.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Various features of the present disclosure will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate features of the present disclosure, and wherein: [0020] Figure la is a schematic illustration of an LED according to the present disclosure; [0021] Figure lb is another schematic illustration of the LED of figure la; [0022] Figure 2a is a schematic illustration of another LED according to the present

disclosure;

[0023] Figure 2b is another schematic illustration of the LED of figure 2a; [0024] Figure 3a is a schematic illustration of another LED according to the present disclosure; [0025] Figure 3b is another schematic illustration of the LED of figure 3a; [0026] Figure 4a is a schematic illustration of another LED according to the present disclosure; [0027] Figure 4b is another schematic illustration of the LED of figure 4a; [0028] Figure 5 is a schematic illustration of another LED according to the present

disclosure;

[0029] Figure 6a is a schematic illustration of another LED according to the present disclosure; [0030] Figure 6b is another schematic illustration of the LED of figure 6a; [0031] Figure 7 is a schematic illustration of a circuitry for controlling an LED.

[0032] Figure 8a is a schematic illustration of an array of LEDs according to the present disclosure; [0033] Figure 8b is another schematic illustration of the array of figure 8a; [0034] Figure 9 is a schematic illustration of a display according to the present disclosure.

DETAILED DESCRIPTION

[0035] In the following description, for purposes of explanation, numerous specific details of certain examples are set forth. Reference in the specification to "an example" or similar language means that a particular feature, structure, or characteristic described in connection with the example is included in at least that one example, but not necessarily in other examples.

[0036] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0037] Aspects of the present disclosure relate to a light light-emitting diode (LED) comprising an LED chip for emitting light, an optical element for collimating light rays of the emitted light, and a first microelectromechanical system (MEMS) actuator for displacing the optical element relative to the LED chip so as to control the light emitted by the LED chip.

[0038] By displacing the optical element relative to the LED chip the light emitted can be controlled in that the focal length of the optical element can be altered such that the light can be focused and/or diffused, and/or the direction of the light emitted can be controlled.

[0039] In other aspects of the present disclosure, there is provided an array of the LEDs where the light emitted can be controlled. This enables the light output of the LEDs to be grouped or aligned along a given path to increase the intensity of light output. Additionally, an array of LEDs as known from the prior art that is viewed from an angle other than at 90 degree causes chromatic differences in the colour and intensity of the light seen. The array of LEDs according to the present disclosure reduces the chromatic differences in colour and intensity when viewed from an angle other than 90 degrees, thus the light and/or image projected by an array of LEDs according to the present disclosure can be viewed several angles without the drawbacks associated with the prior art. This is particularly useful for use in mixed reality settings such as virtual production stages in the creative industry where panels of arrays of LEDs may be used as it would reduce complex discontinuities in the observed colour and light intensity that is captured by the moving film camera.

[0040] In yet another aspect of the present disclosure, there is provided a display comprising arrays of the LEDs where the light emitted can be controlled. The display can be configured such that each LED can be controlled individually at high field rates forming an effective volumetric light field. Additionally, viewers looking at the display or within the display volume would see an image set closest to the visually correct portion of the volumetric scene for their point of view. Furthermore, such a display would also enable a single observer to see stereo separation creating a multi-observer volumetric display.

[0041] An LED according to the present disclosure will now be described. The LED comprises an LED chip for emitting light, and an optical element for collimating light rays of the emitted light. The LED further comprises a first microelectromechanical system (MEMS) actuator for displacing the optical element relative to the LED chip for controlling the light emitted by the LED chip.

[0042] Additional features of the LED will now be described and it should be appreciated that any of the below described features may be combined such that the light emitted by the LED chip can be controlled.

[0043] The LED chip may comprise at least one LED element formed from a semiconductor material capable of emitting light when current is passed through it. The LED chip may be any suitable LED chip capable of emitting light, for example, it may be a RGB LED chip, or a LGB-FW LED chip. The LED chip is configured to be electrically connected.

[0044] The optical element may be a lens or a reflective component such as a mirror. The optical element may also comprise a lens embedded or fixed to a supportive structure.

The optical element may be rigid or flexible such that it can be manipulated by the MEMS actuator. The optical element may be located above the LED chip as shown in figures la to 2b or alternatively it may be located below the LED chip as shown in figures 3a, 3b, 6a, and 6b.

[0045] The MEMS actuator is a device that can convert electrical energy into mechanical motion. The MEMS actuator may be formed of silicon, for example it may be fabricated out of doped single crystal silicon or polysilicon. The LED may comprise a single MEMS actuator or a plurality of MEMS actuators depending on the desired displacement of the optical element. In one example, the MEMS actuator is ring-shaped such that a single MEMS actuator can be used to displace the optical element. In another example, the LED comprises at least two MEMS actuators exerting force on the optical element in order to displace it. In one example, the LED may further comprise a spring associated with each MEMS actuator, wherein the spring is configured to counteract the movement of its associated MEMS actuator. It should be understood that in this disclosure, MEMS actuator(s) may be any suitable MEMS actuator including electrostatic, magnetic, piezoelectric or thermostatic MEMS actuators.

[0046] In one example, the MEMS actuator or the plurality of MEMS actuators are configured to displace the optical element by moving the optical element towards and/or away from the LED chip, and/or tilting the optical element relative to the LED chip, and/or stretching and/or compressing the optical element in a direction parallel to the LED chip. If a single MEMS actuator is used, a ring-shaped MEMS actuator can be used to move the optical element towards and/or away from the LED chip. In order to achieve tension, compression and/or tilting of the optical element, a single MEMS actuator and an anchor at the opposing side to the single MEMS actuator can be used. If a plurality of MEMS actuators are used, the MEMS actuators can be positioned at opposing ends of the optical element to one another as will be appreciated from figures la to 6b so as to achieve any of, or a combination thereof, moving, filling, stretching and/or compressing the optical element.

[0047] In one example of the LED, the optical element is a lens and the LED further comprises a second MEMS actuator such that the first and the second MEMS actuators are configured to engage the lens on the same surface but at opposing ends. In this way the first and second MEMS actuators can move the lens in a direction towards and/or away from the LED chip and/or tilt the lens relative to the LED chip. By moving the lens away from the LED chip the light emitted by the LED chip becomes more focused and by moving the lens towards the LED chip the light becomes more diffused. By tilting the lens relative to the LED chip, the direction of the light can be controlled.

[0048] In another example, the MEMS actuators are configured to stretch and/or compress the lens in a direction parallel to the plane of the LED chip. In other words, the MEMS actuators can apply tension and/or compression to the lens. It should be understood that the LED can also be configured such that the lens can be stretched and/or compressed in combination with being moved in a direction towards and/or away from the LED chip and also in combination with the lens being tilted. This can be achieved by the use of one set of MEMS actuators configured to move the lens in a direction towards and away from the LED chip and/or tilt the lens relative to the LED chip, and another set of MEMS actuators configured to stretch and/or compress the lens.

[0049] In another example of the LED, the optical element is a flexible reflective component such as a flexible mirror and the LED further comprises a second MEMS actuator, such that the first and second MEMS actuators are configured to engage the reflective component on the same surface but at opposing ends. This enables the first and second MEMS actuators to move the reflective component in a direction towards and/or away from the LED chip and/or tilt the flexible reflective component relative to the LED chip. By moving the flexible reflective component away from the LED chip the light emitted by the LED chip becomes more diffused and by moving the flexible reflective component towards the LED chip the light becomes more focused. By tilting the flexible reflective component relative to the LED chip, the direction of the light can be controlled. It should be understood that if the LED is configured to only control the focus and diffusion of the light and a reflective component is used, then it may be rigid or flexible.

[0050] In another example, the MEMS actuators may be configured to stretch and/or compress the flexible reflective component in a direction parallel to the LED chip. In other words, the MEMS actuators can apply tension and/or compression to the flexible reflective component. It should be understood that the LED can also be configured such that the flexible reflective component can be stretched and/or compressed in combination with being moved in a direction towards and/or away from the LED chip and also in combination with the flexible reflective component being tilted. This can be achieved by the use of one set of MEMS actuators configured to move the flexible reflective component in a direction towards and/or away from the LED chip and/or tilt the flexible reflective component relative to the LED chip, and another set of MEMS actuators configured to stretch and/or compress the flexible reflective component.

[0051] Wien the optical component is a flexible reflective component then a central region of the reflective component may be anchored such that its location is fixed regardless of the flexible reflective component being stretched, compressed and/or tilted as described above by the MEMS actuator or actuators.

[0052] In any of the above described examples, there may be four MEMS actuators configured to move and/or tilt the optical element. The MEMS actuators may engage the optical element on the same surface and be located at an equidistance relative to other.

[0053] The LED chip may be controlled by a first driver or circuitry and the MEMS actuator(s) may be controlled by a second driver or circuitry. The first and the second driver may be separate independent drivers.

[0054] In one example, an array of LEDs as described above may be provided. In such an array, the MEMS actuator(s) for each LED may be controlled independently of one another.

[0055] In another example, a display comprising a plurality of the above described arrays may be provided. In such a display, the MEMS actuator(s) for each LED or each array may be controlled independently of one another.

[0056] Examples of how the above described LED, array of LEDs and display can be implemented will now be described in detail with reference to the drawings.

[0057] Figures la and lb illustrate an example of an LED 100 for controlling light emitted by an LED chip according to the present disclosure. The LED 100 comprises an LED chip 101 with three LED emitters red, green and blue, thus the LED chip may also be referred to as an RGB LED chip. The LED chip 101 is connected to a power source (not shown) and when current flows through the LED chip, the LED emitters emit light. It should be appreciated that any other LED chip can be used, for example, an RGB+W chip. The LED 100 further comprises an optical element such as a lens 104 which is configured to collimate the light rays into a controlled light beam or light cone 102, the lens can also focus and diffuse the light. In this example, the lens 104 is located above the LED chip 101. The lens may be rigid or flexible. The optical element may also comprise a supportive structure such that the lens 104 is embedded or fixed to the supportive structure as shown in figure 5.

[0058] The LED 100 further comprises a first and a second MEMS actuator 103a, 103b configured to displace the lens 104 by moving the lens towards and/or away from the LED chip 101 so as to control the light emitted by the LED chip. This is achieved by the MEMS actuators 103a, 103b being electrically connected to a power source and configured to convert an electric current into a mechanical output. The MEMS actuators 103a, 103b are located below the lens 104 such that they engage the same side of the lens 104. Additionally, the MEMS actuators 103a, 103b are positioned at opposing ends of the lens 104 such that when the MEMS actuators 103a, 103b are deactivated (no electric current is applied), the lens is nearer or closer to the LED chip 101 as shown in figure la, and when the MEMS actuators 103a, 103b are activated by receiving an electric current they move the lens 104 away from the LED chip 101 in a linear motion along a z-axis as is illustrated in figure 1 b. When the lens 104 is moved away from the LED chip 101 by the MEMS actuators 103a, 103b being activated (receiving electric current) or by receiving more electric current if already activated, the focal length of the lens is altered such that the focal length is lengthened. This results in the light beam 102 being more focused as is illustrated by the light beam 102 in figure lb. When the lens 104 is then moved towards the LED chip 101 again by the MEMS actuators receiving less electric current or by being deactivated (receiving no electric current) the light beam 102 becomes more diffused as illustrated in figure la. Thus, the light emitted by the LED 100 can be controlled in the sense of being focused and diffused.

[0059] It should be understood that the MEMS actuators 103a, 103b may comprise two states, an "activated state" corresponding to an "on state" and a "deactivated state" corresponding to an "off state", where in the activated state the MEMS actuators receive electric current and in the deactivated state the MEMS actuators receive no electric current. That is, the MEMS actuators 103a, 103b have two mechanical outputs such that the lens 104 can be in held in two positions; nearer to and further away from the LED chip 101, and be transitioned therebetween as the electric current is switched on/off. In an alternative example, the MEMS actuators may be configured to have several mechanical outputs during the active state depending on the amount of electric current received. For example, by increasing the electric current received by the MEMS actuators during the activated state, the mechanical output increases. Similarly, by reducing the electric current received by the MEMS actuators, the mechanical output decreases. This enables the lens to be held in a range of distances relative to the LED chip where the minimum and maximum distances are dependent on the configuration of the MEMS actuators. This means that the emitted light can be continuously changed from focused to diffused.

[0060] The LED 100 may further comprise a spring 105a, 105b associated with each MEMS actuator. The springs 105a, 105b counteract the force of its associated MEMS actuator 103a, 103b such that when the MEMS are deactivated (electric current is no longer supplied to the MEMS actuators) the springs assist in pulling the MEMS actuators 103a, 103b back to their original configuration as shown in Figure la. It should be understood that the springs are optional as in one example the LED 100 does not comprise any springs and the MEMS actuators 103a, 103b revert to their original configuration upon current no longer being supplied.

[0061] The MEMS actuators 103a, 103b are configured symmetrically such that their mechanical output is the same in terms of direction, distance and time. Thus, the lens 104 is configured to move away from and towards the LED chip 101 whilst being kept in the same plane. In an alternative example, the mechanical output of the MEMS actuators 103a, 103b can be different such that one end of the lens 104 is moved further away from the LED chip than the opposing end of the lens. This causes the light beam to be angled or tilted relative to the LED chip 101. This type of configuration is described below in more detail with reference to figures 4a an 4b.

[0062] It should be understood that the LED 100 is not limited to a first and a second MEMS actuator. For example, the LED 100 may comprise only a single MEMS actuator that is ring-shaped surrounding the LED chip 101 such that the lens 104 can move in a linear direction whilst remaining in the same plane. Alternatively, the LED 100 may comprise a plurality of MEMS actuators, for example four MEMS actuators, all located below the lens 104 moving the lens 104 in a linear motion towards and/or away from the LED chip 101 when activated and deactivated. Each MEMS actuators may be configured to be controlled independently such that the lens is titled or angled. This is described in more detail below with reference to figures 4a, 4b and 5.

[0063] As a result of the MEMS actuators 103a, 103b being configured to move the lens 104 away from and/or towards the LED chip 101, with or without the assistance of the springs 105a, 105b, the light emitted by the LED can be controlled. In particular, the focal length of the lens 104 can be altered such that the light can be focused by moving the lens 104 further away from the LED chip and diffused by moving the lens 104 closer to the LED chip.

[0064] Another example of an LED 200 will now be described with reference to figures 2a and 2b.

[0065] In figures 2a and 2b, an LED 200 for controlling light emitted by an LED chip is illustrated, in particular for focusing and diffusing the light. It is similar to the LED 100 in that it comprises an optical element which is a flexible lens 204, an LED chip 201, and a first and a second MEMS actuator 203a, 203b and so a detailed description of the functionality of these components will be omitted, however it should be appreciated that the variations and alternatives described with reference to figures la and lb are also applicable to the LED 200 where appropriate.

[0066] The LED 200 differs from the LED 100 in that the first and second MEMS actuators 203a, 203b are located at opposing sides or ends of the lens such that when the MEMS actuators 203a, 203b are activated they apply a compressive force onto the lens 204 so that the lens is displaced or deformed, or in other words the curvature of the lens is increased which causes the light beam 202 to be diffused. That is, when the MEMS actuators 203a, 203b are deactivated (no electric current is supplied) they will not exert any force onto the lens 204 as illustrated in figure 2a. However, when the MEMS actuators 203a, 203b are activated (electric current is supplied) they will compress the lens 204 as the MEMS actuators 203a, 203b move parallel to the LED chip 201 towards the centre of the lens 204 as illustrated in figure 2b. Then, when the electric current supplied to the MEMS actuators 203a, 203b is stopped the MEMS actuators 203a, 203b are deactivated and revert to their original position as shown in figure la. As the MEMS actuators 203a, 203b return to their original position, the compressive forces exerted on the lens 204 are released and so also the lens 204 returns to its original shape.

[0067] Although figures 2a and 2b do not illustrate the LED 200 comprising springs similar to the LED 100 of figures la and lb, it should be appreciated that the LED 200 may comprise such springs. These springs would be located in parallel with the MEMS actuators 203a, 203b such that they would assist in pulling the MEMS actuators back to their original position.

[0068] It should be understood that springs in combination with MEMS actuators 203a, 203b may be used to apply compressive and also tensile forces to the lens 204 such that the lens 204 can compressed and its curvature increased relative to its original shape, and also stretched and its curvature flattened relative to its original shape.

[0069] In another example, the first and second MEMS actuators 203a, 203b would form a first set of MEMS actuators applying a compressive force on the lens 204 and the LED 200 would further comprise a second set of MEMS actuators would be configured to apply a tensile force on the lens 204 opposite to the direction of the compressive force such that the lens 204 would be able to be stretched and compressed relative to its original shape. In yet another example, the LED 200 only comprises the second set of MEMS actuators such that they are configured to apply tensile force only when the MEMS actuators are activated.

[0070] In yet another example, one of the MEMS actuators is replaced by an anchor such that only a single MEMS actuator is used to apply compressive and/or tensile forces to the lens 204.

[0071] By the MEMS actuators 203a, 203b being configured to distort, displace or deform the lens 204 by applying compressive and/or tensile forces in a direction parallel to the plane of the LED chip 201 (with or without the assistance of the springs) the light emitted by the LED chip 201 can be controlled. In particular, by the MEMS actuators 203a, 203b compressing the lens 204, the curvature of the lens is increased as seen in figure 2b which causes the light beam 202 to become more diffused. When the compressive forces are released and the lens returns to its original shape as shown in figure 2a, the curvature of the lens 204 is reduced and the light beam 202 becomes more focused.

[0072] Another example of an LED 300 will now be described with reference to figures 3a and 3b.

[0073] In figures 3a and 3b, an LED 300 for controlling light emitted by an LED chip is illustrated, in particular for focusing and diffusing the light. LED 300 is similar to the LED 200 in that it comprises an LED chip 301, an optical element 304 and a first and a second MEMS actuators 303a, 303b that are configured to displace the optical element 304 relative to the LED chip so as to control the light emitted by the LED chip. Therefore, a detailed description of the functionality of these components will be omitted, however it should be appreciated that the variations and alternatives described with reference to figures la to 2b b are also applicable to the LED 300 where appropriate.

[0074] The LED 300 differs to the LED 200 in that the optical element in this example is a flexible reflective component 304 such as a flexible mirror rather than a lens. The flexible reflective component 304 is located below the LED chip 301 rather than above the LED chip as for LED 200. Furthermore, the LED chip 301 is configured to emit light towards the reflective component 304 such that the reflective component reflects and collimates the light rays back in a direction towards the LED chip 301 as is illustrated by light beam 302 in figures 3a and 3b.

[0075] The first and second MEMS actuators 303a, 303b are configured similarly to the MEMS actuators 203a, 203b of LED 200 and so a detailed description will be omitted.

However briefly, when the MEMS actuators 303a, 303b are deactivated the reflective component 304 is curved with its concave surface facing the LED chip 301 such that it reflects the light beam 302 back in a direction towards the LED chip 301 as seen in figure 3a. When the MEMS actuators 303a, 303b are activated by electric current, they exert a compressive force on opposing ends or sides of the reflective component 304 such that the reflective component 304 is deformed or displaced relative to the LED chip 301 as seen in figure 3b. That is, the MEMS actuators 303a, 303b deform the reflective component 304 by compressing it such that its curvature increases. This results in the reflected light beam 302 being more focused.

[0076] Similar to the LEDs 100 and 200, it should be understood that the LED 300 can also comprise springs. These springs would be located in parallel with the MEMS actuators 303a, 303b such that they would assist in pulling the MEMS actuators back to their original position.

[0077] It should be understood that springs in combination with MEMS actuators 303a, 303b may be used to apply compressive and also tensile forces to the reflective component 304 such that it can be compressed and its curvature increased relative to its original shape, and also stretched and its curvature flattened relative to its original shape. In another example, another set of MEMS actuators are configured to apply a tensile force, instead of springs, to the reflective component. This other set of MEMS actuators would be located within the curvature of the reflective component 304. In this configuration, the first and second MEMS actuators 303a, 303b would form a first set of MEMS actuators exerting compressive force on the reflective component 304 and the other set of MEMS actuators would form a second set of MEMS actuators that would exert tensile force on the reflective component in the opposite direction to the first set of MEMS actuators 303a, 303b. This means that the reflective component 304 would be able to be stretched and compressed relative to its original shape. In yet another example, the LED 300 only comprises the second set of MEMS actuators located on the inside of the curvature of the reflective component 304 such that they are configured to apply a tensile force only when the MEMS actuators are activated.

[0078] In yet another example, one of the MEMS actuators is replaced by an anchor such that only a single MEMS actuator is used to apply compressive and/or tensile forces to the reflective component 304.

[0079] By the MEMS actuators 303a, 303b being configured to distort, displace or deform the reflective component 304 by applying compressive and/or tensile forces in a direction parallel to the LED chip 301, with or without the assistance of the springs, the light emitted by the LED chip 301 can be controlled. In particular, by the MEMS actuators 303a, 303b compressing the reflective component 304, its curvature is increased as seen in figure 3b which causes the light beam 302 to be focused. When the compressive forces are released and the reflective component 304 returns to its original shape as shown in figure 3a, the curvature of the lens 304 is reduced and the light beam 302 becomes more diffused.

[0080] Another example of an LED 400 will now be described with reference to figures 4a and 4b.

[0081] In figures 4a and 4b, an LED 400 for controlling light emitted by an LED chip is illustrated, in particular for controlling the direction of the light beam. The LED 400 is similar to LED 100 and so a detailed description will be omitted. However briefly, the LED 400 comprises an optical element which is a lens 404, an LED chip 401, a first and a second MEMS actuator 403a, 403b with associated springs 405a, 405b. The springs 405a, 405b may be optional. It should be appreciated that the variations and alternatives described with reference to figures la and lb are also applicable to the LED 400 where appropriate.

[0082] In this example, the MEMS actuators 403a, 403b may be configured such that the MEMS actuators are controlled separately meaning that they can displaces their end of the lens 402 independently of each other resulting in a tilting motion of the lens 402. That is, each MEMS actuator 405a, 405b can displace the lens 404 such that the lens 402 tilts. This results in the light beam 402 being angled or titled as seen in figure 4b such that the direction of the light beam 402 can be controlled. It is envisaged that the MEMS actuators are configured so that the light beam 402 can be continuously moved within the same plane such that it can be angled in a direction towards the first MEMS actuator 403a as seen in figure 4b, as well as towards the second MEMS actuator 403b. This may also be described as the MEMS actuators being configured so that the light beam can be rotated about a y-axis in a y' plane as shown in figure 4b.

[0083] It should be appreciated that the MEMS actuators 403a, 403b can also be configured to tilt the lens in combination with moving the lens away from and/or towards the LED chip 401, in other words along the z-axis. This enables the direction of the light beam to be controlled in combination with the focal length of the lens which affects the focus and diffusion of the light beam 402.

[0084] In another example, one of the MEMS actuators is replaced by an anchor such that the anchor fixes one end and only a single MEMS actuator is used to tilt the lens 404.

[0085] Although LED 400 has been described to comprise a first and a second MEMS actuator, it should be understood that it may also comprise a third and a fourth MEMS actuator. Each actuator can be positioned such that they engage the lens on the same side at an equidistance from one another.

[0086] In figure 5, an example of an LED 500 comprising four MEMS actuators is illustrated. This example is similar to LED 400 and so a detailed description will be omitted, however it should be appreciated that any alternatives and variations described with reference to LED 400 and LED 100 are also applicable to LED 500 where appropriate.

[0087] One difference between LED 500 and LED 400 is that the optical element of LED 500 comprises a lens 504 embedded or fixed to a supportive structure 510. Additionally, rather than two MEMS actuators, the LED 500 comprises four MEMS actuators; a first MEMS actuator 503a, a second MEMS actuator 503b, a third MEMS actuator 503c, and a fourth MEMS actuator 503d. Each MEMS actuator is configured to be controlled independently such that the lens 504 can be moved in a linear motion along a z-axis, in other words away from and/or towards the LED chip, as well as tilt or rotate about an x-axis and a y-axis, such that the light beam can move in planes x' and y'. Thus, this configuration allows for movement with 3 degrees of freedom, and it enables the light beam to be focused and diffused, and also for the direction of the light beam to be changed directed in also direction of the light beam can be controlled.

[0088] Another example of an LED 600 will now be described with reference to figures 6a and 6b.

[0089] In figures 6a and 6b, an LED 600 for controlling light emitted by an LED chip is illustrated, in particular for controlling the direction of the light beam. LED 600 is similar to the LED 300 in that it comprises an LED chip 601, an optical element of a flexible reflective component 604 such as a mirror and a first and a second MEMS actuators 603a, 603b that are configured to displace the reflective component 604 relative to the LED chip so as to control the light emitted by the LED chip. Therefore, a detailed description of the functionality of these components will be omitted, however it should be appreciated that the variations and alternatives described with reference to figures the previous examples are also applicable to the LED 600 where appropriate.

[0090] In this example, the LED 600 further comprises an anchor 611 which is attached to a central region of a convex surface of the reflective component 604 and to a corresponding part (not shown) of the LED 600. The anchor fixes the central region such that when the MEMS actuators 603a, 603b engage with the ends of the reflective component 604, the reflective component 604 is displaced or deformed by the MEMS actuators 603a, 603b resulting in that the angle of the light beam 602 is tilted or angled. That is, the central region of the reflective component is anchored such that its location is fixed regardless of the reflective component being stretched, compressed and/or tilted by the first and second MEMS actuators.

[0091] In particular, the MEMS actuators 603a, 603b are configured such that they are controlled separately meaning that they can displaces their end of the reflective component 604 independently of each other resulting in a tilting motion of the reflective component 604. That is, each MEMS actuator 603a, 603b can displace or deform the reflective component 604 such that the light beam 602 is tilted or angled as seen in figure 6b. It is envisaged that the MEMS actuators are configured so that the light beam 602 can be continuously moved within the same plane such that it can be angled in a direction towards the first MEMS actuator 603a as seen in figure 6b, as well as towards the second MEMS actuator 603b. This may also be described as the MEMS actuators being configured so that the light beam 602 can be rotated about a y-axis in a y' plane as shown in figure 6b.

[0092] It should be appreciated LED 600 may also be combined with the features of LED 300 such that compressive and tensile forces can be applied to the reflective component as well as the reflective component being tilted and/or moved away from the LED chip.

[0093] In one example, one of the MEMS actuators is replaced by an anchor such that the anchor fixes one end of the reflective component in position and only a single MEMS actuator is used to tilt the reflective component 604.

[0094] Although LED 600 has been described to comprise a first and a second MEMS actuator, it should be understood that it may also comprise a third and a fourth MEMS actuator. Each actuator can be positioned such that they engage the lens on the same side at an equidistance from one another. For example, the configuration of MEMS actuators described with reference to figure 5 can also be applied to the LED 600. In this example, the light beam 602 can be titled or angled as the MEMS actuators are engaging with the reflective component 604 such that the direction of the light beam can be controlled 602, as well as controlling focus and diffusion of the light beam by moving the reflective component towards and/or away from the LED chip.

[0095] Figure 7 illustrates an example of circuitries 700 of the LEDs described herein. The LED 400 with four MEMS actuators is shown in this figure as an example, however it should be understood that the circuitries 700 can be used with any of the LEDs described herein.

[0096] The circuitries 700 comprises a first circuitry 715 and a second circuitry 715. The LED chip 401 is operated by the first circuitry 715 and the MEMS actuators are operated by the second circuity 716. The first and second circuitries 715, 716 may be separate circuitries. Each circuitry is operated by a controller (not shown), the controller may be a single controller configured to operate both circuitries 715, 716 or it may comprise a plurality of controllers, for example, two controllers, one for each circuitry 715, 716. Each circuitry 715, 716 further comprises a BUS 717, 718, serial peripheral interface (SPI I/F) 720, 721, decoder unit 723, 724 and a pulse width modulator (PVVM) unit 725, 726. The BUS 717 is configured to transfer light data or light instructions from the controller to the LED chip 401, and the BUS 718 is configured to transfer MEMS data or MEMS instructions from the controller to the MEMS actuator(s) 403a, 403b, 43c, 403d. The light instructions and MEMS instructions correspond to input from a user an/or a computer program. To describe the transmission of the light instructions and the MEMS instructions in more detail, the light instructions and MEMS instructions are each sent from the controller to their corresponding SPI I/F 720, 721. The SPI I/F 720, 721 is a serial synchronous serial communication interface specification used for short-distance communication. It may be implemented on embedded microcontrollers forming part of the respective circuitry 715, 716, wherein the microcontrollers are configured to process light instructions and MEMS instructions received from the controller. The SPI/IF enable data to be sent to the PWM unit 725, 726 (via the decoder unit 723, 724) such that the data is easily translatable by the PVVM unit 75, 726 and so is already in common use for driving PVVM applications such as the LEDs.

[0097] The SPI/IF 720, 721 then send the light instructions and MEMS instructionsto their respective decoder unit 723, 724. The decoder units 723, 724 decode the instructions and then forward the instructions to the relevant PVVM unit 725, 726. The PVVM units 725, 726 are configured to control the electric current supplied to the LED chip and MEMS actuator(s). Thus, the PVVM 725 unit of the first circuity 705 enables the intensity of the LED emitters to be controlled. The PVVM unit 726 of the second circuitry 710 enables the degree of the mechanical output of the MEMS actuator(s) to be controlled. An advantage of having separate circuits 715, 716 for controlling the LED emitters and the MEMS actuators is that the intensity of the LED and the position and/or focus of the MEMS actuators can be controlled independently such that the refresh or update timings for the LEDs and MEMS actuators can be different. This can be particularly useful when the light of the LED will need to be updated or changed at a much higher frequency than the MEMS actuators.

[0098] Wien a single circuitry is used for controlling the light emitted by the LEDs and the MEMS actuators, the light instructions and the MEMS instructions can be interleaved in the same SPI I/F, however it would lead to increased complexity of the control system at the PVVM unit and also redundant data being transmitted should the refresh rate or update timings differ.

[0099] An example of an array of LEDs will now be described with reference to figures 8a and 8b.

[00100] Figures 8a and 8b illustrate an array 800 of LEDs for controlling the light output of the array. The array 800 of LEDs comprises any combination of the LEDs described herein. In the example shown in figures 8a and 8b the array 800 comprises five LEDs 719. However, it should be appreciated that the array is not limited to five LEDs but the array can comprise a much greater number of LEDs or fewer number of LEDs. Each of the MEMS actuator(s) for each LED may be controlled independently of one another such that the light beam of each LED can controlled independently. It should also be appreciated that some LEDs may be grouped such that that the MEMS actuators of the LEDs within a group may be controlled jointly but that the MEMS actuators of each group of LEDs are controlled independently.

[00101] In figure 8a, the direction of the light beam 720 of each LED 719 is controlled to be perpendicular to respective the LED, or more specifically to the LED chip. The focal length of the optical element of each LED is also controlled to be the same. This results in the light beam or light cone 720 to be the same of each LED 719 in the array 800.

[00102] In figure 8b, the light of the LEDs has been controlled and changed. The light beam of LEDs 719a, 719e have been diffused and the light beam of LEDs 719b, 719c, 719d have been focused. This has been achieved by the use of MEMS actuators as described herein. It should be understood that the direction of the light beam of each LED 719 can also be controlled in any of the ways described herein.

[00103] By arranging the LEDs into an array, the direction of the light can be controlled. This means that the light output of the array of LEDs can be grouped or aligned along a given path thereby increasing the intensity of the light output. Additionally, by aligning and controlling the light output, the light beam can be viewed "off angle" without chromatic differences in the colour and intensity of the light seen as would otherwise be experienced with array of LEDs where the light beams cannot be controlled.

[00104] An example of an LED display 900 will now be described with reference to figure 9.

[00105] In figure 9, a display 900 for controlling light emitted by LEDs 931 is illustrated.

The display 900 may be referred to as an LED display or display wall and it comprises arrays of LEDs 930 such as the array 800 described herein. The LED display may alternatively or in combination comprise discrete LEDs that are not formed in an array, these LEDs may be any of those described herein. Regardless of the configuration, each LED may be considered to correspond to a pixel. The light output of the display 900 can be manipulated by controlling the MEMS actuators as described herein for each LED 931.

The MEMS actuators of each LED 931 can be manipulated at high field rates which forms an effective volumetric field. By employing a spatial mapping which allows the correct mapping of complex imagery to arbitrary shaped surfaces, the assigned pixel value of each LED can be changed between one or more view/directional dependent images as the position of the light beam of each LED is changed. That is, each observer looking at the display 900 or within the display volume would see an image closest to the visually correct portion of the volumetric scene for their point of view. This allows the display 900 to be capable of showing several observers viewing the display from different angles visually correct images producing a volumetric effect. It also enables the screen to display different images for the right and left eyes of a single observer, also referred to as stereo separation, such that volumetric display is formed.

The array of LEDs and the display in accordance with the present disclosure have great applicability in the creative industry, in particular when used in mixed reality settings and virtual stage productions for music, video, film and theatre productions. For example, the light emitted by the LEDs can be cast onto nearby objects and actors, and the impact of the cast light can be controlled. That is, by diffusing the light emitted by the LEDs as described above, the impact the light has on a surface it is casting light onto can be softened, and by focusing the light, the light can be intensified as it is cast onto a surface. With regard to virtual stage production, the display and/or array of LEDs as disclosed herein can be used to cast light from a virtual scene displayed on the display and/or the array onto physical nearby objects, including actors and props, allowing the lighting impact to be controlled in terms of its intensity, in other words its hardness and softness. This provides a greater creative freedom and capability to reproduce hard to capture physical lighting effects.

Claims

CLAIMS1 A light-emitting diode, LED, comprising; an LED chip for emitting light, an optical element for collimating light rays of the emitted light, and a first microelectromechanical system, MEMS, actuator for displacing the optical element relative to the LED chip so as to control the light emitted by the LED chip.
2. An LED according to claim 1, wherein the MEMS actuator is configured to displace the optical element by any of, or a combination thereof; moving the optical element towards and/or away from the LED chip, tilting the optical element relative to the LED chip, and/or stretching and/or compressing the optical element in a direction parallel to the LED chip.
3. An LED according to claim 1, wherein the optical element is a lens and the LED further comprises a second MEMS actuator, the first and second MEMS actuators being configured to engage the lens at opposing ends so that the first and second MEMS actuators are operable to move the lens in a direction towards and/or away from the LED chip and/or tilt the lens relative to the LED chip.
4. An LED according to claim 1, wherein the optical element is a lens and the LED further comprises a second MEMS actuator, the first and the second MEMS actuators being configured to engage the lens at opposing ends so that the first and second MEMS actuators are operable to stretch and/or compress the lens in a direction parallel to the LED chip.
5. An LED according to claim 1, wherein the optical element is a flexible reflective component and the LED further comprises a second MEMS actuator, the first and the second MEMS actuators being configured to engage the reflective component at opposing ends so that the first and second MEMS actuators are operable to stretch and/or compress the reflective component in a direction parallel to the LED chip.
6. An LED according to claim 1, wherein the optical element is a flexible reflective component and the LED further comprises a second MEMS actuator, the first and the second MEMs actuators being configured to engage the reflective component at opposing ends so that the first and second MEMS actuators are operable to move the reflective component in a direction towards and away from the LED chip and/or tilt the flexible reflective component relative to the LED chip.
7. An LED according to any of claims 5 and 6, wherein a central region of the reflective component is anchored such that its location is fixed regardless of the reflective component being stretched, compressed and/or tilted by the first and second MEMS actuators.
8. An LED according to claims 3 or 6, further comprising a third a fourth MEMS actuator, wherein the first, second, third and fourth MEMS actuators are configured to engage the same surface of the lens at an equidistance therebetween, the MEMS actuators being operable to move the lens in a direction towards and/or away from the LED chip and/or tilt the lens relative to the LED chip
9. An LED according to any preceding claims, further comprising a spring associated with each MEMS actuator, the spring being configured to counteract the movement of its associated MEMS actuator.
10. An LED according to any preceding claim, wherein the LED chip is controlled by a first circuitry and the MEMS actuator(s) is controlled by a second circuitry.
11. An array of LEDs as claimed in any of the preceding claims.
12. An array of LEDs according to claim 10, wherein the MEMS actuator(s) for each LED is controlled independently of one another.
13. A display comprising a plurality of arrays as claimed in claims 11 and 12.
14. A display according to claim 13, wherein the arrays are controlled independently of one another.