OPTICAL DEVICE, METHOD FOR MANUFACTURING AN OPTICAL DEVICE AND METHOD FOR OPERATING AN OPTICAL DEVICE

Abstract

Described herein is an optical device comprising an optical element, which is mounted on a carrier by means of a platform, in which the platform comprises a base and an elastic structure, wherein the base is connected to the optical element, the elastic structure connects the base and the carrier, the platform extends along an x-y plane defined by an x-direction and a y-direction, an actuator is arranged to apply a force to the base in a direction along the x-y-plane, the elastic structure is elastic in the x-direction and in the y-direction, and the base and the elastic structure are fabricated in a one-piece manner

Claims

1. Optical device comprising an optical element, which is mounted on a carrier by means of a platform, the platform comprises a base and an elastic structure, wherein the base is connected to the optical element, the elastic structure connects the base and the carrier, the platform extends along an x-y plane defined by an x-direction and a y-direction, an actuator is arranged to apply a force to the base in a direction along the x-y-plane, the elastic structure is elastic in the x-direction and in the y-direction, and the optical element is a transmissive optical element.

2. Optical device according to claim 1 wherein the platform has a first resonance frequency along the x-direction and a second resonance frequency along the y-direction and the first and the second resonance frequencies are essentially identical, or the first and the second resonance frequency differ from each other between 1% and 5%.

3. Optical device according to claim 1, wherein the elastic structure comprises an x-spring and a y-spring, wherein the x-spring comprises at least one bending beam of a first kind and the y-spring comprises at least one bending beam of a second kind, wherein in an undeflected state the bending beam of the first kind extends perpendicularly to the x-direction, and in an undeflected state the bending beam of the second kind extends perpendicularly to the y-direction.

4. Optical device according to claim 3, wherein the base has an outer contour, the bending beam of the first kind extends along a first region of the outer contour, the bending beam of the second kind extends along a second region of the outer contour.

5. Optical device according to claim 1, wherein the stiffness of the elastic structure for movements in a direction obliquely with respect to the x-y-plane is at least 10 times higher than the stiffness of the elastic structure for movements in a direction along the x-y-plane.

6. Optical device according to claim 1 comprising a sensor which is arranged to detect a position of the base with respect to the carrier, and a controller which is arranged to control a frequency and/or amplitude of the relative motion of the base with respect to the carrier.

7. Optical device according to claim 6, wherein the actuator is a voice coil actuator, wherein the voice coil actuator is the sensor.

8. Optical device according to claim 1 comprising a transmission element, wherein the transmission element is arranged to limit the maximum deflection of the base with respect to the carrier in all directions along the x-y-plane, wherein the maximum deflection in all directions along the x-y-plane is essentially the same.

9. Optical device according to claim 1, wherein the base and the elastic structure are fabricated in a one-piece manner.

10. Optical device according to claim 1, comprising an optical axis extending through the optical element.

11. Method for manufacturing an optical device comprising a platform with a base and an elastic structure, wherein the base and the elastic structure are fabricated from a common metal sheet the base comprises a first portion of the metal sheet and the elastic structure comprises a second portion of the metal sheet, wherein the elastic structure is manufactured by bending the first portion by 90° with respect to the second portion.

12. Method according to claim 11, wherein the elastic structure comprises the x-spring with the bending beam of the first kind and the y-spring with the bending beam of the second kind, wherein the bending beam of the first kind and the bending beam of the second kind are fabricated in a one-piece manner

13. Method for driving an optical device comprising an optical element which is mounted on a carrier by means of a platform, wherein an actuator exerts a force to deflect the optical element with respect to the carrier, the actuator is driven with a periodic excitation signal having an excitation frequency, the platform has a first resonance frequency in an x-direction and a second resonance frequency in a y-direction, wherein either the excitation frequency is larger or smaller than both the first and the second resonance frequency, or the excitation frequency is in between the first and the second resonance frequency and the absolute value of the difference between excitation frequency and the first resonance frequency and the difference of the excitation frequency and the second frequency is essentially identical.

14. Method according to claim 13, wherein the optical device comprises a sensor which is arranged to detect a position of the base with respect to the carrier, and a controller which is arranged to control a frequency and/or amplitude of the relative motion of the base with respect to the carrier, wherein the movement path of the base in relation to the carrier is controlled with a position based closed-loop control circuit comprising the sensor and the controller.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0036] FIG. 1 shows an exemplary embodiment of an optical device in a schematic perspective view;

[0037] FIG. 2 shows an exemplary embodiment of an optical device in a schematic perspective view;

[0038] FIG. 3 shows an exemplary embodiment of an optical device in a schematic perspective view;

[0039] FIG. 4 shows in an exemplary embodiment a platform of an optical device in a schematic perspective view;

[0040] FIG. 5 shows an exemplary embodiment of an optical device with a transmission structure in a schematic perspective view;

[0041] FIG. 6 shows an exemplary embodiment of an optical device with a transmission structure in a schematic top view; and

[0042] FIG. 7 shows an exemplary embodiment of an optical device with a transmission structure in a schematic top view.

[0043] Identical, identical or identically acting elements are provided with the same reference symbols in the figures. The figures and the proportions of the elements shown in the figures among one another are not to be regarded as to scale. Rather, individual elements can be exaggerated in size for better displayability and/or for better comprehensibility.

DETAILED DESCRIPTION

[0044] FIG. 1 shows an exemplary embodiment of an optical device 1 in a schematic perspective view. The optical device 1 comprises an optical element 10, which is mounted on a carrier 20 by means of a platform 30. The optical element 10 is a diffusor. The platform 30 comprises a base 32 and an elastic structure 31. The base 32 is connected to the optical element 10 and the elastic structure 31 connects the base 32 and the carrier 20.

[0045] The elastic structure 31 comprises an x-spring and a y-spring. The x spring comprises at least one bending beam of a first kind 311 and the y-spring comprises at least one bending beam of a second kind 312. In an undeflected state the bending beam of the first kind 311 extends perpendicularly to the x-direction 101, and in an undeflected state the bending beam of the second kind 312 extends perpendicularly to the y-direction 102. The platform 30 has a first resonance frequency along the x-direction 101 and a second resonance frequency along the y-direction 102 and the first and the second resonance frequencies are essentially identical, or the first and the second resonance frequency differ from each other between 1% and 5%. The first resonance frequency essentially depends on the elasticity of the x-spring and the mass of the base 32 and the optical element 10. The second resonance frequency essentially depends on the elasticity of the y-spring and the mass of the base 32 and the optical element 10.

[0046] The platform 30 extends along an x-y plane defined by an x-direction 101 and a y-direction 102. The elastic structure 31 is elastic in the x-direction 101 and in the y-direction 102. The stiffness of the elastic structure 32 for movements in a direction obliquely, in particular perpendicularly, with respect to the x-y-plane is at least 10 time higher than the stiffness of the elastic structure 32 for movements in a direction along the x-y-plane.

[0047] An actuator 40 is arranged to apply a force to the base 32 in a direction along the x-y-plane. The actuator 40 comprises multiple voice coil actuators, wherein the coils are integrated in the carrier 20. In particular, the carrier 20 is a PCB and the conductive tracks of the PCB form a coil which is integrated in the PCB. Furthermore, the actuator 40 comprises multiple magnets (not shown in the figure) which are attached to the base 32. The voice coil actuators are used as a sensor 51 to detect a position of the base 32 with respect to the carrier 20. A controller 50 is arranged to control a frequency and/or amplitude of the relative motion of the base 32 with respect to the carrier 20.

[0048] The base 32 and the elastic structure 31 are fabricated in a one-piece manner from a common metal sheet. The base 32 comprises a first portion of the metal sheet and the elastic structure 31 comprises a second portion of the metal sheet. The elastic structure 31 is manufactured by bending the first portion by 90° with respect to the second portion. Thus, the elastic structure 31 extends perpendicularly with respect to the xy-plane.

[0049] The elastic structure comprises the x-spring with two bending beams of the first kind 311 and the y-spring with two bending beams of the second kind 312. Each bending beam of the first kind 311 is mechanically connected to one of the bending beams of the second kind 312. Each bending beam of a first kind 311 is fabricated in a one-piece manner with a bending beam of a second kind 312. In operation the actuator 40 is driven with a periodic excitation signal having an excitation frequency. Either the excitation frequency is larger or smaller than both the first and the second resonance frequency, or the excitation frequency is in between the first and the second resonance frequency and the absolute value of the difference between excitation frequency and the first resonance frequency and the difference of the excitation frequency and the second frequency is essentially identical. In operation, the actuator 40 is driven, such that the base 32 performs an elliptic, preferably circular, motion along the xy-plane with respect to the carrier 20. In particular, the controller 50 enables a closed loop control. In particular, the controller has two channels, wherein a first channel is arranged to control a force of the actuator 40 along the x-direction 101 and a second channel is arranged to control a force of the actuator 40 along the y-direction 102. The frequency of said motion is preferably between 30 Hz and 200 Hz, highly preferred between 50 Hz and 80 Hz. The peak to peak amplitude of said motion is in a range of 0.5 mm to 5 mm, while the amplitude of the motion in a direction perpendicular to the xy-plane is below 0.1 mm

[0050] FIG. 2 shows an exemplary embodiment of an optical device 1 in a schematic perspective view. The optical device 1 shown in FIG. 2 differs from the embodiment shown in FIG. 1 in the design of the elastic structure. The embodiment in FIG. 2 comprises an x-spring having four bending beams of the first kind 311 and a y-spring with four bending beams of the second kind 312.

[0051] FIG. 3 shows an exemplary embodiment of an optical device 1 in a schematic perspective view. The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 2 in the attachment of the optical element 10 to the base 32. The optical element 10 is attached to the base 32 by means of a fixing element 34. The fixing element 34 is a clamp, which attaches the optical element 10 to the base 32 by means of a non-positive connection.

[0052] FIG. 4 shows in an exemplary embodiment a platform 30 of an optical device 1 in a schematic perspective view. The platform comprises the base 32. In the base 32 is a recess, which is transparent for light in the visible wavelength range.

[0053] FIG. 5 shows an exemplary embodiment of an optical device 1 with a transmission structure 60 in a schematic perspective view. The transmission structure 60 comprises four openings 62 which are arranged in the base 32 and four pins 61. Both, openings 62 and pins 61 have a circular contour seen in top view. Each pin 61 extends through one of the openings 62. The pins 61 have a smaller diameter than the openings 62. The ratio of the diameter of the opening to the diameter of the pin defines the amplitude of the motion path of the base 32. The transmission structure limits the maximum deflection of the base 32 with respect to the carrier 20 along the xy-plane. In operation, the pin lies against the inner contour limiting the opening 62. Thereby the contour of the opening 62 defines the movement path of the base 32.

[0054] FIG. 6 shows an exemplary embodiment of an optical device with a transmission structure 60 in a schematic top view. The x-spring and the y-spring are designed such that the first resonance frequency and the second resonance frequency are below 10 Hz. Thus, essentially the transmission structure 60 directs the motion of the base 32.

[0055] FIG. 7 shows an exemplary embodiment of an optical device 1 with a transmission structure 60 in a schematic top view. The transmission structure 60 shown in FIG. 7 differs from the embodiment of the transmission structure shown in FIG. 6. The transmission structure 60 is a cam 65 having an axis 63 and a bearing 64. The axis 63 is the axis of rotation around which the bearing 64 rotates during intended operation. The axis 63 is off center of the bearing 64. Thus, the base is forced into a circular motion with respect to the carrier 20. The distance of the axis 63 to the bearing 64 respectively defines the amplitude of the circular motion path of the base 32.

[0056] The invention is not restricted to the exemplary embodiments by the description based on these. Rather, the invention encompasses every new feature and every combination of features, which in particular includes every combination of features in the patent claims, even if this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.

LIST OF REFERENCE NUMERALS

[0057] 1 Optical device

[0058] 20 Carrier

[0059] 30 Platform

[0060] 31 Elastic structure

[0061] 311 Beam of first kind

[0062] 312 Beam of second kind

[0063] 32 Base

[0064] 33 Recess

[0065] 34 Fixing element

[0066] 40 Actuator

[0067] 50 Controller

[0068] 51 Sensor

[0069] 60 Transmission structure

[0070] 61 Pin

[0071] 62 Opening

[0072] 63 Axis

[0073] 64 Bearing

[0074] 65 Cam

[0075] 101 x-direction

[0076] 102 y-direction