Optical position sensing with temperature calibration

• US 10,054,763 B2
• Filed: 08/17/2015
• Issued: 08/21/2018
• Est. Priority Date: 08/17/2015
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Wong, Calvin K., Jeong, Ho Seop
• Primary Examiner(s): Tissire, Abdelaaziz
• Application Number:
  US14/828,434
• Publication Number:
  US 20170052343A1
• Time in Patent Office: 1,100 Days
• CPC Class Codes: G01B 11/026 by measuring distance between sensor and object G01B11/0608 takes precedence
• CPC Class Codes: G01D 5/26 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
• CPC Class Codes: G01M 11/08 Testing mechanical properties G01M11/005 takes precedence
• CPC Class Codes: G02B 7/028 with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation
• CPC Class Codes: G02B 7/08 adapted to co-operate with a remote control mechanism
• CPC Class Codes: G02B 7/28 Systems for automatic generation of focusing signals
• CPC Class Codes: H04N 23/67 Focus control based on electronic image sensor signals

Abstract

In some embodiments, an apparatus for performing temperature-compensated measurement of a position of a lens assembly is attached to an autofocus actuator. In some embodiments, the apparatus includes a light source for emitting light in a first direction. In some embodiments, a measurement sensor is affixed for receiving light reflected from a reflector. In some embodiments, a lateral shield is affixed in a position blocking detection by the measurement sensor of light having been emitted from light source but having not been reflected from the reflector. In some embodiments, a monitoring sensor is affixed in a position relative to the light source to receive light having been emitted from light source but having not been reflected from the reflector. In some embodiments, a transverse shield is affixed in a position blocking detection by the monitoring sensor of light reflected from the reflector.

Claims

1. An apparatus, comprising:

a reflector attached to a carrier of a lens assembly, wherein the carrier is coupled to an actuator to move the lens assembly together with the reflector along at least an optical axis of the lens assembly;

a light source for emitting light, wherein

the light comprises light emitted in a first direction that is a direction of a distance to be measured at least partly via a measurement sensor;

the measurement sensor, wherein

the measurement sensor is affixed in a position relative to the light source for receiving light emitted from the light source that has been reflected from the reflector;

a lateral shield that blocks detection by the measurement sensor of light emitted from the light source that has not been reflected from the reflector but that allows detection by the measurement sensor of light emitted from the light source that has been reflected from the reflector, wherein the lateral shield is affixed between the measurement sensor and the light source;

a monitoring sensor affixed in a position relative to the light source to receive light emitted from the light source that has not been reflected from the reflector; and

a transverse shield that blocks detection by the monitoring sensor of light emitted from the light source that has been reflected from the reflector but that allows detection by the monitoring sensor of light emitted from the light source that has not been reflected from the reflector.

2. The apparatus of claim 1, wherein the monitoring sensor comprises a monitoring photodetection diode.

3. The apparatus of claim 1, wherein the measurement sensor comprises a measurement photodetection diode.

4. The apparatus of claim 1, wherein the light source comprises a light-emitting diode.

5. The apparatus of claim 1, further comprising a driver circuit for supplying a current having a constant value to the light source.

6. The apparatus of claim 1, wherein the first direction is a direction towards the reflector.

7. The apparatus of claim 1, wherein the first direction is parallel to the optical axis.

8. A method, comprising:

emitting light from a light source, wherein

the light comprises light emitted in a first direction that is a direction of a distance to be measured at least partly via a measurement sensor;

generating a reflected light measurement by receiving at the measurement sensor light emitted from the light source that has been reflected from a reflector and that has not been blocked by a lateral shield that blocks detection by the measurement sensor of light emitted from the light source that has not been reflected from the reflector but allows detection by the measurement sensor of light emitted from the light source that has been reflected from the reflector;

generating an emitted light measurement by receiving at a monitoring sensor light emitted from the light source that has not been reflected from the reflector and that has not been blocked by a transverse shield that blocks detection by the monitoring sensor of light emitted from the light source that has been reflected from the reflector but allows detection by the monitoring sensor of light emitted from the light source that has not been reflected from the reflector; and

calculating a temperature dependent position measurement of the reflector based at least in part on the emitted light measurement and the reflected light measurement.

9. The method of claim 8, wherein:

the reflector is attached to a carrier of a lens assembly;

the carrier is coupled to an actuator for moving the lens assembly together with the reflector along at least an optical axis defined by the lens assembly; and

the method further comprises;

adjusting a position of the lens assembly, along the optical axis, based at least in part upon the temperature dependent position measurement.

10. The method of claim 8, wherein the generating the emitted light measurement further comprises measuring light received at a monitoring photodetection diode.

11. The method of claim 8, wherein generating the reflected light measurement comprises measuring light received at a measurement photodetection diode.

12. The method of claim 8, wherein the emitting light from the light source further comprises emitting light from a light-emitting diode.

13. The method of claim 8, further comprising a supplying a current having a constant value to the light source.

14. The method of claim 8, wherein the emitting light from the light source further comprises emitting light in a direction of the reflector attached to a carrier of a lens assembly.

15. The method of claim 9, wherein the first direction is parallel to the optical axis.

16. A non-transitory computer-readable storage medium storing program instructions, wherein the program instructions are computer-executable to implement:

controlling emission of light from a light source, wherein

the light comprises light emitted in a first direction that is a direction of a distance to be measured at least partly via a measurement sensor;

generating a reflected light measurement from an indication of receipt at the measurement sensor of light emitted from the light source that has been reflected from a reflector and that has not been blocked by a lateral shield that blocks detection by the measurement sensor of light emitted from the light source that has not been reflected from the reflector but allows detection by the measurement sensor of light emitted from the light source that has been reflected from the reflector;

generating an emitted light measurement from an indication of receipt at a monitoring sensor of light emitted from the light source that has not been reflected from the reflector and that has not been blocked by a transverse shield that blocks detection by the monitoring sensor of light emitted from the light source that has been reflected from the reflector but allows detection by the monitoring sensor of light emitted from the light source that has not been reflected from the reflector; and

calculating a temperature dependent position measurement of the reflector based at least in part on the emitted light measurement and the reflected light measurement.

17. The non-transitory computer-readable storage medium storing program instructions of claim 16, wherein:

the reflector is attached to a carrier of a lens assembly;

the carrier is coupled to an actuator to move the lens assembly together with the reflector along at least an optical axis defined by the lens assembly; and

the program instructions are further computer-executable to implement;

adjusting a position of the lens assembly based at least in part upon position measurement.

18. The non-transitory computer-readable storage medium storing program instructions of claim 16, wherein

the generating the emitted light measurement further comprises measuring light received at a monitoring photodetection diode.

19. The non-transitory computer-readable storage medium storing program instructions of claim 16, wherein

the program instructions computer-executable to implement generating a reflected light measurement comprise program instructions computer-executable to implement measuring light received at a measurement photodetection diode.

20. The non-transitory computer-readable storage medium storing program instructions of claim 16, wherein

the program instructions computer-executable to implement emitting light from the light source further comprise program instructions computer-executable to control emission of light from a light-emitting diode.