Auto-focus intra-oral camera having a linear piezoelectric actuator
View Patent ↗An auto-focus camera has an optical system for forming an image of a target, a moveable sensor for recording a set of one or more images of the target, the set of one or more images corresponding to a set of one or more positions for the moveable sensor, and a linear piezoelectric actuator mechanically coupled to the moveable sensor for driving the moveable sensor to the set of one or more positions along a predetermined moving direction in response to a stimulus. A driving system is actuable to generate the stimulus to drive the piezoelectric actuator. An image processor, in response to stored instructions, obtains the set of one or more recorded images from the moveable sensor, processes the set of one or more obtained recoded images, and identifies the image that is in focus.
1. An auto-focus camera comprising:
an optical system for forming an image of a target;
a moveable sensor for recording a set of one or more images of the target, the set of one or more images corresponding to a set of one or more positions for the moveable sensor;
a linear piezoelectric actuator that is mechanically coupled to the moveable sensor for driving the moveable sensor to the set of one or more positions along a predetermined moving direction in response to a stimulus;
a driving system actuable to generate the stimulus to drive the piezoelectric actuator; and
an image processor that, in response to stored instructions, obtains the set of one or more recorded images from the moveable sensor, processes the set of one or more obtained recorded images, and identifies the image that is in focus, wherein the linear piezoelectric actuator moves at an average speed of 50-100 mm/s along the predetermined moving direction.
2. The auto-focus camera of claim 1 , wherein the target is an intra-oral target.
3. The auto-focus camera of claim 1 , wherein the width of the camera along a direction that is perpendicular to the predetermined moving direction is not greater than 5 mm.
4. The auto-focus camera of claim 1 , wherein the piezoelectric actuator causes linear movement at an average step of 0.5-1.0 μm.
5. The auto-focus camera of claim 1 , wherein the driving system comprises an integrated circuit driver.
6. The auto-focus camera of claim 1 further comprising an illuminating system for directing light to the target.
7. The auto-focus camera of claim 1 , wherein the image that is in focus has the highest sharpness.
8. The auto-focus camera of claim 1 , wherein the linear piezoelectric actuator is connected to the moveable sensor through a wire.
9. The auto-focus camera of claim 1 , wherein forming the image is finished in not more than 0.2 second.
10. The auto-focus camera of claim 1 , wherein the image processor further sends one or more pulses to the driving system, the number of the pulses corresponding to different positions for the moveable sensor.
11. An auto-focus camera comprising:
an optical system for forming an image of a target;
a moveable sensor for recording the image of the target,
a linear piezoelectric actuator mechanically coupled to the moveable sensor for driving the moveable sensor along a predetermined moving direction in response to a stimulus;
a driving system actuable to provide the stimulus to drive the piezoelectric actuator to move the moveable sensor; and
an image processor that is connected to the driving system and the moveable sensor,
wherein the linear piezoelectric actuator moves at an average speed of between 50-100 mm/s along the predetermined moving direction and the processor responds to stored instructions to actuate the driving system to generate the stimulus that drives the piezoelectric actuator, which in turn moves the moveable sensor to a preferred position where the sensor records and stores the image of the target.
12. The auto-focus camera of claim 11 , wherein the target is an intra-oral target.
13. The auto-focus camera of claim 11 , wherein the width of the camera along a direction that is perpendicular to the predetermined moving direction is not greater than 5 mm.
14. The auto-focus camera of claim 11 , wherein the piezoelectric actuator causes linear movement at an average step of 0.5-1.0 μm.
15. The auto-focus camera of claim 11 , wherein the driving system comprises an integrated circuit driver.
16. The auto-focus camera of claim 11 further comprising an illuminating system for directing light to the target.
17. The auto-focus camera of claim 11 , wherein the image is a first image and wherein the sensor further records a second image and wherein the processor compares the first and second images for sharpness.
18. The auto-focus camera of claim 11 , wherein the linear piezoelectric actuator is connected to the moveable sensor through a wire.
19. The auto-focus camera of claim 11 , wherein forming the image is completed in not more than 0.2 second.
20. The auto-focus camera of claim 11 , wherein the image processor sends one or more pulses to the driving system, the number of the pulses corresponding to the position of the moveable sensor relative to the preferred position.