System and Method for controlling a camera shutter
View Patent ↗Systems and methods using the same to achieve a camera having precise timing of a camera shutter, which can be used also for a controllable aperture, are disclosed. The aperture can be controlled continuously and can therefore be used for video cameras. The shutter system is controlled by a feedback loop. The shutter blades are moved by at least one linear motor, a position sensor senses the actual position and speed of the blades. The movement of the blades can be stopped any time to get an aperture desired. For capturing an image in a first step a global reset is opening (activating) every pixel of the image sensor after the shutter is opened. In order to achieve a short active light exposure time (below 1 ms), after the global reset, the mechanical shutter invented closes rapidly after a defined active light exposure time. An active light exposure time is the time span between the image sensor is activated and the mechanical shutter is closed. In order to achieve a precise timing the shutter of the present invention uses electronic control and a feedback loop to control the actual position of the shutter.
1. A method to achieve a precise timing of a shutter of a digital camera, which can be used also for a continuously controllable aperture comprising the following steps:
(1) providing an image sensor and a lens barrel of a digital camera, one or more diaphragm shutter blades moved by at least one linear motor, wherein each linear motor comprises an iron core, a first coil wrapped around the iron core, a second coil wrapped around the iron core, and at least one magnet fastened on a device being connected to the one or more diaphragm shutter blades;
(2) setting up a continuously variable desired aperture opening by moving the shutter blades, wherein the actual position and speed of the one or more shutter blades is measured and controlled by a feedback loop;
(3) applying a global reset to said image sensor; and
(4) capturing an image and closing totally the one or more diaphragm shutter blades, wherein exposure time is a time span between said global reset and the totally closing of the shutter blades, wherein the actual position and speed of the one or more diaphragm shutter blades is measured and controlled by said feedback loop.
2. The method of claim 1 wherein the at least one linear motor further comprises two bidirectional linear motors for moving the shutter blades.
3. The method of claim 1 wherein the iron core of each of said at least one linear motor is fastened on a case of the camera shutter.
4. The method of claim 1 wherein sensors are measuring an actual position of said one or more diaphragm shutter blades.
5. The method of claim 4 wherein said sensors are capacitive sensors.
6. The method of claim 4 wherein said sensors are inductive sensors.
7. The method of claim 4 wherein said sensors are Hall sensors.
8. The method of claim 4 wherein sensors are measuring the speed of the shutter blades.
9. The method of claim 1 wherein a position of said one or more diaphragm shutter blades is controlled by the feedback loop.
10. The method of claim 1 wherein said magnets are fastened on a movable yoke, which is mechanically connected to the shutter blades.
11. The method of claim 1 wherein the one or more diaphragm shutter blades further comprise two diaphragm shutter blades.
12. The method of claim 1 wherein the aperture is controlled continuously.
13. The method of claim 1 wherein the one or more diaphragm shutter blades are used for a video camera, wherein the aperture is controlled continuously.
14. A camera having a precise timing of a camera shutter which can be used also for a continuously controllable aperture comprises:
an image sensor;
a movable lens barrel;
one or more actuators to move said lens barrel;
supports to guide the movements of the lens barrel;
a shutter case;
one or more diaphragm shutter blades, wherein each of the one or more diaphragm shutter blades is rotatably mounted on the shutter case and the one or more diaphragm shutter blades are moved by at least one linear motor, wherein the camera shutter combines a high speed shutter function and a continuously variable aperture;
said at least one linear motor to move said one or more diaphragm shutter blades, wherein the at least one linear motor comprises:
a first coil and a second coil wrapped around an iron core, wherein said iron core is fastened on said shutter case; and
at least one magnet, fastened on a device, which is mechanically connected to the one or more diaphragm shutter blades;
an integrated circuit controlling the motor driving the one or more diaphragm shutter blades and the actuators moving the lens barrel; and
at least one position sensor for directly, sensing a position of said one or more diaphragm shutter blades.
15. The camera module of claim 14 wherein said supports of the lens barrel are ball bearings.
16. A camera having a precise timing of its camera shutter which can be used also for a continuously controllable aperture comprises:
a shutter case;
one or more diaphragm shutter blades, wherein each of the one or more diaphragm shutter blades is rotatably mounted on the shutter case and the one or more diaphragm shutter blades are moved by at least one linear motor, wherein the camera shutter combines a high speed shutter function and a continuously variable aperture;
said at least one linear motor to move said one or more diaphragm shutter blades, wherein each motor comprises:
a first coil and a second coil wrapped around an iron core, wherein said iron core is fastened on said shutter case; and
at least one magnet, fastened on a device, which is mechanically connected to the shutter blades; and
at least one position sensor for directly, sensing a position of said one or more diaphragm shutter blades.
17. The camera of claim 16 wherein the one or more diaphragm shutter blades further comprises two diaphragm shutter blades.
18. The camera of claim 16 wherein said sensors are capacitive sensors.
19. The camera of claim 16 wherein said sensors are magnetic sensors.
20. The camera of claim 16 wherein said sensors are Hall sensors.
21. The camera of claim 16 wherein each linear motor has two coils.
22. The camera of claim 16 wherein each linear motor has two magnets.
23. The camera of claim 22 wherein said two magnets are contained in a metallic case.
24. The camera of claim 23 wherein said shutter case can be moved by shutter case linear motor.
25. The camera of claim 16 wherein said shutter case is supported for movement by ball bearings.
26. The camera of claim 16 wherein said movements of said one or more diaphragm shutter blades can be stopped any time in order to achieve an aperture of a desired size.
27. The camera of claim 16 wherein said shutter case is a movable shutter case adapted for slideable arrangement in direction of an optical axis of lens system of the camera.
28. The camera of claim 16 wherein said device, which is mechanically connected to the one or more diaphragm shutter blades is a yoke.
29. The camera of claim 16 wherein said aperture is controlled continuously.
30. The camera of claim 16 wherein said camera shutter is used for a video camera.