FIELD OF THE INVENTION

[0001] The present invention generally relates to imaging systems having an electrowetting lens.

SUMMARY OF THE INVENTION

[0002] According to one aspect of the present invention, an imaging system is provided comprising: an image sensor; an electrowetting lens positioned in front of the image sensor and configured to change at least one optical characteristic in response to an electrical stimulus so as to change a field of view of the image sensor; and a controller coupled to the electrowetting lens and configured to select a field of view of the image sensor by selecting the electrical stimulus to be applied to the electrowetting lens.

[0003] According to another embodiment of the present invention, an image sensor disposed in the vehicle is provided comprising: an image sensor disposed in the vehicle; an electrowetting lens positioned in front of the image sensor and configured to change at least one optical characteristic in response to an electrical stimulus so as to change a field of view of the image sensor; and a controller coupled to the electrowetting lens and configured to select a field of view of the image sensor by selecting the electrical stimulus to be applied to the electrowetting lens.

[0004] According to another embodiment of the present invention, an imaging system for scanning of a person's irises is provided comprising: an image sensor; an electrowetting lens positioned in front of the image sensor and configured to change at least one optical characteristic in response to an electrical stimulus so as to change a field of view of the image sensor; and a controller coupled to the electrowetting lens and configured to select a field of view of the image sensor by selecting the electrical stimulus to be applied to the electrowetting lens.

[0005] According to another embodiment of the present invention, an imaging system for scanning of a person's face for a facial recognition system is provided. The imaging system comprising: an image sensor; an electrowetting lens positioned in front of the image sensor and configured to change at least one optical characteristic in response to an electrical stimulus so as to change a field of view of the image sensor; and a controller coupled to the electrowetting lens and configured to select a field of view of the image sensor by selecting the electrical stimulus to be applied to the electrowetting lens.

[0006] These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.

BRI EF DESCRI PTION OF THE DRAWINGS

[0007] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein :

[0008] Fig. 1 is a block diagram showing an imaging system according to a first embodiment;

[0009] Fig. 2A is a block diagram illustrating use of an electrowetting lens to function with a narrower field of view;

[0010] Fig. 2B is a block diagram illustrating use of an electrowetting lens to function with a wider field of view;

[0011] Fig. 2C is a block diagram illustrating use of an electrowetting lens to function with a shifted field of view;

[0012] Fig. 3A is a top view of a vehicle having a plurality of imaging systems constructed in accordance with the embodiment shown in Fig. 1;

[0013] Fig. 3B is a top view of the vehicle shown in Fig. 3A with the fields of view of the cameras altered; and

[0014] Fig. 4 is a block diagram showing an imaging system according to a second embodiment.

DETAILED DESCRI PTION OF THE EMBODIMENTS

[0015] Fig. 1 shows an example of an imaging system 10 having an image sensor 20, an electrowetting lens 30 positioned in front of the image sensor 20 and configured to change at least one optical characteristic in response to an electrical stimulus so as to change a field of view of the image sensor 20, and a controller 40 coupled to the electrowetting lens 30 and configured to select a field of view of the image sensor 20 by selecting the electrical stimulus to be applied to the electrowetting lens 30. The electrowetting lens 30 may also be used for auto-focusing. [0016] The electrowetting lens 30 may take any form known in the art including the forms shown in Figs. 1 and 4. In general, as shown in Fig. 1, the electrowetting lens 30 includes an oil 32 that may take various shapes to form a variable lens in response to the application of an electrical stimulus such as the application of a selected voltage to one or more electrodes 34 within the electrowetting lens 30. The lens 30 may include two glass substrates 35a and 35b that combine with electrodes 34a, 34b and insulating member 36a to form a chamber in which the oil 32 is disposed. The remainder of the chamber in which the oil 32 is located is filled with another fluid such as water 33 that does not mix with the oil 32. Note that the electrode 34b that contacts the oil 32 may be coated with an insulator material. Figs. 2A, 2B, and 2C show three examples of the shapes the oil lens 32 may form in response to two different voltages applied to electrodes 34a and 34b. In Fig. 2A, the oil lens 32 takes the shape of a convex glass lens and the electrowetting lens 30 functions as a bi-convex lens. In Fig. 2B, the oil lens 32 takes the shape of a concave glass lens and the electrowetting lens 30 functions as a biconcave lens. In Fig. 2C, the oil lens 32 takes a tilted or rotated shape so that the electrowetting lens 30 shifts the field of view to one direction (i.e., left, right, up, or down). By changing the shape of oil lens 32, the focal length may be changed as may the direction of the optical axis. When placed in front of an image sensor 20, the electrowetting lens 30 may be used to change the field of view of the image sensor 20 as well as to pan the field of view across the imaging surface of the image sensor 20. Such a capability would provide many advantages in imaging systems used in vehicles as well as in security cameras and mobile devices, such as smartphones, notebooks, and laptop computers.

[0017] The electrowetting lens 30a shown in Fig. 4 is similar to that as shown in Fig. 1 except that the configuration of electrode 34b is different and rear glass substrate 35b includes a spherical recess with the electrode 34b coated over the entire surface of substrate 35b. An insulating layer 36b is provided across the entire surface of electrode 34b and fills the electrode-coated spherical recess in substrate 35b. Further, an annular glass ring 35c may be provided about the periphery of the chamber between substrates 35a and 35b. In this lens configuration, a drop of oil 32 is centered by a gradient in the electric field applied through electrodes 34a and 34b. [0018] One example of an application for imaging system 10 would be a rear vision camera 10a of a vehicle 18 as shown in Figs. 3A and 3B. In this application, the field of view 15a of the rear vision camera 10a could be dynamically changed without reducing the resolution of the image output from the rear vision camera 10a. For example, the field of view could be shifted to keep the image of any detected vehicle within the image. Further, the field of view could be widened or narrowed as shown in Figs. 3A and 3B depending upon whether the vehicle was in reverse or driving forward or depending upon the forward speed of the vehicle or the type of road upon which the vehicle is traveling. Note that the rear vision camera 10a may be located at the rear of the vehicle or at the sides of the vehicle as cameras 10a' and 10a" with respective variable fields of view 15a' and 15a". The images captured by the rear vision cameras 10a, 10a', and 10a" may be displayed on a display located in the rearview mirror 16 or other location in the instrument panel or console. Additionally or alternatively, the images may be processed for use in autonomous vehicle control or a driver assist function, such as parking assist, blind spot detection, rear collision warning, lane departure warning, lane keeping assist, etc.

[0019] Another example of a vehicle application for imaging system 10 would be as a forward vision camera 10b as shown in Fig. 3A. Such forward vision cameras 10b may be mounted at or near the rearview mirror 16 to capture images forward of the vehicle through its windshield. Images captured by the forward vision camera 10b may be used for a number of different driver assist functions or autonomous vehicle control functions. For example, the images may be used for headlamp control, lane departure warning, parking assist, adaptive cruise control, lane keeping assist, forward collision warning, object detection, pedestrian detection, and traffic sign recognition. However, it may be desirable to use a wider or narrower field of view 15b for each of these functions so as to limit the information in the captured images to that information that is relevant for the particular function. Accordingly, the provision of the electrowetting lens 30 in a forward vision camera 10b provides the advantage of changing the field of view for a selected function without a loss in resolution. Further, the ability of the electrowetting lens to shift the field of view 15b left or right allows the forward vision camera 10b to look in the direction of an upcoming turn. [0020] When used for headlamp control, the forward vision camera 10b may advantageously maintain a high pixel count per degree of field of view when the field of view is narrowed to focus on distant objects. This allows for more accurate detection of vehicles and other objects at greater distances. Likewise, the field of view may be changed to look ahead in the direction of an upcoming turn so that vehicles on the turn may be detected more quickly and accurately.

[0021] Another example of a vehicle application for imaging system 10 would be as an interior vision camera 10c as shown in Fig. 3A. Such interior vision cameras 10c may be mounted at or near the rearview mirror 16, an upper console, or reading light assembly in order to capture images inside the vehicle and display the images to the driver or other occupants. For example, such a camera 10c may be mounted to view back seat passengers and display the images to the driver on a display that may be mounted in the rearview mirror 16 or other location in the instrument panel or console. This is particularly useful if one of the passengers is a baby and even more advantageous if the baby is in a car seat facing rearward. By employing an electrowetting lens in such the interior vision camera 10c, the field of view 15c may be shifted around the interior of the vehicle so as to view a particular passenger or location in the vehicle. The field of view 15c may also be widened or narrowed to capture front seat passengers or focus on rear seat passengers. Such a change in the field of view 15c may be effectuated by manual control of the driver or automated control. Automated control may be used for video conferences so as to shift the field of view to whichever vehicle occupant is speaking.

[0022] By using the electrowetting lens 30 in imaging systems used in a vehicle, one can avoid having to only rely upon digital zooming for changing a field of view, which results in a reduction in the resolution of the images captured by the system. Further, to the extent one intends to avoid this by providing a mechanical zoom lens, such a mechanical zoom lens is much more complex to make and subject to breakage.

[0023] If the variable lens 30, 30a was oscillated between two or more images or fields of view, a first image stream having a first field of view could be supplied to a first display 50a and a second image stream having a different second field of view may be supplied to a second display 50b and thus two or more different image streams could be captured and displayed in real time. The different image streams could also be displayed in different display areas of one display 50a. Using one camera to collect multiple images is an advantage over using multiple cameras. For example, if the camera was set to oscillate between two images at 30Hz one could update two different images on two different displays or two different display zones at 15Hz.

[0024] The imaging system 10 may also find advantageous application in security cameras, particularly for those applications where two separate image sensors are used to capture retinal images of both a person's eyes. By using the electrowetting lens 30, the field of view may be shifted from one eye to the other and thereby eliminate the need for two separate cameras. Further, the field of view may be initially set to wide to capture a person's face and identify the location of their eyes and then zoom in on each eye. This would make it more practical to implement biometric screening security measures (particularly retinal imaging) in mobile devices, which typically only have one camera aimed in any one direction.

[0025] Security cameras having an electrowetting lens with a variable field of view may be used in home security systems as well as in smoke detectors and strobe light fixtures. Similarly, a vehicle camera such as camera 10c may be used for security purposes to scan the irises of the driver prior to starting the vehicle. The imaging system may also be used for scanning of a person's face for a facial recognition system.

[0026] Although imaging system 10 is shown as having just the electrowetting lens 30 in front of image sensor 20, additional conventional lenses may be used in combination with electrowetting lens 30 to obtain the desired fields of view and focus.The above description is considered that of the preferred embodiments only. Modifications of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the invention, which is defined by the claims as interpreted according to the principles of patent law, including the doctrine of equivalents.