Patent Description:
Known camera assembly techniques have another drawback in addition to the added expense associated with the specialized equipment and time delays mentioned above. Once the camera sensor and lens are cured in position, future adjustment or calibration is not possible. Given the wide range of environmental conditions vehicles and their components are exposed to over time, camera devices are subject to material creep, printed circuit board warping, stresses from mechanical shock and vibration, and deterioration of the adhesive that secures the lens and sensor in the calibrated position. It is not possible to adjust or recalibrate the camera over time, which introduces additional expenses if a camera is replaced. If not replaced, the camera simply remains in a less-than-ideal calibration state.

<CIT> discloses a camera system comprising the features according to the preamble of claim <NUM>.

<CIT> discloses a camera system comprising features according to a related technology.

<CIT> also discloses a camera system comprising features according to a related technology.

<CIT> discloses an electronic device including an image sensor, optics, a detector for detecting a movement and an optical image stabilizer configured to actuate at least part of the optics in order to compensate the detected movement.

It is an object of the invention to provide a camera device and a corresponding method which allow for regular recalibrations during the service life of the camera device.

This object is satisfied by a camera system comprising the features of claim <NUM> and a method comprising the features of claim <NUM>. The camera device includes a substrate and a sensor supported on the substrate. The sensor is configured to gather image information. A lens is situated near the sensor and an electroactive polymer selectively causes relative movement between the sensor and the lens.

Moreover, the camera device includes a housing supporting the lens and the substrate. The electroactive polymer is situated between the substrate and a reaction surface of the housing, a space occupied by the electroactive polymer changes responsive to electrical energy, the electroactive polymer reacts against the reaction surface as the space occupied by electroactive polymer changes, and a position of the substrate relative to the housing changes as the electroactive polymer reacts against the reaction surface.

In addition, the camera device includes at least one resilient member associated with the substrate for allowing relative movement between the substrate and the reaction surface as the electroactive polymer reacts against the reaction surface.

An example embodiment having one or more features of the camera device includes a controller that is configured to control electrical energy applied to the electroactive polymer in an amount that causes the relative movement between the sensor and the lens.

In an example embodiment having one or more features of the camera device of any of the previous paragraphs, the controller is configured to determine when the camera device is in a calibrated state, determine at least one characteristic of the electrical energy applied to the electroactive polymer when the camera device is in the calibrated state, and maintain the at least one characteristic of the electrical energy to maintain the calibrated state of the camera device.

In an example embodiment having one or more features of the camera device of any of the previous paragraphs, the controller is configured to selectively adjust a position of at least one of the sensor or lens relative to the other of the lens or sensor to recalibrate the camera device.

In an example embodiment having one or more features of the camera device of any of the previous paragraphs, the electroactive polymer is situated against the substrate and the substrate includes at least one conductive trace for providing electrical energy to the electroactive polymer.

In an example embodiment having one or more features of the camera device of any of the previous paragraphs, the at least one resilient member biases the substrate toward the reaction surface.

In an example embodiment having one or more features of the camera device of any of the previous paragraphs, the electroactive polymer comprises a plurality of portions supported on the substrate and the at least one resilient member comprises a plurality of members respectively associated with the portions of the electroactive polymer.

In an example embodiment having one or more features of the camera device of any of the previous paragraphs, the housing includes a substrate support, at least one fastener is received through an opening in the substrate support, the at least one fastener is secured to the housing, and the at least one resilient member is associated with the at least one fastener and situated to allow relative movement between the substrate support and the reaction surface.

In an example embodiment having one or more features of the camera device of any of the previous paragraphs, the lens is supported in a fixed position relative to the housing.

In an example embodiment having one or more features of the camera device of any of the previous paragraphs, the relative movement includes at least one of a change in a distance between the sensor and the lens and a change in an angle of tilt between the sensor and the lens.

In an example embodiment having one or more features of the camera device of any of the previous paragraphs, the electroactive polymer comprises a plurality of portions supported on the substrate in respective locations, each of the portions responds to an amount of electrical energy applied to it, and different amounts of electrical energy applied to the portions, respectively, causes different relative movements between the sensor and the lens.

The method of calibrating a camera device includes providing electrical energy to an electroactive polymer to cause relative movement between a sensor and a lens of the camera device to achieve a first relative orientation between the sensor and the lens, obtaining a first camera image of a reference when the sensor and the lens are in the first relative orientation, determining whether a correspondence between the first camera image and the reference indicates that the camera device is calibrated.

In an example embodiment having one or more features of the method of the previous paragraph, the correspondence between the first camera image and the reference indicates that the camera device is not calibrated and the method includes providing a different amount of electrical energy to the electroactive polymer to cause relative movement between the sensor and the lens to achieve a second, different relative orientation between the sensor and the lens, obtaining a second camera image of a reference when the sensor and the lens are in the second relative orientation, and determining whether a correspondence between the second camera image and the reference indicates that the camera device is calibrated.

In an example embodiment having one or more features of the method of any of the previous paragraphs, the electroactive polymer comprises a plurality of portions and providing the electrical energy comprises providing electrical energy having a first characteristic to a first one of the portions and providing electrical energy having a second, different characteristic to a second one of the portions.

In an example embodiment having one or more features of the method of any of the previous paragraphs, the relative movement between the sensor and the lens changes at least one of a distance between the sensor and the lens and an angle of the sensor relative to the lens.

In an example embodiment having one or more features of the method of any of the previous paragraphs, the camera device is supported on a vehicle and the method comprises performing the providing, obtaining and determining a plurality of times during a service life of the camera device.

An illustrative example camera device includes a substrate, sensor means supported on the substrate for gathering image information, a lens near the sensor, an electroactive polymer that selectively causes relative movement between the sensor and the lens, and control means for controlling electrical energy applied to the electroactive polymer in an amount that causes the relative movement between the sensor and the lens.

In an example embodiment having one or more features of the camera device of the previous paragraph, the control means is configured to selectively adjust a position of at least one of the sensor or lens relative to the other of the lens or sensor for recalibrating the camera device.

<FIG> schematically illustrates camera devices <NUM> supported on a vehicle <NUM>. The camera devices <NUM> may be used for a variety of detection or image gathering purposes, such as detecting objects or conditions in a vicinity of the vehicle.

As shown in <FIG>, the cameras <NUM> each include a housing <NUM> that supports a lens <NUM>. A sensor <NUM> that is configured to capture images or gather image information is supported on a substrate <NUM>. In the illustrated example embodiment, the substrate <NUM> is a generally planar printed circuit board. The sensor <NUM> is secured in a fixed position on the substrate <NUM>, which is accomplished by soldering the sensor <NUM> in place in some embodiments.

An electroactive polymer <NUM> responds to electrical energy by changing shape or volume. The electroactive polymer <NUM> selectively causes relative movement between the sensor <NUM> and the lens <NUM> as it responds to changes in electrical energy provided to it. Such relative movement is useful for focusing or calibrating the camera <NUM>. One feature of the illustrated example embodiment is that the electroactive polymer facilitates camera calibration during a manufacturing process and subsequently as may be needed during the service life of the camera <NUM>. This feature is different from many camera devices in which the lens and sensor are set in manner that does not allow subsequent adjustment once the device is made.

In the illustrated example embodiment, the electroactive polymer <NUM> includes a plurality of portions or pads situated on the substrate <NUM>. The portions of the electroactive polymer <NUM> are situated between the substrate <NUM> and a reaction surface <NUM> on the housing <NUM>. The substrate <NUM> is supported in the housing by a substrate support <NUM>. A plurality of fasteners <NUM>, such as screws, hold the substrate support <NUM> in a desired location within the housing <NUM>. Resilient members <NUM> are associated with the fasteners <NUM> and the substrate support <NUM> to allow for some movement of the substrate <NUM> within the housing. The resilient members <NUM> comprise springs in some embodiments and compressive pads in other embodiments. The resilient members <NUM> bias the substrate <NUM> and the portions of electroactive polymer <NUM> toward the reaction surface <NUM>.

As shown in <FIG>, the camera <NUM> includes a controller <NUM> that selectively provides electrical energy to the portions of electroactive polymer <NUM>. In this example, circuit traces <NUM> on the substrate <NUM> conduct the desired amount of electrical energy to the portions of the electroactive polymer <NUM>.

The controller <NUM> includes a processor or another computing device and memory. The controller <NUM> selectively provides electrical energy to the portions of electroactive polymer <NUM>, respectively, to achieve a desired orientation between the lens <NUM> and the sensor <NUM>. By changing the amount of electrical energy provided to each portion of electroactive polymer, the controller <NUM> is able to cause relative movement between the sensor <NUM> and the lens in three dimensions. For example, individually causing the portions of electroactive polymer <NUM> to expand or contract as schematically shown by the arrows <NUM> changes the position of the corresponding portion of the substrate <NUM> relative to the reaction surface <NUM> of the housing <NUM>. The sensor <NUM> moves with the substrate <NUM> and therefore the distance between the lens <NUM> and the sensor <NUM> is adjustable as schematically shown by the arrows <NUM> in <FIG>. Additionally, the controller <NUM> can control the electrical energy provided to the pads or portions of electroactive polymer <NUM> to selectively adjust a tilt angle of the sensor <NUM> as schematically shown by the adjustment arrow <NUM>.

Causing relative movement between the lens <NUM> and the sensor <NUM> facilitates calibrating the camera <NUM>. An example calibration technique is summarized in the flow chart <NUM> of <FIG>. Calibration begins at <NUM>. At <NUM>, the sensor <NUM> obtains an image of a reference, such as a known pattern or series of visible images. The controller <NUM> determines whether the image obtained by the sensor <NUM> corresponds to the reference at <NUM>. If there is insufficient correspondence between the captured image information and the reference, the controller changes the electrical energy provided to at least one of the portions of electroactive polymer <NUM> at <NUM>. The sensor obtains another image at <NUM> and the controller compares the most recently obtained image with the reference at <NUM>. This process continues until there is sufficient correspondence between the captured image and the reference to indicate that the camera is properly calibrated. Once calibrated, at <NUM>, the controller <NUM> stores at least one characteristic of the electrical energy provided to the respective portions of electroactive polymer <NUM>. Example stored characteristics include voltage and current. The stored characteristics are subsequently used by the controller <NUM> to place or keep the sensor <NUM> and the lens <NUM> properly aligned to maintain calibration of the camera <NUM>.

One feature of the illustrated embodiment is that it is possible to perform such calibration during a manufacturing process and subsequently at various times during the service life of the camera <NUM>. For example, when the camera <NUM> is supported on the vehicle <NUM> it is possible for temperature conditions or impact to adversely affect the components of the camera <NUM> causing the camera <NUM> to lose calibration or to operate in a less-than-ideal manner. When a suitable reference is available, such as at a vehicle service center, the controller <NUM> can execute the calibration process summarized above to recalibrate the camera <NUM>. Previous camera configurations without the electroactive polymer <NUM> could not be recalibrated because the lens <NUM> and sensor <NUM> are fixed in a manner that does not allow subsequent adjustment.

There are known electroactive polymer materials and those skilled in the art who have the benefit of this description will be able to select an appropriate material for their particular situation. An electroactive polymer is considered advantageous over a piezoelectric material, for example, because electroactive polymers have better strain percentage properties allowing for more adjustment or relative movement between the lens <NUM> and the sensor <NUM>.

Although the sensor <NUM> and substrate <NUM> are moveable relative to the housing <NUM> while the lens remains stationary relative to the housing <NUM> in the illustrated example embodiment, other embodiments include a moveable lens <NUM>.

Claim 1:
A camera device (<NUM>), comprising:
a substrate (<NUM>);
a sensor means (<NUM>) supported on a first side of the substrate (<NUM>), the sensor means (<NUM>) being configured to gather image information;
a lens (<NUM>) near the sensor means (<NUM>);
a housing (<NUM>) supporting the lens (<NUM>) and the substrate (<NUM>);
an electroactive polymer (<NUM>) used to recalibrate the camera device, a space occupied by the electroactive polymer (<NUM>) changing responsive to electrical energy, the electroactive polymer configured to selectively cause relative movement between the sensor means (<NUM>) and the lens (<NUM>), the electroactive polymer comprising a plurality of electroactive polymer pads situated on the first side of the substrate (<NUM>) in respective locations between the substrate (<NUM>) and a reaction surface (<NUM>) of the housing (<NUM>), the electroactive polymer (<NUM>) further configured to react against the reaction surface (<NUM>) as the space occupied by the electroactive polymer (<NUM>) changes, and a position of the substrate (<NUM>) relative to the housing (<NUM>) changing as the electroactive polymer (<NUM>) reacts against the reaction surface (<NUM>),
characterized by
at least one resilient member (<NUM>) associated with the substrate (<NUM>) for allowing relative movement between the substrate (<NUM>) and the reaction surface (<NUM>) as the electroactive polymer (<NUM>) reacts against the reaction surface (<NUM>).