Shutter actuation

An imaging device includes a frame. An imaging sensor is seated in the frame. A shutter is pivotally mounted to the frame along a pivot axis. The shutter is positioned to pivot between a first position that is clear of the imaging sensor and a second position that occludes the imaging sensor. A linear actuator is pivotally connected to the shutter at a linkage axis that is offset from the pivot axis for actuating the shutter between the first and second positions.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to imaging systems, and more particularly to shutter actuation for imaging systems.

2. Description of Related Art

Imaging systems such as cameras utilize shutters to cover over the imaging sensor. In infrared imaging systems, calibration shutters are used to recalibrate the imaging sensor. In this context, a shutter covers the sensor and the sensor images the shutter. The shutter can be temperature controlled, or a sensor can be used to determine the temperature of the shutter. Using the known temperature of the calibration shutter allows the system to recalibrate the imaging sensor. If this is done periodically, the imaging sensor can stay well calibrated. One drawback to shutter actuation is that the shutter can generate audible noise as it is actuated. In sound sensitive applications, the actuation noise of a calibration shutter can be a disadvantage.

The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved shutter calibration. This disclosure provides a solution for this need.

SUMMARY OF THE INVENTION

An imaging device includes a frame. An imaging sensor is seated in the frame. A shutter is pivotally mounted to the frame along a pivot axis. The shutter is positioned to pivot between a first position that is clear of the imaging sensor and a second position that occludes the imaging sensor. A linear actuator is pivotally connected to the shutter at a linkage axis that is offset from the pivot axis for actuating the shutter between the first and second positions.

The imaging sensor can be aligned normal to an optical axis that is parallel to the pivot axis. The shutter can pivotally connect to the frame through a bearing. The linear actuator can include a rotary motor that is spaced apart from a flag portion of the shutter through at least one link of a linkage.

The linear actuator can include a rotary motor mounted to the frame. The rotary motor can be operatively connected to a lead screw threaded to a nut that is mounted a fixed distance from the linkage axis. The rotary motor can be a stepper motor. The rotary motor can be pivotally mounted to an arm along a mounting axis offset from the pivot axis and the linkage axis. The arm can be mounted in a fixed position relative to the frame. The rotary motor can include a rotating shaft coupled to the lead screw. The shaft and the lead screw can be configured to rotate about a drive axis that is angled orthogonal to and is offset from the pivot axis. The nut can be an anti-backlash nut configured to maintain at least one of a state of tension or compression relative to the lead screw. The nut can be mounted in a link that is pivotally mounted to the shutter at the linkage axis. The shutter can include a flag portion configured to occlude the imaging sensor. The link can connect to a leg of the shutter between the flag portion and the pivot axis.

A method of shutter actuation includes actuating a shutter including a flag portion configured to occlude an imaging sensor, wherein a rotary motor drives actuation of the shutter. The method includes attenuating sound between the rotary motor to the flag portion through a linear actuator linkage. Actuating can include rotating the shutter about a pivot axis by rotating the rotary motor about a drive axis that is orthogonal to and is offset from the pivot axis.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of an imaging device in accordance with the disclosure is shown inFIG. 1and is designated generally by reference character100. Other embodiments of imaging devices in accordance with the disclosure, or aspects thereof, are provided inFIG. 2, as will be described. The systems and methods described herein can be used for shutter actuation, e.g., for calibration shutters in infrared imaging devices such as infrared goggles.

The imaging device100includes a frame102. An imaging sensor104is seated in the frame102. A shutter106is pivotally mounted to the frame102by a bearing108, e.g., a simple bearing using polytetrafluoroethylene (PTFE), that rotates along a pivot axis P. The shutter106is positioned to pivot between a first position that is clear of the imaging sensor104, shown in solid lines inFIG. 1, and a second position (schematically indicated inFIG. 1with broken lines) that occludes the imaging sensor104, e.g., for calibrating the imaging sensor using a known temperature of the flag portion114. A linear actuator110is pivotally connected to the shutter106at a linkage axis L that is offset from the pivot axis P for actuating the shutter106between the first and second positions. The imaging sensor104is aligned normal to an optical axis O, labeled inFIG. 2, that is parallel to the pivot axis P.

The linear actuator110includes a rotary motor112that is spaced apart from a flag portion114of the shutter106through a linkage that includes a lead screw116and a link118. The link118pivotally connects to a leg120of the shutter106at the linkage axis L that is between the flag portion114and the pivot axis P, however those skilled in the art will readily appreciate that the link118can connect to a projection off of the leg120on the other side of the pivot axis P.

The rotary motor112is pivotally mounted to an arm122along a mounting axis M that is offset from the pivot axis P and the linkage axis L. The arm122is mounted in a fixed position relative to the frame102. The rotary motor112can be a stepper motor that can be controlled to drive its shaft124clockwise and counterclockwise. The rotating shaft124of the rotary motor112is operatively connected by a shaft coupling126to the lead screw116. The lead screw116is threaded to a nut128that is mounted a fixed distance from the linkage axis L, i.e., the nut128is mounted fixed in place within the link118, i.e., to prevent the nut128from spinning when the lead screw116spins. The shaft124and the lead screw116are configured to rotate about a drive axis D that is angled orthogonal to the pivot axis P (as can be seen inFIG. 2) to and is offset from the pivot axis P (as can be seen inFIG. 1). Due to the threading engagement of the nut128and the lead screw116, rotating the rotary motor112one way (clockwise or counterclockwise) shortens the linkage distance between the axes L and M and moves the flag portion114from the first position to the second position, and rotating the rotary motor112the other direction (clockwise or counterclockwise) lengthens the linkage distance between axes L and M and moves the flag portion114from the second position to the first position. The nut128is an anti-backlash nut configured to maintain at least one of a state of tension or compression relative to the lead screw116so there is little or no play between the lead screw116and the nut128for reduction of vibrations and audible noise from the linear actuator110.

A method of shutter actuation includes actuating a shutter (e.g. shutter106), including a flag portion (e.g., flag portion114) configured to occlude an imaging sensor (e.g., imaging sensor104), wherein a rotary motor (e.g., rotary motor112) drives actuation of the shutter. The method includes attenuating sound between the rotary motor to the flag portion through a linear actuator linkage (e.g., the linkage of actuator110). Actuating includes rotating the shutter about a pivot axis (e.g., pivot axis P) by rotating the rotary motor about a drive axis (e.g., drive axis D) that is orthogonal to and is offset from the pivot axis.

Potential benefits using systems and methods disclosed herein relative to traditional systems and techniques include less vibration created from the shutter drive system, reduced vibration migrating out beyond the shutter (which can prevent resonating, e.g., in a goggle case), without backlash the flag position is controlled more accurately, reduced cost, and PTFE bearings in the pivoting joints can further attenuate audible noise.

The methods and systems of the present disclosure, as described above and shown in the drawings, provide for shutter actuation with superior properties including improved audible noise characteristics relative to traditional techniques. While the apparatus and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.