This disclosure is directed generally to imaging systems. More specifically, this disclosure relates to a variable aperture mechanism for creating different aperture sizes in cameras and other imaging devices.
Digital cameras and other imaging devices typically include an adjustable aperture to control the amount of light reaching an image sensor. Larger apertures allow more light to reach an image sensor, while smaller apertures allow less light to reach an image sensor. Conventional variable apertures often rely on a traditional rotating iris approach in which multiple rotary blades are moved by small piezoelectric motors. Unfortunately, this approach typically requires a larger number of components and complex drive circuitry for the motors. Also, traditional rotating irises typically wear out after a few thousand actuations or a few tens of thousands of actuations, rendering them unsuitable for use in some applications like those requiring hundreds of thousands of actuations. In addition, the blades that form an aperture are often thermally unstable, which can compromise the quality of the imaging device.
This disclosure provides a variable aperture mechanism for creating different aperture sizes in cameras and other imaging devices.
In a first embodiment, an apparatus includes a first blade configured to be coupled to a first magnet and a second blade configured to be coupled to a second magnet. At least one of the blades has at least one cutout. The apparatus also includes electromagnetic motors configured to generate different electromagnetic fields to (i) cause the magnets to move the blades into a first configuration and (ii) cause the magnets to move the blades into a second configuration. The blades are separated to form a larger aperture in the first configuration, and the at least one cutout in the blades forms a smaller aperture in the second configuration.
In a second embodiment, a system includes a variable aperture system and a cooling system. The variable aperture system includes a first blade configured to be coupled to a first magnet and a second blade configured to be coupled to a second magnet, where at least one of the blades has at least one cutout. The variable aperture system also includes electromagnetic motors configured to generate different electromagnetic fields to (i) cause the magnets to move the blades into a first configuration and (ii) cause the magnets to move the blades into a second configuration. The blades are separated to form a larger aperture in the first configuration, and the at least one cutout in the blades forms a smaller aperture in the second configuration. The cooling system is configured to cool at least a portion of the variable aperture system including the blades.
In a third embodiment, a method includes generating first electromagnetic fields that cause magnets to move first and second blades of an aperture mechanism into a first configuration, where the blades are separated to form a larger aperture in the first configuration. The method also includes generating second electromagnetic fields that cause the magnets to move the blades of the aperture mechanism into a second configuration, where at least one cutout in at least one of the blades forms a smaller aperture in the second configuration.
Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims.
For a more complete understanding of this disclosure and its features, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
The device 100 also includes a cooling system 104, a portion of which is shown here. Among other things, the cooling system 104 is used to cool portions of an aperture system 106. The cooling system 104 can cool the portions of the aperture system 106 to any suitable temperature, which could vary depending on the application. In some embodiments, for example, the cooling system 104 could cool portions of the aperture system 106 to a temperature around 100° K. The cooling system 104 includes any suitable structure for cooling one or more components, such as to cryogenic temperatures.
The aperture system 106 adjusts an opening or aperture 108 of the imaging device 100. As shown in
In this example, the aperture system 106 includes an aperture mechanism 110 that adjusts the size of the aperture 108. The aperture system 106 also includes multiple motors 112a-112b and a motor mount 114. As described below, the aperture mechanism 110 includes two blades that can be moved back and forth by the motors 112a-112b to adjust the size of the aperture 108. The motors 112a-112b can generate electromagnetic fields, and magnets in or coupled to the blades can be affected by the electromagnetic fields. This allows the motors 112a-112b to move the blades without actually contacting the blades. The motor mount 114 mounts the motors 112a-112b to the housing 102. In some embodiments, the housing 102, the motors 112a-112b, and the motor mount 114 could be kept at room or ambient temperature, while the aperture mechanism 110 could be kept at a cryogenic or other lower temperature. This enables the aperture mechanism 110 to be thermally isolated from the components at room or ambient temperature, even though the other components are used to adjust the aperture mechanism 110. Additional details regarding the aperture system 106 are provided below.
The imaging device 100 shown here could represent part of any suitable larger device or system. For example, the imaging device 100 could be used as part of an infrared sensor that requires the use of two aperture sizes. The imaging device 100 could also meet various specifications that conventional iris mechanisms are unable to satisfy. For instance, the aperture system 106 could operate over hundreds of thousands of actuations, such as five hundred thousand actuations or more. In addition, the aperture system 106 is able to operate effectively in vacuum environments.
The aperture system 106 can replace more complex rotary iris mechanisms (which may require numerous blades with numerous piezoelectric motors and motor drivers) with a design that uses two movable blades and two electromagnetic motors. This can simplify the design and cost of the aperture system 106. Also, the aperture mechanism 110 can be mounted directly to the cold stage of the cooling system 104, allowing improved temperature control of the aperture mechanism 110. Further, the blades of the aperture mechanism 110 can be captured inside upper and lower plates, providing a simple and physically light design that allows improved temperature control of the blades. Moreover, material selection of components within the aperture system 106 can produce good wear characteristics, neutral coefficient of thermal expansion (CTE) issues, and improved stability at cryogenic temperatures. In addition, the design of the aperture system 106 allows both large and small apertures to be supported by the same aperture system 106, helping to simplify the design of a cold shield or other structure on which the aperture system 106 is mounted.
Although
As shown in
The aperture mechanism here includes two blades 206-208, a cover plate 210, and a base plate 212. The cover plate 210 can be secured to the base plate 212 to thereby define a space between the plates 210-212 for the blades 206-208. The blades 206-208 can move back and forth within this space to alter the size of the aperture 108. Each blade 206-208 includes a semicircular cutout 214, and the cutouts 214 collectively form the smaller aperture 108. Note that semicircular cutouts and circular apertures are for illustration only, and cutouts and apertures could have any other desired shape(s). Also note that the blades 206-208 could have unequal cutouts, or a single blade could have a cutout.
Each blade 206-208 includes any suitable structure defining a portion of an aperture and configured to be moved to change the size of an aperture. Each blade 206-208 could be formed from any suitable material(s) and in any suitable manner. In some embodiments, the blades 206-208 are formed from metal(s) or other thermally conductive material(s) to help maintain a substantially uniform temperature across the blades 206-208. In particular embodiments, the blades 206-208 are formed from beryllium copper and covered with sputtered gold.
The cover plate 210 and base plate 212 include any suitable structures for covering the blades of an aperture mechanism. The cover plate 210 could perform other functions, such as shielding the blades 206-208 from radiation loading and providing a cold conductive path. The base plate 212 could also perform other functions, such as defining the larger size of the aperture 108 and providing a cold conductive path. Each plate 210-212 could be formed from any suitable material(s) and in any suitable manner. In some embodiments, the plates 210-212 are formed from metal(s) or other thermally conductive material(s). In particular embodiments, the plates 210-212 are formed from NITRONIC 60 or other stainless steel alloy.
As shown in
The magnets 220 operate in conjunction with the motors 112a-112b to move the blades 206-208 back and forth. For example, to create a smaller aperture 108, the motors 112a-112b can generate electromagnetic fields with the appropriate north/south pole arrangements to push/pull the magnets 220 towards the center of the aperture mechanism 110. This moves the blades 206-208 inward and narrows the aperture 108. Once the blades 206-208 have moved inward and currents through the motors 112a-112b have stopped, the blades 206-208 can be held in place by the magnetic attraction of the magnets 220 to the nearby portions of the motor cores 202. Similarly, to create a larger aperture 108, the motors 112a-112b can generate electromagnetic fields with the appropriate north/south pole arrangements to push/pull the magnets 220 away from the center of the aperture mechanism 110. This moves the blades 206-208 outward and enlarges the aperture 108. Once the blades 206-208 have moved outward and currents through the motors 112a-112b have stopped, the blades 206-208 can again be held in place by the magnetic attraction of the magnets 220 to the nearby portions of the motor cores 202.
In this example, the cores 202 are curved so that each core 202 has a portion located adjacent to each magnet 220. That is, the motor 112a has a core 202 with one portion next to the magnet 220 of the blade 206 and one portion next to the magnet 220 of the blade 208. Similarly, the motor 112b has a core 202 with one portion next to the magnet 220 of the blade 206 and one portion next to the magnet 220 of the blade 208. In this arrangement, both motors 112a-112b can be used to move the blade 206, and both motors 112a-112b can be used to move the blade 208. Note, however, that each motor 112a-112b could have a core 202 located next to a single magnet 220. In that arrangement, one motor 112a can be used to move the blade 206, and another motor 112b can be used to move the blade 208.
a portion of one core 202 is on one side of each magnet 220 and a portion of the other core is on the opposite side of each magnet 220.
Although
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In
Although
Depending on the implementation, the variable aperture system described above could have various advantages. For example, as shown in
The imaging device determines that it is to operate with a smaller aperture size at step 610. This could include, for example, the controller or other component determining that a smaller aperture size is needed with the infrared sensor or other imaging device. In response, motors are activated to create appropriate north/south poles in the motors' cores at step 612, and the blades of the aperture mechanism are moved inward at step 614. Again, the orientations of the north/south poles in the motors 112a-112b depend on the orientations of the magnets 220 attached to the blades 206-208. This allows the motors 112a-112b to move the blades 206-208 inward without actually contacting the blades 206-208. The blades 206-208 can move inward until they contact the stop pins 402, which prevent the blades 206-208 from moving inward any further. The motors are deactivated at step 616. This stops the motors 112a-112b from creating magnetic north and south poles, but the magnets 220 can remain magnetically attracted to the nearby portions of the cores 222, helping to keep the blades 206-208 locked in their inward positions.
Although
It may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrase “associated with,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The phrase “at least one of,” when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. For example, “at least one of: A, B, and C” includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.
While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.
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