Abstract:
Methods and apparatus for a support mechanism are provided. The support mechanism includes an engagement pin including an engagement surface and a latch surface wherein the engagement pin is coupled to a base. The support mechanism also includes a pawl that includes an engagement surface complementary to the pin engagement surface and a latch surface complementary to the pin latch surface wherein the pawl is biased toward engagement of the pawl latch surface with the pin latch surface. The support mechanism also includes a ring latch that includes an annular ring having a toothed edge, the ring latch is coupled to the pawl such that the pawl extends axially away from the ring latch in a direction opposite the toothed edge.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates generally to video surveillance systems and, more particularly, to assembling and disassembling camera pan, tilt, and zoom assemblies.  
         [0002]     At least some known video surveillance systems include one or more video cameras mounted in a housing along with a pan, tilt, and zoom (PTZ) assembly. The PTZ permits controlling a movement of the camera to align a viewing area of the camera with an object of interest or location of interest. The zoom portion of the mechanism may be used to adjust a field of view of the camera. The housing protects the camera from the environment in the location where the camera and PTZ assembly are mounted.  
         [0003]     During initial installation and periodically thereafter, the camera and/or PTZ assembly may need to be removed from it&#39;s mounted location. For example, over time, the camera and/or PTZ assembly may require maintenance to restore a damaged or worn camera or PTZ assembly to an operable condition. When installing, repairing, or replacing a PTZ assembly a maintenance person is frequently required to use two hands to unlatch the mechanism that supports the PTZ assembly and remove it from its housing. At least some known PTZ assemblies are positioned in an elevated location, therefore using two hands to remove the PTZ assembly creates a safety hazard. In addition, when installing, repairing, or replacing a PTZ assembly a maintenance person is frequently required to push and/or pull with a great amount of force to install or remove the PTZ assembly from its housing. Such actions can cause a safety hazard by unbalancing a person high in the air on a ladder or lifting mechanism. Requiring the use of a man-lift or other lifting mechanism, so that two hands may be used also increases the cost of removing and installing the camera and PTZ assembly.  
         [0004]     At least some known PTZ assemblies are compact in size such that various hazards can arise from placing a hand into these mechanisms, for example, to loosen fasteners, catches, and/or latches, or during insertion and removal of the PTZ assembly. A part of the PTZ assembly falling from the elevated mounting position can create a safety hazard as well. A PTZ assembly falling from an elevated position could cause death or serious bodily injury such that positive control and installation of the PTZ assembly is required. At least some known PTZ attachment mechanisms create a “false positive” indication of attachment, such that the user believes the mechanism is securely attached in place when it is not.  
         [0005]     A previous attempt to address the afore mentioned problems included a radial handle located inside the PTZ assembly housing. When pulled, the handle would engage symmetrical pawls on leaf springs releasing the PTZ mechanism. However, an uneven distribution of downward forces, sometimes caused binding between the engaged components and inserting a hand into the housing created a safety hazard for the user and limited the compactness of the design. A second attempt to address the problems described above included a toothed bracket that was constrained to linear motion tangent to a shroud of the PTZ assembly. The shroud was also toothed, and when engaged, the teeth would align and the bracket could be moved. The bracket included a wedge design that would move over a stubby nose spring plunger, creating the upward force necessary to hold the PTZ assembly in place. However, the linear motion of the bracket causes binding because the motion of the shroud was radial and the latching of the PTZ assembly is not positive such that the user is required to apply a force to engage the latch.  
       BRIEF DESCRIPTION OF THE INVENTION  
       [0006]     In one embodiment, a support mechanism is provided. The support mechanism includes an engagement pin including an engagement surface and a latch surface wherein the engagement pin is coupled to a base. The support mechanism also includes a pawl including an engagement surface complementary to the pin engagement surface and a latch surface complementary to the pin latch surface wherein the pawl is biased toward engagement of the pawl latch surface with the pin latch surface. The support mechanism also includes a ring latch that includes an annular ring having a toothed edge, the ring latch is coupled to the pawl such that the pawl extends axially away from the ring latch in a direction opposite the toothed edge.  
         [0007]     In another embodiment, a support mechanism is provided. The support mechanism includes a base, a pan motor having a longitudinal axis, and a removable unit. The pan motor includes a stationary member coupled to the base and a rotatable member rotatably coupled to the stationary member. The removable unit is configured to latchably couple to the base using a first axial force applied to the removable unit. The removable unit is also configured to release from the base using a second axial force and a rotational force in sequential combination.  
         [0008]     In yet another embodiment, a method of operating a support mechanism is provided. The support mechanism includes a base and a removable unit latchably coupled to the base. The method includes engaging a rotatable toothed shroud to a toothed ring latch using a an axial force to reposition the shroud from a relaxed position to an engaged position, rotating the shroud and ring latch using a rotational force applied to the shroud to unlatch the removable unit from the base, and withdrawing the removable unit from the base using at least one of the weight of the removable unit and an ejection bias member. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a perspective view of an exemplary video camera pan, tilt, and zoom assembly in accordance with an embodiment of the present invention;  
         [0010]      FIG. 2  is an enlarged perspective view of a portion of the PTZ assembly shown in  FIG. 1 ;  
         [0011]      FIG. 3  is an enlarged perspective view of an alternative embodiment of a portion of the PTZ assembly shown in  FIG. 1 ;  
         [0012]      FIG. 4  is a perspective view of the exemplary PTZ assembly shown in  FIG. 1  with parts removed;  
         [0013]      FIG. 5  is a perspective view of the exemplary PTZ assembly shown in  FIG. 1  with different parts removed than shown in  FIG. 3 ; and  
         [0014]      FIG. 6  is a flowchart of an exemplary method of operating a support mechanism that includes a base and a removable unit latchably coupled to the base. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]     As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.  
         [0016]      FIG. 1  is a perspective view of an exemplary video camera pan, tilt, and zoom assembly  100  in accordance with an embodiment of the present invention. PTZ assembly  100  includes an upper bracket or base  102  coupled to an interior portion of a housing. The housing is configured to be fixedly coupled to a structure such as a ceiling, stanchion, post, or other suitable mount able to support the weight of PTZ assembly  100  and is a stable platform to facilitate reducing jitter. Jitter may be apparent in the camera image due to vibration or swaying of PTZ assembly  100 .  
         [0017]     Base  102  includes one or more locating rounds  104  that are complementary to locating slots  106  in a lower bracket  108  of a removable unit  110 . Locating rounds and locating slots  106  are used to align removable unit  110  and base prior to coupling removable unit  110  to base  102 . Base  102  also includes one or more guides  112  configured to receive a pawl  114  coupled to a ring latch  116  on removable unit  110 . In the exemplary embodiment, a second pawl (not shown) is oriented similarly to pawl  114  and spaced approximately 180 degrees from pawl  114 . In an alternative embodiment, a different number of pawls are used. A distal end  118  of guide  112  includes a pin  120  extending away from guide  112  in a radial direction with respect to a longitudinal axis  122  of PTZ assembly  100 . Pawl  114  and pin  120  are configured to engage to transfer the weight of removable unit  110  to base  102  to support removable unit  110 . In various embodiments of the present invention pin  120  is configured as a rotatable wheel.  
         [0018]     Ring latch  116  is rotatably coupled to lower bracket  108 . The amount of rotation ring latch  116  is capable of is limited by a plurality of stops  123  and complementary grooves  124  that engage to limit the rotational travel of ring latch  116  with respect to lower bracket  108 . A stationary member  128  of pan motor  126  is fixedly coupled to lower bracket  108 . When pan motor  126  rotates, removable unit  110  rotates with the rotatable member and with respect to base  102 . A slip ring  130  permits removable unit  110  to rotate continuously in a first rotational direction  132  or a second opposite direction  134 .  
         [0019]     Removable unit  110  includes a shroud  136  that is slidably coupled to a chassis  137 . Shroud  136  is configured to maintain a relaxed position (shown in  FIG. 1 ) and an engaged position. In the engaged position, a plurality of teeth  138  arranged circumferentially about an outer periphery  140  of shroud  136  and extending axially toward ring latch  116  are configured to mesh with a complementary plurality of teeth  142  arranged circumferentially about an outer periphery  144  of ring latch  116  and extending axially toward teeth  138 . Shroud  136  is translated from the relaxed position to the engaged position by applying an upward axial force to a bottom side  146  of shroud  136 . The movement associated with positioning shroud  136  from the relaxed position to the engaged position compresses or tensions a plurality of bias members  148  coupled between shroud  136  and chassis  137 . A plurality of travel limiters  147  limit the upward movement of ring latch  116  with respect to lower bracket  108 . Bias members  148  are configured to return shroud  136  to the relaxed position when the axial force applied to shroud  136  is removed.  
         [0020]     Ring latch  116  is configured to rotate at least partially about axis  122  and shroud  136  is configured to rotate freely about axis  122  with chassis  137  and the rotatable member of pan motor  128 . Accordingly, with teeth  138  and  142  engaged by an axial force applied to shroud  136 , an additional rotational force may be applied to shroud  136  to cause ring latch to rotate. Pawl  114  rotates with ring latch  116  toward or away from pin  120 . If pawl  114  rotates away from pin  120 , the weight of removable unit  110  will no longer be supported by the engagement of pawl  114  and pin  120  and removable unit  110  will be released from base  102  by its own weight. In an alternative embodiment, one or more ejection springs are configured to apply a bias force to removable unit  110  to assist in disengaging removable unit  100  from base  102 .  
         [0021]      FIG. 2  is an enlarged perspective view of a portion of PTZ assembly  100  (shown in  FIG. 1 ). Pawl  114  extends axially away from ring latch  116  toward guide  112 . Pawl  114  includes an engagement surface  202  and latch surface  204 . Pin  120  extends radially from guide  112  and includes an engagement surface  206  and a latch surface  208 . Engagement surface  206  is configured to engage engagement surface  202  during an installation procedure where removable unit  110  is coupled to base  102 . A tip  210  of pawl  114  has a width  212  that is less than a width  214  of a root end  216  of pawl  114 . As pawl  114  moves axially with respect to pin  120  during the installation procedure, engagement surface  206  engages engagement surface  202  and a rotational force generated by the inclined engagement surface  202  and stationary engagement surface  206  forces pawl  114  to move away from pin  120 , which compresses a bias member  218 . In the exemplary embodiment, bias member  218  is a coil spring. In various alternative embodiments, bias member  218  is a leaf spring, an extension spring, a constant force spring, or a resilient material.  
         [0022]     Latch surface  208  is configured to engage latch surface  204  after engagement surface  202  clears engagement surface  206 . Bias member  218  provides a rotational force to slide latch surface  204  over latch surface  208  such that the weight of removable unit  110  is transferred to pin  120  from pawl  114 .  
         [0023]     In  FIG. 2 , pin  120  is illustrated as a wedge-shape pin, in various alternative embodiments, pin  120  is a rotatable wheel that rolls along engagement surface  202  rather than sliding across it. The wheel is configured to engage latch surface  204  after the wheel clears engagement surface  202  during an installation procedure. A radially outer periphery of the wheel corresponds to engagement surface  206  and latch surface  208  and engages engagement surface  202  and latch surface  204 .  
         [0024]      FIG. 3  is an enlarged perspective view of an alternative embodiment of a portion of PTZ assembly  100  (shown in  FIG. 1 ). In this embodiment, a pin  264  extends axially away from ring latch  266  toward a guide  268 . Pin  264  includes an engagement surface  270  and latch surface  272 . A pawl  274  extends from guide  268  and includes an engagement surface  276  and a latch surface  278 . Engagement surface  276  is configured to engage engagement surface  270  during an installation procedure where removable unit  110  is coupled to base  102 . A tip  280  of pawl  274  has a width  282  that is less than a width  284  of a root end  286  of pawl  274 . As pin  264  moves axially with respect to pawl  274  during the installation procedure, engagement surface  270  engages engagement surface  276  and a rotational force generated by the inclined engagement surface  270  and stationary engagement surface  276  forces pin  264  to move away from pawl  274 , which compresses a bias member  288 . In the exemplary embodiment, bias member  288  is a coil spring. In various alternative embodiments, bias member  288  is a leaf spring, an extension spring, a constant force spring, or a resilient material.  
         [0025]     Latch surface  272  is configured to engage latch surface  278  after engagement surface  270  clears engagement surface  276 . Bias member  288  provides a rotational force to slide latch surface  272  over latch surface  278  such that the weight of removable unit  110  is transferred to pawl  274  from pin  264 .  
         [0026]     In  FIG. 3 , pin  264  is illustrated as a wedge-shape pin, in various alternative embodiments, pin  264  is a rotatable wheel that rolls along engagement surface  276  rather than sliding across it. The wheel is configured to engage latch surface  278  after the wheel clears engagement surface  276  during an installation procedure.  
         [0027]      FIG. 4  is a perspective view of exemplary PTZ assembly  100  (shown in  FIG. 1 ) with parts removed. Specifically, PTZ assembly  100  is illustrated with base  102 , shroud  136 , and ring latch  116  removed. PTZ assembly  100  includes a tilt motor  302  coupled to chassis  137  and to a video camera  304  such that a rotation of tilt motor  302  defines a tilt angle of camera  304  with respect to axis  122 . A plurality of tabs  306  extending radially away from lower bracket  108  support ring latch  116  in an axial direction and are configured to permit ring latch  116  to rotate.  
         [0028]      FIG. 5  is a perspective view of exemplary PTZ assembly  100  (shown in  FIG. 1 ) with different parts removed than shown in  FIG. 3 . Specifically, PTZ assembly  100  is illustrated with base  102 , lower bracket  108 , and ring latch  116  removed. PTZ assembly  100  includes a rotatable member  402  of motor  128  coupled to chassis  137  such that a rotation of pan motor  128  defines a rotation of chassis  137  about axis  122 .  
         [0029]      FIG. 6  is a flowchart of an exemplary method  500  of operating a support mechanism that includes a base and a removable unit latchably coupled to the base. In the exemplary embodiment, the removable unit is a PTZ assembly configured to support a video camera and permit rotation of the camera field of view about a pan axis and a tilt axis. The removable unit includes a pawl and pin latch mechanism that permits attachment of the removable unit to the base using a force acting along the pan axis, such as by a user&#39;s hand supporting the removable unit and the user supplying an upward force from the bottom of the removable unit. To release the removable unit, an upward force is applied to the bottom of the removable unit to engage two sets of teeth. A rotation force is then applied to the removable unit to unlock the pawl and pin latch mechanism. The rotational force is transmitted through the meshed teeth to move the pawl from a latched position to an unlatched position with respect to the pin. The weight of the removable unit permits the removable unit to separate from the base with substantially no additional force required.  
         [0030]     To release the removable unit of an assembled PTZ assembly, method  500  includes engaging  502  a rotatable toothed shroud to a toothed ring latch using a an axial force to reposition the shroud from a relaxed position to an engaged position, rotating  504  the shroud and ring latch using a rotational force applied to the shroud to unlatch the removable unit from the base, and withdrawing  506  the removable unit from the base using the weight of the removable unit.  
         [0031]     To install the removable unit to the base, method  500  includes aligning  508  a locating round of the base with a complementary locating socket of the removable unit, and latchably coupling  510  the removable unit to the base using an axial force applied to the shroud on a side opposite the base.  
         [0032]     Although the embodiments described herein are discussed with respect to a video surveillance system, it is understood that the coupling and release mechanism described herein may be used with other mechanical and electro-mechanical systems.  
         [0033]     It will be appreciated that the use of first and second or other similar nomenclature for denoting similar items is not intended to specify or imply any particular order unless otherwise stated.  
         [0034]     The above-described embodiments of a video surveillance system provide a cost-effective and reliable means for a latching mechanism that allows the PTZ assembly to be installed and removed using only one hand, thus allowing the user to keep one hand secured to a ladder or lifting mechanism, and that requires a relatively small amount of upward force to install and substantially zero downward force to remove. The latching mechanism also operates such that the user&#39;s hand only comes in contact with the shroud to facilitate reducing pinch points and crush points and does not create a false positive installation indication.  
         [0035]     Exemplary embodiments of video surveillance systems and apparatus are described above in detail. The video surveillance system components illustrated are not limited to the specific embodiments described herein, but rather, components of each system may be utilized independently and separately from other components described herein. For example, the video surveillance system components described above may also be used in combination with different video surveillance system components. A technical effect of the various embodiments of the systems and methods described herein include facilitating operation and maintenance of video surveillance system by permitting relatively simple interchangeability and maintenance of cameras.  
         [0036]     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.