Abstract:
A vernier ratchet-type lens adjuster for use with a lens array allows for fine adjustment of the coverage pattern of a sensor. The lens array can have notches, or teeth, that interact with a single tooth, or pawl, of a lens adjuster unit to maintain the position of the lens array. A user can make fine adjustments to the coverage pattern of the sensor by moving the lens array small increments. Alternatively, a rack and pinion type vernier adjuster can be used. One edge of the lens array has notches, forming the teeth of a rack portion. A pinion, or gear, has compatible teeth for mating with the rack portion. The pinion has a knob or screw accessible from a port in the sensor housing. When assembled, the rack, pinion and lens array are mated. A user can adjust the coverage pattern of the lens array by rotating the pinion, which in turn moves the rack, or the lens array, along a predetermined path.

Description:
FIELD OF THE INVENTION 
     The invention relates to an apparatus and method for adjusting the position of a lens array in a motion sensor module. More particularly, the lens array has a series of ribs, or teeth, which engage with a lens adjuster to maintain a desired position. The lens adjuster can be a single tooth or a pawl for engaging with the lens array ribs. A user can slide the lens array to a desired focal point location, and the lens adjuster will maintain the lens array position. Alternatively, the lens adjuster can be a pinion, interacting with ribs forming a rack on the lens array for vernier adjustments. 
     BACKGROUND OF THE INVENTION 
     A need exists to adjust the position of a lens array in a sensor module to eliminate blind spots in the coverage pattern of the sensor module. The coverage pattern of the sensor module determines the zone of coverage, or field of view, of the sensor. 
     Passive infrared sensors are commonly used in motion detectors to determine the presence or absence of individuals, generally determining if someone enters a zone of coverage. These detectors can be connected to security systems alerting others of an intrusion into the zone of coverage. These detectors can also be connected to light switches for turning lights on when a person is present in the zone of coverage, or deactivate the lights when a person is no longer present in the zone of coverage. 
     These motion detectors generally have a passive infrared sensor attached to a printed circuit board contained in a housing. A lens array is positioned in front of the sensor, and focuses the infrared profile of a person or object as it moves across the zone of coverage. The position of the sensor relative to the focal point of the lens array determines the coverage pattern of the sensor. The lens array is generally held in a predetermined position by a lens retainer. However, tolerance buildup during manufacture can alter the predetermined lens position. Consequently, there is a need for a lens adjuster for positioning the lens to eliminate blind spots in the sensor module coverage pattern. 
     Some examples of passive infrared motion detectors are U.S. Pat. No. 5,764,146 to Baldwin et al.; U.S. Pat. No. 4,672,206 to Suzuki et al.; U.S. Pat. No. 5,442,178 to Baldwin; U.S. Pat. No. 5,772,326 to Batko et al.; U.S. Pat. No. 5,790,040 to Kreier et al.; and U.S. Pat. No. 5,026,990 to Marman et al.; and are incorporated herein by reference. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a primary object of the invention to provide an adjustable lens array for use in a motion sensor module. 
     Another object of the invention is to provide a user adjustable lens adjuster for altering and maintaining the position of a lens array in a motion sensor module. 
     Another object of the present invention is to provide a user adjustable lens adjuster for retaining a lens array and altering the position of the lens array relative to a sensor. 
     Yet another objective of the present invention is to provide a user adjustable lens adjuster and a lens array such that the lens array can be repositioned independently along a linear dimension and have the position maintained relative to a sensor. 
     The foregoing objects are basically obtained by providing a lens assembly, comprising: a housing having a lens receiving area, and a first retaining member adjacent the lens receiving area; a lens coupled to the housing within the lens receiving area, the lens having a first lens retaining element, the first retaining element adjustably coupling with the first retaining member; a sensor mounted to the housing and positioned within the housing and behind the lens, wherein the lens is adjustably movable about the sensor between a first position and a second position in a first direction as the first retaining element moves relative to the first retaining member, and the lens is further adjustably movable about the sensor between a third position and a fourth position in a second direction, which is transverse to the first direction, as the second retaining element moves relative to the second retaining member. 
     The objects are flirter obtained by providing a method of adjusting a lens comprising the steps of providing a housing having a lens receiving area, and a first retaining member adjacent the lens receiving area; providing a lens coupled to the housing within the lens receiving area, the lens having a first lens retaining element, the first retaining element adjustably coupling with the first retaining member; providing a sensor mounted to the housing and positioned within the housing and behind the lens, moving the lens about the sensor between a first fixed position and a second fixed position in a first direction. 
     The objects are further obtained by providing a lens assembly, comprising: a housing having an outer surface, a lens receiving area, and a first retaining member adjacent the lens receiving area; a lens coupled to the housing within the lens receiving area, the lens having a first lens retaining element, the first retaining element adjustably coupling with the first retaining member; a sensor mounted to the housing and positioned within the housing and behind the lens, wherein the lens is adjustably movable about the sensor between a first position and a second position in a first direction as the first retaining element moves relative to the first retaining member, and the first retaining member extending from the outer surface of the housing to direct contact with the lens, and the first retaining member being movable between an original position and a final position while engaging the lens to move the lens between the first and second positions. 
     The objects are still further obtained by providing a method of adjusting a lens, comprising the steps of: providing a housing having an outer surface, a lens receiving area, and a first retaining member adjacent the lens receiving area; providing a lens coupled to the housing within the lens receiving area, the lens having a first lens retaining element, the first retaining element adjustably coupling with the first retaining member; providing a sensor mounted to the housing and positioned within the housing and behind the lens; moving the lens about the sensor between a first position and a second position in a first direction as the first retaining element moves relative to the first retaining member by moving the first retaining member. 
     Other advantages and salient features of the invention will become apparent from the following detailed description, which, when taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings which form a part of the original disclosure: 
     FIG. 1 is a front view of an adjustable lens array within a sensor module constructed in accordance with a first embodiment of the present invention; 
     FIG. 2 is a cross-sectional view of the adjustable lens array taken along line  2 — 2  of FIG. 1; 
     FIG. 3 is an enlarged, partial, cross-sectional view of one end of the adjustable lens taken along line  2 — 2  in FIG. 1; 
     FIG. 4 is a cross-sectional view of the adjustable lens array taken along line  4 — 4  of FIG. 1; 
     FIG. 5 is an enlarged, partial, cross-sectional view of the bottom portion of the adjustable lens array taken along line  4 — 4  in FIG. 1; 
     FIG. 6 is a front view of the lens array constructed in accordance with the first embodiment of the present invention; 
     FIG. 7 is a cross-sectional view of the lens array taken along line  7 — 7  in FIG. 6; 
     FIG. 8 is a front view of an adjustable lens array within a sensor module constructed in accordance with a second embodiment of the present invention; 
     FIG. 9 is a cross-sectional view of the adjustable lens array taken along line  9 — 9  in FIG. 8; 
     FIG. 10 in an enlarged view of one end of the adjustable lens array shown in FIG. 9; 
     FIG. 11 is a cross-sectional view of the adjustable lens array taken along line  11 — 11  in FIG. 10; and 
     FIG. 12 is a front view of an adjustable lens array in accordance with the second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1-7 depict a sensor module  10  according to this invention. The sensor module  10  comprises a rear housing member  12  which can be mounted to a mounting surface such as a wall of a house as known in the art, and a front housing member  14  which attaches to the rear housing member  12 . A sensor  16  is mounted on a circuit board  18  within the sensor module  10  as generally known in the art. The sensor  16  can be any perimeter sensor known in the art, such as a passive infrared (PIR) sensor, ultrasonic sensor, temperature sensor, light sensor, relative humidity sensor, a sensor for the detection of carbon dioxide or other gases or ions, an audio sensor, or any other passive or active sensor that can be used to detect movement or change from the nominal environment. For example, the sensor can detect changes in vibration or sound, temperature, visual, ionic and moisture conditions. In the preferred embodiment the sensor  16  is a PIR sensor. 
     An adjustable lens assembly  20  is positioned in front of and in the field of view of the PIR sensor  16  for focusing infrared radiation. The adjustable lens assembly  20  comprises a lens  22  held in position between a lens retainer  24  and a lens adjuster  26 . Lens  22  is preferably a lens array. The adjustable lens assembly  20  is positioned in front of and in the field of view of the PIR sensor  16 , and is mostly visible through an open window  28  or lens receiving area located in the front housing member  14 . When the PIR sensor is used, the lens  22  is preferably a fresnal lens, however, the lens  22  can vary with the type of sensor  16  used. When a PIR sensor is used, the lens  22  focuses IR in the field of view to a focal point at the sensor. The lens retainer  24  is provided for holding the lens  22  in place a predetermined distance from the sensor  16 . The window  28  allows the sensor  16  to view the ambient environment. The lens adjuster  26  interfaces with lens  22  for positioning lens  22  as need for focusing. Except for the adjustable lens array assembly  20 , the structure and functioning of sensor module  10  is generally known in the art. 
     The adjustable lens array assembly  20  allows for a lens  22  to be adjusted horizontally or vertically in order to optimize focusing for the sensor  16 . The lens  22  has an outer perimeter lens portion  30  and an inner lens portion  32 . The outer lens portion  30  has at least one set of ribs or teeth  33  or retaining elements, each set having at least two teeth  34 . 
     The outer perimeter portion  30  of the lens array  22  is generally not used to focus desired ambient parameters for use by the sensor, and is therefore optimum for location of the teeth  34  and other ancillary lens array protrusions and voids. Ribs or teeth  34  are shown approximately centered along the four sides of the outer perimeter portion  30 . Teeth  34  can be in a predetermined orientation to emphasize adjustment in a target direction. The target direction can be vertical or horizontal relative to the mounting position of the sensor module. Additionally, the teeth  34  can be shaped and positioned to result in some rotational movement of the lens  22 . Furthermore, the teeth  34  can be shaped and positioned to result in movement along the Z-axis, that is, away from or towards the sensor  16 . This can most easily occur when only one set of teeth  34  is moved relative to a single lens adjuster  26 . 
     The inner lens portion  32  is the focusing portion of the lens  22  and may have a series of raised nubs  36 . The focusing portion is generally known in the art. The raised nubs  36  allow a user to grip the lens  22  and reposition the lens. 
     Teeth  34  are preferably any shape gear-type teeth known in the art, either attached integrally to the lens  22  or pressed through the lens  22 . When the set of teeth  34  are positioned on a face of the lens  22 , it is preferable that each tooth  34  be located near the middle of each side and near the edge of the lens  22  so as not to interfere with the focusing function of the inner lens portion  32 . 
     The teeth set  34  can be formed as an integral part of the lens  22 , for example, by pressing or molding or the teeth set  33  can be fabricated separately and attached the lens  22  through the use of a fastener. Alternatively, the teeth  34  of the teeth set  33  can be on a carrier to which can be attached to the lens. It is preferable that the teeth set  33  is positioned perpendicular to the direction of adjustment. For example, when horizontal adjustment is desired as shown in FIGS. 2 and 3, it is preferable that the teeth set  33  is positioned vertically. Similarly, when vertical adjustment is desired as shown in FIGS. 4 and 5, it is preferable that the teeth set  33  is positioned horizontally. It is also preferable that when the teeth set  33  are teeth  34 , the teeth  34  are longer than they are wide in order to prevent cocking of the lens array  22  relative to the sensor  16  and the lens adjuster  26 . 
     The lens adjuster  26  is integral with front housing member  14  or attached to the front housing member  14 , using attachment means known in the art, for example, screws, adhesive, glue, and the like. The lens adjuster  26  also has an inside surface  38 . On the inside surface  38  is a single retaining projection  40  for engaging with the teeth  34 . 
     Retaining projection  40  engages, or interlocks with, a pair of teeth of the teeth set  34 . The retaining projection  40  can be a tooth similar to a tooth  34 , a set of teeth, a pawl, or any object of any shape that, when located between a pair of adjacent teeth  34 , prevents the lens  22  from moving to a second lens position  42 . In FIGS. 3 and 5, a lens edge  23  can move to a new edge position  23 A. 
     When the lens adjuster  26  is attached to the front housing  14 , pressure between the teeth  34  on the lens array  22  and the retaining projection  40  is adequate to maintain the position of the lens array  22 , while also allowing the teeth  34  and the retaining projection  40  to slide over each other during adjustment. In this manner, when a set of teeth  34  are positioned to engage a retaining projection  40  along one side of the lens  22 , the lens  22  will not change position along that side until the retaining projection  40  is manually disengaged from the teeth  34 . 
     Nubs  36  on the lens array  22  allow a user to grip the lens array  22  and apply pressure to move the lens array  22  to another position. The user can use finger pressure to grip the nubs  36 , or alternatively the nubs  36  are shaped to receive a screw driver blade or other tool in order to move the lens array  22 . The nubs  36  can be fabricated from the lens array  22 , or can be attached to the lens array  22  in a manner similar to the fabrication or attachment of the teeth  34 , discussed above. Additionally, the nubs  36  are preferably located on the lens array in an area where the nubs  36  will not interfere with the functioning of the lens array  22 . 
     A slot  44  can also be located in the outer lens portion  30  so that an implement can be inserted to effectuate movement of the lens  22 . For example, a user can insert a screwdriver into the slot  44 , and by placing pressure on the lens array  22 , disengage the teeth  34  from the retaining projection  40  of the lens adjuster  26  and force the lens array  22  to move in a desired direction. Teeth  34  reengage with the retaining projection  40  of the lens adjuster  26  when the user stops exerting pressure on the lens array  22 , due to the interest resiliency of lens  22 . 
     Although four teeth  34  are shown in each teeth set  33 , any number greater than two can be used that will allow the lens to be repositioned and held in place. Pressure between the lens retainer  24  and the lens adjuster  26  maintain the position of the lens  22  while also allowing the teeth  34  and the retaining projection  40  to slide over each other during adjustment. In this manner, when the set of teeth  33  are positioned to engage a retaining projection  40  along one side of the lens  22 , the lens  22  will not change position along that side until the lens adjuster  26  is disengaged from the teeth  34  by manual pressure 
     During adjustment of the lens  22 , lens  22  can be moved relative to front housing  14  and to sensor  16 . The movement of lens  22  can be in two substantially perpendicular directions; such as, substantially horizontally and substantially vertically with respect to FIG.  1 . Additionally, the movement of lens  22  can be at an inclined angle relative to the horizontal and vertical axis of FIG.  1 . For example, lens  22  as shown in FIG. 7, can move between two points in a horizontal direction and then in a vertical direction, or a two-step process, or in a direction inclined to the horizontal and vertical positions as a one step process. Of course lens  22  can be moved as little or as much as needed or desired. 
     FIGS. 8-12 depict a second embodiment of this invention. Like part numbers from the first embodiment will be used where applicable. In this second embodiment, the lens adjuster  126  is preferably based on a rack and pinion mechanism. A first set of teeth  46  located on one edge  47  of the lens  122  forms a rack  48 . The type and size of the first set of teeth  46  are predetermined so as to be able to mate with a second set of teeth  50  on the pinion  52 . The first set of teeth  46  can be formed, for example, by cutting out portions of the lens  122 , punching the lens  122  utilizing a die, or attaching a rack having a set of teeth to the edge of the lens  122 . If the first set of teeth  46  are attached by way of a rack to the edge of the lens  122 , the teeth  46  may be formed on a rack of different material from the lens  122 , for example, metal, and attached to the lens  112  using fasteners; such as, glue, adhesive, crimping, rivets, or any other attachment means known in the art. 
     The pinion  52  is preferably a gear having a second set of teeth  50  of similar size to the first set of teeth  46 , and can be fabricated from, for example, metal or plastic. The pinion  52  is attached to a shaft  54  at one end  56 . The shaft  54  passes through a hole  58  in a support block  60  which is attached to the front housing member  14 . On the other end  62  of the shaft  54  is a screw head  64 , which is accessible to a user from outside front housing member  114  through a hole  66  in the front housing member  114 . The pinion  52 , the shaft  54 , and the screw head  64  form a pinion assembly  68 . 
     The pinion assembly  68  is preferably one piece, but can be separate pieces attached by means known in the art, for example, adhesive, glue, welding, cotter pins, threaded nuts, and the like in order to pass the shaft  54  through the support block  60 . For example, the gear portion, or pinion  52 , can be attached to the shaft  54  using, for example, a cotter pin, a locking washer and nut, adhesive, glue, solder, or any other means of attachment known in the art. The pinion assembly  68  can be fabricated from a single piece of material, for example, metal or plastic, but may be fabricated from compatible materials that can be attached as required. 
     The support block  60  can be integrally fabricated concurrently with the front housing member  14 , or can be fabricated separately and attached to any suitable location on the sensor module  10 . 
     In order to retain the shaft  54  in the support block  60 , the support block  60  can be formed around shaft  54  with the larger diameter head  64  and pinion  52 , thus, securing the pinion assembly to block  60 . Alternatively, the pinion assembly can be secured to block  60  and member  114  as known in the art. Other means for retaining the shaft  54  can be used, for example, attaching a threaded nut to the support block  60  at the entrance  70  to the hole  58 . 
     The screw head  64  is accessible through the hole  66  located on the front housing member  114 . When the screw head  64  is rotated by a user, the pinion assembly  68  is likewise rotated, and the rack  48  moves concurrently, which causes the lens  122  to move along the predetermined path  72  by an amount equal to the amount of rotation of the pinion assembly  68 . As shown in FIG. 11, when the lens  122  is moved, side edge  76  travels to a new side edge location  76 A. 
     The screw head  64  can be any common screw head known in the art. Alternatively, the screw head  64  can be replaced with a knob that protrudes from the front housing member  114 . Similarly, a screw head  64  requiring a special device to rotate the pinion assembly  68  can be used, for example, a removable hex key, an allen wrench, a torx wrench, or any other insertion and rotation implement. 
     Additional racks  48  and pinions  52  can be used in a device of the present invention. For example, a rack  48  and pinion  52  can be located on the opposing second edge  74  of the lens  22  for easier adjustment along the horizontal axis of FIG. 8 X-axis. Furthermore, racks  48  and pinions  52  can be placed on the first side edge  76  and the second side edge  78  of lens  22  for adjustment along the vertical axis of FIG.  8 . In this manner, the lens  122  can be moved incrementally amount either side to side or up and down relative to the sensor  16 . 
     During use, the second embodiment permits lens  122  to be moved in one direction by rotating head  64  of pinion  52  from outside front housing  114 . This movement of heat  64  and pinion  52  results in pinion  52  rotating about its longitudinal axis. The movement of head  64  and opinion  52  can be accomplished through the use of a tool, such as a screw driver. As pinion  52  rotates, it engages the rack  48  of lens  122  and moves lens  122  in the direction of the rack  48 , horizontally as shown in FIG.  8 . The pinion  52  can be moved either clockwise or counterclockwise to move lens  122  back and forth in the determined direction until the proper focusing position relative to the sensor  16  is determined. 
     While advantageous embodiments has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.