Patent Publication Number: US-9891612-B2

Title: Intermediate linear positioning

Description:
TECHNOLOGY FIELD 
     The present invention relates generally to positioning items. More specifically, an embodiment of the present disclosure relates to an intermediate linear positioning of loads by a linear positioning system. 
     BACKGROUND 
     Generally speaking, linear positioning is useful in a number of technical, industrial and commercial applications. For example, linear positioning of lenses provides zoom focus capability in scanners, which may be used for reading bar code patterns and documents, from which data presented in two dimensional (2D) graphic media may be accessed. 
     Linear position control is provided by systems that have actuation components (“linear actuators”). The simplest linear actuators move a load item (“load”) from a first position to a second position along an axis of translational motion. The load may also be moved from the second position to the first position. 
     Some linear actuators may thus be operable in a forward direction (from the first position to the second position) and a reverse direction (from the second position to the first position). Somewhat more complex linear actuator may move the load, forward and reverse, between the first and the second positions, and to one or more additional positions. 
     For example, linear actuators used with three (3) position mechanical zoom move the load to a third position. The third position may be disposed along the translational axis at an intermediate point between the first position and the second position, which thus correspond to opposite extremes of movement of the load. 
     The actuator may move the load back and forth between hard stops at each of the first and the second positions, but not beyond either. Further, the actuator may move the load to a hard stop at the intermediate third position, from which it may then move the load to either of the first or the second positions. 
     The hard stops comprise positions at which the movement of the load is stopped and temporarily constrained from moving further in either direction. The hard stops of the first and the second positions are disposed at opposite fixed positions along the axis, which the linear actuator is constrained not to exceed. 
     The hard stop of the third position may correspond to a particular intermediate location as precise as the fixed locations of the first and the second positions. However, the actuator is operable for moving the load from the stop at the third intermediate position to the first and/or to the second position. 
     Lacking the fixed locations of the first and the second positions, the location of the intermediate third position must be designated with a precision level sufficient for a given use application. Effectively reliable linear positioning demands consistent repeatability in the achieving the sufficient precision level. 
     To attain the consistent repeatability, one or more additional position indicating components (“position sensors”) may typically be used with the linear positioning system. The position sensors are operable for designating the precise location along the linear translational axis at which to stop the load in the intermediate position. 
     As the actuator moves the load over the linear axis, the position sensor tracks the load&#39;s changing position. Upon sensing that the load has been moved into the precise intermediate position, the motion of the load may be selectively stopped, and held in that position for as long a duration as may be selected. 
     Stopping the load in the first position and the second position is relatively simple, as these opposite motion limits are fixed. The complexity level rises significantly however in relation to stopping the load at the comparatively non-fixed intermediate third position. For example, the sensor first tracks the load as it is moved by the actuator. 
     Responsive to detecting that the load reaches the intermediate position, the sensor functions to trigger a stoppage of the motion of the load in that position. However, effects such as latency related to combining the operations of the position sensor and triggering the stop may impact the achievable precision level and/or its repeatability. 
     Moreover, the addition of the position sensors adds cost and complexity to the linear positioning systems. In addition to the impacted precision or reliability, the increased complexity of the linear positioning systems may add concomitant reliability issues or exacerbate existing ones associated therewith. 
     The additional cost and complexity associated with adding the position sensors to the linear positioning systems may be prohibitive for use in some applications. For example, 3-position mechanical zoom features may add significant functionality to simple, inexpensive optical scan engines, if sufficient precision is achievable consistently. 
     The linear position control in these scan engines must function at a designated level of precision and repeatability in delineating the intermediate position for stopping the movement of the load by the linear actuators. However, adding position sensors to the linear positioning systems of such scanners raises their cost and complexity prohibitively. 
     Moreover, latency and other precision and repeatability related effects added by the use of the position sensors with the linear positioning systems may also complicate their design and construction. The added complication may, of course, raise costs further and pose concomitant additional reliability issues. 
     SUMMARY 
     Therefore, a need exists for moving a load along a linear axis, over which the load may be stopped at least one position disposed at an intermediate point between opposing motion limit positions. A need also exists for moving the load bi-directionally along the linear axis between the at least one intermediate position and the positions of either of the motion limits and to stop at any of the positions, within a repeatable level of precision sufficient for a given use application. Further, a need exists for stopping the movement of the load at the intermediate position, within the sufficient repeatable precision level, independent of any dedicated position sensors. 
     Accordingly, in one aspect, the present invention embraces a system is described for positioning a load in of multiple positions disposed over a linear axis. A linear actuator moves the load into each of the positions. A first position is at an end of the movement, with a second position opposite. A third position is intermediate between the first and the second positions. A stop actuator is made of a configurable material switchable selectively between an engaged configuration, in which the load is positioned in the at least third position, and a disengaged configuration, in which the load is freely movable between the first and the second positions. 
     In an example embodiment, the system is used in an optical apparatus, such as a scanner for bar codes and/or other sources of 2D graphic data. The apparatus comprises an assembly of lenses, in which a movable lens comprises the load. The system is operable for positioning the movable lens in the first or second positions, which correspond respectively to an extended range and an ‘HD’ range of high definition and near-field and far-field reading of high density bar codes.— 
     An example embodiment may be implemented in which the switchably configurable material comprises an electroactive polymer (EAP), which may be active electostrictively. An example embodiment may also be implemented in which the switchably configurable material comprises a shape-memory alloy (SMA). The SMA material may be drawn into a wire or another structure. 
     In another aspect, the present invention embraces a zoom component, such as for use as a component in an optical or other apparatus. 
     In an example embodiment, the optical apparatus comprises a scanner for bar codes or other 2D graphic data. 
     In yet another aspect, the present invention embraces a method for adjusting a focus range of an optical apparatus such as a scanner. A linear actuator is actuated, which is operable for impelling a motion of a movable lens of the optical apparatus over a linear translational axis between a first position on the axis and a second position opposite therefrom. The first and the second positions each comprise limits of the motion of the movable lens in respective opposite directions over the axis. 
     The method also comprises selectively disengaging a stop actuator, in which the motion of the load is unconstrained between the first the second positions. The method also comprises selectively disengaging a stop actuator, in which the motion of the load is unconstrained between the first the second positions. Positioning the movable lens in the second position corresponds to operating the scanner in the HD focus range. 
     Further, the method comprises selectively engaging the stop actuator. The engaged stop actuator is operable for positioning the movable lens in at least an intermediate third position disposed along the axis between the first and the second positions. Positioning the movable lens in the intermediate position corresponds to operating the scanner in an SR focus range 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts an example linear positioning system, according to an embodiment of the present invention; 
         FIG. 2  depicts an example stop actuator component for the linear positioning system, according to an example embodiment of the present invention; 
         FIG. 3A  and  FIG. 3B  each depict an example scanner with a movable lens positioned at respective opposite motion limits, according to an example embodiment; 
         FIG. 3C  depicts the example scanner with a movable lens positioned at an intermediate position, according to an example embodiment; 
         FIG. 4  depicts an example optical scanner apparatus, according to an example embodiment; 
         FIG. 5A  and  FIG. 5B  each depict an example formed SMA stop actuator device in respective stop-engaged and disengaged configurations, according to an example embodiment; 
         FIG. 6A  and  FIG. 6B  each depict an example wire SMA stop actuator device in respective stop-engaged and disengaged configurations, according to an example embodiment; 
         FIG. 7A  and  FIG. 7B  each depict an example EAP stop actuator device in respective stop-engaged and disengaged configurations, according to an example embodiment; 
         FIG. 8  depicts an example N-position linear positioning system, according to an embodiment; and 
         FIG. 9  depicts a flowchart for an example linear positioning process, according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
     The present invention embraces moving a load along a linear axis and stopping the load at one or more intermediate positions disposed between opposite motion limit positions. An example embodiment relates to moving the load bi-directionally along the linear axis between the one or more intermediate positions and the positions of either of the motion limits and stopping the load at any of these positions, within a repeatable level of precision sufficient for a given use application. Moreover, example embodiments stop the movement of the load at the one or more intermediate positions, within the sufficient repeatable precision level, without using a dedicated position sensor. 
     An example embodiment is described in relation to a system for positioning a load in of multiple positions disposed over a linear axis. A linear actuator moves the load into each of the positions. A first position is at an end of the movement in a first direction, with a second position opposite. A third position is intermediate between the first and the second positions. A stop actuator is made of a configurable material switchable selectively between an engaged configuration, in which the load is positioned in the at least third position, and a disengaged configuration, in which the load is freely movable between the first and the second positions. The load may comprise a movable lens in an optical assembly (e.g., zoom focus) or an apparatus (e.g., a scanner). 
     To achieve the desired levels of zoom in an optical apparatus, or indeed a desired outcome in any application, example embodiments of the present disclosure allow the actuation functions of linear positioning systems to position items moved therewith within a narrow band of precision, and do so repeatedly. 
     Scanners are used for reading bar code patterns, imaging documents and accessing 2D data presented with other graphic media. The scanners, and various other optical apparatus, function with associated systems of lenses, operable for collecting and focusing light. Such lens systems have at least a first lens and an image sensor-side lens. 
     An embodiment of the present invention relates to an optical apparatus and/or a scanner with multiple focusable fields of view (e.g., “zoom”) using a lens system. One or more features of the optical apparatus, the scanner and/or the lens assembly may be implemented as described in U.S. Patent Application Publication No. 2014/0084068 by Gillet, et al., which is incorporated by reference for all purposes as if fully set forth herein and any patent(s) that may subsequently or eventually issue in relation thereto. 
     The first lens is stationary and oriented towards a target object. The first lens thus gathers light incident thereto. The incident light comprises a light beam emitted or reflected by the target object. The first lens focuses the incident light beam upon a focal point disposed along a longitudinal axis of the lens system. 
     Rays of the beam diverging from the focus are then captured and re-focused by a second sensor side lens upon an image sensor such as a charge coupled device (CCD) image detector array, a complementary metal oxide semiconductor (CMOS) image sensor array, or a detector comprising a photodiode (PD) array. The second sensor side lens is stationary (or perhaps movable only minimally). 
     A third lens is disposed between the first lens and the second sensor side lens. The third lens is moveable to various positions, which are disposed between the first lens and the second sensor side lens. 
     Foci of the lens system are adjusted to achieve desired levels of zoom. The foci are adjusted by controlling the position of the moveable third lens, relative to the stationary first lens and second sensor side lens. The movable lens position may be adjusted using a linear positioning system. 
     An Example Linear Positioning System 
       FIG. 1  depicts an example linear positioning system  10 , according to an embodiment of the present invention. Linear positioning system  10  is operable for moving a load  19 , such as a movable lens in an optical zoom lens assembly, over a linear axis of motion  14 . Linear positioning system  10  comprises a linear actuator component  15 . The linear actuator  15  is operable, controllably, for moving the load  19  into a plurality of positions disposed over the linear axis  14 , which relates to a motion of the load  19 . The plurality of positions comprises a first position  11  and a second position  12 . The moving of the load  19  and/or one or more other operations and other features of the linear positioning system  10  may be implemented, for example, according to one or more features described in U.S. Pat. No. 8,976,368, by El Akel, et al., which is incorporated by reference herein in its entirety and for all purposes. 
     The first position  11  is disposed at a first end of the linear axis  14 , which corresponds to a limit of the motion of the load  19 . The second position  12  is disposed at a second end, opposite to the first end, of the linear axis  14 , which corresponds to a limit of the motion of the load  19  in a second direction of motion opposite to the first direction of motion. The plurality of positions also comprises at least a third position  13  disposed along the linear axis at an intermediate point between the first position and the second position. 
     A stop actuator component  16  of the system  10  comprises a switchably configurable material. The configurable material switches, selectively, between a first ‘disengaged’ configuration and a second ‘engaged’ configuration. In the disengaged (first) configuration, the motion of the load is unconstrained between the first position  11  and the second position  12 . In the engaged (second) configuration, the stop actuator  16  is operable for a stopping the motion of the load  19  in the at least third position, where the load  19  remains while the stop actuator  16  is operably engaged. 
     The linear actuator component  15  may comprise a tiny ultrasonic linear actuator (TULA) device. The switchably configurable material may comprise a metallic composition or a polymeric composition. An example embodiment may be implemented in which the switchably configurable material of the stop actuator  16  comprises an electroactive polymer (EAP) such an electrostrictive polymer. An example embodiment may also be implemented in which the switchably configurable material comprises a shape-memory alloy (SMA). A form of the SMA material may be fabricated as a gate structure, or as a wire structure. 
     In an example embodiment, the load  19  comprises a movable lens in a zoom focus element of an optical apparatus. The zoom focus element is operable selectively over an HD focus range of high definition and near-field and far-field reading of high density bar codes. 
     The zoom focus element comprises a first lens, fixed in proximity to the second position, and an image sensor-side lens, fixed in proximity to the first position. The position in which the movable lens is stopped corresponds to the focus range selected, over which the zoom focus is operable. 
     For example, upon a stop of the movable lens in the first position, the zoom element is operable in the ER. Upon a stop of the movable lens in the second position, the zoom element is operable in the SR. Upon the stopping the motion of the load in the at least third position, the zoom element is operable in the HD focus range. The stop actuator  16  is operable for stopping the movable lens in the intermediate position with a level of precision sufficient for use in repeatably accurate and reliable optical scan operations, without cost and/or complexity associated with alternative use of intermediate position indicating means. 
     Linear positioning system  10  may comprise one or more additional stop actuator components and the plurality of positions may comprise one or more respectively corresponding intermediate positions along the linear axis  14 . The additional intermediate positions are disposed between the third position and either the first position, or the second position. Each of the additional stop actuator components comprises one of the switchably configurable materials, and each is operable in its engaged (second) configuration for stopping the motion of the load  19  at the respectively corresponding additional position. 
       FIG. 2  depicts an example stop actuator component  16  for the linear positioning system  10 , according to an example embodiment of the present invention. The stop actuator  16  comprises a switching mechanism  25  and a dimorphic component  26 . The dimorphic component  26  comprises a switchably configurable material  26 , such as an SMA or an EAP. The switching mechanism  25  is operable as an intermediate position selector  21  and as a selector  29  of the motion limits. 
     With the motion limit selection  29 , the switching mechanism  25  switches the configurable material  25  into a ‘disengage’ configuration  27 . Thus, the stop actuator  16  is disengaged and freely allows the load  19  to move, unconstrained, between the first position  11  and the second position  22 , or vice versa. 
     With the intermediate position selection  21 , the switching mechanism  25  switches the configurable material  25  into an ‘engage’ configuration  22 . Thus, the stop actuator  16  is engaged and stops the load  19  in the intermediate position. 
     Switching the dimorphic material  26  between the engage configuration and the disengage configuration comprises selectively changing its shape between each of two contours respectively corresponding to each. 
     With EAP materials, the switching mechanism  25  is operable for selectively changing the shape of the dimorphic material by varying an electrostatic field in which the EAP is disposed piezoelectrically. With SMA materials, the switching mechanism  25  is operable for selectively changing the shape of the dimorphic material between a native, initial and/or non-deformed contour and a deformed contour by means of a thermomechanical mechanism. 
     As used herein, the term ‘thermomechanical’ refers to mechanical means (e.g., deformation, spring loading), used in combination with heating and cooling. The thermomechanical mechanism manipulates the internal microstructure and corresponding metallurgical characteristics of the SMA material. The thermomechanical mechanism, for example, effectuates transitions between austenite and martensite crystal lattice structures of the SMA, which change the shape of the dimorphic component  25 . 
     Selecting for the linear actuator  15  to position the load  19  in the first position  11  or the second position  12 , the motion limit selector  29  is operable for switching the configurable material  26  of stop actuator  16  accordingly. The switching mechanism  25  thus operates as the motion limit selector  29  to provide a ‘disengage’ selection  27 , based on which the switchably configurable material  26  is switched to configure the stop actuator  16  to disengage. Disengaging the stop actuator  16  allows the linear actuator  15  to move the load  19  freely, unconstrained between the first position  11  and the second position  12 . 
     Selecting for positioning the load  19  in the intermediate third position  13 , the motion limit selector  29  is operable for switching the configurable material  26  of stop actuator  16  accordingly. The switching mechanism  25  operates as the intermediate position selector  21  to provide an ‘engage’ selection  22 , based on which the switchably configurable material  26  is switched to configure the stop actuator  16  to engage. Upon engagement, the stop actuator  16  is operable for a stopping the motion of the load  19  in the at least third position  13 , where the load  19  remains while the stop actuator  16  is operably engaged. 
     As the engagement of the stop actuator  16  halts the motion of the load  19  in the at least third position  13 , where the load  19  remains while the stop actuator  16  is operably engaged, an example embodiment may thus be implemented to configure an SR focus range for the zoom focus element in the optical apparatus. 
     Thus, a system is described for positioning a load in of multiple positions disposed over a linear axis. A linear actuator moves the load into each of the positions. A first position is at an end of the movement, with a second position opposite. A third position is intermediate between the first and the second positions. A stop actuator is made of a configurable material switchable selectively between an engaged configuration, in which the load is positioned in the at least third position, and a disengaged configuration, in which the load is freely movable between the first and the second positions. 
     Example Optical Assembly 
     An example embodiment is described in relation to an optical assembly, which is adjustable, selectively, over at least three focus ranges.  FIG. 3A  and  FIG. 3B  each depict an example optical assembly  30  with a movable lens component  39  positioned at respective opposite motion limits  11  and  12 , according to an example embodiment.  FIG. 3C  depicts the example optical assembly  30  with the movable lens component  39  positioned at an intermediate third position  13 , according to an example embodiment. The movable lens  39  comprises a load (e.g.,  19 ;  FIG. 1, 2 ) of the optical assembly  30 . 
     The optical assembly  30  comprises a first lens  37 , which is fixed in proximity to the second position  12 . The optical assembly  30  also comprises an image sensor-side (“ocular”) lens  38  fixed in proximity to the first position  11 , which is disposed at an opposite end of a linear axis of the optical assembly  30  from the first position and in proximity with an image detector  402 , such as a CCD, etc. 
     Further, the optical assembly  30  comprises a lens  39 , which is movable controllably over the linear axis between the first position  11  and the second position  12 . Positioning the movable lens  39  in the second position  12  selects an HD focus range of high definition and near-field and far-field reading of high density bar codes for the optical assembly  30 . Positioning of the movable lens  39  in the first position  11  selects an extended focus range (ER) of the optical assembly  30 . 
     The third position  13  is disposed between the first position  11  and the second position  12 . Positioning the movable lens  39  in the third position  13  selects a corresponding SR focus range. 
     In an example embodiment, one or more features of the optical assembly  30  may be implemented as described in the incorporated reference: U.S. Pat. Appl. Pub. No. 2014/0084068 by Gillet, et al. 
     The optical assembly  30  comprises a zoom mechanism operable for positioning the movable lens  39 , selectively, over the first position  11 , the second position  12 , and the third position  13 . The zoom mechanism comprises a linear actuator device  15 , and a stop actuator device  16 . The stop actuator device  16  comprises a switchably configurable material. 
     The switchably configurable material switches selectively between a first configuration and a second configuration. Switched into the first configuration, the motion of the movable lens  39  load is unconstrained between the first position  11  and the second position  12 . In the second configuration, the motion of the movable lens is stopped, at least temporarily, in the third position  13 . 
     The movable lens  39  comprises a load, which is positioned, selectively, by the linear actuator (e.g., TULA)  15  of an associated linear positioning system. The TULA  15  is operable for moving the moveable lens  39  into position  11 , position  12  and position  13 , which are disposed over an axis of translational operation of the TULA  15  within the optical assembly  30 . 
     The first lens  37  gathers incident light, which it focuses into the optical assembly  30  along its longitudinal axis. The focused light is refocused by the movable lens  39  onto the ocular lens  38 . The ocular lens  38  further refocuses the light onto the image detector  402 . The image detector  402  may comprise a charge coupled device (CCD), complementary metal oxide semiconductor (CMOS), or photodiode (PD) array to allow capture of images scanned by the optical apparatus. 
       FIG. 3A  depicts the movable lens  39  in a temporally initial location corresponding to the first position  11  proximate to the ocular lens  38 , in which the optical assembly is configured operably for providing the ER zoom focus range. 
     In  FIG. 3B , the stop actuator  16  is reconfigured into a deactivated configuration, in which the TULA  15  moves the movable lens  39  freely, without constraint by the stop actuator  16 , into the second position  12  proximate to the first lens  39  in which the optical assembly is configured operably for providing the HD focus range. 
       FIG. 3C  depicts the stop actuator  16  in an engaged configuration, in which a hard stop  33  is effectuated to stop the movable lens  39  in the intermediate position  13 . The hard stop  33  is achieved with sufficient precision repeatedly, without associated intermediate position indicating means, so as to configure the optical assembly for providing the SR focus range. The optical assembly  30  may be operable for providing zoom focus functionality in an associated optical apparatus, such as a scanner. 
     Example Optical Apparatus 
       FIG. 4  depicts an example optical apparatus  40 , according to an example embodiment. The optical apparatus  40  may comprise a scanner. The scanner may be operable for scanning (gathering, capturing, imaging) documents and/or other two dimensional (2D) arrays of graphic data such as Han Xin, QR, and/or dot code patterns, and UPC, PDF-417 (Portable Document File with four vertical bar symbols disposed over 17 horizontal spaces) and other bar code patterns (“barcodes”). 
     The optical apparatus  40  comprises an optics system  41  with multiple lens components. The optics system  41  may also comprise other optical components, such as one or more prisms, mirrors and/or filters. 
     Among its multiple lens components, the optics system  41  comprises the first lens  37 , the ocular lens  38  and the movable lens  39  of the zoom optical assembly  30 . The movement and stops of the movable lens  39  are effectuated, respectively, by the linear actuator  15  and the stop actuator  16  of the linear positioning system  10 . 
     An example embodiment may be implemented in which the selectively configurable material of the stop actuator  16  comprises an electroactive polymer (EAP), with functional electrostrictive properties. Example embodiments may also be implemented in which the selectively configurable material comprises a shape-memory alloy (SMA). The SMA may be fabricated into a functional wire-based structure or a formed structure, which may be operable as a mechanical gate, detent, or arrester. 
     In an example embodiment, one or more features of the optical apparatus  40  may be implemented as described in the incorporated reference: U.S. Pat. Appl. Pub. No. 2014/0084068 by Gillet, et al. 
     An example embodiment may be implemented in which the scanner  40  comprises a light source  401 , the image sensor  402 , an aperture controller  403 , a range finder  404 , one or more processors  406  (e.g., microprocessor or microcontroller), one or more memory (and/or other data storage) units  407 , input/output (I/O) devices  408 , an interface  409 , and at least one power supply  409 . The scanner  40  may also have a bus  405 , which provides for the exchange of data signals between its other components. The bus  405  also allows for the power supply  409  to power the other components of the scanner  40 . 
     The light source  401  comprises a laser, light emitting diode (LED), or another light emitter and is operable for illuminating barcodes, other symbols and data arrays, documents and other scan targets. The aperture controller  403  may comprises an iris or other device for setting a level of collimation for light gathered by the first lens for admission into the optics system  41 . The range finder  404  may comprise radar, LIDAR (or other laser-related), or sonar related means, for determining a distance from the scanner  40  to a target scan object. 
     The one or more processors  405  may be used for running program applications associated with the scanner  40 . The one or more memory units  407  may comprise any non-transitory computer readable storage medium, including random-access memory (RAM), read-only memory (ROM), any combination of volatile and non-volatile memory, and/or drive devices (e.g., hard drives and/or flash devices). The non-transitory computer readable storage media comprise instructions tangibly stored therewith, which when executed by the processor(s)  405 , control processes for functions by which the scanner  40  is operable. The processes may comprise a method for adjusting a focus range of the zoom optical assembly  30 . 
     The I/O devices  408  may comprise triggers for starting and stopping the scanner  40  and controlling the zoom optical system  30 , including the linear positioning system  10 . The triggers may also initiate or control other functions of the scanner  40 . The interface  409  may comprise means for effectuating network interactions and/or communicative coupling, via wireless and/or wireline means, with an external computer  499  and with visual displays, audio transducers, and communication devices. The power supply  409  may comprise a battery and/or means for coupling to an external power source. 
     The scanner  40  may be implemented in a mobile, portable and/or handheld unit, a fixed or vehicle-mounted unit, a universal or other barcode reader. Additionally or alternatively, the scanner  40  may be implemented in a portable data terminal (PDT), mobile phones, smart phones, tablet computers, laptop computers, “Ultrabooks™,” personal digital assistants (PDAs), vehicle-based computers, etc. 
       FIG. 5A  and  FIG. 5B  each depict an example formed SMA stop actuator device  50  in respective stop-engaged and disengaged configurations  51  and  52 , according to an example embodiment. The SMA device  50  comprises a gate component (“gate”)  55 , which is affixed (“anchored”) at a first end to a fixed, rigid supporting, anchoring or foundation component (“bulkhead”)  59 . 
     The gate  55  comprises the switchably configurable SMA based material of the stop actuator device  50  and represents the dimorphic component (e.g., dimorphic component  26 ;  FIG. 2 ) thereof. The rigid bulkhead  59  restrains the first end of the gate  55  from moving. A second end of the gate  55 , opposite from the rigidly anchored first end, is operably moveable between a first position and a second position. 
     A switching mechanism (e.g.,  25 ;  FIG. 2 ) of the stop actuator is operable as an intermediate position selector  21  and as a motion limit selector (e.g., respectively:  21 ,  29 ;  FIG. 2 ). The stop actuator  50  comprises the switching mechanism and a dimorphic component (e.g.,  26 ;  FIG. 2 ). The dimorphic component  26  comprises the switchably configurable SMA material. The switching mechanism (e.g.,  25 ;  FIG. 2 ) of the stop actuator  50  is operable as an intermediate position selector  21  and as a motion limit selector  29 . 
     With the motion limit selector operable, the configurable material gate  55  is switched into a ‘disengage’ configuration. Thus, the stop actuator  50  is disengaged and freely allows a load (e.g.,  19 ;  FIG. 1 ,  FIG. 2 ) to move in either direction, unconstrained, between its limits of motion (e.g., first and second positions  11 ,  12 ;  FIG. 1 ). 
     With the intermediate position selector operable, the configurable material gate  55  is switched into an ‘engage’ configuration. Thus, the stop actuator  50  is engaged and is operable for stopping the load in the intermediate position. 
     Switching the dimorphic SMA material of the gate  55  between the engage configuration and the disengage configuration of the stop actuator  50  relates to selectively changing its shape between respective corresponding contours. With the SMA material of the gate  55 , the switching mechanism of the stop actuator  50  is operable for selectively changing the shape of the dimorphic SMA material between a native, initial and/or non-deformed contour and a deformed contour by means of a thermomechanical mechanism. 
       FIG. 5A  depicts the shape of the gate  55  in conformation with the first operational configuration of its SMA material, in which the stop actuator  50  has assumed an operably ‘engaged’ state  51 . 
       FIG. 5B  depicts the shape of the gate  55  in conformation with the first operational configuration of its SMA material, in which the stop actuator  50  has assumed an operably ‘disengaged’ state  51 . 
       FIG. 6A  and  FIG. 6B  each depict an example wire SMA stop actuator device  60  in respective stop-engaged and disengaged configurations  61  and  62 , according to an example embodiment. The SMA device  60  comprises a wire like gate component (“gate”)  65 , which is affixed (“anchored”) at a first end to a fixed, rigid supporting, anchoring or foundation component (“bulkhead”)  69 . A significant portion of the wire gate  65  may comprise a coil configuration, into which the wire material is coiled. A post  68  may function with the bulkhead  68  to support a portion of the gate  65 . 
     The gate  65  comprises a wire form (e.g., including the coiled portion) of the switchably configurable SMA based material and represents the dimorphic component (e.g., dimorphic component  26 ;  FIG. 2 ) thereof. The rigid bulkhead  69  and the post  68  restrain the first end of the wire SMA gate from moving. A second end of the wire SMA gate  65 , opposite from the rigidly anchored first end, is operably moveable between a first position and a second position. 
     A switching mechanism (e.g., switching mechanism  25 ;  FIG. 2 ) of the stop actuator is operable as an intermediate position selector and as a motion limit selector (e.g., respectively:  21 ,  29 ;  FIG. 2 ). The stop actuator  60  comprises the switching mechanism and a dimorphic component, which comprises the SMA wire gate  55 . The dimorphic component  26  comprises the switchably configurable material. The switching mechanism of the stop actuator  65  is operable as the intermediate position selector and as the motion limit selector. 
     With the motion limit selector operable, the configurable material gate  65  is switched into a ‘disengage’ configuration (e.g.,  27 ). Thus, the stop actuator  50  is disengaged and freely allows a load (e.g.,  19 ;  FIG. 1 ,  FIG. 2 ) to move in either direction, unconstrained, between its limits of motion (e.g., first and second positions  11 ,  12 ;  FIG. 1 ). 
     With the intermediate position selector operable, the configurable SMA wire material gate  65  is switched into an ‘engage’ configuration. Thus, the stop actuator  60  is engaged and is operable for stopping the load in the intermediate position. 
     Switching the dimorphic SMA material of the gate  65  between the engage configuration and the disengage configuration of the stop actuator  60  relates to selectively changing its shape between respective corresponding contours. 
     With the SMA wire material of the gate  65 , the switching mechanism of the stop actuator  60  is operable for selectively changing the shape of the dimorphic SMA material between a native, initial and/or non-deformed contour and a deformed contour by means of a thermomechanical mechanism. 
       FIG. 6A  depicts the shape of the gate  65  in conformation with the first operational configuration of its SMA material, in which the stop actuator  50  has assumed an operably ‘engaged’ state  61 . 
       FIG. 6B  depicts the shape of the gate  65  in conformation with the first operational configuration of its SMA material, in which the stop actuator  60  has assumed an operably ‘disengaged’ state  61 . 
       FIG. 7A  and  FIG. 7B  each depict an example EAP stop actuator device  70  in respective stop-engaged and disengaged configurations  71  and  72 , according to an example embodiment. The stop actuator  70  comprises an EAP gate component (“gate”)  75 , which is affixed (“anchored”) at a first end to a fixed, rigid anchoring, supporting or foundation component (“bulkhead”)  79 . 
     The gate  75  comprises an electrostrictive polymer, fabricated into a switchably configurable EAP based dimorphic component (e.g., dimorphic component  26 ;  FIG. 2 ) thereof. The rigid bulkhead  79  restrain the first end of the EAP gate  75  from moving. A second end of the EAP gate  75 , opposite from the rigidly anchored first end, is operably moveable between a first position and a second position. 
     A switching mechanism (e.g., switching mechanism  25 ;  FIG. 2 ) of the stop actuator is operable as an intermediate position selector and as a motion limit selector (e.g., respectively:  21 ,  29 ;  FIG. 2 ). The stop actuator  70  comprises the switching mechanism and a dimorphic component, which comprises the EAP gate  75 . The dimorphic component (e.g.,  26 ;  FIG. 2 ) comprises the electrostrictive switchably configurable polymer material. The switching mechanism (e.g.,  25 ) of the stop actuator  75  is operable as the intermediate position selector and as the motion limit selector. 
     With the motion limit selector operable, the configurable EAP material gate  75  is switched into a ‘disengage’ configuration (e.g.,  27 ). Thus, the stop actuator  70  is disengaged and freely allows a load (e.g.,  19 ;  FIG. 1 ,  FIG. 2 ) to move in either direction, unconstrained, between its limits of motion (e.g., first and second positions  11 ,  12 ;  FIG. 1 ). 
     With the intermediate position selector operable, the configurable EAP material gate  75  is switched into an ‘engage’ configuration. Thus, the stop actuator  70  is engaged and is operable for stopping the load in the intermediate position. 
     Switching the dimorphic SMA material of the gate  75  between the engage configuration and the disengage configuration of the stop actuator  70  relates to selectively changing its shape between respective corresponding contours. 
     With the electrostrictive EAP material of the gate  75 , the switching mechanism of the stop actuator  70  is operable for selectively changing the shape of the dimorphic EAP material between a relaxed contour and a strained contour by varying an electrostatic field in which the dimorphic EAP component is disposed. An example embodiment may be implemented in which the electrostatic field is varied by a piezoelectric mechanism. 
       FIG. 7A  depicts the shape of the gate  75  in conformation with the first operational configuration of its EAP material, in which the stop actuator  50  has assumed an operably ‘engaged’ state  71 , corresponding to the relaxed contour state of the dimorphic component. 
       FIG. 7B  depicts the shape of the gate  75  in conformation with the first operational configuration of its SMA material, in which the stop actuator  60  has assumed an operably ‘disengaged’ state  72 , corresponding to the strained contour state of the dimorphic component. 
     Example N-Position Linear Positioning System 
       FIG. 8  depicts an example N-position linear positioning system  80 , according to an embodiment of the present invention. A portion of the N-position linear positioning system  80  may comprise, analogize or be represented by one or more features described above with reference to  FIG. 1  and  FIG. 2 . 
     The linear positioning system  80  is operable for moving a load  89 , such as a movable lens in an optical zoom lens assembly, over the linear axis of motion  14 . The linear positioning system  80  comprises a linear actuator component  85 . The linear actuator  85  is operable, controllably, for moving the load  89  into a plurality of positions disposed over the linear axis  14 , which relates to a motion of the load  89 . The plurality of positions comprises a first position  11  and a second position  12 . 
     The first position  11  is disposed at the first end of the linear axis  14  and corresponding to a limit of the motion of the load  89  in a first direction. The second position  12  is disposed at a second end, opposite to the first end, of the linear axis  14  and corresponds to a limit of the motion of the load  89  in a second direction, opposite to the first direction of motion. The plurality of positions also comprises a third position  13  disposed along the linear axis at a first intermediate point between the first position  11  and the second position  12 . 
     Further, the plurality of positions also comprises at least one additional intermediate position  87 . The at least one additional intermediate position  87  is disposed along the linear axis  14  at one or more respective intermediate points between the third position  13  and the first position  11 , or between the third position  13  and the second position  12 . Thus, the plurality of positions may comprise a total number N of intermediate positions, in which ‘N’ comprises a positive whole number greater than or equal to one (1). 
     The stop actuator component  16  comprises the switchably configurable material. The configurable material switches, selectively, between the first disengaged configuration and the second engaged configuration. In the disengaged configuration, the motion of the load  89  is unconstrained between the first position  11  and the second position  12 . In the engaged (second) configuration, the stop actuator  16  is operable for a stopping the motion of the load  89  in the at least third position, where the load  19  remains while the stop actuator  16  is operably engaged. 
     The linear positioning system  80  also comprises at least one additional stop actuator component  861 , which corresponds respectively to the at least one additional position  87 . Thus, the linear positioning system  80  may comprise a total number of stop actuator components equal to the respective number N of intermediate positions. 
     Like the stop actuator  16 , the stop actuator  861  comprises the switchably configurable material and is operable in the second configuration thereof for stopping the motion of the load  89  in the at least one additional position  87  corresponding respectively thereto. 
     Like the stop actuator  16 , the stop actuator component  861  comprises the switchably configurable EAP or SMA material. The configurable material switches, selectively, between the first disengaged configuration and the second engaged configuration. In the disengaged configuration, the motion of the load  89  is unconstrained between the first position  11  and the second position  12 . In the engaged configuration, the stop actuator  861  is operable for a stopping the motion of the load  89  in the at least one additional position  87 , where the load  89  remains while the stop actuator  861  is operably engaged. 
     The linear actuator component  85  may comprise a TULA device. The switchably configurable material of the stop actuators  861  and  16  may the EAP composition or the SMA composition. The form of the SMA material may be fabricated as the formed gate structure, or as the wire structure. 
     In an example embodiment, the load  89  comprises a movable lens in a zoom focus element of an optical apparatus such as a scanner. The zoom focus element is operable selectively over the SR, the ER, and the HD focus range, as well as at least one additional range. The zoom focus element comprises the first lens, fixed in proximity to the second position, and the second sensor side lens, fixed in proximity to the first position. The position in which the movable lens load  89  is stopped corresponds to the focus range selected, over which the zoom focus is operable. 
     For example, upon the stop of the movable lens load  89  in the first position  11 , the zoom element is operable in the ER. Upon the stop of the movable lens in the second position  12 , the zoom element is operable in the HD focus range. Upon the stopping the motion of the movable lens  89  in the intermediate position  13 , the zoom element is operable in the SR focus range. 
     Upon the stopping the motion of the movable lens  89  in the at least one intermediate position  87 , the zoom element is operable in the at least one additional focus range. The stop actuators  861  and  16  are operable for stopping the movable lens in the intermediate positions  87  and  13 , respectively, with a level of precision sufficient for use in repeatably accurate and reliable optical scan operations, without cost and/or complexity associated with alternative use of intermediate position indicating means. 
     The linear positioning system  80  may comprise one or more additional stop actuator components and the plurality of positions may comprise one or more respectively corresponding intermediate positions along the linear axis  14 . The further additional intermediate positions are disposed between the third position and either the first position, or the second position. Each of the additional stop actuator components comprises one of the switchably configurable materials, and each is operable in its engaged configuration for stopping the motion of the load  89  at the respectively corresponding additional position. 
     An example embodiment may be implemented, alternatively, with a single stop actuator. For example, the stop actuator  16  may be moved from the first position  11  by a stop actuator linear positioning system  88 . The stop actuator linear positioning system  88  may also comprise a TULA. 
       FIG. 9  depicts a flowchart for an example linear positioning process  90 , according to an embodiment of the present invention. The process  90  is used for positioning a moveable lens for selecting a variety of focal ranges available from a zoom focus assembly in an optical apparatus such as a scanner. 
     In a step  91 , a linear actuator such as a TULA is activated for impelling a motion of a movable lens over a linear translational axis between first and second positions. The first and second positions are disposed at opposite ends of the axis and correspond to respective limits of the motion of the lens in opposite directions. 
     With the movable lens positioned in the first position, the zoom focus assembly provides an extended focus range (ER). With the movable lens positioned in the second position, the zoom focus assembly provides an HD. With the movable lens positioned in the intermediate position between the first and second positions, the zoom focus assembly provides an SR focus range. 
     In a step  92 , it is determined whether the SR range is being selected. 
     If the SR focal range is not selected, then in a step  93 , a stop actuator is disengaged and the movable lens is moved freely by the TULA, unconstrained from the first position to the second position, from the second position to the first position, or from an intermediate position to either the first or the second positions. 
     If the SR range selected, then in a step  94 , the stop actuator is engaged for positioning the movable lens in a selected intermediate position between the first and the second positions. The selected SR focus range provides both near-field and far-field reading high-density bar codes, and/or over a range of heightened definition, relative to the HD or the ER ranges. 
     Thus, an example embodiment is described in relation to a method for adjusting a focus range of an optical apparatus such as a scanner. The method comprises activating a linear actuator operable for impelling a motion of a movable lens of the optical apparatus over a linear translational axis between a first position on the axis and a second position opposite therefrom. The first and the second positions each comprise limits of the motion of the movable lens in respective opposite directions over the axis. 
     The method also comprises selectively disengaging a stop actuator, in which the motion of the load is unconstrained between the first the second positions. Positioning the movable lens in the second position corresponds to operating the scanner in the HD focus range. Positioning the movable lens in the first position corresponds to operating the scanner in the ER focus range. 
     Further, the method comprises selectively engaging the stop actuator. The engaged stop actuator is operable for positioning the movable lens in at least an intermediate third position disposed along the axis between the first and the second positions. Positioning the movable lens in the intermediate position corresponds to operating the scanner in an SR focus range. 
     The switchably configurable material may comprise a dimorphic component of the stop actuator. The dimorphic component comprises a first shape corresponding to the disengaging step, and a second shape corresponding to the engaging step. The disengaging step and the engaging step respectively comprise switching the dimorphic component selectively between the corresponding first shape and the second shape. 
     The switchably configurable material may comprise an EAP. The EAP may comprise an electostrictive polymer. The selective switching of the EAP may relate to varying an electrostatic field in proximity to the dimorphic component using a piezoelectric mechanism. 
     Alternatively, the switchably configurable material may comprise an SMA. Selectively switching the SMA may relate to adjusting a deformation in a configuration of the dimorphic component using a thermomechanical mechanism. 
     Example embodiments of the present invention are thus described in relation to a system is disclosed for positioning a load in of multiple positions disposed over a linear axis. A linear actuator moves the load into each of the positions. A first position is at an end of the movement, with a second position opposite. A third position is intermediate between the first and the second positions. A stop actuator is made of a configurable material switchable selectively between an engaged configuration, in which the load is positioned in the at least third position, and a disengaged configuration, in which the load is freely movable between the first and the second positions. 
     To supplement the present disclosure, this application incorporates entirely by reference the following commonly assigned patents, patent application publications, and patent applications:
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     In the specification and/or figures, example embodiments of the invention have been described in relation to a process is described for scanning a scan target related to an electronic display or a print based graphic medium. An image of the scan target is captured over an exposure duration and with an illumination activated at a fixed lighting intensity level and for a set illumination duration. The set illumination duration corresponds to a mere fraction of the exposure duration. The illumination deactivates upon expiration of the illumination duration. A quality related characteristic of the captured image is evaluated relative to a target quality metric. 
     The present invention is not limited to such example embodiments. Embodiments of the present invention also relate to equivalents of the examples described herein. The use of the term “and/or” includes any and all combinations of one or more of the associated listed items. The figures are schematic representations and so are not necessarily drawn to scale. Unless otherwise noted, specific terms have been used in a generic and descriptive sense and not for purposes of limitation. 
     An example embodiment of the present invention relates to a system for positioning a load in of multiple positions disposed over a linear axis. A linear actuator moves the load into each of the positions. A first position is at an end of the movement, with a second position opposite. A third position is intermediate between the first and the second positions. A stop actuator is made of a configurable material switchable selectively between an engaged configuration, in which the load is positioned in the at least third position, and a disengaged configuration, in which the load is freely movable between the first and the second positions.