Abstract:
Embodiments of the invention provide a mold for forming a lens including a first core coupled with a first core hole of a first mold, and a second core coupled with a second core hole of a second mold to face the first core. In accordance with at least one embodiment, the first core and the second core are made of a material having a coefficient of thermal expansion larger than that of the first mold and the second mold, and outer diameters of the first core and the second core are each formed to be smaller than diameters of the first core hole and the second core hole.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of and priority under 35 U.S.C. §119 to Korean Patent Application No. KR 10-2013-0148631, entitled “System for Correcting Off-Set and Controlling Method Thereof,” filed on Dec. 2, 2013, which is hereby incorporated by reference in its entirety into this application. 
       BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an offset correction system and a method for controlling the same. 
         [0004]    2. Description of the Related Art 
         [0005]    A digital photographing apparatus may process a received image via a digital signal processor via an imaging device, compress the image to generate an image file, and store the image file in a memory. 
         [0006]    Although the digital photographing apparatus may display and show the image of the image file, which is received via the imaging device or stored in a storage medium, on a display device such as a liquid crystal display (LCD), the digital photographing apparatus such as a camera may shake due to user handshake, while a user captures a desired image. Accordingly, due to shake, an image input via an imaging device may shake, resulting in photography failure. 
         [0007]    Accordingly, in order to prevent photography failure due to handshake, when handshake occurs, a correcting process, as described, for example, in KR 2012-0073136, is performed via a handshake correction function (optical image stabilization: OIS) of detecting an angular velocity of a camera via a gyro sensor installed in a camera, calculating a driving distance of a camera lens based on the angular velocity, moving the lens by as much as the distance via a voice coil motor (VCM), and then, feeding back a location of the lens from an output signal of a hall sensor. 
         [0008]    However, a frequency of the signal output from the hall sensor is 1 Hz to 30 Hz and belongs to a low frequency band, and the size of the output signal is small. Thus, it is necessary to amplify the output signal through an amplifier. In this regard, when direct current (DC) offset occurs in the output signal, accuracy of a handshake correction function based on the output signal may be degraded due to deterioration of the hall sensor. 
       SUMMARY 
       [0009]    Accordingly, embodiments of the present invention provide an offset correction system and a method for controlling the same, which applies an offset correction voltage to an internal terminal of an operational amplifier (OP-AMP) for amplifying a signal detected by a hall sensor with predetermined gain, when direct current (DC) offset occurs in the detected signal, thereby minimizing possibility of change in an output signal of the OP-AMP due to noise generated in the offset correction voltage. 
         [0010]    According to an embodiment of the present invention, there is provided an offset correction system including a location sensor for outputting a signal about location information of a lens, a digital signal processor for determining whether direct current (DC) offset occurs from the output signal and generating a digital control signal for correction of the DC offset when the DC offset occurs, and an amplifier for amplifying the signal output by the location sensor via an operational amplifier (OP-AMP) and applying an offset correction voltage corresponding to the digital control signal directly to an internal terminal of the OP-AMP when the DC offset occurs. 
         [0011]    In accordance with at least one embodiment, the location sensor includes a hall sensor for outputting a first voltage signal V 1  and a second voltage signal V 2 , corresponding to a location of the lens. 
         [0012]    In accordance with at least one embodiment, the OP-AMP includes at least one P-channel metal oxide semiconductor (PMOS) and N-channel metal oxide semiconductor (NMOS). 
         [0013]    In accordance with at least one embodiment, the internal terminal of the OP-AMP is a bulk terminal of the at least one PMOS, and the PMOS has a gate terminal that is electrically connected to a non-inverting terminal or inverting terminal of the OP-AMP. 
         [0014]    In accordance with at least one embodiment, the PMOS has a threshold voltage that varies according to the offset correction voltage input to the bulk terminal of the PMOS. 
         [0015]    In accordance with at least one embodiment, the PMOS also has drain current that varies according to the threshold voltage of the PMOS. 
         [0016]    In accordance with at least one embodiment, the NMOS has a bulk terminal that is electrically connected to a ground terminal. 
         [0017]    In accordance with at least one embodiment, the digital signal processor generates the digital control signal corresponding to the offset correction voltage for correction of the DC offset, when the DC offset occurs between the first voltage signal V 1  and the second voltage signal V 2 . 
         [0018]    In accordance with at least one embodiment, the offset correction system further includes a second signal converter for converting the digital control signal into an offset correction voltage in an analog form and applying the offset correction voltage to the amplifier. 
         [0019]    In accordance with at least one embodiment, the offset correction system further includes a first signal converter for converting the signal output from the amplifier in a digital signal form. 
         [0020]    In accordance with at least one embodiment, the amplifier includes an OP-AMP having an internal terminal to which the offset correction voltage is directly applied, a first resistor electrically connected to each of a non-inverting terminal and an inverting terminal of the OP-AMP, and a second resistor for electrically connecting the inverting terminal and an output terminal of the OP-AMP. 
         [0021]    In accordance with at least one embodiment, the OP-AMP includes a second PMOS having a gate terminal that is electrically connected to the inverting terminal and a third PMOS having a gate terminal that is electrically connected to the non-inverting terminal. 
         [0022]    In accordance with at least one embodiment, the offset correction voltage is applied directly to a bulk terminal of the second PMOS and third PMOS. 
         [0023]    In accordance with at least one embodiment, the OP-AMP includes a first PMOS for controlling input current I D  using a bias voltage input to a gate terminal, an offset correction circuit to which the offset correction voltage is applied, a current mirror module for equalizing amounts of currents I D1  and I D2  output from the offset correction module, a fourth PMOS for controlling output current I P  using a bias voltage input to a gate terminal, and a third NMOS for amplifying the output current I P  with predetermined gain to generate an output voltage V O . 
         [0024]    In accordance with at least one embodiment, the offset correction circuit includes a second PMOS having a gate terminal electrically connected to the inverting terminal of the OP-AMP and a third PMOS having a gate terminal electrically connected to the non-inverting terminal. 
         [0025]    In accordance with at least one embodiment, the offset correction circuit applies the offset correction voltage directly to a bulk terminal of the second PMOS and third PMOS. 
         [0026]    According to another embodiment of the present invention, there is provided a method for controlling an offset correction system, the method including detecting a signal about location information of a lens, amplifying the detected signal via an operational amplifier (OP-AMP), determining whether direct current (DC) offset occurs from the detected signal, and correcting offset by generating an offset correction voltage and applying the offset correction voltage to an internal terminal of the OP-AMP, when the DC offset occurs. 
         [0027]    In accordance with at least one embodiment, the correcting step includes generating a digital control signal for correction of the DC offset, when the DC offset occurs, converting the digital control signal into the offset correction voltage, corresponding to the digital control signal, in an analog form, and applying the offset correction voltage to an internal terminal of the OP-AMP. 
         [0028]    In accordance with at least one embodiment, the internal terminal of the OP-AMP is a bulk terminal of the at least one PMOS, and the PMOS has a gate terminal that is electrically connected to a non-inverting terminal or inverting terminal of the OP-AMP. 
         [0029]    In accordance with at least one embodiment, the method further includes the step of converting the amplified signal in a digital signal form after the amplifying step. 
         [0030]    Various objects, advantages and features of the invention will become apparent from the following description of embodiments with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0031]    These and other features, aspects, and advantages of the invention are better understood with regard to the following Detailed Description, appended Claims, and accompanying Figures. It is to be noted, however, that the Figures illustrate only various embodiments of the invention and are therefore not to be considered limiting of the invention&#39;s scope as it may include other effective embodiments as well. 
           [0032]      FIG. 1  is a block diagram illustrating an offset correction system, in accordance with an embodiment of the present invention. 
           [0033]      FIG. 2  is a flowchart illustrating a method for controlling an offset correction, in accordance with an embodiment of the present invention. 
           [0034]      FIG. 3  is a circuit diagram illustrating an amplifier of an offset correction system, in accordance with an embodiment of the present invention. 
           [0035]      FIG. 4  is a diagram illustrating an equivalent circuit diagram of an operational amplifier (OP-AMP) of an amplifier, in accordance with an embodiment of the present invention. 
           [0036]      FIG. 5  is a diagram illustrating the structure of a PMOS and an NMOS included in an OP-AMP of an amplifier, in accordance with an embodiment of the present invention. 
           [0037]      FIGS. 6(   a )-( c ) illustrate influence of an output voltage of an OP-AMP from an offset correction voltage, in accordance with embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0038]    Advantages and features of the present invention and methods of accomplishing the same will be apparent by referring to embodiments described below in detail in connection with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. The embodiments are provided only for completing the disclosure of the present invention and for fully representing the scope of the present invention to those skilled in the art. 
         [0039]    For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the discussion of the described embodiments of the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. Like reference numerals refer to like elements throughout the specification. 
         [0040]    Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Hereinafter, driving of a lens will be described based on one axis (X-axis or Y axis) of the lens, which may be applied to another axis (X-axis or Y axis) in the same way. In addition, a P-channel metal oxide semiconductor (PMOS) and an N-channel metal oxide semiconductor (NMOS) refer to P-type and N-type metal-oxide semiconductor field effect transistor (MOSFET) transistors, respectively. 
         [0041]      FIG. 1  is a block diagram illustrating an offset correction system, in accordance with an embodiment of the present invention.  FIG. 2  is a flowchart illustrating a method for controlling an offset correction, in accordance with an embodiment of the present invention. In accordance with at least one embodiment, as shown in  FIGS. 1 and 2 , the offset correction system  10  includes a location sensor  100 , an amplifier  200 , a first signal converter  300 , a digital signal processor  400 , a second signal converter  800 , a motor driver  500 , a voice coil motor (VCM)  600 , and a lens  700 . 
         [0042]    In accordance with at least one embodiment, the location sensor  100  includes a hall sensor  110  (refer to  FIG. 3 ) for detection of a current location of the lens  700  using a hall effect, whereby a voltage varies according to intensity of a magnetic field, and an angular velocity sensor (not shown) for detection of an angular velocity of movement due to a handshake of a photographer, and detects location information of the lens  700  using the hall sensor  110  and the angular velocity sensor (not shown) (S 100 ). Here, the hall sensor  100  outputs a first voltage signal V 1  and a second voltage signal V 2 , which correspond to the location of the lens  700  (S 100 ). Here, the first voltage signal V 1  and the second voltage signal V 2  may have, but are not limited to, a sine wave form. 
         [0043]    As further shown in  FIGS. 1 and 2 , the amplifier  200 , according to at least one embodiment, includes an operational amplifier (OP-AMP)  210  (refer to  FIG. 3 ) and amplifies voltage signals V 1  and V 2  corresponding to a current location of the lens  700 , detected by the hall sensor  110 , via the OP-AMP  210  (S 110 ). In accordance with one embodiment, the amplifier  200  is a low noise amplifier (LNA). The first signal converter  300  converts the amplified voltage value into a digital value and is, for example, an analog digital converter. 
         [0044]    In addition, with regard to the amplifier  200 , when DC offset between the first and second voltage signals V 1  and V 2  occurs, an offset correction voltage V DAC  for correction of the DC offset is applied directly to an internal terminal of the OP-AMP  210 , which will be described in more detail. 
         [0045]    In accordance with at least one embodiment, the digital signal processor  400  generates a digital control signal for control of a driving range of the lens  700  based on the location information of the lens  700 , detected from the location sensor  100 . The digital control signal is, for example, composed of 10 bits. Among the 10 bits, a most significant bit (MSB) is a sign bit and refers to a driving direction of the lens  700 , and the remaining bits refer to the amount of driving current of the VCM  600 , corresponding to a moving distance of the lens  700 . 
         [0046]    In addition, the motor driver  500  generates a driving voltage of the VCM  600 , for driving the lens  700 , based on the digital control signal input from the first signal converter  300 , and drives the VCM  600  using the driving voltage. Here, the digital signal processor  400  generates the digital control signal via proportion integral derivative (PID) control. 
         [0047]    In addition, the digital signal processor  400  determines whether DC offset occurs between the first and second voltage signals V 1  and V 2  output from the hall sensor  110  (S 120 ) and generates a digital control signal for correction of the DC offset, when the DC offset occurs (S 130 ). The second signal converter  800  converts the digital control signal into an offset correction voltage VDAC in an analog form (S 140 ) and applies the offset correction voltage VDAC to an internal terminal of the amplifier  200  (S 150 ). 
         [0048]    As described above, according to embodiments of the present invention, an offset correction system determines whether DC offset occurs in an output signal of a hall sensor, generates a digital control signal for correction of the DC offset, when the DC offset occurs, applying an offset correction voltage corresponding to the digital control signal directly to an internal terminal of an OP-AMP, and correct the DC offset in real time, thereby more stably obtaining accuracy for correction of image shake due to the handshake of a photographer based on location information detected from the hall sensor while the lens is driven. 
         [0049]    Hereinafter, with reference to  FIGS. 3 to 5 , correction of DC offset by applying an offset correction voltage to an amplifier of an offset correction system according to an embodiment of the present invention will be described in more detail. 
         [0050]      FIG. 3  is a circuit diagram illustrating an amplifier  200  of an offset correction system, in accordance with an embodiment of the present invention.  FIG. 4  is a diagram illustrating an equivalent circuit diagram of the OP-AMP  210  of the amplifier  200 , in accordance with an embodiment of the present invention.  FIG. 5  is a diagram illustrating the structure of a PMOS and an NMOS included in the OP-AMP  210  of the amplifier  200 , in accordance with an embodiment of the present invention. 
         [0051]    As illustrated in  FIG. 3 , the amplifier  200 , according to an embodiment of the invention, includes the OP-AMP  210  having an internal terminal to which an offset correction voltage for correction of DC offset generated between the first and second voltage signals V 1  and V 2  output from the hall sensor  110  is directly applied, first resistors R 1  that are electrically connected to a non-inverting terminal V +  and an inverting terminal V −  of the OP-AMP  210 , respectively, and a second resistor R 2  that electrically connects the inverting terminal V −  to an output terminal V O  of the OP-AMP  210 , but is not limited to the circuit configuration. Thus, the amplifier  200  includes another circuit configuration for amplifying the first and second voltage signals V 1  and V 2  with predetermined gain. 
         [0052]    As illustrated in  FIG. 4 , the OP-AMP  210  of the amplifier  200 , in accordance with an embodiment of the invention, includes at least one PMOS and NMOS. In detail, the OP-AMP  210  includes a first PMOS  211  and a fourth PMOS  214  that control input current I D  and output current I P  using a bias voltage V bias  input to a gate terminal, an offset correction circuit  212  to which the offset correction voltage is applied, a current mirror circuit  213  for equalizing amounts of currents I D1  and I D2  output from the offset correction circuit  212 , and a third NMOS  215  for amplifying the output current I P  with predetermined gain to generate the output terminal V O . However, embodiments of the present invention are not limited thereto. Thus, the OP-AMP  210  includes another circuit configuration as long as equivalent objective is achieved. 
         [0053]    In addition, the offset correction circuit  212 , in accordance with an embodiment of the invention, includes a second PMOS  212   a  with a gate terminal that is electrically connected to the non-inverting terminal V +  of the OP-AMP  210 , and a third PMOS  212   b  with a gate terminal that is electrically connected to the inverting terminal V − . An offset correction voltage for correction of DC offset generated between the output signals V 1  and V 2  of the hall sensor  110  is applied directly to a bulk terminal  212   a   3  (refer to  FIG. 5(   a )) of a third PMOS  212   b  and the second PMOS  212   a  as an internal terminal of the OP-AMP  210 . 
         [0054]    In detail, as illustrated in  FIG. 5(   a ), the second and third PMOSs  212   a  and  212   b  of the offset correction circuit  212  are configured in such a way that a P +  region  212   a   2  (implanted with group 3 element (e.g., Indium (In), Boron (B), etc.)) is formed in an N-type substrate  212   a , (implanted with group 5 element (e.g., arsenic (As), phosphorous (P), etc.), an insulating layer  212   a   7  is formed on the N-type substrate  212   a   1 , a source terminal S  212   a   4  and a drain terminal D  212   a   6  are electrically connected to the P +  region  212   a   2 , and a gate terminal G  212   a   5  is formed on the insulating layer  212   a   7 . 
         [0055]    In addition, the bulk terminal  212   a   3 , according to an embodiment of the invention, is formed on the N-type substrate  212   a   1 , and an offset correction voltage for correction of DC offset generated between the outputs signals V 1  and V 2  of the hall sensor  110  is applied directly to the bulk terminal  212   a   3 . 
         [0056]    Thus, as shown in  FIG. 4  and Equations 1 and 2 below, when DC offset is generated between the outputs signals V 1  and V 2  of the hall sensor  110 , the digital signal processor  400  generates a digital control signal for correction of the offset, converts the digital control signal into an offset correction voltage in an analog form via the second signal converter  800 , and then applies the offset correction voltage to the bulk terminal  212   a   3  of the second and third PMOSs  212   a  and  212   b  included in the offset correction circuit  212 . 
         [0057]    In detail, an amplitude of the offset correction voltage applied to the bulk terminal  212   a   3  of the second and third PMOSs  212   a  and  212   b  is adjusted to control a voltage V SB  between the source terminal S  212   a   4  and the bulk terminal  212   a   3  to lower or enhance a threshold voltage V TH  of the second and third PMOSs  212   a  and  212   b  according to a body effect, as shown in Equation 1 below. Accordingly, as shown in Equation 2 below, amounts of drain currents I D1  and I D2  of the second and third PMOS  212   a  and  212   b  are controlled. 
         [0058]    Furthermore, when the offset correction voltage varies according to the amount of DC offset generated between the output signals V 1  and V 2  of the hall sensor  110  and is applied to the bulk terminal  212   a   3  of the second and third PMOSs  212   a  and  212   b , drain currents I D1  and I D2  of the second and third PMOS  212   a  and  212   b  vary, the drain current I D2  and a voltage (a node N 2 ) formed by a second NMOS are applied to a gate terminal of the third NMOS  215 , and the output current I P  and an output voltage V O  formed by the third NMOS  215  vary, thereby correcting the DC offset generated between the output signals V 1  and V 2  of the hall sensor  110  in real time. 
         [0059]    As illustrated in  FIG. 5(   b ), first to third NMOSs  215  of the offset correction circuit  212  are configured in such a way that a N +  region  213   b   2  (implanted with group 5 element (e.g., arsenic (As), phosphorous (P), etc.)) is formed in a P-type substrate  213   b   1  (implanted with group 3 element (e.g., Indium (In), Boron (B), etc.)), an insulating layer  213   b   7  is formed on the P-type substrate  213   b   1 , a source terminal S  213   b   4  and a drain terminal D  213   b   6  are electrically connected to the N +  region  213   b   2 , and a gate terminal G  213   b   5  is formed on insulating layer  213   b   7 . Here, a bulk terminal  213   b   3  on the P-type substrate  213   b   1  is electrically connected to a ground terminal GND. 
         [0000]        V   TH   =V   T0 +γ(√{square root over (|φ S   |+|V   SB |)}−√{square root over (φ S )}).  [Equation 1]
 
         [0060]    (V TO =substrate bias voltage, γ=body effect variable, Φ S =surface voltage variable, and V SB =voltage between source terminal and bulk terminal) 
         [0000]    
       
         
           
             
               
                 
                   
                     I 
                     D 
                   
                   = 
                   
                     
                       β 
                       2 
                     
                      
                     
                       
                         ( 
                         
                           
                             V 
                             GS 
                           
                           - 
                           
                             V 
                             TH 
                           
                         
                         ) 
                       
                       2 
                     
                   
                 
               
               
                 
                   [ 
                   
                     Equation 
                      
                     
                         
                     
                      
                     2 
                   
                   ] 
                 
               
             
           
         
       
     
         [0061]    (ID=drain current and V GS =voltage between gate terminal and source terminal) 
         [0062]    Hereinafter, correlation between an output voltage of an OP-AMP and noise generated in an offset correction voltage for correction of DC offset will be described in detail with reference to  FIGS. 6(   a )-( c ). 
         [0063]      FIG. 6(   b ) is a graph illustrating a frequency response curve between an offset correction voltage and an output voltage when an offset correction voltage is applied to a non-inverting terminal of an OP-AMP, in accordance with an embodiment of the present invention.  FIG. 6(   a ) is a circuit diagram illustrating a case in which an offset correction voltage is applied to a non-inverting terminal of an OP-AMP, in accordance with an embodiment of the present invention.  FIG. 6(   c ) is a graph illustrating a frequency response curve between an offset correction voltage and an output voltage when an offset correction voltage is applied to a bulk terminal of an OP-AMP, in accordance with an embodiment of the present invention. 
         [0064]    As illustrated in  FIG. 6(   b ), when an offset correction voltage is applied to the non-inverting terminal V +  of the OP-AMP  210 , |V O /V DAC | of a point a (f=42.79 Hz) is 19.8 (dB) and corresponds to about 9.8 times according to the frequency response curve between the offset correction voltage and the output voltage V O  of the OP-AMP. As illustrated in  FIG. 6(   a ), in order to correct DC offset generated between the output signals V 1  and V 2  of the hall sensor  110 , when the offset correction voltage is applied directly to the non-inverting terminal V +  of the OP-AMP  210 , if noise of 1 mV occurs in the offset correction voltage V DAC , noise of 10 mV occurs in the output voltage V O . Accordingly, in consideration of the real state in which an amplify gain of the amplifier  200  is set to about 200 times, a problem arises in that a significant amount of noise occurs in the output voltage V O  due to nose by the offset correction voltage. 
         [0065]    However, like the offset correction system  10  of  FIG. 6(   c ) according to an embodiment of the present invention, when an offset correction voltage is applied directly to the bulk terminal  212   a   3  of the OP-AMP  210 , |V O /V DAC | of a point b (f=42.79 Hz) is −5 (dB) and corresponds to about 0.5 times according to the frequency response curve between the offset correction voltage and the output voltage V O  of the OP-AMP  210 . When noise of 1 mV occurs in the offset correction voltage V DAC , noise of 0.5 mV occurs in the output voltage V O . Accordingly, the amount of generated noise generated in the output voltage V O  is reduced to about 1/20 compared with a case in which the offset correction voltage is applied to the non-inverting terminal V +  of the OP-AMP  210 . 
         [0066]    As described above, an offset correction system according to an embodiment of the present invention applies the offset correction voltage directly to a bulk terminal of at least one PMOS included in an offset correction module, when DC offset occurs in an output signal of a hall sensor, and thus, minimizes influence of an output signal of the OP-AMP from noise generated in the offset correction voltage, thereby achieving more effective handshake correction and ensuring the stability of a system. 
         [0067]    According to embodiments of the present invention, an offset correction system determines whether DC offset occurs in an output signal of a hall sensor, generates a digital control signal for correction of the DC offset when the DC offset occurs, and applies an offset correction voltage corresponding to the digital control signal directly to an internal terminal of an OP-AMP so as to correct the DC offset in real time, and thus, may more stably achieve high accuracy of handshake correction of an image due to handshake of a photographer when the lens is driven based on location information detected by a hall sensor. 
         [0068]    In addition, the offset correction system applies the offset correction voltage to a bulk terminal of at least one PMOS included in an offset correction module when DC offset occurs in an output signal of a hall sensor, and thus, minimize influence of an output signal of an OP-AMP from noise generated in the offset correction voltage, thereby achieving more effective handshake correction and ensuring the stability of a system. 
         [0069]    Terms used herein are provided to explain embodiments, not limiting the present invention. Throughout this specification, the singular form includes the plural form unless the context clearly indicates otherwise. When terms “comprises” and/or “comprising” used herein do not preclude existence and addition of another component, step, operation and/or device, in addition to the above-mentioned component, step, operation and/or device. 
         [0070]    Embodiments of the present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step. 
         [0071]    The terms and words used in the present specification and claims should not be interpreted as being limited to typical meanings or dictionary definitions, but should be interpreted as having meanings and concepts relevant to the technical scope of the present invention based on the rule according to which an inventor can appropriately define the concept of the term to describe the best method he or she knows for carrying out the invention. 
         [0072]    The terms “first,” “second,” “third,” “fourth,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Similarly, if a method is described herein as comprising a series of steps, the order of such steps as presented herein is not necessarily the only order in which such steps may be performed, and certain of the stated steps may possibly be omitted and/or certain other steps not described herein may possibly be added to the method. 
         [0073]    The singular forms “a,” “an,” and “the” include plural referents, unless the context clearly dictates otherwise. 
         [0074]    As used herein and in the appended claims, the words “comprise,” “has,” and “include” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps. 
         [0075]    As used herein, the terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein. The term “coupled,” as used herein, is defined as directly or indirectly connected in an electrical or non-electrical manner. Objects described herein as being “adjacent to” each other may be in physical contact with each other, in close proximity to each other, or in the same general region or area as each other, as appropriate for the context in which the phrase is used. Occurrences of the phrase “in one embodiment” herein do not necessarily all refer to the same embodiment. 
         [0076]    Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range. 
         [0077]    Although the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereupon without departing from the principle and scope of the invention. Accordingly, the scope of the present invention should be determined by the following claims and their appropriate legal equivalents.