Abstract:
A system can include an input for receiving objects having a flat shape; a capacitance sensing network comprising a plurality of capacitance sensors positioned to be proximate to the received objects; an operations section coupled to the capacitance sensing network and configured to perform predetermined operations on the objects; and a processor section coupled to receive capacitance sense values from the capacitance sensors and configured to determine the presence and features of received objects, prior to the objects being forwarded to the operations section.

Description:
This application claims the benefit of U.S. provisional patent application Ser. No. 61/700,441 filed on Sep. 13, 2012, the contents of which are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to capacitance sensing, and more particularly to capacitance sensing objects to control the processing of the objects. 
     BACKGROUND 
     Printing devices can rely on sensing sheets of paper to ensure they are properly processed. Conventional printing systems can utilize light sensors to detect the presence and/or location of a paper in a system. When the paper passes over a sensor, the light path is broken, signaling the presence of the paper. 
     Conventional printing devices are also known that utilize ultrasound for sensing paper features. In particular, an ultrasound speaker can issue a sound, and according to the attenuation of the signal, a number of sheets of paper can be determined. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a system according to an embodiment. 
         FIGS. 2A and 2B  are diagrams showing a capacitance sensing section that can be included in embodiments. 
         FIGS. 3A to 3G  are side cross sectional views of a capacitance sensing array, showing various capacitance sensing operations according to embodiments. 
         FIG. 4  is a diagram showing mutual capacitance sensing that can be included in embodiments. 
         FIG. 5  is a diagram showing self-capacitance sensing that can be included in embodiments. 
         FIGS. 6A-0  to  6 D- 1  are top plan views showing capacitance sensing of various objects according to embodiments. 
         FIGS. 7 ,  8 ,  9 ,  10  and  11  show capacitance sensing sections that are smaller than a sensed object, according to embodiments. 
         FIGS. 12A to 12C  are diagrams showing alignment detection operations that can be included in embodiments. 
         FIG. 13  is a flow diagram of a method according to an embodiment. 
         FIGS. 14A to 14C  are diagrams showing a capacitance sense operation according to an embodiment. 
         FIG. 15  is a flow diagram of a method corresponding to a sense operation like that of  FIGS. 14A to 14C . 
         FIG. 16  is a diagram showing an alignment detection operation that can be included in embodiments. 
         FIGS. 17A and 17B  are diagrams showing capacitance sense operation according to various embodiments. 
         FIGS. 18A and 18B  show a flow diagram showing a method of printing according to an embodiment. 
         FIGS. 19 and 20  are side cross sectional views of printing devices according to embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments will now be described that show systems and methods that use capacitance sensing to control the processing of objects. In some embodiments, an array of capacitance sensors can determine the presence of objects, as well as features of such objects, including object size, object alignment relative to other parts of a system, number of objects (in the event objects stack), humidity of the objects (e.g., environment of the object), and/or the presence of foreign objects. 
     In particular embodiments, objects can be sheets of a material. In a very particular embodiment, an array of capacitance sensors can determine the features of sheets of paper, as the paper is fed into, or from, various sections of a printing device. 
     Referring to  FIG. 1 , a system  100  according to an embodiment is shown in block schematic diagram. A system  100  can include an object input section  102 , a capacitance sense (cap sense) section  104 , an operations section  106 , an object output  108 , and a processing section  110 . Optionally, a system  100  can further include a second capacitance sense section  104 ′. An object input section  102  can provide flat-shaped objects to a capacitance sense section  104 . In some embodiments, an object input section  102  can take any suitable form, including a structure as basic as an opening for receiving a flat-shaped object, or can have more complex structures, including those that automatically feed objects from a storage location into a capacitance sense section  104 . In very particular embodiments, objects can be flat-shaped objects can have a length, width, and thickness, with a thickness no more than about 1/10th of the smaller length or width. 
     A capacitance sense section  104  can include an array of capacitance sensors that can sense an area containing a received object (or multiple objects). Such measures of capacitance can be provided by the capacitance sense section  104  itself, or by processing section  110 . A capacitance sense section  104  can be larger than a received object, and thus be able to sense the extents of an object in a single scan (a sampling of all sensors). Alternatively, a capacitance sense section  104  can be smaller than a received object, and thus be able to sense the extents of an object with multiple scans, as the object passes adjacent to the array of sensors, or vice versa. 
     A processing section  110  can receive or generate capacitance values from a capacitance sense section  104 , and from such values detect the presence of objects, as well as derive features of objects. Such features can include, but are not limited to: an alignment of the object; the number of objects; the size of an object; the humidity of the object; and the presence of a foreign object (i.e., an object different from those being processed). 
     An alignment section  112 - 0  can derive the alignment of an object of an object from capacitance sensor values. Such an alignment can include an orientation of the object in space as compared to a desired orientation. Such orientation can be in a lateral direction (i.e., parallel to a sensor array), as well as a vertical direction (i.e., away from or close to the sensor array). 
     A number section  112 - 1  can derive the number of objects. The number of objects can include detecting when more than one object is stacked on top of one another. Further, in some embodiments, such a sensing can determine when objects partially overlap one another, and the extent of any such overlap. 
     A size section  112 - 2  can determine a size of an object. A size of an object can include deriving its length, width, perimeter and area, as but a few examples. This can include detecting discontinuities in expected object area (i.e., holes in an object). This can also include detecting shapes of object beyond simple rectangles, ellipses, and circles. 
     A humidity section  112 - 3  can determine a humidity of an object. A humidity of an object can include an amount of moisture in an object and/or the humidity of the local processing environment. 
     A foreign object section  112 - 4  can detect the presence of a foreign object. A foreign object can be an object other than that which is to be operated on. 
     An object material section  112 - 5  can detect the material of which the object is made by referencing the detected capacitance to the capacitance of expected materials. This embodiment may implement additional sensing technologies, including sensing of both mutual and capacitance or optical or ultrasound sensing. 
     It is understood that in addition to humidity, a processing section  106  can sense any other alteration of an object that varies its capacitance, including but not limited to the presence of coating or the state of a material, as but two examples. 
     An operations section  106  can perform predetermined operations on an object that are controlled according to one or more of the features derived by processing section  110 . Operations performed by an operations section  106  can include any suitable manufacturing operations including but not limited to: printing, painting, imprinting, shaping (cutting, etching, attaching, folding), or coating. Control of an operations section  106  in response to derived features can include, but is not limited to, stopping or preventing the processing of an object, or altering the operation(s) performed on an object. 
     In very particular embodiments, an operations section  106  can be printing mechanism and objects can be sheets of paper. 
     An output section  108  can receive can receive processed objects from operations section  106 . Like input section  102 , output section  108  can take any suitable form, including a structure as simple as an opening for receiving processing objects, to more complex structures, including those that automatically feed processed objects, or perform additional operations on such objects. Operations of an output section  108  can be controlled according to features derived by processing section  110 . 
     In very particular embodiments, an output section  108  can include a collating and/or stapling mechanism for organizing printed sheets of paper. 
     Optional capacitance sensing section  104 ′ can have a structure like any of those described for  104 . However, optional capacitance sensing section  104 ′ can enable features to be derived from objects after they are processed by operations section  106 . 
       FIGS. 2A and 2B  show a capacitance sensing section  204  according to one embodiment. Referring to  FIG. 2A , a capacitance sensing section  204  can include a first array of electrodes (one such electrode shown as  214 ) separated from a second array of electrodes (one such electrode shown as  216 ). In the embodiment shown, first electrodes  214  can overlap second electrodes  216 . A capacitance sensor (one shown as  218 ) can be conceptualized as being formed at an intersection of the electrodes. An object  220  can be placed between first electrodes  214  and second electrodes  216 . 
       FIG. 2B  shows object  220  in a sensing position within capacitance sensing section  204 . Object  220  can be placed between first electrodes  214  and second electrodes  216 . The presence of the object  220  can result in a variation of the capacitance at sensor locations corresponding to the object (one shown as  218 ′). As will be described in more detail below, based on such changes in capacitance, various features of an object can be derived. In a very particular embodiment, an object  220  can be a sheet of paper. 
     While  FIGS. 2A and 2B  show electrodes having rectangular shapes that are orthogonally oriented with respect to one another, such an arrangement should not be considered limiting. Electrodes can have any suitable shape according to the object to be sensed, as well as the information to be derived. Further, as will also be shown below, a capacitance sensing section  204  can include but one array of electrodes or both arrays of electrodes measured independently (e.g., self-capacitance sensing arrangement). 
       FIGS. 3A to 3G  show capacitance sensing operations according to a particular embodiment.  FIGS. 3A to 3G  show a capacitance sensing section  304  having electrode arrays, like those of  FIGS. 2A and 2B , but in a side cross sectional view. Thus,  FIG. 3A  show first electrodes (one shown as  314 ) and a second electrode  316  (it being understood that there is an array of such second electrodes). A mutual capacitance can be sensed between first and second electrodes according to any suitable technique. 
       FIG. 3A  shows a capacitance sensing section  304  in the absence of an object. A “baseline” mutual capacitance (one shown as Cm) can exist at intersections of first and second electrodes. Such a baseline mutual capacitance can serve as a reference point. Variations from a baseline capacitance can indicate the proximity of an object. 
       FIG. 3B  shows a capacitance sensing section  304  with an object  320  for sensing. The presence of object can result in a change in the mutual capacitance between sensors. Thus, a mutual capacitance a sensor at the location of the object  320  (one shown as C1) can vary from that without the object (one shown as Cm). According to which sensors show a change in capacitance, the extents of an object can be detected. This can enable the derivation of object alignment and/or object size. Further, a capacitance can vary according to humidity, thus according to a sensed capacitance value, a humidity can also be determined. In a very particular embodiment, an object can be paper, and the mutual capacitance can increase with the presence of paper. 
       FIG. 3C  shows a capacitance sensing section  304  with multiple objects  320 - 0 ,  320 - 1  for sensing. According to some embodiments, as the number of stacked objects increases a sensed capacitance can vary correspondingly. Thus, a capacitance corresponding to multiple objects (one shown as C2) can be different from that corresponding to one object (C1) or no object. In a particular embodiment, a mutual capacitance can increase according to the number of objects. Thus, based on a capacitance value (or sampled values), a number of objects can be detected. In a very particular embodiment, objects can be paper, and the mutual capacitance can increase in an almost linear fashion as the number of sheets is increased. 
       FIG. 3D  shows a capacitance sensing section  304  with multiple objects  320 - 0 ,  320 - 1  that only partially overlap one another. Accordingly, some sensor locations can have a capacitance corresponding to multiple objects (one shown as C2), while other locations can show only one object (two shown as C1′ and C1″). Thus, based on sensed capacitance values, the extent to which objects overlap one another can be determined. 
       FIG. 3E  shows a capacitance sensing section  304  of a foreign object  322 . A foreign object  322  can cause a change in capacitance (two shown as C! and C!′) that varies from that of standard objects (i.e., objects to be processed or that have already been processed). Thus, the presence of a capacitance reading outside of an expected range can indicate a foreign object. In a very particular embodiment, objects can be paper being input for processing, and a foreign object can include a staple or other metallic item. A staple can result in a substantial increase in capacitance as compared to stacked sheets of paper. 
       FIG. 3F  shows a capacitance sensing section  304  with multiple objects  320 - 0 ,  320 - 1 , and  320 - 2 .  FIG. 3F  shows an arrangement like that of  FIG. 3C , but with three objects. It is understood that capacitance C3 can be different than that of C2 (in  FIG. 3C ), which can be different from that of C1 (in  FIG. 3B ). 
       FIG. 3G  shows a capacitance sensing section  304  with an object  320  having a feature that causes the object to be closer to one sensor than other portions of the object. A capacitance at the feature location (Cx) can be different from that of other locations (e.g., C1). Thus, capacitance values can be used to detect undesirable deformations, or to confirm irregular shapes in a vertical direction. 
     While embodiments can utilize any suitable capacitance sensing methods, embodiments with particular capacitance sensing methods will now be described. 
       FIG. 4  shows a system  400  having a capacitance sensing section like that of  FIG. 3  that utilizes mutual capacitance sensing. A system  400  can include a mutual capacitance sensing circuit  424 , a transmit de-multiplexer (deMUX)  426 , and a receive multiplexer (MUX)  428 . Sections  424 ,  426  and  428  can form part of a capacitance sensing section (e.g.,  106 ) or part of a processing section (e.g.,  110 ). 
     A mutual capacitance sensing circuit  424  can provide a transmit signal (Tx) which can be driven on one or more transmit electrodes  416  selected by deMUX  426 . Transmit signal Tx can induce a signal on receive electrodes  414  that can vary according to a mutual capacitance (e.g., Cm). Receive MUX  428  can selectively connect a receive electrode  414  to mutual capacitance sensing circuit  424  to derive a mutual capacitance value. In one embodiment, a Tx signal can be driven on a transmit electrode, and the receive electrodes can be scanned to derive sense values for a column (or row) of sensors. A next transmit electrode can then be driven to derive values for another row. This can continue until an entire array of values has been acquired. 
       FIG. 5  shows a system  500  having a capacitance sensing section that utilizes self-capacitance sensing. A system  500  can include a self-capacitance sensing circuit  530  and a sense MUX  532 . Sections  530  or  532  can form part of a capacitance sensing section (e.g.,  106 ) or part of a processing section (e.g.,  110 ). 
     A self-capacitance sensing circuit  530  can measure a self-capacitance of electrodes (one shown as  514 ), to thereby sense the presence of an object. It is understood that a self-capacitance system could also include a second array of electrodes, as shown in  FIG. 4 , where such electrodes are formed opposite to the first electrodes  514 . These electrodes could also use self-capacitance sensing to determine the presence of an object at a sensor location. In another embodiment, a second axis of self-capacitance sensors ( 516 ) may be measured by coupling the array to MUX  532 . 
     As noted above, capacitance sensing sections can sense various features of an object.  FIGS. 6A-0  to  6 D- 1  are diagrams showing various capacitance sense operations for a system that senses a flat-shaped object, such as a sheet of paper.  FIGS. 6A-0  to  6 D- 1  show a capacitance sensing array  604  and corresponding sense pattern  634  resulting from a sense operation. 
     It is understood that a capacitance sensing array  604  can be one array, or a series of scans from a smaller array taken over time (i.e., as the object passes over the array, or as the array passes over the object). That is, capacitance sensing array  604  can be larger than a sensed object or can be smaller than a sensed object. In the latter case, the capacitance sensing array  604  shown in  FIGS. 6A-0  to  6 D- 1  represent a composite of different scans of the same array. 
       FIGS. 6A-0  and  6 A- 1  show a sense operation of an object  620 . A sense result  634  can determine various features of the objects as noted herein, or equivalents. 
       FIGS. 6B-0  and  6 B- 1  show a sense operation of a misaligned object  620 ′. It is assumed that an object  620 ′ should have an orientation as in  FIGS. 6A-0  and  6 A- 1 . As shown, for a rectangular object, misalignment can result in irregularities at any edges of sensed result  634 ′. 
       FIGS. 6C-0  and  6 C- 1  show a sense operation of a damaged or defective object  620 ″. It is assumed that an object  620 ″ should have a shape as in  FIG. 6A-0  and  6 A- 1 . As shown, for a defective object, a sensed result  634 ′ can have a smaller area or unexpected discontinuities. 
       FIGS. 6D-0  and  6 D- 1  show a sense operation for foreign object  622  present with a scanned object  620 . Such a scan operation can have a higher (or lower) capacitance threshold than those used for the object  620  itself. In the particular embodiment shown, the foreign object  622  can be a staple in or on a sheet of paper. Such a stable can result in a localized sense result  634  that surpasses a higher capacitance threshold.  FIG. 6D-1  shows the outline of the sheet of paper for reference. 
     As noted above, a capacitance sense array can be larger than a sensed object, or smaller than a sensed object.  FIGS. 7 to 12  show capacitance sense sections according to various embodiments. 
       FIG. 7  shows a capacitance sense section  704  that can scan opposing edges of an object  720 . In the embodiment shown, capacitance sense section  704  can span an entire length of an object  720 . In some embodiments, a capacitance sense section  704  can scan for alignment, number of objects, size, humidity, and foreign objects in a portion of the object  720 . 
       FIG. 8  shows a capacitance sense section  804  that can scan one edge of an object  820 . As in the case of  FIG. 7 , capacitance sense section  804  can span an entire length of an object  820 . In some embodiments, a capacitance sense section  804  can scan for alignment, number of objects, length (vertical direction in the figure), humidity, and foreign objects in a portion of the object  820 . 
       FIG. 9  shows a capacitance sense section  904  that can scan a horizontal strip of an object  920 .  FIG. 9  shows the intermediate portion of a scan operation. It is understood that the entire object  920  can traverse past the capacitance sense section  904 , or vice versa. In some embodiments, a capacitance sense section  804  can scan for alignment, number of objects, size, humidity, foreign objects, or defects in an object  920 . 
       FIG. 10  shows a capacitance sense section  1004  that can scan a horizontal strip at opposing edges of an object  1020 . It is understood that the entire object  1020  can traverse past the capacitance sense section  1004 , or vice versa. In some embodiments, a capacitance sense section  1004  can scan for alignment, number of objects, size, humidity, or foreign objects in a portion of the object  1020 . 
       FIG. 11  shows a capacitance sense section  1104  that can scan a horizontal strip at one edge of an object  1120 . It is understood that the entire object  1120  can traverse past the capacitance sense section  1104 , or vice versa. In some embodiments, a capacitance sense section  1104  can scan for alignment, number of objects, size (in one direction), humidity, or foreign objects in a portion of the object  1020 . 
       FIGS. 12A to 12C  show an edge scan according to an embodiment.  FIGS. 12A to 12C  show a capacitance sense array  1204 , and a misaligned object  1220  traversing the array over time. Sensors that detect the object are shown with an “X”. As shown, edge detection sensors will vary over time as a misaligned object passes over the sensor. 
     Having described various devices, systems and methods with block and other diagrams, additional methods according to embodiments will now be described in a series of flow diagrams. 
       FIG. 13  is a flow diagram of a method  1300  according an embodiment. A method  1300  can determine if an object is sensed ( 1302 ). Such an action can include sensing a change in capacitance at one or more sensors. If an object is sensed (YES form  1302 ) a method  1300  can derive various features of the object from the sensed capacitance values. In the embodiment shown, a method  1300  can include deriving object size values  1304  according to any of the embodiments herein, or equivalents. 
     A method  1300  can also include deriving a number of objects  1306 . Such an action can include comparing sensed capacitance values to one or more threshold values corresponding to numbers of objects. 
     A method  1300  can also include determining an alignment of object(s)  1308 . Such an action can include alignment checks as described herein, or equivalents. 
     A method  1300  can also include determining the presence of other features. Such an action can include scanning for the presence of defects or foreign objects as described herein, or equivalents. 
       FIGS. 14A to 14C  show a scan operation according to an embodiment.  FIG. 15  shows a method corresponding to the scan shown in  FIGS. 14A to 14C .  FIGS. 14A to 14C  show a capacitance sense section  1404  that can span a strip of an object  1420 . An object  1420  can traverse past the capacitance sense section  1404 . 
     Referring to  FIG. 15 , a method  1500  can include sensing an object with capacitance sense value ( 1502 ). It is assumed an object has a flat, rectangular shape. Leading features (e.g., corners) of an object can be sensed ( 1504 ). In the embodiment shown, this can include determining X1,Y1 and X2,Y2, as shown in  FIG. 14A . It is understood that such points can represent individual sensor values or groups of sensor values (average, local maximum, local minimum, etc.). From leading features, a method  1500  can derive a size and alignment value ( 1506 ). In the embodiment shown, a size value can be the size in a lateral direction (Xsize). 
     If an object size (e.g., Xsize) is not within limits (NO from  1506 ), predetermined actions can be taken ( 1512 ). In the embodiment shown, predetermined actions can include, but are not limited to, issuing an alarm, stopping processing, or adjusting processing. If a size is within limits (YES from  1508 ), a method  1500  can continue with a series of object checks, including determining if an alignment is within limits ( 1510 ). If the alignment is out of range (NO from  1510 ), predetermined actions can be taken. 
     A method  1500  can continue scanning the object. Such an action can include allowing a time to pass so that an object can be pushed further past a sensing array, or scanning a next row or sensors ( 1512 ). 
     A method  1500  can then determine a number of objects ( 1514 ). In some embodiments, such an action can include comparing one or more sensed capacitance values to one or more thresholds. If the number of objects exceeds some limit (YES from  1516 ), predetermined actions can be taken ( 1512 ). 
     A method  1500  can check for the presence of foreign objects ( 1518 ). In some embodiments, such an action can include comparing sensed capacitance values to one or more thresholds. In some embodiments, such a check can occur as the same time as  1514 . If a foreign object is detected (YES from  1520 ), predetermined actions can be taken ( 1512 ). 
     A method  1500  can then check for an object end ( 1522 ). Such an action can include sensing the absence of an object, via capacitance values. If an object end has not been sensed (NO from  1522 ), a method can check of a time out condition  1524  (i.e., the object has exceeded some size limit, or some other error has occurred). If a time out condition has not occurred (NO from  1524 ), a method  1500  can return to  1512 , scanning more of an object. If a time out condition has occurred (YES from  1524 ), predetermined actions can be taken ( 1512 ). 
     If an object end has been sensed (YES from  1522 ), trailing features (e.g., corners) of an object can be sensed ( 1526 ). In the embodiment shown, this can include determining X3,Y3 and X4,Y4, as shown in  FIG. 14C . Again, such points can represent individual sensor values or groups. With trailing features in combination with leading features, a method  1500  can derive another size value ( 1528 ). In the embodiment shown, a size value can be the size in another direction (Ysize). 
     If this other object size (e.g., Ysize) is not within limits (NO from  1530 ), predetermined actions can be taken ( 1512 ). If a size is within limits (YES from  1530 ), a method  1500  can continue processing the object ( 1532 ) (i.e., and operations section can perform operations on the object). Such an action can include any of the various operations describe herein, or equivalents. 
       FIG. 16  is a diagram showing an alignment check operation that can be included in particular embodiments.  FIG. 16  shows an object  1620  sensed by a capacitance sensor array. In  FIG. 16 , it is assumed an object  1620  is desired to be aligned with the sensor array. Thus, a misaligned object can have a leading row of sensors (Xstart to Xend) that is less than a nominal value (Xstart to Xnom). Of course, other embodiments can include any other suitable alignment checking technique. 
       FIGS. 17A and 17B  show method according to additional embodiments.  FIG. 17A  is a flow diagram of a method  1700  according to another embodiment. A method  1700  can include acquiring capacitance sensor values for an object (or objects) ( 1702 ). A number of objects can be derived from the sensed capacitance values ( 1704 ). If sensed values are not within a first range (NO from  1706 ), an alarm or other action can be taken ( 1708 ), indicating that more than one object has been sensed. 
     If sensed values are within a first range (YES from  1706 ), capacitance values can be checked to see if they are outside of another range ( 1710 ). If the sensed values are outside of this second range (YES from  1710 ), an alarm or other action can be taken ( 1712 ), indicating that a foreign object has been detected. 
     If sensed values are within expected ranges, a method  1700  can derive a humidity value for an object based on sensed capacitance values ( 1714 ). Processing of the object can then continue ( 1716 ). 
       FIG. 17B  is a graph showing one particular example of capacitance sense ranges according to a very particular embodiment. As shown, various thresholds can exist corresponding to number of objects. Further, a humidity range for a single object can also exist. Thus, based on a capacitance value, various numbers of objects can be derived (in the figure, 1, 2, 3 or 4+ objects). In addition,  FIG. 17B  shows a higher threshold for the detection of foreign objects. 
       FIGS. 18A and 18B , in combination, are a flow diagram of a method  1800  according another embodiment. Method  1800  can use the capacitance sensing of sheets of paper in a printing operation. 
     Referring to  FIG. 18A , a method  1800  can include starting to feed paper ( 1802 ). Paper being fed can be sensed with a capacitance sensing array ( 1804 ), as described in the various embodiments herein, or equivalents. Based on capacitance values, a method can derive features of the received paper, including sheet size, number of sheets, sheet alignment, and a staple check (i.e., the unwanted presence of a staple or other foreign object). 
     If an alignment value is not within limits (NO from  1808 ), a method can determine if an alignment adjustment operation was previously performed ( 1810 ). If an alignment adjustment has not previously been tried (NO from  1810 ), an alignment adjustment ( 1812 ) can be performed, and a method can return to ( 1808 ). If an alignment adjustment was previously tried (YES from  1810 ), the paper feed operation can be stopped and an alarm issued ( 1814 ). 
     If an alignment value is within limits (YES from  1808 ), a method can determine if the number of sheets is one ( 1818 ). If a capacitance value indicates more than one sheet has been detected (NO from  1816 ), and the paper feed operation can be stopped and an alarm issued ( 1814 ). 
     If the number of sheets has been determined to be one (YES from  1816 ), a method can determine if a foreign object (e.g., staple) has been detected ( 1818 ). If a foreign object is detected (YES from  1818 ), the paper feed operation can be stopped and an alarm issued ( 1814 ). 
     If no foreign object is detected (NO from  1818 ), a method can determine if a sheet size ( 1820 ). If a sheet size is not within limits (NO from  1820 ), the print output operation can be stopped and an alarm issued ( 1840 ). 
     If a sheet size is within limits (YES from  1820 ), a humidity of the paper can be derived from the capacitance values ( 1822 ). Print setting can be adjusted based on the derived humidity value ( 1824 ), and the sheet can be printed ( 1826 ). 
     Referring to  FIG. 18B , a method  1800  can further include starting to output a printed sheet ( 1828 ). A printed sheet can be sensed with a capacitance sensing array ( 1830 ). Alignment values for the printed sheet can be derived ( 1832 ). 
     If a printed sheet alignment value is not within limits (NO from  1834 ), a method  1500  follow steps like those described for inputting a sheet for processing (i.e.,  1808 ,  1810 ,  1812 ,  1814 ). A method can then determine if the print operation is a multi-sheet job ( 1840 ). If the job is not a multi-sheet job (NO from  1856 ), the job can be signaled as being complete ( 1856 ). 
     If the job is a multi-sheet job (YES  1856 ), a method can determine if sheets are to be collated ( 1842 ). If collation is to be done, collation can be performed ( 1844 ), and the number of sheets of the job can be derived from the capacitance values ( 1846 ). If the number of sheets is not the expected value (NO from  1848 ), the print output operation can be stopped and an alarm issued ( 1840 ). 
     If the number of sheets is the expected value (YES from  1848 ), a method can then determine if the print operation includes stapling ( 1850 ). If stapling is involved (NO from  1850 ), and the job can be signaled as being complete ( 1856 ). If the job includes stapling, a method can check for the stable using capacitance sense values ( 1852 ). If the staple is not detected (NO from  1854 ), an alarm can be issued ( 1858 ) and the job can be signaled as being complete ( 1856 ). If the staple is detected (YES from  1854 ), the job can be signaled as being complete ( 1856 ). 
       FIG. 19  shows printing device  1900  according to a particular embodiment. A printing device  1900  can include any of: a printer, copier or facsimile machine, as but a few examples. A device  1900  can include an object input  1902 , input feed path  1950 , first capacitance sense section  1904 , an operations section  1906 , output feed path  1952 , an object output  1908 , and optionally, a second capacitance sense section  1904 ′. An object input  1902  can be a paper feeder that can store a number of sheets. An input feed path  1950  can feed paper to an operations section  1906 , and can include guides, rollers, vacuum devices, or any other suitable devices to convey a sheet to the operations section  1906 . 
     A first capacitance sense section  1904  can sense sheets as they are fed to an operations section  1906 . A capacitance sense section  1904  can sense various features of a sheet according to any of the embodiments herein. Further, operations of the device can be controlled according to such sensing, including issuing alarms and stopping printing operations. In the embodiment shown, a first capacitance sense section  1904  can be smaller than a sheet, and can scan a sheet as it is conveyed to an operations section. While  FIG. 19  shows a first capacitance sense section  1904  proximate the operations section  1906 , such a section can be situated at any suitable location along the feed path between the object input  1902  and the operations section  1906 . 
     An operations section  1906  can print on a received sheet. In some embodiments, printing can be varied according to values received from a capacitance sense section  1904 . For examples, printing operations can be varied according to a sensed humidity, or varied according to a sensed alignment (i.e., printing can compensate for any misalignment for precision printing). 
     An output feed path  1952  can feed printed sheets to an object output  1908 , and can include guides, rollers, vacuum devices, or any other suitable devices to convey a printed sheet. An object output  1908  can receive printed sheets. 
     Optional second capacitance sense section  1904 ′ can sense printed sheets as are received. A capacitance sense section  1904  can sense various features of printed sheets according to any of the embodiments herein. Further, operations of the device can be controlled according to such sensing, including issuing alarms, etc. In the embodiment shown, a second capacitance sense section  1904 ′ can be larger than a sheet, and can scan a full sheet within object output  1908 . 
       FIG. 20  shows printing device  2000  according to another particular embodiment. A printing device  2000  can include sections like those of  FIG. 19 , and such like sections are referred to by the same reference character but with the leading digits being “20” instead of “19”. 
     Device  2000  can differ from the of  FIG. 19  in that first capacitance sense section  2004  can be larger than a printed sheet, while an optional second capacitance section  2004 ′ can be smaller than a printed sheet. Further, an input feed path 
     It is understood that capacitance sensing as described herein can operate on objects of various sizes and consistencies. In some embodiments, objects can be liquids. In such embodiments, liquid levels flowing through a course, such as a pipe can be detected. Similarly, features of flowing gases can be detected. Other objects can include hands identification cards, or any other suitable object that gives a variation in capacitance. 
     It should be appreciated that reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Therefore, it is emphasized and should be appreciated that two or more references to “an embodiment” or “one embodiment” or “an alternative embodiment” in various portions of this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined as suitable in one or more embodiments of the invention. 
     Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claims require more features than are expressly recited in each claim. Rather, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.