EP1444153A1 - Procede et systeme de detection d'une double entree - Google Patents

Procede et systeme de detection d'une double entree

Info

Publication number
EP1444153A1
EP1444153A1 EP02771926A EP02771926A EP1444153A1 EP 1444153 A1 EP1444153 A1 EP 1444153A1 EP 02771926 A EP02771926 A EP 02771926A EP 02771926 A EP02771926 A EP 02771926A EP 1444153 A1 EP1444153 A1 EP 1444153A1
Authority
EP
European Patent Office
Prior art keywords
edges
flat object
signal
overlapped
count
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02771926A
Other languages
German (de)
English (en)
Inventor
Charles Paul Scicluna
Jeffrey Charles Neal
Douglas Craig Browne
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Omron Canada Inc
Original Assignee
Omron Canada Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CA002361969A external-priority patent/CA2361969A1/fr
Application filed by Omron Canada Inc filed Critical Omron Canada Inc
Publication of EP1444153A1 publication Critical patent/EP1444153A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H7/00—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles
    • B65H7/02—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors
    • B65H7/06—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors responsive to presence of faulty articles or incorrect separation or feed
    • B65H7/12—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors responsive to presence of faulty articles or incorrect separation or feed responsive to double feed or separation
    • B65H7/125—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors responsive to presence of faulty articles or incorrect separation or feed responsive to double feed or separation sensing the double feed or separation without contacting the articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2301/00—Handling processes for sheets or webs
    • B65H2301/30—Orientation, displacement, position of the handled material
    • B65H2301/32—Orientation of handled material
    • B65H2301/321—Standing on edge
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2511/00—Dimensions; Position; Numbers; Identification; Occurrences
    • B65H2511/30—Numbers, e.g. of windings or rotations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2553/00—Sensing or detecting means
    • B65H2553/40—Sensing or detecting means using optical, e.g. photographic, elements
    • B65H2553/42—Cameras
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2701/00—Handled material; Storage means
    • B65H2701/10—Handled articles or webs
    • B65H2701/13—Parts concerned of the handled material
    • B65H2701/131—Edges
    • B65H2701/1315—Edges side edges, i.e. regarded in context of transport
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2701/00—Handled material; Storage means
    • B65H2701/10—Handled articles or webs
    • B65H2701/19—Specific article or web
    • B65H2701/1916—Envelopes and articles of mail

Definitions

  • the present invention relates to a method and apparatus using digital imaging and processing for detecting overlapped flat objects in a sequence of flat objects. More particularly, the invention is applicable to the detection of double or multiple fed mail pieces in a mail sorting apparatus.
  • Sheet feeders, bank note readers and mail piece sorting systems all employ feed mechanisms for picking off work pieces sequentially and singly from an input stack for transport along a feed path at relatively high speed.
  • the mail pieces are essentially flat rectangular objects having a pair of large flat surfaces and four edges, and the mail pieces are arranged with their planar surfaces along a common axis to form a stack.
  • a feeder mechanism picks off individual mail pieces from an input stack to an OCR (Optical Character Reader) which reads a forwarding address printed on the mail piece and directs the mail piece to one of several output stacks corresponding to the destination address.
  • OCR Optical Character Reader
  • the feed rate of such sorting apparatus is typically several thousand mail pieces per hour, so occasionally more than one mail piece is picked off by the feeder resulting in a multiple feed, also referred to in the art as a double feed.
  • a "double feed” is characterized by two or more mail pieces being stuck together generally along their flat sides with either one or more edges completely or partially overlapped. While current double feed detection systems will detect a partial or complete overlap, few are capable of also distinguishing a false double feed, which occurs when a relatively thick mail piece with a crinkled or creased edge is picked off or when the mail piece has a dark colour, is multicoloured or has a fold over. Of course, the detection of false double feeds should be avoided.
  • U.S. Patent No. 4,733,226 describes a system for detecting overlapped mail pieces where one mail piece hides another in the feed path.
  • a scanner is arranged along the feed path to detect the height of the mail piece as it moves past the scanner. Any changes in the height of mail pieces signals an overlap condition.
  • the system is limited to detecting variations in height, it cannot be used to detect an overlap where the mail pieces are the same height or where the mail pieces are fully overlapped.
  • United States Patent No. 4,160,546 there is described a system which uses changes in document translucency to trigger an overlap indication. While this system maybe effective for detecting documents that are translucent and have similar characteristics, it is not as effective for mail pieces which are typically opaque.
  • U.S. Patent No. 5,534,690 describes a system for counting the number of bank notes in a stack by imaging the entire side of a stack while the stack is kept stationary. The system determines the number ofitems in the stack by taking two images of the side of the stack at different illuminations. The number of lines in the two images is compared. The average number of lines between the two images indicates the number ofitems in the stack.
  • a limitation of this system is that the stacked items must be stationary so that a meaningful comparison can be made between the two images. Accordingly, this technique cannot be used for determining double feeds in a moving stream of objects such as in a mail sorting apparatus.
  • Other patents that describe counting techniques are, for example, disclosed in U.S. Patent No. 5,221,837.
  • DMD double feed detection
  • the invention provides a double feed detection system and method for detecting two or more mail pieces (e.g. envelopes), either partially or fully overlapped, passing simultaneously through a mail sorting and handling apparatus.
  • mail pieces e.g. envelopes
  • the DFD system includes a vision system with a digital camera for capturing and analyzing images of the bottom edges of mail pieces as they pass through the mail sorting apparatus, multiple photosensors for detecting and tracking the mail pieces through the mail sorting apparatus, and a controller for system control, system fault monitoring, and outputting double feed rejection signals to the mail sorting apparatus to enable the re-routing of detected double feeds.
  • a system is provided for detecting overlapped flat objects in a sequence of flat objects, where the flat objects have at least one of their edges exposed for viewing as they pass along a feed path.
  • the system includes: a sensor for generating a signal in response to detecting a flat object in the feed path; a camera responsive to the signal for capturing a digital image of the exposed edges of the detected flat object in the feed path; and a vision system coupled to the camera for receiving the digital image.
  • the vision system analyses at least a portion of the image to determine a pixel density variation along a direction perpendicular to the edges and uses the pixel density variation to output an indication of the number of edges in the image.
  • the DFD method is implemented in part by software run by the vision system. According to this method, an image of the bottom edges of a mail piece is captured and an inspection is performed on at least a portion of this image to determine if the mail piece is of a predetermined thickness. If the mail piece is of the predetermined thickness, low sensitivity settings of the expected average edge width are used by the software to count the number of edges. If the mail piece is less than the predetermined thickness, high sensitivity settings of the expected average edge width are used to count the number of edges. If the mail piece is of the predetermined thickness and the measured number of edges is less than two, there is no double feed and an output from the vision system to the controller indicates an "OK" condition for the mail piece.
  • the output to the controller indicates a "Double Feed" condition for the mail piece. If the mail piece is less than the predetermined thickness and the measured number of edges is less than two, there is no double feed condition and the output to the controller indicates an "OK" condition for the mail piece. If the mail piece has less than the predetermined thickness and the measured number of edges is greater than two, there is a double feed and the output to the controller indicates a "Double Feed” condition for the mail piece.
  • the output to the controller indicates an "OK" condition for the mail piece.
  • the measured number of edges is equal to two and the measured edge pitch is greater than a predetermined threshold, there is a double feed and the output to the controller indicates a "Double Feed" condition for the mail piece.
  • a method for detecting overlapped flat objects in a sequence of flat objects where the flat objects have at least one of their edges exposed for viewing as they pass along a feed path.
  • the method includes the steps of: selecting a flat object in the feed path; capturing a digital image of the exposed edges of the selected flat object; processing at least a portion of the captured image encompassing the edges to determine a pixel density variation in a direction across the edges; analysing the pixel density variation to identify maxima and minima in the variation, where a start of an edge is identified by a maximum and an end of an edge is identified by a minimum; and, counting the maxima and minima to output an indication of the number of edges in the image.
  • the method may further include determining an edge width of the flat object.
  • the method of dete ⁇ nining an edge width of the flat object may include; computing an average pixel density for the processed portion; assuming a first edge width if the average density is below a predetermined level; and, assuming a second edge width if the average density is above the predetermined level.
  • the method of counting may further include: counting maximum and minimum pairs that are spaced by less than the first edge width if the average density is below the predetermined level to output the indication of the number of edges; and, counting maximum and minimum pairs that are spaced by more than the second edge width if the average density is above the predetermined level to output the indication of the number of edges.
  • the DFD method is also implemented in part by software that is run on the controller.
  • the controller receives outputs from the vision system indicating that each passing mail piece is either "OK” or is a "Double Feed”.
  • the controller analyses these outputs from the vision system, information from multiple photosensors that track the progress of mail pieces through the mail sorting, and monitored fault information to determine when or if a double feed rejection signal should be sent to the mail sorting apparatus to enable the re-routing of detected double feeds.
  • FIG. 1 is a block diagram illustrating a mail sorting system with an incorporated DFD system in accordance with an embodiment of the invention
  • FIG. 2 is a block diagram illustrating a double feed detection ("DFD") system in accordance with an embodiment of the invention
  • FIG. 3 is a simplified perspective view illustrating a DFD system in accordance with an embodiment of the invention.
  • FIGS. 4(a), 4(b), and 4(c) are partial plan views of the DFD system illustrating the relationship between passing mail pieces and photosensors PI and P2;
  • FIG. 5 is a partial plan view of the DFD system illustrating the relationship between passing mail pieces and photosensors PI, P2, and P3;
  • FIG. 6(a) is a screen capture illustrating an image of mail piece bottom edges captured by a camera
  • FIGS. 6(b) and 6(c) show a schematic diagram of the screen image of FIG. 6 (a) and its corresponding density variation
  • FIG. 7 is a flow chart illustrating a general method for detecting a double feed condition using a vision system in accordance with an embodiment of the invention
  • FIG. 8 is a pseudocode listing corresponding to the flow chart of FIG. 7;
  • FIG. 9 is a flow chart illustrating a general method for providing a double feed rejection signal to a sorter using a controller in accordance with an embodiment of the invention.
  • FIG. 1 is a block diagram of a mail sorting system 100 which includes a double feed detection (DFD) system 200 in accordance with an embodiment of the invention.
  • the mail sorter 100 includes an input stacker 110 for supporting a stack of mail pieces to be sorted, a feeder mechanism 120 for picking off mail pieces, preferably one at a time, and transporting them by a conveyor belt sequentially along a feed path 132 past an OCR (optical character recognition) system 140 to one or more destination bins or output stacks 150.
  • OCR optical character recognition
  • the OCR system 140 is used to determine the destination address of the mail piece and thereby control an appropriate gate to a destination bin.
  • the arrow 130 indicates the direction of flow of the mail piece along the feed path 132.
  • the feeder mechanism 120 typically picks off mail pieces at a rate of several thousand per hour and may not always pick off a single mail piece from the input stacker, but may instead pick off two or more overlapped mail pieces. Accordingly, the present invention addresses this problem by providing a DFD system 200 for detecting double feeds and initiating appropriate action to the sorter, such as providing a signal to divert overlapped mail pieces from the feed path 132 to a rejection bin.
  • the DFD system 200 is preferably located between the feeder 120 and the OCR 140 and generally provides three functions: edge detection, overlap detection, and mail piece tracking.
  • FIG.2 is a block diagram of a DFD system 200 in accordance with an embodiment of the invention.
  • the DFD system 200 includes a programmable logic controller (PLC) 270 which is interfaced to a vision system 260 and its associated camera and lamp 210 for edge detection; photo sensors PI, P2, P3 positioned along the feed path for overlap detection, triggering the vision system and mail piece tracking; an output device 280; and a system panel 291.
  • the output device 280 provides double feed rejection signals generated by the DFD system 200 to the sorter system 100.
  • the output device 280 may also include a CD-ROM, a floppy disk, a printer, a digital output (e.g. solid state device or relay contact), or a network connection.
  • the panel 291 may include an input device 290 and a display 292.
  • the input device 290 may include a keyboard, mouse, trackball, control switches, or similar devices.
  • the display 292 may include a CRT screen, LCD screen, indication lamps, or similar devices.
  • the vision system 260 includes image-processing software for computing the number of edges in a passing mail piece. The vision system is coupled to receive inputs from the photosensor P2 230 and the camera 250. The vision system 260 may also be interfaced to an input device 290 and display 292 either directly or through a panel 291. As will be described below, the vision system 260 provides a double feed indication to the controller 270.
  • the vision system 260 and controller 270 may be a single unit.
  • the vision system 260 and/or controller 270 may include an input device, a central processing unit or CPU, memory, a display, and an output device.
  • the CPU may include dedicated co-processors and memory devices.
  • the memory may include RAM, ROM, databases, or disk devices.
  • the DFD system 200 may be implemented with the following hardware components, available from Omron Canada Inc., or equivalents: Lamp 210: Model 101K12351; Photosensors 220, 230, 240 Model E32-T14 with amplifier E3X-F21; Camera 250 Model F150-S1A; Vision System 260 Model F150-C10E-3 with console F150-KP; Controller 270 Model CPM2C-20CDTC-D; Output Device 280 Model CPM2C-20CDTC-D (digital outputs); Input Device 290 Model NT2S-SF123B-E (function keys); Display Model 292 NT2S- SF123B-E (2 line LCD display).
  • Lamp 210 Model 101K12351
  • Photosensors 220, 230, 240 Model E32-T14 with amplifier E3X-F21 Camera 250 Model F150-S1A
  • Vision System 260 Model F150-C10E-3 with console F150-KP
  • FIG. 3 is a block diagram of the relative positions of the various components in the DFD system 200 according to an embodiment of the present invention.
  • the conveyor belts and mechanical devices for moving mail pieces 310 along the feed path 130, 132 are well known and have been omitted.
  • a typical single fed mail piece is indicated by the numeral 310, while a typical double feed is indicated by the numeral 320.
  • the double feed 320 is shown as two overlapped envelopes 321, 322.
  • Mail pieces 310 typically pass along the feed path 130, 132 in an upright orientation with at least one of their edges 330 visible to the camera 250, which is positioned below the feed path 130.
  • the visible edge is at least the bottom edge of one mail piece 310 and passes through an imaging region of the camera lens.
  • the photocell sensor P2230 is positioned in the feed path 130, 132 such that the camera 250 is triggered when a leading edge of the mail piece 310 passes the sensor 230 and the camera 250 captures images of the bottom edges 330 of passing mail pieces 310.
  • the lamp 210 is directed toward me bottom edges 330 to illuminate them for improved image capture by the camera 250.
  • the camera lens 250 need not be mounted perpendicular to the mail piece path 130, 132 but may be mounted at an angle to the feed path 130, 132.
  • the imaging region of the camera is spaced a distance L, along the feed path, from photosensor P2230 such that when a mail piece 310 is detected by photosensor P2 230, a signal is sent by the photosensor P2230 to the vision system 260, which in turn controls the camera 250 to capture an image of the bottom edge 330 of the passing mail piece 310.
  • This distance is chosen so that the camera captures an image of the bottom edge 330 of the shortest allowable mail piece 310 passing along the feed path 130. For example, if the shortest allowable bottom edge of the mail piece 310 is 140 mm, then the camera 250 would typically be spaced approximately 130 mm from photosensor P2230.
  • the digital image-processing software executed by the vision system 260 is used to analyze the image 600 to determine the number of edges present using any method known in the art.
  • FIG. 6(a) is a screen capture illustrating an image 600 of mail piece bottom edges 330 captured by a camera 250.
  • the image 600 is typically stored digitally in the memory of me vision system 260.
  • the image 600 may also be displayed to a user on the display 292.
  • the bottom edge 330 of the mail piece 310 typically appears as a line 610 against a background 620 in the captured image 600.
  • the image 600 contains two lines 610, 611, indicating that the mail piece 310 has two bottom edges 330.
  • the mail piece 310 may consist of two envelopes.
  • the user defines a measurement region 630 in which to perform a density variation analysis within the captured image 600.
  • This region will encompass the mail piece bottom edges 330 passing along the feed path 130, 132.
  • the software determines the presence of edges through an analysis of pixel density variations across the selected measurement region 630 of the digital image.
  • FIGS. 6(b) and 6(c) which are, respectively, a schematic representation of an acquired image in the measurement region 630 and a corresponding graph of the density variation as a percentage of dark to light pixels over the measurement region 630.
  • edges are detected by analysing points on the density variation graph over the measurement region 630 and in a direction perpendicular to the edges.
  • This perpendicular direction may be inferred by the software as the orientation of the camera 250, and hence the captured image 600, is known relative to the feed path direction 130.
  • the points X correspond to maxima 604 and minima 605 that exceed an edge level threshold value 606, 607 and are detected as beginnings or ends of edges 608.
  • the software counts the number of maxima and minima, and depending on the sensitivity settings (as explained below), infers the number of edges 608.
  • an average density threshold parameter for the measurement region 630 is specified by a user.
  • the software will perform an average density inspection on the measurement region 630 to determine a measured average density.
  • the measured average density is the ratio of pixels corresponding to lines 610, 611 to pixels corresponding to background 620 within the measurement region 630.
  • the software will compare the average density threshold parameter to the measured average density to determine if a mail piece is thick (i.e. large) or thin (i.e. small). If the measured average density is above the average density threshold parameter, then the mail piece will be considered to be thick. If the measured average density is below the average density threshold parameter, then the mail piece will be considered to be thin.
  • the software will count the number of edges using a low sensitivity inspection for thick mail pieces and using a high sensitivity inspection for thin mail pieces.
  • the user specifies a set of parameters for each of the low and high sensitivity inspections. These parameters are set by the user as follows: first, the user defines an expected average edge width parameter 640 for both thick and thin mail pieces; second, the user defines an expected average edge pitch parameter 650 also for both thick and thin mail pieces.
  • the expected average edge pitch is the expected distance between the center of the edges of two double fed mail pieces 610, 611, 321, 322.
  • the user then defines a number of edges parameter 660 that will represent a single feed condition. This number will generally be "1". Finally, the user indicates to the software through a judgement parameter 670 that the entered parameters represent a single feed or "OK" condition. As will be described below, the software uses these parameters to determine if a double feed condition exists.
  • the low and high sensitivity values for the expected average edge width and edge pitch parameters allow for differentiated handling of thick, thin, and dark colored (e.g. red-striped edge envelopes) mail pieces. In general, thin mail pieces usually have crisp, well-defined edges. On the other hand, thick mail pieces often have creases and dents in their edges and, as such, they may be mistakenly considered as double feeds.
  • the average density inspection is performed on the measurement region 630 to determine if the mail piece is thick or thin, and hence, select between the results of the low and high sensitivity inspections.
  • the high sensitivity inspection is performed to identify, for example, dark colored mail piece edges that do not generally show up well in the captured image 600 (i.e., dark colored mail pieces may be similar in colour to the background).
  • the high sensitivity inspection results in a first edge count.
  • the low sensitivity inspection is performed to avoid false edge counts due to creases and dents in thick mail pieces.
  • the low sensitivity inspection results in a second edge count.
  • the average density inspection is performed. If the average density inspection determines that the mail piece is thick, the second edge count (i.e. at low sensitivity) is chosen. If the average density inspection determines that the mail piece is thin, the first edge count (i.e. at high sensitivity) is chosen.
  • the chosen edge count is used to determine if a double feed condition exists as will be described with reference to FIG. 7 below.
  • the first edge count i.e. at high sensitivity
  • the software produces the first edge count by counting maximum and minimum pairs 604, 605 that are spaced less than the high sensitivity expected average edge width setting 640. In this way, maxima and minima corresponding to each thin mail piece edge are generally included in the first edge count.
  • the second edge count i.e. at low sensitivity
  • the measured average density is above the average density threshold (i.e.
  • FIG. 7 is a flow chart illustrating a general method for detecting a double feed condition using the vision system 260 in accordance with an embodiment of the invention.
  • the flow chart is shown generally by numeral 700.
  • the method begins.
  • an inspection is performed to determine if the mail piece 310 is thick or thin.
  • low sensitivity settings are used by the software to count the number of edges.
  • high sensitivity settings are used to count the number of edges.
  • the mail piece is thick and the measured number of edges 681 is less than 2, there is no double feed and the output to the controller 270 indicates an "OK" condition for the mail piece.
  • the output to the controller 270 indicates a "Double Feed” condition for the mail piece.
  • the output to the controller 270 indicates an "OK" condition for the mail piece.
  • the output to the controller 270 indicates a "Double Feed” condition for the mail piece.
  • step 708 if the mail piece is thin and the measured number of edges 681 is equal to 2 and the measured edge pitch 682 is smaller than a predetermined threshold, there is no double feed and the output to the controller 270 indicates an "OK" condition for the mail piece.
  • the mail piece is thin and the measured number of edges 681 is equal to 2
  • the measured edge pitch 682 is greater than a predetermined threshold (i.e., expected average edge pitch)
  • a predetermined threshold i.e., expected average edge pitch
  • FIG. 8 is a pseudocode listing corresponding to the flow chart of FIG. 7. Note that while the vision system 260 need not be programmed using a logic flow sequence, for clarity, the method illustrated by the flowchart of FIG. 7 is presented as pseudocode in FIG. 8.
  • the software has analyzed the measurement region 630 and has presented measured values 680, 681, 682, 683 for the judgement 670, number of edges 660, edge pitch average 650, and edge width average 640 parameters, respectively. While the measured number of edges 681 is "2", the software, based on a combination of criteria as described, provides a measured judgement 680 of "OK". In other words, a double feed condition does not exist even though two edges have been detected. The mail piece may be, for example, a "fold over" rather than two envelopes that have stuck together. If a double feed condition exists, then a signal is output from the vision system 260 to the controller 270. This signal indicates if the mail piece is "OK" or if it is a "Double Feed".
  • the DFD system 200 includes three photosensors PI 220, P2230, and P3 240.
  • the first two photosensors PI 220, P2 230 are used to detect a double feed condition in accordance with a further embodiment of the invention.
  • FIGS. 4(a), 4(b), and 4(c) are partial plan views of the DFD system 200 illustrating the relationship between passing mail pieces 310 and photosensors PI 220 and P2230.
  • the first two photosensors PI 220, P2 230 are spaced in the mail piece path 130 at a distance greater than the length of the largest allowable mail piece (e.g.
  • the two photosensors PI 220, P2 230 may be spaced approximately 270 mm apart.
  • the first photosensor PI 220 As a mail piece 310 passes through the feeder 120 and into the OCR system 140, it turns on the first photosensor PI 220. If the first photosensor PI 220 remains on until the second photosensor P2 230 is turned on, a double feed 320 condition exists. If both photosensors PI 220, P2230 are turned on simultaneously, this indicates that the mail piece is longer than the maximum allowable length, which may mean that two mail pieces 321, 322 are passing through the sorter at the same time.
  • the status of photosensors PI 220 and P2230 is monitored by the controller 270.
  • the second photosensor P2230 is also monitored by the vision system 260.
  • a signal is provided to the vision system 260 indicating that an image is to captured by the camera 250.
  • the vision system 260 processes the image captured by the camera 250 to determine the number of edges of a passing mail piece 310 and, hence, whether there is a double feed.
  • the DFD system 200 includes two means for detecting double feeds; a first and second photosensors means and a vision system means. Note that the DFD system 200 may operate with one or both of these double feed detection means. FIG.
  • FIG. 5 is a partial plan view of the DFD system 200 illustrating the relationship between passing mail pieces 320 and photosensors PI 220, P2230, and P3 240.
  • the third photosensor P3 240 is required because double feed detection is typically performed by the DFD system 200 at a distance along the mail piece path 130 spaced before the spot 340 in the path 130 where a double feed rejection signal is typically issued by the DFD system 200, via its output device 280, to the sorter system 100.
  • the third photosensor P3 240 allows the DFD system 200 to track the mail piece 320 through the sorter processing apparatus 140 and to provide the double feed rejection signal at the appropriate time.
  • the DFD system 200 performs several self-diagnostic routines. In particular, the DFD system 200 monitors the number of double feeds detected to determine if a fault or malfunction has occurred. With respect to double feed counts, a fault may have occurred if the count is too low (i.e. a "too few double feeds fault") or too high (i.e. a "too many double feeds fault"). Normally, a number of double feeds will occur during a routine sorting operation. If no double feeds are detected, a malfunction may have occurred. For example, the camera lamp 210 may have burnt out.
  • the DFD system 200 will generate a too few double feeds fault signal if a double feed has not been detected in the last 5,000 (or 10,000) mail pieces that have passed through the sorter 100.
  • the too few double feeds fault may be automatically reset when the DFD system 200 subsequently detects a double feed.
  • a second type of fault that the DFD system 200 checks for is too many double feeds. This condition may indicate a more severe malfunction in the DFD system 200. For example, the lens of the camera 250 may be dirty or the DFD system 200 may have been set up incorrectly. If a too may double feeds fault occurs, then the DFD system 200 may generate a fault alarm and may shut down its output 280 to the sorter 100. The too many double feeds fault may be automatically reset upon a detected reduction in the number of double feeds.
  • the DFD system 200 will determine two types of too many double feeds faults, namely, a "50 in a row OR 5%" fault and a "50 in a row OR 50%" fault.
  • C be a mail piece count
  • X be a count increment
  • Y be an alarm level.
  • X a double feed is not detected (i.e. a single feed occurs)
  • the controller 270 momtors the photosensors PI 220, P2 230, P3 240, and the vision system 270 to determine if a double feed has occurred. If a double feed is detected by the controller 270, it is repo ⁇ ed to the so ⁇ er 100 through the output device 280 of the DFD system 200 and to the user locally through the devices mounted on the system panel 291.
  • the controller 270 also performs self-diagnostic functions for the DFD system 200 as described above and maintains statistics including mail piece and double feed counts.
  • the controller 270 performs functions including the following: 1. Checks if a mail piece 310 passing through the DFD system 200 is too long, hi general, a mail piece will be too long if, for example, the mail piece consists of two overlapping and offset envelopes. To perform this check, the controller 270 monitors photosensors PI 220 and P2230 as described above. The controller 270 (a) continuously checks when photosensor PI 220 was last unblocked, and (b) determines that there is a double feed if photosensor P2 230 is blocked and photosensor PI 220 has not become unblocked.
  • the mail piece 310 is longer than the distance between photosensors PI 220 and P2230 and therefore the mail piece 310 is a double feed.
  • the mail piece 310 simply may be longer than the longest allowable length in which case it should also be rejected.
  • the vision system 260 will provide a double feed indication if the mail piece 310 consists of, for example, two fully overlapped envelopes (i.e. overlapped but not necessarily offset).
  • the vision system 260 typically provides the controller 270 with a gate signal which indicates that the double feed output is ready for scanning by the controller 270.
  • the controller ⁇ 270 Upon receipt of the gate signal, the controller ⁇ 270 will scan the double feed output from the vision system 260 to determine if a double feed condition exists.
  • the double feed output from the vision system 260 is typically a solid state device output or relay contact (e.g. a logical high or a normally open contact).
  • the controller 270 determines if a double feed rejection signal should be output to the so ⁇ er 100, 140 by monitoring photosensor P3 240, fault status (as described above), and corresponding bits of the mail piece present and double feed shift registers.
  • the controller 260 checks for the setting of corresponding bits for the mail piece in the mail piece present and double feed shift registers. If there is no fault (i.e. alarm), photosensor P3 240 is on, and the corresponding shift register bits are both set, then the controller provides a double feed rejection signal to the sorter 100, 140 via the output device 280.
  • the controller 270 will generate a fault alarm if too many mail pieces are double feeds (e.g. the vision system 260 is malfunctioning). In this event, the controller 270 will turn the double feed rejection signal off. In addition, the controller 270 will generate a fault alarm if too few mail pieces are double feeds. With respect to statistics, the controller 270 maintains and increments counters for both mail pieces passing through the DFD system 200 and for double feeds detected.
  • the setup mode for configuring the DFD system 200.
  • the setup of the DFD system 200 is described in greater detail below.
  • the controller 270 measures how long it takes for a mail piece to travel from photosensor P2230 to photosensor P3 240. This information is used to select which bits in the mail piece present and double feed shift registers are to be monitored (i.e. in function 4 above).
  • a flow chart 900 illustrating a general method for providing a double feed rejection signal to a sorter 100 using a controller 270 in accordance with an embodiment of the invention.
  • the method begins.
  • the controller 270 checks if a double feed condition exists by monitoring both the photosensors PI 220, P2230, and the vision system 260.
  • the mail piece 310 is marked by setting a bit in the double feed shift register.
  • a corresponding bit is set in the mail piece present shift register.
  • a delay is introduced to allow the mail piece to travel through the DFD 200 and sorter 100 systems.
  • the controller 270 monitors photosensor P3 240 until the mail piece 310 passes.
  • the controller 270 checks for a fault alarm and for the setting of corresponding bits in the mail piece present and double feed shift registers.
  • the double feed rejection signal is turned on.
  • the mail piece and double feed counters are incremented.
  • the method ends.
  • Data Carrier Product The sequences of instructions which when executed cause the method described herein to be performed by the DFD system 200 of FIG. 2 can be contained in a data carrier product according to an embodiment of the invention.
  • This data carrier product can be loaded into and run by the DFD system 200 of FIG. 2.
  • Computer Software Product The sequences of instructions which when executed cause the method described herein to be performed by the DFD system 200 of FIG. 2 can be contained in a computer software product according to an embodiment of the invention. This computer software product can be loaded into and run by the DFD system 200 of FIG. 16.
  • Integrated Circuit Product The sequences of instructions which when executed cause the method described herein to be performed by the DFD system 200 of FIG. 2 can be contained in an integrated circuit product including a coprocessor or memory according to an embodiment of the invention. This integrated circuit product can be installed in the DFD system 200 of FIG. 2.
  • the invention described herein provides a double feed detection (“DFD”) system for detecting two or more mail pieces (e.g. envelopes), either partially or fully overlapped, passing simultaneously through a mail sorting and handling apparatus.
  • DFD double feed detection
  • MLOCR Multi-Line Optical Character Readers
  • SLOCR Single Line Optical Character Readers
  • BCS Bar Code Sorters
  • DBCS Delivery Bar Code Sorters
  • EBCS Enhanced Bar Code Sorters
  • ISS Input Sub System family devices
  • AFCS Advanced Facer Canceller Systems
  • AFCS ISS Alcatel Flat Sorter Machines
  • FSM Flat Sorter Machines
  • LSM Letter Sorter Machines

Landscapes

  • Controlling Sheets Or Webs (AREA)
  • Sorting Of Articles (AREA)

Abstract

La présente invention concerne un système de détection d'objets plats superposés (320) qui se trouvent dans une suite d'objets plats (310, 340) disposés de telle sorte qu'au moins un de leurs bords (330) est exposé pour être inspecté lorsqu'ils circulent sur un chemin d'alimentation (30, 132). Le système comprend un capteur (P1, P2, P3) qui génère un signal en réponse à la détection d'un objet plat (310) sur le chemin d'alimentation (130, 132) et une caméra (250) qui réagit au signal pour saisir une image numérique des bords exposés (330) de l'objet plat détecté (310) dans le chemin d'alimentation. Un système de vision est couplé à la caméra (250) pour recevoir l'image numérique. Le système de vision analyse au moins une partie de l'image pour déterminer une variation de la densité des pixels dans un sens perpendiculaire aux bords (330) et utilise la variation de la densité des pixels pour produire une indication du nombre de bords (330) présents dans l'image.
EP02771926A 2001-11-14 2002-10-30 Procede et systeme de detection d'une double entree Withdrawn EP1444153A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
CA2361969 2001-11-14
CA002361969A CA2361969A1 (fr) 2001-11-14 2001-11-14 Methode et systeme de detection d'alimentation double dans une machine a trier les lettres
CA2401401 2002-09-05
CA002401401A CA2401401A1 (fr) 2001-11-14 2002-09-05 Methode et systeme de detection d'alimentation double
PCT/CA2002/001622 WO2003042082A1 (fr) 2001-11-14 2002-10-30 Procede et systeme de detection d'une double entree

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EP1444153A1 true EP1444153A1 (fr) 2004-08-11

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Application Number Title Priority Date Filing Date
EP02771926A Withdrawn EP1444153A1 (fr) 2001-11-14 2002-10-30 Procede et systeme de detection d'une double entree

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EP (1) EP1444153A1 (fr)
JP (1) JP2005508818A (fr)
CA (1) CA2401401A1 (fr)
WO (1) WO2003042082A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003047773A2 (fr) * 2001-12-03 2003-06-12 Siemens Aktiengesellschaft Dispositif et procede de detection d'envois postaux chevauchants
GB0418040D0 (en) * 2004-08-12 2004-09-15 Wessex Technology Opto Electro Improvements in double feed mail detection
FR2948109B1 (fr) * 2009-07-16 2011-06-17 Solystic Dispositif de depilage d'objets plats avec detection de la trace des objets depiles
DE102010014105A1 (de) 2010-04-07 2011-10-13 Siemens Aktiengesellschaft Verfahren und Vorrichtung zum Vermessen von Gegenständen während des Transports

Family Cites Families (5)

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Publication number Priority date Publication date Assignee Title
FR2057309A5 (fr) * 1969-08-11 1971-05-21 Robotron Veb K
FR2546083B1 (fr) * 1983-05-20 1986-04-18 Hotchkiss Brandt Sogeme Dispositif de detection de prises multiples d'objets
US4733226A (en) * 1986-01-07 1988-03-22 Nec Corporation Overlapped-transfer detecting apparatus for mail article
US5331151A (en) * 1993-01-25 1994-07-19 Pressco Technology, Inc. Multiple envelope detector
DE19842192A1 (de) * 1998-09-15 2000-03-16 Roland Man Druckmasch Einrichtung zur Überwachung des Bogenlaufes einer bogenverarbeitenden Vorrichtung

Non-Patent Citations (1)

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Title
See references of WO03042082A1 *

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JP2005508818A (ja) 2005-04-07
CA2401401A1 (fr) 2003-05-14

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