Patent Description:
As an example, in commonly assigned <CIT> hardcopy media transport cylinder with a specialized profile is used to enhance the diagnostic qualities of the hardcopy media transport noise in order to detect hardcopy media wear. However, this specialized hardcopy media transport cylinder is designed to induce stresses into the hardcopy media that interfere with smooth hardcopy media transport at high transport speeds.

Other known methods of detecting jams include using optical or mechanical sensors in order to detect the times of the passage of a sheet of hardcopy media at various locations along the hardcopy media transport path. If the hardcopy media does not arrive at a given location at a given amount of time after the start of transport, a hardcopy media jam is inferred. The problem with this approach is that optical and mechanical sensors are highly localized in physical detection range, requiring the use of several such sensors situated along the hardcopy media transport path.

Commonly assigned <CIT> describes placing a microphone near the beginning of a hardcopy media feed path in order to detect the sound of a hardcopy media jam in progress. The signal from the microphone is processed by counting the number of sound samples above a given threshold within a sampling window of a given width. If the count is sufficiently large a hardcopy media jam is signaled. In this approach, no information is provided about the location of the hardcopy media as it moves along the transport path. Thus, although sound may be used to detect a jam in progress, information regarding the location of the jam that may be provided by optical or mechanical sensors as discussed above is unavailable.

There remains a need for a fast and robust technique to indicate hardcopy media jams along a hardcopy media transport path that uses a single hardcopy media sensor and processes the signals from the hardcopy media sensor simply, and in a way that incorporates the location of the hardcopy media along the hardcopy media transport path.

<CIT> discloses a paper conveying apparatus with a central processing unit which determines whether a jam has occurred at positions at which the microphones are arranged based on the sound signals which the first microphone, the second microphone and the third microphone generate.

<CIT> discloses a paper sheet conveying apparatus with a sound collecting microphone along a paper sheet conveyance path, in which the type of jam (sheet conveyance abnormality) caused on the paper sheet conveyance path is specified based on conveyance sound detected by the sound collecting microphone.

<CIT> discloses a medium transport system which comprises a microphone for detecting the sound of the medium being conveyed and producing a signal representing the sound; a processor for producing sound values from the signal and: computing a moving window sum, a high amplitude count and a post roller sum responsive to the sound values; and indicating the medium jam responsive to the moving window sum, high amplitude count, or post roller sum.

<CIT> (A2) relates to a paper conveying apparatus, abnormality detection method, and computer program.

The present invention represents a method of indicating a medium jam along a medium transport path in a scanner or other media transport device. The scanner includes one or more rollers for use in conveying the medium along the medium transport path. One or more microphones are included in the scanner and detect the sound of the medium being transported. The microphones produce signals representing the sound, which are sent to a processor which produces sound values from the signals. Various sound amplitude maximum values are computed, including a pre-transport path maximum amplitude values responsive to the sound values from a plurality of microphones from a region before the medium transport path, transport path maximum amplitude values responsive to the sound values from a plurality of microphones from a region within the medium transport path, and post-transport path maximum amplitude values responsive to the sound values from a plurality of microphones from a region after the medium transport path. The processor analyzes these various computed sound values and indicates a medium jam responsive to the maximum amplitude values when the computed sound values go above what is expected for normal operation.

The processor may be included in a computer system that is part of, or in communication with, the scanner and microphones. The processor may execute computer program instructions stored on a non-transitory computer-readable medium which cause the processor to acquire sound signals from the plurality of microphones responsive to the sound generated by a medium being transported along a medium transport in the scanner. The computer-readable medium includes further instructions enabling the processor to determine whether a jam has occurred based on the sound signal values according to a detection method, as described in detail below.

Based on the sound signals received, the computer may change the detection method on-the-fly. For example, depending on where the sound values come from within a sound profile established from signals from the various microphones, loudness thresholds for indicating a jam may be adjusted.

The one or more microphones can detect the sound of a medium jamming over a larger physical area than optical or mechanical methods, which are localized in nature. As a result, one microphone can replace the need for several optical or mechanical sensors. By using multiple microphones, a larger area can be monitored and signals from the multiple microphones can be compared against each other to determine the location of the sound source better than one microphone could. Determining the location of the noise source may be helpful in determining the location of the jam, as it is typical for the jam to cause the detected noise, and thus the noise source is often the jam location. Additionally, the area covered by any one microphone depends on sound path from the sound source to the microphone, and structural features could block sound from reaching the microphone. Further, there could be noisy components such as the rollers that make it hard to decipher the sound beyond the roller. Thus, to provide full jam detection coverage, multiple microphones may be installed along the transport path. The sound values over the entire medium transport path and at specific locations along the medium transport path are processed, thereby improving medium jam detection accuracy and reliability. The sound value processing is simple as it comprises computing sums of the sound values produced from the microphone signals. More computationally intensive methods such as transformations into frequency space or signal processing methods such as median filtering are avoided, resulting in sound value processing that requires substantially less computation resources and processing time. In addition, training and calibration techniques may be applied in order to optimize and simplify parameter settings.

The present invention is directed to a media transport system, and in particular to a system and method for detecting media jams within the media transport system. The method may be carried out using a process stored as instructions on a computer program product. The computer program product can include one or more non-transitory, tangible, computer readable storage medium, for example; magnetic storage media such as magnetic disk (such as a floppy disk) or magnetic tape; optical storage media such as optical disk, optical tape, or machine readable bar code; solid-state electronic storage devices such as random access memory (RAM), or read-only memory (ROM); or any other physical device or media employed to store a computer program having instructions for controlling one or more computers to practice the method according to the present invention.

<FIG> shows a medium transport system <NUM> in the form of a document scanner that includes a scanner base <NUM>, a scanner pod <NUM>, an input tray <NUM>, an output tray <NUM>, and an operator control panel <NUM>. The scanner pod <NUM> covers the top surface of the medium transport system <NUM> and connects to the scanner base <NUM> with hinges. The hinges allow the document scanner to be opened and closed when there is a media jam within the scanner or when the medium transport system <NUM> needs to be cleaned.

The input tray <NUM> is connected to the scanner base <NUM> with hinges, allowing the input tray <NUM> to be opened and closed as illustrated by an arrow A3. The input tray <NUM> may be opened at times of scanning and closed when the medium transport system <NUM> is not in use. When the input tray <NUM> is closed the footprint of the medium transport system <NUM> can be reduced. The input tray <NUM> allows hardcopy media <NUM> to be scanned to be placed into it. Examples of the hardcopy media are paper documents, photographic film, and magnetic recording media. Other examples of the hardcopy media <NUM> will be evident to those skilled in the art. The top hardcopy medium <NUM> is the medium at the top of the hardcopy media <NUM> and is the next document to be pulled into the scanner by the urging roller <NUM>. The input tray <NUM> is provided with input side guides 130a and 130b which can be moved in a direction perpendicular to a transport direction of the hardcopy media <NUM>. By positioning the side guides 130a and 130b to match with the width of the hardcopy media <NUM>, it is possible to limit the movement of the hardcopy media <NUM> in the input tray <NUM> as well as set the position (left, right or center justified) of the top hardcopy medium <NUM> within the media transport path. The input side guides 130a and 130b may be referred to collectively as the input side guides <NUM>. The input tray <NUM> may be attached to a motor (not shown) that causes the input tray <NUM> to raise top hardcopy medium <NUM> to the urging roller <NUM> for scanning or to lower the input tray <NUM> to allow additional hardcopy media <NUM> to be added to the input tray <NUM>.

The output tray <NUM> is connected to the scanner pod <NUM> by hinges, allowing the angle of the output tray <NUM> to be adjusted as shown by the arrow marked A1. The output tray <NUM> is provided with output side guides 160a and 160b which can be moved in a direction perpendicular to a transport direction of the hardcopy media <NUM>, that is, to the left and right directions from the transport direction of the hardcopy media <NUM>. By positioning the output side guides 160a and 160b to match with the width of the hardcopy media <NUM>, it is possible to limit the movement of the output hardcopy media <NUM> in the output tray <NUM>. The output side guides 160a and 160b may be referred to collectively as the output side guides <NUM>. An output tray stop <NUM> is provided to stop the top hardcopy medium <NUM> after being ejected from the output transport roller <NUM>. When the output tray <NUM> is in the up state as shown in <FIG>, the ejected hardcopy media is trail-edge aligned. In the down state, the ejected hardcopy media is lead-edge aligned against the output tray stop <NUM>.

The operator control panel <NUM> is attached to the scanner pod <NUM> and can be tilted as shown by the arrow marked A2 to allow optimal positioning for the operator. An operation input <NUM> is arranged on the surface of the operator control panel <NUM>, allowing the operator to input commands such as start, stop, and override. The operation input <NUM> may be one or more buttons, switches, portions of a touch-sensitive panel, selectable icons on a visual operator display <NUM>, or any other selectable input mechanism. The override command may allow the operator to temporarily disable multi-feed detection, jam detection, or other features of the scanner while scanning. The operator control panel <NUM> also includes an operator display <NUM> that allows information and images to be presented to the operator. As noted above, the display <NUM> could include selectable icons relating to commands and operations of the media transport device. The operator control panel <NUM> may also contain speakers and LEDs (not shown) to provide additional feedback to the operator.

<FIG> illustrates the transport path inside of the medium transport system <NUM>. The transport path inside of the medium transport system <NUM> has multiple rollers, including urging rollers <NUM>, feed rollers <NUM>, separator rollers <NUM>, take-away rollers <NUM>, transport rollers <NUM>, and an output transport roller <NUM>. The urging rollers <NUM> and feed roller <NUM> may be referred to collectively as the feed module <NUM>. Microphones 200a, 200b, 200c, a first media sensor <NUM>, a second media sensor <NUM>, an ultrasonic transmitter <NUM>, and an ultrasonic receiver <NUM> are positioned along the media transport path <NUM> to sense media and conditions within the media transport path <NUM> as the top hardcopy medium <NUM> is transported through the system. A pod image acquisition unit <NUM> and a base image acquisition unit <NUM> are included to capture images of the media.

The top surface of the scanner base <NUM> forms a lower media guide <NUM> of the media transport path <NUM>, while the bottom surface of the scanner pod <NUM> forms and upper media guide <NUM> of the media transport path <NUM>. A delta wing <NUM> may be provided which helps to guide the media from the input tray into the media transport path <NUM>. As shown in <FIG>, the delta wing may be a removable section of the upper media guide <NUM>, transitioning from the upper media guide <NUM> to the scanner cabinetry of the pod <NUM>. The delta wing may be angled to allow microphones <NUM> A, B to point into the input tray <NUM>, thereby improving signal pickup.

In <FIG>, the arrow A4 shows the transport direction that the hardcopy media travels within the media transport path <NUM>. As used herein, the term "upstream" refers a position relative to the transport direction A4 that is closer to the input tray <NUM>, while "downstream" refers to a position relative to the transport direction A4 that is closer to the output tray <NUM>. The first media sensor <NUM> has a detection sensor which is arranged at an upstream side of the urging roller <NUM>. The first media sensor <NUM> may be mounted within the input tray <NUM>, and detects if a hardcopy media <NUM> is placed on the input tray <NUM>. The first media detector <NUM> can be of any form known to those skilled in the art including, but not limited to, contact sensors and optical sensors. The first media sensor <NUM> generates and outputs a first media detection signal which changes in signal value depending on whether or not media is placed on the input tray <NUM>.

The first microphone 200a, second microphone 200b, and third microphone 200c are examples of sound detectors that detect the sound generated by the top hardcopy medium <NUM> during transport through the media transport path <NUM>. The microphones generate and output analog signals representative of the detected sound. The microphones 200a and 200b are arranged to the left and right of the urging rollers <NUM> while fastened to the delta wing <NUM> at the front of the scanner pod <NUM>. The microphones 200a and 200b are mounted so as to point down towards the input tray <NUM>. To enable the sound generated by the top hardcopy medium <NUM> during transport of the media to be more accurately detected by the first microphone 200a and the second microphone 200b, a hole is provided in the delta wing <NUM> facing the input tray <NUM>. The microphones 200a and 200b are mounted to the delta wing <NUM> using a vibration reducing gasket. The third microphone 200c is at the downstream side of the feed roller <NUM> and the separator roller <NUM> while fastened to the upper media guide <NUM>. A hole for the third microphone 200c is provided in the upper media guide <NUM> facing media transport path <NUM>. The microphone 200c is mounted in the upper media guide <NUM> using a vibration reducing gasket. As an example, the microphones may be MEMS microphones mounted flush to a baffle with isolator material to reduce vibration transferring from the baffle to the MEMS. By mounting the MEMS flush, the amount of internal machine noise behind the microphone that can be detected by the microphone is reduced.

The second media detector <NUM> is arranged at a downstream side of the feed roller <NUM> and the separator roller <NUM> and at an upstream side of the take-away rollers <NUM>. The second media detector <NUM> detects if there is a hardcopy media present at that position. The second media detector <NUM> generates and outputs a second media detection signal which changes in signal value depending on whether hardcopy media is present at that position. The second media detector <NUM> can be of any form known to those skilled in the art including, but not limited to, contact sensors, motion sensor and optical sensors.

The ultrasonic transmitter <NUM> and the ultrasonic receiver <NUM>, together forming an ultrasonic sensor <NUM>, are arranged near the media transport path <NUM> of the top hardcopy medium <NUM> so as to face each other across the media transport path <NUM>. The ultrasonic transmitter <NUM> transmits an ultrasonic wave that passes through the top hardcopy medium <NUM> and is detected by the ultrasonic receiver <NUM>. The ultrasonic receiver then generates and outputs a signal, which may be an electrical signal, corresponding to the detected ultrasonic wave.

A plurality of ultrasonic transmitters <NUM> and ultrasonic receivers <NUM> may be used. In this situation, the ultrasonic transmitters <NUM> are positioned across the lower media guide <NUM> perpendicular to the transport direction as marked by arrow A4 while ultrasonic receivers <NUM> are positioned across the upper media guide <NUM> perpendicular to the transport direction as marked by arrow A4.

The pod image acquisition unit <NUM> has an image sensor, such as a CIS (contact image sensor) or CCD (charged coupled device). Similarly, the base image acquisition unit <NUM> has an image sensor, such as a CIS or CCD.

As the top hardcopy medium <NUM> travels through the media transport path <NUM>, it passes the pod imaging aperture <NUM> and the base imaging aperture <NUM>. The pod imaging aperture <NUM> is a slot in the upper media guide <NUM> while the base imaging aperture <NUM> is a slot in the lower media guide <NUM>. The pod image acquisition unit <NUM> images the top surface of the top hardcopy medium <NUM> as it passes the pod imaging aperture <NUM> and outputs an image signal. The base image acquisition unit <NUM> images the bottom surface of the top hardcopy medium <NUM> as it passes the base imaging aperture <NUM> and outputs an image signal. It is also possible to configure the pod image acquisition unit <NUM> and the base image acquisition unit <NUM> such that only one surface of the top hardcopy medium <NUM> is imaged.

The top hardcopy medium <NUM> is moved along a media transport path <NUM> by sets of rollers. The sets of rollers are composed of a drive roller and normal force roller. The drive roller is driven by a motor which provides the driving force to the roller. The normal force roller is a freewheeling roller that provides pressure to capture the top hardcopy medium <NUM> between the drive roller and normal force roller. In the medium transport system <NUM>, the initial drive and normal force rollers that grab the top hardcopy medium <NUM> within the media transport path <NUM> are referred to as take-away rollers <NUM>. The additional drive and normal force roller pairs along the media transport path <NUM> are referred to as transport rollers <NUM>. The roller may be driven by a single motor where all the rollers start and stop together. Alternatively the rollers may be grouped together where each group is driven by its own motor. This allows different motor groups to be started and stopped at different times or run at different speeds.

The medium transport system <NUM> may have an output transport roller <NUM>. The output transport roller <NUM> is connected to a separate drive motor that either speeds-up the top hardcopy medium <NUM> or slows down the top hardcopy medium <NUM> for modifying the way the output hardcopy media <NUM> is placed into the output tray <NUM>, as described in detail in <CIT>.

Hardcopy media <NUM> placed on the input tray <NUM> is transported between the lower media guide <NUM> and the upper media guide <NUM> in the transport direction shown by arrowA4 by rotation of the urging roller <NUM>. The urging roller <NUM> pulls the top hardcopy medium <NUM> out of the input tray <NUM> and pushes it into the feed roller <NUM>. The separator roller <NUM> resists the rotation of the feed roller <NUM> such that when the input tray <NUM> has a plurality of hardcopy media <NUM> placed on it, only the top hardcopy medium <NUM> which is in contact with the feed roller <NUM> is selected for feeding into the media transport path <NUM>. The transport of the hardcopy media <NUM> below the top hardcopy medium <NUM> is restricted by the separator roller <NUM> to prevent feeding more than one medium at a time which is referred to as a multi-feed.

The top hardcopy medium <NUM> is fed between the take-away rollers <NUM> and is transported through the transport rollers <NUM> while being guided by the lower media guide <NUM> and the upper guide <NUM>. The top hardcopy medium <NUM> is sent past the pod image acquisition unit <NUM> and the base image acquisition unit <NUM> for imaging. The top hardcopy medium <NUM> is then ejected into the output tray <NUM> by the output transport roller <NUM>. In addition to microphones 200a, 200b, and 200c, a microphone <NUM> may be provided near the exit of the transport path. This microphone <NUM> detects the sounds of the hardcopy media towards the end of the transport path, and as the media is output into the output tray <NUM>. These detected sounds may be used to detect jams occurring in the output tray <NUM> or as documents are exiting the media transport device. A system processing unit <NUM> monitors the state of the medium transport system <NUM> and controls the operation of the medium transport system <NUM> as described in more detail below.

Although <FIG> shows the urging roller <NUM> above the stack of hardcopy media <NUM> to select the top hardcopy media <NUM>, in a feeding configuration often referred to as a top feeding mechanism, other configurations may be used. For example, the urging roller <NUM>, feed roller <NUM> and separator roller <NUM> can be inverted such that the urging roller select the hardcopy media at the bottom of the hardcopy media stack <NUM>. In this configuration microphone 200a and 200b may be moved into the scanner base <NUM>.

<FIG> is a block diagram of the medium transport system <NUM> as seen from the viewpoint shown by the direction arrow A5 in <FIG>. As shown in <FIG>, the first microphone 200a is provided to the left of the urging roller <NUM> and feed rollers <NUM> along the delta wing <NUM>. The second microphone 200b is provided to the right of the urging roller <NUM> and feed rollers <NUM> along the delta wing. The placement of microphones 200a and 200b capture sound from the top hardcopy medium <NUM> as it is being urged into the feed roller <NUM> by the urging roller <NUM>. The third microphone 200c is preferably located slightly behind and downstream of the feed rollers <NUM>. The placement of microphone 200c captures sound from the top hardcopy medium <NUM> as it passes the feed roller <NUM> and before reaching the take-away rollers <NUM>.

<FIG> is an example of a block diagram which shows the schematic illustration of a medium transport system <NUM>. The pod image acquisition unit <NUM> is further composed of a pod image device <NUM>, pod image A/D converter <NUM> and pod pixel correction <NUM>. As noted above, the pod image device <NUM> has a CIS (contact image sensor) of an equal magnification optical system type which is provided with an image capture element using CMOS (complementary metal oxide semiconductors) which are arranged in a line in the main scan direction which is perpendicular to the media transport path <NUM> as shown by arrow A4. As noted above, instead of a CIS, it is also possible to utilize an image capturing sensor of a reduced magnification optical system type using CCD's (charge coupled devices). The pod imaging A/D converter <NUM> converts an analog image signal which is output from the pod image device <NUM> to generate digital image data which is then output to the pod pixel correction <NUM>. The pod pixel correction <NUM> corrects for any pixel or magnification abnormalities. The pod pixel correction <NUM> outputs the digital image data to the image controller <NUM> within the system processing unit <NUM>. The base image acquisition unit <NUM> is further composed of a base image device <NUM>, base image A/D converter <NUM> and base pixel correction <NUM>. The base image device <NUM> has a CIS (contact image sensor) of an equal magnification optical system type which is provided with an image capture element using CMOS's (complementary metal oxide semiconductors) which are arranged in a line in the main scan direction. As noted above, instead of a CIS, it is also possible to utilize an image capturing sensor of a reduced magnification optical system type using CCD's (charge coupled devices). The base imaging A/D converter <NUM> converts an analog image signal which is output from the base image device <NUM> to generate digital image data which is then output to the base pixel correction <NUM>. The base pixel correction <NUM> corrects for any pixel or magnification abnormalities. The base pixel correction <NUM> outputs the digital image data to the image controller <NUM> within the system processing unit <NUM>. Digital image data from the pod image acquisition unit <NUM> and the base image acquisition unit <NUM> will be referred to as captured images.

The operator configures the image controller <NUM> to perform the required image processing on the captured images either through the operator control panel <NUM> or network interface <NUM>. As the image controller <NUM> receives the captured images, it sends the captured images to the image processing unit <NUM> along with a job specification that defines the image processing that should be performed on the captured images. The image processing unit <NUM> performs the requested image processing on the captured images and outputs processed images. It will be understood that the functions of image processing unit <NUM> can be provided using a single programmable processor or by using multiple programmable processors, including one or more digital signal processor (DSP) devices. Alternatively, the image processing unit <NUM> can be provided by custom circuitry (e.g., by one or more custom integrated circuits (ICs) designed specifically for use in digital document scanners), or by a combination of programmable processor(s) and custom circuits.

The image controller <NUM> manages image buffer memory <NUM> to hold the processed images until the network controller <NUM> is ready to send the processed images to the network interface <NUM>. The image buffer memory <NUM> can be internal or external memory of any form known to those skilled in the art including, but not limited to, SRAM, DRAM, or Flash memory. The network interface <NUM> can be of any form known to those skilled in the art including, but not limited to, Ethernet, USB, Wi-Fi or other data network interface circuit. The network interface <NUM> connects the medium transport system <NUM> with a computer or network (not shown) to send and receive the captured image. The network interface <NUM> also provides a means to remotely control the medium transport system <NUM> by supplying various types of information required for operation of the medium transport system <NUM>. The network controller <NUM> manages the network interface <NUM> and directs network communications to either the image controller <NUM> or a machine controller <NUM>.

A first sound acquisition unit 420a includes the first microphone 200a, a first sound analog processing 422a, and a first sound A/D Converter 424a, and generates a sound signal responsive to the sound picked up by the first microphone 200a. The first sound analog processing 422a filters the signal which is output from the first microphone 200a by passing the signal through a low-pass or band-pass filter to select the frequency band of the interest. The first sound analog processing 422a also amplifies the signal and outputs it to the first sound A/D converter 424a. The first sound A/D converter 424a converts the analog signal which is output from the first sound analog processing 422a to a digital first source signal and outputs it to the system processing unit <NUM>. As described herein, outputs of the first sound acquisition unit 420a are referred to as the "left sound signal". The first sound acquisition unit 420a may comprise discrete devices or may be integrated into a single device such as a digital output MEMS microphone.

A second sound acquisition unit 420b includes the second microphone 200b, a second sound analog processing 422b, and a second sound A/D Converter 424b, and generates a sound signal responsive to the sound picked up by the second microphone 200b. The second sound analog processing 422b filters the signal which is output from the second microphone 200b by a passing the signal through a low-pass or band-pass filter to select the frequency band of the interest. The second sound analog processing 422b also amplifies the signal and outputs it to the second sound A/D converter 424b. The second sound A/D converter 424b converts the analog signal which is output from the second sound analog processing 422b to a digital second source signal and outputs it to the system processing unit <NUM>. As described herein, outputs of the second sound acquisition unit 420b outputs will be referred to as the "right sound signal". The second sound acquisition unit 420b may comprise discrete devices or may be integrated into a single device such as a digital output MEMS microphone.

A third sound acquisition unit 420c includes the third microphone 200c, a third sound analog processing 422c, and a third sound A/D Converter 424c, and generates a sound signal responsive to the sound picked up by the third microphone 200c. The third sound analog processing 422c filters the signal which is output from the third microphone 200c by a passing the signal through a low-pass or band-pass filter to select the frequency band of the interest. The third sound analog processing 422c also amplifies the signal and outputs it to the third sound A/D converter 424c. The third sound A/D converter 424c converts the analog signal which is output from the third sound analog processing 422c to a digital third source signal and outputs it to the system processing unit <NUM>. As described herein, outputs of the third sound acquisition unit 420c outputs will be referred to as the "center sound signal ". The third sound acquisition unit 420c may comprise discrete devices or may be integrated into a single device such as a digital output MEMS microphone.

Below, the first sound acquisition unit 420a, second sound acquisition unit 420b and the third sound acquisition unit 420c may be referred to overall as the sound acquisition unit <NUM>.

The transport driver unit <NUM> includes one or more motors and control logic required to enable the motors to rotate the urging roller <NUM>, the feed roller <NUM>, the take-away rollers <NUM>, and the transport rollers <NUM> to transport the top hardcopy medium <NUM> through the media transport path <NUM>.

The system memory <NUM> has a RAM (random access memory), ROM (read only memory), or other memory device, a hard disk or other fixed disk device, or flexible disk, optical disk, or other portable storage device. Further, the system memory <NUM> stores a computer program, database, and tables, which are used in various control function of the medium transport system <NUM>. Furthermore, the system memory <NUM> may also be used to store the captured images or processed images.

The system processing unit <NUM> is provided with a CPU (central processing unit) and operates based on a program which is stored in the system memory <NUM>. The system processing unit <NUM> may be a single programmable processor or may be comprised of multiple programmable processors, a DSP (digital signal processor), LSI (large scale integrated circuit), ASIC (application specific integrated circuit), and/or FPGA (field-programming gate array). The system processing unit <NUM> is connected to the operator button <NUM>, the operator display <NUM>, first media sensor <NUM>, second media sensor <NUM>, ultrasonic sensor <NUM>, pod image acquisition unit <NUM>, base image acquisition unit <NUM>, first sound acquisition unit 420a, second sound acquisition unit 420b, third sound acquisition unit 420c, image processing unit <NUM>, image buffer memory <NUM>, network interface <NUM>, system memory <NUM>, transport driver unit <NUM>.

The system processing unit <NUM> controls the transport driver unit <NUM>, controls the pod image acquisition unit <NUM> and base image acquisition unit <NUM> to acquire a captured image. Further, the system processing unit <NUM> has a machine controller <NUM>, an image controller <NUM>, a sound jam detector <NUM>, a position jam detector <NUM>, and a multi-feed detector <NUM>. These units are functional modules which are realized by software operating on a processor. These units may also be implemented on independent integrated circuits, a microprocessor, DSP or FPGA.

The sound jam detector <NUM> executes the sound jam detection processing. In the sound jam detection processing, the sound jam detector <NUM> determines whether a jam has occurred based on a first sound signal acquired from the first sound acquisition unit 420a, a second sound signal acquired from the second sound acquisition unit 420b and/or a third sound signal acquired from the third sound acquisition unit 420c. Situations in which the sound jam detector <NUM> determines that a media jam has occurred based on each signal, or a combination of signals, may be referred to as a sound jam.

The position jam detector <NUM> executes the position jam detection processing. The position jam detector <NUM> uses second media detection signals acquired from the second media sensor <NUM>, an ultrasonic detection signal acquired from the ultrasonic detector <NUM> and a timer unit <NUM>, started when the transport driver unit <NUM> enables the urging rollers <NUM> and the feed rollers <NUM> to feed the top hardcopy medium <NUM>, to determine whether a jam has occurred. The position jam detector <NUM> can also use pod image acquisition unit <NUM> and base image acquisition unit <NUM> to detect the lead-edge and trail-edge of the top hardcopy media <NUM>. In this case the image controller <NUM> outputs a lead-edge and trail-edge detection signal which is combined with the timer unit <NUM> to determine whether a jam has occurred if the lead-edge and trail-edge detection signal are not asserted within a predefined amount of time. Situations in which the position jam detector <NUM> determines that a media jam has occurred based on the second media detection signal, the ultrasonic detection signal, pod image acquisition unit <NUM> or base image acquisition unit <NUM> may be referred to as a position jam.

The multi-feed detector <NUM> executes multi-feed detection processing. In the multi-feed detection processing, the multi-feed detector <NUM> determines whether the feed module <NUM> has allowed multiple hardcopy media to enter the media transport path <NUM> based on an ultrasound signal acquired from the ultrasonic detector <NUM>. Situations in which the multi-feed detector <NUM> determines that multiple hardcopy media entered the media transport path <NUM> may be referred to as a multi-feed.

The machine controller <NUM> determines whether an abnormality condition, such as a medium jam, has occurred along a media transport path <NUM>. The machine controller <NUM> determines that an abnormality has occurred when there is at least one of a sound jam, a position jam, and/or a multi-feed condition. When an abnormality is detected, the machine controller <NUM> takes action based on the operators predefined configuration for abnormality conditions. One example of a predefined configuration would be for the machine controller <NUM> to inform the transport driver unit <NUM> to disable the motors. At the same time, the machine controller <NUM> notifies the user of media jam using the operator control panel <NUM>.

When a medium jam along a media transport path <NUM> has not occurred, the image controller <NUM> causes the pod imaging acquisition unit <NUM> and the base imaging acquisition unit <NUM> to image the top hardcopy medium <NUM> to acquire a captured image. The pod imaging acquisition unit <NUM> images the top hardcopy medium <NUM> via the pod image device <NUM>, pod image A/D Converter <NUM>, and pod pixel correction <NUM> while the base imaging acquisition unit <NUM> images the top hardcopy medium <NUM> via the base image device <NUM>, base image A/D converter <NUM>, and base pixel correction <NUM>.

<FIG> is a block diagram of the processing for a preferred embodiment of the present invention. Microphone 200a detects the sound produced by the top hardcopy medium <NUM> along the left side of the media transport path <NUM> and first sound acquisition unit 420a produces signal A <NUM> representing the sound at that microphone. Microphone 200b detects the sound produced by the top hardcopy medium <NUM> along right side the media transport path <NUM> and second sound acquisition unit 420b produces signal B <NUM> representing the sound at that microphone. Microphone 200c detects the sound produced by the top hardcopy medium <NUM> along the center of the media transport path <NUM> and third sound acquisition unit 420c produces signal C <NUM> representing the sound at that microphone. Microphone 200a, 200b and 200c can be of any form of sensors known to those skilled in the art including, but not limited to, electromagnetic induction sensors, capacitance change sensors, and/or piezoelectric sensors. System Processing Unit <NUM> produces sound values A550 from signal A <NUM>; signal values B <NUM> from signal B <NUM> and sound values C <NUM> from the signal C <NUM> which are produced by the sound acquisition unit <NUM>.

<FIG> is an example of a set of sound values produced by a normal passage of the top hardcopy medium <NUM> along the media transport path <NUM> at microphone 200a, microphone 200b and microphone 200c. Collectively the sound values A <NUM> represent the sound profile A <NUM> of the top hardcopy medium <NUM> captured at microphone 200a position. Collectively the sound values B <NUM> represent the sound profile B <NUM> of the top hardcopy medium <NUM> captured at microphone 200b position. Collectively the sound values C <NUM> represent the sound profile C <NUM> of the top hardcopy medium <NUM> captured at microphone 200c position.

Detection of the sound of the top hardcopy medium <NUM> begins at points <NUM>, <NUM> and <NUM> in <FIG> by the microphones 200a, 200b and 200c respectively. Points <NUM>, <NUM> and <NUM> mark the start of Region A in <FIG> and corresponds to the machine controller <NUM> activating the transport driver unit <NUM> to activate the urging roller <NUM> to pull the top hardcopy medium <NUM> towards the feed roller <NUM> and the separator roller <NUM>. Region A represents the sound values captured in the delay between the machine controller <NUM> activating the transport driver unit <NUM> and the rollers actually rotating. Region B in <FIG> corresponds to the urging roller <NUM> going from being stationary to rotating and pulling the top hardcopy medium <NUM> into the feed roller <NUM> and the separator roller <NUM>. The duration of region B is defined by the amount of time for the roller noise to dissipate into the background of the noise from the top hardcopy medium <NUM>. Region C in <FIG> corresponds to the top hardcopy medium <NUM> being selected and pushed towards the take-away roller <NUM>. At the end of region C, the top hardcopy medium <NUM> is at the ultrasonic detector <NUM>. Region D in <FIG> corresponds to the top hardcopy media <NUM> after it passes the take-away roller <NUM> and ends when the transport driver unit <NUM> de-activates the feed module <NUM> to prevent additional hardcopy media <NUM> from entering the media transport path <NUM>. The separator roller <NUM> resists the feeding of addition hardcopy media <NUM>, if present, and the next hardcopy media <NUM> to come to the top of the media stack in the input tray <NUM> is pre-staged at the separator roller <NUM>. Region E in <FIG> corresponds to the top hardcopy medium <NUM> in the media transport path <NUM> after the feed module <NUM> is de-activated. Additional regions could be created by using additional sensors such as the second media sensor <NUM> to determine the location of the top hardcopy medium <NUM> within the media transport path <NUM>.

A sound jam detection window is used to define the region(s) of sound values in sound profiles shown in <FIG> where the sound jam detector <NUM> executes the sound jam detection processing on the sound values looking for a sound jam. <FIG> is a flowchart of a sound jam detection processing portion of the preferred embodiment of the present invention. A compute maximum loudness block <NUM> produces loudness A <NUM> from the sound values A <NUM>. A compute maximum loudness block <NUM> produces loudness B <NUM> from the sound values B <NUM>. A compute maximum loudness block <NUM> produces loudness C <NUM> from the sound values C <NUM>. A jam test block <NUM> tests the loudness A <NUM>, loudness B <NUM> and loudness C <NUM> and produces a YES result and indicates a jam <NUM> if a medium jam is detected or a NO result if no jam is detected. The medium transport system continues operation <NUM> if a medium jam is not detected. Examples of a medium jam are stoppages of medium movement along the media transport path <NUM>, multiple hardcopy media <NUM> being simultaneously fed into a media transport path <NUM> designed to convey only single medium of hardcopy media <NUM> at one time, and wrinkling, tearing, or other physical damage to the hardcopy media <NUM>.

In <FIG> the compute maximum loudness block <NUM> computes loudness A <NUM> which represents how much sound was produced or the intensity of sound produced from sound values A <NUM>. The loudness A <NUM> can be computed by a high amplitude count from the sounds values A <NUM>, as described in <CIT>. The loudness A <NUM> can be represented by, for example, the maximum peak-to-peak amplitude or peak amplitude of the sound values A <NUM>. The loudness A <NUM> may also be represented by any other comparison of characteristics or qualities of sound values A <NUM>. A moving window may be used to partition the sound values A into frames that are collectively used together in the compute maximum loudness block <NUM>. The moving window computes loudness A <NUM> from the most recent N<NUM> sound values A <NUM> within the jam detection region for sound profile A <NUM> where N<NUM> is typically <NUM>. The compute maximum loudness block <NUM> begins at <NUM> and continues until a medium jam is detected or the end of the sound values A <NUM> has been reached or the end of the jam detection window is reached. When the urging roller <NUM> and feed roller <NUM> initially start rotating, they produce a spike or burst of noise, as shown in region B of the sound profile A <NUM>. This spike is referred to as mechanical noise and is due to the mechanical parts of the urging roller <NUM> and feed roller <NUM> going from stationary to a rotating motion. The compute maximum loudness block <NUM> ignores the sound values A <NUM> within region A or region B of the sound profile A <NUM> to avoid producing a false jam based on the mechanical noise. Alternatively the compute maximum loudness block <NUM> may weight the sound values A <NUM> within region A or region B of the sound profile A <NUM> to reduce the chance of producing a false jam.

The compute maximum loudness block <NUM> computes loudness B <NUM> which represents how much sound was produced or the intensity of sound produce from sound values B <NUM>. The loudness B <NUM> can be computed by a high amplitude count from the sounds values B <NUM>, as described in <CIT>. The loudness B <NUM> can be represented by, for example, the maximum peak-to-peak amplitude or peak amplitude of the sound values B <NUM>. The loudness B <NUM> may also be represented by any other comparison of characteristics or qualities of sound values B <NUM>. A moving window may be used to partition the sound values B into frames that are collectively used together in the compute maximum loudness block <NUM>. The moving window computes loudness B <NUM> from the most recent N<NUM> sound values B <NUM> within the jam detection region for sound profile B <NUM> where N<NUM> is typically <NUM>. The compute maximum loudness block <NUM> begins at <NUM> and continues until a medium jam is detected or the end of the sound values B <NUM> has been reached or the end of the jam detection window is reached. When the urging roller <NUM> and feed roller <NUM> initial start rotating, they produce a spike of noise, as shown in region B of the sound profile B <NUM>. This spike is referred to as mechanical noise and is due to the mechanical parts of the urging roller <NUM> and feed roller <NUM> going from stationary to a rotating motion. The compute maximum loudness block <NUM> ignores the sound values B <NUM> within region A or region B of the sound profile B <NUM> to avoid producing a false jam based on the mechanical noise. Alternatively the compute maximum loudness block <NUM> may weight the sound values B <NUM> within region A or region B of the sound profile B <NUM> to reduce the chance of producing a false jam.

The compute maximum loudness block <NUM> computes loudness C <NUM> which represents how much sound was produced or intensity of sound produce from sound values C <NUM>. The loudness C <NUM> can be computed by a high amplitude count from the sounds values C <NUM>, as described in <CIT>. The loudness C <NUM> can be represented, for example, by the maximum peak-to-peak amplitude or peak amplitude of the sound values C <NUM>. The loudness C <NUM> may also be represented by any other comparison of characteristics or qualities of sound values C <NUM>. A moving window may be used to partition the sound values C into frames that are collectively used together in the compute maximum loudness <NUM>. The moving window computes loudness C <NUM> from the most recent N<NUM> sound values C <NUM> within the jam detection region for sound profile C <NUM> where N<NUM> is typically <NUM>. The compute maximum loudness block <NUM> begins at <NUM> and continues until a medium jam is detected or the end of the sound values C <NUM> has been reached or the end of the jam detection window is reached. When the urging roller <NUM> and feed roller <NUM> initial start rotating, they produce a spike of noise, as shown in region B of the sound profile C <NUM>. This spike is referred to as mechanical noise and is due to the mechanical parts of the urging roller <NUM> and feed roller <NUM> going from stationary to a rotating motion. The compute maximum loudness block <NUM> ignores the sound values C <NUM> within region A or region B of the sound profile C <NUM> to avoid producing a false jam based on the mechanical noise. Alternatively the compute maximum loudness block <NUM> may weight the sound values C <NUM> within region A or region B of the sound profile A <NUM> to reduce the chance of producing a false jam.

It should be noted that compute maximum loudness block <NUM>, <NUM> and <NUM> do not have to use the same method to compute the loudness of the sound values <NUM>, <NUM> and <NUM>. A different method may be used for each microphone.

<FIG> is a detailed diagram of the jam test block <NUM>. Block <NUM> compares the loudness value A <NUM> to loudness threshold TA1. If the loudness A <NUM> is greater than the loudness threshold TA1, a jam <NUM> is indicated. If the loudness value A <NUM> is not greater than the threshold TA1 then the jam test moves to block <NUM> which compares the loudness value B <NUM> to loudness threshold TB1.

If the loudness value B <NUM> is greater than the loudness threshold TB1, a jam <NUM> is indicated. If the loudness value B <NUM> is not greater than the loudness threshold TB1 then the jam test moves to block <NUM> which compares the loudness value C <NUM> to loudness threshold TC1.

If the loudness value C <NUM> is greater than the loudness threshold TC1, a jam <NUM> is indicated. If the loudness value C <NUM> is not greater than the loudness threshold TC1 then the jam test moves to block <NUM> which compares the loudness value A <NUM> to loudness threshold TA21 and compares the loudness value B <NUM> to loudness threshold TB21.

If the loudness value A <NUM> is greater than the loudness threshold TA21 and loudness value B <NUM> is greater than loudness threshold TB21, a jam <NUM> is indicated. If the loudness value A <NUM> is not greater than the loudness threshold TA21, or loudness value B <NUM> is not greater than the loudness threshold TB21 then the jam test moves to block <NUM> which compares the loudness value A <NUM> to loudness threshold TA22 and loudness value C <NUM> to loudness threshold TC22.

If the loudness value A <NUM> is greater than the loudness threshold TA22 and loudness value C <NUM> is greater than loudness threshold TC22, a jam <NUM> is indicated. If the loudness value A <NUM> is not greater than the loudness threshold TA22, or loudness value C <NUM> is not greater than the loudness threshold TC22, then the jam test moves to block <NUM> which compares the loudness value B <NUM> to loudness threshold TB23 and loudness value C <NUM> to loudness threshold TC23.

If the loudness value B <NUM> is greater than the loudness threshold TB23 and loudness value C <NUM> is greater than loudness threshold TC23, a jam <NUM> is indicated. If the loudness value B <NUM> is not greater than the loudness threshold TB23, or loudness value C <NUM> is not greater than the loudness threshold TC23 then the jam test moves to block <NUM> which compares the loudness value A <NUM> to loudness threshold TA3, loudness value B <NUM> to loudness threshold TB3 and loudness value C <NUM> to loudness threshold TC3.

If the loudness value A <NUM> is greater than the loudness threshold TA3 and loudness value B <NUM> is greater than loudness threshold TB3, and loudness value C <NUM> is greater than loudness threshold TC3, a jam <NUM> is indicated. If the loudness value A <NUM> is not greater than the loudness threshold TA3, or the loudness value B <NUM> is not greater than the loudness threshold TB3, or the loudness value C <NUM> is not greater than the loudness threshold TC3 then the jam test moves to continue <NUM>.

In a document scanner, many jams are the result of poor preparation where the operator does not ensure that the multiple hardcopy media <NUM> are attached together before it is placed into the input tray <NUM>. The hardcopy media <NUM> can be attached together with staples, paper clips or adhesive. Other examples of how the hardcopy media <NUM> can be attached together will be evident to those skilled in the art.

A hardcopy media jam is most likely to occur when the top hardcopy medium <NUM> is being selected from the stack of hardcopy media <NUM> in the input tray <NUM> by the feed module <NUM> and is being fed into the media transport path <NUM> by the feed roller <NUM>. During this time the third microphone 200c is ideally positioned for detecting a media jam behind the feed roller <NUM>. Once the lead-edge of the top hardcopy medium <NUM> passes the take-away roller <NUM> the probability of a media jam is reduced. As the trail-edge of the top hardcopy medium <NUM> approaches urging roller <NUM> the chance of a trail-edge jam begin increasing. During this time the first microphone 200a and the second microphone 200b are ideally positioned for detecting a media jam along the trail-edge of the top hardcopy medium <NUM>.

As the trail-edge of a hardcopy media passes the feed module <NUM>, the trail edge of the hardcopy media may make a snapping sound that creates a sharp impulse in the sound signal value C <NUM>. This sharp impulse may be referred to as the trail-edge snap. To reduce the probability of false jam detection on the trail-edge, the compute maximum loudness block <NUM> favors regions A, B and C of the sound profile C <NUM> while weighting the sound values C <NUM> from the other regions less. This effectively creates a low sensitivity region as the top hardcopy medium <NUM> is transported though the media transport path <NUM>. The compute maximum loudness blocks <NUM> and <NUM> favor regions C, D and E of the sound profile A <NUM> and sound profile B <NUM> which allows trail-edge media jams to be detected without increasing the risk of false jams due the trail-edge snap as it passes over the point of feeding at the contact between feed rollers <NUM> and the separator rollers <NUM>.

<FIG> shows the top hardcopy media <NUM> attached on the lead-edge to the next hardcopy medium <NUM> by staple <NUM>. When the top hardcopy media <NUM> is attached on the lead-edge with a staple, for example, the urging roller <NUM> pulls the top hardcopy medium <NUM> off the stack of the hardcopy media <NUM> in the input tray <NUM>. The feed roller <NUM> pulls the top hardcopy medium <NUM> into the media transport path while the separator roller <NUM> prevents the next hardcopy medium <NUM> from entering the media transport path. Since the top hardcopy medium <NUM> is attached to the next hardcopy medium <NUM> on the lead-edge, the next hardcopy medium <NUM> starts to be pulled into the media transport path <NUM> at the point where the staple <NUM> attaches the top hardcopy medium <NUM> to the next hardcopy medium <NUM>. At the same time separator roller <NUM> is applying force to the next hardcopy media <NUM> in the opposite direction. This opposite force causes the top hardcopy medium <NUM> to buckle at the staple <NUM> and around the feed roller <NUM> as shown in <FIG> where the buckling is labeled B1. This buckling B1 of the top hardcopy medium <NUM> creates noise that is picked up by the microphone 200c. The bucking location of the top hardcopy medium <NUM> can be determined by checking the loudness detected by microphone 200a and 200b. If the top hardcopy medium <NUM> is stapled on the left then microphone 200a detects an increase in loudness. Likewise, if the staple is on the right then microphone 200b detects increase in loudness. If the buckling of the top hardcopy medium <NUM> is significant then microphone 200a or microphone 200b will detect the jam because microphone 200a or microphone 200b have a higher loudness value than microphone <NUM> C.

<FIG> shows top hardcopy media <NUM> attached on the trail-edge to the next hardcopy media <NUM> by staple <NUM>. When the top hardcopy media <NUM> is attached on the trail-edge with a staple, for example, the urging roller <NUM> pulls the top hardcopy medium <NUM> off the stack of the hardcopy media <NUM> in the input tray <NUM>. The feed roller <NUM> pulls the top hardcopy medium <NUM> into the media transport path <NUM> while the separator roller <NUM> prevents the next hardcopy media <NUM> from entering the media transport path <NUM>. The top hardcopy media <NUM> slides over the next hardcopy media <NUM> as it enters the media transport path <NUM>.

Since the top hardcopy medium <NUM> is attached to the next hardcopy media <NUM> on the trail-edge, the trail-edge of the top hardcopy medium <NUM> starts to pull the trail-edge of the next hardcopy media <NUM> towards the media transport path <NUM>. This has the effect of lifting up the trail-edge of the top hardcopy medium <NUM> and the next hardcopy media <NUM> at the staple <NUM>. As top hardcopy medium <NUM> is pulled further into the media transport path <NUM> the trail-edge of top hardcopy medium <NUM> and the next hardcopy media <NUM> at the staple <NUM> strikes the delta wing at labeled B2 as shown in <FIG> causing a sound to be picked up by microphone 200a or microphone 200b. The location staple <NUM> can be determined by the microphone that detected the jam. Typically if the staple is on the left then microphone 200a detects the jam. Likewise, if the staple is on the right then microphone 200b detects the jam.

The distance that the lead-edge of the top hardcopy medium <NUM> travels into the media transport path <NUM> and the distance the staple is located from the lead-edge can be determined by monitoring the second media sensor <NUM> along with the ultrasonic sensor <NUM>. This can be used to provide additional information regarding how the top hardcopy medium <NUM> is bound to the hardcopy media below it. For example, if the trail-edge of top hardcopy medium <NUM> is attached to the next hardcopy media <NUM> then the machine controller <NUM> could signal the transport driver unit <NUM> to reverse the motors to so that rollers return the top hardcopy medium <NUM> and the next hardcopy media <NUM> to the input tray <NUM>.

Over time the sound profiles <NUM>, <NUM>, <NUM> as shown in <FIG> change as the mechanical components of the medium transport system <NUM> wear. For example, the sound profiles may become louder as the parts wear and generate more noise within the medium transport system. When this occurs, the system may provide an audible or visual alert to the operator that maintenance or replacement of parts may be required. To detect or compensate for additional noise introduced by mechanical components, a calibration procedure can be implemented within the medium transport system <NUM>. In region A of sound profiles <NUM>, <NUM>, <NUM>, the urging roller <NUM> has not started to urge the top hardcopy medium <NUM> into the feed roller <NUM>. The sound values A <NUM>, B <NUM>, and C <NUM> within region A of <FIG> are used detect any changes in the mechanical components of the medium transport system <NUM> as well as changes in the microphone sound pickup. In an alternative, the gap between two consecutive top hardcopy medium <NUM> could be used. In this case, the sound values A <NUM>, B <NUM>, and C <NUM> can be used after the trail-edge of the top hardcopy medium <NUM> has passed the first media sensor <NUM> as indicted by the first media detection signal.

<FIG> is an example of a flowchart for a calibration process in the preferred embodiment for a single microphone. The calibration process may be applied to each microphone individually, or may be applied to groups of microphones. A compute maximum loudness on calibration region block <NUM> produces calibration loudness <NUM> from the sound values <NUM> that represent the sound values from region A of <FIG> of the microphone. The size of region A of <FIG> may contain a limited samples to perform an effective calibration so the multiple sound profiles can be concatenated together before being fed into the calibration process. Block <NUM> determines if the calibration loudness <NUM> is within an acceptable tolerance range. The acceptable range is typically ±<NUM> ADC steps from the default calibration value stored in system memory <NUM>, or a certain percentage of the full scale of the ADC. Note that each microphone 200a, 200b and 200c can have a different default calibration value stored in system memory <NUM>. If the calibration loudness is within an acceptable range then processing continues to block <NUM> where no calibration is needed. If the calibration loudness <NUM> is not with the acceptable range then processing continues to block <NUM> which determines if the calibration loudness <NUM> is greater than the default calibration value TC stored in system memory <NUM>. If the calibration loudness <NUM> is not greater than the default calibration value TC then the microphone is picking up less sound than previously used in the sound jam processing. To compensate for the reduction in the calibration loudness <NUM>, the threshold values used by the sound jam detection processing for that microphone are decreased in block <NUM> to the increase the sensitivity of sound jam detector <NUM>. If the calibration loudness is greater than the default calibration value then the medium transport system <NUM> is getting louder. This could be the result of a mechanical part becoming worn and is in need of replacement or there is a change in the sensitivity of the microphone. The operator is notified in block <NUM> and has the option to accept the change in calibration loudness <NUM> in block <NUM>. If the operator does not accept the change in calibration loudness <NUM> then the medium transport system <NUM> requires servicing as shown in block <NUM>. If the operator accepts the increase in calibration loudness <NUM> then the microphone is picking up more sound than previous. To compensate for the increase in the calibration loudness <NUM>, the threshold values used by the sound jam detection processing for that microphone are increased in block <NUM> to the decrease the sensitivity of sound jam detector <NUM>.

The initial thresholds TA1, TB1, TC1, TA21, TB21, TA22, TC22, TB23, TC23, TA3, TB3 and TC3 may be computed through a training process. The sound profiles <NUM>, <NUM> and <NUM> of the sound values from microphones 200a, 200b and 200c are captured from the normal passage of hardcopy media <NUM> through the media transport path <NUM> to create a library of sound profiles. The library consists of a collection of sound profiles <NUM>, <NUM> and <NUM> for N<NUM> hardcopy media <NUM> where N<NUM> is typically <NUM>. The training process then analyzes the sound profile <NUM>, <NUM> and <NUM> for each hardcopy media <NUM> in the library and computes the maximum sound value for microphones 200a, 200b and 200c over the library of sound profiles. To find the thresholds used for multiple threshold tests <NUM> - <NUM>, the sound profiles for the microphones are compared to each other to find the sound values that produce the maximum loudness for the microphones together. The process is repeated while all but one of the microphone's sound value is held constant. While holding one microphone's sound value constant, the other microphone(s) sound profiles are searched for sound values that produce a loudness that is greater than the previous loudness found. If a greater loudness is found then that sound value for the microphone replaces the current loudness for that microphone. The process continues searching the sound profiles of each microphone while holding the other microphone sound value constant.

These maximum sound values are then used to set the thresholds TA1, TB1, TC1, TA21, TB21, TA22, TC22, TB23, TC23, TA3, TB3 and TC3. Since a library of sound profiles was created using the normal passage of hardcopy media <NUM> through the media transport path <NUM>, a jam <NUM> would be indicted anytime the sound value A <NUM>, B <NUM> and C <NUM> produced a loudness A <NUM>, loudness B <NUM> or loudness C <NUM> which exceeded the threshold tests as described in <FIG>.

The operator may put the medium transport system <NUM> into a training mode to allow for optimization of thresholds to match the type of hardcopy media <NUM> being loaded into the input tray <NUM>. The thresholds TA1, TB1, TC1, TA21, TB21, TA22, TC22, TB23, TC23, TA3, TB3 and TC3 can be generic thresholds meaning that the thresholds will work for wide range of types of hardcopy media <NUM>. They may also be custom thresholds meaning that thresholds TA1,TB1, TC1, TA21, TB21, TA22, TC22, TB23, TC23, TA3, TB3 and TC3 are defined for a specific type of hardcopy media <NUM>. For example, a medium transport system <NUM> may be processing only <NUM># NCR media. In this case the training would be done using only <NUM># NCR media in order to optimize the thresholds for this type of media. Whenever a media transport system restricts its use to a particular set of types of media, the training may be done using only those media types to optimize the thresholds. Alternatively each microphone's thresholds may be set as a mixture of generic and custom thresholds across the entire sound profile thereby allowing the sound detection process <NUM> to use custom thresholds specific to a type hardcopy media in specific regions of the sound profile <NUM>, <NUM> and <NUM>.

Claim 1:
A system for indicating a medium jam along a medium transport path comprising:
(a) one or more rollers for use in conveying a medium along the medium transport path;
(b) at least one microphone for detecting the sound of the medium being transported and producing a signal representing the sound;
(c) a processor configured to produce sound values from the sound signal and further configured to:
(i) compute pre-transport path maximum values responsive to the sound values from the at least one microphone from a region before the medium transport path;
(ii) compute transport path maximum values responsive to the sound values from the at least one microphone from a region within the medium transport path;
(iii) compute post transport path maximum values responsive to the sound values from the at least one microphone from a region after the medium transport path;
(iv) indicate a location of the medium jam responsive to the maximum values; and
(v) produce a calibration loudness value from sound values associated with the medium transport path at a time before an urging roller has urged the medium into the medium transport path;
(vi) compare the calibration loudness value to an acceptable tolerance range to determine when calibration is needed;
(vii) compare the calibrate loudness value to a default calibration value and increase a jam detection sensitivity when the calibration loudness value is not greater than the default calibration value; and
(viii) produce an audible or visual alert to an operator that maintenance or replacement of parts is required when the calibration loudness value is greater than the default calibration loudness and decrease jam sensitivity when the operator indicates that the calibration loudness value is acceptable.