Appliance and method of determining abnormality

Abstract

To improve the accuracy of determining an original not to be carried normally.SOLUTION: An appliance comprises a transport unit that carries an original to be read as an image, a sound collecting unit that gathers sound occurring in a period of time the original is being carried, and a determining unit that determines a presence / absence of abnormality in transporting the original by chronologically comparing first time-series data of the sound with a threshold set chronologically for the period of time. The threshold is derived so as to include, in a range equal to or smaller than the threshold, a region higher in occurrence frequency more than a region lower in occurrence frequency in second time-series data of the sound in the period of time on a plurality of originals to be carried normally.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an apparatus and an abnormality determination method. [Background technology]

[0002] There are cases where an original that cannot be conveyed normally, such as a stapled original, is set in an automatic document feeder (ADF) used in a copying machine, etc. In such a case, there is known an automatic document feeder (ADF) that has a function to determine that the original cannot be conveyed normally based on the sound of the original document feeder operating and to stop conveyance, thereby preventing damage to the original document (wrinkles, tears) that may occur due to conveyance abnormalities (for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0003] However, conventional document feeders have had the problem that even when a document that can be fed normally is set, the collision sound generated when separating multiple sheets of document may result in the device mistakenly determining that the document cannot be fed normally.

[0004] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to improve the accuracy of determining whether a document cannot be normally conveyed. [Means for solving the problem]

[0005] In order to solve the above problem, the device has a transport unit that transports a document whose image is to be read, a sound collection unit that collects sound generated during the period in which the document is transported, and a judgment unit that judges whether or not there is an abnormality in the transport of the document by comparing first time series data regarding the sound with a threshold value set in time series for the period, the threshold value being derived so that areas with a high occurrence frequency in second time series data regarding the sound during the period for multiple documents that can be transported normally are more likely to be below the threshold value than areas with a low occurrence frequency. [Effects of the Invention]

[0006] This improves the accuracy of determining whether a document cannot be conveyed normally. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an example of a schematic configuration of a copying machine 100 according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing a scanner 150 and an ADF 51 of the copying machine 100. [Figure 3] FIG. 1 is an enlarged view showing the main components of the ADF 51 together with the upper part of the scanner 150. [Figure 4] FIG. 2 is a diagram showing the appearance of the ADF 51. [Figure 5] 2 is a diagram showing an example of the configuration of a part of an electric circuit of the copying machine 100 according to the first embodiment. FIG. [Figure 6] 10 is a flowchart illustrating an example of a processing procedure executed by the copying machine 100 according to the first embodiment. [Figure 7] FIG. 2 is a diagram illustrating an example of sound data. [Figure 8] FIG. 10 is a diagram illustrating an example of a threshold function F(t). [Figure 9] FIG. 10 is a diagram illustrating an example of a change in the value of a counter variable C. [Figure 10] 10 is a flowchart illustrating an example of a processing procedure for deriving a threshold function F(t) according to the first embodiment. [Figure 11] FIG. 2 is a diagram showing an example of a probability density distribution of sound intensity levels at time T. [Figure 12] FIG. 10 is a diagram for explaining the derivation of an approximate curve showing the relationship between time and sound intensity. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, an electrophotographic copying machine (hereinafter referred to as "copying machine 100") will be described as an example of a device. However, this embodiment can be applied to any device that has a transport unit for reading an image from a document, such as a scanner, a facsimile, or a multifunction device.

[0009] First, the basic configuration of copier 100 will be described. Fig. 1 is a diagram showing an example of the schematic configuration of copier 100 in the first embodiment. In Fig. 1, copier 100 includes image forming section 1 as an image forming device, sheet supply device 40, and image reading system 50. Image reading system 50 includes scanner 150 as an image reading device fixed on image forming section 1, and automatic document feeder (hereinafter referred to as "ADF") 51 supported by scanner 150.

[0010] The sheet supply device 40 has one or more paper feed cassettes, and conveys recording sheets set in the paper feed cassettes to the image forming unit 1.

[0011] The image forming unit 1 forms a toner image of black, yellow, magenta, and cyan (K, Y, M, C) from the image read from the original MS by the scanner 150, and fixes the toner image on a recording sheet transported from the sheet supply device 40.

[0012] Scanner 150, which is fixed on image forming unit 1, has a movable reading unit 152. Scanner 150 and ADF 51 each have a fixed reading unit. Mobile reading unit 152 is disposed directly below a second contact glass (not shown) fixed to the upper wall of the casing of scanner 150 so as to come into contact with document MS, and can move an optical system consisting of a light source, a reflecting mirror, etc., left and right in the figure. As the optical system moves from left to right in the figure, light emitted from the light source is reflected by a document (not shown) placed on the second contact glass, and then passes through multiple reflecting mirrors before being received by image reading sensor 153 fixed to the scanner body.

[0013] Meanwhile, the fixed reading unit is comprised of a first-side fixed reading unit 151 disposed inside the scanner 150 and a second-side fixed reading unit (not shown) disposed inside the ADF 51. The first-side fixed reading unit 151, which includes a light source, a reflecting mirror, an image reading sensor such as a CCD, and the like, is disposed directly below a first contact glass (not shown) fixed to the upper wall of the casing of the scanner 150 so as to come into contact with the original MS. When a sheet-like original MS transported by the ADF 51 (described later) passes over the first contact glass, light emitted from the light source is sequentially reflected by the original surface, passes through multiple reflecting mirrors, and is received by the image reading sensor. This allows the first side of the original MS to be scanned without moving the optical system consisting of the light source, reflecting mirrors, and the like. The second-side fixed reading unit scans the second side of the original MS after it has passed the first-side fixed reading unit 151.

[0014] The ADF 51, which is disposed on the scanner 150, includes a main body cover 52 and a document placement table 53, which serves as a document placement means for placing documents MS before scanning. The ADF 51 also includes a transport unit 54 for transporting the documents MS as sheet materials, and a document stack table 55 for stacking the scanned documents MS. As shown in FIG. 2, the ADF 51 is supported by a hinge 159 fixed to the scanner 150 so as to be able to swing up and down. The ADF 51 swings up and down like a door, exposing a first contact glass 154 and a second contact glass 155 on the top surface of the scanner 150 when open. In the case of single-sided bound documents, such as a book bound at one corner of a stack, the documents cannot be separated one by one, and therefore cannot be transported by the ADF. Therefore, in the case of single-sided bound documents, the ADF 51 is opened as shown in FIG. 2, and the single-sided bound document to be scanned is placed face down on the second contact glass 155, and the ADF is then closed. Then, the image of the page is read by the moving reading unit 152 of the scanner 150 shown in FIG.

[0015] On the other hand, in the case of a stack of multiple independent documents MS, the documents MS can be automatically transported one by one by the ADF 51, and the first-side fixed reading unit 151 in the scanner 150 and the second-side fixed reading unit in the ADF 51 can sequentially read the documents. In this case, the user places the document stack on the document placing table 53 and then presses a copy start button (not shown). The ADF 51 then feeds the documents MS of the document stack placed on the document placing table 53 into the transport unit 54 in order from top to bottom, and transports them toward the document stack table 55 while inverting them. During this transport process, the documents MS are passed directly above the first-side fixed reading unit 151 of the scanner 150 immediately after being inverted. At this time, the image of the first side of the documents MS is read by the first-side fixed reading unit 151 of the scanner 150.

[0016] Fig. 3 is an enlarged configuration diagram showing the main configuration of the ADF 51 together with the upper part of the scanner 150. Fig. 4 is a diagram showing the external appearance of the ADF 51. The ADF 51 is equipped with a document setting section A, a separation feeding section B, a registration section C, a turning section D, a first reading conveyance section E, a second reading conveyance section F, a paper discharge section G, a stacking section H, etc. The ADF 51 also has a document conveyance path for conveying the document MS from the document placing table 53 toward the first-side fixed reading section 151, which is the image reading position.

[0017] The document setting unit A has a document placement table 53 on which a stack of documents MS is set. The separation and feeding unit B separates and feeds documents MS one by one from the set stack of documents MS. The registration unit C temporarily bumps against the fed documents MS, aligns them, and then sends them out. The turning unit D has a curved conveying section that curves in a C shape, and turns the documents MS upside down while folding them back within this curved conveying section. The first reading and conveying unit E conveys the documents MS on the first contact glass 154, and causes the first side of the documents MS to be read by the first-side fixed reading unit 151 disposed inside the scanner 150 below the first contact glass 154. The second reading and conveying unit F conveys the documents MS below the second-side fixed reading unit 95, and causes the second side of the documents MS to be read by the second-side fixed reading unit 95. The paper discharge section G discharges the document MS, the images of both sides of which have been read, toward the stack section H. The stack section H stacks the document MS on a document stack table 55.

[0018] The original MS is set with its leading edge placed on the movable original table 56, which can swing in the directions of arrows a and b in the figure depending on the thickness of the stack of originals MS, and its trailing edge placed on the original placement table 53. At this time, the side guides on the original placement table 53 are abutted against both ends of the original in the width direction (the direction perpendicular to the plane of the figure), thereby adjusting the position in the width direction. The original MS set in this manner pushes up a lever member 62, which is swingably disposed above the movable original table 56. Accordingly, the original set sensor 63 detects the setting of the original MS and transmits a detection signal to the controller of the ADF 51 (controller 904, described below). This detection signal is then sent from the controller of the ADF 51 (controller 904, described below) to the reading control unit of the scanner via the I / F.

[0019] A first length sensor 57 and a second length sensor 58, each consisting of a reflective photosensor or an actuator-type sensor, are held on the document placement table 53. These length sensors detect the length of the document MS in the transport direction.

[0020] Above the stack of originals MS placed on movable original table 56, there is disposed a pickup roller 80 that is supported by a cam mechanism so as to be movable in the vertical direction (the directions of arrows c and d in the figure). This cam mechanism is driven by a pickup motor to move pickup roller 80 up and down. When pickup roller 80 moves upward, movable original table 56 also swings in the direction of arrow a in the figure, and pickup roller 80 comes into contact with the uppermost original MS in the stack of originals MS. As movable original table 56 continues to rise, table rise detection sensor 59 eventually detects that movable original table 56 has reached its upper limit. This stops the pickup motor and stops the upward movement of movable original table 56.

[0021] The operator operates a main body operation unit, which is comprised of a numeric keypad, a display, etc., provided on the main body of copier 100, to set the reading mode, indicating whether it is a double-sided reading mode or a single-sided reading mode, and to press a copy start key. When the copy start key is pressed, a document feed signal is sent from a main body control unit (not shown) to a controller of ADF 51. Then, pickup roller 80 is rotated by the forward rotation of a paper feed motor (paper feed motor 191, described later), and the document MS on movable document table 56 is fed out from movable document table 56.

[0022] When setting the double-sided reading mode or single-sided reading mode, it is possible to collectively set double-sided or single-sided reading for all of the originals MS placed on the movable original table 56. It is also possible to set the reading mode individually for each individual original MS, for example, by setting the first and tenth originals MS to double-sided reading mode while setting the other originals MS to single-sided reading mode.

[0023] The document MS delivered by the pickup roller 80 enters the separation and transport section B and is delivered to a contact position with the paper feed belt 84. The paper feed belt 84 is tensioned by a drive roller 82 and other components, and is moved endlessly in the clockwise direction in the figure by the rotation of the drive roller 82 as the paper feed motor rotates forward. A separation roller 85, which is driven to rotate clockwise in the figure by the forward rotation of the paper feed motor, contacts the lower tension surface of the paper feed belt 84. At the contact point, the surface of the paper feed belt 84 moves in the paper feed direction. In contrast, the separation roller 85 contacts the paper feed belt 84 with a predetermined pressure, and when the separation roller 85 is in direct contact with the paper feed belt 84 or when only one document MS is sandwiched in the contact area, the separation roller 85 rotates along with the belt or the document MS. However, when multiple documents MS are sandwiched in the contact area, the accompanying rotation force becomes lower than the torque of the torque limiter, and the separation roller 85 rotates clockwise in the figure, which is opposite to the accompanying rotation direction. As a result, the separation roller 85 applies a moving force in the opposite direction to the paper feeding to the documents MS below the top, and only the top document MS is separated from the several documents (hereinafter, the operation up to this point is referred to as the paper feeding / separation operation).

[0024] The document MS, separated into a single sheet by the action of a separating section such as the paper feed belt 84 and separation roller 85, enters the registration section C. Then, as the document passes directly below the abutment sensor 72, its leading edge is detected. At this time, the pickup roller 80, which receives the driving force of the pickup motor, is still rotating, but as the movable document table 56 descends, it is separated from the document MS, and the document MS is transported only by the endless moving force of the paper feed belt 84. Then, the endless movement of the paper feed belt 84 continues for a predetermined time from the timing when the leading edge of the document MS is detected by the abutment sensor 72. As a result, the leading edge of the document MS abuts against the contact portion between the pull-out drive roller 86 and the pull-out driven roller 87, which is driven to rotate while abutting against the pull-out drive roller 86.

[0025] The pull-out driven roller 87 serves to transport the document MS to the pair of intermediate rollers 66 downstream in the document transport direction, and is driven to rotate by the reverse rotation of the paper feed motor. When the paper feed motor reverses, the pull-out driven roller 87 and one of the rollers of the pair of intermediate rollers 66 that are in contact with each other start to rotate, and the endless movement of the paper feed belt 84 stops. At this time, the rotation of the pickup roller 80 also stops.

[0026] The document MS sent out from the pull-out driven roller 87 passes directly below the document width sensor 73. The document width sensor 73 has multiple paper detection units, each consisting of a reflective photosensor or the like, which are aligned in the document width direction (the direction perpendicular to the plane of the drawing). The widthwise size of the document MS is detected based on which paper detection unit detects the document MS. The length of the document MS in the transport direction is detected based on the timing from when the leading edge of the document MS is detected by the abutment sensor 72 to when the trailing edge of the document MS is no longer detected by the abutment sensor 72.

[0027] The leading edge of the document MS, whose widthwise size has been detected by the document width sensor 73, enters the turning section D and is sandwiched in the contact area between the rollers of the intermediate roller pair 66. The transport speed of the document MS by this intermediate roller pair 66 is set to be faster than the transport speed of the document MS in the first reading and transporting section E, which will be described later. This shortens the time it takes to send the document MS to the first reading and transporting section E.

[0028] The leading edge of the document MS being transported within the turning section D passes a position facing the reading entrance sensor 67. When the leading edge of the document MS is detected by the reading entrance sensor 67, the document transport speed by the intermediate roller pair 66 is reduced until the leading edge reaches the position of the reading entrance roller pair (pair of 89 and 90) on the downstream side in the transport direction. In addition, as the reading motor (not shown) starts to rotate, one roller of the reading entrance roller pair (89, 90), one roller of the reading exit roller pair 92, and one roller of the second reading exit roller pair 93 each start to rotate.

[0029] Within the turning section D, the document MS is reversed upside down and its conveying direction is reversed while it is conveyed along the curved conveying path between the pair of intermediate rollers 66 and the pair of reading entrance rollers (89, 90). Then, the leading edge of the document MS that has passed through the nip between the pair of reading entrance rollers (89, 90) passes directly below the registration sensor 65. Hereinafter, the operation up to this point after the paper feeding / separation operation is referred to as the pull-out operation.

[0030] When the leading edge of the document MS is detected by the registration sensor 65, the document transport speed is decelerated over a predetermined transport distance. Then, the transport motor (transport motor 192, described below) is stopped to stop the rotational drive of the pull-out drive roller 86 and the pair of intermediate rollers 66, and the reading motor (not shown) is stopped to stop the rotational drive of the pair of reading entrance rollers. As a result, the transport of the document MS is temporarily stopped at the registration position in front of the first reading transport unit E. In addition, a registration stop signal is sent to the reading control unit (not shown).

[0031] In this embodiment, a sound collection microphone 201 is further disposed at a position as shown in FIGS. 3 and 4. Specifically, the sound collection microphone 201 is disposed inside the paper feed cover 98, upstream of the separation mechanism constituted by the paper feed belt 84 and separation roller 85. This is because, when originals MS are bound with clips or staples, the topmost original MS attempts to be fed in the paper feed direction by the paper feed belt 84, but because it is fixed to the underlying originals MS by the binding, distortion occurs in the topmost original MS, and wrinkles or folds occur upstream of the paper feed belt 84. The sound collection microphone 201 is intended to be disposed near the position where these wrinkles or folds occur. The sound collection microphone 201 is disposed approximately in the center in the width direction (the direction perpendicular to the plane of the drawing). This is intended to place the sound collection microphone 201 at an average position where wrinkles or folds occur for originals MS of various widths.

[0032] 5 is a diagram showing an example of the configuration of part of the electrical circuit of the copier 100 in the first embodiment. A main body control unit 901 that controls the image forming unit 1, a reading control unit 903 that controls the scanner 150, and a controller 904 that controls the ADF 51 are each composed of a CPU, RAM, ROM, etc. The main body control unit 901 and the reading control unit 903, the reading control unit 903 and the controller 904, and the controller 904 and the main body control unit 901 are each connected to each other and are capable of communicating with each other.

[0033] A transport motor 192 connected to the controller 904 is a rotational drive source for the pull-out drive roller 86 and the pair of paper discharge rollers 94 in the ADF 51. A pull-out clutch 193 connected to the controller 904 connects or disconnects the rotational drive force of the transport motor 192 to or from the pull-out drive roller 86. A paper discharge clutch 194 connects or disconnects the rotational drive force of the transport motor 192 to or from the pair of paper discharge rollers 94, which are the feed-out transport means.

[0034] Upon receiving the registration stop signal from the controller 904, the reading control unit 903 transmits a reading start signal, which is a paper feed permission signal, to the controller 904. The controller 904 then resumes rotation of the transport motor 192 and the reading motor. Then, at the timing when the leading edge of the original MS, calculated based on the pulse count of the reading motor, reaches the reading position by the first-side fixed reading unit 151, the controller 904 transmits a gate signal indicating the sub-scanning direction effective image area of ​​the first side of the original MS to the reading control unit 903. This transmission continues until the trailing edge of the original MS leaves the reading position by the first-side fixed reading unit 151, and the first side of the original MS is read by the first-side fixed reading unit 151.

[0035] After passing through the first reading conveyance unit E, the document MS passes through the reading exit roller pair 92, and then its leading edge is detected by the paper discharge sensor 61. When the single-sided reading mode is set, there is no need to read the second side of the document MS by the second-side fixed reading unit 95. Therefore, when the leading edge of the document MS is detected by the paper discharge sensor 61, the driving force of the conveyance motor is connected to the paper discharge roller pair 94 by the paper discharge clutch 194. Then, based on the paper discharge motor pulse count after the leading edge of the document MS is detected by the paper discharge sensor 61, the timing at which the trailing edge of the document MS will leave the nip of the paper discharge roller pair 94 is calculated. Then, based on the result of this calculation, the operation of the paper discharge clutch 194 is stopped.

[0036] On the other hand, when the double-sided reading mode is set, the timing from when the leading edge of the original MS is detected by the paper discharge sensor 61 until the original reaches the second-side fixed reading unit 95 is calculated based on the pulse count of the reading motor. Then, at that timing, the controller transmits a gate signal indicating the effective image area in the sub-scanning direction on the second side of the original MS to the reading control unit. This transmission continues until the trailing edge of the original MS leaves the reading position of the second-side fixed reading unit 95, and the second side of the original MS is read by the second-side fixed reading unit 95.

[0037] The second-side fixed reading unit 95 is composed of a contact image sensor (CIS), and its reading surface is coated to prevent vertical reading streaks caused by glue-like foreign matter adhering to the document MS adhering to the reading surface. A second reading roller 96 is disposed opposite the second-side fixed reading unit 95 as a document support means for supporting the document MS from the non-reading side. This second reading roller 96 prevents the document MS from floating at the reading position by the second-side fixed reading unit 95, and also functions as a reference white area for acquiring shading data in the second-side fixed reading unit 95.

[0038] The sound collecting microphone 201 is also connected to the controller 904. The sound information collected by the sound collecting microphone is converted into PCM data by an AD converter in the controller 904 and stored in RAM.

[0039] The following describes the processing procedure executed by the copying machine 100. Fig. 6 is a flowchart for explaining an example of the processing procedure executed by the copying machine 100 in the first embodiment.

[0040] When the copier 100 separates and feeds each document MS one by one from a stack of documents MS whose images are to be read and which are set on the document placing tray 53, the copier 100 performs processing for each document MS according to the processing procedure shown in FIG. 6. Note that in order to increase the reading throughput, the copier 100 continuously feeds the documents MS while leaving sufficient space between each document MS so that the documents do not overlap, and thus multiple documents MS are simultaneously present on the document transport path with a gap between them. Therefore, the processing procedure shown in FIG. 6 is executed in parallel for each document MS, leaving a gap between each document MS. The processing procedure shown in FIG. 6 is executed by the CPU of the controller 904 of the ADF 51 based on a program written in the ROM of the controller 904.

[0041] When the copy start key is pressed, a document feed signal is sent from the main body control unit 901 to the controller 904 of the ADF 51. The controller 904 then starts the aforementioned "document feed / separation operation." Specifically, the pickup roller 80 is rotated in the forward direction by the forward rotation of the document feed motor 191, and the document MS on the movable document table 56 is sent out from the movable document table 56 (S101).

[0042] Next, the controller 904 initializes a counter variable C to 0 (S102). As will be apparent from the following description, the counter variable C is a variable used to generate a feature amount of the transport sound of the original MS (the operation sound of the paper feeding / separation operation).

[0043] Next, the controller 904 captures the transport sound (sound signal) generated by the transport of the document MS, which is collected by the sound collection microphone 201, and records it in the RAM in the controller 904 (S103). This sound collection operation (collection and recording of the transport sound) continues to be executed simultaneously with steps S104 to S108 until a transport abnormality is determined in step S107 or YES is determined in step S108.

[0044] When step S103 is first executed, the leading edge of the document MS is near the pickup roller 80 (Figure 3), and the trailing edge of the document MS is on the document placing tray 53 or the movable document table 56 (the position of the trailing edge depends on the paper length of the document MS).

[0045] When a sound signal for a certain period of time (this time interval is referred to as Ts) has accumulated (recorded) in RAM, the controller 904 calculates a time series of sound intensity levels (first time series data related to sound) for the sound signal (sound signal for the certain period of time Ts) (S104). Specifically, the controller 904 applies a short-time Fourier transform (STFT) to the sound signal to obtain a power spectrum of the sound signal. To avoid the driving noise of the paper feed motor 191 (mainly 10 kHz or less), the controller 904 applies a high-pass filter to the obtained power spectrum to remove sound components below 10 kHz, and then calculates the average value of sound intensity for all frequencies by averaging the power spectrum from which the sound components have been removed on the frequency axis, and then performs decibel conversion to obtain the sound intensity level.

[0046] Note that step S104 is repeatedly executed at each time Ts, thereby obtaining a time series of sound intensity levels (hereinafter referred to as "sound data").

[0047] Fig. 7 is a diagram showing an example of sound data. Fig. 7 shows two examples of sound data (a) and (b) (i.e., when two sheets of original MS are transported, respectively). (a) shows an example of sound data when the original MS can be transported normally, and (b) is an example of sound data when the original MS is erroneously stapled (causing a transport abnormality, resulting in a paper jam or damage to the original). Execution of step S104 obtains one sound intensity level, so for example, if the current time is T, the sound intensity corresponding to T in Fig. 7 will be obtained.

[0048] Next, the controller 904 compares the level with a threshold value corresponding to the current time among threshold values ​​that change in a time series (according to time) defined by a predefined threshold function F(t) (S105). Here, the current time refers to the time that has elapsed since the start of the paper feed / separation operation (i.e., the start of feeding the original MS) (since the start of S101).

[0049] FIG. 8 is a diagram showing an example of the threshold function F(t). FIG. 8 shows a coordinate system in which the x-axis represents time (the elapsed time from the start of feeding the original MS) and the y-axis represents the sound intensity level. The function shown by the dashed curve in this coordinate system is the threshold function F(t). In other words, the threshold function F(t) is a function that shows the correspondence between time and the threshold for the sound intensity level. During paper feeding / separation operations, even during normal operation, the intensity level of the generated sound can change over time. Therefore, in this embodiment, the threshold for the sound intensity level is not kept constant but is changed over time. The method of deriving the threshold function F(t) (learning method) will be described later.

[0050] In step S105, the controller 904 applies the current time to the threshold function F(t) to identify a threshold corresponding to the current time, and compares the threshold with the sound intensity level at the current time.

[0051] If the sound intensity level at the current time exceeds the threshold value (YES in S105), the controller 904 adds 1 to the counter variable C (S106). That is, the value of the counter variable C indicates the number of times that the sound intensity level at time T exceeds the threshold value set in chronological order. The value of the counter variable C becomes a feature quantity for detecting abnormalities in the transport of the original MS.

[0052] Next, the controller 904 compares the value of the counter variable C with a threshold value Cth to determine whether or not there is an abnormality in the transport of the original MS (S107). If the value of C is less than the threshold value Cth (NO in S107), the controller 904 determines that the transport is normal, and repeats step S103 and subsequent steps until a certain time has elapsed since the start of the paper feed / separation operation (S108). This certain time may be set based on the time it is expected that the leading edge of the original MS will reach the vicinity of the pull-out drive roller 86. If C≧Cth (YES in S107), the controller 904 determines that there is an abnormality in the transport, stops the transport operation, and ends the reading operation (S109).

[0053] For example, when the sound data is as shown in FIG. 7 and the threshold function F(t) is as shown in FIG. 8, the value (feature amount) of the counter variable C changes as follows according to the repetition of step S103 and subsequent steps over a certain period of time.

[0054] Fig. 9 is a diagram showing an example of changes in the value of the counter variable C. In the upper part of Fig. 9, the threshold function F(t) shown in Fig. 8 is superimposed on the coordinate systems showing the sound data of (a) and (b) shown in Fig. 7. In the lower part of Fig. 9, changes in the value of the counter variable C based on the sound data of (a) and (b) are shown.

[0055] When the original MS can be conveyed normally as in (a), the value of the counter variable C rises to a certain extent but does not reach the threshold value Cth. On the other hand, when the original MS is a stapled original as in (b), after the original MS enters the separation section (paper feed belt 84, separation roller 85, etc.), the ADF 51 attempts to separate the topmost sheet. However, because the topmost sheet is stapled to the sheets below it, a force acts in a direction that hinders its progress, causing the original to bend or skew. As a result, the sound intensity level becomes higher than during normal conveyance, and the value of the counter variable C rises. As a result, the value of the counter variable C exceeds the threshold value Cth within a certain period of time. Therefore, in the case of (b), a conveyance abnormality is determined.

[0056] If a certain period of time has elapsed without determining that a transport abnormality has occurred (YES in S108), the controller 904 performs control in accordance with the normal reading operation of the ADF 51. Specifically, the controller 904 causes the ADF 51 to perform a pull-out operation (S110), and temporarily stops the transport of the original MS at a registration position in front of the first reading and transport unit E (S111). Next, the controller 904 waits for a reading start signal from the reading control unit 903 (S112). When the controller 904 receives the reading start signal (YES in S112), the reading control unit 903 executes the reading process (S113).

[0057] Next, a method for deriving (learning) the threshold function F(t) will be described.

[0058] During the development stage of the ADF51, various documents that can be normally transported are used to collect a large amount of sound data (second time-series data related to sound) as shown in Figure B9 during the period when the documents are transported (hereinafter referred to as the "transport period"). The length of each sound data is the fixed time length described in step S108. In the sound data acquired in this manner, a separation section collision sound occurs when the leading edge of the document enters the separation section, and the sound intensity level tends to increase. However, the magnitude, occurrence timing, and duration of the separation section collision sound vary depending on conditions such as the paper type, basis weight, size, and friction coefficient of the document. Therefore, it is recommended to collect various sound data using documents under various conditions. The threshold function F(t) is derived (learned) using the collected sound data (hereinafter referred to as the "collected data") as learning data.

[0059] Fig. 10 is a flowchart for explaining an example of the processing procedure for deriving the threshold function F(t) in the first embodiment. In the following, an example will be described in which the controller 904 executes the processing procedure in Fig. 10, but another computer may also execute the processing procedure in Fig. 10.

[0060] In step S201, the controller 904 sets the time T to zero.

[0061] Next, the controller 904 calculates the sound intensity levels in the divided periods corresponding to time T to T+Ts, among the divided periods obtained by dividing the transportation period corresponding to each collected data into Ts, and calculates the probability density distribution of the sound intensity levels at time T (the probability density distribution of the sound intensity levels corresponding to the divided period) based on the set of obtained sound intensity levels (S201).

[0062] Fig. 11 is a diagram showing an example of a probability density distribution of sound intensity levels at time T. In the coordinate system of Fig. 11, the x-axis corresponds to sound intensity levels, and the y-axis corresponds to probability density. A curve mapped onto the coordinate system indicates the probability density distribution. In other words, the probability density distribution is a probability density distribution (probability density function) in which sound intensity levels are random variables.

[0063] Next, the controller 904 determines the sound intensity level at which the top percentage (top percentile) in the determined probability density distribution is a predetermined value (e.g., 1%) (S203). That is, a sound intensity level L is determined so that the area P becomes a predetermined value in Fig. 11. The sound intensity level L can be said to be a sound intensity level that is more likely to be found below L in areas with a high occurrence frequency than in areas with a low occurrence frequency in the collected data.

[0064] Next, the controller 904 advances the time T by Ts (S204).

[0065] Next, the controller 904 determines whether the time T exceeds the length (time length) of the collected data (S205). If the time T is equal to or less than the length of the collected data (NO in S205), steps S202 and after are repeated.

[0066] When the time T exceeds the length of the collected data (YES in S205), the controller 904 obtains an approximate curve showing the relationship between time and sound intensity based on the sequence of points of sound intensity L obtained for each time (S206).

[0067] FIG. 12 is a diagram for explaining the derivation of an approximation curve showing the relationship between time and sound intensity. FIG. 12 shows a coordinate system with time on the x-axis and sound intensity level on the y-axis. In this coordinate system, each black dot represents the sound intensity level L obtained at that time. This point indicates that only a certain percentage of data at that time had a sound intensity level higher than that value. Controller 904 calculates an approximation curve for this sequence of points using methods such as the least squares method or polynomial approximation.

[0068] Next, the controller 904 offsets the approximation curve by a fixed value in the positive direction of the y-axis (sound intensity level) to provide a margin for erroneous detection (S207).

[0069] The approximate curve obtained in this way becomes the threshold function F(t) that has as small a value as possible while avoiding collision noise in the separation section for various documents that can be normally conveyed. However, step S207 may not be executed, and the approximate curve obtained in step S206 may be used as the threshold function F(t). The threshold function F(t) is calculated, for example, during the development stage of the ADF 51 and stored in the ROM of the controller 904.

[0070] As described above, according to the first embodiment, a time-series threshold (threshold function F(t)) is set for the elapsed time from the start of paper feeding, and the threshold is compared with time-series data on the sound generated by the transport to make a judgment regarding the transport of the document. As a result, the threshold can be changed between a time range where the probability of the collision sound occurring during separation is high and a time range where the probability of the collision sound occurring during separation is low, thereby reducing the possibility of erroneous judgment due to the collision sound during separation. Therefore, the accuracy of judgment regarding documents that cannot be transported normally can be improved.

[0071] Furthermore, because the timing of occurrence of the collision sound during separation varies depending on factors such as the degree of slippage of the document, simply masking the time range in which the collision sound is likely to occur requires masking a wide time range, which has a negative impact on detection. In this embodiment, the probability density distribution of the sound intensity at each time point is calculated from the transport sound data (collected data) of a large number of normal documents, and points of sound intensity where the occurrence probability at a certain point is less than a certain value are found. Based on this sequence of points, parameters that determine the shape of the threshold function F(t) are determined, thereby achieving a balance between reducing false detections and improving detection accuracy.

[0072] Furthermore, in this embodiment, the sound intensity level is treated as sound data (time-series data related to sound) and a single decibel value is used, thereby enabling highly accurate judgments to be made over a wide range of values ​​with a simple configuration that does not consume much CPU resources.

[0073] Furthermore, by deriving the threshold function F(t) based on the probability density distribution of sound intensity levels of multiple collected data, it is possible to determine the threshold required for judgment in a simple manner from real data.

[0074] Furthermore, by determining whether or not there is an abnormality based on the number of times the sound intensity level exceeds the threshold, the influence of outliers such as noise exceeding the threshold can be mitigated, increasing the likelihood of correctly determining whether or not there is an abnormality.

[0075] Next, a second embodiment will be described. In the second embodiment, differences from the first embodiment will be described. Therefore, unless otherwise specified, the second embodiment may be the same as the first embodiment.

[0076] When the conveying speed during the paper feeding / separating operation is fast, the sound intensity level becomes high, and when the conveying speed is slow, the sound intensity level becomes low. Therefore, the threshold function F(t) depends on the conveying speed.

[0077] Therefore, in the second embodiment, in order to derive the threshold function F(t), a group of voice data collected for each conveying speed is generated. The controller 904 generates the threshold function F(t) for each conveying speed by executing the processing procedure in FIG. 10 based on the group of voice data related to the conveying speed, and records the generated threshold function F(t) in the ROM of the controller 904. Therefore, the threshold function F(t) is recorded in the ROM for each conveying speed. Note that each conveying speed may be for each speed within a certain range.

[0078] When the ADF 51 actually operates, the main body control unit 901 instructs the ADF 51 to select a transport speed based on the copy, scan, or paper thickness mode specified by the user. The controller 904 performs transport operations, including paper feeding and separation, based on the instructed transport speed. At this time, the controller 904 executes the processing procedure shown in FIG. 6 using a threshold function F(t) corresponding to the instructed transport speed. This makes it possible to select an appropriate threshold function F(t) and perform appropriate abnormality determination in response to differences in sound intensity levels due to transport speed.

[0079] Next, a third embodiment will be described. In the second embodiment, differences from the first embodiment will be described. Therefore, unless otherwise specified, the second embodiment may be the same as the first embodiment.

[0080] The range of possible sound intensity levels varies depending on the document size. Therefore, if the document size can be limited, the range will be narrowed, which will reduce variation and enable more accurate judgment.

[0081] Therefore, in the third embodiment, in order to derive the threshold function F(t), a group of audio data collected for each document size is generated. The controller 904 generates the threshold function F(t) for each document size by executing the processing procedure of Fig. 10 based on the group of audio data related to that document size, and records the generated threshold function F(t) in the ROM of the controller 904. Therefore, the threshold function F(t) for each document size is recorded in the ROM.

[0082] When the ADF 51 actually operates, the controller 904 executes the processing procedure shown in Fig. 6 using the threshold function F(t) corresponding to the document size of the document MS. This makes it possible to select an appropriate threshold function F(t) and to perform appropriate abnormality determination according to the difference in sound intensity level due to document size.

[0083] When the original MS is placed on the movable original table 56 and the original placement platen 53, the original length is detected by the first length sensor 57 and the second length sensor 58, and the original width is detected by the width sensor that detects the widthwise position of the side guides (not shown). In other words, the original size can be determined before the paper feeding / separating operation starts.

[0084] The third embodiment may be combined with the second embodiment, that is, a threshold function F(t) may be generated for each combination of conveying speed and document size.

[0085] Next, a fourth embodiment will be described. In the second embodiment, differences from the first embodiment will be described. Therefore, unless otherwise specified, the fourth embodiment may be the same as the first embodiment.

[0086] The range of possible sound intensity levels varies depending on the thickness of the original. Therefore, if the thickness of the original can be limited, this range will be narrowed, suppressing variation and enabling more accurate judgment.

[0087] The user inputs the thickness of the original by selecting from paper thickness mode options such as "plain paper," "thin paper," and "thick paper" on the main body operation unit 902. These paper thickness modes have a specified range of basis weights for the original.

[0088] Therefore, in the fourth embodiment, in order to derive the threshold function F(t), a group of voice data collected for each paper thickness mode (paper thickness setting) is generated using a plurality of documents that can be normally conveyed within the basis weight range of the paper thickness mode (paper thickness setting). For each paper thickness mode, the controller 904 generates the threshold function F(t) by executing the processing procedure of FIG. 10 based on the group of voice data related to the paper thickness mode, and records the generated threshold function F(t) in the ROM of the controller 904. Therefore, the threshold function F(t) is recorded in the ROM for each paper thickness mode.

[0089] When the ADF 51 actually operates, the main body control unit 901 notifies the ADF 51 of the paper thickness mode selected by the user. The controller 904 executes the processing procedure shown in Fig. 6 using the threshold function F(t) corresponding to the notified paper thickness mode (paper thickness setting). This makes it possible to select an appropriate threshold function F(t) and to perform appropriate abnormality judgment corresponding to differences in sound intensity levels due to the document paper thickness setting.

[0090] The fourth embodiment may be combined with the second or third embodiment. That is, a threshold function F(t) may be generated for each combination of the conveying speed and / or document size and the paper thickness mode.

[0091] In each of the above embodiments, the ADF 51 (particularly the separation feeding unit B) is an example of a transport unit. The sound collecting microphone 201 is an example of a sound collecting unit. The controller 904 is an example of a determining unit.

[0092] The functions of the above-described embodiments can be realized by one or more processing circuits. Here, the term "processing circuit" in this specification includes a processor programmed to execute each function by software, such as a processor implemented by an electronic circuit, as well as devices such as an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), and conventional circuit modules designed to execute each of the above-described functions.

[0093] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims.

[0094] For example, aspects of the present invention are as follows. <1> a conveying unit that conveys a document to be scanned; a sound collection unit that collects sounds generated during the period in which the document is transported; a determination unit that determines whether or not there is an abnormality in the transport of the document by comparing, in time series, first time-series data related to the sound with a threshold value that is set in time series for the period; and the threshold value is derived so that a region with a high occurrence frequency is more likely to be below the threshold value than a region with a low occurrence frequency in the second time-series data regarding the sound during the period for a plurality of documents that can be normally conveyed. The device characterized by: <2> the first time series data and the second time series data are time series data of sound intensity levels; Characterized by <1> The equipment described. <3> the threshold is derived for each divided period into which the period is divided, based on a probability density distribution of the sound intensity level corresponding to the divided period in the plurality of second time-series data. Characterized by <2> The equipment described. <4> the determination unit compares the sound intensity level of the time series indicated by the first time series data with a threshold value set in time series for the period, and determines the presence or absence of the abnormality based on the number of times the sound intensity level exceeds the threshold value. Characterized by <3> The equipment described. <5> The threshold value is set according to the conveying speed, the determination unit determines the presence or absence of the abnormality based on the threshold value corresponding to the conveying speed related to the first time-series data. Characterized by <1> ~ <4> 10. The device of any one of claims 1 to 9. <6> The threshold value is set according to the document size, the determination unit determines whether or not the abnormality exists based on the threshold value corresponding to the document size related to the first time-series data. Characterized by <1> ~ <5> 10. The device of any one of claims 1 to 9. <7> The threshold value is set according to the paper thickness setting, the determination unit determines whether or not the abnormality exists based on the threshold value corresponding to the paper thickness setting related to the first time-series data. Characterized by <1> ~ <6> 10. The device of any one of claims 1 to 9. <8> a transport procedure for transporting a document to be scanned; a sound collection procedure for collecting sounds generated during the period in which the document is transported; a determination step of determining whether or not there is an abnormality in the transport of the document by comparing, in time series, first time-series data related to the sound with a threshold value set in time series for the period; The equipment runs, the threshold value is derived so that a region with a high occurrence frequency is more likely to be below the threshold value than a region with a low occurrence frequency in the second time-series data regarding the sound during the period for a plurality of documents that can be normally conveyed. An abnormality determination method comprising: [Explanation of symbols]

[0095] 1 Image forming unit 40 Sheet feeding device 50 Image reading system 51 Automatic Document Feeder (ADF) 53 Document stand 54 Transport unit 56 Movable manuscript table 57 First length sensor 58 Second length sensor 61 Paper ejection sensor 63 Document set sensor 65 Resist Sensor 67 Reading entrance sensor 72 Push-button sensor 73 Document width sensor 100 copiers 150 scanner 151 First surface fixed reading unit 152 Mobile reading unit 153 Image reading sensor 154 First contact glass 155 Second contact glass 191 Paper feed motor 192 Transport motor 193 Pull-out clutch 194 Paper discharge clutch 201 Sound collection microphone 901 Main unit control section 903 Reading control unit 904 Controller A Original setting area B Separation feeding section C Resist section D turn section E First reading and conveying section F Second reading and transport section G Paper output section H stack section [Prior art documents] [Patent documents]

[0096] [Patent Document 1] Japanese Patent Application Publication No. 2019-142647

Claims

1. a conveying unit that conveys a document to be scanned; a sound collection unit that collects sounds generated during the period in which the document is transported; a determination unit that determines whether or not there is an abnormality in the transport of the document by comparing, in time series, first time-series data related to the sound with a threshold value that is set in time series for the period; and the threshold value is derived so that a region with a high occurrence frequency is included more frequently than a region with a low occurrence frequency in the second time-series data regarding the sound during the period for a plurality of documents that can be normally conveyed, the region being included more frequently than the threshold value. The device characterized by:

2. the first time series data and the second time series data are time series data of sound intensity levels; 2. The device of claim 1.

3. the threshold is derived for each divided period into which the period is divided, based on a probability density distribution of the sound intensity level corresponding to the divided period in the plurality of second time-series data.

3. The device according to claim 2.

4. the determination unit compares the sound intensity level of the time series indicated by the first time series data with a threshold value set in time series for the period, and determines the presence or absence of the abnormality based on the number of times the sound intensity level exceeds the threshold value.

4. The device of claim 3.

5. The threshold value is set according to the conveying speed, the determination unit determines the presence or absence of the abnormality based on the threshold value corresponding to the conveying speed related to the first time-series data.

5. Device according to any one of claims 1 to 4, characterized in that it comprises:

6. The threshold value is set according to the document size, the determination unit determines whether or not the abnormality exists based on the threshold value corresponding to the document size related to the first time-series data.

5. Device according to any one of claims 1 to 4, characterized in that it comprises:

7. The threshold value is set according to the paper thickness setting, the determination unit determines whether or not the abnormality exists based on the threshold value corresponding to the paper thickness setting related to the first time-series data.

5. Device according to any one of claims 1 to 4, characterized in that it comprises:

8. a transport procedure for transporting a document to be scanned; a sound collection procedure for collecting sounds generated during the period in which the document is transported; a determination step of determining whether or not there is an abnormality in the transport of the document by comparing, in time series, first time-series data related to the sound with a threshold value set in time series for the period; The equipment runs, the threshold value is derived so that a region with a high occurrence frequency is included more frequently than a region with a low occurrence frequency in the second time-series data regarding the sound during the period for a plurality of documents that can be normally conveyed, the region being included more frequently than the threshold value. An abnormality determination method comprising:

Images