JP2019108193A - Image forming apparatus, image forming method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus, an image forming method, and a program capable of detecting an abnormality of a double feeding detecting unit for detecting double feeding of a sheet. An image forming apparatus (10) includes a sheet mounting unit (11), a transport processing unit (1), and a double feed detection sensor (8) provided at a measurement position (P1) on a transport path (12) to detect double feed of a sheet (S1). , The first measured value L1 measured by the double feed detection sensor 8 when the sheet S1 is not present at the measurement position P1 and the second measured value L1 measured by the double feed detection sensor 8 when the sheet S1 is present at the measurement position P1. Abnormality determination for determining that an abnormality has occurred in the double feed detection sensor 8 when the measurement value acquisition unit 51 for acquiring the measurement value L2 and the first measurement value L1 exceed the preset first threshold value Lt1. A unit 53 and a double feed determination unit 52 for determining whether or not double feed of the sheet S1 has occurred based on the second measured value L2 are provided. [Selection diagram] FIG. 9

Description

  The present invention relates to an image forming apparatus, an image forming method, and a program.

  In an image forming apparatus such as a scanner apparatus, a copier, or a multifunction machine having a scanning function and a copying function, so-called multi-feed occurs in which a plurality of sheets are overlapped and conveyed by a sheet conveying apparatus that conveys sheets such as sheets. There is a case. For example, if double feeding occurs during scan processing, various problems may occur such as an image reading failure in the image reading unit or a sheet jamming in the transport path. Conventionally, techniques for detecting double feeding of sheets have been proposed. For example, Patent Document 1 discloses a double feed detection device that detects double feed by measuring the state of a sheet using an ultrasonic sensor.

Patent No. 3752228

  By the way, since the double feed detection unit such as an ultrasonic sensor for detecting double feed is generally disposed at a position close to the conveyance path, foreign matter such as paper dust is detected from the conveyed sheet. There is a problem that it adheres to the detection surface of the part and the detection surface is soiled. If an abnormality occurs in the double feed detection unit, such as the detection surface of the double feed detection unit becoming dirty, it becomes difficult to appropriately determine the double feed. In the above-described conventional double feed detection device, since the abnormality (such as dirt) of the ultrasonic sensor itself is not considered, there is a possibility that the determination of double feed may be erroneous.

  An object of the present invention is to provide an image forming apparatus, an image forming method, and a program capable of detecting an abnormality in a double feed detection unit for detecting double feeding of sheets.

  An image forming apparatus according to one aspect of the present invention includes a sheet placement unit, a conveyance processing unit, a double feed detection unit, a measurement value acquisition unit, an abnormality determination unit, and a double feed determination unit. The transport processing unit sequentially transports a plurality of sheets placed on the sheet placement unit. The double feed detection unit detects double feed of the sheets provided at a predetermined measurement position on the conveyance path of the sheets. The measurement value acquisition unit acquires a first measurement value measured by the double feed detection unit in a state where the sheet is not present at the measurement position, and the double feed in a state where the sheet is present at the measurement position The second measurement value measured by the detection unit is acquired. The abnormality determination unit determines that the double feed detection unit has an abnormality when the first measurement value acquired by the measurement value acquisition unit exceeds a preset first threshold. The double feed determination unit determines whether double feeding of the sheet occurs based on the second measurement value acquired by the measurement value acquisition unit.

  According to another aspect of the present invention, an image forming method includes: a sheet placement unit; a conveyance processing unit configured to sequentially convey a plurality of sheets placed on the sheet placement unit; And a double feed detection unit for detecting double feed of the sheet, provided at the measured position, and an image forming method in an image forming apparatus. Then, the image forming method acquires the first measurement value measured by the double feed detection unit in the state where the sheet is not present at the measurement position, and the weight is obtained when the sheet is present at the measurement position. Acquisition of the second measurement value measured by the feed detection unit, and when the acquired first measurement value exceeds a preset first threshold, an abnormality occurs in the double feed detection unit And determining whether double feeding of the sheet has occurred based on the acquired second measurement value.

  A program according to another aspect of the present invention is a double feed detection unit for detecting double feed of the sheet in a state where the sheet transported on the transport path does not exist at a predetermined measurement position on the transport path. Acquiring a first measurement value measured by the step of acquiring a second measurement value measured by the double feed detection unit in a state where the sheet is present at the measurement position; and When the measured value exceeds a preset first threshold value, it is determined that the double feed detection unit has an abnormality, and the sheet is determined based on the acquired second measured value. Determining whether or not double feeding has occurred, and a program for causing a computer to execute.

  According to the present invention, it is possible to provide an image forming apparatus, an image forming method, and a program capable of detecting an abnormality in a double feed detection unit for detecting double feed of sheets.

FIG. 1 is a schematic cross-sectional view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a schematic configuration of a main part of the ADF (automatic document feeder) shown in FIG. FIG. 3 is a functional block diagram showing functions of the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a table showing the relationship between the preset reception level and the double feed threshold according to the embodiment of the present invention. FIG. 5 is a graph showing an example of the relationship between the number of sheets read by a scan operation and the reception level according to the embodiment of the present invention. FIG. 6 is a graph showing another example of the relationship between the number of sheets read by a scan operation and the reception level according to the embodiment of the present invention. FIG. 7 is a diagram showing an example of the display unit notified to the user according to the embodiment of the present invention. FIG. 8 is a diagram showing another example of the display unit notified to the user according to the embodiment of the present invention. FIG. 9 is a flowchart for explaining an example of the procedure of scan processing according to the embodiment of the present invention. FIG. 10 is a flowchart for explaining another example of the procedure of scan processing according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

  The image forming apparatus according to the present invention has, for example, a scan function of reading image data from a sheet (such as an original), a print function of forming an image based on image data acquired from the outside, a facsimile function, and a plurality of functions such as a copy function. It is a multifunction machine having The image forming apparatus according to the present invention is applicable to a scanner device, a printer device, a facsimile device, a copier, and the like. In the following, among the plurality of functions of the image forming apparatus 10 as a multifunction peripheral, a scan function will be described as an example.

  As shown in FIGS. 1 to 3, the image forming apparatus 10 mainly includes an ADF 1 (automatic document feeder: transport processing unit), an image reading unit 2, an image forming unit 3, a paper feeding unit 4, a control unit 5, The operation display unit 6 and the storage unit 7 are provided.

  The operation display unit 6 receives an operation of the user and inputs an operation key such as an operation key or a touch panel for inputting various information according to the operation to the control unit 5, and an instruction output from the control unit 5. And a display unit such as a liquid crystal display for displaying various information. For example, when the user performs a scan operation on the operation display unit 6, information corresponding to the scan operation is input to the control unit 5. The control unit 5 executes a scan process (described later) including various processes according to the scan operation. The user may perform various operations using a user terminal connected to the network via the communication unit 300.

  The ADF 1 includes a sheet placement unit 11, a conveyance path 12, conveyance rollers 13 to 15, a sheet guide 16, and a discharge tray 17. The ADF 1 is controlled by the control unit 5 to sequentially transport the plurality of sheets S 1 placed on the sheet placement unit 11. The conveyance path 12 is a movement passage of the sheet S1 conveyed by the ADF 1, and is formed by a pair of conveyance guide members. The conveyance rollers 13 to 15 are provided on the conveyance path 12. Each of the transport rollers 13 to 15 is driven by a motor (not shown) whose drive is controlled by the control unit 5 to sequentially transport the plurality of sheets S1 placed on the sheet placement unit 11 Transport in the direction D1 (see FIG. 2). The sheet guide 16 guides the sheet S <b> 1 conveyed by the conveyance roller 14 onto the contact glass 211 of the sheet table 21. The conveyance roller 15 discharges the sheet S <b> 1 on which the image reading process is performed by the image reading unit 2 in the sheet table 21 from the conveyance path 12 to the discharge tray 17.

  Further, a double feed detection sensor 8 (double feed detection unit) described later is provided on the conveyance path of the ADF 1.

  The image reading unit 2 is controlled by the control unit 5 to execute an image reading process of reading an image from the sheet S1 guided to the contact glass 211 by the ADF 1. The image reading unit 2 can apply a known configuration. For example, as shown in FIG. 1, the image reading unit 2 includes a seed table 21, a reading unit 22, mirrors 23 and 24, an optical lens 25, and a CCD 26. The sheet table 21 is provided on the top surface of the case of the image forming apparatus 10.

  The reading unit 22 is provided below the contact glass 211. The reading unit 22 is configured to be movable in the sub-scanning direction (the left and right direction in FIG. 1) by a moving mechanism (not shown) having a drive unit such as a stepping motor. For example, the reading unit 22 is moved to the position facing the sheet guide 16 of the ADF 1 by the moving mechanism. The reading unit 22 includes a light source 221 and a mirror 222.

  The light sources 221 are, for example, a plurality of white LEDs arranged along the main scanning direction (the paper surface depth direction in FIG. 1). The light source 221 emits white light for one line in the main scanning direction toward the contact glass 211. The light emitted from the light source 221 passes through the contact glass 211 and is irradiated to the sheet S1 conveyed by the ADF 1.

  In the mirror 222, light emitted from the light source 221 and reflected by the sheet S 1 is repeatedly reflected by the mirrors 222, 23 and 24, and is incident on the optical lens 25. The optical lens 25 condenses the incident light and emits it to the CCD 26. The CCD 26 (image sensor) outputs an electrical signal (analog signal) according to the amount of light received. An analog signal output from the CCD 26 is converted to a digital signal (image data) and input to the control unit 5. The image reading unit 2 reads an image of a sheet as image data by the above processing.

  The storage unit 7 is a storage device such as a solid state drive (SSD) or a hard disk drive (HDD). The storage unit 7 includes an image data storage unit 71, a first measurement value storage unit 72, and a second measurement value storage unit 73. For example, the image data storage unit 71 stores image data read by the image reading unit 2. In each of the first measurement value storage unit 72 and the second measurement value storage unit 73, each of a first measurement value L1 and a second measurement value L2, which will be described later, measured by the double feed detection sensor 8 is stored.

  The double feed detection sensor 8 (double feed detection unit) is an ultrasonic sensor that detects double feed of the sheet S <b> 1 conveyed by the conveyance roller 13 from the sheet placement unit 11. Here, the double feeding refers to a state in which a plurality of sheets S1 are conveyed from the sheet placement unit 11 in an overlapping manner. When the double feeding occurs, various problems such as an image reading failure in the image reading unit 2 or a jamming of the sheet S1 in the conveyance path 12 may occur.

  As shown in FIG. 2, the double feed detection sensor 8 is a transmitting unit 8a disposed opposite to sandwich the sheet S1 moving in the conveyance path 12 at a predetermined position (measurement position P1) on the conveyance path 12. And a receiver 8b. The transmitting unit 8a transmits an ultrasonic wave, and the receiving unit 8b outputs an electrical signal corresponding to the intensity of the received ultrasonic wave to the control unit 5 (double-feed measurement process). The double feed detection sensor 8 may be a transmission type light sensor. In this case, the double feed detection sensor 8 outputs an electric signal corresponding to the light amount to the control unit 5.

  The double feed detection sensor 8 executes the double feed measurement process at a predetermined timing (first timing). Specifically, the double feed detection sensor 8 executes the double feed measurement process in a state where the sheet S1 is not present between the transmission unit 9a and the receiving unit 9b of the double feed detection sensor 8 (measurement position P1 in FIG. 2). Do. For example, the double feed detection sensor 8 executes the double feed measurement process from when the user receives a scan operation until when the conveyance of the sheet S1 is started. The double feed detection sensor 8 outputs the measurement value measured at the first timing to the control unit 5 as a first measurement value L1.

  The double feed detection sensor 8 executes the double feed measurement process in a state where the sheet S1 is present at the measurement position P1 of the double feed detection sensor 8. For example, the double feed detection sensor 8 may execute the double feed measurement process at a timing (second timing) at which the sensor S or the like (not shown) detects that the sheet S1 has reached the measurement position P1. The double feed measurement process may be performed at a timing (second timing) at which a known time until the sheet S1 reaches the measurement position P1 elapses after the user receives a scan operation. The double feed detection sensor 8 outputs the measurement value measured at the second timing to the control unit 5 as a second measurement value L2.

  The control unit 5 performs a double feed determination process of detecting double feeding of the sheet S1 transported by the transport roller 13 from the sheet placement unit 11, an abnormality determination process of detecting an abnormality of the double feed detection sensor 8, and a double feed detection. A notification process of notifying the user of an abnormality of the sensor 8 is executed.

  The control unit 5 includes a CPU, a ROM, a RAM, and the like. The control unit 5 also includes a non-volatile storage unit (not shown) such as an EEPROM (registered trademark). Then, the control unit 5 controls the image forming apparatus 10 by causing the CPU to execute processing according to a program stored in the ROM, the storage unit or the like. Specifically, as shown in FIG. 3, the control unit 5 includes a measurement value acquisition unit 51, a double feed determination unit 52, an abnormality determination unit 53, and a notification processing unit 54. The control unit 5 functions as the measurement value acquisition unit 51, the double feed determination unit 52, the abnormality determination unit 53, and the notification processing unit 54 by the CPU executing processing according to the program stored in the ROM. . Note that any one or more of the measurement value acquisition unit 51, the double feed determination unit 52, the abnormality determination unit 53, and the notification processing unit 54 may be an electronic circuit such as an ASIC. The program may be stored in a computer-readable storage medium such as a CD-ROM, a DVD-ROM, or a memory card, and may be installed in the image forming apparatus 10 from the storage medium, or a communication network such as the Internet May be downloaded from

  The measurement value acquisition unit 51 acquires the first measurement value L1 and the second measurement value L2 measured by the double feed detection sensor 8 at the first timing and the second timing. The measured value acquiring unit 51 stores the acquired first measured value L1 in the first measured value storage unit 72 of the storage unit 7, and the acquired second measured value L2 in the second measured value storage unit 73 of the storage unit 7. Remember.

  The double feed determination unit 52 determines the presence or absence of double feed based on the second measurement value L2 acquired by the measurement value acquisition unit 51 (double transmission determination process). Specifically, when the double feed determination unit 52 exceeds the threshold (hereinafter referred to as “double feed threshold Lt2”) (second threshold) in which the reception level corresponding to the second measurement value L2 is set in advance. It is determined that double feed has occurred. FIG. 4 is a table showing the relationship between the preset reception level and the double feed threshold Lt 2 (here, “reception level” is the output voltage value of the double feed detection sensor 8 normalized to 256 values. So, the higher this value, the lower the output voltage value of the double feed detection sensor). This table is stored in the storage unit 7, and the setting information of the table can be changed as appropriate. For example, the reception level for one sheet S1 is set to "101" to "200", and the reception level for two or more sheets S1 (double feed) is set to "201" to "255". ing. Further, the reception level when the sheet S1 does not exist is set to “0” to “100”. That is, in the example shown in FIG. 4, the double feed threshold Lt2 is set to "200". In the example shown in FIG. 4, the reception level is set to three levels, but is not limited to this.

  If it is determined in the double feed determination process that a double feed occurs, the control unit 5 executes a process (double feed cancellation process) for canceling the double feed. For example, the control unit 5 may perform processing for temporarily stopping conveyance of the sheet S1, or the other sheet S1 (multi-feeding sheet) overlapping the original sheet S1 may be discharged from the discharge tray 17 or the sheet evacuation tray (see FIG. You may perform the process discharged | emitted to (not shown).

  Here, when the scan operation is performed in the image forming apparatus 10, foreign matter such as paper dust is generated from the sheet S1, and it adheres to the detection surface of the double feed detection sensor 8 and there is a problem that the detection surface is soiled. . In an ideal state where the detection surface of the double feed detection sensor 8 is not soiled, the reception level of the double feed detection sensor 8 is “0”, and the double feed of the detection surface of the double feed detection sensor 8 becomes high. The reception level of the detection sensor 8 is high. Contamination on the detection surface of the double feed detection sensor 8 is accumulated in accordance with the frequency of use, so that the reception level becomes high as the number of readings (number of times) by the scanning operation increases as shown in FIG. 5, for example. Further, for example, when an unexpected stain is attached to a specific sheet S1, as shown in FIG. 6, the reception level of the double feed detection sensor 8 suddenly increases suddenly.

  Therefore, the image forming apparatus 10 has a function of detecting an abnormality (for example, dirt on the detection surface) of the double feed detection sensor 8 and notifying the user of the detected abnormality.

  Specifically, in the abnormality determination unit 53, the first measurement value L1 acquired by the measurement value acquisition unit 51 exceeds a preset threshold (hereinafter referred to as "abnormality threshold Lt1") (first threshold). When it is determined that the double feed detection sensor 8 has an abnormality, it is determined. Here, the abnormal threshold Lt1 is set to a value lower than a value (hereinafter referred to as "single-feed threshold Lt0") which is a boundary between the reception level in the absence of the sheet S1 and the reception level in the sheet S1. It is set. For example, in the example shown in FIG. 4, since the single transmission threshold Lt0 is set to "100", the abnormality threshold Lt1 is set to "75". The abnormality determination unit 53 determines that the double feed detection sensor 8 is abnormal when the first measurement value L1 exceeds the abnormality threshold Lt1 (= “75”). As a result, it is possible to detect an abnormality in the double feed detection sensor 8 before erroneously detecting that there is only one sheet S1 due to an increase in the reception level despite the absence of the sheet S1.

  The notification processing unit 54 notifies the user of a message indicating that the double feed detection sensor 8 has an abnormality, when the abnormality determination unit 53 determines that the double feed detection sensor 8 has an abnormality. For example, the notification processing unit 54 displays a message shown in FIG. 7 on the display unit (liquid crystal display) of the operation display unit 6 to urge the user to clean the detection surface of the double feed detection sensor 8.

<Scan processing>
Hereinafter, an example of the procedure of the scan process including the abnormality determination process and the notification process performed by the control unit 5 in the image forming apparatus 10 will be described with reference to the flowchart of FIG. In addition, each processing process performed by the control part 5 is called step S11, S12 ,. For example, the abnormality determination process is performed when the user instructs the image forming apparatus 10 to perform a scan operation.

  First, in step S11, the control unit 5 acquires an instruction of a scan operation by the user via the operation display unit 6. Next, in step S12, the double feed detection sensor 8 performs ultrasonic measurement at a first timing (during the start of conveyance of the sheet S1) based on an instruction of the control unit 5. That is, ultrasonic measurement is performed in a state where the sheet S1 is not present at the measurement position P1. Next, in step S13, the measurement value acquisition unit 51 acquires a first measurement value L1 measured by the double feed detection sensor 8. The measurement value acquisition unit 51 stores the acquired first measurement value L1 in the first measurement value storage unit 72 of the storage unit 7.

  Next, in step S14, the abnormality determination unit 53 determines whether or not the first measurement value L1 exceeds the preset abnormality threshold Lt1. If the first measurement value L1 exceeds the abnormality threshold Lt1 (S14: YES), the abnormality determination unit 53 determines that the double feed detection sensor 8 has an abnormality, and in S15, the notification processing unit 54 Notify the user of the message etc. (Fig. 7). Thereafter, in step S16, the process proceeds to maintenance processing.

  In the maintenance process, for example, the user is urged to perform maintenance work (for example, cleaning work of the detection surface of the double feed detection sensor 8) on the display screen shown in FIG. 7, and the end of the maintenance work is accepted. When the end of the maintenance work by the user is input (for example, pressing the "OK" button), the process returns to step S12, and the double feed detection sensor 8 performs ultrasonic measurement again, and the measurement value acquisition unit 51 performs the first measurement. Get the value L1. The measurement value acquisition unit 51 updates the first measurement value L1 stored last time in the first measurement value storage unit 72 to the first measurement value L1 acquired this time. Thereafter, the process of steps S12 to S16 is repeated until the first measurement value L1 falls below the abnormal threshold Lt1. If the first measurement value L1 still exceeds the abnormal threshold Lt1 even if the maintenance work is performed multiple times, the user is prompted to request the repair contractor when the maintenance work has reached a predetermined number of times. It may be notified.

  Further, in S15, after the notification processing unit 54 notifies the user (FIG. 7) of the message and the like (FIG. 7), the process proceeds to S17 without shifting to the maintenance process of step S16, and the normal scan process (image reading process) You may start

  Further, the notification to the user of the message or the like (FIG. 7) in S15 and the maintenance process in step S16 may be performed when the scanning operation is completed.

  In step S14, when the first measurement value L1 does not exceed the abnormal threshold Lt1 (S14: NO), the process proceeds to S17, and normal scan processing (image reading processing) is started. Specifically, when the sheet S1 conveyed from the sheet placement unit 11 reaches the measurement position P1 (step S17: YES), the double feed detection sensor 8 performs ultrasonic measurement in step S18. That is, ultrasonic measurement is performed in a state where the sheet S1 is present at the measurement position P1. Next, in step S19, the measurement value acquisition unit 51 acquires a second measurement value L2 measured by the double feed detection sensor 8. The measurement value acquisition unit 51 stores the acquired second measurement value L2 in the second measurement value storage unit 73 of the storage unit 7.

  Next, in step S20, the double feed determination unit 52 determines whether the second measurement value L2 exceeds the preset double feed threshold Lt2. If the second measurement value L2 does not exceed the double feed threshold Lt2 (S20: NO), the sheet S1 is conveyed by the conveyance rollers 13 and 14 and guided onto the contact glass 211 of the sheet table 21 in step S21. The image reading unit 2 executes the image reading process and ends the scanning process.

  If the second measurement value L2 exceeds the double feed threshold Lt2 (S20: YES), it is determined that double feed occurs, and in step S22, the double feed cancellation process is executed to complete the scan process. Note that after the multi-feed cancellation process is completed in step S22, the process may return to step S20.

  According to the image forming apparatus 10 having the above-described configuration, the user can grasp the abnormality of the double feed detection sensor 8 at an early stage, so that maintenance can be appropriately performed. For this reason, it is possible to suppress false detection of double feeding caused by an abnormality in double feeding detection sensor 8. In addition, since the user can perform an early maintenance operation, the number of dispatches of the repair company can be reduced. Furthermore, since an abnormality in the double feed detection sensor 8 can be detected using a measurement result of the double feed detection sensor 8 itself, an additional component (dedicated device) for detecting an abnormality in the double feed detection sensor 8 There is no need to prepare Therefore, the abnormality in the double feed detection sensor 8 can be easily detected without complicating the configuration of the image forming apparatus 10.

  The image forming apparatus according to the present invention is not limited to the above-described configuration. For example, the abnormality determination unit 53 may have the following configuration (modification).

  For example, in the image forming apparatus 10, the abnormality determination unit 53 detects double feeding based on the current first measurement value L1 and the amount of change in the first measurement value L1 due to the number (number of times) of reading in the past scan operation. An abnormality of the sensor 8 may be determined. For example, the abnormality determination unit 53 determines that the number (number of times) of the number of sheets read by a future scan operation is a boundary between the reception level in the absence of the sheet S1 and the reception level in the presence of one sheet S1. The number of sheets (number of times) read by the scan operation expected to reach the single feed threshold Lt0 is determined, and when the number of read sheets is less than the preset number (number of threshold sheets), the double feed detection sensor 8 has an abnormality. It is determined that there is. Specifically, for example, the number of sheets (the threshold number of sheets) set in advance is set to "100", and when the number of sheets to be read is 0, the reception level at the double feed detection sensor 8 is "0," and the number of sheets to be read is 1000 It is assumed that the reception level at the double feed detection sensor 8 rises from "0" to "50" when the number of sheets is one. In this case, the increase value of the reception level per sheet is calculated as “0.05”. When the reception level of the single transmission threshold Lt0 is set to "100", the number of read sheets expected to become the single transmission threshold Lt0 "100" from the current first measured value L1 (50) is "1000". And calculated (= (100−50) ÷ 0.05). Here, since the predicted number of read sheets is larger than the threshold number “100 sheets”, the abnormality determination unit 53 does not determine that the double feed detection sensor 8 has an abnormality.

Further, for example, it is assumed that the reception level at the double feed detection sensor 8 rises from “0” to “95” when the number of read sheets is 1900. In this case, the increase value of the reception level per sheet is calculated as “0.05”. From the current first measured value L1 (95), the number of read sheets expected to become the single-feed threshold Lt0 "100" is calculated as "100" (= (100-95) / 0.05). Here, since the number of readings expected is larger than the threshold number of sheets “100”, the abnormality determining unit 53 determines that the double feed detection sensor 8 has an abnormality.
The number of read sheets may be measured by a counter 9 (see FIG. 3) provided in the image forming apparatus 10 or may be measured by an optical sensor (not shown) provided on the conveyance path 12.

  Further, in the above example, the abnormality determination unit 53 may determine the abnormality of the double feed detection sensor 8 based on the reception level. For example, the reception level when the number of sheets read by the scan operation reaches the threshold number of sheets (“1900 sheets”) is calculated as “95” (= 1900 × 0.05). Therefore, when the first measurement value L1 exceeds the reception level "95", the abnormality determination unit 53 may determine that the double feed detection sensor 8 has an abnormality.

  As another modification, for example, in the image forming apparatus 10, the abnormality determination unit 53 determines the abnormality of the double feed detection sensor 8 based on the increase rate of the first measurement value L1 measured by the double feed detection sensor 8. You may judge. For example, it is assumed that the reception level at the double feed detection sensor 8 increases by "0.05" per sheet. In this case, when the reception level rises by “5.0” or more compared to the previous time, the abnormality determination unit 53 determines that the double feed detection sensor 8 has an abnormality. This configuration is suitable for the case where the sheet itself contains some abnormality, for example, when a sheet with many stains is scanned.

  By the way, in the above-mentioned configuration, when the first measurement value L1 does not exceed the abnormal threshold Lt1 (S14 in FIG. 9: NO), the second measurement value L2 is actually in spite of the fact that double feeding does not occur. If the double feed threshold Lt2 is exceeded (S20: YES), it may be falsely detected that double feed occurs. For example, it is assumed that the reception level of the double feed detection sensor 8 in the case where double feed does not occur is "180" in one sheet S1 including some stains. In this case, if the first measurement value L1 is, for example, "60", the second measurement value L2 is "240", and it is determined that double feeding has occurred. As described above, even if one sheet is actually used, it may be considered that the determination of double feeding may not be accurately performed due to the sheet characteristics such as the thickness and the degree of contamination of the sheet.

  Therefore, the image forming apparatus 10 may further include a configuration (correction process) for correcting the variation of the measurement value due to the characteristics of the sheet S1. Specifically, as shown in FIG. 10, the double feed determination unit 52 corrects the second measurement value L2 to a value (correction value L3) obtained by subtracting the first measurement value L1 from the second measurement value L2 (a correction value L3). S31) It is determined whether the correction value L3 has exceeded the double feed threshold Lt2 (S32). If the correction value L3 does not exceed the double feed threshold Lt2 (S32: NO), it is determined that double feed has not occurred, and the process proceeds to S21 to execute the image reading process. On the other hand, if the correction value L3 exceeds the double feed threshold Lt2 (S32: YES), it is determined that double feed occurs, and the process proceeds to step S22 to execute the double feed cancellation process. By performing the correction process, it is possible to more accurately determine double feeding.

  Other configurations (modifications) of the image forming apparatus 10 will be further listed below.

  In the example described above, when the image forming apparatus 10 detects an abnormality in the double feed detection sensor 8, the user is notified of a message to the effect that an abnormality has occurred in the double feed detection sensor 8, but the present invention The image forming apparatus is not limited to this. For example, when the image forming apparatus 10 includes a cleaning device (not shown) whose driving is controlled by the control unit 5 and detects an abnormality in the double feed detection sensor 8, the cleaning device detects the double feed detection sensor 8. The surface may be cleaned. Thereby, the effort of the maintenance work by a user can be saved.

  Further, in the above-described example, the scan function is taken as an example of the plurality of functions of the image forming apparatus 10, but the image forming apparatus of the present invention is not limited to this. For example, the double feed measurement process, the abnormality determination process, and the notification process described above can also be applied to the copy function that the image forming apparatus 10 has. Further, each of the processes can be applied to a copying machine. Specifically, as shown in FIG. 1, in the image forming apparatus 10, the double feed detection sensor 44 (for example, an ultrasonic sensor) (double feed detection unit) is configured to place the sheet S2 placed on the sheet feeding cassette 41. The image forming unit 3 may be provided in the sheet feeding unit 4 that conveys the image. More specifically, the double feed detection sensor 44 is disposed close to the downstream side of the transport roller 43 provided downstream of the pickup roller 42. The double feed detection sensor 44 executes the double feed measurement process at a predetermined timing based on an instruction of the control unit 5. The control unit 5 acquires the measurement values (first measurement value, second measurement value) by the double feed detection sensor 44, and executes the abnormality determination process and the notification process. When the controller 5 detects an abnormality in the double feed detection sensor 44, the controller 5 notifies the user of a message (see FIGS. 7 and 8) to that effect. As a result, it is possible to notify the user of an abnormality in the double feed detection sensor 44 in the image formation process.

  Further, in the above-described example, the message etc. is displayed on the operation display unit 6 of the image forming apparatus, but the reception level is periodically (for every one sheet, one job, predetermined number of sheets) to the server etc via the communication unit 300 , And the server may process the reception level data to display data as shown in FIG. 8 on the server or the user terminal. Here, in FIG. 8, the present reception level, a graph of the change in the reception level according to the number, and the number (number of times) of readings by the scan operation expected to reach the single delivery threshold Lt0 are displayed.

  Moreover, in the above-mentioned example, although adhesion of foreign materials, such as paper dust, was mentioned as a cause of abnormality of a double feed detection sensor, the cause of abnormality of a double feed detection sensor is not limited to this. The cause of the abnormality of the double feed detection sensor may be, for example, a contact failure of the double feed detection sensor or a defect due to the influence of the surrounding environment (temperature, humidity, atmospheric pressure, etc.).

  Further, although the double feed detection sensor has been described in the above-described example, the above-described processes can be applied to other sensors provided in the image forming apparatus 10. For example, the present invention can be applied to an optical sensor for determining the type of sheet (paper type).

  In the example described above, an example in which the determination of the abnormality of the double feed detection sensor and the determination of the double feed is given according to the reception level measured by the double feed detection sensor, the present invention is not limited thereto. For example, the abnormality determination unit 53 and the double feed determination unit 52 may perform the determination of the abnormality and the determination of the double feed based on the attenuation amount according to the number of passing ultrasonic waves passing through the sheet. In this case, as the degree of contamination on the detection surface of the double feed detection sensor 8 increases, the attenuation amount of ultrasonic waves of the double feed detection sensor 8 increases, and as the number of sheets increases, the ultrasonic waves of the double feed detection sensor 8 The amount of attenuation of

1 ADF
11 sheet placement unit 12 conveyance path 2 image reading unit 3 image forming unit 4 sheet feeding unit 44 double feeding detection sensor 5 control unit 51 measurement value acquiring unit 52 double feeding determination unit 53 abnormality determination unit 54 notification processing unit 6 operation display unit 7 storage unit 8 double feed detection sensor 9 counter 10 image forming apparatus

Claims (9)

A sheet placement unit,
A conveyance processing unit that sequentially conveys a plurality of sheets placed on the sheet placement unit;
A double feed detection unit provided at a predetermined measurement position on a conveyance path of the sheet and detecting double feed of the sheet;
A first measurement value measured by the double feed detection unit in a state where the sheet is not present at the measurement position is acquired, and a second measurement is performed by the double feed detection unit in a state where the sheet is present at the measurement position 2 Measured value acquisition unit for acquiring measured values,
An abnormality determination unit that determines that an abnormality has occurred in the double feed detection unit when the first measurement value acquired by the measurement value acquisition unit exceeds a preset first threshold;
A double feed determination unit that determines whether double feeding of the sheet occurs based on the second measurement value acquired by the measurement value acquisition unit;
An image forming apparatus comprising: A notification unit for notifying a user of the image forming apparatus of a message indicating that the double feed detection unit is abnormal when it is determined by the abnormality determination unit that the double feed detection unit is abnormal; Furthermore,
An image forming apparatus according to claim 1. The abnormality determination unit is configured to read in advance the number of sheets read by a scan operation expected to reach a threshold which is a boundary between the reception level in the absence of the sheet and the reception level in the presence of one sheet. When the number of sheets is less than the set number, it is determined that an abnormality has occurred in the double feed detection unit,
The image forming apparatus according to claim 1. The abnormality determination unit determines an abnormality of the double feed detection unit based on an increase rate of the first measurement value measured by the double feed detection unit.
The image forming apparatus according to claim 1. The double feed detection unit performs measurement on the measurement position before conveyance of the sheet is started.
The image forming apparatus according to any one of claims 1 to 4. It further comprises a storage unit for storing the first measurement value,
The measurement value acquisition unit updates the past first measurement value stored in the storage unit each time the first measurement value is acquired from the double feed detection unit.
The image forming apparatus according to any one of claims 1 to 5. The double feed detection unit is an ultrasonic sensor including a transmission unit that transmits ultrasonic waves and a reception unit that receives the ultrasonic waves transmitted from the transmission unit.
The image forming apparatus according to any one of claims 1 to 6. A sheet placement unit, a conveyance processing unit for sequentially conveying a plurality of sheets placed on the sheet placement unit, and a weight of the sheet provided at a predetermined measurement position on a conveyance path of the sheet An image forming method in an image forming apparatus comprising: a double feed detection unit for detecting a feed;
While acquiring the first measurement value measured by the double feed detection unit in the state where the sheet is not present at the measurement position, the first measurement value measured by the double feed detection unit in the state where the sheet is present at the measurement position 2 to obtain measured values,
When the acquired first measurement value exceeds a preset first threshold, it is determined that the double feed detection unit has an abnormality;
Determining whether double feeding of the sheet has occurred based on the acquired second measurement value;
An image forming method including: The first measurement value measured by the double feed detection unit for detecting double feeding of the sheet is acquired in a state in which the sheet transported on the transport path does not exist at a predetermined measurement position on the transport path. Step and
Acquiring a second measurement value measured by the double feed detection unit in a state where the sheet is present at the measurement position;
Determining that an abnormality has occurred in the double feed detection unit when the acquired first measurement value exceeds a preset first threshold value;
Determining whether double feeding of the sheet has occurred based on the acquired second measurement value;
A program that causes a computer to execute.

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