JP2006248701A - Sheet material conveying device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent false detection of double feed occurring in conveying a punched sheet material. <P>SOLUTION: The sheet material conveying device 10 is provided with an optical sensor 66 arranged on an upstream side of an ultrasonic sensor 60 in a conveying direction, which detects a hole H passing a search range of the ultrasonic sensor 60. When the hole H is detected by the optical sensor 66, a waveform of ultrasound output from the ultrasonic sensor 60 becomes invalid before or after the hole H passes the search range of the ultrasonic sensor 60. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sheet material conveying apparatus that detects double feeding of sheet materials using an ultrasonic sensor, and an image forming apparatus including the sheet material conveying apparatus.

  Conventionally, in an image forming apparatus such as an electrophotographic system or an ink jet system, an ultrasonic sensor is used to detect double feeding in which a plurality of sheet materials are conveyed while being overlapped (see, for example, Patent Documents 1 and 2). ). In the double feed detection method using an ultrasonic sensor, a transmitter and a receiver are opposed to each other across a sheet material conveyance path, and ultrasonic waves are transmitted from the transmitter to the receiver. The ultrasonic wave receiving means receives the ultrasonic wave attenuated when passing through the sheet material, and outputs the waveform of the received ultrasonic wave. Then, the ultrasonic wave waveform output from the receiving means is compared with the threshold value for when one sheet is conveyed and when it is double-fed to determine whether or not the sheet material is being double-fed. This double feed detection method can detect double feed in a non-contact manner with respect to the sheet material, so that the skew of the sheet material can be suppressed and the double feed can be detected without being influenced by the color of the sheet material.

  However, since the ultrasonic waves are diffracted at the edge portion of the sheet material, the intensity of the ultrasonic waves received by the receiver is lowered, and double feeding may be erroneously detected. In particular, when a hole formed in the sheet material passes through the search range of the ultrasonic sensor, erroneous detection of double feeding frequently occurs.

Further, since the ultrasonic sensor is installed in the vicinity of the sheet material conveyance path, there is a problem in that paper dust is likely to adhere to the transmission surface and the reception surface, and the double feed detection accuracy is lowered.
JP 200287641 A JP 2005-15124 A

  The present invention has been made in consideration of the above-described facts, and prevents erroneous detection of double feeding that occurs when a sheet material with holes formed therein is conveyed. In addition, paper dust is prevented from adhering to the transmission surface and reception surface of the ultrasonic sensor, and the double feed detection accuracy is improved.

  The sheet material conveying apparatus according to claim 1, the conveying means for conveying the sheet material, the transmitting means for allowing the ultrasonic wave to pass through the sheet material conveyed by the conveying means, and the transmission with the conveying path of the sheet material interposed therebetween. A receiving means for receiving the ultrasonic wave transmitted from the transmitting means and outputting the waveform of the received ultrasonic wave, and an ultrasonic sensor output from the receiving means. And a multi-feed detection unit that determines multi-feed of the sheet material based on the waveform, and is freed by the sheet material conveyed by the conveyance unit and passes through a search range of the ultrasonic sensor. A hole detecting means for detecting a hole, and a waveform for invalidating an ultrasonic waveform output from the receiving means before and after the hole detected by the hole detecting means passes through a search range of the ultrasonic sensor. Characterized in that it has a control means.

  In the sheet material conveying apparatus according to the first aspect, the ultrasonic sensor includes a transmitting unit and a receiving unit facing each other across the sheet material conveying path. The transmitting means transmits ultrasonic waves to pass the sheet material conveyed by the conveying means. The receiving means receives the ultrasonic wave transmitted from the transmitting means and passed through the sheet material, and outputs the waveform of the received ultrasonic wave. Then, the double feed detecting means determines the double feed of the sheet material based on the ultrasonic waveform output from the receiving means.

  Here, when the hole formed in the sheet material passes through the search range of the ultrasonic sensor, it is detected by the hole detecting means. Then, before and after the hole detected by the hole detecting means passes through the search range of the ultrasonic sensor, the waveform of the ultrasonic wave output from the receiving means is invalidated by the first control means.

  That is, the noise of the ultrasonic sensor due to the ultrasonic wave being diffracted at the position of the hole formed in the sheet material is removed. Accordingly, it is possible to prevent erroneous detection of double feeding that occurs when a sheet material with holes is conveyed.

  A sheet material conveying apparatus according to a second aspect is the sheet material conveying apparatus according to the first aspect, wherein the sheet material conveying apparatus is disposed upstream of the search range of the ultrasonic sensor in the conveying direction and detects the sheet material. Sheet material detection means, second sheet material detection means arranged on the downstream side of the search range of the ultrasonic sensor in the conveying direction, for detecting the sheet material, the first sheet material detection means, and the second sheet material detection And a second control unit that validates the waveform of the ultrasonic wave output from the receiving unit only while the sheet material is detected by both of the units.

  The sheet material conveying apparatus according to claim 2, wherein the first sheet material detecting means disposed on the upstream side in the conveying direction of the search range of the ultrasonic sensor, and disposed on the downstream side in the conveying direction of the search range of the ultrasonic sensor. The second control means validates the waveform output from the receiving means only while the sheet material is detected by both of the second sheet material detecting means.

  Here, while the sheet material is detected by both the first sheet material detection unit and the second sheet material detection unit, the leading edge and the trailing edge of the sheet material exist in the search range of the ultrasonic sensor. Therefore, it is possible to prevent erroneous detection of double feeding of the sheet material due to the disturbance of the output of the ultrasonic sensor that is generated by diffracting the ultrasonic wave at the leading edge and the trailing edge of the sheet material.

  Further, since it is easy to determine whether or not the sheet material passes the search range of the ultrasonic sensor, it is easy to select the output value of the ultrasonic sensor, so that the control can be simplified.

  The sheet material conveying apparatus according to claim 3, the conveying means for conveying the sheet material, the transmitting means for allowing the ultrasonic wave to pass through the sheet material conveyed by the conveying means, and the transmission with the conveying path of the sheet material interposed therebetween. A receiving means for receiving the ultrasonic wave transmitted from the transmitting means and outputting the waveform of the received ultrasonic wave, and an ultrasonic sensor output from the receiving means. And a multi-feed detection unit that determines multi-feed of the sheet material based on the waveform, and is freed by the sheet material conveyed by the conveyance unit and passes through a search range of the ultrasonic sensor. A hole detecting means for detecting a hole; a sensor moving means for moving the ultrasonic sensor in a direction crossing a conveying direction of the sheet material; and the sensor movement when the hole is detected by the hole detecting means. Actuating the stage, and having a second control means for retracting the ultrasonic sensor from the passing position of the hole.

  In the sheet material conveying apparatus according to claim 3, when the hole that is vacated in the sheet material and passes through the search range of the ultrasonic sensor is detected by the hole detection unit, the sensor moving unit is operated by the second control unit, The ultrasonic sensor is moved in a direction crossing the sheet material conveyance direction and retracted from the hole passing position.

  Accordingly, it is possible to prevent erroneous detection of double feeding of the sheet material that occurs when the hole formed in the sheet material passes through the search range of the ultrasonic sensor.

  The sheet material conveying apparatus according to claim 4, the conveying means for conveying the sheet material, the transmitting means for passing the ultrasonic wave through the sheet material conveyed by the conveying means, and the transmission with the conveying path of the sheet material interposed therebetween. A receiving means for receiving the ultrasonic wave transmitted from the transmitting means and outputting the waveform of the received ultrasonic wave, and an ultrasonic sensor output from the receiving means. And a multi-feed detection unit that determines multi-feed of the sheet material based on the waveform, and is freed by the sheet material conveyed by the conveyance unit and passes through a search range of the ultrasonic sensor. When the hole is detected by the hole detecting means for detecting the hole, the sheet material moving means for moving the sheet material conveyed by the conveying means in a direction crossing the conveying direction, and the hole detecting means. It actuates the serial sheet material moving means, and having a third control means for retracting the search range of the ultrasonic sensor passing position of the hole.

  In the sheet material conveying apparatus according to claim 4, when the hole detecting unit detects a hole that is formed in the sheet material and passes through the search range of the ultrasonic sensor, the third control unit operates the sheet material moving unit. The passage position of the hole is moved in a direction intersecting with the sheet material conveyance direction, and is retracted from the search range of the ultrasonic sensor.

  Accordingly, it is possible to prevent erroneous detection of double feeding of the sheet material that occurs when the hole formed in the sheet material passes through the search range of the ultrasonic sensor.

  The sheet material conveying device according to claim 5 is the sheet material conveying device according to any one of claims 1 to 4, wherein a search range of the hole detecting means is set to be a search range of the ultrasonic sensor. Is also widened in a direction orthogonal to the sheet material conveying direction.

  In the sheet material conveying apparatus according to the fifth aspect, the search range of the hole detecting means is wider in the direction perpendicular to the sheet material conveying direction than the search range of the ultrasonic sensor. Accordingly, a hole that slides into the search range of the ultrasonic sensor immediately before the search range of the ultrasonic sensor due to the blur of the sheet material can be detected by the hole detection means. Accordingly, it is possible to accurately detect the double feeding of the sheet material even when the sheet material is not stabilized and the sheet material is shaken or skewed.

  The sheet material conveying apparatus according to claim 6 is the sheet material conveying apparatus according to any one of claims 1 to 5, wherein the hole detecting means is a light emitting means and a light beam emitted from the light emitting means. And a light receiving means for receiving the light, and the light sensor is attached to a support member that supports the ultrasonic sensor, and the light emitting means and the light receiving means are used to align the light emitting means. Positioning with the receiving means is performed.

  In the sheet material conveying apparatus according to claim 6, the optical sensor configured by the light emitting means and the light receiving means is attached to a support member that supports the ultrasonic sensor, and the alignment of the transmitting means and the receiving means is performed, This is performed using alignment between the light emitting means and the light receiving means. For this reason, it is possible to precisely align the ultrasonic sensor by reducing the light diameter of the optical sensor.

  The sheet material conveying apparatus according to claim 7 is the sheet material conveying apparatus according to any one of claims 1 to 6, wherein the transmitting means is the receiving means, and the receiving means is the transmitting means. It has a transmission / reception selection means for switching.

  In the sheet material conveying apparatus according to the seventh aspect, the transmission / reception selection unit switches the transmission unit to the reception unit and the reception unit to the transmission unit. That is, the two elements of the ultrasonic sensor are alternately vibrated to prevent paper dust and dust from accumulating on the two elements. Thereby, the detection accuracy of double feeding of the sheet material is improved.

  The sheet material conveying apparatus according to claim 8 is the sheet material conveying apparatus according to any one of claims 1 to 7, wherein the sheet material conveying apparatus is configured to open and close the transmitting surface of the transmitting means and the receiving surface of the receiving means. And an opening / closing control means for causing the opening / closing means to close the transmitting surface and the receiving surface except during the search of the ultrasonic sensor.

  In the sheet material conveying apparatus according to an eighth aspect of the invention, the opening / closing control means causes the opening / closing means to close the transmitting surface of the transmitting means and the receiving surface of the receiving means except during the search of the ultrasonic sensor. As a result, the amount of paper dust or dust attached to the transmission surface or reception surface can be minimized.

  The sheet material conveying apparatus according to claim 9 is the sheet material conveying apparatus according to any one of claims 1 to 8, wherein the transmitting surface of the transmitting means or the receiving surface of the receiving means is in a horizontal direction. Sensor rotation means for rotating around an extending axis is provided.

  In the sheet material conveying apparatus according to the ninth aspect, the transmitting surface of the transmitting unit or the receiving surface of the receiving unit is rotated about the axis extending in the horizontal direction by the sensor rotating unit. As a result, it is possible to increase the inclination angle of the transmission surface or the reception surface with respect to the horizontal direction and to drop paper dust or dust attached to the transmission surface or the reception surface.

  An image forming apparatus according to a tenth aspect is the sheet material conveying apparatus according to any one of the first to ninth aspects, and an image forming unit that forms an image on the sheet material conveyed by the sheet material conveying apparatus. It is characterized by having.

  In the image forming apparatus according to the tenth aspect, even when a hole is formed in the sheet material which is conveyed by the conveying unit and forms an image, double feeding is accurately detected, so that the image formation is interrupted unnecessarily. There is nothing to do.

  Since the present invention has the above-described configuration, it is possible to prevent erroneous detection of double feed that occurs when a sheet material with holes is conveyed. Further, it is possible to suppress paper dust from adhering to the transmission surface and the reception surface of the ultrasonic sensor, and it is possible to improve double feed detection accuracy.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the image forming apparatus 1 is a color laser printer using an electrophotographic system, and a display unit 62 such as a liquid crystal display panel is provided on the upper surface, and preprinted paper P is loaded therein. A sheet feeding cassette 20, an image forming unit 14 for forming a desired image on the sheet material P, a fixing device 12 for fixing an image formed on the sheet material P, and a sheet material P. And a control unit 80 that controls the operation of the image forming apparatus 1 as a whole.

  In this image forming apparatus 1, first, a toner image is formed on the photoreceptor belt 16 by the image forming unit 14, and this toner image is transported from the paper feed cassette 20 to the transfer unit 22 by the transport roll 18. Is transferred to. The sheet material P onto which the toner image has been transferred is pressurized and heated by the fixing device 12 on the downstream side in the transport direction of the transfer unit 22 to fix the toner image on the sheet material P, and is discharged to the stacker 26 by the paper discharge roll 24. The paper is ejected. When images are formed on both the front and back sides of the sheet material P, the conveyance path on the downstream side in the conveyance direction of the fixing device 12 is switched, and the sheet material P with the toner image fixed on the surface reverses the front and back sides. Is transported to the rear surface transport path 28. Then, the sheet material P whose front and back sides are reversed is transported to the upstream side in the transport direction of the transfer unit 22 by the transport belt 29 and is transported again to the transfer unit 22 by the transport roll 18 to form a toner image on the back surface from the photosensitive belt 16. Transcribed. Then, the sheet material P passes through the fixing device 12, the toner image is fixed on the back surface, and is discharged to the stacker 26 by the discharge roll 24.

  The image forming unit 14 is provided with a photosensitive belt 16. The photosensitive belt 16 is rotated by two rolls 34 arranged in a horizontal direction of two rolls 31 and 32 and rolls 31 and 32 arranged along a conveyance path 30 extending in the vertical direction. The flat surfaces 16A, 16B, 16C, and 16D are formed vertically and horizontally. The upper and lower flat surfaces 16A and 16B are longer than the left and right flat surfaces 16C and 16D.

  A plurality of print engines 36 that form toner images of different colors such as red and black on the surface of the photoreceptor belt 16 are arranged along the lower flat surface 16B. Each print engine 36 includes a charger 37, an exposure head 38, and a developer 39 that are sequentially arranged in the rotation direction of the photosensitive belt 16 (the direction of arrow A in the figure). The charger 37 uniformly charges the photosensitive belt 16 with a charging corotron, a charging roll, or the like. Further, the exposure head 38 exposes the charged surface of the photosensitive belt 16 with an LED array, an optical scanning device (Raster Optical Scanner), or the like to form an electrostatic latent image on the photosensitive belt 16 based on image data. . The developing device 39 contains a one-component developer made of toner or a two-component developer made of toner or carrier, and transports the developer to the developing roll 39A while stirring the developer in the developing device 39. The developing device 39 applies a developing bias to the developing roll 39A, and moves the toner from the developing roll 39A onto the electrostatic latent image on the photosensitive belt 16. As a result, the electrostatic latent image on the photoreceptor belt 16 is visualized with toner.

  The transfer corotron 42 is disposed facing the flat surface 16D across the transport path. The transfer corotron 42 discharges toward the back surface of the sheet material P, gives a charge having a polarity opposite to the toner charge to the back surface of the sheet material P without contact, and transfers the toner image on the photosensitive belt 16 to the sheet material P. Transcript.

  Further, a cleaning mechanism 44 (cleaner blade is shown) such as a cleaner blade and a cleaner roll is disposed facing the flat surface 16C of the photosensitive belt 16. The cleaning mechanism 44 removes untransferred residual toner remaining on the photosensitive belt 16 without being transferred to the sheet material P by the transfer unit 22 from the photosensitive belt 16.

  The fixing device 12 disposed on the downstream side in the transport direction of the transfer unit 22 is in contact with the transfer surface of the sheet material P and rotates, and the sheet material P is pressed against the heat roll 46 between the sheet material P and the sheet. A pressure roll 48 that rotates in contact with the back surface of the material P is provided, and a fixing nip N is formed by the heat roll 46 and the pressure roll 48. A heater lamp 50 such as a halogen lamp is disposed inside the heat roll 46, and the surface of the heat roll 46 is heated. Therefore, when the sheet material P to which the toner image is transferred passes through the fixing nip N, the sheet material P is heated and pressurized, and the toner on the sheet material is melted and fixed to the sheet material P.

  Here, the fixing device 12 is provided with a release agent supply device 13. The release agent supply device 13 includes a donor roll 52 in contact with the surface of the heat roll 46, a tank 54 storing a release agent such as silicon oil, a donor roll 52, and a release agent in the tank 54 that absorbs sponge and the like. A metering roll 56 that is in contact with the body is provided.

  A metering blade (not shown) is in contact with the surface of the metering roll 56. The metalling blade contacts the surface of the metalling roll 56 with a predetermined pressure, and regulates (measures) the release agent on the surface of the metalling roll 56 to a predetermined thickness with micron order accuracy.

  A release agent having a predetermined thickness on the surface of the metalling roll 56 is conveyed to the surface of the heat roll 46 by the donor roll 52, and a layer of the release agent having a predetermined thickness is formed on the surface of the heat roll 46. Is formed. This improves the releasability of the toner on the sheet material P from the surface of the heat roll 46 in the fixing nip N, so that fixing failure and toner fixing offset can be prevented.

  Further, a purge tray 27 is disposed on the downstream side of the fixing device 12 in the conveyance direction, and some trouble occurs during the conveyance, and an appropriate printing process cannot be performed. Ejected and loaded.

  An ultrasonic sensor 60 is disposed in the horizontal conveyance path upstream of the transfer unit 22 in the conveyance direction. The ultrasonic sensor 60 is composed of a transmitter 60A and a receiver 60B that face each other across the conveyance path of the sheet material P. The transmitter 60A transmits the sheet material P conveyed by transmitting ultrasonic waves. The receiver 60B receives the ultrasonic wave transmitted from the transmitter 60A and attenuated through the sheet material P, and outputs the waveform of the received ultrasonic wave as a voltage waveform.

  As shown in FIG. 2, the output of the receiver 60 </ b> B is connected to the double feed determination unit 64, and the voltage waveform output from the receiver 60 </ b> B is input to the double feed determination unit 64. The double feed determination unit 64 stores in advance the voltage value when there is no double feed (one sheet) as a reference value, and the double feed determination unit 64 compares the input voltage value with the reference value. When the value is lower than the reference value range, that is, when the attenuation amount of the waveform of the ultrasonic wave received by the receiver 60B is larger than that when one sheet material is used, it is determined that the sheet material P is double-fed. Conversely, the double feed determination unit 64 determines that there is no double feed of the sheet material P when the input voltage value is greater than or equal to the reference value range.

  Further, as shown in FIGS. 3A and 3B, the optical sensor 66 is disposed on the upstream side in the transport direction of the ultrasonic sensor 60. The optical sensor 66 includes a light emitter 66A and a light receiver 66B that face each other across the conveyance path of the sheet material P. The light emitter 66A emits a light beam toward the light receiver 66B. When the light receiver 66B receives the light beam, it outputs a detection signal as a voltage. As shown in FIG. 2, the output of the light receiver 66 </ b> B is connected to the control unit 80, and the voltage output from the light receiver 66 </ b> B is input to the control unit 80.

  The optical sensor 66 and the ultrasonic sensor 60 are arranged side by side on the same straight line in the conveying direction. When the hole H formed in the sheet material P passes through the search range of the ultrasonic sensor 60, the hole H It passes the search range of the optical sensor 66 before. At this time, the light emitted from the light emitter 66A passes through the hole H and is received by the light receiver 66B, and a detection signal is output from the light receiver 66B to the control unit 80.

  Further, the display unit 62, the image forming unit 14, the fixing device 12, and the sheet material conveying device 10 are connected to the control unit 80. The control unit 80 sends control signals to these units to control the overall operation of the image forming apparatus 1.

  Here, the double feed detection method of the sheet material P in the double feed determination unit 64 will be described with reference to the flowchart of FIG.

  First, when the control unit 80 receives a print job, a processing routine is started and the process proceeds to step 100. In step 100, the operations of the optical sensor 66 and the ultrasonic sensor 60 are started, and the process proceeds to step 101. In step 101, it is determined whether or not the voltage value output from the ultrasonic sensor 60 is greater than or equal to the range of the reference voltage value, that is, whether or not the sheet material P is being double fed. Then, the process proceeds to step 102. In step 102, the sheet material P being conveyed is discharged to the purge tray 27 by the sheet material conveying device 10, and the sheet material P is stopped from being fed from the sheet cassette 20, and printing is interrupted on the display unit 62. A warning display is displayed to warn you that In step 103, the negative determination is repeated until a print instruction for the remaining print is input. If the determination is affirmative, the process proceeds to step 101, and the subsequent print is executed.

  On the other hand, in step 104, it is determined whether or not a voltage is output from the optical sensor 66, that is, whether or not the hole H passing through the search range of the ultrasonic sensor 60 is detected by the optical sensor 66. If NO, the process proceeds to step 106. In step 105, the timing at which the hole H passes the search range of the ultrasonic sensor 60 is calculated from the distance between the optical sensor 66 and the ultrasonic sensor 60 and the conveyance speed of the sheet material P, and the hole H is searched by the ultrasonic sensor 60. The voltage waveform output from the ultrasonic sensor 60 during the predetermined time immediately before and after passing through the range is invalidated. Then, the process returns to step 101, and the presence / absence of double feeding of the sheet material P is determined.

  That is, when the hole H passes through the search range of the ultrasonic sensor 60, the disturbance (noise) of the output of the ultrasonic sensor 60 generated by the ultrasonic wave being diffracted at the periphery of the hole H is removed, and the sheet is removed. The presence / absence of double feeding of the material P is determined. Thereby, it is possible to prevent erroneous detection of double feeding of the sheet material P in which the holes H are formed.

  On the other hand, in step 106, the negative determination is repeated until the print job is completed, and the process returns to step 101. If the determination is affirmative, the processing routine is ended.

  Next, a second embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted.

  As shown in FIGS. 5A and 5B, in the sheet material conveyance device 70, the first optical sensor 72 and the second optical sensor 74 are disposed on the upstream side and the downstream side, respectively, in the conveyance direction of the ultrasonic sensor 60. ing. The first optical sensor 72 includes a light emitter 72A and a light receiver 72B that are opposed to each other with the conveyance path of the sheet material P interposed therebetween, and the second optical sensor 74 is a light emitter that is opposed to each other across the conveyance path of the sheet material P. 74A and a light receiver 74B. As shown in FIG. 6, the outputs of the light receivers 72B and 74B are connected to the control unit 90, and the light receivers 72B and 74B output a voltage to the control unit 90 when receiving the light beam.

  Further, as shown in FIG. 5B, the optical sensors 72 and 74 and the ultrasonic sensor 60 are arranged side by side on the same straight line in the conveying direction, and the hole H formed in the sheet material P has an ultrasonic wave. When passing through the search range of the sensor 60, the hole H passes through the search range of the optical sensor 72 before that. At this time, the light emitted from the light emitter 72A passes through the hole H and is received by the light receiver 72B, and a voltage is output from the light receiver 72B to the control unit 90.

  Before the sheet material P is conveyed to the search range of the optical sensors 72 and 74, the light beams emitted from the light emitters 72A and 74A are received by the light receivers 72B and 74B, respectively, and the sheet material P is received by the optical sensor 72. , 74 is transported to the search range, the light beam transmitted from the light emitters 72A, 74A is blocked by the sheet material P, and the light receivers 72B, 74B do not receive the light beam.

  Here, the double feed detection method of the sheet material P in the double feed determination unit 64 will be described with reference to the flowchart of FIG.

  First, when the control unit 90 receives a print job, a processing routine is started and the process proceeds to step 200. In step 200, the operations of the first optical sensor 72, the second optical sensor 74, and the ultrasonic sensor 60 are started, and the process proceeds to step 201. In step 201, until the voltage output from both the first optical sensor 72 and the second optical sensor 74 is interrupted, that is, until the sheet material P is detected by both the first optical sensor 72 and the second optical sensor 74. If the negative determination is repeated and the determination is affirmative, the routine proceeds to step 202.

  In step 202, it is determined whether or not the voltage value output from the ultrasonic sensor 60 is equal to or greater than the range of the reference voltage value, that is, whether or not the sheet material P is double fed. Then, the process proceeds to step 203. In step 203, the sheet material P being conveyed is discharged to the purge tray 27 by the sheet material conveyance device 70, and the sheet material P is stopped from being fed from the sheet feeding cassette 20, and printing is interrupted on the display unit 62. A warning display is displayed to warn you that In step 204, the negative determination is repeated until a print instruction for the remaining prints is input. If the determination is affirmative, the process proceeds to step 201 to continue printing.

  On the other hand, in step 205, it is determined whether or not a voltage is output from the optical sensor 66, that is, whether or not the hole H that passes through the search range of the ultrasonic sensor 60 is detected by the first optical sensor 72. If yes, the process proceeds to step 206; In step 206, the timing at which the hole H passes the search range of the ultrasonic sensor 60 is calculated from the distance between the optical sensor 66 and the ultrasonic sensor 60 and the conveyance speed of the sheet material P, and the hole H is searched by the ultrasonic sensor 60. The voltage waveform output from the ultrasonic sensor 60 during the predetermined time immediately before and after passing through the range is invalidated. Then, the process returns to step 201.

  On the other hand, in step 207, negative determination is repeated until the print job is completed, the process returns to step 101, and if affirmed, the processing routine is ended.

  Here, while the output voltage from both the first optical sensor 72 and the second optical sensor 74 is interrupted, that is, the sheet material P is detected by both the first optical sensor 72 and the second optical sensor 74. In the meantime, since the leading edge and the trailing edge of the sheet material P do not exist in the search range of the ultrasonic sensor 60, the ultrasonic wave is diffracted by the leading edge and the trailing edge of the sheet material P. It is possible to prevent erroneous detection of double feeding of the sheet material P due to the disturbance in the output of the ultrasonic sensor 60 that is generated.

  In addition, it can be easily determined whether or not the sheet material P has passed the search range of the ultrasonic sensor 60, and the output value of the ultrasonic sensor 60 can be easily selected, so that the control becomes simple.

  Next, a third embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st, 2nd embodiment, and description is abbreviate | omitted.

  As shown in FIG. 8, in the sheet material conveying apparatus 100, the line sensor 76 is disposed on the upstream side in the conveying direction of the search range of the ultrasonic sensor 60. The line sensor 76 includes a line-shaped light emitter 76A in which light-emitting elements are arranged in a direction orthogonal to the transport direction, and a line-shaped light receiver 76B in which light-receiving elements are arranged in a direction orthogonal to the transport direction. ing. The light emitter 76A and the light receiver 76B face each other across the conveyance path of the sheet material P, and the light emitted from the light emitter 76A is received by the light receiver 76B.

  Here, the search range of the line sensor 76 is expanded in a direction perpendicular to the conveyance direction more than the search range of the ultrasonic sensor 60, and the ultrasonic sensor immediately before the search range of the ultrasonic sensor due to the blurring of the sheet material P. The hole H that slides into the 60 search range is also detected by the line sensor 76. Accordingly, even when the sheet material P is shaken or skewed without being stably conveyed, it is possible to accurately detect double feeding of the sheet material P.

  Next, a fourth embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st thru | or 3rd embodiment, and description is abbreviate | omitted.

  As shown in FIGS. 9A and 9B, in the sheet material conveying apparatus 110, the transmitter 60 </ b> A of the ultrasonic sensor 60, the light emitter 72 </ b> A of the first optical sensor 72, and the light emitter 74 </ b> A of the second optical sensor 74. Are attached to the same support member 78A in alignment with each other. Further, the receiver 60B of the ultrasonic sensor 60, the light receiver 72B of the first light sensor 72, and the light receiver 74B of the second light sensor 74 are attached to the same support member 78B in alignment with each other.

  Here, the directions of the light beams of the first optical sensor 72 and the second optical sensor 74 and the ultrasonic waves of the ultrasonic sensor are substantially parallel, and the light emitter 72A and the light receiver 72B of the first optical sensor 72 are aligned. The positioning of the transmitter 60A and the receiver 60B of the ultrasonic sensor 60 is performed by precisely aligning the light emitter 74A and the light receiver 74B of the second optical sensor 74 by narrowing the light diameter of the light beam. Is going.

  Next, a fifth embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st thru | or 4th embodiment, and description is abbreviate | omitted.

  As shown in FIGS. 10A and 10B, in the sheet material conveying apparatus 120, the transmitter 60A and the receiver 60B of the ultrasonic sensor 60 are supported by the support members 116A and 116B, respectively. The support members 116A and 116B are respectively attached to slide rails 118A and 118B extending in a direction orthogonal to the conveyance direction, and the transmitter 60A and the receiver 60B are movable in the direction orthogonal to the conveyance direction. .

  In addition, racks 122A and 122B extending along a direction orthogonal to the transport direction are formed on the support members 116A and 116B, respectively. The racks 122A and 122B are engaged with gears 126A and 126B attached to the rotation shafts of the motors 124A and 124B, respectively, and the transmitters 60A and the receiver 60B are moved in the conveying direction by driving the motors 124A and 124B, respectively. It is moved in the orthogonal direction.

  Here, the motors 124A and 124B are controlled by a motor driver 128. When the hole H is detected by the optical sensor 66, the motor driver 128 drives the motors 124A and 124B and moves the transmitter 66A and the receiver 66B to face each other, thereby setting the search range of the ultrasonic sensor 66A. Retreat from the H passing position.

  Accordingly, it is possible to prevent erroneous detection of double feeding of the sheet material P that occurs when the hole H formed in the sheet material P passes through the search range of the ultrasonic sensor 60.

  Next, a sixth embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st thru | or 5th embodiment, and description is abbreviate | omitted.

  As shown in FIGS. 11A and 11B, in the sheet material conveying apparatus 130, a sheet material moving mechanism 132 that moves the sheet material P in a direction orthogonal to the conveying direction is provided. This sheet material moving mechanism 132 supports a roll 134, which is disposed below the conveyance path of the sheet material P and is inclined with respect to the conveyance direction, and a roll 134 rotatably. A U-shaped frame 136 that is movably supported, an eccentric cam 138 that contacts the lower surface of the frame 136, a motor 142 having the eccentric cam 138 attached to the rotation shaft, and a direction orthogonal to the conveying direction of the sheet material P And a side guide 146 extending along the transport direction.

  As shown in FIG. 11A, when the roll 134 is raised to the uppermost position by the eccentric cam 138, the roll 134 comes into contact with the lower surface of the sheet material P. When the roll 134 comes into contact with the lower surface of the sheet material P, as shown in FIG. 11B, the sheet material P skews along the roll 134 inclined with respect to the conveyance direction, and the conveyance direction as shown by the chain line. It slides to one end side in the direction orthogonal to the side guide 146.

  The motor 142 is controlled by the motor driver 144. When the hole H is detected by the optical sensor 66, the motor driver 144 drives the motor 142, raises the roll 134 to the uppermost position, contacts the lower surface of the sheet material P, and makes the sheet material P orthogonal to the conveyance direction. Move to one end in the direction of As a result, the hole H is retracted from the search range of the ultrasonic sensor 66 </ b> A, and therefore the double feed of the sheet material P that occurs when the hole H formed in the sheet material P passes through the search range of the ultrasonic sensor 60. False detection can be prevented.

  Next, a seventh embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st thru | or 6th embodiment, and description is abbreviate | omitted.

  As shown in FIG. 12, in the sheet material conveying apparatus 140, the ultrasonic sensor 82 includes a transmitting / receiving device 82A and a receiving / transmitting device 82B facing each other across the conveying path of the sheet material P. The transmitter / receiver 82A and the receiver / transmitter 82B are configured by a common piezoelectric element, and the role of transmission and the role of reception are switched by the selector 84.

The selector 84 switches the transmitter of the ultrasonic sensor 82 to the receiver and the receiver to the transmitter and vibrates the two elements of the ultrasonic sensor 82 alternately for each predetermined number of printed sheets. Prevent paper dust and dust from accumulating on top. This improves the detection accuracy of the double feed of the sheet material P. Next, an eighth embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st thru | or 7th Embodiment, and description is abbreviate | omitted.

  As shown in FIG. 13, in the sheet material conveyance device 150, the conveyance guide 86 </ b> A and the conveyance guide 86 </ b> B face each other with the conveyance path of the sheet material P interposed therebetween. The transmitter 60A and the receiver 60B of the ultrasonic sensor 60 are opposed to each other with the conveyance guides 86A and 86B interposed therebetween. The conveyance guides 86A and 86B have openings 88A and 88B through which the ultrasonic waves transmitted from the transmitter 60A pass, respectively.

  Covers 92A and 92B for opening and closing the openings 88A and 88B are slidably attached to the transport guides 86A and 86B, respectively. Racks 94A and 94B are formed on the covers 92A and 92B, respectively, and 96A attached to the rotating shaft of the motor 96 is engaged with the racks 94A and 94B.

  A motor driver 98 that controls the motor 96 is also provided. As shown in FIG. 14A, the motor driver 98 drives the motor 96 immediately before the sheet material P passes through the search range of the ultrasonic sensor 60 to retract the covers 92A and 92B from the openings 88A and 88B. The openings 88A and 88B are opened. Then, as shown in FIG. 14B, immediately after the sheet material P passes through the search range of the ultrasonic sensor 60, the motor 96 is driven to slide the covers 92A and 92B to a position overlapping the openings 88A and 88B. The openings 88A and 88B are closed.

  In this way, except when the sheet material P passes through the search range of the ultrasonic sensor 60, the paper adhering to the ultrasonic sensor 60 is covered by covering the transmitting surface and the receiving surface of the ultrasonic sensor 60 with the covers 92A and 92B. The amount of dust and dust can be minimized, and the accuracy of detecting the double feed of the sheet material P can be improved.

  Next, a ninth embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st thru | or 8th Embodiment, and description is abbreviate | omitted.

  As shown in FIG. 15, in the sheet material conveying apparatus 160, the transmitter 60A of the ultrasonic sensor 60 is supported by the support member 102A, and the receiver 60B of the ultrasonic sensor 60 is supported by the support member 102B. Covers 104A and 104B that open and close the transmitting surface of the transmitter 60A and the receiving surface of the receiver 60 are rotatably supported by the supporting members 102A and 102B via hinges 106A and 106B, respectively.

  Torsion coil springs (not shown) are attached to the hinge portions 106A and 106B, and the covers 104A and 104B are urged by the torsion coil springs in a direction to open the transmission surface and the reception surface. Further, solenoids 108A and 108B are attached to the support members 102A and 102B, respectively. As shown in FIG. 15 (A), the solenoids 108A and 108B are made in a non-excited state by projecting the movable iron cores 112A and 112B outward to twist the covers 104A and 104B against the urging force of the coil spring. Rotate to close the transmitting and receiving surfaces. Further, as shown in FIG. 15B, when the solenoids 108A and 108B are energized, the movable iron cores 112A and 112B are retracted inward to rotate the covers 104A and 104B by the biasing force of the coil spring. , The transmission surface and the reception surface are opened.

  Excitation and de-excitation of the solenoids 108A and 108B are controlled by the open / close control unit 114, and the open / close control unit 114 allows the sheet material P to pass through the search range of the ultrasonic sensor 60 as shown in FIG. The solenoids 108A and 108B are de-energized except when the operation is performed, and the solenoids 108A and 108B are excited only when the sheet material P passes through the search range of the ultrasonic sensor 60 as shown in FIG.

  As a result, the amount of paper dust and dust adhering to the ultrasonic sensor 60 can be suppressed to a minimum, and the accuracy of detecting the double feed of the sheet material P can be improved.

  Next, a tenth embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st thru | or 9th embodiment, and description is abbreviate | omitted.

  As shown in FIG. 16, in the sheet material conveyance device 170, the receiver 60 </ b> B of the ultrasonic sensor 60 can be rotated by a sensor rotation mechanism 148. The sensor rotating mechanism 148 includes a rotating member 152 that supports the receiver 60B, a rotating shaft 154 that extends horizontally from the rotating member 152, and a supporting member that rotatably supports the rotating member 152 via the rotating shaft 154. 156, a gear 158 attached to the rotation shaft 154, and a motor 164 having a gear 162 meshing with the gear 158 attached to the rotation shaft.

  That is, when the motor 164 is driven, the receiving surface of the receiver 60B is rotated around the rotation shaft 154. As a result, the inclination angle of the receiving surface of the receiver 60B with respect to the horizontal direction is increased, and paper dust and dust adhering to the receiving surface of the receiver 60B are dropped.

  In this embodiment, since the receiving surface of the receiver 60B is upward, the receiver 60B is rotated. However, when the transmitting surface of the transmitter 60B is upward, the transmitter 60A may be rotated.

  In the first to tenth embodiments, the sheet material conveying apparatus of the present invention has been described by taking an electrophotographic image forming apparatus as an example. However, the present invention is not limited to this, and an ink jet image forming apparatus or image The sheet material conveying apparatus of the present invention can also be applied to an inspection apparatus or a post-processing apparatus for performing post-processing such as booklet creation, stapling, or folding on a sheet material.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an exemplary embodiment. 1 is a block diagram illustrating a configuration of an electric system of an image forming apparatus according to a first embodiment. (A) which shows the sheet material conveying apparatus of 1st Embodiment is a side view, (B) is a top view. It is a flowchart for demonstrating the double feed detection method of the sheet material conveying apparatus of 1st Embodiment. (A) which shows the sheet material conveying apparatus of 2nd Embodiment is a side view, (B) is a top view. It is a block diagram which shows the structure of the electric system of the image forming apparatus of 2nd Embodiment. It is a flowchart for demonstrating the double feed detection method of the sheet material conveying apparatus of 2nd Embodiment. It is a top view which shows the sheet material conveying apparatus of 3rd Embodiment. (A) which shows the sheet material conveying apparatus of 4th Embodiment is a side view, (B) is a top view. It is a side view which shows the sheet material conveying apparatus of 5th Embodiment. (A) which shows the sheet material conveying apparatus of 6th Embodiment is a side view, (B) is a top view. (A) which shows the sheet material conveying apparatus of 7th Embodiment is a side view, (B) is a top view. It is a perspective view which shows the sheet material conveying apparatus of 8th Embodiment. (A), (B) is sectional drawing which shows the sheet material conveying apparatus of 8th Embodiment. (A), (B) is sectional drawing which shows the sheet material conveying apparatus of 9th Embodiment. It is a side view which shows the sheet material conveying apparatus of 10th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Sheet material conveying apparatus 14 Image forming part (image forming means)
18 Transport roll (transport means)
60 Ultrasonic sensor 60A Transmitter (transmitting means)
60B receiver (reception means)
64 Double feed determination unit (Double feed detection means)
66 Optical sensor (hole detection means)
70 Sheet Material Conveying Device 72 First Optical Sensor (Hole Detection Unit, First Sheet Material Detection Unit)
74 Second optical sensor (second sheet material detecting means)
76 Line sensor (hole detection means)
78A Support member 78B Support member 80 Control unit (first control means)
82 Ultrasonic sensor 82A Transmission / reception means (transmission means, reception means)
82B Reception / transmission means (reception means, transmission means)
84 selector (transmission / reception selection means)
86A Conveying Guide 86B Conveying Guide 88A Opening 88B Opening 90 Control Unit (first control means, second control means)
92A Cover (opening / closing means)
92B Cover (opening / closing means)
96 Motor (opening / closing means)
98 Motor driver (open / close control means)
100 Sheet material conveying device 104A Cover (opening / closing means)
104B Cover (opening / closing means)
108A Solenoid (open / close means)
108B Solenoid (open / close means)
110 Sheet Material Conveying Device 114 Open / Close Control Unit (Open / Close Control Unit)
118A Slide rail (sensor moving means)
118B Slide rail (sensor moving means)
120 Sheet material conveying device 124A Motor (sensor moving means)
124B motor (sensor moving means)
128 Motor driver (third control means)
130 Sheet material conveying device 132 Sheet material moving mechanism (sheet material moving means)
144 Motor driver (fourth control means)
140 Sheet material conveying device 148 Sensor rotation mechanism (sensor rotation means)
150 Sheet Material Conveying Device 160 Sheet Material Conveying Device 170 Sheet Material Conveying Device H Hole P Sheet Material

Claims (10)

Conveying means for conveying the sheet material;
Transmitting means for allowing ultrasonic waves to pass through the sheet material conveyed by the conveying means; opposed to the transmitting means across the conveying path of the sheet material; receiving ultrasonic waves transmitted from the transmitting means; A receiving means for outputting a waveform of a sound wave; and an ultrasonic sensor comprising:
A sheet material conveying apparatus comprising: a multi-feed detecting unit that determines multi-feeding of a sheet material based on an ultrasonic waveform output from the receiving unit;
Hole detecting means for detecting holes that are vacated in the sheet material conveyed by the conveying means and pass through a search range of the ultrasonic sensor;
First control means for invalidating the waveform of the ultrasonic wave output from the receiving means before and after the hole detected by the hole detecting means passes through the search range of the ultrasonic sensor;
A sheet material conveying apparatus comprising: A first sheet material detecting means arranged on the upstream side in the transport direction of the search range of the ultrasonic sensor and detecting a sheet material;
A second sheet material detection means that is disposed downstream of the search range of the ultrasonic sensor in the conveying direction and detects a sheet material;
Second control means for enabling the waveform of the ultrasonic wave output from the receiving means only while the sheet material is detected by both the first sheet material detecting means and the second sheet material detecting means;
The sheet material conveying apparatus according to claim 1, wherein Conveying means for conveying the sheet material;
Transmitting means for allowing ultrasonic waves to pass through the sheet material conveyed by the conveying means; opposed to the transmitting means across the conveying path of the sheet material; receiving ultrasonic waves transmitted from the transmitting means; A receiving means for outputting a waveform of a sound wave; and an ultrasonic sensor comprising:
A sheet material conveying apparatus comprising: a multi-feed detecting unit that determines multi-feeding of a sheet material based on an ultrasonic waveform output from the receiving unit;
Hole detecting means for detecting holes that are vacated in the sheet material conveyed by the conveying means and pass through a search range of the ultrasonic sensor;
Sensor moving means for moving the ultrasonic sensor in a direction intersecting with the conveying direction of the sheet material;
Third control means for operating the sensor moving means when the hole is detected by the hole detecting means, and retracting the ultrasonic sensor from the passage position of the hole;
A sheet material conveying apparatus comprising: Conveying means for conveying the sheet material;
Transmitting means for allowing ultrasonic waves to pass through the sheet material conveyed by the conveying means; opposed to the transmitting means across the conveying path of the sheet material; receiving ultrasonic waves transmitted from the transmitting means; A receiving means for outputting a waveform of a sound wave; and an ultrasonic sensor comprising:
A sheet material conveying apparatus comprising: a multi-feed detecting unit that determines multi-feeding of a sheet material based on an ultrasonic waveform output from the receiving unit;
Hole detecting means for detecting holes that are vacated in the sheet material conveyed by the conveying means and pass through a search range of the ultrasonic sensor;
Sheet material moving means for moving the sheet material conveyed by the conveying means in a direction crossing the conveying direction;
Fourth control means for operating the sheet material moving means when the hole is detected by the hole detecting means and retracting the passage position of the hole from the search range of the ultrasonic sensor;
A sheet material conveying apparatus comprising:   The sheet material according to any one of claims 1 to 4, wherein a search range of the hole detecting means is wider than a search range of the ultrasonic sensor in a direction orthogonal to a conveyance direction of the sheet material. Conveying device. The hole detecting means is an optical sensor composed of a light emitting means and a light receiving means for receiving a light beam emitted from the light emitting means,
The optical sensor is attached to a support member that supports the ultrasonic sensor, and the transmitting unit and the receiving unit are aligned using the alignment of the light emitting unit and the light receiving unit. Item 6. The sheet material conveying device according to any one of Items 1 to 5.   The sheet material conveying apparatus according to claim 1, further comprising a transmission / reception selection unit that switches the transmission unit to the reception unit and the reception unit to the transmission unit. Opening and closing means for opening and closing the transmitting surface of the transmitting means and the receiving surface of the receiving means;
Open / close control means for causing the opening / closing means to close the transmitting surface and the receiving surface except during the search of the ultrasonic sensor,
The sheet material conveying device according to claim 1, comprising:   9. The sheet material conveying apparatus according to claim 1, further comprising a sensor rotating unit that rotates the transmitting surface of the transmitting unit or the receiving surface of the receiving unit about an axis extending in a horizontal direction. . A sheet material conveying device according to any one of claims 1 to 9,
Image forming means for forming an image on a sheet material conveyed by the sheet material conveying device;
An image forming apparatus comprising:

Images