JP2007297192A - Double-feed detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-feed detecting device capable of surely detecting double-feed of paper sheets and surely detecting a foreign material or something attached or adhered to a paper sheet. <P>SOLUTION: The double-feed detecting device 10 for detecting whether conveyed paper sheet 22 is one piece or more is provided with an electrostatic capacity sensor 12, a conductive metal target 14 arranged opposite to the electrostatic capacity sensor with a paper sheet conveying passage between them, a comparison section for comparing an output value of the electrostatic capacity sensor with a predetermined threshold value, and a determination section for determining whether the conveyed paper sheet is one piece or more on the basis of a result of the comparison by the comparison section. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for detecting that a plurality of sheets have been conveyed by being overlapped when a sheet is separated from a plurality of sheets and conveyed by a printer, a scanner, or the like.

  2. Description of the Related Art Conventionally, in a device such as a printer or a scanner, there is a paper separation mechanism that separates one sheet from a plurality of printing sheets or reading documents placed on a tray and conveys the separated sheet to a printing unit or a reading unit of a printer. Is provided. In general, the paper separating mechanism rotates a feed roller arranged at the top of the paper in the paper feeding direction, and the separation roller arranged facing the feeding roller in a direction opposite to the paper feeding direction. The paper is separated one by one by the frictional force between the roller and the paper.

  According to such a paper separating mechanism, it is possible to reliably separate one sheet from a plurality of sheets and convey it to the printing unit or the reading unit.

  However, in the paper separating mechanism as described above, in most cases, it is possible to separate the sheets one by one, but a plurality of sheets placed on the tray are strongly attached by a force such as static electricity. In some cases, the sheet cannot be completely separated. That is, there are cases where two or three sheets of paper are collectively conveyed to the printing unit or the reading unit.

In such a case, conventionally, the amount of light transmitted through the transported paper is detected using a transmission type optical sensor, and when the light amount becomes small, the paper is transported in an overlapping manner (multiple feed). A method has been adopted in which a determination is made and the apparatus is stopped according to the determination result. Alternatively, a technique for detecting that the sheets are conveyed while being superposed by an ultrasonic sensor is also known.
JP 2004-359462 A

  However, in the double feed detection method using the transmission type optical sensor and the ultrasonic sensor, the measurement range is limited due to the design of the device or the sensitivity of the sensor. There was a problem that it was not possible to detect the adhered matter.

  In addition, there is a problem in that it is difficult to reliably detect foreign matters such as staples due to restrictions on the specifications of the sensor even if they are foreign matters or deposits within the measurement range.

  In addition, if foreign objects with such detection omissions are taken into the device, foreign materials adhering to the paper may cause device failure, such as abnormal transport paths, reduced character recognition rate, or damage to mechanical parts. Alternatively, it has been strongly desired to reliably detect the deposits.

  Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to reliably detect double feeding of paper and to reliably detect foreign matter or attached matter attached to or attached to the paper. Is to do.

  In order to solve the above-described problems and achieve the object, a multifeed detection apparatus according to the present invention is a multifeed detection apparatus that detects whether or not a single sheet is conveyed, A capacitance sensor, a conductive metal target disposed so as to face the capacitance sensor across the paper conveyance path, and a magnitude of an output value of the capacitance sensor and a predetermined threshold value Comparing means for comparing relationships, and determining means for determining whether or not the number of sheets is one based on a comparison result by the comparing means is provided.

  The multifeed detection device according to the present invention further comprises storage means for storing the predetermined threshold value.

  In the multifeed detection device according to the present invention, the storage unit stores a plurality of the threshold values, and the determination unit compares the output voltage of the capacitance sensor with the plurality of threshold values. Further, it is further characterized in that it is further determined whether or not a foreign matter is attached to the paper.

  In the multifeed detection device according to the present invention, the length of the capacitance sensor across the sheet is set to be substantially the same as the width of the sheet or larger than the width of the sheet. .

    The multi-feed detection apparatus according to the present invention further includes notification means for notifying a user that there are a plurality of sheets or that foreign substances are attached to the sheets.

  According to the present invention, it is possible to reliably detect double feeding of paper and to reliably detect foreign matter or adhering matter attached to or attached to the paper.

  Hereinafter, a preferred embodiment of the double feed detection device of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a multifeed detection device according to an embodiment of the present invention, a paper separation mechanism arranged in the front stage thereof, and a processing device such as a printer or a scanner arranged in the rear stage.

  In FIG. 1, the paper separating mechanism 20 is provided with a tray 24 on which a plurality of printing papers or papers 22 such as reading originals are placed, and the paper 22 arranged in front of the tray 24 is conveyed in the direction indicated by the arrow A. Therefore, a feed roller 26 that rotates in the direction indicated by arrow B, and a separation roller 28 that faces the feed roller 26 and rotates in the direction indicated by arrow C to separate one sheet from the plurality of sheets 22 It has.

  Further, the processing device 30 includes a known printing unit such as an ink jet type or a known image reading unit including a photoelectric conversion sensor, and prints on the paper 22 that has passed through the double feed detection device 10. And a function of reading an image formed on the paper 22.

  The double feed detection device 10 is disposed opposite to the known electrostatic capacitance sensor 12 and the electrostatic capacitance sensor, and the conductive metal target 14 on which the paper 22 is conveyed, and the electrostatic capacitance sensor 12. And a main body frame 16 that supports the metal target 14 and guides the paper 22. The paper 22 is conveyed on the double feed detection device 10 by a roller or a belt (not shown). These rollers, belts, and the like can be disposed in the opening holes by forming necessary opening holes in the metal target as appropriate.

  The multifeed detection device 10 according to the present embodiment detects a sheet that cannot be separated into a single sheet by the paper separation mechanism 20 and has become a plurality of sheets, or a foreign matter or an attached matter attached to the sheet. .

  FIG. 2 is a plan view of the double feed detection device 10 as viewed from above.

  In FIG. 2, the main body frame 16 guides both side edges 22 a and 22 b of the paper 22 to move the paper 22 straight when the paper 22 is conveyed in the arrow A direction. Guides 16a and 16b are provided that are separated by a slightly larger distance. The electrostatic capacity sensor 12 is supported by a bracket extending upward from the guides 16a and 16b. The electrostatic capacitance sensor 12 has a length that is substantially the same as or larger than the width of the paper 22, and is arranged so as to be able to detect paper overlap, foreign matter, adhered matter, etc. over the entire width of the paper 22.

  Next, FIG. 3 is a diagram illustrating an output signal of the capacitance sensor when there is an overlap of sheets, foreign matter, adhered matter, and the like.

  In FIG. 3, as shown in FIG. 1, another sheet 22 d smaller than this sheet overlaps on one sheet 22 c, and a foreign material 22 e such as staples and glue is attached on the sheet. The output signal of the electrostatic capacitance sensor 12 in the case of being performed is shown.

  First, in a state where the sheet 22c has not yet reached the capacitance sensor 12, L1 (V) is output from the capacitance sensor 12 as an output voltage. When the tip of the bottom sheet 22c in FIG. 1 passes the position of the capacitance sensor 12, the capacitance between the capacitance sensor 12 and the metal target 14 changes, and the capacitance sensor 12 The output voltage rises from L1 (V) to L2 (V). Next, when the tip of the second sheet 22d from the bottom in FIG. 1 passes the position of the capacitance sensor 12, the capacitance between the capacitance sensor 12 and the metal target 14 further changes, and the capacitance The output voltage of the sensor 12 increases from L2 (V) to L3 (V). Furthermore, when the tip of a foreign material 22e protruding from the second paper 22d in FIG. 1 passes through the position of the capacitance sensor 12, the capacitance between the capacitance sensor 12 and the metal target 14 is increased. Further, the output voltage of the capacitance sensor 12 increases from L3 (V) to L4 (V).

  Similarly, when the foreign object 22e passes the position of the electrostatic capacity sensor 12, the output voltage of the electrostatic capacity sensor 12 decreases from L4 (V) to L3 (V), and the second sheet 22d from the bottom moves. When the position of the capacitance sensor 12 is passed, the output voltage of the capacitance sensor 12 decreases from L3 (V) to L2 (V). Further, when the lowermost sheet 22c passes the position of the capacitance sensor 12, the output voltage of the capacitance sensor 12 decreases from L2 (V) to L1 (V).

  In this way, it is possible to detect from the change in the output signal of the capacitance sensor that the paper 22 has been sent in a superimposed manner (multiple feed) and that foreign matter and adhered matter are attached to the paper. It becomes.

  Explaining this in more detail, the control unit 46 (see FIG. 4) of the double feed detection device 10 has a threshold TH1 (V), which is slightly higher than the voltage L1 (V), and a voltage L2 (V) as threshold values. The voltage TH2 (V), which is a slightly higher voltage, and the voltage TH3 (V), which is a voltage slightly higher than the voltage L3 (V), are set. The control unit 46 uses these threshold values to determine that there is no sheet 22 when the output voltage S of the capacitance sensor 12 is S <TH1, and one sheet 22 when TH1 ≦ S <TH2. If TH2 ≦ S <TH3, it is determined that two sheets 22 are overlapped. If TH3 ≦ S, the sheet 22 is attached with foreign matter or adhered matter, or three sheets 22 are present. It is determined that there is an overlap. In the case of TH2 ≦ S, it is considered that the paper 22 is being double-fed or that foreign matter and adhering matter are attached to the paper 22, so the control unit 46 controls the paper separation mechanism 20 and the processing device 30. An instruction to stop the operation is issued. When these devices are stopped, the user takes out the double-fed paper or paper attached with foreign matter, adhered matter, etc. from the device, and resets the device.

  Note that the amount of change in the output voltage of the capacitance sensor differs between when there is one sheet of paper and when a foreign object or attached matter is attached, so by increasing the number of thresholds or setting it more finely, Even when one sheet of paper has been conveyed, it is also possible to detect whether or not foreign matter or adhered matter is attached.

  In addition, the paper to be detected may be charged with static electricity, and the output voltage of the capacitance sensor 12 changes depending on the amount of static electricity. The amount of static electricity varies depending on the season, and the amount of static electricity increases especially in winter. However, since the main body frame 16 of the multi-feed detection device 10 is dropped to the ground, the static electricity of the paper does not flow to the ground, and the output fluctuation is rarely caused to cause erroneous detection of the number of sheets. However, as a precaution, the output voltage of the capacitance sensor is monitored while detecting double feeding of the paper, and an appropriate offset amount is added to or subtracted from the threshold value for detecting the number of paper sheets according to fluctuations in the output voltage due to static electricity. You may do it. In this way, it becomes possible to detect the double feed of paper more accurately regardless of the season.

  Next, FIG. 4 is a diagram illustrating a block configuration of a system including the double feed detection device 10, the paper separation mechanism 20, and the processing device 30.

  In FIG. 4, a signal detection circuit 42 for detecting the output voltage of the capacitance sensor 12 is connected to the capacitance sensor 12 and the metal target 14. The output voltage of the capacitance sensor 12 detected by the signal detection circuit 42 is converted into a digital signal by the A / D converter 44 and input to the control unit 46. The control unit 46 compares the above-described thresholds TH1 to TH3 stored in the memory 52 with the output voltage of the capacitance sensor 12, and determines whether one sheet or two sheets are sent. Or, it is determined whether or not the attached matter is attached. The determination result determined by the control unit 46 is displayed on the display unit 48 as a message or a symbol. The setting unit 50 is used for inputting a threshold value or the like obtained from an experiment result or the like by the user to the control unit 46. This input value is held in the memory 52.

  Next, FIG. 5 is a flowchart showing the operation of the system shown in FIG.

  First, when the multifeed / foreign matter detection operation is started, in step S60, the control unit 46 takes in a plurality of threshold values (three threshold values TH1, TH2, TH3 in the present embodiment) stored in the memory 52.

  Next, in step S62, the control unit 46 compares the output voltage S of the capacitance sensor 12 output in real time with each threshold value.

  In step S64, it is determined whether or not the output voltage S of the capacitance sensor 12 is greater than the threshold value TH1.

  If the output voltage S of the capacitance sensor 12 is S ≦ TH1 in step S64, it means that there is no sheet, and the process returns to step S62.

  If the output voltage S of the capacitance sensor 12 is greater than the threshold value TH1 in step S64, the process proceeds to step S66.

  In step S66, it is determined whether or not the output voltage S of the capacitance sensor 12 is greater than the threshold value TH2.

  If the output voltage S of the capacitance sensor 12 is S ≦ TH2 in step S66, it means that there is only one sheet, so that in step S68, one sheet is currently being sent. Is displayed on the display unit 48, and the process returns to step S62.

  If the output voltage S of the capacitance sensor 12 is greater than the threshold value TH2 in step S66, the process proceeds to step S70.

  In step S70, it is determined whether or not the output voltage S of the capacitance sensor 12 is greater than a threshold value TH3.

  If the output voltage S of the capacitance sensor 12 is S ≦ TH3 in step S70, it means that two sheets of paper have been double-fed, so that two sheets of paper are sent in step S74. Is displayed on the display unit 48. In step S76, the apparatus is stopped and the process ends.

  If the output voltage S of the capacitance sensor 12 is S> TH3 in step S70, it means that there is a foreign object or a foreign substance attached to the paper, so that the presence of a foreign object is displayed in step S72. This is displayed on the part 48. In step S76, the apparatus is stopped and the process ends.

  As described above, according to the above-described embodiment, by detecting the value of the output voltage of the capacitance sensor and discriminating the value with a plurality of threshold values, the presence or absence of double feeding of paper, foreign matter and adhered matter is detected. Can be detected effectively.

  In addition, by setting the capacitance sensor to be substantially the same as the width of the paper or larger than the width of the paper, it is possible to detect the presence or absence of double feed of paper, foreign matter, and adhered matter over the entire width of the paper to be conveyed. Is possible.

  In the above-described embodiment, the case where three threshold values are set has been described. However, more threshold values may be set so that the types of foreign matters and adhered substances can be detected more finely.

It is a figure which shows processing apparatuses, such as a double feed detection apparatus of one Embodiment of this invention, the paper separation mechanism arrange | positioned in the front | former stage, and a printer or a scanner arrange | positioned in the back | latter stage. It is the top view which looked at the double feed detection device from the upper part. It is a figure which shows the output signal of an electrostatic capacitance sensor when there exists an overlap of a paper, a foreign material, a deposit, etc. It is a figure which shows the block configuration of the system containing a double feed detection apparatus, a paper separation mechanism, and a processing apparatus. Next, it is a flowchart which shows operation | movement of the system shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Double feed detection apparatus 12 Capacitance sensor 14 Metal target 16 Main body frame 20 Paper separation mechanism 22 Paper 24 Tray 26 Feed roller 28 Separation roller 30 Processing apparatus 42 Signal detection circuit 44 A / D converter 46 Control part 48 Display part 50 Setting part 52 Memory

Claims (5)

A multi-feed detection device that detects whether or not a single sheet has been conveyed,
A capacitance sensor;
A conductive metal target arranged to face the capacitance sensor across the paper conveyance path;
Comparison means for comparing the magnitude relationship between the output value of the capacitance sensor and a predetermined threshold;
Determination means for determining whether or not the number of sheets is one based on a comparison result by the comparison means;
A double feed detection device comprising:   The multifeed detection apparatus according to claim 1, further comprising storage means for storing the predetermined threshold value.   The storage unit stores a plurality of the thresholds, and the determination unit compares the output voltage of the capacitance sensor with the plurality of thresholds to determine whether foreign matter is attached to the paper. The multifeed detection device according to claim 2, further comprising:   The multifeed detection device according to claim 1, wherein a length of the capacitance sensor across the sheet is set to be substantially the same as a width of the sheet or larger than a width of the sheet.   The multifeed detection device according to claim 1, further comprising notification means for notifying a user that there are a plurality of sheets, or that foreign substances are attached to the sheets.

Images