JP2013049513A - Paper feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influence of noise upon ultrasonic multi-feed determination without adding a receiving element for detecting noise.SOLUTION: An ultrasonic wave transmitting element 1 is provided near a conveyance path of a sheet to be fed, and transmits an ultrasonic wave of predetermined frequency to the conveyance path. An ultrasonic wave receiving element 2 is provided near the conveyance path of the sheet to be fed, and receives the ultrasonic wave transmitted from the ultrasonic wave transmitting element 1. In the feeding device, there exists an internal device 9 that operates at frequency nearly the same as the predetermined frequency of the ultrasonic wave, frequency that becomes nearly the same as the frequency of the ultrasonic wave when it is integer-multiplied, or frequency nearly the same as the integer-multiplied frequency of the frequency of the ultrasonic wave. A CPU 8 causes the operation of the internal device 9 to stop in a period in which the ultrasonic wave is transmitted from the ultrasonic wave transmitting element 1.

Description

  The present invention relates to a paper feeding device.

  In ultrasonic double feed detection, an ultrasonic transmission element transmits an ultrasonic wave to an ultrasonic reception element disposed across the conveyance path of a sheet feeding sheet, and is based on the detection result of the ultrasonic wave by the ultrasonic reception element. In this way, double feeding of the sheet is detected. The intensity of ultrasonic waves detected by the ultrasonic wave receiving element increases because the amount of attenuation of ultrasonic waves increases when there are multiple paper sheets (that is, during multi-feed) than when there is only one paper sheet. Based on this, double feeding of the sheet feed sheet is detected.

  In a certain device, two receiving elements are provided, one of the receiving elements detects noise such as electromagnetic noise and vibration, and when the noise level is low, based on the intensity of the ultrasonic wave received by the other receiving element. Double feed determination is performed (see, for example, Patent Document 1). Alternatively, two receiving elements are provided, one of the receiving elements detects noise such as electromagnetic noise and vibration, the threshold is changed according to the noise level, and the intensity of the ultrasonic wave received by the other receiving element And double feed determination is performed (see, for example, Patent Document 1).

JP 2005-15121 A

  However, in the above-described apparatus, it is necessary to add a noise detection receiving element, which increases the cost of the apparatus.

  The present invention has been made in view of the above problems, and an object of the present invention is to obtain a paper feeding device that reduces the influence of noise without adding a noise detection receiving element.

  In order to solve the above problems, the present invention is configured as follows.

  The sheet feeding device according to the present invention is provided near the conveyance path of the sheet feeding sheet, and is disposed near the conveyance path of the sheet feeding sheet and an ultrasonic transmission element that transmits ultrasonic waves of a predetermined frequency toward the conveyance path. An ultrasonic receiving element that receives ultrasonic waves transmitted from the ultrasonic transmitting element, a frequency that is substantially the same as the predetermined frequency of the ultrasonic wave, a frequency that is substantially the same as the ultrasonic frequency when multiplied by an integer, or the super frequency An internal device that operates at a frequency that is substantially the same as an integer multiple of the frequency of the sound wave, and a control unit that stops the operation of the internal device during a period in which the ultrasonic wave is transmitted from the ultrasonic wave transmitting element.

  Thereby, it is possible to reduce the influence of noise from a specific internal device that causes double feed erroneous detection. Therefore, the influence of noise is reduced without adding a noise detection receiving element (that is, while suppressing an increase in the cost of the apparatus).

  In addition to the paper feeding device described above, the paper feeding device according to the present invention may be configured as follows. In this case, the internal device operates according to the clock signal, and the control unit stops the supply of the clock signal to the internal device during the period in which the ultrasonic wave is transmitted from the ultrasonic wave transmitting element.

  In addition to the above paper feeding device, the paper feeding device according to the present invention may be as follows. In this case, the control unit stops the supply of power to the internal device during a period in which the ultrasonic wave is transmitted from the ultrasonic wave transmitting element.

  In addition to the above paper feeding device, the paper feeding device according to the present invention may be as follows. In this case, the internal device is a sensor that is provided in the conveyance path of the sheet feeding sheet and detects the conveyance timing of the sheet feeding sheet by emitting measurement light at a predetermined frequency and detecting reflected light corresponding to the measurement light. .

  In addition to the above paper feeding device, the paper feeding device according to the present invention may be as follows. In this case, the sheet feeding device transmits a multi-feed of sheet feeding sheets based on the band-pass filter that transmits the same frequency component as the above-mentioned predetermined frequency among the outputs of the ultrasonic receiving element, and the output of the band-pass filter. And a determination unit for determining presence or absence.

  Thereby, the influence of the noise of frequencies other than the frequency of an ultrasonic wave can be reduced.

  According to the present invention, in the paper feeding device, the influence of noise is reduced without adding a noise detection receiving element.

FIG. 1 is a block diagram illustrating a configuration of a sheet feeding device according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.

  FIG. 1 is a block diagram illustrating a configuration of a sheet feeding device according to an embodiment of the present invention. In FIG. 1, a portion related to double feed detection is drawn in the paper feeding device. The paper feeding device according to the embodiment is built in, for example, a printer, a copier, a facsimile machine, or a multifunction machine.

  This paper feeding device includes an ultrasonic transmission element 1, an ultrasonic reception element 2, an oscillation circuit 3, a band pass filter 4, an amplification circuit 5, an integration circuit 6, an A / D (Analog to Digital) conversion circuit 7, a CPU (Central Processing Unit) 8 and an internal device 9.

  The ultrasonic transmission element 1 is provided in the vicinity of a conveyance path of a sheet feeding sheet such as printing paper, and transmits ultrasonic waves having a predetermined frequency (for example, 300 kHz) toward the conveyance path. The ultrasonic wave receiving element 2 is provided in the paper feed sheet conveyance path, and receives ultrasonic waves transmitted from the ultrasonic wave transmitting element 1.

  The oscillation circuit 3 oscillates a drive signal for the ultrasonic transmission element 1 and applies it to the ultrasonic transmission element 1.

  The band-pass filter 4 transmits the same frequency component as the predetermined frequency of the ultrasonic wave transmitted from the ultrasonic transmission element 1 in the output signal of the ultrasonic reception element 1.

  The amplifier circuit 5 is a circuit that amplifies the output signal of the bandpass filter 4, and the integrating circuit 6 is a circuit that integrates the amplified output signal of the bandpass filter 4. The A / D conversion circuit 7 converts the output signal of the integration circuit 6 into a digital signal and supplies it to the CPU 8.

  The CPU 8 operates according to a program recorded in a recording medium (not shown) (ROM (Read Only Memory), flash memory, etc.) and controls internal circuits such as the oscillation circuit 3 and the internal device 9.

  The CPU 8 supplies a clock signal to the oscillating circuit 3 to operate the oscillating circuit 3 and transmits ultrasonic waves from the ultrasonic transmitting element 1. Therefore, the CPU 8 can perform on / off control of ultrasonic transmission from the ultrasonic transmission element 1 via the oscillation circuit 3. In this embodiment, the CPU 8 supplies a clock signal to the internal device 9 to operate the internal device 9. Therefore, the CPU 8 can perform on / off control of the operation of the internal device 9.

  The CPU 8 temporarily stops the operation of the internal device 9 during a period in which ultrasonic waves are transmitted from the ultrasonic transmission element 1. In the first embodiment, the CPU 8 stops the operation of the internal device 9 by stopping the supply of the clock signal to the internal device 9.

  Further, the CPU 8 determines the presence or absence of double feeding based on the output signal of the A / D conversion circuit 7. Therefore, the amplifier circuit 5, the integration circuit 6, the A / D conversion circuit 7, and the CPU 8 function as a determination unit that determines the presence / absence of double feeding of the sheet feeding sheet based on the output of the band pass filter 4.

  The internal device 9 is present inside the apparatus in which the paper feeding device is built, and is substantially the same frequency as the predetermined frequency of the ultrasonic wave transmitted by the ultrasonic wave transmitting element 1, and approximately the ultrasonic frequency when multiplied by an integer. It operates at a frequency that is the same or a frequency that is substantially the same as an integer multiple of the ultrasonic frequency.

  For example, the internal device 9 is provided in a conveyance path for a sheet feeding sheet, and is a reflective type that emits measurement light at a predetermined frequency and detects reflected light corresponding to the measurement light to detect conveyance timing of the sheet feeding sheet. It is a photo sensor.

  The internal device 9 uses the same power supply as the ultrasonic transmission element 1, the ultrasonic reception element 2, the oscillation circuit 3, the band-pass filter 4, the amplification circuit 5, the integration circuit 6, the A / D conversion circuit 7, the CPU 8, and the like. Therefore, the power supply voltage slightly fluctuates at the same frequency as the operating frequency of the internal device 9 (or the same frequency and its higher harmonic frequency), which causes noise in those elements and circuits. In addition, depending on the type of the internal device 9, electromagnetic waves or vibrations are generated at the same frequency as the operating frequency of the internal device 9 (or the same frequency and a harmonic frequency of the same frequency). Causes noise. Since these noises have the same frequency component as the ultrasonic frequency, they are not removed by the band-pass filter 4 or the like and cause double feed erroneous detection.

  Next, the operation of determining the double feed in the paper feeder will be described.

  The CPU 8 refers to an output signal of a conveyance timing sensor (not shown) and the like, and starts the multi-feed determination when the sheet reaches a predetermined position in the conveyance path.

  The CPU 8 starts supplying the clock signal to the oscillation circuit 3 and stops supplying the clock signal to the internal device 9.

  When the clock signal is supplied, the oscillation circuit 3 generates a drive signal having a predetermined frequency and applies it to the ultrasonic transmission element 1. Thereby, an ultrasonic wave having a predetermined frequency is transmitted from the ultrasonic wave transmitting element 1. This ultrasonic wave is transmitted while being attenuated by the sheet, and reaches the ultrasonic receiving element 2.

  The ultrasonic receiving element 2 receives the ultrasonic wave and outputs a signal having an amplitude corresponding to the intensity of the received ultrasonic wave. The band pass filter 4 outputs a signal obtained by attenuating a frequency component other than the same frequency component as that of the above-described ultrasonic wave from the output signal of the ultrasonic receiving element 2, and the amplifier circuit 5 amplifies the signal. To the integration circuit 6. The integration circuit 6 integrates the signal and outputs a signal indicating the integration value at each time point to the A / D conversion circuit 7.

  The CPU 8 determines from the waveform of the output signal of the A / D conversion circuit 7 (that is, the temporal change in the integration of the output signal of the bandpass filter 4) whether or not double feeding is performed.

  When this determination is completed, the CPU 8 stops the supply of the clock signal to the oscillation circuit 3 and restarts the supply of the clock signal to the internal device 9.

  As described above, according to the first embodiment, the ultrasonic transmission element 1 is provided in the vicinity of the conveyance path of the sheet feeding sheet, transmits ultrasonic waves of a predetermined frequency toward the conveyance path, and receives ultrasonic waves. The element 2 is provided in the vicinity of the sheet feeding sheet conveyance path, and receives the ultrasonic waves transmitted from the ultrasonic transmission element 1. In the apparatus, there is an internal device 9 that operates at a frequency that is substantially the same as the predetermined frequency of the ultrasonic wave, or a frequency that is substantially the same as the ultrasonic frequency when multiplied by an integer, and the CPU 8 includes the ultrasonic wave transmitting element 1. The operation of the internal device 9 is stopped during the period in which the ultrasonic wave is transmitted from.

  Thereby, it is possible to reduce the influence of noise from the specific internal device 9 that causes double feed erroneous detection. Therefore, the influence of noise is reduced without adding a noise detection receiving element (that is, while suppressing an increase in the cost of the apparatus).

Embodiment 2. FIG.

  In the sheet feeding device according to the second embodiment of the present invention, the CPU 8 stops the supply of power to the internal device 9 during the period in which the ultrasonic wave is transmitted from the ultrasonic wave transmitting element 1, and in that period The operation of the internal device 9 is stopped. Since the other configuration and operation of the sheet feeding device according to the second embodiment are the same as those of the first embodiment, description thereof is omitted.

  Each embodiment described above is a preferred example of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. It is.

  For example, in the first and second embodiments, the other internal device 9 may be a fan in the apparatus and its drive circuit. In that case, the CPU 8 similarly stops the operation of the fan and its drive circuit during the period during which the double feed determination is being performed.

  The present invention is applicable to, for example, a printer, a scanner, a copier, a facsimile machine, a multifunction machine, and the like.

DESCRIPTION OF SYMBOLS 1 Ultrasonic transmission element 2 Ultrasonic reception element 4 Band pass filter 5 Amplification circuit (a part of example of a determination part)
6 Integration circuit (part of an example of the judgment unit)
7 A / D conversion circuit (part of an example of determination unit)
8 CPU (a part of an example of a control part and a judgment part)
9 Internal devices

Claims (5)

In a paper feed device that detects double feeding of paper feed sheets,
An ultrasonic transmission element that is provided in the vicinity of the conveyance path of the sheet feeding sheet and transmits ultrasonic waves of a predetermined frequency toward the conveyance path;
An ultrasonic receiving element that is provided near the conveyance path of the sheet feeding sheet and receives an ultrasonic wave transmitted from the ultrasonic transmitting element;
An internal device that operates at a frequency that is substantially the same as the predetermined frequency of the ultrasonic wave, a frequency that is substantially the same as the frequency of the ultrasonic wave when multiplied by an integer, or a frequency that is substantially the same as an integer multiple of the frequency of the ultrasonic wave. ,
A control unit for stopping the operation of the internal device during a period in which the ultrasonic wave is transmitted from the ultrasonic wave transmitting element;
A sheet feeding device comprising: The internal device operates according to a clock signal;
The control unit stops supplying the clock signal to the internal device in a period in which the ultrasonic wave is transmitted from the ultrasonic wave transmitting element;
The paper feeding device according to claim 1.   The sheet feeding apparatus according to claim 1, wherein the control unit stops supply of power to the internal device during a period in which the ultrasonic wave is transmitted from the ultrasonic wave transmitting element.   The internal device is a sensor that is provided in a conveyance path of the sheet feeding sheet and detects a conveyance timing of the sheet feeding sheet by emitting measurement light at a predetermined frequency and detecting reflected light corresponding to the measurement light. The sheet feeding device according to claim 1, wherein the sheet feeding device is provided.   A band-pass filter that transmits the same frequency component as the predetermined frequency in the output of the ultrasonic receiving element, and a determination unit that determines the presence / absence of double feeding of the paper sheet based on the output of the band-pass filter The sheet feeding device according to any one of claims 1 to 4, further comprising:

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