JP2009292549A - Paper sheet conveying device and double feed detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper sheet conveying device capable of correctly detecting only the peak of a primary wave and executing consistent double feed detection. <P>SOLUTION: The paper sheet conveying device has ultrasonic wave sensors 1a, 1b arranged at the opposing positions across a conveying passage on which paper sheets P are conveyed. The ultrasonic wave sensor 1b detects the voltage data a plurality of times at the different timing from the waves received from the ultrasonic sensor 1a, and the peak of the primary wave in the received wave is determined based on a plurality of detected voltage data. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a paper transport device and a multifeed detection method, and more particularly to a paper transport device including an ultrasonic multifeed detection sensor that detects double feed of a paper and a multifeed detection method thereof.

Conventionally, in an ultrasonic double feed detection sensor, the maximum value of a received signal obtained after a burst signal is transmitted is used as a detection timing to increase the detection level difference between double feed and non-double feed. The N ratio is increased so that detection accuracy can be obtained (see, for example, Patent Document 1).
JP 2000-25986 A

  However, depending on the mounting angle and paper type of the transmission sensor and reception sensor that constitute the double feed detection sensor, in addition to the primary wave that reaches the reception signal directly from the transmission side, the reflected wave may be a secondary wave or a tertiary wave. Sound wave component will be included. Therefore, as in the conventional example described above, when the maximum value of the received signal is the detection timing, the secondary wave and the tertiary wave are overlapped with the primary wave. As a result, there is a problem in that stable detection cannot be performed due to the influence of a secondary wave or tertiary wave with unstable intensity.

  Further, the arrival time of the ultrasonic wave varies depending on the time degradation, environmental fluctuation, individual difference of the sensor, or the intensity of the transmitted ultrasonic wave.

  The present invention has been made in view of the above problems, and provides a paper transport device and a multi-feed detection method capable of accurately detecting only the peak of the primary wave and performing stable multi-feed detection. The purpose is to provide.

  In order to achieve the above object, a paper transport apparatus according to claim 1 is provided with a multi-feed detection means comprising ultrasonic transmission means and ultrasonic reception means arranged at positions facing each other across the paper transport path. In the transport device, the ultrasonic wave receiving means detects the voltage data a plurality of times at different timings from the received wave received from the ultrasonic wave transmitting means, and the received wave based on the detected plural voltage data Determining means for determining the peak of the primary wave.

  In order to achieve the above object, a double feed detection method according to claim 6 comprises double feed detection means comprising ultrasonic transmission means and ultrasonic reception means arranged at positions facing each other across the paper conveyance path. In the double feed detection method of the paper conveying apparatus, a detection step in which the ultrasonic reception unit detects voltage data a plurality of times at different timings from the received wave received from the ultrasonic transmission unit, and the detected plurality of voltage data And a determining step for determining a peak of the primary wave in the received wave.

  According to the present invention, in a paper conveying apparatus provided with an ultrasonic double feed detection sensor, only the peak of the primary wave can be accurately detected, and stable double feed detection can be performed.

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

[First Embodiment]
FIG. 1 is a diagram showing a schematic arrangement configuration of ultrasonic double feed detection sensors mounted on a paper conveying apparatus according to a first embodiment of the present invention.

  In the paper transport device in the present embodiment, the paper P is nipped and transported along the transport path by transport rollers 2a, 2b, 3a, and 3b that are driven by a motor and a gear (not shown). The ultrasonic sensors 1a and 1b are arranged at positions facing each other across the conveyance path through which the paper P is conveyed. The ultrasonic sensors 1a and 1b are arranged so that a straight line connecting the ultrasonic sensor 1a as the ultrasonic transmission means and the ultrasonic sensor 1b as the ultrasonic reception means intersects with a predetermined inclination rather than perpendicular to the conveyance path. Has been placed. In this embodiment, they are arranged so as to have an inclination of about 40 degrees with respect to the conveyance path. This is because, when arranged vertically, it is strongly influenced by the ultrasonic waves reflected on the paper and a conveyance guide (not shown), and the stability of the received wave cannot be obtained. However, since it is difficult to prevent the influence of reflection even when the angle is given, it is effective to detect at the timing not affected by the reflected wave by detecting the peak of the primary wave as described below. .

  Next, the primary wave peak detection operation of the double feed detection control circuit in the paper conveying apparatus of FIG. 1 will be described.

  FIG. 2 is a block diagram showing a schematic configuration of a double feed detection control circuit in the paper conveying apparatus of FIG.

  The CPU 201 is a central processing circuit that includes a control program for executing processing and the like to be described later, and performs double feed detection control and overall device control. Primary wave peak detection, which will be described later, is performed by a command from the CPU 201. A RAM 202 is a memory that stores various types of information related to device control, and data writing and reading control is performed by the CPU 201. The ASIC 203 is an integrated circuit that performs a burst transmission control signal and received data sampling control in the double feed detection control, and various load controls of the apparatus. The voltage conversion circuit 207 drives the ultrasonic sensor 1a on the transmission side based on the burst transmission control signal sent from the ASIC 203. In the present embodiment, the voltage conversion circuit 207 converts the 3.3V output voltage from the ASIC 203 to 12V and drives the ultrasonic sensor 1a.

  The amplifying circuit 206 amplifies the voltage of the signal received by the ultrasonic sensor 1b on the receiving side, converts it to an integrated output so that it can be sampled by the A / D (analog / digital conversion circuit) 204 in the integrating circuit 205. Yes. The signal digitally converted by the A / D 204 is captured by the ASIC 203 and stored in the register.

  Next, the primary wave peak detection method in the first embodiment will be described with reference to FIGS.

  FIG. 3 is a diagram showing a received wave when the received wave is sampled at three different timings by the double feed detection control circuit of FIG. 2 to detect a primary wave peak.

  In FIG. 3, the double feed detection control circuit sequentially samples the received wave at three different timings t1, t2, and t3 after the burst wave starts to be transmitted. In the present embodiment, it is assumed that t1, t2, and t3 have a relationship of t1 <t2 <t3 and are set in advance within a time range in which the primary wave peak is received.

  In the example shown in FIG. 3, it can be seen that there is a primary wave peak between t2 and t3. In the present embodiment, the double feed detection control circuit has a primary wave peak between t2 and t3 based on received data (received voltages) Y1, Y2, Y3 detected from the received wave at timings t1, t2, and t3. Detect that there is. Thereby, even if the detection timing of the primary wave peak fluctuates within a predetermined range, only the peak of the primary wave can be accurately detected.

  In this embodiment, the case where control is performed so that the primary wave peak always comes between t2 and t3 will be described. However, as a method of detecting the primary wave peak from the received data detected from the received wave at different timings, Not as long.

  FIG. 4 is a diagram showing an outline of a primary wave peak detection method in the first embodiment.

  It is determined whether or not all of the following conditions 1, 2, and 3 are satisfied for the received data Y1, Y2, and Y3 detected at three different timings t1, t2, and t3. When all the conditions 1 to 3 are satisfied, the satisfying point is set as the primary wave peak detection point. On the other hand, when the conditions 1 to 3 are not satisfied, the detection is performed again by changing the sampling timings of t1, t2, and t3 uniformly in steps.

Condition 1: When (Y3−Y2) <+ 10 mV is not satisfied → Sampling timing is delayed Condition 2: When −10 mV <(Y3−Y2) is not satisfied → Sampling timing is advanced Condition 3: +50 mV <(Y2−Y1) ) Is not satisfied → The sampling timing is advanced. Note that the voltage values in the conditions 1 to 3 are reference values in the present embodiment, and are not limited thereto.

  If there is a primary wave peak between t2 and t3, the voltage difference between the received data Y2 and Y3 will approach 0V. This condition is 1 and 2. In this embodiment, if it is in the range of −10 mV to +10 mV, it is determined that there is a primary wave peak between t2 and t3. Further, when the primary wave peak is between t2 and t3, t1 and t2 are always on the rising waveform, and this rising waveform has a slope of a predetermined value or more. This condition is 3, and it is determined that the potential difference between Y2 and Y1 is +50 mV or more. When the received data Y1 to Y3 are outside the predetermined voltage range, the control is stopped because the ultrasonic sensor may be broken or the apparatus may be abnormal.

  Next, the flow of the primary wave peak detection process described above will be described with reference to the flowchart of FIG.

  FIG. 5 is a flowchart showing the flow of the primary wave peak detection process in the first embodiment.

  First, in order to perform burst transmission control, a burst signal is output from the ASIC 203, and ultrasonic waves are transmitted from the ultrasonic sensor 1a on the transmission side (step S102). When the ultrasonic wave reaches the ultrasonic sensor 1b on the reception side, the ultrasonic sensor 1b vibrates and a reception voltage is generated.

  Next, the reception data Y1 is detected from the reception wave at a timing after the elapse of the predetermined time t1 from the start of transmission of the burst signal in step S102 (step S103). Next, similarly to t1, the received data Y2 and Y3 are detected from the received wave at each timing after the predetermined times t2 and t3 have elapsed (steps S104 and S105).

  Next, the CPU 201 determines whether or not the detected reception data Y1 to Y3 are within a predetermined voltage range of 100 mV to 300 mV (step S106). If this condition is not satisfied, it is determined that the ultrasonic sensor is malfunctioning or the apparatus is abnormal, and the error is stopped (step S115). If the condition is satisfied, it is determined whether (Y2−Y1) is greater than +50 mV (step S107). If this condition is not satisfied (NO in step S107), the sampling timing t1 to t3 is advanced by a predetermined value (step S108), and the processing from step S102 is executed again.

  On the other hand, if the condition is satisfied in step S107 (YES in step S107), it is determined whether (Y3-Y2) is greater than −10 mV (step S109). If this condition is not satisfied (NO in step S109), the time from t1 to t3 is advanced by a predetermined value (step S110), and the processing after step S102 is executed again.

  On the other hand, if the condition is satisfied in step S109 (YES in step S109), it is determined whether (Y3-Y2) is smaller than +10 mV (step S111). When this condition is not satisfied (NO in step S111), the time from t1 to t3 is delayed by a predetermined value (step S112), and the processes after step S102 are executed again.

  On the other hand, if the condition is satisfied in step S111 (YES in step S111), the center time between t2 and t3 is determined as the primary wave peak detection timing (step S113), and this process is terminated.

  According to the first embodiment, the ultrasonic sensor 1b detects voltage data multiple times at different timings from the received wave received from the ultrasonic sensor 1a, and based on the detected voltage data, the primary wave in the received wave Determine the peak of the wave. Thereby, only the peak of the primary wave can be detected accurately, and stable double feed detection can be performed.

  When at least one of the above conditions 1 to 3 is not satisfied, at least one of the three different timings is advanced or delayed by a predetermined time. This makes it possible to accurately detect only the peak of the primary wave.

[Second Embodiment]
FIG. 6 is a block diagram showing a schematic configuration of a double feed detection control circuit in the paper conveying apparatus according to the second embodiment of the present invention. Note that the same components as those in the double feed detection control circuit of FIG. Only differences from the first embodiment will be described below.

  In the double feed detection control circuit according to the second embodiment, the integration circuit 205 and the ASIC 203 are connected via a comparator 208. The comparator 208 includes a peak hold circuit that holds (holds) the peak of the output signal voltage of the integration circuit 205, and a threshold circuit (threshold determination means) that determines a threshold voltage based on the peak-held voltage.

  Next, a primary wave peak detection method in the second embodiment will be described with reference to FIG.

  FIG. 7 is a diagram illustrating an outline of a primary wave peak detection method according to the second embodiment.

  The comparator 208 peaks the output signal voltage from the integrating circuit 205 and determines a level of 90% of the hold value as a threshold voltage. In the present embodiment, the ratio is set to 90%, but it is not limited to this because it needs to be examined according to the device configuration.

  As shown in the figure, the waveform of the output signal of the comparator 208 becomes H in synchronization with the rising of the received wave, and becomes L at the timing of 90% falling after the passage of the primary wave peak. Subsequently, the logical value is switched to H because the threshold is exceeded at the rising edge at which the secondary wave is received. Even after the secondary wave peak, the logical value switches to L again at the 90% level as in the primary wave. Thereafter, in the example of the received waveform as shown in FIG. 7, the comparator output does not change because it attenuates without exceeding the threshold value.

  In the present embodiment, the ASIC 203 counts the time from when the burst signal is output from the ASIC 203 to the time when the comparator 208 output first switches to L in order to perform burst transmission control. A time earlier than the count value by a predetermined time N is determined as the primary wave peak detection timing.

  Next, the flow of the primary wave peak detection process in the second embodiment will be described with reference to the flowchart of FIG.

  FIG. 8 is a flowchart showing the flow of the primary wave peak detection process in the second embodiment.

  First, a burst signal is output from the ASIC 203 (step S202). Next, in synchronization with the start of burst signal output, a timer counter (not shown) in the ASIC 203 starts counting (step S203). Next, the ASIC 203 performs the counter operation until the Low edge of the output of the comparator 208 is detected, that is, until the output of the comparator 208 first switches to L (step S204). When the Low edge is detected (YES in step S204), the timer counter is stopped (step S205). Then, a value obtained by subtracting the predetermined value N from the timer count value is determined as the primary wave peak detection timing (step S206), and the present process is terminated.

  According to the second embodiment, the ultrasonic sensor 1b holds the voltage peak in the received wave received from the ultrasonic sensor 1a. Then, the threshold voltage is determined based on the held voltage. Furthermore, the timing at which the voltage of the received wave becomes the threshold voltage is counted, and the peak of the primary wave in the received wave is determined based on the counted value. As a result, even when the detection timing of the primary wave peak varies greatly due to the influence of the apparatus environment, individual differences, etc., it is possible to accurately determine the detection timing of the primary wave peak.

  The sheet conveying apparatus in the first and second embodiments may be applied to an image forming apparatus. In this case, when detecting the primary wave peak, a means for changing the transmission control may be provided so as to be different from the ultrasonic transmission amount during the normal printing operation. As a result, the reception voltage, which is saturated because the transmission intensity of the ultrasonic sensor is too strong when there is no paper, can be lowered to a level where the primary wave peak can be detected, and the primary wave peak can be detected even without paper. .

  The object of the present invention is achieved by executing the following processing. That is, a storage medium that records a program code of software that realizes the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU, MPU, etc.) of the system or apparatus is stored in the storage medium. This is the process of reading the code. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the program code and the storage medium storing the program code constitute the present invention.

  Moreover, the following can be used as a storage medium for supplying the program code. For example, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM or the like. Alternatively, the program code may be downloaded via a network.

  Further, the present invention includes a case where the function of the above-described embodiment is realized by executing the program code read by the computer. In addition, an OS (operating system) running on the computer performs part or all of the actual processing based on an instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Is also included.

  Furthermore, a case where the functions of the above-described embodiment are realized by the following processing is also included in the present invention. That is, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

FIG. 2 is a diagram illustrating a schematic arrangement configuration of an ultrasonic double feed detection sensor mounted on a paper conveyance device according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a schematic configuration of a double feed detection control circuit in the paper conveying apparatus of FIG. 1. It is the figure which showed the received wave at the time of detecting a primary wave peak by sampling a received wave at three different timings by the double feed detection control circuit of FIG. It is a figure which shows the outline of the detection method of the primary wave peak in 1st Embodiment. It is a flowchart which shows the flow of the primary wave peak detection process in 1st Embodiment. FIG. 6 is a block diagram illustrating a schematic configuration of a double feed detection control circuit in a paper transport device according to a second embodiment of the present invention. It is a figure which shows the outline of the detection method of the primary wave peak in 2nd Embodiment. It is a flowchart which shows the flow of the primary wave peak detection process in 2nd Embodiment.

Explanation of symbols

1a, 1b Ultrasonic sensor 2a, 2b Conveying roller 3a, 3b Conveying roller 201 CPU
202 RAM
203 ASIC
204 A / D
205 Integration Circuit 206 Amplification Circuit 207 Voltage Conversion Circuit

Claims (10)

In a paper transport apparatus comprising double feed detection means composed of ultrasonic wave transmission means and ultrasonic wave reception means arranged at positions facing each other across the paper transport path,
Detecting means for detecting voltage data a plurality of times at different timings from the received wave received by the ultrasonic wave receiving means from the ultrasonic wave transmitting means;
And a determining unit that determines a peak of a primary wave in the received wave based on the detected plurality of voltage data.   The said determination means determines the peak of the said primary wave based on the voltage data which exists in a predetermined voltage range, after the burst signal for performing burst transmission control is output. Paper transport device.   The determination means determines the detection timing of the peak of the primary wave when all of a plurality of preset conditions are satisfied among the voltage data within the predetermined voltage range, and at least one of the plurality of conditions is determined. 3. The sheet conveying apparatus according to claim 2, wherein when at least one of the timings is not satisfied, at least one of the timings is advanced or delayed by a predetermined time. In a paper transport apparatus comprising double feed detection means composed of ultrasonic wave transmission means and ultrasonic wave reception means arranged at positions facing each other across the paper transport path,
Holding means for holding a voltage peak in the received wave received by the ultrasonic wave receiving means from the ultrasonic wave sending means;
Threshold determination means for determining a threshold voltage based on the held voltage;
Counting means for counting the timing at which the voltage of the received wave becomes the threshold voltage;
And a determining unit that determines a peak of the primary wave in the received wave based on the counted value. The counting means starts counting after a burst signal for performing burst transmission control is output,
5. The paper conveying apparatus according to claim 4, wherein the determining means determines a value obtained by subtracting a predetermined value from the counted value as a detection timing of the peak of the primary wave. In a double feed detection method for a paper transport device comprising a double feed detection means comprising an ultrasonic transmission means and an ultrasonic reception means arranged at positions facing each other across a paper transport path,
A detecting step in which the ultrasonic receiving means detects voltage data a plurality of times at different timings from the received wave received from the ultrasonic transmitting means;
And a determining step of determining a peak of a primary wave in the received wave based on the plurality of detected voltage data.   7. The peak of the primary wave is determined in the determining step based on voltage data within a predetermined voltage range after a burst signal for performing burst transmission control is output. Double feed detection method.   The determination step determines a detection timing of the peak of the primary wave when all of a plurality of preset conditions are satisfied among the voltage data within the predetermined voltage range, and at least one of the plurality of conditions is determined. The multifeed detection method according to claim 7, wherein if at least one of the timings is not satisfied, at least one of the timings is advanced or delayed by a predetermined time. In a double feed detection method for a paper transport device comprising a double feed detection means comprising an ultrasonic transmission means and an ultrasonic reception means arranged at positions facing each other across a paper transport path,
A holding step for holding a voltage peak in a received wave received by the ultrasonic wave receiving means from the ultrasonic wave sending means;
A threshold value determining step for determining a threshold voltage with reference to the held voltage;
A counting step of counting the timing at which the voltage of the received wave becomes the threshold voltage;
And a determining step of determining a peak of the primary wave in the received wave based on the counted value. The counting step starts counting after a burst signal for performing burst transmission control is output,
The multifeed detection method according to claim 9, wherein the determining step determines a value obtained by subtracting a predetermined value from the counted value as a detection timing of the peak of the primary wave.

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