JP2002362783A - Paper sheet double feed detecting device, method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the double feed when paper sheets of various thickness and length are conveyed in a mixed state. SOLUTION: A length of paper sheet delivered in each job is independently detected and stored. When the double feed does not occur, the length of the paper measured in each job is constant, for example, a first sheet is 200 mm, a second sheet is 200 mm, a third sheet is 220 mm, a fourth sheet is 250 mm, a fifth sheet is 200 mm, and a sixth sheet is 220 mm. On the other hand, when the double feed occurs on the second sheet in a third job, for example, a result of the detection of the length of the paper in delivering the second sheet becomes 300 mm, which is different from the result of the former length of 200 mm. The double feed is determined when a value different from the former length is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus, a method and a program for detecting a double feed of paper sheets, and more particularly to a method of detecting a plurality of paper sheets of different types when the paper sheets are conveyed in a printing machine or the like. The present invention relates to an apparatus, a method, and a program for detecting a double feed, which can easily and surely detect a double feed.

[0002]

2. Description of the Related Art When printing on paper in a printing machine or the like, printing is performed for each paper. If multiple sheets are conveyed at the same time, correct printing cannot be performed.If multiple sheets are conveyed at the same time, detect this as a double feed and temporarily suspend printing. Is performed.

Conventionally, such multi-feeding has been detected by detecting the thickness of a sheet and detecting that the thickness is equal to or larger than a preset reference value.

There is also a method in which the length of a sheet is detected, and when the length of the sheet is equal to or greater than a preset reference value, this is detected as a double feed.

[0005]

However, for example, when printing one book in the order of pages,
The first page is thick because it is a cover, and is often larger in size than the body.

On the other hand, the paper on which the text is printed is
It is often thinner and slightly smaller than the cover.

As described above, when a plurality of types of paper having different sizes and thicknesses are mixed in each job (that is, when the printing paper is mixed paper), the double feed is reliably performed only by the thickness and the length. There was a problem that could not be detected.

The present invention has been made in view of such a situation, and it is an object of the present invention to easily and surely detect a double feed even when conveying mixed paper.

[0009]

[Means for Solving the Problems]

A sheet multi-feed detecting apparatus according to the present invention includes a sheet detecting means for detecting a characteristic of a sheet to be conveyed, and a sheet for each job as a unit for repeatedly conveying a plurality of sheets. Storage means for storing the result detected by the detection means; comparison means for comparing the detection result of the current job detected by the sheet detection means with the detection result of the previous job stored in the storage means And double feed detecting means for detecting double feed of paper sheets based on a comparison result by the comparing means.

The paper sheet is, for example, a sheet 4 shown in FIG.
1, the paper 41A and 41B shown in FIG. The paper is not limited to paper, but may be cloth or plastic.

The sheet detecting means includes, for example, the sheet detecting sensor 32 in FIG. 2 and the sheet thickness detecting sensor 5 in FIG.
1. Ultrasonic transmitter 61 and ultrasonic receiver 6 in FIG.
2. That is, the detection target of the paper sheet is not limited to the thickness and the length, but may be the light reflectance or the transmittance.

A job is a unit for repeatedly transporting a set of a plurality of paper sheets. For example, when one book is printed in order from the front cover to the back cover, the paper sheet from the front cover to the back cover is used. Is one job.

The storage means comprises, for example, the memory 22 shown in FIG.

The comparing means is, for example, a step S in FIG.
7, Step S27 in FIG. 10, Step S47 in FIG.
Is performed by the CPU 21 of FIG.

The double feed detecting means includes, for example, step S10 in FIG. 4, step S30 in FIG. 10, step S30 in FIG.
The CPU 21 of FIG.

In the sheet multi-feed detecting apparatus, the result detected by the sheet detecting means is stored for each job, and the detection result of the current job and the stored result of the previous job are stored. Are compared, and based on the result of the comparison, double feed of paper sheets is detected.

Therefore, even when a plurality of sheets conveyed in one job are so-called mixed sheets having different lengths and thicknesses, it is possible to easily and surely detect the double feed. Becomes possible.

When detecting the length of a paper sheet, for example, as shown in FIG. 2, a paper detection sensor 32 is used as a paper sheet detecting means.

When detecting the thickness of a paper sheet, for example, a paper thickness detection sensor 51 as shown in FIG. 9 is used.

Further, when at least one of the level and the phase of the ultrasonic wave transmitted through the paper sheet is detected, for example, FIG.
Two ultrasonic transmitters 61 and ultrasonic receivers 62 are used.

The thickness of a sheet or the level and phase of an ultrasonic wave are measured a plurality of times at a plurality of timings when one sheet is conveyed, and an average value thereof can be used. This enables more accurate detection.

It is also possible to combine the detection based on the length, thickness, level and phase of the ultrasonic wave.

The method for detecting a double feed of sheets according to the present invention includes a sheet detecting step for detecting a characteristic of a sheet to be conveyed, and a sheet for each job as a unit for repeatedly conveying a plurality of sheets. A storage step for storing a result detected by the processing of the detection step, a detection result of the current job detected by the processing of the sheet detection step, and a detection result of a previous job stored by the processing of the storage step And a double feed detection step of detecting a double feed of paper sheets based on the comparison result of the processing of the comparison step.

According to the program of the present invention, the result obtained by the processing of the obtaining step of obtaining the detection result of the characteristic of the conveyed paper sheets and the obtaining step for each job as a unit for repeatedly conveying a plurality of paper sheets is obtained. A comparison step of comparing the detection result of the current job acquired by the processing of the acquisition step with the detection result of the previous job stored by the processing of the storage step, and the processing of the comparison step And a double feed detecting step of detecting a double feed of paper sheets based on the comparison result by the computer.

The sheet detecting step and the obtaining step include, for example, steps S2 and S3 in FIG. 4, steps S22 to S24 in FIG. 10, and steps S42 to S24 in FIG.
44.

The storage step includes, for example, step S5 in FIG. 4, step S25 in FIG. 8, and step S45 in FIG.
It consists of.

The comparison step includes, for example, step S7 in FIG. 4, step S27 in FIG. 10, and step S4 in FIG.
7.

The double feed detecting step includes, for example, step S10 in FIG. 4, step S30 in FIG. 10, and step S50 in FIG.

Also in this case, the same operation and effect as those of the sheet multi-feed detecting device can be realized.

[0031]

FIG. 1 shows the configuration of a printing system to which the present invention is applied. In this configuration, printing by the printing machine 2 is performed by a personal computer (PC) 1.
Is controlled by

That is, different types of paper 41 (FIG. 2) used for printing in each job are set in advance on each tray (not shown) of the printing press 2. The personal computer 1 controls the printing press 2 to execute printing in units of jobs.

FIG. 2 mainly shows the configuration of the paper transport section inside the printing press 2. CPU (Central Processing Un
It) 21 is controlled by the personal computer 1 and controls printing inside the printing press 2. The memory 22
For example, RAM (Random Access Memory) and EEPROM (Elect
orically Erasable Programmable Read Only Memory)
It consists of.

The input / output interface 23 supplies a signal from the CPU 21 to the motor driver 24 and supplies an output of the paper detection sensor 32 to the CPU 21.

The motor driver 24 drives and rotates the motor 25. The rotation of the motor 25 is transmitted to the transport roller 27 by the belt 26, and the rotation of the transport roller 27 is transmitted to the transport roller 28 via the belt 29.
A transport roller 30 is pressed against the transport roller 27, and a transport roller 31 is pressed against the transport roller 28.
Transport roller 27 and transport roller 30, or transport roller 2
8 and the transport roller 31 are provided between the paper 41
, And in the case of this example, it is conveyed from right to left.

Printing is performed on the conveyed sheet 41 by a printing unit (not shown).

In this case, the paper detection sensor 32 irradiates the paper 41 with light, and outputs a signal corresponding to the light receiving level of the reflected light on the paper 41 to the CPU 21 via the input / output interface 23.

FIG. 3 shows the configuration of the personal computer 1. In FIG. 3, the CPU (Central Processin
g Unit) 121 is a program stored in a ROM (Read Only Memory) 122 or an RA
Various processes are executed in accordance with a program loaded in an M (Random Access Memory) 123. The RAM 123 also appropriately stores data necessary for the CPU 121 to execute various processes.

CPU 121, ROM 122, and RAM 123
Are connected to each other via a bus 124. The bus 124 is also connected to an input / output interface 125.

The input / output interface 125 includes an input unit 126 including a keyboard and a mouse, a display including a CRT and an LCD, an output unit 127 including a speaker, a storage unit 128 including a hard disk, a modem, and a terminal. A communication unit 129 including an adapter or the like is connected. The communication unit 129 performs a communication process with the printing press 2.

A drive 130 is connected to the input / output interface 125 as necessary.
41, an optical disk 142, a magneto-optical disk 143, a semiconductor memory 144, or the like is appropriately mounted, and a computer program read therefrom is installed in the storage unit 128 as necessary.

Next, referring to the flowchart of FIG.
The operation will be described.

This process is basically executed by the CPU 21 under the control of the personal computer 1.

When the CPU 21 instructs the personal computer 1 to start printing, the input / output interface 2
3 to control the motor driver 24 to drive the motor 25. Since the rotation of the motor 25 is transmitted to the transport roller 27 via the belt 26 and the rotation of the transport roller 27 is transmitted to the transport roller 28 via the belt 29, the sheet 41 is moved between the transport roller 27 and the transport roller 30. The sheet is conveyed between the conveying rollers 28 and 31.
And transported sequentially.

First, in step S1, the CPU 21
Initializes the variable CT for counting the number of printed sheets 41 (the number of conveyed sheets) in each job to zero.

In step S2, the CPU 21 determines whether a sheet has been detected. If the paper 41 is not detected, it waits until it is detected.

That is, the paper detection sensor 32 detects that the paper 41
Light is radiated toward the transport path of the optical path, and the reflected light is received. When the paper 41 has not yet reached the light irradiation position,
Since most of the irradiated light does not return, the level of the received light signal is extremely small. On the contrary,
When the paper 41 reaches the light irradiation position, the paper detection sensor 3
Since the light emitted from 2 is reflected by the paper 41 and returns, the level of the reflected light (therefore, the level of the corresponding light receiving signal) increases. The output of the paper detection sensor 32 is input to the CPU 21 via the input / output interface 23. The CPU 21 compares the input with the reference value, and determines that the paper 41 has been detected when the input level is equal to or higher than the reference value.

When the paper 41 is detected, the CPU 21
The time t1 of the built-in timer is stored in the memory 22.

Next, proceeding to step S3, the CPU 21
It is determined whether the paper 41 has run out. If the paper 41 has not run out, the process waits until the paper 41 runs out.

That is, from the detection of the leading end of the paper 41 by the processing in step S2, the movement of the paper 41 until the rear end of the paper 41 passes the detection position of the paper detection sensor
Although the level of the reflected light from the paper is large, when the rear end of the paper 41 passes through the detection position of the paper detection sensor 32, the amount of the reflected light decreases from that time. It is possible to detect that the sensor 32 has passed the detection position of the sensor 32.

When the CPU 21 detects the trailing edge of the sheet 41, the time t 2 is stored in the memory 22.

Next, proceeding to step S4, the CPU 21
The value of the variable CT initialized in the processing of step S1 is incremented by one. In this case, CT = 1. That is, the first sheet of the current job (in this case, the first job) is substituted into the variable CT.

In step S 5, the CPU 21 calculates the length data of the paper 41 and stores it in the memory 22.
The length data _LCT is calculated by the following equation.

L _CT = (t2−t1) / V

Here, V represents the transport speed of the paper 41. As described above, time t2 represents the time at which the trailing edge of the paper 41 is detected by the processing of step S3, and time t1 is the time at which the leading edge of the paper 41 is detected by the processing of step S2. Indicates the time. Since the transport speed V of the paper 41 is usually constant, the transport speed V
The length from the front end to the rear end can be calculated.

Thus, in this case, the length L _{1 of the first} sheet 41 is calculated.

Next, proceeding to step S6, the CPU 21
It is determined whether or not the current process is the first job.
In this case, since this is the first job, step S8
The CPU 21 determines whether the value of the variable CT is equal to the number of sheets 41 to be printed (conveyed) in one job. For example, in the current job,
Assuming that the number of sheets 41 to be printed is six, the current value of the variable CT is 1, which means that the value of the variable CT is not equal to the number of sheets 41 conveyed in one job. become.

Therefore, in this case, returning to step S2,
In step S2, the process waits again until the leading edge of the next sheet 41 is detected. When the leading end of the paper 41 is detected, the time t1 is stored again. Further, in step S3, the process waits until the trailing edge of the sheet 41 is detected, and when it is detected, the time t2 is stored.

In step S4, the value of the variable CT is incremented by 1, and in this case, CT = 2.

In step S5, the CPU 21 calculates the length data L2 of the _second sheet 41 by the above-mentioned formula and stores it.

Next, in step S6, it is determined whether the current processing is the first job. Since the current process is the first job, the process proceeds to step S8 again, and it is determined whether the value of the variable CT is equal to the number of sheets (six) printed in one job. In this case, the value of the variable CT has not yet reached 6, so again
Returning to step S2, the subsequent processing is repeatedly executed.

As described above, when printing is performed on the six sheets of paper 41, the value of the variable CT becomes 6, and at this time, YES is determined in step S8, and the process proceeds to step S9. In step S9, the CPU 21 determines whether all jobs have been completed. In this case, since all jobs have not been completed yet, step S is executed again.
The process returns to 1 and the subsequent processes are repeatedly executed.

Hereinafter, in the second job, the first job
The same processing as in the case of the second job is executed.

However, in the second and subsequent processing,
In step S6, it is determined that the job is not the first job.
Therefore, the process proceeds to step S7, and the process in step S5
Calculated and stored CT-th length data of the current job
L_CTIs the CT-th length data L of the previous job_CT-1
Is compared to The difference between them (L_CT-L_CT-1)
It is determined whether it is within the set reference range.
You. Previous length data L _CT-1And the current length data L_CT
The difference between is the standard range if the paper 41 is not layered.
Will be within. Therefore, in this case, step S8
To the value of the variable CT and the number of prints in one job
Is determined to be equal to or not.
Returning to S2, the subsequent processing is repeatedly executed.

On the other hand, when double feeding occurs, the difference between the length data becomes larger than within the reference range. That is, for example, as shown in FIG. 5, when a sheet 41B to be subsequently conveyed is conveyed while being superposed on a part of the sheet 41A, the paper detection sensor 32 detects the next sheet from the leading end of the sheet 41A. The length to the rear end of the sheet 41B is detected. This length is longer than the length from the leading end to the trailing end of one sheet 41A (the absolute value of (L _CT -L _CT-1 ) becomes larger than the reference range). Therefore, in this case, the process proceeds to step S10, and the CPU 21 determines that a double feed has been detected and executes a process corresponding to the double feed. Specifically, the CPU 21 controls the motor driver 24 to temporarily suspend the conveyance. Then, the personal computer 1 is notified that the double feed has been detected. When the personal computer 1 receives the notification, the personal computer 1 displays the notification on a display unit included in the output unit 127. Thereby, the user can know that the multi-feed has occurred, and once reset the job by removing the paper 41 or the like. Then, the processing of the next job is started again.

FIG. 6 shows an example in which a double feed is detected by detecting the length in this manner. In the case of this example, one job is composed of six sheets. In each job, the length of the first and second sheets 41 is 200 mm, and the length of the third sheet 41 is 220
mm, the length of the fourth sheet is 250 mm, the length of the fifth sheet is 200 mm, and the length of the last sixth sheet 41 is 220 mm.

If no double feed has occurred, as shown in Job 1 and Job 2, the length of each sheet 41 detected in each job is the same as the previous time. That is, in this example, even in the second job, 6
The sheets 41 are 200 mm, 200 mm, 220 mm, 25
It is sequentially detected at lengths of 0 mm, 200 mm, and 220 mm.

On the other hand, in the third job, the length of the first sheet 41 was 200 mm.
The length of the second sheet is 300 mm this time, while the length of the previous second sheet is 200 mm. As described above, when a length different from the previous length is detected, it is determined that the double feed is performed.

When the detected (measured) length of the paper 41 is compared with an absolute reference value (the actual length of the paper 41),
Variations occur depending on the state of the apparatus and the detection accuracy of the paper detection sensor 32. Therefore, it is difficult to accurately detect double feed.

On the other hand, as shown in this example, the paper 41
Is not based on the true length, but based on the previous length. For example, if the paper detection sensor 32 tends to detect a length longer than the actual length, the previous Similarly, this tendency appears. Therefore, the paper detection sensor 3
The double feed can be detected without being affected by the measurement accuracy of the second feed.

In the above description, the length of the paper 41 is detected. However, the present invention can be applied to the case of detecting the thickness. FIG. 7 shows a configuration example in this case.

That is, in the example of FIG. 7, instead of the paper detection sensor 32, a paper thickness detection sensor 51 detects the thickness of the paper 41, and the detection result is transmitted to the CPU 21 via the input / output interface 23. It is configured to notify.

The other structure is the same as in FIG.

The paper thickness detection sensor 51 irradiates light toward the paper 41 to be conveyed, and detects the thickness of the paper from the light receiving position of the reflected light. That is, as shown in FIG.
Compared to the case where only one sheet 41 is correctly conveyed, as shown in FIG.
When B is conveyed in an overlapping manner (when the paper 41 becomes thicker), the light receiving position of the reflected light changes. The paper thickness detection sensor 51 is
A signal corresponding to the light receiving position of the reflected light is output to the CPU 21 via the input / output interface 23.

FIG. 9 shows a configuration example of the paper thickness detection sensor 51. In this example, the light generated by the LED 52 is applied to the paper 41, and the irregularly reflected light is applied to the slit 53.
(Position Sensitive Detector) sensor 5
4 is incident.

As shown in the figure, the light receiving position of the reflected light in the PSD sensor 54 is such that when the thickness of the paper 41 is thick (when the light reflecting surface of the paper 41 is close to the LED 52),
On the contrary, when the sheet 41 is thin (the light reflecting surface of the sheet 41 is far from the LED 52), the position is higher in the figure. Therefore, the thickness of the paper 41 can be detected from the light receiving position of the PSD sensor 54.

Next, the processing of the system of FIG. 7 will be described with reference to the flowchart of FIG.

First, in step S21, the CPU 21
Initializes the value of the variable CT to 0. In step S22, the CPU 21 determines from the output of the paper thickness detection sensor 51
It waits until it is determined that the paper 41 has been detected. Since the level of the output signal of the paper thickness detection sensor 51 changes depending on whether or not the paper 41 is present, it is possible to determine whether or not the leading end of the paper 41 has been detected from this change.

When the leading end of the paper 41 is detected, the process proceeds to step S23, where the CPU 21 acquires data relating to the thickness of the paper 41 (data relating to the light receiving position).

Next, the process proceeds to step S24, where the CPU 21
Determines whether the paper 41 has run out, and if not, returns to step S23 and again
1. Obtain data relating to the thickness of 1.

The above processing is performed in step S24.
The process is repeatedly performed until the trailing edge of the paper 41 is detected.

If it is determined in step S24 that the trailing edge of the paper 41 has been detected, the process proceeds to step S25, where the CPU 21 increments the value of the variable CT by one. Then, the sheet 41 detected a plurality of times in step S23
The average value is calculated from the data relating to the thickness of the. Then, the average value is stored in the memory 22 as the thickness of the one sheet 41.

Next, the process proceeds to step S26, where the CPU 21
Determines whether the job is the first job. If the job is the first job, the process advances to step S28 to determine whether the value of the variable CT is equal to the number of prints performed in the one job. Is determined. If it is determined that the value of the variable CT is not equal to the number of prints performed in one job, the process returns to step S22, and the subsequent processes are repeatedly executed.

As described above, the thickness (average value) of each sheet of the first job is stored in the memory 22.

When the processing of the first job is completed, the process proceeds from step S28 to step S29, and it is determined whether or not processing of all jobs has been completed. If all the jobs have not been processed, the process returns to step S21, and the subsequent processes are repeatedly executed.

In the second and subsequent jobs, the process proceeds from step S26 to step S27, and in step S25, the thickness T _CT of the n-th sheet 41 of the current job is _calculated .
It is determined whether the difference from the thickness T _CT-1 of the n-th sheet 41 of the previous job is within the reference range. If the difference between the two is within the reference range, it is determined that double feeding is not occurring, and the process proceeds to step S28, and the subsequent processing is executed.

If it is determined in step S27 that the difference between the thicknesses of the two sheets is not within the reference range, the process proceeds to step S30, where the CPU 21 executes a multi-feed process. That is, the personal computer 1 is notified that the conveyance of the paper 41 has been temporarily interrupted and that multifeed has occurred.

FIG. 11 shows an example of a numerical value at which a double feed is detected by detecting the thickness. In this example, in the first job, the thickness of six sheets 41 is 0.5 mm,
While 0.5 mm, 0.6 mm, 0.5 mm, 0.8 mm, and 0.5 mm are sequentially detected in this order, in the second job, the first and second sheets are , Respectively.
Although it is detected as 5 mm, the thickness of the third sheet 41 is detected as 1.0 mm. This 1.0 mm is 0.6 mm which is the thickness of the third sheet in the previous job.
Is very different. Therefore, in this case, it is determined that double feed has occurred.

FIG. 12 shows a configuration example of a printing system in the case where the paper 41 is detected by ultrasonic waves. In this example, the ultrasonic transmitter 61 generates ultrasonic waves, and the ultrasonic waves are received by the ultrasonic receiver 62 via the paper path.

The control block 71 is supplied with the clock generated by the oscillator 72.
Various operations are executed in synchronization with this clock.

The control block 71 controls the oscillation amplifier 73, drives the oscillation transmitter 73 to drive the ultrasonic transmitter 61,
Generate ultrasonic waves.

The output of the oscillation amplifier 73 is used for monitoring.
Through the AD converter 74, the filter 9 of the control block 71
1 has been entered. The filter 91 removes a noise component (high-frequency component) of the input signal and outputs the signal to the oscillation peak detection unit 92. The oscillation peak detecting section 92 detects the peak value from the input signal and outputs the detected peak value to the processing section 93.

[0093] The amplifier 74 amplifies the output of the ultrasonic receiver 62 and outputs it to the level determination unit 75. Level judgment unit 7
5 determines the level of the signal input from the amplifier 74, determines that the paper 41 does not exist when the level is higher than the reference value, and determines that the paper 41 exists when the level is lower than the reference value. judge. Level judgment unit 75
Outputs a detection signal (paper presence signal) to the processing unit 93 when it is determined that the paper 41 is present. At this time, the level determination unit 75 turns off the analog switch 79 and turns on the analog switch 78, and inputs the output of the amplifier 74 to the AD converter 80.

On the other hand, when it is determined that the paper 41 does not exist, the level determining section 75 turns off the analog switch 78 and turns on the analog switch 79, and outputs the output of the amplifier 74 to the resistor 76 and the resistor 76. After the voltage is divided (attenuated) at 77, it is input to the AD converter 80.

The filter 95 removes a noise component (high-frequency component) of the signal input from the AD converter 80 and outputs the signal to the reception peak detector 96. The reception peak detection unit 96 detects the peak value of the signal input from the filter 95 and outputs the signal to the processing unit 93.

The loop counter 94 counts the clock supplied from the oscillator 72 and outputs the count value to the processing section 93.

The motor driver 24 is controlled by the processing section 93 and drives the motor 25.

When the frequency of the signal output from the oscillation amplifier 73 to the ultrasonic transmitter 61 is f, the frequency of the clock output from the oscillator 72 is, for example, 360f. The AD converters 74 and 80 perform sampling at the frequency of 360f, and the loop counter 94 counts the clock of the frequency of 360f.

Next, the processing of the system of FIG. 12 will be described with reference to the flowchart of FIG.

In step S41, the CPU 21 initializes a variable CT to 0. In step S42, the CP
U21 monitors the output of the processing unit 93 and waits until the paper 41 is detected.

That is, when the start of processing is instructed from the personal computer 1, the CPU 21 controls the control block 71 to supply a clock to the oscillation amplifier 73. The oscillation amplifier 73 drives the ultrasonic transmitter 61 with a signal of the frequency f to generate an ultrasonic wave. Ultrasonic receiver 6
2 receives the ultrasonic wave generated by the ultrasonic transmitter 61 and supplies the received signal to the amplifier 74. The amplifier 74 amplifies the input signal and outputs the amplified signal to the level determination unit 75.

Assuming that the drive signal supplied from the oscillation amplifier 73 to the ultrasonic transmitter 61 is, for example, the signal shown in FIG. 14A, the signal received by the ultrasonic receiver 62 is shown in FIGS. 14D.

FIG. 14B shows a state in which the paper 41 is placed on the transmission path of the ultrasonic wave.
Represents a received signal in the case where there is no. On the other hand, FIGS. 14C and 14D show that the paper 4
1 shows an example of a received signal when 1 exists. As is clear from comparison of these figures, the level of the received signal is higher when the paper 41 is not present than when the paper 41 is present.

Therefore, the level judging section 75 includes the amplifier 74
The received signal level is compared with a predetermined reference value. If the received signal level is higher than the reference value, it is determined that the paper 41 does not exist. Is determined to exist. This determination result is notified to the CPU 21 via the processing unit 93.

If it is determined in step S42 that the paper 41 has been detected, the process proceeds to step S43, in which the CPU 41
21 detects the peak value of the oscillation signal (the signal shown in FIG. 14A) output by the oscillation peak detection unit 92 and the peak of the reception signal (the signal shown in FIGS. 14B to D) output by the reception peak detection unit 96 Then, the phase of the received signal is detected from those signals.

[0106] That is, the oscillation peak detecting unit 92, the oscillation amplifier 73 outputs, upon detecting the peak value P _A of the signal shown in FIG. 14A, and outputs the detection signal, the CPU21 via the processing unit 93. Further, CPU 21 at the timing of the peak value P _A is detected once to reset the count value of the loop counter 94. Thereafter, loop counter 94 immediately executes the operation of counting clocks.

When the paper 41 is not present in the transport path, the level determination section 75 turns off the analog switch 78 and turns on the analog switch 79. As a result, the amplifier 7
The high-level received signal output from 4 is connected to the resistor 76
And 77, and after being attenuated to a predetermined level,
The signal is input to the AD converter 80 via the analog switch 79.

On the other hand, when the paper 41 is present, the analog switch 79 is turned off and the analog switch 78 is turned on. As a result, the received signal output from the amplifier 74 is input to the AD converter 80 via the analog switch 78 (without attenuation). By setting the values of the resistors 76 and 77 to predetermined values, the level of the received signal input via the analog switch 78 when the paper 41 is present and the analog switch when the paper 41 is not present The level of the signal input via 79 can be substantially the same level. As a result, the AD converter 80 can efficiently perform the AD conversion processing in the same dynamic range regardless of the presence or absence of the paper 41.

The AD converter 80 determines the level of the received signal.
A / D conversion and a reception peak detection unit 96 via a filter 95
To enter. The reception peak detector 96 detects a peak of the reception signal. Specifically, for example, the peak value P _{B of} the received signal shown in FIG. 14B, the peak value P _{C of} the received signal shown in FIG. 14C, or the peak value P _{D of the} received signal shown in FIG. Is detected.

When a peak value is detected by the reception peak detection unit 96, the detection signal is sent to the CP via the processing unit 93.
It is supplied to U21. The CPU 21 reads the count value of the loop counter 94 at the timing when the detection signal is input.

The count value of the loop counter 94 corresponds to the phases of the transmission wave (FIG. 14A) and the reception wave (FIG. 14B, C, D).

When the paper 41 does not exist, the transmission wave (FIG. 1)
The difference (phase difference) θ ₁ between the timing at which the peak value P _{A of} 4A) is detected and the timing at which the peak value P _{B of the} received wave (FIG. 14B) is detected is a substantially constant value.

When the number of sheets 41 on the transport path is one,
The phase difference between the received signal and the transmitted signal is substantially constant. FIG. 14 shows this phase difference as θ ₂ . In other words, if the paper 41 is one, the timing of the peak value P _C, is P _D generated by the received signal about a theta _2, within the range of ± [Delta] Z.

[0114] In contrast, if the sheet 41 is multi-fed, the peak value P _C, the generation timing of P _D is not within this range.

Therefore, the phase difference θ between the received wave and the transmitted wave
Thus, double feed can be detected.

Therefore, in step S43, the CPU
21 acquires the phase of the received signal (the phase difference between the received signal and the transmitted signal).

The CPU 21 repeatedly executes the data acquisition process in step S43 until it is determined in step S44 that the sheet 41 is no longer present. As described above, the presence or absence of the paper 41 can be detected from the level of the received signal.

If it is determined that the paper 41 does not exist,
Proceeding from step S44 to step S45, the CPU 21
Calculates the average value of the phase difference θ acquired in step S43 by incrementing the value of the variable CT initialized in step S41 by one. Then, the average value is supplied to and stored in the memory 22 as the phase difference of the one sheet.

In step S46, the CPU 21 determines whether or not the job is the first job. If the job is the first job, the process proceeds to step S48, where the value of the variable CT is set to one job. It is determined whether or not the number is equal to the number of prints to be performed.
The subsequent processing is repeatedly executed.

If it is determined in step S48 that the value of the variable CT is equal to the number of prints performed in one job, the process proceeds to step S49, and the CPU 21 determines whether all jobs have been completed. I do. If all the jobs have not been completed yet, the process returns to step S41,
Subsequent processes are repeatedly executed.

In the second and subsequent jobs, in step S47, the difference between the phase difference θ _CT of the current job and the phase difference θ _CT-1 of the previous job is determined based on a predetermined reference. It is determined whether it is within the range. As described above, when no double feed has occurred, the current phase difference θ _CT is substantially equal to the previous phase difference θ _CT-1 . In this case, step S
From 48, the process returns to step S42, and the subsequent processes are repeatedly executed.

On the other hand, if it is determined that the difference between the two phase differences is not within the range of the predetermined reference, it is determined that the multi-feed has occurred, and the flow advances to step S50 to execute the multi-feed process.

In the above description, the present invention has been described by taking the case of controlling a printing machine as an example. However, the present invention can also be applied to the case of conveying a copier, a scanner, and other paper sheets. It is.

The series of processes described above can be executed by hardware, but can also be executed by software. When a series of processing is executed by software, a program constituting the software executes various functions by installing a computer incorporated in dedicated hardware or various programs. For example, it is installed from a network or a recording medium into a general-purpose personal computer or the like.

This recording medium is, as shown in FIG.
A magnetic disk 141 (including a floppy disk) on which the program is recorded and an optical disk 14 which are distributed to provide the user with the program separately from the apparatus main body
2 (CD-ROM (Compact Disk-Read Only Memory), DVD (Digi
tal Versatile Disk), magneto-optical disk 143
(Including an MD (Mini-Disk)) or a package medium including a semiconductor memory 144 and the like.
2 and a hard disk included in the storage unit 128.

In this specification, the step of describing a program recorded on a recording medium may be performed not only in chronological order according to the described order but also in chronological order. This also includes processing executed in parallel or individually.

[0127]

As described above, according to the present invention, the detection result of the current job is compared with the detection result of the previous job,
Based on the comparison result, multi-feeding of paper sheets is detected, so even when conveying mixed paper,
Double feed can be detected simply and reliably.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a printing system to which the present invention has been applied.

FIG. 2 is a block diagram showing a configuration of the printing press shown in FIG.

FIG. 3 is a block diagram illustrating a configuration of the personal computer of FIG.

FIG. 4 is a flowchart illustrating a detection process based on a sheet length of the system of FIG. 1;

FIG. 5 is a diagram illustrating a multi-feed state in the system of FIG. 2;

FIG. 6 is a diagram illustrating an example of double feed detected by the process of FIG. 4;

FIG. 7 is a block diagram illustrating another configuration of the printing press in FIG. 1;

FIG. 8 is a diagram showing a double feeding state in the apparatus of FIG. 7;

FIG. 9 is a diagram illustrating a configuration of a paper thickness detection sensor of FIG. 7;

FIG. 10 is a flowchart illustrating a detection process based on a sheet thickness of the apparatus of FIG. 7;

FIG. 11 is a diagram illustrating an example of double feed detected by the process of FIG. 10;

FIG. 12 is a block diagram illustrating another configuration example of the printing press in FIG. 1;

FIG. 13 is a flowchart illustrating a process of the apparatus in FIG. 12;

FIG. 14 is a diagram illustrating the principle of double feed detection using ultrasonic waves.

[Explanation of symbols]

1 personal computer, 2 printing press, 21
CPU, 22 memories, 23 input / output interfaces, 24 motor drivers, 25 motors, 26
Belt, 27, 28 transport roller, 29 belt,
30, 31 conveyance roller, 32 paper detection sensor, 4
1 paper

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomohiro Inoue 801 Shimogyo-ku, Shimogyo-ku, Higashi-iri, Higashi-iri, Minami-Fudo-do, OMRON Corporation F-term (reference) 3F048 AA05 AB01 BA13 BB09 CA02 CA03 DC14 EB22

Claims (6)

[Claims] 1. A sheet detecting means for detecting a characteristic of a conveyed sheet, and a result detected by the sheet detecting means for each job as a unit for repeatedly conveying a plurality of sheets is stored. A comparing unit that compares a detection result of the current job detected by the paper sheet detecting unit with a detection result of a previous job stored in the storing unit; A multi-feed detecting device comprising: a multi-feed detecting unit configured to detect the multi-feed of the paper sheets based on a result. 2. The sheet multi-feed detecting device according to claim 1, wherein the sheet detecting means detects a length of the sheet. 3. The sheet multi-feed detecting device according to claim 1, wherein the sheet detecting means detects a thickness of the sheet. 4. The sheet multi-feed detecting apparatus according to claim 1, wherein the sheet detecting means detects at least one of a level and a phase of an ultrasonic wave transmitted through the sheet. . 5. A result detected by the sheet detecting step of detecting a characteristic of a sheet to be conveyed, and the sheet detecting step for each job as a unit for repeatedly conveying a plurality of sheets. A comparing step of comparing the detection result of the current job detected by the processing of the paper sheet detecting step with the detection result of the previous job stored by the processing of the storing step. A double feed detecting step of detecting a double feed of the paper sheets based on a comparison result obtained by the processing of the comparing step. 6. An acquisition step for acquiring a detection result of the characteristic of the conveyed paper sheets, and a result obtained by the processing of the acquisition step for each job as a unit for repeatedly transporting a plurality of paper sheets is stored. A storage step; a comparison step of comparing the detection result of the current job acquired by the processing of the acquisition step with the detection result of the previous job stored by the processing of the storage step; and the processing of the comparison step And a multi-feed detecting step of detecting the multi-feed of the paper sheets based on the comparison result by the computer.