JPH01252440A - Superposed feed judgement controller - Google Patents

Abstract

PURPOSE:To achieve cost cut and improve the superposed feed precision by comparing the driving electric current obtained by a driving electric current detecting means for a paper feed motor and judging the superposed feed of a recording paper on the basis of the comparison output. CONSTITUTION:A resistor 22 is connected in an electric current passage for a paper feeding motor 21, and a driving electric current corresponding to the drive current supplied into the motor 21 is obtained at a connection point P. The driving voltage is amplified, and converted to a digital signal, which is transmitted to a superposed feed judging means 25 and compared with a standard value. When the value is larger than a standard value, the superposed feed is judged, and a driving clutch control means 27 is controlled on the basis of the judgement output, and a driving clutch 16 is opened. Therefore, only the revolution of a paper feeding roller 14b on the upstream side is stopped, and only a recording paper 5 on the 7 side among the superposed recording paper 5 is supplied, and the recording paper 5 on the upper side is stopped. When the superposed state is detected, the fact is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a double feed determination control device suitable for application to an electrophotographic copying machine using ordinary recording paper or the like.

[Prior Art] In electronic copying machines that use regular recording paper, the recording paper may be fed in duplicate due to differences in paper thickness or static electricity charging.

If the recording paper is fed multiple times, the toner image will not be completely transferred when the multiple feeding is completed, so the transfer process will not be performed accurately and the copy quality will deteriorate.

Therefore, this double feeding state has conventionally been detected, and when the recording paper is double fed, the copying operation is prohibited or a message to that effect is displayed.

A double feed state may be detected as follows.

That is, a double feed detection means is provided on either one of the pair of paper feed rollers that are provided so as to be able to sandwich the recording paper. For example, a minute displacement detection means is attached to the rotating shaft of the upper paper feed roller, and single sheet feeding and multiple sheet feeding are detected based on the displacement of the rotating shaft.

Depending on the detection output, the rotation of the paper feed roller is stopped or a display to that effect is displayed.

[Problems to be Solved by the Invention] By the way, such means for determining double feeding of recording paper based on the displacement of the rotation axis has the following drawbacks.

First, the configuration becomes complicated.

That is, it is necessary to attach the above-mentioned displacement detection means to the rotating shaft of the paper feed roller, and an increase in the number of parts also results in an increase in cost.

Second, the accuracy of double feeding determination is not very good.

The reason is that the displacement in the diametrical direction of the rotating shaft when double feeding is performed is extremely small, and even if a minute displacement detection means is used, the displacement cannot always be accurately detected.

As a result, there was a problem that the transmission determination accuracy could not be improved.

Therefore, the present invention solves these conventional problems, and provides a double-feed detection method that enables accurate determination of double-feeding of recording paper and achieves appropriate control in response. This paper proposes a control device.

[Means for Solving the Problems] In order to solve the above-mentioned problems, a drive current detection means for the paper feed motor, a drive current obtained from this detection means is compared with a reference value, and the comparison - output ζ is calculated. The present invention is characterized in that it has a double feed determination means for determining electric feeding of the recording paper based on the determination output, and the paper feed roller and the like are controlled based on the determination output.

[Operation] In this configuration, the drive current supplied to the paper feed motor 21 and the load applied to the paper feed motor 21 have a corresponding relationship. The load applied to the paper feed motor 21 corresponds to the number of multi-fed recording sheets 5 fed.

Therefore, double feeding of the recording paper 5 can be determined by detecting the drive current.

The drive current for the paper feed motor 21 is once converted into a voltage value, the drive voltage after conversion is compared with a reference value, and it is determined whether the recording paper 5 is being electrically fed based on the comparison output.

In this example, a microcomputer (CPU) is used as the determination means 25, and the average value output obtained during a predetermined period is compared with a reference value.

If it is larger than the standard value, it is a heavy load and the recording paper 5
This means that the items were shipped in duplicate.

Based on the determination output, in this example, the rotational state of the second paper feed roller 14 is controlled as desired, and the separation process of the recording paper 5 is performed.

At the same time as the peeling process, post-processing indications such as removal of double fed sheets may be performed.

[Example] Next, an example of the double feed determination control device according to the present invention will be described in detail with reference to FIG. explain.

FIG. 1 is a schematic diagram showing an electrophotographic copying machine 10 to which the present invention is applied. The surface of a photosensitive drum 1 is charged to a predetermined potential, and is exposed to light in accordance with image information. The exposed photosensitive drum 1 is rotated roughly, so that the toner supplied from the developer N2 is layered several times, and a predetermined optical image is completely developed.

The developed toner particles are transferred onto the recording paper 5 by rough rotation. 3 is its transfer pole, and 4 is its separation pole.

The transferred and separated recording paper 5 is fed to a fixing device (not shown), subjected to fixing processing, and then discharged outside the machine.

Recording paper 5 placed on document tray 7 is fed onto paper feed path 12 via first paper feed roller 11 .

Reference numeral 21 indicates a paper feed motor for driving the same.

A paper detection sensor 13 is disposed in the middle of the feeding path of the recording paper 5, and when the recording paper 5 kicks this sensor, the leading edge of the recording paper can be detected.

The recording paper 5 is roughly timed to be fed with respect to the rotation of the photosensitive drum by the second paper feeding roller 14, and then
The paper is fed to the photosensitive drum 11 side.

As shown, the second paper feed roller 14 is comprised of a pair of upper and lower paper feed rollers 14a, 14b, each of which is coupled to a paper feed motor 18 via a drive clutch 15,16.

Incidentally, the drive current or drive voltage of the paper feed motor 21 corresponds to the load applied to the paper feed motor 21.

Since this load corresponds to the number of double feeds of the fed recording sheets 5, it is possible to determine whether or not double feeding of the recording sheets 5 is occurring by detecting the large jaggedness of the load applied to the paper feed motor 21.

For this reason, in the present invention, the presence or absence of double feeding of the recording paper 5 is determined by detecting the drive current of the paper feed motor 21 or the drive voltage obtained by converting this into voltage.

FIG. 2 is a block diagram showing an example of a double feed determination control device according to the present invention suitable for use in such a copying machine 10.

Reference numeral 21 indicates a drive motor for driving the first paper feed roller 11, that is, a paper feed motor, as described above.

A resistor 22 functioning as a current-voltage conversion means is connected in the current path for the paper feed motor 21, so that a drive voltage corresponding to the drive current supplied to the paper feed motor 21 is obtained at the connection point P.

This driving voltage is amplified to a predetermined level by an operational amplifier 23, and then supplied to an A/D converter 24, where it is converted into a digital number 43. The digital signal is supplied to the double feed determination means 25, and it is determined whether the recording sheets 5 that have been completely fed are double fed.

In this example, a microcomputer (CPU) is used as the double-feed determining means 25, and in the double-feed determining means 25, the digital signal is compared with a reference value, and the recorded paper 5 fed is determined depending on the magnitude of the digital signal. double feeding is determined.

Specifically, when the edge is smaller than the reference value, it is assumed that one sheet is being fed, the motor drive circuit 26 is driven normally, and the drive clutch control means 27 is controlled to be inoperative.

As a result, both drive clutches 15 and 16 operate normally, and as shown in FIG.
4b rotates and paper feeding is performed normally.

On the other hand, if the value is greater than the reference value, this state is determined to be double feeding, and the drive clutch control means 2
7 is controlled. As a result, the upper paper feed roller 14
The drive clutch 16 provided in connection with b serves as an oven.

In this way, as shown in FIG.
Since rotation of only b is stopped, only the lower recording paper 5 among the double-fed recording papers 5 is fed, and the upper recording paper 5 remains stopped.

Note that the motor drive circuit 26 is controlled to be in an operating state so that the lower paper feed roller 14a continues to rotate even in the double feeding state.

If a double feed condition is detected, a message to that effect is displayed. For example, a message such as ``Please remove the paper.'' may be displayed.

Then, the load applied to the first paper feed roller 11 is a single value proportional to the number of multi-fed sheets of recording paper 5 (a value corresponding to the basis weight of the recording paper).
In reality, there is considerable variation in whether it is ideal to take this.

In FIG. 3, the white bar graph indicates the variation in the driving voltage after feeding one sheet of recording paper 5 weighing 155 kg. Similarly, the bar graph indicated by diagonal lines slanting to the left indicates the variation in the drive voltage when one sheet of recording paper 5 having a basis weight of 70 kg is fed.

Since the drive voltage varies when a single sheet is fed, the drive voltage when two or more sheets are fed also varies proportionally. The bar graph indicated by diagonal lines slanting to the right represents the variation in the driving voltage when two sheets of recording paper 5 having a basis weight of 55 kg are fed in duplicate. Similarly, the bar graph indicated by double diagonal lines indicates the variation in the drive voltage when two sheets of recording paper 5 having a basis weight of 70 kg are fed in duplicate.

One of the causes of the variation is eccentricity of the first paper feed roller 11. This is because if there is eccentricity, the load applied to the first paper feed roller 11 will also vary periodically.

In order to eliminate this periodic fluctuation, the average value of the drive voltage obtained during a period that is an integral multiple of the rotation period may be used as the detection data. The values of straight lines La and Lc are the average driving voltage for recording paper with a basis weight of 55 kg, and the values of straight lines Lb and Ld are the average driving voltage values when the basis weight is 70 kg.

Therefore, by setting an intermediate value between the straight lines Lb and Lc as the reference value, it is possible to determine whether there is double feeding regardless of the basis weight.

Furthermore, as is well known, when the motor is turned on, an inrush current flows.
Since residual current is generated when the motor is off, the drive current fluctuates significantly in both of these cases.

Therefore, the data sampling time required to actually determine double feeding is selected within a stable state excluding the motor on/off timing periods.

The double feed determination means 25 described above determines whether or not there is double feed using a double feed determination control routine as shown in FIG.

Next, an example of the double feed determination control program 30 will be described with reference to FIG. 6.

When the control program 30 starts, it is first checked whether it is the data sampling start period (step 31).

As mentioned above, this sampling period refers to any period that does not include when the motor is on or off.

When the sampling period for the weight data arrives, the weight ♂1
The constant data is read and the sum of each is taken (steps 32 and 33).

The period used as measurement data is the first paper feed roller 11.
The rotation period is an integer multiple of .

Next, it is checked whether the weight data sampling period has ended or not, and if it has ended, the average value is calculated based on the sum of the weight measurement data (steps 34 and 35).
). Thereafter, it is compared whether it is larger than the reference value VREF (steps 36 and 37).

Therefore, first, it is checked whether one sheet of recording paper 5 with a basis weight of 55 kg has been fed, and if so, the recording paper 5 with a basis weight of 55 kg is checked.
The transfer current, separation current, and fixing heater drive current corresponding to kg are set (step 36.40).

At this time, the paper feed motor 18 can be controlled to the driving state (step 42). The same applies to double feeding.

When the basis weight is 70 kg, the transfer current, separation current, and fixing heater drive current for the 70 kg basis weight are each set (step 37.41).

If this is not the case, the double feed flag is set, which controls the control means 27 to perform double feed prevention processing (step 38).

In this example, in addition to the above-described processing, it is determined which weight of recording paper has been multi-fed, and the transfer current, separation current, and fixing heater drive current are set according to the weight (step 39).゜40.41).

In the above description, when the paper thickness of the recording paper differs, the transfer voltage etc. that can be applied to the transfer poles are controlled accordingly. This is because when the basis weight becomes heavy, that is, when thick recording paper is used, if the transfer voltage is low, it becomes difficult to transfer the toner image onto the recording paper, and the copy quality deteriorates.

[Effects of the Invention] As explained above, according to the present invention, attention is paid to the fact that the drive current supplied to the paper feed motor is proportional to the number of sheets of recording paper fed, and the drive current for this paper feed motor is used as a reference. Double feeding of the fed recording paper is determined by comparing the values.

Although the drive current for the paper feed motor varies to some extent due to changes in load, by taking the average value of each, it is possible to determine whether there is a double feeding state.

In particular, since there is a large difference in the average value between single sheet feeding and multiple sheet feeding, it is necessary to reliably determine the presence or absence of electrical transmission.

Therefore, it is possible to provide a highly accurate double feed determination control device that can reduce costs compared to the conventional method.

From the above, the double feed determination control device according to the present invention has the following features:
It is extremely suitable for application to an electrophotographic copying machine that uses ordinary recording paper as described above.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of an electrophotographic copying machine using ordinary recording paper to which the present invention can be applied, and FIG. 2 is a block diagram showing an example of a double feed determination control device according to the present invention.
FIG. 3 is a diagram showing the relationship between drive voltage and frequency of occurrence, FIGS. 4 and 5 are explanatory diagrams showing double feed processing, and FIG. 6 is a flowchart showing an example of a double feed determination control program. 1...Photosensitive drum 2...Developer 5...Recording paper 11...First paper feed roller 14...Second paper feed roller 20...Double feed determination control device 18.21. ...Paper feed motor 25...Electrical transmission determination means 27...Drive clutch control means Fig. 2 Fig. 3 Fig. 4 Fig. 5

Claims (1)

[Claims] (1) It has a drive current detection means for the paper feed motor, and a double feed determination means that compares the drive current obtained from this detection means with a reference value and determines double feed of recording paper based on the comparison output. A double feed determination control device characterized in that a paper feed roller is controlled based on this determination output.