JPH03192050A - Double feed detecting device for paper form - Google Patents

Abstract

PURPOSE:To correctly judge a double feed state without being influenced by the paper form thickness, etc. by judging double feed by means of the thickness of the n-th paper form and the value which is obtained by multiplying the difference of the data in the case where no paper form exist by the set value and comparing the thickness of the n+1-the paper form with the difference of the data where no paper form exists. CONSTITUTION:When the data (an) and an+1 are compared with each other for the cases where the number of paper form is one and two, the output value (an) is multiplied by a set value X, and Xan is compared with the data in case of an+1. In this case, a set value X 1.5 is used. In comparison with the case where no paper form exists the output value in case of one sheet of paper form is (an), and the output value in case of two sheets of paper form differs by about 2an, and when the state where no paper form exists is set as standard, the ratio of output values between in the cases where the number of paper sheets is one and two becomes twice. Accordingly, double feed is judged by using the intermediate value 1.5 of the ratio between the cases where paper form exists and does not exist, as set value. Accordingly, even if noise is mixed in the thickness data of the paper form, if the data is within a range of 1.5 times of (an), there is no change for allowing generation judgement.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for detecting double feeding of paper in a paper conveyance path in an apparatus for creating recording paper using cut paper, and in particular, The present invention relates to a device that outputs the thickness of sheets passing through a predetermined position on a sheet conveyance path as an electrical signal, thereby making it possible to detect double feeding of arbitrary sheets of paper that are continuously conveyed.

(Prior Art) In devices that use cut paper, such as printers and electronic copying machines, paper is fed out one sheet at a time from a paper storage device such as a paper tray or paper feed cassette using a paper sorting mechanism.
It is supplied to the printing area to perform printing and image transfer to create recording paper.

In the above-mentioned image forming apparatus, it is necessary to feed sheets one by one. For example, when two or more sheets are fed overlappingly, it is difficult to accurately convey the sheets. This may cause a paper jam in the paper transport path, or the transferred image may not be formed at the specified position on the paper, resulting in misalignment of the image and the creation of defective copies. There's a problem.

Therefore, in conventional image forming apparatuses, a paper double-feed detection means is provided in the paper transport path between the paper feeder and the image forming position, and a paper double-feed detection means is provided to detect when two or more sheets of paper are transported in an overlapping state. In such cases, countermeasures such as removing the paper are taken.

As a means for detecting the multi-feed state of paper, which is placed in the paper conveyance path as described above, for example, a transmission type photo sensor is used to detect whether there is one sheet of paper or multiple sheets of paper. There are methods that detect differences in the amount of transmitted light. In addition, a method is used in which a swinging arm is placed at a position where it is swung by the passing paper, and the swinging arm detects that the angle at which the arm member is swung differs depending on the thickness of the paper. There is also.

In the double-feed state detection method described above, when a photo sensor is used, in the case of tracing paper or plain paper, it is relatively easy to distinguish between one sheet and two or more sheets. For comparatively thick paper, there are problems such as difficulty in determining double feeding because the paper does not transmit much light.

Furthermore, when detecting the thickness of paper, if the output from the detection means shows a linear change as shown in graphs A and 8 in Figure 5, the detected value will change. Judgment will be made better. However, as shown in C in the same figure, the detection information when using the photo sensor has a very large difference between when there is paper and when there is no paper, and the difference between when there is one sheet of paper and when there are two sheets of paper. However, it will be very small.

Therefore, in a device that passes light through the paper and determines whether the paper is double fed based on the amount of transmitted light, the thickness of the paper itself is a major factor.
In addition, there are many difficulties in actual use, such as the difficulty in determining the amount of transmitted light.

In response to this, for example, as shown in Japanese Patent Application Laid-open No. 161654/1983, it has been proposed to provide a means for detecting the thickness of paper in a conveyance roller device disposed within the paper conveyance path. .

As shown in FIG. 6, the conventional device includes a drive roller 6 having a conveyance roller device f15 on a fixed shaft, and a pinch roller 7 that is pressed against the drive roller with a predetermined pressure. The thickness of the paper nipped between both rollers is determined by the displacement distance of the shaft 18 of the pinch roller 7.

That is, the sensor 10 is arranged relative to the shaft 18 of the pinch roller 7, and the actuator 12 of the sensor 10 is
When the rollers are oscillated, the sensor 10 outputs information on the rotation angle of the actuator, and using the information on the displacement movement of the rollers, it is possible to determine whether or not double feeding is occurring.

Then, when the paper passes through the detection section, the actuator 15 detects the angle at which the actuator 15 swings depending on the thickness of the paper,
It is designed to be able to detect single-sheet feeding and double-feeding.

However, in the conventional device as mentioned above,
It is necessary to configure the rubber roller used as the pinch roller to have a precisely circular cross section;
If there is any distortion or the like in the diameter of the roller, there will be a lot of noise in the detected value by the sensor. Therefore, there is a problem that information obtained as paper thickness data cannot be accurately determined.

(Problems to be Solved by the Invention) According to the prior art, when paper is fed, the difference in thickness between the nth sheet and the n+1th sheet is determined by comparing it with a preset reference value. It is something.

However, as the thickness of commonly used paper increases, the variation in thickness tends to increase, and the judgment of double feeding status is affected by the variation in the thickness of the white paper. , Even when there is no double feeding, it is often determined that there is a double feeding.

Furthermore, when determining double feeding using a value suitable for thick paper as a setting value, the judgment data is difficult to apply to thin paper, making it difficult to accurately judge the double feeding status of thin paper. This tends to cause problems such as the paper being fed into the image transfer section in a double feed state of 0.

(Object of the Invention) The present invention solves the drawbacks of the conventional paper double feed detection device as described above. Detects,
It is an object of the present invention to provide a device that can accurately detect a double feeding state without being affected by the thickness of paper or the like.

(Means and operations for solving the problem) The paper double feed detection device of the present invention outputs the paper thickness as an electrical signal using the paper thickness detection means provided in the paper conveyance path, and outputs the paper thickness as an electrical signal. The present invention relates to a detection device configured to determine double feeding of sheets by inputting information to a control device.

In the paper double feed detection device of the present invention, information on the thickness of paper that is continuously transported by using the information on the thickness of the paper from the detection device by the paper passing through the paper transport path. By comparing these in the control device, the double feeding state is determined. At that time, a value obtained by multiplying the difference between the data of the thickness of the nth sheet of paper and the data when there is no paper by a preset value is used to calculate the data of the thickness of the n+1th sheet of paper, Double feeding is determined by comparing the difference in data when there is no paper.

In addition, in the paper double feed detection device of the present invention, the difference between the thickness data of the nth sheet of paper and the data when there is no paper is further multiplied by another preset value. In contrast, double feeding can be determined by comparing the difference between the data on the thickness of the (n+1)th sheet and the data when there is no paper, and comparing the two at the same time.

Furthermore, in the paper double feed detection device of the present invention, the value obtained by multiplying the difference between the thickness data of the n-th sheet and the data when there is no paper by a preset value, eyes and n+
It is also possible to configure a configuration in which double feeding is determined by comparing the difference in the data of the thickness of the paper and the first sheet.

2 In addition to determining the double feed as described above, a preset value is set based on the difference between the smaller or larger value of the paper thickness data for the n-th sheet and the n+1-th sheet, and the data when there is no paper. By comparing the difference between the value multiplied by a certain value, the data on the thickness of the other paper, and the data when there is no paper, it is possible to determine double feeding. For the value obtained by multiplying the difference between the smaller value or larger value of the paper thickness data and the data when there is no paper, and the preset value, It is also possible to determine the double feeding state by comparing the difference in paper thickness data.

Therefore, in the paper double feed detection device of the present invention,
When paper is continuously sent out from the paper storage device and sent to the image transfer unit, it is possible to reliably detect the state of double feeding of paper in the area before the image transfer unit, which prevents copy errors from occurring. can be prevented.

In addition, the operation of determining the double feeding state of paper is performed by comparing the data of the paper thickness of each paper that is continuously transported. By using a value obtained by adding a certain coefficient to the difference in thickness, even if there is variation in the thickness of the paper, it can be prevented from having a large effect.

(Example) The configuration of the paper double feed detection device of the present invention will be described according to the illustrated example.

The apparatus of the present invention shown in FIG. 1 is an example of an image forming apparatus such as an electronic copying machine or a facsimile machine, in which a double feed detection device is arranged in a paper conveyance path 1 from a paper feeder to an image transfer section. There is.

The paper conveyance path 1 shown in FIGS. 1 and 1a is as follows:
As in the case of a general image forming apparatus, an upper guide plate 2 and a lower guide plate 3 are arranged at a predetermined interval so that the paper can be guided along the paper transport path.

The upper and lower guide plates 2.3 constituting the paper transport path 1 are as follows:
It is supported by the main body frame 4 via an arbitrary positioning means, and the interval between the guide plates is maintained constant.

Further, an actuator 12 is disposed at a predetermined position on the paper transport path 1 so as to press the paper passing therethrough, and the actuator 12 is supported by a sensor 10 via a shaft 11. It is designed to be swung according to the thickness of the material.

In the illustrated embodiment, the sensor uses a commonly used potentiometer, and a similar mechanism is used in the conventional example. In the present invention, the sensor 10 is provided via an abbreviated support frame 5 that is directly supported on the main body frame 4, and the sensor 10 is attached via an upright member 6 of the support frame 5. , the lower part of the actuator 12 is in contact with the upper surface of the horizontal part 7.

As mentioned above, supporting the sensor means that if the guide plate is vibrated due to the vibration of the main body of the device while paper is being conveyed, the actuator vibration data will become noisy and the reliability of the measured values will be reduced. This is to prevent the occurrence of a case where the performance deteriorates.

The swing angle of the actuator 12 is detected by the sensor 10 configured as shown in FIG. 1, and an electrical signal corresponding to the swing angle of the actuator is output. This is performed by a control device I20 as shown in the block diagram of FIG.

In the control device [20] shown in FIG.
The signal is amplified by an amplifier 25, A/D converted by an A/D converter 26, inputted to an I10 interface 23, and processed according to data from a computer 21 and a memory 22.

Further, the interface 23 is connected to an input section 27 from other sensors of the image forming apparatus, an input section 28 from an electric device, an input section 29 from an external device such as a host computer, etc. Based on the signals, the operations of controlling each device of the image forming apparatus and detecting double feeding based on the signals from the sensors are performed.

In the control device shown in FIG.
As shown in Fig. 2a, the signal input from the input signal is relatively noisy, but by taking the average value or integral value of certain portions X and X1 of the signal,
Use it as a detection signal.

(Pattern of occurrence of double feed) Since the paper fed from the paper storage device toward the paper transport path is sorted by the paper sorting device installed in the paper feeder, double feed occurs under normal conditions. There are fewer things happening. However, as described above, even when the paper is sorted by the paper sorting device, it is difficult to reliably prevent the occurrence of double feeding.

Therefore, as described above, a double feed detection means is disposed at a predetermined position on the paper conveyance path, and data on the thickness of the paper from the sensor 7 is used to determine double feed. In this case, the sheet thickness data inputted from the sensor to the control device has various patterns as shown in FIGS. 3(a) to 3(e) depending on the occurrence of double feeding.

The paper thickness signal illustrated in FIG. 3 is basically output as shown in FIG. 3(f). In other words, 1. The output value from the sensor is Vg+ when there is no paper.
When there is one sheet of paper, VPN is output, and when there are two sheets of paper, VPn+1 is output.

And the difference between the case with one sheet of paper and the case without paper is
an -Vpn-vn, and the difference between one sheet and two sheets is bn=VPn+IVPn.

In reality, the output value from the sensor is, as shown in A or B in FIG. 6, the difference between the case of one sheet and the case of two sheets of paper, which is approximately bn 7an = 2, which is only a ratio. If you take and compare the output values, the difference in output values will be doubled.

8 Therefore, in the multi-feed pattern shown in FIGS. 3(a) to e), the output value V is used to calculate the difference between when there is paper and when there is no paper, and the difference between when there is one paper and when there are two papers. I try to be able to clearly show it.

For example, if only one sheet of paper is fed,
As shown in , the detection signal is output at a low peak, and it is determined that one sheet of paper is being fed. On the other hand, if double feeding occurs on the first sheet fed from the paper feeder, and the second sheet is fed normally, as shown in figure (b)
The signal shown in is obtained.

Furthermore, if double feeding occurs on the second sheet, it is shown in (C) in the same figure, if the 1.2nd sheet is double fed, it is shown in (d), and if the nth sheet is double fed, it is shown in (e). become that way.

Then, the paper thickness signal obtained as described above is input to the control device, and using the double feed determination logic as shown below, the paper double feed detection device of the present invention detects the double feed state. Make sure to make the following decisions.

9 (Double feed determination logic) In the paper double feed detection device of the present invention, the double feed state of continuously fed sheets is determined based on the paper thickness data output from the sensor. This can be done using criteria such as those shown in the table of FIG.

In FIG. 4, which will be described later, al indicates that the signal from the first sheet of paper is used as a reference until n is reset, and an indicates that the reference value is replaced each time a comparison is made. There is. Regarding the reset of n, S
P shows the case where n is reset each time the start button of the device is pressed, and P shows the case where n is reset each time the main switch of the device is turned on.

Furthermore, one memory can be used for the paper thickness detection unit in the paper conveyance path, but as described later, one memory can be used for the paper thickness detection unit of the image forming apparatus. When the machine is equipped with a plurality of paper trays, it is also possible to provide a memory for each paper tray and to reset the corresponding memory each time a paper tray is inserted or removed.

(1) 1 in Fig. 4 is the data of the thickness of the nth sheet of paper,
Multiplying the difference in data when there is no paper by a preset value is used to compare the difference between the thickness of the n+1 sheet of paper and the data when there is no paper to prevent double feeding. This shows the case of judgment.

In the above embodiment, the data an when there is one sheet of paper is
When comparing data an+1 when there are two sheets of paper, the output value an when there is one sheet is multiplied by a preset value X, and the data of antl is calculated for Xan. I'm trying to make a comparison. Note that the set value X is X#1.5 in this case. This means that compared to the state where there is no paper, the output value in the case of one sheet is an, and the output value in the case of two sheets is different by about 2an. Therefore, if the case without paper is used as a reference, the ratio of output values for one sheet and two sheets will be doubled.

1 Therefore, by using 1 and 5, which are the intermediate values of the ratio between the case with paper and the case without paper, as the setting value,
Judgment will be made regarding double shipments.

As mentioned above, by using the value obtained by multiplying an by the setting ll1x, even if noise is mixed in the paper thickness data, if it is within the range of 1°5 times an, , there will be no errors in judgment.

(2) In the case shown in 2 of Fig. 4, in (1) above, multiply the difference between the data of the thickness of the nth sheet of paper and the data when there is no paper by a constant x 1, and then calculate n+1. The paper thickness data of the first sheet of paper is compared.

In addition, the difference between the thickness data of the n+1 sheet of paper and the data when there is no paper is compared with the value obtained by multiplying another preset value x 2, and the two values are calculated. Double feeding is determined by performing comparisons at the same time.

In the above embodiment, Xl-1, 5, 2 However, in the opposite case, the discriminant cannot make a determination.

Therefore, using the later judgment formula anti < X2 an,
To detect when the previous paper is double fed. In that case, the intermediate value between the values of n and n+1 is used as the reference value, and it is multiplied in advance by a coefficient of It can be determined that

(3) In the example shown in 3 in Figure 4, the difference an between the thickness data of the n-th sheet and the data when there is no paper is multiplied by a constant Double feeding is determined by comparing the paper thickness data difference bn with bn, and double feeding can be detected by comparing bn with >(an). .

In other words, according to this method, set X=O,S, and bn
If it is within the range of 0.5 an, it is determined to be noise, and only when the difference is greater than that, double feeding is determined.

(4) In the example shown in 4 in Figure 4, the nth and nth
+ The value obtained by multiplying the difference between the smaller or larger value of the paper thickness data for the first sheet and the data when there is no paper by a preset value, and the thickness of the other paper. Double feeding is determined by comparing the difference between the data and the data when there is no paper.

In (2) above, the data difference is processed using two set values to perform the comparison operation, but in the case of this embodiment, the larger of an and a n+1 is used. , or the smaller one, to perform the comparison operation.

If a smaller value is used, if anal>an, the smaller value an is multiplied by X, the two are compared, and an
If al>Xan, it is determined that there is a double feed.

In addition, in the case of an÷1 <an, an>xan+2
4 Condition 1 is determined to be double feeding. In this case, X=1.5 is appropriate as the central value. Similarly, when a large value is used, double feeding is determined by setting X=0.75.

Therefore, 2? If one of the data in the data is in a double feed state, if one of the comparison data is determined to be double feed by the above two comparison formulas, then either the previous paper or the following paper will be in a double feed state. It will be detected that the device is in the transmitting state.

Note that if both the n-th sheet and the n+1-th sheet are in a double-feed state, it is determined that the previous two sheets were in a double-feed state by comparison with the detection data of the subsequent paper. It will also happen.

(5) In the example shown in FIG. 5, the difference between the small value or large value of the thickness data of the nth sheet and the n+1th sheet and the data when there is no paper is set in advance. Double feeding is determined by comparing the difference in the thickness data of the n-th sheet and the n+1-th sheet with respect to the multiplied value.

In the case shown in (3) above, the data an of the thickness of the n-th sheet and the difference bn between the thickness of the n-th sheet and the n+1-th sheet are directly compared, but in the case of this method, , anal>an, the state of bn>Xan indicates a double feed, and when anti<an, an>Xbn, and it is not possible to determine a double feed.

In other words, in this method, instead of directly comparing both data, the comparison is performed using a value obtained by multiplying the smaller or larger one by X~0.5. , it is possible to accurately determine whether one of the two is double feeding.

In the control methods shown in (1) to 5) above, the determinable pattern shown in diagram M4 is (
Each double feed occurrence pattern shown in a> to e) is indicated by a symbol ■ to ■. Further, in addition to the above description, in the 6 paper double feed detection device of the present invention, the following control conditions can be set and each control operation can be performed when controlling the device.

(6) In (1) to 5) above, the preset value and the value to be multiplied are based on the difference between the data on the thickness of the first sheet of paper and the data when there is no paper. Can be set.

In other words, in this method, an is set based on the data of the thickness of the first sheet of paper, a certain coefficient will be carried out.

(7) In (1) to 6) above, the count number n can be a copy count after a copy start signal is output. In other words, each time you turn on the start button of the image forming device, n is counted.
It is possible to set the counter of the control device.

7 (8) In (1) to 6) above, the count number n can be the cumulative number of sheets fed from a plurality of paper trays after the image forming apparatus is turned on.

Therefore, in the case of an apparatus in which the paper feeding unit is equipped with a plurality of paper storage devices such as paper trays, the count number n is set based on the cumulative number of paper storage devices, regardless of which paper storage device feeds the paper. This makes it possible to determine the double feeding of paper as described above.

(9) In (1) to 6) above, a means for storing an to be compared with an÷1 is provided for each tray, and the value is reset by attaching and detaching each paper tray. I can do it. That is, when the types of paper are different for each paper tray, a reference value is set for each paper tray, and the count number n is reset by attaching or detaching the tray.

(10) In (1) to 9) above, the preset value X, etc. can be changed by a signal input from the operation panel or externally.

In other words, if the paper type is different or if you want to change the setting value
Its value can be changed by inputting it via other means.

(11) In the paper double feed detection device of the present invention, the double feed detection function can be configured to be stopped by a signal from an operation panel or an external device.

In other words, when feeding sheets containing a mixture of sheets of different thickness, there are cases where it is determined that double feeding is occurring even if double feeding is not occurring. In that case, it is possible to arbitrarily set a mode in which the paper double feed detection device is not activated.

(12) In (9) above, an to be compared with an+1
After the paper tray is set, one or more sheets of paper are sent out from the paper tray, and the setting value is determined based on the data of the thickness of the paper.

Therefore, when a paper tray is newly installed, by detecting the thickness of the paper and storing that data, double feeding can be determined from the first sheet of the next jib. I can do it.

(13) By outputting the double feed determination result to an external device, it is possible to monitor the occurrence of double feed, and it can be used for paper management, etc.

(14) By outputting the number of times of double feeding determination to an external device, it is possible to predict the maintenance time of the paper feeding device.

In contrast to the control methods of the present invention shown in (1) to (5) above, conventional detection methods as shown in Comparative Example 1 and Comparative Example 2 in FIG. 4 will be explained. In these conventional methods, for example, in the case of Comparative Example 1, data a0 n of the thickness of the nth sheet of paper is compared with a set value X, and double feeding is detected based on the magnitude of the value. The set value X is a fixed value X that is set in advance in the control device.

However, in the case of Comparative Example 1, although it is possible to detect all of (a) to e) in Fig. 3, since the set value X is a fixed value, the paper If there are variations in thickness, there is a problem in that false detection is likely to occur. Furthermore, when setting the setting value, it is necessary to correspond to conditions such as paper quality and thickness, making it difficult to set X.

In addition, in Comparative Example 2, the difference bn between the thickness of the n-th sheet and the n+1-th sheet is compared with the set value X, and if bn > X, the double transmission signal is This is what will be output.

However, since bn changes depending on the paper thickness, it is difficult to set a setting value X that corresponds to a wide range of paper thicknesses, and there are problems such as limiting the usable (determinable) paper range.

1 When each of the control methods described in (1) to (5) of the present invention is used for the comparative example, the tolerance range for the thickness variation of the paper being conveyed is This has the advantage that it is possible to take a large value, and that it is possible to easily determine the set value that is the standard for determining double feeding.

(Handling of sensors and double-feed paper) In the above-mentioned example, an actuator was attached to the potentiometer, and the actuator was brought into direct contact with the paper, and the swing angle was converted into an electrical signal, which was judged by the double-feed determination device. Also, it is possible to use a detection means that outputs the difference between no paper, one sheet, and two sheets as an electric signal.

For example, the present invention can be applied to conventional photosensors, means for detecting roller displacement, etc., although the accuracy will be lower. Further, as a device for detecting things other than paper thickness, it can also be applied to detecting the capacitance of paper. However, as mentioned above, it is desirable that the outputs of these outputs change linearly (no paper, 1 sheet, and 2 sheets)2.

Note that the paper double feed detection device of the present invention described above can be placed at any position on the paper transport path.
When double feeding of paper is detected by the sensor, a command can be outputted to stop the conveyance of the paper and to remove the paper that has caused the double feeding.

In addition, unlike the jam handling in the case of a normal copier, in the case of a laser beam printer that is connected to a computer, the paper that has caused the double feed is directed to an output tray that is different from the copy storage tray. It is also possible to perform processing such as sending out the data.

Further, the paper double feed detection device of the present invention can be applied to any electrophotographic copying machine, etc. in addition to high-speed laser printers used as image forming devices, and the paper double feed detection device of the present invention can be applied to any electrophotographic copying machine or the like. There are no particular limitations on the location of the .

3 (Effects of the Invention) Since the paper double feed detection device of the present invention has the above-described configuration, when the paper is continuously fed from the paper storage device and fed into the image transfer section, the paper double feed detection device of the present invention detects the image It is possible to reliably detect the state of double feeding of paper in the area in front of the transfer unit, and it is possible to prevent the occurrence of copy mistakes.

In addition, the operation of determining the state of paper multifeeding is performed by comparing the data of the paper thickness of each paper that is continuously transported, and when comparing the data, the paper thickness By using a value obtained by adding a certain coefficient to the difference, there is no need to limit the thickness of the paper, and it is possible to accurately determine whether double feeding is occurring or not.

[Brief explanation of drawings]

FIG. 1 is a front view showing the configuration of the paper double feed detection device of the present invention, FIG. 1a is a side view thereof, FIG. 2 is a block diagram showing the configuration of the control device of the present invention, and FIG. 2a is a sensor Explanatory diagrams of the obtained detection signals, 4 Figures 3(a) to 3(e) each show the generation pattern of multiplexed signals from the sensor, and Figure 3(f) shows the state of the actual output signal. 4 is a diagram showing the double feed determination theory, FIG. 5 is a graph showing the relationship between the number of sheets of paper and the output in the detection device, and FIG. 6 is the configuration of a conventional paper double feed detection device. FIG. Reference numeral 1 in the figure: paper conveyance path, 5: support frame, 10: sensor, 12: actuator, 15: Conveyance roller device, 20・
·····Control device. Figure 1 Figure 1α POWI: Scale O~

Claims (14)

[Claims] (1) A detection device configured to provide a paper thickness detection means in the paper conveyance path, output the paper thickness as an electrical signal, and input the signal to a control device to determine double feeding of paper. The apparatus is configured to input information on the thickness of continuously conveyed sheets to a control device and compare the sheets using the sheet thickness information from the detecting device as the sheets pass through the sheet conveyance path. By doing this, when determining the multifeed status, n
Using a value obtained by multiplying the difference between the data on the thickness of the th sheet of paper and the data when there is no paper by a preset value, the data on the thickness of the n+1th sheet of paper and the data when there is no paper are A paper double feed detection device that determines double feed by comparing data differences. (2) The thickness of the n+1th sheet of paper is also calculated by multiplying the difference between the thickness data of the nth sheet of paper and the data when there is no paper by another preset value. The data and
2. The paper double feed detection device according to claim 1, wherein double feed is determined by comparing data differences when there is no paper and performing two comparisons at the same time. (3) Calculate the thickness of the n-th sheet and the n+1-th sheet of paper by multiplying the difference between the thickness data of the n-th sheet and the data when there is no paper by a preset value. 2. The double feed detection device for sheets according to claim 1, wherein double feed is determined by comparing the difference in paper width data. (4) The value obtained by multiplying the difference between the smaller value or larger value of the paper thickness data for the n-th sheet and the n+1-th sheet and the data when there is no paper by a preset value, and A double feed detection device for paper according to claim 1, characterized in that double feed is determined by comparing the difference between the thickness data of one paper and the data when there is no paper. . (5) For the value obtained by multiplying the difference between the smaller or larger value of the paper thickness data for the n-th sheet and the n+1-th sheet and the data when there is no paper by a preset value. 2. The double feed detection device for sheets according to claim 1, wherein the double feed is determined by comparing the difference in thickness data of the nth sheet and the n+1th sheet. (6) The value to be multiplied by the preset value is the difference between the data on the thickness of the first sheet and the data when there is no sheet. The paper double feed detection device according to any one of Item 5. (7) The paper double feed detection device according to any one of claims 1 to 6, wherein the count number n is a copy count after a copy start signal is output. (8) Claims 1 to 6, characterized in that the count number n is the cumulative number of sheets fed from a plurality of paper trays after the image forming apparatus is turned on.
2. The paper double feed detection device according to any one of paragraphs. (9) A claim characterized in that means for storing a value an to be compared with a preset value an+1 is set corresponding to each tray, and the value is reset by attaching and detaching each paper tray. The paper double feed detection device according to any one of Items 1 to 6. (10) Any one of claims 1 to 6 or 9, characterized in that the preset value can be changed by a signal input from an operation panel or from the outside. A double feed detection device for paper described in . (11) The double feed detection function is configured to be stopped by a signal from an operation panel or an external device, as set forth in any one of claims 1 to 6 or 9. Double feed detection device for paper. (12) After setting the paper tray, one or more sheets of paper are automatically run, and the thickness data of the paper is used as the initial thickness data.
Double feed detection device for paper as described in section. (13) The double feed detection device for sheets according to any one of claims 1 to 12, which outputs the result to an external device when a double feed is determined. (14) Double feeding of paper according to any one of claims 1 to 13, characterized by having means for storing the number of times determined to be double feeding, and outputting the number of times to an external device. Detection device.