JP2010173821A - Transfer-member positional displacement measuring device, thickness measuring device, double-feed detection device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thickness measuring device or the like for measuring a thickness of a transfer object even if the transfer object remains in an unstable transfer state. <P>SOLUTION: The image forming device 10 includes: a rotary roller 290 rotating in contact with a recording sheet to transfer the recording sheet; a position detecting device 300 detecting a position in a direction of the rotary roller 290 in which the recording sheet is held in contact with the rotary roller 290; and a control circuit 362 acquiring a detected value, detected by the position detecting device 300, at predetermined time intervals during a period of one revolution and more of the rotary roller 290 and controlling acquisition of the detected value, detected by the position detecting device 300, depending on the transfer state in which the recording sheet is transferred by the rotary roller 290. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a conveying member position variation measuring device, a thickness measuring device, a double feed detecting device, and an image forming apparatus.

  Patent Document 1 includes a roller pair for conveying a paper sheet, a thickness detecting unit that outputs a signal corresponding to the displacement amount of the roller pair generated by the paper sheet held between the roller pair, A means for determining double feed by sampling the output of the thickness detecting means for a period of at least one rotation of the roller pair in order to cancel the eccentric error of the roller pair, wherein n is an integer of 2 or more The average value of the output sampled during a period when the roller pair rotates at least once while the paper sheet is held and conveyed by the roller pair, and the average value and the (n-1) th paper. The difference between the average value of the output sampled during a period in which the roller pair rotates at least once while the leaf body is nipped and conveyed by the roller pair is compared with a predetermined first value, and this comparison is performed. Based on the result, the weight of the nth paper sheet Paper weighing feed detecting device is disclosed having a discriminating means for discriminating (see Patent Document 1).

Japanese Patent Publication No. 07-84278

  According to the present invention, there is provided a transport member position fluctuation amount detection device capable of measuring a position variation of a transport member even if the transport state of the transported body is unstable, and a transport state of the transported body is unstable. In addition, a thickness measuring device that can measure the thickness of the transported body, a double feed detection device that can detect double feed even if the transport state of the transported body is unstable, and such a thickness An object of the present invention is to provide an image forming apparatus having at least one of a height measuring device and a multifeed detecting device.

  The present invention according to claim 1 is a position detection that detects a position of a conveying member that rotates while being in contact with the object to be conveyed and conveys the object to be conveyed, and a position of the conveying member in a direction in contact with the object to be conveyed. Means for acquiring the detection value detected by the position detection means at a predetermined time interval while the conveyance member makes one rotation or more, and a conveyance state in which the conveyance member conveys the object to be conveyed. And a control means for controlling the acquisition means in response.

  The present invention according to claim 2 is the conveyance member position variation measuring device according to claim 1, wherein the control means stops acquisition of the detection value by the acquisition means when the rotation speed of the conveyance member changes.

  The present invention according to claim 3 is the conveyance member position fluctuation amount measuring device according to claim 2, wherein the control means restarts the acquisition of the detection value by the acquisition means when the rotation speed of the conveyance member becomes constant. .

  The present invention according to claim 4 further includes a drive source that transmits drive to the transport member, and the control unit is configured to use the acquisition unit when drive transmission from the drive source to the transport member is cut off. The conveyance member position variation measuring device according to claim 1, wherein acquisition of the detection value is stopped.

  According to a fifth aspect of the present invention, in the conveyance member according to the fourth aspect, the control unit resumes the acquisition of the detection value by the acquisition unit when the drive transmission from the drive source to the conveyance member is resumed. This is a position variation measuring device.

  According to a sixth aspect of the present invention, there is provided a transport member that rotates while being in contact with a transported body and transports the transported body, and a position detection that detects a position of the transport member in a direction in contact with the transported body. Means, an acquisition means for acquiring the detection value detected by the position detection means at a predetermined time interval while the conveyance member makes one rotation or more, and when the rotation speed of the conveyance member changes, the acquisition means And a conversion unit that converts the acquired detection value so that the rotation speed of the conveyance becomes a constant detection value.

  The present invention according to claim 7 further includes a rotation speed measurement unit that measures a rotation speed of the transport member, and the conversion unit uses the rotation speed of the transport member measured by the rotation speed measurement unit. The transport member position variation measuring device according to claim 6, wherein the detection value acquired by the acquisition means is converted.

  According to an eighth aspect of the present invention, in the transport member position according to the sixth aspect, the conversion means converts the detection value acquired by the acquisition means based on information on the rotational speed of the transport member stored in advance. It is a variation measuring device.

  The present invention according to claim 9 is a position detection that detects a position of a conveyance member that rotates in a state of contact with the object to be conveyed and conveys the object to be conveyed, and a position of the conveyance member in a direction in contact with the object to be conveyed. Means for acquiring the detected value detected by the position detecting means over a period of one rotation or more of the conveying member at predetermined time intervals, and the conveying member when conveying the object to be conveyed A thickness calculating means for calculating a thickness of the transported body from a difference between a position variation amount and a position variation amount of the transport member when the transported body is not transported; And a control unit that controls the acquisition unit in accordance with a conveyance state of conveyance.

  According to a tenth aspect of the present invention, there is provided a transport member that rotates while being in contact with a transported body and transports the transported body, and a position detection that detects a position of the transport member in a direction in contact with the transported body. Means, an acquisition means for acquiring the detection value detected by the position detection means at a predetermined time interval while the conveyance member makes one rotation or more, and when the rotation speed of the conveyance member changes, the acquisition means Conversion means for converting the acquired detection value to a detection value at which the rotation speed of the conveyance is constant, a position variation amount of the conveyance member when the conveyance object is conveyed, and a conveyance object And a thickness calculator that calculates the thickness of the transported body from the difference from the position variation amount of the transport member when the transport member is not transported.

According to an eleventh aspect of the present invention, there is provided a transport member that rotates while being in contact with a transported body and transports the transported body, and a position detection that detects a position of the transport member in a direction in contact with the transported body. Means for acquiring the detected value detected by the position detecting means over a period of one rotation or more of the conveying member at a predetermined time interval, and the thickness of the object to be conveyed from the position variation amount of the conveying member. Thickness calculating means for calculating the thickness, dn is the thickness of the N (N ≧ 2) integer transported object calculated by the thickness calculating means, and d0 is calculated by the thickness calculating means When the average value of the thicknesses of at least one transported object up to the (N-1) th sheet is satisfied and dn ≧ d0 × α (1 <α <2) is satisfied, double feed occurs in the transported object. According to the transport state in which the multi-feed determining means determines that the transport member is transporting the transported body. And control means for controlling said acquiring means,
Is a double feed detection device.

  According to a twelfth aspect of the present invention, there is provided a transport member that rotates while being in contact with a transported body and transports the transported body, and a position detection that detects a position of the transport member in a direction in contact with the transported body. Means, an acquisition means for acquiring the detection value detected by the position detection means at a predetermined time interval while the conveyance member makes one rotation or more, and when the rotation speed of the conveyance member changes, the acquisition means A conversion unit that converts the acquired detection value so as to be a detection value at which the rotation speed of the transfer is constant; and a thickness calculation unit that calculates the thickness of the object to be transferred from the amount of position fluctuation of the transfer member; , Dn is the thickness of the N (N ≧ 2) -th transported object calculated by the thickness calculating means, and d0 is at least one up to the (N-1) th sheet calculated by the thickness calculating means. It is set as the average value of the thickness of the to-be-conveyed body more than a sheet | seat, dn> = If the 0 × α (1 <α <2) is satisfied, a double feed detection device having a multi-feed determining means for determining a double feed in the carrier occurs.

  According to a thirteenth aspect of the present invention, there is provided a thickness measuring device that measures the thickness of the transported body, an image forming unit that forms an image on the transported body whose thickness is measured by the thickness measuring device, An image forming condition control unit that controls image forming conditions of the image forming unit based on the thickness of the conveyed object measured by the thickness measuring apparatus, and the thickness measuring apparatus comprises: A conveying member that rotates while being in contact with the conveying member, conveys the conveying member, a position detecting unit that detects a position of the conveying member in a direction in contact with the conveying member, and a detection value detected by the position detecting unit Obtaining means for obtaining the rotation of the conveying member at a predetermined time interval during one rotation or more, a position variation amount of the conveying member when conveying the conveyed object, and conveying the conveyed object The thickness of the transported body is calculated from the difference from the position variation amount of the transport member when there is not An image forming apparatus having the calculating means, and control means for controlling said acquiring means in accordance with the conveyance state in which the conveying member to convey the object to be transferred.

  According to a fourteenth aspect of the present invention, there is provided a thickness measuring device that measures the thickness of a transported member, an image forming unit that forms an image on the transported member whose thickness is measured by the thickness measuring device, An image forming condition control unit that controls image forming conditions of the image forming unit based on the thickness of the conveyed object measured by the thickness measuring apparatus, and the thickness measuring apparatus comprises: A conveying member that rotates while being in contact with the conveying member, conveys the conveying member, a position detecting unit that detects a position of the conveying member in a direction in contact with the conveying member, and a detection value detected by the position detecting unit Acquisition means for obtaining the rotation of the conveying member at a predetermined time interval and when the rotation speed of the conveying member changes, the detection value acquired by the obtaining means is set to the rotation speed of the conveyance. Conversion means for converting the detection value to be constant; Thickness for calculating the thickness of the transported body from the difference between the position variation amount of the transport member when transporting the transport body and the position variation amount of the transport member when not transporting the transported body And an arithmetic unit.

  According to a fifteenth aspect of the present invention, an image forming unit that forms an image on a transported member, a transport device that transports the transported member to the image forming unit, and multi-feed to the transported member being transported by the transporting device. A double feed detection device that detects whether or not it occurs, and a control unit that controls at least one of the image forming unit and the transport device based on a detection result by the double feed detection device; The multi-feed detection device rotates in a state of being in contact with the transported body and transports the transported body; and a position detection unit that detects a position of the transport member in a direction in contact with the transported body. An acquisition means for acquiring a detection value detected by the position detection means over a predetermined time interval while the conveyance member makes one or more rotations; and when the rotation speed of the conveyance member changes, the acquisition value is acquired by the acquisition means. The detected value Conversion means for converting the rotation speed to a detection value that is constant, thickness calculation means for calculating the thickness of the transported body from the amount of position fluctuation of the transport member, and dn, the thickness calculation means The thickness of the N-th transported body calculated in step (N ≧ 2), and d0 is the thickness of at least one transported body up to the (N-1) th transported body calculated by the thickness calculation means. And a double feed determination unit that determines that double feed has occurred in the conveyed object when dn ≧ d0 × α (1 <α <2) is satisfied. .

  According to a sixteenth aspect of the present invention, there is provided an image forming unit that forms an image on a transported member, a transporting device that transports the transported member to the image forming unit, and a multifeed to the transported member being transported by the transporting device. And a control unit that controls at least one of the image forming unit and the conveyance device based on a detection result by the multifeed detection device, and The double feed detection device rotates in a state of being in contact with the transported body and transports the transported body, and a position detection unit that detects a position of the transport member in a direction in contact with the transported body, An acquisition unit that acquires a detection value detected by the position detection unit over one rotation of the conveyance member at predetermined time intervals, and acquired by the acquisition unit when the rotation speed of the conveyance member changes. Rotate the detected value Conversion means for converting the detected value to be a constant detection value, thickness calculating means for calculating the thickness of the transported body from the amount of positional fluctuation of the transport member, and dn by the thickness calculating means The calculated thickness of the N-th object to be transported (N ≧ 2) is the thickness of the transported body, and d0 is the thickness of at least one transported body up to the (N-1) th transported body calculated by the thickness calculating means. The image forming apparatus includes an average value, and a multi-feed determining unit that determines that multi-feed occurs on the transported body when dn ≧ d0 × α (1 <α <2) is satisfied.

  According to the first aspect of the present invention, it is possible to provide a transport member position variation measuring device capable of measuring the position variation of the transport member even when the transport state of the transported body is unstable.

  According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, the position variation amount of the conveying member is measured at the timing when the measurement of the positional variation amount of the conveying member becomes inaccurate. It is possible to provide a conveyance member position variation measuring device capable of stopping the measurement.

  According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, in addition to the measurement of the position variation amount of the conveying member at the timing when the position variation amount of the conveying member becomes accurate. It is possible to provide a conveyance member position fluctuation amount measuring device that can restart the operation.

  According to the fourth aspect of the present invention, in addition to the effect of the first aspect of the present invention, the position variation amount of the conveying member is measured at a timing at which the measurement of the positional variation amount of the conveying member becomes inaccurate. It is possible to provide a conveyance member position variation measuring device capable of stopping the measurement.

  According to the fifth aspect of the present invention, in addition to the effect of the fourth aspect of the present invention, in addition to the measurement of the positional variation amount of the conveying member at the timing when the positional variation amount of the conveying member becomes accurate. It is possible to provide a conveyance member position fluctuation amount measuring device that can restart the operation.

  According to the sixth aspect of the present invention, it is possible to provide a transport member position variation measuring device capable of measuring the position variation of the transport member even if the transport state of the transported body is unstable.

  According to the seventh aspect of the present invention, in addition to the effects of the sixth aspect of the present invention, it is possible to measure the position variation of the conveying member even if the speed of the conveyed object changes. A member position variation measuring device can be provided.

  According to the present invention of claim 8, in addition to the effect of the present invention of claim 6, in addition to being able to measure the position variation of the transport member even if the speed of the transported body changes A member position variation measuring device can be provided.

  According to the ninth aspect of the present invention, it is possible to provide a thickness measuring apparatus capable of measuring the thickness of the transported body even when the transported state of the transported body is unstable.

  According to the tenth aspect of the present invention, it is possible to provide a thickness measuring apparatus capable of measuring the thickness of the transported body even if the transported state of the transported body is unstable.

  According to the eleventh aspect of the present invention, it is possible to provide a double feed detection device capable of detecting double feed even when the transport state of the transported body is unstable.

  According to the twelfth aspect of the present invention, it is possible to provide a double feed detection device capable of detecting double feed even when the transport state of the transported body is unstable.

  According to the thirteenth aspect of the present invention, there is provided an image forming apparatus having a thickness measuring device capable of measuring the thickness of the conveyed object even if the conveyed state of the conveyed object is unstable. Can do.

  According to the fourteenth aspect of the present invention, there is provided an image forming apparatus having a thickness measuring device capable of measuring the thickness of a conveyed object even if the conveyed state of the conveyed object is unstable. Can do.

  According to the fifteenth aspect of the present invention, it is possible to provide an image forming apparatus having a double feed detection device capable of detecting double feed of a transported body even if the transport state of the transported body is unstable. it can.

According to the sixteenth aspect of the present invention, it is possible to provide an image forming apparatus having a double feed detection device capable of detecting double feed of a transported body even if the transport state of the transported body is unstable. it can.

1 is a front view showing an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a front view illustrating a sheet feeding device included in the image forming apparatus illustrated in FIG. 1. It is a perspective view which shows the position detection apparatus which the image forming apparatus shown in FIG. 1 has. It is a front view which expands and shows the principal part of the position detection apparatus shown in FIG. FIG. 2 is a block diagram illustrating a control unit included in the image forming apparatus illustrated in FIG. 1. It is a 1st figure explaining the principle of the position detection apparatus shown in FIG. It is a 2nd figure explaining the principle of the position detection apparatus shown in FIG. It is a 2nd figure explaining the principle of the position detection apparatus shown in FIG. FIG. 4 is a diagram for explaining the principle of determining whether or not double feeding of recording sheets occurs using the position detection device shown in FIG. 3. 3 is a flowchart illustrating control by a control unit included in the image forming apparatus illustrated in FIG. 1. FIG. 5 is a first diagram illustrating the principle of a position detection device included in an image forming apparatus according to a second embodiment of the present invention. It is a 2nd figure explaining the principle of the position detection apparatus which the image forming apparatus which concerns on the 2nd form of this invention has. It is a front view which shows the 1st modification of the position detection apparatus which the image forming apparatus which concerns on the 1st form of this invention and the image forming apparatus which concerns on the 2nd form of this invention has. It is a front view which shows the 2nd modification of the position detection apparatus which the image forming apparatus which concerns on the 1st form of this invention and the image forming apparatus which concerns on the 2nd form of this invention has. It is a figure explaining the 1st Example of this invention. It is a figure explaining the 2nd Example of this invention.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated with reference to drawings.

FIG. 1 is a front view showing an image forming apparatus 10 according to the first embodiment of the present invention.
The image forming apparatus 10 optically reads an image of the document D placed on the platen 12, converts the image into electrical image data by the CCD sensor 14, and transfers the image from the image input unit 20. An image output unit 30 that forms an image on a recording sheet used as a transported body based on the image information that has been processed. An ADF 16 that automatically feeds the document D to the platen 12 can be attached to the image input unit 20.

  The image output unit 30 presses and heats the image forming unit 32 that forms an unfixed image with a developer on the recording sheet based on the image data, and pressurizes and heats the unfixed image formed on the recording sheet by the image forming unit 32. And a fixing device 60 that fixes the recording sheet.

  The image output unit 30 forms a toner image on the photosensitive drum 34 based on the image data transferred from the image input unit 20, and then primarily transfers the toner image to an endless transfer belt 36, and further transfers the toner image. The toner image on the belt 36 is secondarily transferred to the recording sheet to form an unfixed image on the recording sheet, and the recording sheet on which the toner image is secondarily transferred passes through the fixing device 60 and is placed on the discharge tray 62. It is supposed to be discharged.

  The photosensitive drum 34 rotates in a direction indicated by an arrow at a predetermined process speed, and a charging device 38 that uniformly charges the surface of the photosensitive drum 34 to a predetermined background portion potential around the photosensitive drum 34 and image data. A latent image forming device 40 that exposes the photosensitive drum 34 with a laser beam modulated on the basis thereof to form an electrostatic latent image on the photosensitive drum 34, and a developing device that develops the electrostatic latent image on the photosensitive drum 34. 42, a pre-transfer charge eliminating device 44 for removing the potential on the photosensitive drum 34 prior to the primary transfer of the toner image to the transfer belt 36, and the residual on the photosensitive drum 34 after the primary transfer of the toner image is completed. A cleaning device 46 for removing toner is disposed.

  The transfer belt 36 is wound around a plurality of rolls and rotated in the direction of the arrow, and the toner image formed on the photosensitive drum 34 is transferred to the transfer belt 36 and then transferred from the transfer belt 36 to the recording sheet. Secondary transfer is performed. A primary transfer roll 50 that forms a transfer electric field with the photosensitive drum 34 is provided at a position facing the photosensitive drum 34 across the transfer belt 36, while a secondary transfer position of the toner image is provided at the secondary transfer position. The transfer roll 52 and the counter electrode roll 54 are provided with the transfer belt 36 interposed therebetween, and the recording sheet is inserted between the secondary transfer roll 52 and the transfer belt 36 and passed to transfer the toner image. Has been. Further, a belt cleaner 56 that removes paper dust and residual toner from the surface of the transfer belt 36 where the secondary transfer is completed is between the secondary transfer position and the primary transfer position in the rotation path of the transfer belt 36. Is provided.

  Further, below the image output unit 30, four paper feeding devices 150 for supplying recording sheets to the image output unit 30 are provided. Each of the sheet feeders 150 includes storage containers 152 that store recording sheets of different sizes, for example. The recording sheet of the selected size is sent out from any of the storage containers 152 toward the image output unit 30.

  A transport roll 170 is provided on the downstream side of each storage container 152 in the transport direction of the recording sheet. Further, a conveyance roll 200 is provided on the downstream side of the four conveyance rolls 170 in the conveyance direction of the recording sheet. Further, a resist roll 172 is provided further downstream of the transport roll 200 and upstream of the secondary transfer position. The registration rolls 172 are secondarily transferred at a predetermined timing in synchronization with the writing timing of the electrostatic latent image on the photosensitive drum 34 from the recording sheets sent out from the respective storage containers 152 and conveyed by the respective conveyance rolls 170. It is designed to send to the position.

  A rotating roll 290 used as a rotating member that rotates in contact with the recording sheet is in contact with the conveying roll 200 so as to sandwich a conveying path through which the recording sheet is conveyed. The rotary roll 290 is used to transport the recording sheet together with the transport roll 200.

  In addition, a position detecting device 300 used as position detecting means for detecting a position when the recording sheet of the rotating roll 290 is conveyed is attached to the rotating roll 290.

  In this embodiment, the image forming apparatus 10 includes four paper feeding devices 150, but the number of paper feeding devices may be other than four.

  Further, the image forming apparatus 10 includes a manual feed unit 72 used for manual feeding of recording sheets.

  The image forming apparatus 10 also includes a sheet conveying belt 74 that feeds the recording sheet onto which the toner image has been secondarily transferred to the fixing device 60.

  The image forming apparatus 10 also includes an inverter path 76 that is conveyed again to the image forming unit 32 in order to reverse the recording sheet on which the image is formed on one side by the image forming unit 32 and the fixing device 60 to form an image on both sides. Have.

  In the image forming apparatus 10 configured as described above, the latent image forming apparatus 40 exposes the photosensitive drum 34 based on the image data of the original captured by the image input unit 20, and the image data is transferred onto the photosensitive drum 34. The electrostatic latent image corresponding to is written. The written electrostatic latent image is developed by the developing device 42. The toner image thus formed is primarily transferred onto the transfer belt 36 by the primary transfer roll 50, and the transfer belt 36 rotates while holding the toner image. The toner image primarily transferred onto the transfer belt is secondarily transferred to the recording sheet sent from the conveying roll 170 at a predetermined timing, and the recording sheet on which the unfixed image is transferred passes through the fixing device 60 and is discharged to the discharge tray 62. To be discharged.

  FIG. 2 shows the paper feeding device 150 arranged at the top of the four paper feeding devices 150. The other three sheet feeders 150 are the same as the uppermost sheet feeder 150, although the size of the container 152 is different.

  As shown in FIG. 2, the paper feeding device 150 includes a pickup roll 154 that is pressed against the uppermost surface of the recording sheet stored in the storage container 152 described above. The pickup roll 154 feeds the recording sheet by moving the contact surface with the recording sheet in the left direction in the figure.

  The pickup roll 154 is provided at the leading end of the stacked recording sheets. For example, the pickup roll 154 is provided at a position 20 mm from the leading end of the recording sheet on which the vertical center axis of the pickup roll 154 is stacked. The pickup roll 154 is rotationally driven in a clockwise direction by a rotation driving device (not shown) when feeding the recording sheet.

The pickup roll 154 is provided with a pressure contact force adjusting device (not shown) that adjusts the pressure contact force pressed against the recording sheet. Examples of the pressure contact force adjusting device include a drive device that can move an axis provided at the center of rotation of the pickup roll 154 in the vertical direction.

  The paper feeding device 150 has a separation mechanism 156. The separation mechanism 156 is provided on the downstream side of the pickup roll 154 in the sheet conveyance direction, and separates into one recording sheet when the recording sheet sent out by the pickup roll 154 is double-fed.

  The separation mechanism 156 is disposed to face the feed roll 158 that conveys the recording sheet in the left direction in the drawing and the feed roll 158 so as to form a press-contact portion N. And a retard roll 160 biased in the opposite direction.

  The feed roll 158 is provided in a substantially horizontal direction with respect to the pickup roll 154.

  The feed roll 158 is provided with a rotation drive device (not shown) that rotates the feed roll 158 in the clockwise direction.

  The retard roll 160 is provided such that the rotation center of the retard roll 160 is substantially downward in the vertical direction with respect to the rotation center of the feed roll 158.

  The retard roll 160 is provided with a rotation drive device (not shown) so as to be urged clockwise.

  An initial urging force (initial torque) T0 is applied to the retard roll 160. The frictional force between the retard roll 160 and the recording sheet when one recording sheet enters the press contact portion N is F1, and the frictional force between the recording sheets when a plurality of recording sheets enter the press contact portion N. Is F2, and the radius of the retard roll 160 is R, the initial torque T0 is determined so as to satisfy the relationship F1> T0 ÷ R> F2.

  Further, the retard roll 160 is provided with an urging force adjusting device (not shown) that adjusts the urging force (torque) on which the retard roll 160 is urged.

  Examples of the urging force adjusting device include a device that can increase or decrease the driving force applied to the rotation driving device of the retard roll 160.

  In addition, when the retard roll 160 is comprised with a torque limiter, the rotational drive apparatus and urging | biasing force adjustment apparatus of the retard roll 160 can be abbreviate | omitted.

FIG. 3 shows a transport roll 200, a rotary roll 290, and a position detection device 300.
The transport roll 200 includes transport roll main bodies 202 and 202, and a transport roll shaft 204 that rotates integrally with the transport roll main bodies 202 and 202. Bearings 206 and 206 are mounted on the transport roll shaft 204, and the transport roll 200 is mounted so as to be able to rotate on the main body of the image forming apparatus 10 using the bearings 206 and 206.

  A gear 208 is attached to, for example, one end of the transport roll shaft 204. Drive from a motor 240 used as a drive source is transmitted to the gear 208 via an electromagnetic clutch 244 and a gear 282. The electromagnetic clutch 244 is used to transmit the drive from the motor 240 to the transport roll 200 and to disconnect the drive transmission from the electromagnetic clutch 244 to the transport roll 200.

  The rotary roll 290 is used to contact the conveyance roll 200 directly or via a recording sheet, follow the conveyance roll 200, and convey the recording sheet together with the conveyance roll 200. The rotating roll 290 includes rotating roll bodies 292 and 292 and a rotating roll shaft 294 that rotates together with the rotating roll bodies 292 and 292. Further, the rotary roll 290 is urged by a biasing means (not shown) such as a coil spring, for example, with the rotary roll main bodies 292 and 292 in contact with the transport roll main bodies 202 and 202. Is pressed. Further, as indicated by an arrow in FIG. 3, the rotary roll 290 is supported so as to be able to move in the direction of approaching and separating from the transport roll 200 with respect to the main body of the image forming apparatus 10.

  When the leading end of the recording sheet is inserted between the rotating roll main bodies 292 and 292 and the conveying roll main bodies 202 and 202, the rotating roll 290 moves away from the conveying roll 200 (upward in FIG. 3). Moving. Further, when the trailing edge of the recording sheet passes through the portion where the rotating roll main bodies 292 and 292 and the conveying roll main bodies 202 and 202 come into contact, the rotating roll 290 approaches the conveying roll 200 (in FIG. 3). Move down).

  The position detection device 300 includes an actuator 302 that contacts the rotating roll shaft 294, follows the rotating roll shaft 294, and is displaced to rotate, and an angle sensor 304 that detects a displacement angle of the actuator 302. The position detection device 300 detects the position of the rotary roll 290 away from the transport roll 200 that is the direction indicated by the arrow in FIG.

  A rotary encoder 320 used as a rotation angle detection unit that detects a rotation angle from the reference position of the rotary roll 290 is attached to, for example, the rotary roll shaft 294 of the rotary roll 290. The rotary encoder 320 is also used as a rotational speed measuring unit that measures the rotational speed of the rotary roll 290.

  The output from the position detection device 300 and the output from the rotary encoder 320 are input to a control circuit 362 (see FIG. 5) described later.

  FIG. 4 is a side view showing the vicinity of the transport roll 200, the rotary roll 290, and the position detection device 300. A pair of plate-like members 284 and 284 facing each other are provided in the vicinity of the conveyance roll 200 and the rotation roll 290 so that the recording sheet is guided between the conveyance roll 200 and the rotation roll 290. A conveyance path 286 used for conveying the recording sheet is formed between the two.

  Further, a recording sheet detection sensor 340 that detects the presence or absence of the recording sheet is provided on the downstream side in the conveying direction of the recording sheet at a position where the conveying roll 200 and the rotating roll 290 are in contact with each other. The output from the recording sheet detection sensor 340 is output to the above-described control circuit 362 (see FIG. 3).

FIG. 5 shows the control unit 360.
The control unit 360 includes a control circuit 362 composed of, for example, a CPU, and image signals from the image input unit 20 and, for example, a personal computer outside the image forming apparatus 10 are input to the control circuit 362 via the communication interface 364. An image signal is output from the control circuit 362 to the image forming unit 32. Further, the control circuit 362 receives the output from the position detection device 300, the output from the rotary encoder 320, and the output from the recording sheet detection sensor 340.

  Further, the motor 240 is controlled by the output from the control circuit 362. For example, the control circuit 362 starts the rotation of the motor 240 and stops the rotation of the motor 240. In addition, the control circuit 362 controls the electromagnetic clutch 244 so that the motor 240 and the transport roll 200 are connected and disconnected.

  In addition, the control circuit 362 is used as an acquisition unit that acquires the detection value detected by the position detection device 300 while the rotary roll 290 makes one rotation or more at predetermined time intervals. In addition, the control circuit 362 is used as a control unit that controls acquisition of a detection value detected by the one detection unit 300 in accordance with a conveyance state in which the rotary roll 290 conveys a recording sheet. Further, the control circuit 362 is used as a thickness calculating means for calculating the thickness of the recording sheet. In addition, the control unit 360 is used as a multifeed determination unit that determines whether or not a multifeed has occurred in the recording sheet using the calculated thickness of the recording sheet.

  FIG. 6 illustrates the principle by which the control circuit 362 calculates the displacement of the rotating roll 290, particularly the principle of calculating the displacement of the rotating roll 290 when the rotation of the rotating roll 290 is stable. The control circuit 362 calculates the displacement of the rotating roll 290 not only when the rotation of the rotating roll 290 is stable but also when the rotation of the rotating roll 290 is unstable. The following calculation principle when the rotation of the rotary roll 290 is stable is a premise of the principle of calculating the displacement of the rotary roll 290 when the rotation of the rotary roll 290 is unstable. Here, as a case where the rotation of the rotary roll 290 is unstable, for example, a case where the rotational speed of the rotary roll 290 changes can be cited. Moreover, as a case where rotation of the rotation roll 290 is unstable, the case where the drive transmission from the motor 240 to the conveyance roll 200 is cut | disconnected can be mentioned, for example.

  The graph in FIG. 6 shows the output of the position detection device 300 when the rotary roll 290 makes one rotation or more.

  The range indicated by the arrow in FIG. 6 indicates the time when the rotating roll 290 makes one rotation.

  Reference numerals 01 to 17 in FIG. 6 indicate sampling data arrays used as detection values. The sampling data array is a data array in which the detection values detected by the position detection device 300 are acquired at predetermined time intervals while the rotating roll 290 is rotated once or more.

In the present embodiment, the mean value _d 0 (0) of the sampled data sequence from 01 to 13, the average value of the sampling data sequences up 03~15 _d 0 (1), and the average of the sampled data sequences up 05-17 The value d ₀ (2) is calculated, and the average value d ₀ (0), the average value d ₀ (1), and the average value of the average value d ₀ (2) are further calculated.

  That is, in this embodiment, the sampling data array detected by the position detection device 300 is acquired while the rotating roll 290 makes one rotation or more at a predetermined time interval, and the rotating roll 290 of the acquired sampling data array is included in the acquired sampling data array. The average value of the sampling data array for one rotation is calculated three times, which is a predetermined number of times by shifting the predetermined time interval, and the calculated three average values are further averaged to calculate the position fluctuation amount of the rotary roll 290. .

  FIG. 7 illustrates the principle by which the control circuit 362 calculates the displacement of the rotating roll 290 and includes the state in which the rotation of the rotating roll 290 is unstable. ing. In FIG. 7, the displacement of the rotating roll 290 when the control circuit 362 determines that the rotation of the rotating roll 290 is unstable by disconnecting the drive transmission from the motor 240 to the transport roll 200. The principle of calculating is described.

  The upper graph in FIG. 7 shows ON / OFF of the drive of the motor 240. The control circuit 362 assumes that the rotation of the rotary roll 290 is unstable when the motor 240 is turned off and the drive is not transmitted from the motor 240 to the rotary roll 290 via the transport roll 200. In addition, when the motor 240 is turned on and the drive from the motor 240 to the rotary roll 290 via the transport roll 200 is transmitted, the control circuit 362 assumes that the rotation of the rotary roll 290 is stable.

  Here, instead of assuming that the rotation of the rotating roll 290 is stable when the driving of the motor 240 is OFF, the driving of the motor 240 is continuously turned ON, and the electromagnetic clutch 244 transmits the driving. When the drive is transmitted from the motor 240 to the rotary roll 290, it is assumed that the rotation of the rotary roll 290 is stable and the electromagnetic clutch 244 is disconnected, and the drive transmission from the motor 240 to the rotary roll 290 is performed. The rotation of the rotary roll 290 may be unstable when the rotation is not performed.

  The middle graph in FIG. 7 shows the sensor output voltage value output from the position detection device 300.

The lower part of FIG. 7 shows a sampling data array used as a detection value. As shown in FIG. 7, the sensor output voltage value output from the position detection device 300 is sampled over the rotation roll 290 in the sampling data array obtained by sampling the rotation roll 290 over one rotation. The average value for one rotation is calculated a predetermined number of times four times with a predetermined time shift. More specifically, the average value d ₀ (0) of the sampling data array is calculated from the sampling data array 1 for one rotation acquired while the rotation of the rotary roll 290 from time 0 to t1 is stable. Similarly, the average value d ₀ (1) of the sampling data array is calculated from the sampling data array 2 acquired in the same manner.

  Here, the sampling data array for one rotation of the rotating roll 290 subsequent to the sampling data array 2 includes sampling data when the rotation of the rotating roll 290 becomes unstable. Thus, when the rotation of the rotating roll 290 becomes unstable, the calculation of the average value of the sampling data array is stopped. That is, the sampling data array including the sampling data at the time when the rotation of the rotating roll 290 is unstable is not used for calculating the average value.

  In FIG. 7, the rotation of the rotating roll 290 is unstable during the period from time t1 to t2, and the average value of the sampling data array for one rotation of the rotating roll 290 is not calculated.

In FIG. 7, the rotation of the motor 240 is turned on at time t <b> 2, the drive from the motor 240 to the rotary roll 290 is transmitted, and the rotation of the rotary roll 290 is stable. The calculation of the average value of the sampling data array for one rotation is restarted, and the control circuit 362 calculates the average value of the sampling data array for one rotation of the rotating roll 290 until the predetermined number of times becomes four. . More specifically, an average value d ₀ (2) of the sampling data array is calculated from the sampling data array 3 for one rotation acquired after time t2, and the sampling data is similarly acquired from the sampling data array 4 acquired. The average value d ₀ (3) of the array is calculated.

Further, the control circuit 362, the mean value _d 0 (0), the mean value _d 0 (1), calculates the average value of the average value _d 0 (2) and the mean value _d 0 (3), the calculated 4 The average value is further averaged to calculate the position fluctuation amount of the rotary roll 290.

FIG. 8 illustrates the principle by which the control circuit 362 calculates the displacement of the rotating roll 290 and includes the state in which the rotation of the rotating roll 290 is unstable. ing. 8 illustrates the principle of calculating the displacement of the rotating roll 290 when the rotation of the rotating roll 290 is considered to be unstable by the control circuit 362 when the rotation speed of the transport roll 200 changes. ing.
In this embodiment, it is determined whether the rotation of the rotary roll 290 is stable by using either the principle described with reference to FIG. 7 described above or the principle described below with reference to FIG. To do.

  The upper graph in FIG. 8 is a graph showing the rotational speed of the rotary roll 290 measured by the rotary encoder 320. Until the time t1, the speed of the rotary roll 290 is S1 and is constant. Between the times t1 and t2, the speed of the rotary roll 290 changes (decreases). From time t2 to t3, the speed of the rotary roll 290 is S2, which is constant. The control circuit 362 assumes that the rotation of the rotary roll 290 is stable while the rotation of the rotary roll 290 is constant from time t1 to time t2 to time t3. In addition, while the rotation of the rotary roll 290 is changing from time t1 to t2, the control circuit 362 assumes that the rotation of the rotary roll 290 is unstable.

  Here, instead of determining whether the rotation of the rotary roll 290 is stable from the rotational speed of the rotary roll 290 measured by the rotary encoder 320, for example, a storage unit (not shown) connected to the control circuit 362. The rotation profile of the rotary roll 290 stored in (2) may be used to determine whether the rotation of the rotary roll 290 is stable at each time point or whether the rotation of the rotary roll 290 is unstable.

  The middle graph in FIG. 8 shows the sensor output voltage value output from the position detection device 300.

The lower part of FIG. 8 shows a sampling data array used as a detection value. As shown in FIG. 8, the sensor output voltage value output from the position detection device 300 is sampled over the rotation roll 290 in the sampling data array obtained by sampling while the rotation roll 290 makes one rotation or more. The average value for one rotation is calculated a predetermined number of times four times with a predetermined time shift. More specifically, the average value d ₀ (0) of the sampling data array is calculated from the sampling data array 1 for one rotation acquired while the rotation of the rotary roll 290 up to time t1 is stable, and the same The average value d ₀ (1) of the sampling data array is calculated from the sampling data array 2 acquired in (1).

  Here, the sampling data array for one rotation of the rotating roll 290 subsequent to the sampling data array 2 includes sampling data when the rotation of the rotating roll 290 after time t1 becomes unstable. Thus, when the rotation of the rotating roll 290 becomes unstable, the calculation of the average value of the sampling data array is stopped. That is, the sampling data array including the sampling data at the time when the rotation of the rotating roll 290 is unstable is not used for calculating the average value.

  In FIG. 8, the rotation speed of the rotary roll 290 is changed from time t1 to time t2, and the rotation of the rotary roll 290 is considered to be unstable, and the average value of the sampling data array of the rotary roll 290 is calculated. Not done.

In FIG. 8, when the rotation of the rotating roll 290 becomes constant at time t2 and the rotation of the rotating roll 290 is stable by the control circuit 362, the average value of the sampling data array for one rotation of the rotating roll 290 is calculated. The calculation is resumed, and the control circuit 362 calculates the average value of the sampling data array for one rotation of the rotating roll 290 until the predetermined number of times reaches 4. More specifically, an average value d ₀ (2) of the sampling data array is calculated from the sampling data array 3 for one rotation acquired after time t2, and the sampling data is similarly acquired from the sampling data array 4 acquired. The average value d ₀ (3) of the array is calculated.

Further, the control circuit 362, the mean value _d 0 (0), the mean value _d 0 (1), and further calculates the average value of the average value _d 0 (2) and the mean value _d 0 (3), the calculated The average value of the four pieces is further averaged to calculate the position fluctuation amount of the rotary roll 290.

  In the method described in FIG. 7 and the method described in FIG. 8, the number of times of obtaining the average value of the data sampling array for one rotation of the rotating roll 290 is four. As in the case described with reference to FIG. 6, the number of times of obtaining the average value of the data sampling array for one rotation of the rotating roll 290 may be three, or another number.

  FIG. 9 illustrates the principle by which the control circuit 362 determines whether double feeding has occurred on the recording sheet.

  The upper part of the graph in FIG. 9 shows the output of the recording sheet detection sensor 340. When the output of the recording sheet detection sensor 340 is “1”, the recording sheet is detected and the recording sheet is nipped by the rotary roll 290. On the other hand, when the output of the recording sheet detection sensor 340 is “0”, the recording sheet is not detected and the recording sheet is not nipped by the rotary roll 290.

  The lower graph in FIG. 9 shows the output voltage value of the position detection device 300.

In FIG. 9, time t ₀ is a sampling start time when the recording sheet is not nipped by the rotary roll 290, time t ₁ is a sampling start time when the recording sheet is nipped by the rotary roll 290, and s is a sampling start interval. Where r is the rotation period of the rotating roll 290, f is the sampling interval, r ÷ f = R, and V is the output of the position detecting device 300, n in a state where the recording sheet is not nipped by the rotating roll 290 The average value of the sampling data array is expressed by the following formula.

d ₀ (0) = {V (t ₀ ) + V (t ₀ + f) +... + V (t ₀ + (R−1) × f)} ÷ R
d ₀ (1) = {V (t ₀ + s) + V (t ₀ + s + f) +... + V (t ₀ + s + (R−1) × f)} ÷ R
d ₀ (2) = {V (t ₀ + s × 2) + V (t ₀ + s × 2 + f) +... + V (t ₀ + s × 2 + (R−1) × f)} / R
・
・
・
d ₀ (n−1) = {V (t ₀ + s × (n−1)) + V (t ₀ + s × (n−1) + f) +... + V (t ₀ + s × (n−1) + (R-1) × f)} ÷ R

The average value of the m sampling data arrays in a state where the recording sheet is nipped by the rotary roll 290 is expressed by the following equation.
d ₁ (0) = {V (t ₁ ) + V (t ₁ + f) +... + V (t ₁ + (R−1) × f)} ÷ R
d ₁ (1) = {V (t ₁ + s) + V (t ₁ + s + f) +... + V (t ₁ + s + (R−1) × f)} ÷ R
d ₀ (2) = {V (t ₁ + s × 2) + V (t ₁ + s × 2 + f) +... + V (t ₁ + s × 2 + (R−1) × f)} / R
・
・
・
d ₁ (m−1) = {V (t ₀ + s × (m−1)) + V (t ₀ + s × (m−1) + f) +... + V (t ₀ + s × (m−1) + (R-1) × f)} ÷ R

Therefore, the further average value of the average values of the n sampling data arrays in a state where the recording sheet is not nipped by the rotary roll 290 is expressed by the following equation.
d ₀ = {d ₀ (0) + d ₀ (1) + d ₀ (2) +... + d ₀ (n−1)} ÷ n

Further, a further average value of the average values of the m sampling data arrays in a state where the recording sheet is nipped by the rotary roll 290 is expressed by the following equation.
d ₁ = {d ₁ (0) + d ₁ (1) + d ₁ (2) +... + d ₁ (m−1)} ÷ m

That is, the thickness of the recording sheet, the mean value d ₀ in a state where the recording sheet is not nipped by the rotating rolls 290, a difference of mean values d ₁ in a state where the recording sheet is nipped by the rotating rolls 290, It becomes like the following formula.
Δd = | d ₀ −d ₁ |

Therefore, in the double feed determination calculation unit, the thickness of the recording sheet conveyed to the Kth sheet is Δd _K , and the average thickness of the past L recording sheets is Δd _L (= (Δd _K−L + Δd _{K− L + 1} +... + Δd _K−1 ) ÷ (K−L)) and the double feed determination magnification is α (1 <α <2), it is determined that double feed has occurred when the following equation is satisfied. To do.
Δd _K ≧ Δd _L × α

  Next, the control in the control part 360 of the position detection apparatus 300 in this embodiment is demonstrated.

FIG. 10 is a flowchart illustrating a processing method performed by the control circuit 362.
First, it is determined whether or not the recording sheet detection sensor 340 detects a recording sheet (S100). In the case of NO in S100, for example, a sheet remaining error is displayed on a display unit (not shown) such as a liquid crystal display panel provided in the image forming apparatus 10 (S101), and the process is terminated.

  Next, in the case of YES in S100, rotation of the transport roll 200 is started (S102). For example, timer0, which is a timer incorporated in the control circuit 362, is initialized to 0 (S104).

  Next, it is determined whether or not timer0 has reached the sampling start time (S106). If NO in S106, 1 is added to timer0 (S107), and S106 is executed again.

If YES in S106, the position detection device 300 measures the displacement amount d ₀ (displacement amount for ₀ recording sheet) when the recording sheet is not nipped by the rotary roll 290 (S108).

  Next, it is determined whether or not the recording sheet detection sensor 340 detects a recording sheet (S110). If NO in S110, the process of S110 is repeated.

  If YES in S110, a predetermined timer timer0 is initialized to 0 (S112).

  Next, it is determined whether timer0 has reached the sampling start time (S114). If NO in S114, 1 is added to timer0 (S115), and S114 is executed again.

In the case of YES in S114, the position detection device 300 measures the displacement d ₁ (sheet transport first displacement) in a state where the recording sheet is nipped by the rotary roll 290, and the recording sheet thickness ( _{Δd L = Δd 1 = d 1} -d 0) to calculate the (S116).

Next, it is determined whether or not the job is completed (S118). If YES in S118 _is, d 0, resets the _{d 1} (S119) and ends the process.

  If NO in S118, it is determined whether or not the recording sheet detection sensor 340 detects a recording sheet (S120). If NO in S120, the process in S118 is repeated.

  Next, in the case of YES in S120, timer 0 which is a predetermined timer is initialized to 0 (S122).

  Then, it is determined whether timer0 has reached the sampling start time (S124). In the case of NO in S124, 1 is added to timer0 (S125), and S124 is executed again.

Next, in the case of YES in S124, the position detection device 300 executes a displacement amount d ₀ (displacement correction for 0 recording sheet) when the recording sheet is not nipped by the rotary roll 290 (S126).

  Then, it is determined whether or not the recording sheet detection sensor 340 detects a recording sheet (S128). If NO in S128, the process in S128 is repeated.

  Next, in the case of YES in S128, a predetermined timer timer0 is initialized to 0 (S130).

  Then, it is determined whether timer0 has reached the sampling start time (S132). If NO in S132, 1 is added to timer0 (S133), and S132 is executed again.

Next, in the case of YES in _S <b> 130, the displacement d ₁ (sheet transport Nth displacement (Δd _N = | d ₁ −d ₀ |) in a state where the recording sheet is nipped by the rotary roll 290 in the position detection device 300. )) Is measured (S134).

Then, it is determined whether d _N is equal to or smaller than α × Δd _L (S136). In the case of NO in S136, it is determined that it is double feed (S137), stops the job _(S138), d 0, resets the _{d 1} (S139) and ends the process.

Next, it is determined whether or not the recording sheet is transported for the second time (S140). If YES in S140 is, [Delta] d ₁ is equal to or in alpha × [Delta] d ₂ below (S141). In the case of NO in S140, determines that it is overlapped feeding first conveyance of the recording sheet (S142), stops the job _(S143), it resets the _d 0, d ₁ (S144) the process ends To do. If YES in S139, the next S144 is executed.

Then, it is determined whether or not the job is completed (S146). In the case of YES in S146 _resets the _d 0, d ₁ (S147) and ends the process.

Then, in the case of NO in S146 updates the [Delta] d _L to the average value of the past L recording sheets thickness _{Δd N-L + 1 Δ~Δd N} (S148).

  Then, it is determined whether or not the recording sheet detection sensor 340 detects a recording sheet (S150). If NO in S150, the process of S150 is repeated. If YES in S150, the process returns to S122.

  The flowchart can be a computer program.

  As described above, the image forming apparatus 10 is controlled to stop the job when the recording sheet is double-feeded. However, the image forming apparatus 10 is not limited to the control to stop the job. In this case, it is only necessary to control at least one of the image forming unit 32 and the paper feeding device 150 when double feeding occurs in the recording sheet.

  For example, when the double feeding of the recording sheet is detected, the image formation by the image forming unit 32 is immediately terminated, and the image formation is performed on the recording sheet conveyed before the recording sheet in which the double feeding is detected. After the process is completed, the image forming unit 32 may be controlled to stop.

  Further, when double feeding of recording sheets is detected, control may be performed so that the recording sheet in which double feeding is detected is discharged to the discharge tray 62 without forming an image.

  Further, as described above, in the image forming apparatus 10, the control unit 360 controls at least one of the image forming unit 32 and the paper feeding device 150 when double feeding occurs in the recording sheet. Instead of this, or in addition to this, the control unit 360 may control the image forming conditions of the image forming unit 32 based on the measured thickness of the recording sheet. For example, the control unit 360 may control the primary transfer bias applied to the primary transfer roll 50 included in the image forming unit 32 based on the measured thickness of the recording sheet. Further, for example, the controller 360 may control the amount of heat generated by the fixing device 60 based on the measured thickness of the recording sheet.

Next, the image forming apparatus 10 according to the second embodiment will be described.
In the first embodiment described above, the control unit 360 acquires the detection value detected by the position detection device 300 over one rotation of the rotary roll 290 at a predetermined time interval, and among the acquired detection values The average value of the detected values for one rotation of the rotating roll 290 was calculated a predetermined number of times while shifting the predetermined time interval, and the calculated average value of the predetermined number of times was further averaged to calculate the position fluctuation amount of the rotating roll 290. When the rotation of the rotary roll 290 becomes unstable, the control unit 360 stops calculating the average value for one rotation of the rotary roll 290 including the detected value at that time, and after the rotation of the rotary roll 290 is stabilized The calculation of the average value for one rotation of the rotary roll 290 was resumed, and the average value for one rotation of the rotary roll 290 was calculated until a predetermined number of times was reached.

  On the other hand, in the image forming apparatus 10 according to the second embodiment, similarly to the image forming apparatus 10 according to the first embodiment, the control unit 360 detects the detection value detected by the position detection apparatus 300. Is obtained while the rotating roll 290 makes one rotation or more at a predetermined time interval, and the average value of the detected values for one rotation of the rotating roll 290 among the acquired detection values is shifted a predetermined number of times. The calculated average value of the predetermined number of times is further averaged to calculate the position fluctuation amount of the rotary roll 290. Further, in the image forming apparatus 10 according to the second embodiment, unlike the image forming apparatus 10 according to the first embodiment described above, the control unit 360 is configured to change the rotation speed of the rotary roll 290 when A detection value for one rotation of the rotary roll 290 is specified using an output from the rotary encoder 320, and a detection value for one rotation of the specified rotary roll 290 is detected as a detection value at which the rotation speed of the rotary roll 290 is constant. And the average value for one rotation of the rotary roll 290 is calculated.

  The image forming apparatus 10 according to the second embodiment is the same as that of the first embodiment except that the principle for calculating the positional fluctuation amount of the rotary roll 290 as described above is different. Hereinafter, the principle of calculating the position fluctuation amount of the second rotating roll 290 will be described.

  11 and 12 show the principle that the control circuit 362 calculates the displacement of the rotating roll 290 in the second embodiment, and particularly when the rotating speed of the rotating roll 290 changes, the displacement of the rotating roll 290 is changed. The principle of calculating is described. The principle of the rotating roll 290 when the rotating speed of the rotating roll 290 does not change as described above is the same as that of the first embodiment described above (see FIG. 6).

  The upper graph in FIG. 11 is a graph showing the rotational speed of the rotary roll 290 measured by the rotary encoder 320. Until the time t1, the speed of the rotary roll 290 is S1 and is constant. Between the times t1 and t2, the speed of the rotary roll 290 changes (decreases). From time t2 to t3, the speed of the rotary roll 290 is S2, which is constant.

  Here, instead of measuring the rotational speed of the rotary roll 290 by the rotary encoder 320, for example, the rotational profile of the rotary roll 290 is stored in advance in a storage unit (not shown) connected to the control circuit 362, The speed of the rotation profile at each time point may be referred to from the rotation profile.

  The middle graph in FIG. 11 shows the sensor output voltage value output from the position detection device 300.

In the lower part of FIG. 11, a sampling data array used as a detection value is shown. As shown in FIG. 11, the sensor output voltage value output from the position detection device 300 is sampled over the rotation roll 290 in the sampling data array obtained by sampling while the rotation roll 290 makes one rotation or more. The average value for one rotation is calculated a predetermined number of times four times with a predetermined time shift. More specifically, from the sampling data array 1, the sampling data array 2, the sampling data array 3, and the sampling data array 4 corresponding to one rotation of the rotating roll 290, the average value d ₀ (0), the average value of the sampling data array d ₀ (1), average value d ₀ (2), and average value d ₀ (3) are respectively calculated.

  Here, in the first embodiment described above, the average value of the sampling data array including the sampling data at the time when the rotational speed of the rotary roll 290 after the time t1 has changed is not calculated. On the other hand, in the second embodiment, the average value of the sampling data array including the data at the time when the rotational speed of the rotary roll 290 changes is also calculated. That is, the sampling data array 1 and the sampling data array 2 do not include sampling data at the time when the rotation speed of the rotating roll 290 changes, but the sampling data array 3 and the sampling data array 4 are the rotations of the rotating roll 290. Contains sampling data at the time the speed changes.

  Further, in the second embodiment, the control circuit 362 specifies sampling data for one rotation of the rotary roll 290 using the output from the rotary encoder 320. For this reason, even if the rotational speed of the rotating roll 290 changes during sampling, the sampling data array for one rotation of the rotating roll 290 can be specified.

  As shown in FIG. 12, in the second embodiment, the control circuit 362 uses the sampling data array for one rotation of the rotating roll 290 and the rotation pulse signal of the rotating roll 290 to keep the rotation speed constant. Conversion processing is performed on the output of the position detection device 300 so as to obtain a sampling data array. For this reason, even if the rotational speed of the rotating roll 290 is changing as in the sampling data array 3 and the sampling data array 4, the displacement of the rotating roll 290 can be detected. The upper graph in FIG. 12 shows the output of the position detection device 300 that has been output from the position detection device 300 and has not been converted, and the lower graph in FIG. 12 shows the result after the above conversion processing has been performed. 5 is a graph showing an output from the position detection device 300.

The average value d ₀ (0), average value d ₀ (1), average value d ₀ (2), and average value d ₀ (3) calculated as described above are further averaged to obtain a control circuit. 362 calculates the position fluctuation amount of the rotary roll 290.

  FIG. 13 shows a first modification of the position detection device 300.

  In the position detection apparatus 300 included in the image forming apparatus 10 according to the first embodiment and the image forming apparatus 10 according to the second embodiment, the actuator 302 directly contacts the rotating roll shaft 294, and the rotating roll shaft It came to follow 294. On the other hand, in the first modification, bearings 296 and 296 are attached to the rotary roll shaft 294, and a holder 298 is attached so as to cover the bearings 296 and 296. The actuator 302 is attached to the holder 298. It comes to contact.

  Since the holder 298 is attached to the rotary roll shaft 294 via the bearings 296, 296, the holder 298 does not rotate even if the rotary roll shaft 294 rotates. On the other hand, when the rotating roll body 292 and the rotating roll shaft 294 move up and down, the holder 298 moves up and down together with the rotating roll body 292 and the rotating roll shaft 294. When the holder 298 moves up and down, the actuator 302 is displaced so as to rotate following the 298, and the angle of the displacement is detected by the angle sensor 304.

  According to this modified example of the position detection device 300, the holder 298 does not rotate following the rotary roll shaft 294 and the like, so that frictional wear is unlikely to occur in the actuator 302.

FIG. 14 shows a second modification of the position detection device 300.
In the second modification of the position detection device 300, the bearings 296 and 296 are mounted on the rotary roll shaft 294 and cover the top of the bearings 296 and 296, as in the first modification of the position detection device 300 described above. The holder 298 is attached as described above, and the actuator 302 comes into contact with the holder 298.

  Further, in the second modification of the position detection device 300, the actuator 302 is formed in an L shape composed of a horizontal portion and a vertical portion, and the actuator swing shaft 306 is supported so that the actuator 302 swings. Has been. The second modification of the position detection apparatus 300 includes a photo interrupter 314 including a light emitting element 308 and a light receiving element 310. The photointerrupter 314 changes the amount of light received by the light receiving element 310 when the actuator 302 swings.

  FIG. 15 is a graph illustrating the first embodiment of the present invention, in which the thickness of the recording sheet is measured using the present invention.

  The upper part of the graph in FIG. 15 shows the output of the recording sheet detection sensor 340. When the output of the recording sheet detection sensor 340 is “1”, the recording sheet is detected and the recording sheet is nipped by the rotary roll 290. On the other hand, when the output of the recording sheet detection sensor 340 is “0”, the recording sheet is not detected and the recording sheet is not nipped by the rotary roll 290. From time t0 to t3, the recording sheet is nipped by the rotating roll, and from time t3 to t6, the recording sheet is not nipped by the sheet.

  The middle graph in FIG. 15 shows the rotational speed of the rotating roll 290 measured by the rotary encoder 320. Until the time t1, the speed of the rotary roll 290 is S1, which is constant. Between the times t1 and t2, the speed of the rotary roll 290 changes (decreases). During the period from time t2 to t4, the speed of the rotary roll 290 is S2, which is constant. Between time t4 and time t5, the speed of the rotating roll 290 changes (rises). After the time t5, the speed of the rotary roll 290 is S1, which is constant. While the speed is constant, the control circuit 362 assumes that the rotation of the rotary roll 290 is stable. On the other hand, while the speed of the rotary roll 290 is changing, the control circuit 362 assumes that the rotation of the rotary roll is unstable.

  The lower graph in FIG. 15 shows the output voltage value of the position detection device 300.

In FIG. 15, time t ₀ is the sampling start time when the recording sheet is nipped by the rotating roll 290, and time t ₃ is the sampling start time when the recording sheet is nipped by the rotating roll 290.

  A data array (sampling data array) is shown below the three graphs in FIG. Time t0 to t1 is a period in which the recording sheet is nipped and the speed of the rotary roll 290 is constant. During this period, the data array D01 and the data array D02 for one rotation of the rotating roll 290 are acquired by shifting a predetermined time, and the average values thereof are calculated as d01 and d02. In this embodiment, the calculated average value d01 of the data array D01 is 5.4, and the calculated average value d02 of the data array D02 is 5.4.

  During the period from time t1 to t2, the rotation of the rotary roll 290 is changed, so that the data array is not acquired. Further, the average value of the data array including the data from time t1 to t2 is not calculated.

  The period from time t2 to t3 is a period in which the recording sheet is nipped and the speed of the rotary roll 290 is constant. During this period, the data array D03 for one rotation of the rotating roll 290 is acquired, and the average value d03 of the acquired data array D03 is calculated. In this embodiment, the average value d03 of the calculated data array D03 is 5.4.

The average value pos0 of d01, d02, and d03, which is the average value of the data array for one rotation of the rotary roll 290 when the recording sheet calculated as described above is not nipped, is further calculated. In this example,
pos0 = (5.4 + 5.5 + 5.5) /3=5.43.

  From time t3 to t4 is a period in which the recording sheet is nipped and the rotation of the rotary roll 290 is constant. During this period, the data array D11 is acquired, and the average value d11 of the data array D11 for one rotation of the rotating roll 290 is calculated. In this embodiment, the calculated average value d11 of the data array D11 is 2.4.

  From time t4 to t5, the data array is not acquired because the speed of the rotating roll 290 changes. In addition, the average value of the data array including data between time t4 and t5 is not calculated.

  Time t5 to t6 is a period in which the recording sheet is not nipped and the rotation of the rotary roll 290 is constant. During this period, the data array D12 and the data array D13 for one rotation of the rotating roll 290 are acquired by shifting a predetermined time, and the average values d12 and d13 are calculated. In this embodiment, the calculated average value d12 of the data array D12 is 2.2, and the calculated average value d13 of the data array D13 is 2.3.

The average value pos1 of d11, d12, and d13, which is the average value of the data array for one rotation of the rotary roll 290 when the recording sheet calculated as described above is not nipped, is further calculated. In this example,
pos1 = (2.4 + 2.2 + 2.3) /3=2.3.

The recording sheet thickness Δpos is calculated as the difference between pos0 and pos1 calculated as described above. In this embodiment,
Δd = | pos0−pos1 | = | 5.43−2.3 | = 2.13.

  FIG. 16 is a grab illustrating a second embodiment of the present invention, in which an embodiment for measuring the thickness of a recording sheet using the present invention is described.

  The upper part of the graph in FIG. 16 shows the output of the recording sheet detection sensor 340. When the output of the recording sheet detection sensor 340 is “1”, the recording sheet is detected and the recording sheet is nipped by the rotary roll 290. On the other hand, when the output of the recording sheet detection sensor 340 is “0”, the recording sheet is not detected and the recording sheet is not nipped by the rotary roll 290. From time t0 to t3, the recording sheet is nipped by the rotating roll, and from time t3 to t6, the recording sheet is not nipped by the sheet.

  The middle graph in FIG. 16 shows the rotational speed of the rotary roll 290 measured by the rotary encoder 320. Until the time t1, the speed of the rotary roll 290 is S1, which is constant. Between the times t1 and t2, the speed of the rotary roll 290 changes (decreases). During the period from time t2 to t4, the speed of the rotary roll 290 is S2, which is constant. Between the times t4 and t5, the speed of the rotary roll 290 changes (increases). After the time t5, the speed of the rotary roll 290 is S1, which is constant.

  The lower graph in FIG. 16 shows the output voltage value of the position detection device 300.

  In FIG. 16, time t0 is the sampling start time when the recording sheet is nipped by the rotating roll 290, and time t3 is the sampling start time when the recording sheet is nipped by the rotating roll 290.

  A data array (sampling data array) is shown below the three graphs in FIG. From time t0 to t3, the recording sheet is nipped. During this period, the data array D01, the data array D02, and the data array D03 for one rotation of the rotating roll 290 are acquired by shifting a predetermined time, and the average values thereof are calculated as d01, d02, and d03. Here, the data in the data array D01 consists only of data acquired from time t0 to time t1 when the speed of the rotary roll 290 is constant.

  On the other hand, the data arrays D02 and D03 include data acquired from time t1 to time t2, which is a period during which the rotation of the rotating roll 290 changes. For the data array D02 and the data array D03, the control circuit 362 uses the data array for one rotation of the rotating roll 290 and the rotation pulse signal of the rotating roll 290 so that the data array has a constant rotation speed. In addition, the average values d01 and d02 are calculated after the conversion processing is performed on the output of the position detection apparatus 300.

  In this second embodiment, the average value d01 of the output data array D01 is 5.4, the average value d02 of the calculated data array D02 is 5.5, and the average of the calculated data array D03 The value of d03 is 5.4.

The average value pos0 of d01, d02, and d03, which is the average value of the data array for one rotation of the rotary roll 290 when the recording sheet calculated as described above is not nipped, is further calculated. In this example,
pos0 = (5.4 + 5.5 + 5.4) /3=5.43.

  From time t3 to time t6, the recording sheet is not nipped. During this period, the data array D11, the data array D12, and the data array D13 for one rotation of the rotating roll 290 are acquired by shifting a predetermined time, and the average values thereof are calculated as d11, d12, and d13. Here, the data in the data array D11 consists only of data acquired during the time t3 to t4 when the speed of the rotary roll 290 is constant.

  On the other hand, the data arrays D12 and D13 include data acquired from time t4 to t5, which is a period in which the rotation of the rotary roll 290 changes. For the data array D12 and the data array D13, the control circuit 362 uses the data array for one rotation of the rotating roll 290 and the rotation pulse signal of the rotating roll 290 so that the data array has a constant rotation speed. In addition, the average values d11 and d12 are calculated after converting the output of the position detection device 300.

  In this second embodiment, the average value d11 of the output data array D11 is 2.4, the average value d12 of the calculated data array D12 is 2.2, and the average of the calculated data array D13 The value of d03 is 2.3.

The average value pos1 of d11, d12, and d13, which is the average value of the data array for one rotation of the rotary roll 290 when the recording sheet calculated as described above is not nipped, is further calculated. In this example,
pos1 = (2.4 + 2.2 + 2.3) /3=2.3.

The recording sheet thickness Δpos is calculated as the difference between pos0 and pos1 calculated as described above. In this embodiment,
Δd = | pos0−pos1 | = | 5.43−2.3 | = 2.13.

  As described above, the present invention can be applied to a thickness measurement device, a multifeed detection device, and an image forming apparatus. Here, examples of the image forming apparatus include a copying machine, a printer such as a laser printer and an ink jet printer, and a facsimile apparatus. Examples of the image forming apparatus include an apparatus that performs at least two of a copying function, a printer function, and a facsimile transmission / reception function.

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus 30 ... Image output part 32 ... Image forming part 150 ... Paper feeding apparatus 200 ... Conveyance roll 240 ... Motor 244 ... Electromagnetic clutch 290 ... Rotation Roll 300 ... Position detecting device 302 ... Actuator 304 ... Angle sensor 360 ... Control unit

Claims (16)

A transport member that rotates in contact with the transported body and transports the transported body;
Position detecting means for detecting a position of the transport member in a direction in contact with the transported body;
An acquisition means for acquiring a detection value detected by the position detection means over a period of one rotation or more of the conveying member at a predetermined time interval;
Control means for controlling the acquisition means in accordance with a transport state in which the transport member transports the transported body;
Conveying member position variation measuring device.   2. The conveyance member position variation measuring device according to claim 1, wherein when the rotation speed of the conveyance member changes, the control unit stops acquisition of a detection value by the acquisition unit.   The conveyance member position fluctuation amount measuring apparatus according to claim 2, wherein the control unit restarts the acquisition of the detection value by the acquisition unit when the rotation speed of the conveyance member becomes constant. A driving source for transmitting driving to the conveying member;
2. The conveyance member position variation measuring device according to claim 1, wherein when the drive transmission from the drive source to the conveyance member is cut off, the control unit stops acquisition of a detection value by the acquisition unit.   5. The conveyance member position fluctuation amount measuring apparatus according to claim 4, wherein the control unit resumes acquisition of the detection value by the acquisition unit when drive transmission from the drive source to the conveyance member is resumed. A transport member that rotates in contact with the transported body and transports the transported body;
Position detecting means for detecting a position of the transport member in a direction in contact with the transported body;
An acquisition means for acquiring a detection value detected by the position detection means over a period of one rotation or more of the conveying member at a predetermined time interval;
Conversion means for converting the detection value acquired by the acquisition means so as to be a detection value at which the rotation speed of the conveyance is constant when the rotation speed of the conveyance member changes;
Conveying member position variation measuring device. A rotation speed measuring means for measuring the rotation speed of the conveying member;
The conveyance member position variation measuring device according to claim 6, wherein the conversion unit converts the detection value acquired by the acquisition unit using the rotation speed of the conveyance member measured by the rotation speed measurement unit.   The conveyance member position variation measuring device according to claim 6, wherein the conversion unit converts the detection value acquired by the acquisition unit based on information on a rotation speed of the conveyance member stored in advance. A transport member that rotates in contact with the transported body and transports the transported body;
Position detecting means for detecting a position of the transport member in a direction in contact with the transported body;
An acquisition means for acquiring a detection value detected by the position detection means over a period of one rotation or more of the conveying member at a predetermined time interval;
Thickness for calculating the thickness of the transported body from the difference between the position variation amount of the transport member when the transported body is transported and the position variation amount of the transport member when the transported body is not transported Computing means;
Control means for controlling the acquisition means in accordance with a transport state in which the transport member transports the transported body;
A thickness measuring device. A transport member that rotates in contact with the transported body and transports the transported body;
Position detecting means for detecting a position of the transport member in a direction in contact with the transported body;
An acquisition means for acquiring the detection value detected by the position detection means over a period of one rotation or more of the conveying member at a predetermined time interval;
Conversion means for converting the detection value acquired by the acquisition means to a detection value at which the rotation speed of the conveyance is constant when the rotation speed of the conveyance member changes;
Thickness for calculating the thickness of the transported body from the difference between the position variation amount of the transport member when the transported body is transported and the position variation amount of the transport member when the transported body is not transported Computing means;
A thickness measuring device. A transport member that rotates in contact with the transported body and transports the transported body;
Position detecting means for detecting a position of the transport member in a direction in contact with the transported body;
An acquisition means for acquiring a detection value detected by the position detection means over a period of one rotation or more of the conveying member at a predetermined time interval;
A thickness calculating means for calculating a thickness of the transported body from a position variation amount of the transport member;
dn is the thickness of the N-th (N ≧ 2) integer transported body calculated by the thickness calculating means,
d0 is an average value of the thicknesses of at least one transported body up to the (N-1) th sheet calculated by the thickness calculation means,
a multi-feed determining unit that determines that multi-feed has occurred in the conveyed object when dn ≧ d0 × α (1 <α <2) is satisfied;
Control means for controlling the acquisition means in accordance with a transport state in which the transport member transports the transported body;
A double feed detection device. A transport member that rotates in contact with the transported body and transports the transported body;
Position detecting means for detecting a position of the transport member in a direction in contact with the transported body;
An acquisition means for acquiring a detection value detected by the position detection means over a period of one rotation or more of the conveying member at a predetermined time interval;
Conversion means for converting the detection value acquired by the acquisition means to a detection value at which the rotation speed of the conveyance is constant when the rotation speed of the conveyance member changes;
A thickness calculating means for calculating a thickness of the transported body from a position variation amount of the transport member;
dn is the thickness of the N-th (N ≧ 2) integer transported body calculated by the thickness calculating means,
d0 is an average value of the thicknesses of at least one transported body up to the (N-1) th sheet calculated by the thickness calculation means,
a multi-feed determining unit that determines that multi-feed has occurred in the conveyed object when dn ≧ d0 × α (1 <α <2) is satisfied;
A double feed detection device. A thickness measuring device for measuring the thickness of the conveyed object;
An image forming unit that forms an image on a transported body whose thickness is measured by the thickness measuring device;
An image forming condition control unit that controls image forming conditions of the image forming unit based on the thickness of the transported body measured by the thickness measuring device;
Have
The thickness measuring device includes:
A transport member that rotates in contact with the transported body and transports the transported body;
Position detecting means for detecting a position of the transport member in a direction in contact with the transported body;
An acquisition means for acquiring a detection value detected by the position detection means over a period of one rotation or more of the conveying member at a predetermined time interval;
Thickness for calculating the thickness of the transported body from the difference between the position variation amount of the transport member when the transported body is transported and the position variation amount of the transport member when the transported body is not transported Computing means;
Control means for controlling the acquisition means in accordance with a transport state in which the transport member transports the transported body;
An image forming apparatus. A thickness measuring device for measuring the thickness of the conveyed object;
An image forming unit that forms an image on a transported body whose thickness is measured by the thickness measuring device;
An image forming condition control unit that controls image forming conditions of the image forming unit based on the thickness of the transported body measured by the thickness measuring device;
Have
The thickness measuring device includes:
A transport member that rotates in contact with the transported body and transports the transported body;
Position detecting means for detecting a position of the transport member in a direction in contact with the transported body;
An acquisition means for acquiring a detection value detected by the position detection means over a period of one rotation or more of the conveying member at a predetermined time interval;
Conversion means for converting the detection value acquired by the acquisition means to a detection value at which the rotation speed of the conveyance is constant when the rotation speed of the conveyance member changes;
Thickness for calculating the thickness of the transported body from the difference between the position variation amount of the transport member when the transported body is transported and the position variation amount of the transport member when the transported body is not transported Computing means;
An image forming apparatus. An image forming unit that forms an image on a transported body;
A transport device for transporting a transported object to the image forming unit;
A double feed detection device that detects whether or not double feed is occurring in the transported object being transported by the transport device;
Control means for controlling at least one of the image forming unit and the transport device based on a detection result by the double feed detection device;
Have
The multifeed detector is
A transport member that rotates in contact with the transported body and transports the transported body;
Position detecting means for detecting a position of the transport member in a direction in contact with the transported body;
An acquisition means for acquiring a detection value detected by the position detection means over a period of one rotation or more of the conveying member at a predetermined time interval;
Conversion means for converting the detection value acquired by the acquisition means to a detection value at which the rotation speed of the conveyance is constant when the rotation speed of the conveyance member changes;
A thickness calculating means for calculating a thickness of the transported body from a position variation amount of the transport member;
dn is the thickness of the N-th (N ≧ 2) integer transported body calculated by the thickness calculating means,
d0 is an average value of the thicknesses of at least one transported body up to the (N-1) th sheet calculated by the thickness calculation means,
a multi-feed determining unit that determines that multi-feed has occurred in the conveyed object when dn ≧ d0 × α (1 <α <2) is satisfied;
An image forming apparatus. An image forming unit that forms an image on a transported body;
A transport device for transporting a transported object to the image forming unit;
A double feed detection device that detects whether or not double feed is occurring in the transported object being transported by the transport device;
Control means for controlling at least one of the image forming unit and the transport device based on a detection result by the double feed detection device;
Have
The multifeed detector is
A transport member that rotates in contact with the transported body and transports the transported body;
Position detecting means for detecting a position of the transport member in a direction in contact with the transported body;
An acquisition means for acquiring a detection value detected by the position detection means over a period of one rotation or more of the conveying member at a predetermined time interval;
Conversion means for converting the detection value acquired by the acquisition means to a detection value at which the rotation speed of the conveyance is constant when the rotation speed of the conveyance member changes;
A thickness calculating means for calculating a thickness of the transported body from a position variation amount of the transport member;
dn is the thickness of the N-th (N ≧ 2) integer transported body calculated by the thickness calculating means,
d0 is an average value of the thicknesses of at least one transported body up to the (N-1) th sheet calculated by the thickness calculation means,
a multi-feed determining unit that determines that multi-feed has occurred in the conveyed object when dn ≧ d0 × α (1 <α <2) is satisfied;
An image forming apparatus.

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