JP6459449B2 - Sheet conveying apparatus, document reading apparatus, and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet conveying apparatus, a document reading apparatus including the sheet conveying apparatus, and an image forming apparatus.

For example, in an electrophotographic image forming apparatus, an image is formed by transferring a toner image formed on the surface of a photoconductor onto a sheet such as transfer paper conveyed from a paper feeding unit.
The paper feed unit feeds the uppermost sheet (hereinafter referred to as “preceding sheet”) of the bundle of recording sheets stored in the paper feed cassette with a pickup roller. There is a possibility that the second sheet of the recording sheet bundle may be carried, and the carried sheet (hereinafter referred to as “next sheet”) is rolled up in the winding portion and separated from the preceding sheet. Is done.

Usually, the winding unit is rolled by a paper feeding roller that is rotationally driven in the forward direction in order to convey the sheet in the sheet conveying direction, and a winding roller that is given a rotational force in a direction opposite to the forward direction via a torque limiter. It is configured by forming a nip portion.
As a result, the fed next sheet receives a force (frictional force) pushed back in the opposite direction from the rolling roller, so in most cases it stops at the rolling nip portion and only the preceding sheet is conveyed downstream.

However, if the surface of the rolling roller is worn and deteriorated, the coefficient of friction with the sheet becomes small, the next sheet cannot be sufficiently wound, and in the worst case, paper jams occur frequently due to double feeding, and jam processing Therefore, it is desirable to determine the life of the roller and replace it at an appropriate time.
Conventionally, as a method of determining the replacement timing of the roller, the number of fed sheets is counted, and it is based on whether or not the number has reached a predetermined number. There is also a method of measuring and determining that the diameter has deteriorated when the diameter becomes smaller than a certain value (for example, see Patent Document 1).

JP-A-8-324814 JP-A-8-85671 JP 2010-208795 A

However, when judging based on the number of sheets supplied, the specified number of sheets is not necessarily specified depending on the type of sheet to be fed (plain paper, cardboard, recycled paper, high-quality paper, etc.) and the usage environment (temperature / humidity). In some cases, the paper-rolling roller still has sufficient paper-rolling capacity even when the number of papers exceeds the limit, or paper jams frequently occur before the specified number of papers is reached.
Also, when measuring and determining the diameter of the roller, a high-precision range sensor such as a laser displacement sensor must be used, and the change in the roller diameter that can be detected is detected on the peripheral surface of the roller. It does not always reflect subtle changes in the coefficient of friction.

As described above, the problem can occur in all apparatuses having a sheet conveying mechanism that draws out a sheet from a sheet bundle and rolls the sheet at a separating section.
The present invention has been made in view of the above circumstances, and provides a sheet conveying apparatus, a document reading apparatus, and an image forming apparatus that can accurately detect the degree of deterioration of a separating member in a sheet separating section. It is an object.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a sheet conveying device that feeds and conveys a sheet from a sheet storage unit, wherein a sheeting member is brought into contact with a peripheral surface of a sheet feeding roller to form a sheeting nip unit. Forming a sheet, and the sheet fed from the sheet storage unit is rolled and passed through the nip portion, the sheeting unit that scatters the preceding sheet and the next sheet, and the leading edge of the next sheet that has been moved by the sheeting unit and stopped moving A protrusion amount detecting means for detecting a protrusion amount from the whirling nip portion, a determining means for determining a deterioration state of the separating member based on the protrusion amount detected by the protrusion amount detecting means, and a deterioration determined by the determining means Warning means for issuing a warning according to the state , wherein the determination means determines that the rolled member has deteriorated when the protrusion amount of the next sheet exceeds a first threshold, and the warning means捌A counter that warns that the member should be replaced and counts the number of sheets conveyed is accumulated, and the determination unit determines that the protrusion amount is less than the first value before the count value by the counter reaches a predetermined value. When the threshold value of 1 is exceeded, it is determined that the main cause of the rolling failure is paper dust attached to the surface of the winding member that contacts the paper feed roller, and the warning means detects the paper dust on the peripheral surface of the rolling roller. It is characterized by warning that it should be cleaned .
According to a second aspect of the present invention, there is provided a sheet conveying apparatus that feeds and conveys a sheet from a sheet storage unit, wherein a sheeting member is brought into contact with a peripheral surface of a sheet feeding roller to form a sheeting nip portion, A sheet rolled out from the storage unit is passed through the nip part, and the sheet is passed through the preceding sheet and the next sheet, and from the sheeting nip part at the leading edge of the next sheet that has been stopped by the sheeting means. A protrusion amount detecting means for detecting the protrusion amount of the first member, a determining means for determining the deterioration state of the whirling member based on the protrusion amount detected by the protrusion amount detecting means, and a warning according to the deterioration state determined by the determining means Warning means for issuing a warning, wherein the determination means determines that the rolling member has deteriorated when the amount of protrusion of the next sheet exceeds a first threshold, and the warning means replaces the rolling member. Should And when the protrusion amount exceeds a second threshold value that is smaller than the first threshold value, the determination unit determines that the timing for replacing the rolling member comes after feeding the predetermined number of sheets, and the warning unit Is characterized by a warning to that effect.
According to a third aspect of the present invention, there is provided a sheet conveying apparatus that feeds and conveys a sheet from a sheet storage unit, wherein a sheeting member is brought into contact with a peripheral surface of a sheet feeding roller to form a sheeting nip portion, A sheet rolled out from the storage unit is passed through the nip part, and the sheet is passed through the preceding sheet and the next sheet, and from the sheeting nip part at the leading edge of the next sheet that has been stopped by the sheeting means. A protrusion amount detecting means for detecting the protrusion amount of the first member, a determining means for determining the deterioration state of the whirling member based on the protrusion amount detected by the protrusion amount detecting means, and a warning according to the deterioration state determined by the determining means Warning means that emits an image, and the protrusion amount detection means captures an image of a sheet surface in a predetermined range including a position corresponding to the nip portion in the sheet conveying direction using an area sensor. Imaging means, and a calculation means for detecting the position of the leading edge of the next sheet based on the image data obtained by the imaging means and calculating the amount of protrusion of the leading edge of the next sheet from the nip portion, The image pickup means is arranged to pick up an image of a range shifted in the main scanning direction by a predetermined distance from the turning member in the turning means, and the protrusion amount detection means is image data obtained by the image pickup means. Based on the distance of the leading edge of the next sheet rolled by the rolling means with respect to the main scanning direction, and based on the distance between the imaging means and the rolling member in the main scanning direction and the amount of inclination, It is characterized in that the amount of projection of the next sheet from the winding nip portion in the central portion in the axial direction is obtained.
According to a fourth aspect of the present invention, there is provided a sheet conveying apparatus that feeds and conveys a sheet from a sheet storage unit, wherein a sheeting member is brought into contact with a peripheral surface of a sheet feeding roller to form a sheeting nip portion, A sheet rolled out from the storage unit is passed through the nip part, and the sheet is passed through the preceding sheet and the next sheet, and from the sheeting nip part at the leading edge of the next sheet that has been stopped by the sheeting means. A protrusion amount detecting means for detecting the protrusion amount of the first member, a determining means for determining the deterioration state of the whirling member based on the protrusion amount detected by the protrusion amount detecting means, and a warning according to the deterioration state determined by the determining means Warning means that emits, and the protrusion amount detection means uses an area sensor to predetermine a predetermined range of the sheet surface including a position corresponding to the nip portion in the sheet conveyance direction. When it is determined that the position of the leading edge of the next sheet has moved based on the imaging means for imaging at the frame rate and the plurality of image data obtained by the imaging means, and it is determined that there is no movement And a calculating means for calculating the amount of protrusion of the leading edge of the next sheet from the nip portion at that time.

Here, the determination means determines that the rolling member has deteriorated when the amount of protrusion of the next sheet exceeds the first threshold, and the warning means warns that the rolling member should be replaced. It is characterized by.
Further, the counter further includes a counter for accumulating and counting the number of conveyed sheets, and the determination unit determines that the protrusion amount exceeds the first threshold before the count value by the counter reaches a predetermined value. Determines that the main cause of the rolling failure is paper dust adhering to the surface of the rolling member that contacts the paper feed roller, and the warning means warns that the paper dust on the peripheral surface of the rolling roller should be cleaned. It does not matter.

Here, the determination means determines that the replacement timing of the rolling member comes after feeding a predetermined number of sheets when the protrusion amount exceeds a second threshold value that is smaller than the first threshold value. The means may warn to that effect.
In addition, the protrusion amount detection unit includes an image pickup unit that picks up an image of a predetermined range of the sheet surface including a position corresponding to the separation nip portion in the sheet conveyance direction using an area sensor, and image data obtained by the image pickup unit. And a calculating means for detecting the position of the leading edge of the next sheet and calculating the amount of protrusion of the leading edge of the next sheet from the nip portion.

Here, the image pickup means continues the image pickup from the time when a predetermined time has elapsed from the start of the operation of the preceding sheet until at least the movement of the leading edge of the next sheet stopped.
Further, here, the imaging means is arranged so as to take an image of a range shifted in the main scanning direction by a predetermined distance from the rolling member in the rolling means, and the protrusion amount detecting means is controlled by the imaging means. Based on the obtained image data, an inclination amount with respect to the main scanning direction of the leading edge of the next sheet rolled by the rolling means is obtained, and based on the distance in the main scanning direction between the imaging means and the rolling member and the inclination amount The amount of protrusion of the next sheet from the winding nip portion at the axially central portion of the winding member is obtained.

  Further, based on the image data obtained by the imaging means, the leading edge of the preceding sheet separated from the succeeding sheet by the rolling means, or the preceding sheet surface between the leading edge of the preceding sheet and the leading edge of the next sheet A conveyance speed acquisition unit that detects a feature pattern of the image and acquires a conveyance speed of the preceding sheet; and a speed control unit that controls a rotation speed of the paper feed roller based on the acquired conveyance speed. It is desirable to provide.

  Further, each time the sheet is fed out from the sheet storage unit, the amount of protrusion of the next sheet fed from the rolling nip portion is statistically calculated, and a variation degree calculating unit that calculates the variation degree is provided. When the variation degree exceeds a predetermined threshold value, the amount of protrusion of the next sheet exceeds the first threshold value a plurality of times in succession, or a third threshold value that is larger than the first threshold value is set once. However, it may be determined that the rolling member is in a state to be replaced at the earlier point of time when it exceeds.

According to a fifth aspect of the present invention, there is provided a document reading device provided with the sheet transport device as a document transport device.
Furthermore, a sixth aspect of the present invention is an image reading apparatus including the sheet conveying device as a recording sheet conveying device.

  According to the above configuration, when the rollability of the rolling member is deteriorated, the next sheet fed is not rolled up in the rolled nip portion, and the leading end protrudes from the rolled nip portion. By detecting the amount, it is possible to accurately detect the state of deterioration of the rolling ability of the rolling member. Then, by issuing a warning that the rolling member should be replaced by the warning means, it is possible to prompt the replacement of the rolling member at an appropriate time.

1 is a schematic diagram showing an overall configuration of a copier according to a first embodiment of the present invention. FIG. 3 is a diagram illustrating each configuration and positional relationship between an operation unit of a paper feeding unit and an imaging unit in the copier according to the first embodiment. FIG. 3 is a schematic diagram illustrating a positional relationship between a separation portion and an imaging unit when FIG. 2 is viewed from a direction opposite to an arrow A. It is the schematic for demonstrating a mode that the sheet | seat of 2 sheets double fed by the nip part between the feeding roller of a separation part and a separation roller is rolled. It is a graph which shows the relationship between the fall of the friction coefficient (micro | micron | mu) 3 with respect to the recording sheet of the winding roller by deterioration of a winding roller, and the increase in the amount of protrusion of the next sheet. (A), (b) shows a photographed image by the imaging unit, (a) is a state where the leading edge of the next sheet does not protrude from the nip portion, and (b) is a leading edge of the next sheet. It is a figure which shows the state which has protruded from the rolling nip part, respectively. 2 is a block diagram showing a configuration of a control unit of the copying machine. FIG. It is a flowchart which shows the content of the roller roller deterioration state determination process in 1st Embodiment. FIG. 9 is a flowchart illustrating a subroutine of a next sheet protrusion amount detection process in step S14 of the flowchart of FIG. It is the schematic which shows the state which paper dust adhered to the surrounding surface of the whispering roller of a whispering part. It is a graph which shows that the value of friction coefficient (micro | micron | mu) 3 with a next sheet falls earlier than usual by paper dust adhering to a rolling roller. It is a flowchart which shows the content of the roller roller deterioration state determination process in the 2nd Embodiment of this invention. It is a figure which shows the positional relationship of an imaging position and a rolling roller when skew feeding has generate | occur | produced in the following sheet in a modification. It is a flowchart which shows the content of the next sheet protrusion amount detection process in case skewing has generate | occur | produced in the said next sheet. It is a figure for expanding and showing an example of a speckle pattern in a specific photographing position of a preceding sheet. 6 is a flowchart for detecting a conveyance speed of a preceding sheet by detecting a speckle pattern. It is a graph for demonstrating a mode that the judgment time of the deterioration state of a rolling roller is fluctuate | varied by the kind of sheet | seat and adhesion of paper dust. It is a flowchart which shows the content of the modification of the rolling roller deterioration state determination process in case there is variation in the amount of protrusion of the next sheet.

Hereinafter, a sheet conveying apparatus according to an embodiment of the present invention will be described by taking as an example a case where the sheet conveying apparatus is applied to a sheet feeding unit in a copying machine.
<First Embodiment>
FIG. 1 is a schematic diagram for explaining the configuration of a copying machine 1 according to the present embodiment.
As shown in FIG. 1, the copying machine 1 is roughly divided into an image reader unit (original reading device) A and a printer unit (image forming device) B.

The image reader unit A includes a scanner unit 10 that optically reads a document image and converts it into an image signal, and a document transport unit (ADF unit) 11 provided above the scanner unit 10. The apparatus is configured to selectively execute reading of a document image by both the through method and the mirror scan method.
The printer unit B forms a color image on a recording sheet based on the original image read by the image reader unit A and image data transmitted from another terminal via the network by electrophotography. Is.

The configuration of each part will be described below.
(1) Image reader unit (1-1) Document transport unit The document transport unit 11 feeds a document from a bundle of documents set on the document feed tray 111 by a pick-up roller 113 when a sheet-through reading is performed, and rolls the document. The document 114 is separated one by one by the section 114, skew correction is performed by the registration roller pair 115 and the timing is set, and the document is fed toward the reading position on the first reading glass 101, and the document image is read at the reading position. After that, the document is discharged to the document discharge tray 117 through the discharge roller pair 116.

The lift plate 112 provided on the document feed tray 111 is swung upward by a cam mechanism (not shown) when the pickup roller 113 is fed, and the upper surface of the uppermost document in the document bundle is placed on the pickup roller 113. It is for making it contact | abut.
(1-2) Scanner Unit On the upper surface of the housing 100 of the scanner unit 10, a strip-shaped first reading platen glass 101 and a flat plate-like second reading glass 102 are provided.

Inside the housing 100, a first slider 103 and a second slider 104, a condenser lens 105, a line sensor 106, and the like are disposed.
The line sensor 106 includes a plurality of CCDs (Charge Coupled Devices) arranged linearly on a substrate.
A linear light source 103a and a first mirror 103b are mounted on the first slider 103, and are slid in the direction of arrow C by a drive motor (not shown).

A pair of mirrors 104a and 104b is installed on the second slider 104 at an angle of 90 degrees, and moves in the same C direction at half the speed of the first slider 103 by wire driving using a moving pulley. It is configured as follows.
As the linear light source 103a, a light source such as a fluorescent lamp, a xenon lamp, or an LED is usually used.

When reading an image of an original placed manually on the second reading glass 102 (mirror scan method), the first slider 103 slides in the direction of arrow C while the second reading light is read from the linear light source 103a. Light is emitted toward the document placed on the glass 102.
The second slider 104 provided with the second mirror 104a and the third mirror 104b is configured to slide in the C direction at half the moving speed of the first slider 103. The optical distance up to 105 can be kept constant. As a result, the image of the document placed on the second reading glass 102 is imaged by the line sensor 106 via the condenser lens 105.

On the other hand, when reading an image of a document conveyed on the first reading glass 101 by the document conveying unit 11 (sheet through method), the first slider 103 has a linear light source 103a as shown in FIG. It is maintained at a position where light can be irradiated from directly below the first reading glass 101 toward the document.
The line sensor 106 converts the incident reflected light from the document into an electrical signal and outputs it to the control unit 50.

(2) Printer Unit The printer unit B includes an image forming unit 20, a paper feeding unit 30, a fixing unit 40, a control unit 50, and the like. The image forming section 20 is arranged along an intermediate transfer belt 22 that is driven to rotate in the direction of arrow D by a drive source (not shown), and a portion that moves horizontally on the lower side of the intermediate transfer belt 22. Process units 23Y, 23M, 23C, and 23K.

The process units 23Y, 23M, 23C, and 23K form toner images of each color of yellow (Y), magenta (M), cyan (C), and black (K), respectively.
Since these process units 23Y to 23K have the same configuration except for the color of the toner to be filled, only the configuration of the process unit 23K will be described as a representative.

The process unit 23K has a charging unit 25K, an exposure unit 26K, and a developing unit 27K around the photosensitive drum 24K.
The outer circumferential surface of the photosensitive drum 24K is uniformly charged by the charger 25K.
The exposure device 26K modulates and drives the laser light source based on the image data acquired by the image reader unit A, and exposes and scans the surface of the charged photosensitive drum 24K. Thereby, an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 24K.

The electrostatic latent image is developed with black toner by the developing device 27K.
Further, a primary transfer roller 28K is provided above the photosensitive drum 24K at a position sandwiching the intermediate transfer belt 22.
The primary transfer roller 28K forms an electric field with the photosensitive drum 24K. As a result, the toner image on the photosensitive drum 24K is transferred onto the intermediate transfer belt 22 by the action of the electric field.

  Similarly, primary transfer rollers 28Y, 28M, and 28C are respectively provided above the other process units 23Y, 23M, and 23C with the intermediate transfer belt 22 interposed therebetween, and the photoconductors in the process units 23Y, 23M, and 23C are provided. The Y, M, and C color toner images formed on the drum are transferred onto the intermediate transfer belt 22. A color image is formed by superimposing and transferring toner images of each color of Y, M, C, and K at the same position on the intermediate transfer belt 22.

The toner image transferred onto the intermediate transfer belt 22 is conveyed to a secondary transfer position 21 a facing the secondary transfer roller 21 by a rotating operation of the intermediate transfer belt 22.
On the other hand, the paper feeding unit 30 feeds the recording sheets S stored in the paper feeding cassette 31 and conveys them one by one to the secondary transfer position 21a.
The bundle of recording sheets S is placed on a lifting plate 32 disposed in a sheet feeding cassette 31 so as to be lifted and lowered by a lift mechanism (not shown), and the lifting plate 32 is swung upward to form a sheet. The surface of the uppermost recording sheet S in the bundle is configured to abut on the peripheral surface of the pickup roller 33.

  The recording sheet S fed out by the rotation of the pickup roller 33 passes through a nip portion (hereinafter, referred to as a “rolling nip portion”) of a rolling portion 34 including a paper feed roller 35 and a rolling roller 36. Is supplied with a predetermined load torque that acts in the direction opposite to the conveying direction by a torque limiter (not shown). If the pickup roller 33 causes double feeding of the recording sheet S, the rolling nip portion In one, it is beaten.

  The recording sheet S that has been rolled in the rolling nip portion is conveyed in the vertical direction to the registration roller pair 38 on the downstream side in the sheet conveying direction via the vertical conveying roller pair 37 (hereinafter referred to as recording sheet conveyance in this specification). The downstream side and the upstream side in the direction are simply referred to as “downstream side” and “upstream side.” For convenience, the portion from the pickup roller 33 to the paper feed roller 35 in the transport path of the paper feed unit 30 is “paid out”. Section ”, the vertical conveyance section from the vertical conveyance roller pair 37 to the discharge roller pair 39 is referred to as“ vertical conveyance section ”).

Reference numeral 320 in front of the vertical conveyance roller pair 37 indicates a jam detection sensor. If the trailing edge of the recording sheet S cannot be detected even after a predetermined time has elapsed after the jam detecting sensor 320 detects the leading edge of the recording sheet S, it is determined that a jam (paper jam) has occurred. It has become.
Further, reference numeral 201 in the vertical transport unit is a vertical transport sensor, and reference numeral 202 is a timing sensor.

Each of the jam detection sensor 320, the vertical conveyance sensor 201, and the timing sensor 202 includes, for example, a well-known reflection photoelectric sensor including a light emitting element and a light receiving element that detects reflected light from the recording sheet S of light emitted from the light emitting element. It consists of sensors and is used to detect the leading edge or trailing edge of the recording sheet S at each detection position.
For example, when the detection signal of the vertical conveyance sensor 201 rises from OFF to ON, the control unit 50 determines that the leading edge of the recording sheet S has passed the detection position of the vertical conveyance sensor 201 and falls from ON to OFF. It is determined that the trailing edge of the recording sheet S has passed the detection position of the vertical conveyance sensor 201.

When the leading edge of the recording sheet S is detected by the vertical conveyance sensor 201 arranged immediately downstream of the vertical conveyance roller pair 37, the driving of the pickup roller 33 and the paper feed roller 35 in the feeding unit is stopped.
Each of the pickup roller 33 and the paper feed roller 35 is rotationally driven by a paper feed motor via a one-way clutch (not shown). The one-way clutch is a well-known one that transmits power only in one rotational direction. In this embodiment, each sheet feeding motor is moved in a predetermined direction to convey the recording sheet to the downstream side (secondary transfer roller 21 side). , The rotational force is transmitted to the rotating shaft of the corresponding roller. However, when the driving is stopped, the rotating force is idled so that the conveyance of the recording sheet S by the longitudinal conveying roller pair 37 is prevented. ing.

  The registration roller pair 38 initially stops rotating, and after the leading edge of the recording sheet S is detected by the timing sensor 202, the recording sheet S is continuously conveyed by the vertical conveyance roller pair 37 for a predetermined time, thereby causing the vertical conveyance. A loop is formed between the roller pair 37 and the registration roller pair 38, and the leading edge of the recording sheet S is in a state along the nip portion of the registration roller pair 38 due to the stiffness of the recording sheet S.

Thereafter, the registration roller pair 38 is rotated at a predetermined timing to send out the recording sheet S, so that the skew (skew) of the recording sheet S is corrected and conveyed to the downstream secondary transfer position 21a. A color toner image is transferred onto the recording sheet S.
If the trailing edge of the recording sheet S cannot be detected after a predetermined time has elapsed after the jam detection sensor 320 detects the leading edge of the recording sheet S, the control unit 50 detects a jam (paper jam) at this portion. ) Has occurred, the operation of the entire copying machine 1 is stopped, and a jam occurrence message is displayed on the operation panel 60 (not shown in FIG. 1, see FIG. 7).

Further, in order to monitor the whirling state at the whirling section 34, an imaging unit 300 that captures the leading edge of the lower sheet (next sheet) of the double fed sheet is below the whirling section 34 and is fed. It is arranged at a position (see FIG. 3) slightly shifted in the rotation axis direction from the position of the paper roller 35. Details will be described later.
The recording sheet on which the toner image is transferred at the secondary transfer position 21a is heated and pressurized by the fixing device 40 above the secondary transfer position 21a, and the toner image transferred to the recording sheet is fixed on the recording sheet. The

The recording sheet on which the toner image is fixed is discharged onto a discharge tray 391 via a discharge roller pair 39.
The toner that has not been transferred onto the recording sheet on the intermediate transfer belt 22 is removed by the cleaning blade 29.
In the above, the operation in the case of executing the color mode has been described. However, in the case of executing monochrome (for example, black) printing (monochrome mode), only the black image forming unit 23K is driven, and the same as described above. With this operation, black image formation is performed on the recording sheet through the steps of charging, exposing, developing, transferring, and fixing the black color.

  An operation panel 60 (see FIG. 7) is disposed at a position on the front side and the upper side of the apparatus main body and easy to be operated by the user. The operation panel 60 includes a hard key 61 that receives various instructions from the user, a display unit 62 that includes a touch panel type liquid crystal display board, and the like, and transmits the instruction content received from the user to the control unit 50 or a copying machine. Information indicating the state of 1 can be displayed on the display unit 62.

The control unit 50 controls the document conveying unit 11 in the image reader unit A, the scanner unit 10, the image forming unit 20 in the printer unit B, the paper feeding unit 30, the fixing unit 40, and the like to execute a smooth copy operation and print operation. Let
Further, the control unit 50 obtains the amount of protrusion of the leading edge of the next sheet from the separation nip portion based on the imaging data of the imaging unit 300, and thereby determines the deterioration state of the separation roller 36.

(3) Imaging unit 300
(3-1) Configuration of the Imaging Unit 300 FIG. 2 shows the configuration of the imaging unit 300 for obtaining the amount of protrusion of the leading edge of the next sheet that has been double-fed by the feeding unit of the sheet feeding unit 30 from the separation nip. FIG.
As shown in the figure, an imaging unit 300 has an area sensor 301 and a light emitting element 302 mounted on the same substrate 303 as imaging elements, and diffuses light emitted from the light emitting element 302 to irradiate a predetermined imaging range. A lens 305 and a lens 304 for forming an image of the imaging range on the light receiving surface of the area sensor 301 are provided, and these are housed in a casing 306.

3 shows the main scanning direction (horizontal in FIG. 3) of the sheet feeding roller 35, the separation roller 36 and the imaging unit 300 of the separation unit 34 when viewed from the right direction in FIG. 2 (the direction opposite to the sheet discharge direction A). It is a figure which shows the positional relationship in (direction) roughly.
As shown in FIG. 3, the paper feed roller 35 and the paper feed roller 36 of the paper separation unit 34 are arranged in the center in the width direction of the recording sheet S stored in the paper supply cassette 31.

  In the figure, for the sake of simplification, only the paper feed roller 35 of the separating unit 34 and the roller main unit of the separating roller 36 are shown, but in actuality, each roller can rotate to a frame (not shown) via its rotation axis. The frame of the whirling roller 36 is urged in the direction of the paper feed roller 35 by an urging means (not shown). As a result, a nip N is formed between the paper feed roller 35 and the nip 34.

The imaging unit 300 is at a position shifted in the axial direction (main scanning direction) from the separation unit 34 so as not to overlap with the separation roller 36 of the separation unit 34 and the minimum width that can be used in the copying machine 1. Recording sheets (for example, A5 size vertical) are arranged at positions where they can be imaged.
Then, the lenses 304 and 305 and the area sensor are set so that the imaging range by the imaging unit 300 is a predetermined rectangular range D (see FIGS. 6A and 6B) across the extension line of the rolling nip portion N. 301 and the relative positional relationship of the light emitting element 302 are determined.

In the present embodiment, the light emitting element 302 is preferably a light emitting diode (LED) or an organic LED, which has the advantage of low power consumption and long life, but of course not limited to this, the laser diode (LD), In some cases, a small incandescent bulb may be used.
Further, although the area sensor 301 uses a two-dimensional CCD in this embodiment, the area sensor 301 is not limited to this and may be a two-dimensional CMOS.

(3-2) Method for Determining Degradation State of Rolling Roller FIG. 4 is a schematic diagram showing a state in which the recording sheets S1 and S2 that have been multi-fed are rolled by the rolling unit.
In addition, the most downstream position in FIG. 4 is previously determined for each model by experiment as a position where normal continuous conveyance becomes difficult while maintaining the prescribed gap when the leading edge of the next sheet exceeds the position. In this embodiment, the recording sheet conveyance speed is set to about 6.4 mm in a model in which the recording sheet conveyance speed is 165 cm / s and the designed inter-paper distance is 60 mm.

As shown in the drawing, the coefficient of static friction between the peripheral surface of the paper feed roller 35 and the surface of the recording sheet S1 (hereinafter simply referred to as “friction coefficient”) is μ1, and between the recording sheets S1 and S2. And the friction coefficient between the peripheral surface of the roller 36 and the surface of the recording sheet S2 is μ3.
When the separation nip width is wn, the nip pressure is highest at the center position of the nip width in the sheet conveyance direction (hereinafter referred to as “nip center”), and both ends of the separation nip N (inlet side and outlet side). ) The smaller it goes. Since it is understood that the nip pressure is applied in a direction substantially perpendicular to the paper surface of the recording sheet to be passed, it can be regarded as normal drag, and the total nip pressure in the entire nip width is Pn. A certain preceding sheet S1 has a frictional force f1 = μ1 × Pn applied from the paper feed roller 35 in the transport direction.

Further, since the mass of the sheet itself is very small, it is understood that the frictional force between the recording sheets generated in the portion other than the rolling nip portion N can be almost ignored. Therefore, between the preceding sheet S1 and the next sheet S2. The applied frictional force f2 = μ2 × Pn may be considered.
The next sheet S2 can be expressed as a frictional force f3 = μ3 × Pn received in the direction opposite to the sheet conveying direction A by the rolling roller 36.

  In order to reliably feed the preceding sheet S1, the friction coefficient μ1 is normally set to be the largest. Then, when f3 ≧ f2, the sheet S2 is separated from the sheet S1 and is rolled, so in the end whether or not the sheet S2 is rolled by the rolling roller 36 depends on the friction coefficient μ2 between the sheets and the sheet and the rolling roller. 36 and the friction coefficient μ3.

  FIG. 5 shows the change over time of the friction coefficient μ3 with respect to the number of sheets fed by the winding unit 34 and the amount of protrusion from the winding nip N at the leading end of the sheet S2 (the next sheet S2 that has been fed is rolled by the winding unit 34. Distance dx (see FIG. 6B) from the exit-side end of the separation nip portion N to the position of the leading end of the sheet S2 when the movement is stopped: hereinafter, “next sheet protrusion amount” or simply “projection amount” It is a graph showing the change of “.

  Since the roller roller 36 is usually made of an elastic material such as silicone rubber, the friction coefficient μ3> μ2 in the new state, and there is no problem with the roller roller 36 in the initial stage. When the peripheral surface of the roller 36 is worn with time (the number of recording sheets fed) and the friction coefficient μ3 becomes smaller than μ2, slip occurs between the sheet S2 and it is difficult to roll the sheet 2. Become.

That is, since new sheets are sequentially fed from the sheet feeding cassette 31 and the same kind of sheets are usually stored in the sheet feeding cassette 31, the friction coefficient μ2 is slightly increased due to moisture absorption or the like. If variation is ignored, it can be considered to be almost constant (see the broken line L2 in FIG. 5).
However, as the number of sheets fed increases, the surface of the roller 36 is worn and the friction coefficient μ3 with the sheet gradually decreases (see the solid line L1). In the graph, for the sake of simplification, the friction coefficient μ3 is shown to linearly decrease according to the number of sheets fed.

  Thus, the friction coefficient μ3 decreases due to wear of the rolling roller 36, and when the friction coefficient μ2 between the sheets becomes equal when the number of fed sheets is n1, slip starts to occur between the sheet S2 and the rolling roller 36. (The position of the number n1 of sheets fed), the sheet S2 is not sufficiently wound by the sheet roller 36, and the leading edge of the sheet S2 gradually protrudes downstream from the sheet nip portion N.

  Since the next sheet S2 always receives a force in the direction opposite to the conveying direction from the rolling roller 36, if the difference between the friction coefficients μ2 and μ3 is small, the next sheet S2 is also stopped. A curve L3 indicated by a broken line in FIG. 5 shows a change in the protruding amount of the next sheet S2 at the stop position, and the protruding amount of the sheet S2 gradually increases as the number of fed sheets increases after the slip occurs, and the most downstream. It can be seen that there is a sharp increase from near the position.

In the graph, when the number of fed sheets is n2, the protruding amount of the next sheet S2 reaches the above-mentioned most downstream position, and this time is regarded as the replacement time.
That is, whenever the recording sheet is sequentially fed out and conveyed, the protrusion amount at the stop position of the next sheet S2 is monitored, and the position is the most downstream position (the conveyance path from the end on the exit side of the nip portion N to the most downstream position). It is possible to determine that the effective time of the roller 36 has arrived when the upper limit value dmax is reached.

6A and 6B show captured images of the preceding sheet S1 and the next sheet S2 obtained by the imaging unit 300. FIG.
FIG. 6A shows a state where the leading edge E of the next sheet S2 is stopped in a state where the leading edge E does not protrude from the nip portion, and FIG. 6B shows that the leading edge E of the next sheet S2 is rolled. A state in which only dx protrudes from the nip portion and stops is shown. In both figures, Es is a shadow of the leading edge E of the next sheet S2 on the surface of the preceding sheet S1. By analyzing the image data, the position of the leading edge E can be detected, and the amount of protrusion can be easily obtained.

Thus, based on the imaging data in the imaging unit 300, the sheet feeding roller 36 is monitored by monitoring the amount of protrusion of the leading edge of the next sheet lower than the uppermost preceding sheet to be conveyed at the time of feeding each time. It is possible to grasp the replacement time.
(4) Configuration of Control Unit 50 FIG. 7 is a block diagram showing a main configuration of the control unit 50.

As shown in the figure, the control unit 50 includes a CPU (Central Processing Unit) 51, a communication I / F (interface) 52, a RAM (Random Access Memory) 53, a ROM (Read Only Memory) 54, and an EEPROM (registered trademark). ) And the like.
When the power to the copying machine 1 is turned on, the CPU 51 reads a target control program from the ROM 54 and executes the control program using the RAM 53 as a working storage area.

In addition, the CPU 51 receives a print job from another terminal via a communication network such as a LAN by the communication I / F 52.
The non-volatile memory 55 mainly stores a cumulative value of the number of prints for maintenance and other histories.
The CPU 51 controls the document transport unit 11 and the scanner unit 10 in the image reader unit A to read a document image and generate image data. The CPU 51 also reads the read image data or an external device via the communication I / F 52. Based on the print job data received from the terminal device, the image forming unit 20, the paper feeding unit 30, the fixing unit 40 and the like in the printer unit B are controlled to smoothly execute the copy operation and the print operation.

  Further, the CPU 51 turns on the light emitting element 302 and drives the area sensor 301 of the imaging unit 300 via the area sensor driving unit 310 at the time of paper feeding, acquires image data from the area sensor 301, and the image data Is detected to detect the position of the leading edge of the next sheet S2, thereby performing a process for determining the deterioration state of the roller 36 (a roller roller deterioration state determination process), which is necessary for the display unit 61 of the operation panel 60. Display a message to warn the user.

(5) Content of Rolling Roller Deterioration State Determination Process FIG. 8 is a flowchart showing the content of the above-described rolling roller deterioration state determination process that is executed by the feeding unit during sheet conveyance.
First, it is determined whether it is time to send out the recording sheet and start feeding (step S11). This timing is determined in association with the progress state of the image forming operation in the image forming unit 20.

If it is the timing to start feeding (YES in step S11), driving of the feeding unit (pickup roller 33, paper feeding roller 35) in the paper feeding unit 30 is started, and the preceding sheet S1 is fed out (step S12). The number of sheets to be sent is counted up (step S13).
Next, a next sheet protrusion amount detection process for detecting a protrusion amount from the leading nip portion of the leading edge of the fed next sheet S2 is executed (step S14).

FIG. 9 is a flowchart showing the contents of a subroutine of the next sheet protrusion amount detection process.
The CPU 51 acquires imaging data at a constant frame rate from the area sensor 301 of the imaging unit 300 (see FIGS. 6A and 6B) (step S101).
The imaging unit 300 does not always have to image the recording sheet during the sheet conveying operation, but the necessary information is the protrusion amount (stop position) of the next sheet fed, so at least the preceding sheet by the pickup roller 33 After the elapse of a predetermined time (for example, the time until the preceding sheet stored in the paper feed cassette 31 arrives at the separation unit 34) from the start of feeding until it is determined that the movement of the leading edge of the next sheet has stopped. It is desirable that imaging be continued.

Then, edge enhancement processing is performed on the imaged data (step S102), and the leading edge of the next sheet S2 is detected (step S103).
The edge enhancement processing here uses a known method using an edge enhancement filter or the like.
However, as described above, the shadow Es of the leading edge of the next sheet S2 is reflected on the surface of the preceding sheet S1 by the amount corresponding to the thickness of the next sheet S2 (see FIGS. 6A and 6B). (Refer to the shadow E1) Since the brightness difference appears relatively clearly in this portion, the edge emphasis process is not necessarily required.

  Then, for example, in the image data of the photographed image of FIG. 6B, the difference in density of pixels adjacent from the left to the right (x direction: sheet conveyance direction) is sequentially obtained, and the density difference is a predetermined constant. When a pixel exceeding the threshold value is determined as a leading edge, this edge detection operation is repeated while moving in the x direction, whereby all the leading edge E pixels are detected, and the line connecting the pixels is an edge. Specified as part.

However, in order to specify the position of the leading edge of the next sheet S2, it is not necessary to continuously obtain the position of the leading edge E for all of the sheet width direction, and if the leading edge E is detected at an appropriate interval. Good.
Needless to say, the edge detection method is not limited to the above, and other known techniques may be used.

  Then, it is determined whether or not the current leading edge E has moved from the position of the leading edge E in the previous frame image (step S104), and if it has moved, the possibility of further movement is high. Image data at the next frame rate is acquired (NO in step S104, step S101), and the processing in steps S102 to S104 is repeated. When it is determined in step S104 that the leading edge is no longer moved (step S104). YES), the next sheet protrusion amount dx from the nip portion of the leading edge at that time is obtained (step S105), and the process returns to the flowchart of FIG.

The address on the memory at the position corresponding to the outlet of the nip portion is obtained in advance and stored in, for example, the nonvolatile memory 55, and the control unit 50 detects the address on the outlet side of the nip portion and the above-described detection. Based on the address information of the edge pixel, the next sheet protrusion amount dx can be obtained from the difference.
In step S15 of FIG. 8, based on the acquired next sheet protrusion amount dx, it is first determined whether or not the leading edge of the next sheet S2 has exceeded the nip portion (ie, dx ≦ 0: step). NO in S15), since there is no problem in the separating ability of the separating roller 36, it is determined whether or not the next sheet needs to be fed in the next step S19. If the next sheet needs to be fed, the process returns to step S11. , Steps S12 to 19 are repeated.

If it is determined in step S15 that the leading edge of the next sheet has passed the nip (dx> 0: YES in step S15), the next sheet protrusion amount dx has reached the upper limit value dmax in step S16. It is determined whether or not.
If the next sheet protrusion amount dx is less than the upper limit value dmax (NO in step S16), a message indicating that it is time to replace the roller 36 (in this embodiment, for example, a predetermined number of sheets (for example, 1000 sheets) When it is expected that the replacement time will come if it is fed, it is assumed that “the replacement time is approaching.”) Is displayed on the display unit 62 of the operation panel 60 and the user is notified in advance. A warning is given (step S17). In this way, it is possible to replace parts of the roller 36 and arrange for maintenance earlier than when a warning is given that it is suddenly time to replace, and a user-friendly device can be obtained.

If the next sheet protrusion amount dx has reached the upper limit value dmax (YES in step S16), a message to the effect that the roller 36 should be replaced is displayed on the display unit 62 of the operation panel 60 to warn the user. (Step S18).
If it is not necessary to feed the next sheet (NO in step S19), the rolling roller deterioration state determination process is terminated.

As described above, according to the sheet conveying apparatus according to the present embodiment, every time a sheet is fed, the position of the leading edge of the next sheet that has been fed is checked and the nip portion of the leading edge is separated. By determining the amount of protrusion from the roller, it is possible to reliably determine the deterioration state of the roller 36.
As a result, it is possible to replace the roller at an appropriate time before troubles such as paper jam frequently occur, and the quality of the maintenance service by the service person is improved.

<Second Embodiment>
Next, the configuration of the copier according to the second embodiment will be described.
The copying machine according to the second embodiment has the same hardware as the first embodiment, and only the contents of the roller deterioration state determination process are different. explain.

  Depending on the recording sheet, paper dust generated at the time of manufacture may adhere to the surface, or paper dust may be newly generated due to friction with the rolling roller 36. Such paper dust 361 (shown exaggerated in FIG. 10) is easily attached to the peripheral surface of the roller 36 positioned below the recording sheet being conveyed due to the influence of gravity. As the paper dust 361 adheres to the peripheral surface of the rolling roller 36, the friction coefficient with the recording sheet gradually decreases.

That is, the paper dust 361 adheres to the peripheral surface of the whirling roller 36 in the whirling portion 34, although the whirling ability of the whirling roller 36 itself is not deteriorated so much as in the first embodiment. Then, there is a risk that the rolling ability deteriorates earlier than feeding the scheduled number of sheets to be fed.
FIG. 11 is a graph showing changes in the friction coefficient of the rolling roller 36 and changes in the amount of protrusion of the next sheet from the rolling nip portion in such a case.

  A solid straight line L11 indicates a change with time of the friction coefficient μ3 between the rolling roller 36 and the sheet S2 when the paper dust 361 is not attached to the rolling roller 36, and a broken line L21 in this case The broken line L12 indicating the sheet protrusion amount curve is a time-dependent change in the friction coefficient μ3 between the sheet roller 361 and the sheet S2 with respect to the number of sheets fed when the paper dust 361 adheres to the sheet roller 36. A change is shown, and a broken line L22 shows a sheet protrusion amount curve in this case.

As is apparent from the graph, when the paper dust 361 adheres to the rolling roller 36, the friction coefficient μ3 is also reduced rapidly, and slip occurs between the next sheet S2 at an early point.
In the present embodiment, in the rolling roller deterioration state determination process, it is determined whether the rolling failure due to the rolling roller 36 is caused only by wear of the rolling roller 36 or the adhesion of the paper dust 361 is also affected. It is characterized in that the contents of the warning can be changed, and the hardware is exactly the same as in the first embodiment.

FIG. 12 is a flowchart showing the contents of the roller-roller deterioration state determination process in the present embodiment. Steps showing the same processes as those in FIG. 8 are given the same step numbers.
The processing in steps S11 to S17 is exactly the same as in FIG. 8, but if it is determined in step S16 that the next sheet protrusion amount has exceeded the upper limit (YES in step S16), the number of sheets fed at that time It is determined whether or not the count value is smaller than the reference number (step S201).

  Here, the reference number of sheets refers to a predetermined safety factor (a predetermined safety factor) obtained by repeating experiments in advance when the paper roller 361 is not attached and the number of sheets fed when the roller 36 arrives at the replacement time. For example, the value is set by multiplying 0.9), and is set to about 250,000 sheets, for example. This safety factor is determined empirically from the viewpoint that it is possible to determine that the replacement time of the roller 36 has not been reached even when used in a paper type variation or in a bad use environment (for example, high temperature and high humidity). .

In step S201, when it is determined that the count value of the number of sheets to be fed is smaller than the reference number (YES in step S201), it is considered that the paper powder 361 has caused a scraping defect. A warning for prompting cleaning of the roller is displayed on the display unit 62 of the operation panel 60 (step S202).
On the other hand, if it is determined that the count value of the number of sheets to be fed is equal to or more than the reference number (NO in step S201), it is assumed that a rolling defect has occurred due to deterioration of the roller 36 itself. Judgment is made and a warning that the roller should be replaced is displayed on the display unit 62 (step S18).

Thereafter, it is determined whether or not it is necessary to feed the next sheet. If necessary, steps S11 to S19 are repeated. If not necessary, the roller-roller deterioration state determination process is terminated.
Based on the warnings in steps S17, S18, and S202, the user responds by itself or contacts a maintenance company service person to request the necessary maintenance.

It should be noted that the cumulative count value of the number of sheets to be fed is configured such that when the roller 36 is replaced with a new one, a service person, for example, inputs a password from the operation panel 60 and logs in to reset. desirable.
<Modification>
As described above, the present invention has been described based on the embodiment. However, the present invention is not limited to the above-described embodiment, and the following modifications may be considered.

(1) In order to detect the protrusion amount of the leading edge of the next sheet from the separation nip portion, in the above embodiment, the area sensor is used to analyze the imaging screen to detect the leading edge of the next sheet. The edge position of the next sheet can be detected even if the line sensor is arranged so that the arrangement direction of the array is parallel to the sheet conveyance direction.
However, the area sensor has the merit that the leading edge of the next sheet can be reliably detected by image processing (edge enhancement processing) using a spatial filter, and the function described below can be realized. it can.

(1-1) Skew Detection FIG. 13 is a schematic diagram showing the positional relationship between the sheets S1 and S2 within the imaging range of the imaging unit 300 and the rolling roller 36 when the vicinity of the winding unit 34 is viewed from below the apparatus. It is.
By analyzing the imaging data, the values of the protrusion amounts d1 and d2 at two different points P1 and P2 on the edge E of the next sheet S2 (the uppermost end and the lowermost end in the imaging range D for convenience in FIG. 13) are obtained. If d1 = d2, the next sheet S2 is not skewed. If d1 = d2, it can be determined that the difference is skewed.

In FIG. 13, an edge portion E is displayed in a state where the next sheet S2 is inclined by θ in the left rotation direction and d1 <d2.
Usually, the center position in the axial direction of the separating roller 36 is arranged so as to be on the sheet passing width center Lc which is the center position of the sheet passing width. Therefore, the effective protrusion amount for determining the deterioration degree of the separating roller 36 is as follows. It is considered that the amount of protrusion d3 on the sheet passing width center Lc is small in the influence of the rotational force acting on the sheet S2.

This protrusion amount d3 is obtained by calculation by analyzing the captured image, assuming that the main scanning direction of the points P1 and P2 is the distance g1, and the length of the perpendicular line from the point P1 of the imaging range D to the sheet passing center Lc is g2. It can be easily obtained from the obtained values of d1 and d2.
tan θ = d4 / g1
= (D2-d1) / g1
Therefore, d3 = d1 + g2 · tan θ
= D1 + g2 · (d2-d1) / g1
Since g1 and g2 are known values determined at the design stage, by obtaining d1 and d2, the next sheet protrusion amount d3 for determining the deterioration state of the rolling roller 36 can be easily obtained.

FIG. 14 is a flowchart showing the contents of a subroutine for the next sheet protrusion amount detection process when skew occurs in the next sheet S2.
The CPU 51 acquires imaging data for one frame from the area sensor 301 at a constant frame rate (step S301), performs edge enhancement processing on the imaging data (step S302), and detects the leading edge of the next sheet S2. (Step S303).

  Then, it is determined whether or not the current leading edge has moved from the position of the leading edge in the previous frame image (step S304), and if it has moved, the possibility of further movement is high. Image data at the frame rate is acquired (NO in step S304, step S301), and thereafter, the processes in steps S302 to 304 are repeated. If it is determined in step S304 that the leading edge is no longer moved (YES in step S304). Then, the protrusion amounts d1 and d2 from the winding nip portion at two points on the leading edge E2 at that time are obtained, and the presence or absence of the skew of the next sheet S2 is determined (step S305).

If it is determined that the next sheet S2 is skewed (YES in step S305), the rolling nip portion of the edge portion of the next sheet S2 on the sheet passing center Lc from the inclination angle of the leading edge portion of the next sheet S2. The distance d3 from the sheet is obtained, and this is set as the next sheet protrusion amount (step S306).
If it is determined in step S305 that no skew has occurred in the next sheet S2, the distance d1 (or d2) from the leading nip portion of the leading edge of the next sheet S2 is set as the next sheet protrusion amount. (Step S307).

Then, the process returns to the flowchart of FIG. 8. By using the area sensor in this way, even if the next sheet S2 is skewed, this is easily detected, and the amount of protrusion of the next sheet at the necessary part is obtained and rolled. The degree of deterioration of the roller 36 can be determined.
(1-2) Conveyance Speed Detection Further, by using the area sensor 301, the conveyance speed of the preceding sheet S1 can also be detected.

In general, when a rough surface such as paper or a wall is irradiated with coherent light such as laser light and the reflected light is magnified and observed, the scattered light interferes with each other, and a broken-line circle F in FIG. It is known that a bright and dark spot pattern can be seen as shown in the enlarged view of FIG. Such a spotted pattern is called a speckle pattern and forms a characteristic pattern for each rough surface shape.
Therefore, a laser diode is used as the light emitting element 302, and an image of a specific part of the surface of the preceding sheet S1 is analyzed along with detection of the leading edge of the next sheet S2, and the speckle pattern characteristic in the part is analyzed. By extracting a simple shape (for example, an arrangement state of high luminance points) and detecting the movement amount of the speckle pattern for each frame rate, the conveyance speed of the preceding sheet S1 can be accurately obtained.

FIG. 16 is a flowchart showing the content of the conveyance speed detection process by the paper feed roller 35 of the preceding sheet S1 based on the detection of the speckle pattern.
First, image data photographed by the imaging unit 300 is acquired (step S401), and the image data on the surface of the preceding sheet S1 is analyzed from the image data to extract the shape of the speckle pattern at a specific location ( Step S402).

The same speckle pattern as described above is detected from the image data of the next frame (step S402), and the transport speed of the preceding sheet S1 is obtained by calculating the movement amount of the characteristic portion (step S404). .
Since the time interval (frame rate) of imaging by the imaging unit 300 is determined by design, the conveyance speed can be easily acquired by dividing the movement amount of the speckle pattern by the frame rate.

The technique itself for detecting the moving speed of the object surface by detecting the speckle pattern is disclosed in detail in, for example, Japanese Patent Application Laid-Open No. 2014-178294 and Japanese Patent Application Laid-Open No. 2010-55064. do not do.
Then, it is determined whether or not the measurement of the conveyance speed is finished (step S405). If it is not the timing at which the measurement should be finished yet (NO in step S405), the timing to repeat the steps S402 to S404 and finish the measurement. If YES (YES in step S405), the conveyance speed detection process ends.

In this modification, the speed measurement based on the detection of the speckle pattern is mainly performed to control the conveyance speed of the preceding sheet S1 passing through the winding nip portion. For example, it can be set as the timing at which the trailing edge of the preceding sheet S1 passes the nip portion.
The conveyance speed of the preceding sheet S1 thus detected is fed back to the control unit 50, and the control unit 50 determines the rotation speed of the drive source of the paper feed roller 35 (if necessary, rotation of the vertical conveyance roller 37). The speed is also controlled so that the leading edge of the preceding sheet S1 reaches the nip of the registration roller pair 38 by a predetermined time.

  By detecting the speed of the preceding sheet S1 by the above-described method, the following advantages can be obtained. That is, the preceding sheet S1 that is passing through the rolling nip portion receives torque in the opposite direction via the next sheet S2, and the rotational speed of the paper feed roller 35 may fluctuate slightly. It is difficult to control the conveyance speed to the target value. In the method of controlling the conveyance speed by detecting the rotation speed of the paper feed roller 35, the paper feed roller 35 may be worn and slipped, and the conveyance speed of the preceding sheet S1 may not be accurately detected. The actual conveyance speed is accurately detected from the sheet surface at the leading edge of the preceding sheet S1 being conveyed, and the rotation speed of the paper feed roller 35 (including the vertical conveyance roller 37 in some cases) is controlled. The leading edge of the preceding sheet S1 is brought into contact with the nip portion of the stopped registration roller pair 38 by the timing of the above to form a loop of an amount necessary for skew correction, and then the registration roller pair 38 is driven to perform transfer. It becomes possible to convey to a position.

This increases the reliability of sheet conveyance in the paper feed roller 35, and even when the interval between sheets (paper interval) is shortened, the timing of arrival at the registration roller pair 38 can be ensured. Can be improved.
In order to measure the conveyance speed of the preceding sheet S1, in this modification, a speckle pattern is detected as a feature point of the preceding sheet S1 in order to measure the conveyance speed of the preceding sheet S1, but as a feature point The leading edge of the preceding sheet S1 may be detected and the conveyance speed may be measured from the amount of movement. When both speed measurements are used in combination, first, the speed is measured from the amount of movement of the leading edge of the preceding sheet S1, and the leading edge can be detected because the preceding sheet S1 has advanced and protruded from the range of the imaging screen D. When it runs out, it should be switched to speed measurement by speckle pattern.

(2) The sheeting ability varies depending on the type of recording sheet to be conveyed, in addition to the deterioration due to the wear of the sheet feeding roller 35 and the adhesion of paper dust (see FIGS. 5 and 11).
When the sheet to be fed is high-quality paper or coated paper whose surface is smoother than plain paper, the friction coefficient between the sheets and the friction coefficient between the recording sheet and the separation roller 36 also vary. The slip start timing of 36 and the next sheet S2 are different.

  FIG. 17 is a simulation when the type of recording sheet used and the influence of paper dust adhesion are considered. In general, in the case of coated paper or the like, since the surface is smooth, the friction coefficient μ3 with the roller 36 decreases, but since the adhesion between the sheets increases, the friction coefficient μ2 between the sheets increases. In consideration of the above, it is understood that the reference sheet number as a life determination point greatly changes from the maximum n4 to n5.

  Therefore, since the number of fed sheets serving as an index for determining the life varies depending on the type of recording sheet to be used, the type of recording sheet to be used is received from the operation panel 60 from the user. In the flowchart of FIG. 12 in the second embodiment, a table corresponding to each type of recording sheet may be stored and the reference number in step S201 may be selected as appropriate.

Also, the value of the reference number is fixed to one value that is set when a standard type of recording sheet is used, and a coefficient that is converted to the standard type of supplied number is set when a different sheet is used. You may keep it.
Furthermore, in the latter case, there are two or more paper cassettes, each of which stores different types of recording sheets, and the paper feed port is changed according to the job type and user designation. The standard number of sheets is set for a standard type of recording sheet, and when a different type of sheet is used, it is multiplied by a conversion factor and integrated. You may make it perform determination of step S16 of FIG.

(3) Even if only the same type of recording sheet is used, depending on the influence of temperature and humidity changes in the usage environment of the apparatus and the length of time that the recording sheet has been stored in the paper feed cassette Depending on the amount of moisture absorption of the recording sheets, the friction coefficient μ2 between the recording sheets and the friction coefficient μ3 between the rolling roller 36 and the recording sheet may slightly vary.
As a result, the projection amount dx of the recording sheet S2 from the separation nip portion N varies, and the next sheet projection amount dx exceeds the upper limit dmax even though the separation of the separation roller 36 is not deteriorated. There is a risk of exceeding.

Under such conditions, the rolling roller 36 should be replaced immediately when the amount of protrusion of the next sheet S2 exceeds the upper limit even once, as in step S15 of FIG. 8 of the first embodiment. It is considered inappropriate to issue a warning to that effect.
Therefore, each time the recording sheet is fed, the value of the next sheet protrusion amount dx is stored and statistics are taken. If the degree of variation is a certain value or more, the protrusion amount dx is determined as a single shot. Even if the upper limit value dmax is exceeded, a warning may not be generated immediately if the roller 36 reaches the end of its life, and the warning may be issued only when the number of times exceeding the upper limit value dmax occurs continuously a plurality of times.

However, even when the next sheet protrusion amount dx reaches the detection position by the jam detection sensor 320 and the leading edge of the next sheet S2 is detected by the jam detection sensor 320, the variation tolerance is no longer exceeded. Then, since the subsequent conveyance of the recording sheet is hindered, a warning that the roller 36 should be replaced at that time may be issued.
FIG. 18 is a flowchart showing the content of the roller-roller deterioration state determination process performed by the control unit 50 in the present modification, and mainly illustrates differences from FIG. 8 in the above embodiment. Steps having the same processing contents as those in FIG. 8 are denoted by the same step numbers, and illustration and description of steps S11 to S13 and step S19 in FIG. 8 are omitted.

In this modification, the standard deviation σ is used as an index value indicating the degree of variation in the next sheet protrusion amount dx.
In step S14, each time the next sheet protrusion amount detection process is performed from the nip portion of the next sheet S2 fed when the preceding sheet S1 is operated, the protrusion amount is temporarily non-volatile. Stored in the memory 55.

In step S501, a standard deviation σ of the next sheet protrusion amount dx is obtained.
Assuming that the next sheet protrusion amount di in the i-th sheet feeding and the arithmetic average until the n-th sheet feeding is m,

で示され、分散（σ²）は、

And the variance (σ ² ) is

で表される。
上記分散σ²の正の平方根が標準偏差σになり、この値が小さいほど、次シート突出量ｄｘの検出バラツキが小さいことになる。

It is represented by
The positive square root of the variance σ ² is the standard deviation σ, and the smaller this value, the smaller the variation in detection of the next sheet protrusion amount dx.

In the next step S15, it is determined whether or not the leading edge of the next sheet S2 has exceeded the separation nip (second threshold value). If it exceeds the separation nip (YES in step S15), the amount of protrusion of the next sheet is further increased. It is determined whether dx has reached the upper limit value (step S16).
If it is determined that the next sheet protrusion amount dx has reached the upper limit value dmax (YES in step S16), it is determined whether or not the standard deviation σ obtained in step S501 is greater than or equal to a predetermined threshold σ1.

When the standard deviation σ is less than σ1 (NO in step S502), since the variation in the next sheet protrusion amount dx is small, it is determined that the influence of factors other than the deterioration of the abrasion of the winding roller 36 is small, and the process proceeds to step S18. Then, a warning message that the roller should be replaced is displayed on the display unit 62 of the operation panel 60.
On the other hand, when the standard deviation σ is equal to or greater than the threshold σ1 (YES in step S502), the variation in the next sheet protrusion amount dx is large, so it is considered that the influence of incidental factors other than the deterioration of the wear of the rolling roller 36 is large. Therefore, even if the next sheet protrusion amount dx exceeds the upper limit value about once, the next sheet protrusion amount dx is not determined to be immediately deteriorated, and the next sheet protrusion amount dx is continuously increased a predetermined number of times (for example, 10 times). Only when the value has been reached (YES in step S503), the process proceeds to step S18, and a warning message to the effect that the roller should be replaced is displayed on the display unit 62 of the operation panel 60.

  If the protrusion amount dx does not exceed the upper limit value continuously for a predetermined number of times (NO in step S503), has the leading edge of the next sheet S2 reached the jam detection position (detection position by the jam detection sensor 320)? Judgment is made (step S504), and if it has been reached (YES in step S504), there is a possibility that jams will occur repeatedly, and it is no longer possible to wait, so that the roller should be replaced in order to improve the rolling ability even a little. Is displayed on the display unit 62 of the operation panel 60 (step S18).

However, in step S504, if the leading edge of the next sheet S2 has not reached the jam detection position, the process proceeds to step S17, and a warning is displayed on the operation panel 60 that the time for replacing the roller 36 is approaching. (Step S17).
As described above, in this modification, the influence of other factors is estimated by considering the variation amount (standard deviation σ) of the next sheet protrusion amount dx, and when the variation amount is larger than a predetermined value, the next sheet protrusion amount is calculated. When dx reaches the upper limit continuously for a predetermined number of times, or when the next sheet protrusion amount dx reaches the jam detection position, whichever comes first, the replacement timing of the rolling roller 36 is warned. Thus, it is possible to accurately recognize the replacement time reflecting the deterioration state of the roller 36 itself and other factors.

As the value of the threshold σ1, an appropriate value obtained through experiments or the like is set in advance as a standard value. The value of the threshold σ1 may be configured so that the user or the like can be changed as appropriate according to the usage environment in which the copying machine 1 is actually installed.
(4) In the above embodiment, a warning message that the replacement timing of the roller roller is approaching or a warning that the roller roller should be replaced is displayed on the display unit 62 of the operation panel 60. You may warn by a warning sound or a blinking lamp.

In addition to or in place of these warning means, the control unit 50 of the copier 1 is connected to a device manager or a maintenance company terminal via a LAN, the Internet, a telephone line, or the like. It is also possible to configure such that a notification regarding the warning is transmitted to the terminal.
By doing so, maintenance such as replacement of the rolling roller can be performed promptly, the service by the maintenance company can be further improved, and downtime that occurs until the rolling roller 36 is replaced on the user side is reduced. can do.

(5) In the above embodiment, only the process for determining the deterioration of the roller 36 has been described, but it goes without saying that the paper feed roller 35 is also durable and deteriorates over time.
As described above, since priority is given to ensuring the feeding of the preceding sheet S1 in the image forming apparatus, the friction coefficient μ1 of the sheet feeding roller 35 is normally set to the largest among the friction coefficients μ1 to μ3. It is understood that.

For this reason, the replacement time of the roller 36 comes earlier than the replacement time of the paper feed roller 35, and the paper supply roller 35 is also replaced at the time of replacement of the roller 36 as described above. By doing so, the recording sheet feeding state in the sheet feeding unit 30 can always be maintained satisfactorily.
When determining the deterioration state of the paper feed roller 35 separately from the roller 36, it is effective to detect the speed at the time of passing through the roller 34 of the preceding sheet S1. When the feed roller 35 deteriorates due to wear and the friction coefficient μ1 decreases, slip occurs between the feed roller 35 and the surface of the preceding sheet S1, and the conveyance speed of the preceding sheet S1 decreases from the design value. Because it ends up. Therefore, when the amount of decrease in the speed of the preceding sheet S1 when passing through the curling unit 34 is greater than a predetermined value, a warning may be issued that it is time to replace the paper feed roller 35.

At this time, if the transport speed of the preceding sheet S1 is detected by the method described in the modification example (1-2), it is not necessary to separately provide a dedicated device for detecting the transport speed of the preceding sheet S1. The major merit is great.
(6) In the above-described embodiment, the separation unit 34 is configured by forming the separation nip portion N between the paper feed roller 35 and the separation roller 36. However, the present invention is not limited thereto, and the separation roller is a separation member. Instead of 36, it is also possible to simply use a padding pad. This is because the burning ability of the burning pad also deteriorates over time due to wear.

(7) In the above embodiment, the sheet conveying apparatus according to the present invention has been described as an example applied to the sheet feeding unit of a tandem type color copying machine. However, any image forming apparatus that performs sheet conveyance may be used. It can be applied to a facsimile machine, a printer dedicated machine, etc., and it does not matter whether it is a color or monochrome image forming apparatus.
Further, as described with reference to FIG. 1, the feeding unit in the document conveying unit 11 has the same configuration as that of the sheet feeding unit 30, so that the sheet conveying device according to the present invention is used as a document in a document reading device (image reader). You may apply to a conveying apparatus.

In short, the present invention can be applied to a sheet conveying apparatus that can carry a sheet and any apparatus including such a sheet conveying apparatus.
Moreover, you may combine the content of said each embodiment and modification as much as possible.

  The present invention is suitable as a technique for accurately grasping the deterioration state of the separation member in the separation portion of the fed sheet.

DESCRIPTION OF SYMBOLS 1 Copier 10 Scanner part 11 Document conveyance part 20 Image formation part 30 Paper feed part 31 Paper feed cassette 33 Pickup roller 34 Rolling part 35 Feeding roller 36 Rolling roller 37 Vertical conveyance roller pair 38 Registration roller pair 40 Fixing part 50 Control part 300 imaging unit 301 area sensor 302 light emitting element 310 area sensor driving unit 320 jam detection sensor S1 preceding sheet S2 next sheet E leading edge of next sheet Es shadow of leading edge of next sheet on surface of preceding sheet

Claims (14)

A sheet conveying device that feeds and conveys a sheet from a sheet storage unit,
A means for rolling the preceding sheet and the next sheet by forming a nip portion by bringing a rolling member into contact with the peripheral surface of the paper feeding roller, passing the sheet fed out from the sheet storage portion and passing it through the nip portion When,
A protrusion amount detection means for detecting a protrusion amount of the leading edge of the next sheet, which has been stopped by the rolling means, from the rolling nip portion;
Determination means for determining the deterioration state of the rolling member based on the protrusion amount detected by the protrusion amount detection means;
Warning means for issuing a warning according to the deterioration state determined by the determination means;
Equipped with a,
The determination means determines that the rolling member has deteriorated when the amount of protrusion of the next sheet exceeds a first threshold, and the warning means warns that the rolling member should be replaced,
A counter for accumulating and counting the number of conveyed sheets is further provided.
If the protrusion amount exceeds the first threshold before the count value by the counter reaches a predetermined value, the determination means determines that the main cause of the rolling failure is the contact with the paper feed roller of the winding member. A sheet conveying apparatus, characterized in that it is determined that the paper dust adhered to the contact surface is present, and the warning means warns that the paper dust on the peripheral surface of the rolling roller should be cleaned . A sheet conveying device that feeds and conveys a sheet from a sheet storage unit,
A means for rolling the preceding sheet and the next sheet by forming a nip portion by bringing a rolling member into contact with the peripheral surface of the paper feeding roller, passing the sheet fed out from the sheet storage portion and passing it through the nip portion When,
A protrusion amount detection means for detecting a protrusion amount of the leading edge of the next sheet, which has been stopped by the rolling means, from the rolling nip portion;
Determination means for determining the deterioration state of the rolling member based on the protrusion amount detected by the protrusion amount detection means;
Warning means for issuing a warning according to the deterioration state determined by the determination means;
With
The determination means determines that the rolling member has deteriorated when the amount of protrusion of the next sheet exceeds a first threshold, and the warning means warns that the rolling member should be replaced,
When the protrusion amount exceeds a second threshold value that is smaller than the first threshold value, the determination unit determines that the timing for replacing the scooping member is reached after feeding a predetermined number of sheets, and the warning unit indicates that Warning
A sheet conveying apparatus. A sheet conveying device that feeds and conveys a sheet from a sheet storage unit,
A means for rolling the preceding sheet and the next sheet by forming a nip portion by bringing a rolling member into contact with the peripheral surface of the paper feeding roller, passing the sheet fed out from the sheet storage portion and passing it through the nip portion When,
A protrusion amount detection means for detecting a protrusion amount of the leading edge of the next sheet, which has been stopped by the rolling means, from the rolling nip portion;
Determination means for determining the deterioration state of the rolling member based on the protrusion amount detected by the protrusion amount detection means;
Warning means for issuing a warning according to the deterioration state determined by the determination means;
With
The protrusion amount detection means includes an image pickup means for picking up an image of a predetermined range of the sheet surface including a position corresponding to the separation nip portion in the sheet conveyance direction using an area sensor;
And a calculation means for detecting the position of the leading edge of the next sheet based on the image data obtained by the imaging means and calculating the amount of protrusion of the leading edge of the next sheet from the nip portion,
The imaging means is arranged to take an image of a range shifted in the main scanning direction by a predetermined distance from the rolling member in the rolling means,
The protrusion amount detection means acquires an inclination amount with respect to the main scanning direction of the leading edge of the next sheet rolled by the rolling means based on the image data obtained by the imaging means, and the image pickup means and the rolling member Based on the distance in the main scanning direction and the amount of inclination, the amount of protrusion of the next sheet from the sheeting nip at the axial center of the sheeting member is obtained.
A sheet conveying apparatus. A sheet conveying device that feeds and conveys a sheet from a sheet storage unit,
A means for rolling the preceding sheet and the next sheet by forming a nip portion by bringing a rolling member into contact with the peripheral surface of the paper feeding roller, passing the sheet fed out from the sheet storage portion and passing it through the nip portion When,
A protrusion amount detection means for detecting a protrusion amount of the leading edge of the next sheet, which has been stopped by the rolling means, from the rolling nip portion;
Determination means for determining the deterioration state of the rolling member based on the protrusion amount detected by the protrusion amount detection means;
Warning means for issuing a warning according to the deterioration state determined by the determination means;
With
The protrusion amount detection means includes an image pickup means for picking up an image of a predetermined range of the sheet surface including a position corresponding to the separation nip portion in the sheet conveyance direction at a predetermined frame rate using an area sensor;
Based on a plurality of image data obtained by the imaging means, it is determined whether or not the position of the leading edge of the next sheet is moved. If it is determined that there is no movement, the leading edge of the next sheet at that time is determined. And a calculation means for calculating the amount of protrusion from the rolling nip portion.
A sheet conveying apparatus. The determining means determines that the rolling member has deteriorated when the amount of protrusion of the next sheet exceeds a first threshold, and the warning means warns that the rolling member should be replaced. The sheet conveying apparatus according to claim 3 or 4 . A counter for accumulating and counting the number of conveyed sheets is further provided.
If the protrusion amount exceeds the first threshold before the count value by the counter reaches a predetermined value, the determination means determines that the main cause of the rolling failure is the contact with the paper feed roller of the winding member. The sheet conveying device according to claim 2 or 5 , wherein the sheet conveying device determines that the paper dust adhered to the contact surface is present, and the warning means warns that the paper dust on the peripheral surface of the roller is to be cleaned. . When the protrusion amount exceeds a second threshold value that is smaller than the first threshold value, the determination unit determines that the timing for replacing the scooping member is reached after feeding a predetermined number of sheets, and the warning unit indicates that The sheet conveying apparatus according to claim 1 , wherein the sheet conveying apparatus is a warning. The protrusion amount detection means includes an image pickup means for picking up an image of a predetermined range of the sheet surface including a position corresponding to the separation nip portion in the sheet conveyance direction using an area sensor;
And a calculating means for detecting the position of the leading edge of the next sheet based on the image data obtained by the imaging means and calculating the amount of protrusion of the leading edge of the next sheet from the nip portion. Item 3. The sheet conveying apparatus according to Item 1 or 2 . The image pickup means continues the image pickup from a point in time when the predetermined time has elapsed from the start of operation of the preceding sheet until at least the movement of the leading edge of the next sheet stopped is stopped . The sheet conveying apparatus according to any one of 4 and 8 . The imaging means is arranged to take an image of a range shifted in the main scanning direction by a predetermined distance from the rolling member in the rolling means,
The protrusion amount detection means acquires an inclination amount with respect to the main scanning direction of the leading edge of the next sheet rolled by the rolling means based on the image data obtained by the imaging means, and the image pickup means and the rolling member 9. The sheet conveying apparatus according to claim 4 , wherein the amount of protrusion of the next sheet from the sheeting nip portion at the axial center of the sheeting member is obtained based on the distance in the main scanning direction and the amount of inclination. Based on the image data obtained by the imaging means, the leading edge of the preceding sheet separated from the next sheet by the rolling means, or the image of the preceding sheet surface between the leading edge of the preceding sheet and the leading edge of the next sheet A conveyance speed acquisition unit that detects the characteristic pattern of the first sheet and acquires the conveyance speed of the preceding sheet;
Speed control means for controlling the rotational speed of the paper feed roller based on the acquired transport speed;
Sheet conveying apparatus according to any one of claims 3,4,8, characterized by further comprising a. Every time the sheet is fed out from the sheet storage unit, the amount of protrusion from the rolled nip portion of the next sheet fed is statistically provided, and a variation degree calculating means for calculating the variation degree is provided.
The determination means includes
When the degree of variation exceeds a predetermined threshold, the amount of protrusion of the next sheet exceeds the first threshold several times in succession, or a third threshold that is larger than the first threshold is 1 The sheet conveying device according to any one of claims 1 to 11 , wherein the sheet conveying device is determined to be in a state in which the rolling member should be replaced at the earlier time point of exceeding the number of times. An original reading apparatus comprising the sheet conveying apparatus according to claim 1 as an original conveying apparatus. An image forming apparatus comprising the sheet conveying apparatus according to claim 1 as a recording sheet conveying apparatus.

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