JP2001151385A - Sheet conveytng device of image forming machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveying device of an image forming machine capable of certainly determining that a conveying capability decreases to a predetermined speed before performance of the image forming machine is damaged. SOLUTION: This sheet conveying device of the image forming machine comprises a sheet conveying passage formed through an image transfer region and a conveying roller disposed in the sheet conveying passage. The sheet conveying device comprises a sheet detecting sensor disposed in the sheet conveying passage for detecting the sheet conveyed by the conveying roller, and a control means that determines a sheet passing time based on a detection signal from the sheet detecting sensor, calculates a sheet conveying speed based on the sheet passing time, and determines that the conveying capability of the conveying roller decreases when the sheet conveying speed is lower than the predetermined speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a sheet conveying device for an image forming machine such as a laser beam printer and an electrostatic copying machine.

[0002]

2. Description of the Related Art In an image forming apparatus of this type, a transport roller is provided in a paper transport path formed through an image transfer section, and the transport roller transports a sheet as a transfer material through the image transfer section. Equipment. The transport roller is generally made of synthetic rubber such as urethane rubber. The transport roller made of such a synthetic rubber has a reduced transport capability due to wear due to use and adhesion of paper dust and the like, and the transport speed of the paper is reduced. When the paper transport speed of the transport roller decreases, the image forming time increases, and in the case where the transport roller having reduced transport capability is a registration roller disposed upstream of the image transfer unit,
There is a problem that the image transfer position on the paper is shifted.

[0003]

The determination of whether or not the transporting ability of the transporting roller is reduced can be made by an operator by visually checking the deviation of the image transfer position or by increasing the image forming time. Was judged intuitively. Therefore, it is difficult to detect this unless the transporting ability of the transporting roller is reduced to a point where the performance of the image forming apparatus is hindered. Therefore, in the past, when used until the transport capacity of the transport roller was reduced to the point where the performance of the image forming machine was hindered, it was determined that the transport roller had reached the end of its service life, and the transport roller was replaced or the peripheral units were replaced. Was. However, the lowering of the transporting ability of the transporting roller is greatly affected by the adhesion of paper dust and the like, and the adhering paper dust and the like are removed when the transporting ability decreases to a predetermined speed before hindering the performance of the image forming machine. By doing so, the conveying roller can recover the predetermined conveying ability. Further, at the time when the transport capacity has decreased to a predetermined speed before the performance of the image forming apparatus is hindered, the desired transport speed can be maintained by increasing the rotation speed of the transport rollers.

[0004] The present invention has been made in view of the above-mentioned facts, and a first technical problem is that the conveyance capability is reduced to a predetermined speed before the performance of the image forming machine is hindered. It is an object of the present invention to provide a sheet conveying device of an image forming machine capable of making a reliable determination.

Further, a second technical problem of the present invention is to provide a warning to an operator when the conveyance capacity is reduced to a predetermined speed before the performance of the image forming apparatus is hindered, and to clean the conveyance rollers. To provide a sheet conveying device of an image forming machine capable of prompting the user.

Further, a third technical problem of the present invention is to increase the rotation speed of the transport roller when the transport capacity decreases to a predetermined speed before the performance of the image forming apparatus is impaired.
An object of the present invention is to provide a sheet conveying device of an image forming machine that can maintain a conveying speed of a conveying roller within a predetermined range.

[0007]

According to the present invention, there is provided a paper conveying path formed through an image transfer area to achieve the first technical problem. In a sheet conveying device of an image forming machine having a conveying roller disposed on a sheet conveying path, a sheet detecting sensor disposed on the sheet conveying path and detecting a sheet conveyed by the conveying roller, and the sheet detecting sensor The time required for the paper to pass based on the detection signal from is calculated, and the paper transport speed is calculated from the travel time of the paper. If the paper transport speed is lower than the predetermined speed, the transport capability of the transport roller is reduced. And a control unit for determining that there is a sheet conveying device of the image forming apparatus.

According to the present invention, in order to achieve the second technical problem, an image having a paper transport path formed through an image transfer area and a transport roller disposed in the paper transport path is provided. In a paper transport device of a forming machine, a paper detection sensor that is disposed in the paper transport path and detects a paper transported by the transport roller, and a display unit that indicates that the transport capability of the transport roller is reduced. Calculating the paper transport speed based on a detection signal from the paper detection sensor, and calculating the paper transport speed. If the paper transport speed is slower than a predetermined speed, the display means displays the transport capability of the transport roller. And a control unit for displaying that the sheet is being processed.

Further, according to the present invention, in order to achieve the third technical object, a paper transport path formed through an image transfer area, a transport roller disposed in the paper transport path,
In a sheet conveying device of an image forming machine having an electric motor for rotationally driving the conveying roller, a sheet detecting sensor disposed on the sheet conveying path and detecting a sheet conveyed by the conveying roller, Control means for calculating a sheet conveying speed by calculating a time for the sheet to pass based on a detection signal from the sensor, and increasing the rotation speed of the electric motor when the sheet conveying speed is lower than a predetermined speed. A sheet conveying device for an image forming machine is provided.

Further, according to the present invention, there is provided a paper transport path formed through an image transfer area, a transport roller disposed in the paper transport path, and an electric motor for rotating the transport roller. In a sheet conveying device of an image forming machine,
A sheet detection sensor disposed in the sheet conveyance path for detecting a sheet conveyed by the conveyance roller, a display unit for displaying that the conveyance capability of the conveyance roller is reduced, and a detection from the sheet detection sensor Control means for controlling the rotation speed of the electric motor based on the signal and controlling the display means, wherein the control means determines a time for the paper to pass based on a detection signal from the paper detection sensor. The paper transport speed is calculated, and when the paper transport speed is equal to or lower than the predetermined speed, the rotation speed of the electric motor is increased, and when the number of times to increase the rotation speed of the electric motor reaches the predetermined number, or when the increase speed is increased. When the predetermined value is reached, a display is provided on the display unit to indicate that the transport capacity of the transport roller has decreased, thereby providing a paper transport apparatus for an image forming machine. Other objects and features of the present invention will become apparent from the following description.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an image forming apparatus provided with a sheet conveying device according to the present invention;

FIG. 1 is a schematic cross-sectional view of a laser beam printer as an image forming machine having a paper transport device configured according to the present invention. The illustrated laser beam printer includes an image forming machine main body 100 and a reversing sheet feeding unit 200 that can be optionally attached to the image forming machine main body 100. Image forming machine body 10
Numeral 0 includes a rectangular parallelepiped housing 101 formed of a synthetic resin. At a substantially central portion of the housing 101, a front and rear side plate made of a metal plate (not shown) disposed at a predetermined interval in the front-rear direction (a direction perpendicular to the plane of FIG. 1) in the housing 101 is provided. A photosensitive drum 104 is rotatably provided. The photoreceptor drum 104 is driven to rotate by a gear transmission (not shown) in the direction indicated by an arrow 105 sequentially through a charging area, an electrostatic latent image forming area, a developing area, an image transfer area, and a cleaning area. Around the photosensitive drum 104, a charging corona discharger 106 is provided in a charging area, and the developing device 1 is provided in a developing area.
08, transfer roller 11 as transfer device in image transfer area
0, a cleaning device 112 is provided in the cleaning area.

The charging corona discharger 106 charges the photosensitive layer mounted on the peripheral surface of the photosensitive drum 104 to a specific polarity. The developing device 108 includes, in the illustrated embodiment, a developing roller and a stirring means disposed in a developing housing for accommodating a developer composed of a one-component toner. The electrostatic latent image formed on the surface is developed into a toner image. A toner cartridge 114 containing replenished toner is detachably mounted above the developing device 108, and is replenished sequentially when a predetermined amount of toner in the developing device 108 is consumed. The transfer roller 110 is formed of, for example, conductive urethane foam, is rotatably supported by the front and rear side plates, and is driven to rotate in a direction indicated by an arrow by a gear transmission (not shown). Note that a constant current of, for example, about 10 μA is applied to the transfer roller 10. The cleaning device 112 includes a cleaning fur brush, a cleaning blade, and the like, and removes toner remaining on the peripheral surface of the photosensitive drum 104.

A laser unit 116 as an electrostatic latent image forming device is disposed above the housing 102, that is, above the photosensitive drum 104. The laser unit 116 projects, for example, a laser beam based on image information output from a computer on the peripheral surface of the photosensitive drum 104 in the electrostatic latent image forming area.

In the housing 101, there is provided a sheet conveying device for conveying a sheet through the image transfer area. The paper transport device includes a paper transport path 120 formed through the image transfer area from the right side to the upper left side in FIG. A pair of paper feed rollers 122 and a pair of registration rollers 124 as transport rollers for transporting the paper are disposed upstream of the image transfer area in the paper transport path 120. The paper feed roller pair 122 includes a drive roller 122a made of synthetic rubber such as urethane rubber and a driven roller 122b made of an appropriate synthetic resin. The drive roller 122a is driven by an electric motor 123 (M1). For example, 262 mm /
It is rotated at the transport speed of sec. The registration roller pair 124 includes a drive roller 124a made of a synthetic rubber such as urethane rubber and a driven roller 124b made of an aluminum alloy. The drive roller 124a is driven by an electric motor 125 (M2) at, for example, 134 mm /. It is rotated at the transport speed of sec.
A fixing roller pair 126, a conveying roller pair 128, a branch claw 130, and a discharge roller pair 132 which constitute a fixing device are provided downstream of the image transfer area in the sheet conveying path 120.
Are arranged. Each of the roller pairs 128 is rotationally driven by an electric motor and a driving mechanism (not shown). The branching claw 130 is configured to be operable at a first position indicated by a solid line and a second position indicated by a two-dot chain line in FIG. 1, and is operated by an electromagnetic solenoid (not shown). When the branching claw 130 is positioned at the first position shown by the solid line, the sheet transported by the transporting roller pair 128 is sent toward the discharge roller pair 132, and the branching claw 130 is moved to the second position shown by the two-dot chain line. When the sheet is positioned at the position, the sheet conveyed by the conveying roller pair 128 is sent toward the double-sided image forming outlet 102.

A cassette accommodating section is provided below the sheet conveying path 120, and a sheet cassette 134 is removably mounted in the cassette accommodating section. The paper stored in the paper cassette 134 is fed by the feed roller pair 12 by the feed roller 136 and the separation roller pair 138.
Sent to 2 The feed roller 136 and the separating roller pair 138 are rotated at a transport speed of 262 mm / sec by an electric motor and a driving mechanism (not shown), for example, similarly to the paper feed roller pair 122. At the right end of the paper cassette 134 in the drawing, a paper insertion passage 135 that is open to face the paper feed roller pair 122 when mounted on the housing 101 is provided. A lower portion of the housing 101, that is, a lower portion of the cassette housing portion, accommodates a later-described control unit 400 for controlling the operation of the components of the image forming apparatus main body 100 and the components of the reversing sheet feeding unit 200 described later. Is provided. This device housing part 14
0, a paper insertion path 14 communicating with a paper insertion path 135 provided in the paper cassette 134 is provided at the right end.
1 is provided.

The image forming machine main body 1 configured as described above.
A plurality of paper detection sensors for detecting the passage of paper and a paper jam (jam) are disposed in the paper transport path 120 of 00. That is, a paper detection sensor 151 (SW) is provided between the separation roller pair 138 and the paper feed roller pair 122.
I) is disposed, and a paper detection sensor 152 (SW2) is disposed between the paper feed roller pair 122 and the registration roller pair 124. A paper detection sensor 153 (SW3) is provided between the image transfer area where the transfer roller 10 is provided and the fixing roller pair 126, and a paper sheet is provided between the fixing roller pair 126 and the transport roller pair 128. Detection sensor 154
(SW4) is provided. It should be noted that a well-known detector such as a micro switch or a photo interrupter can be used as these paper detection sensors. Paper detection sensor 15
1 (SWI), 152 (SW2), 153 (SW3),
154 (SW4) sends the detection signal to the control means 400.

The image forming machine main body 1 in the illustrated embodiment.
00 is configured as described above, and its operation will be described below. While the photosensitive drum 104 is rotated in the direction indicated by the arrow 105, the charging corona discharger 106 charges the photosensitive layer of the photosensitive drum 104 to a specific polarity. Next, a laser light source (not shown) of the laser unit 116 in an electrostatic latent image forming area between the charging area where the charging corona discharger 106 is provided and the developing area where the developing device 108 is provided. The laser light is projected onto the photosensitive drum 104, and an electrostatic latent image corresponding to the image information is formed on the peripheral surface of the photosensitive drum 104. Thereafter, the developing device 10
The developing roller 8 applies toner to the electrostatic latent image on the photosensitive drum 104 to develop the electrostatic latent image into a toner image.
On the other hand, the delivery roller 13 from the paper cassette 134
6 and the paper fed by the separation roller pair 138 are conveyed by the paper supply roller pair 122 and temporarily stopped by the registration roller pair 124, and the photoconductor drum 104 and the transfer roller 110 are The sheet is transported to the opposite transfer area. The toner image formed on the peripheral surface of the photosensitive drum 104 is transferred to the surface of the sheet conveyed to the transfer area by the operation of the transfer roller 110.

The sheet on which the toner image has been transferred is peeled off from the photosensitive drum 104, and is then conveyed to a fixing roller pair 126, where the toner image is heated and fixed on the surface of the sheet by the action of the fixing roller pair 126. The sheet on which the toner image is fixed is discharged to a receiving portion 103 formed on the housing 101 via a pair of conveying rollers 128 and a pair of discharging rollers 132. When forming images on both sides of the paper,
The branch claw 130 is located at the second position shown by a two-dot chain line in FIG. 1. Therefore, the sheet on which the toner image is fixed by the operation of the fixing roller pair 126 passes through the conveying roller pair 128 to form a two-sided image. To the outlet 102. On the other hand, the photosensitive drum 104 further continues to rotate, and the residual toner is removed from the surface of the photosensitive drum 104 by the action of the cleaning device 112.

Next, the reversing sheet feeding unit 200 will be described. Reverse sheet feeding unit 20 in the illustrated embodiment
Reference numeral 0 denotes an L-shaped unit housing 201, which comprises a sheet reversing unit 210 and a double-sided paper feeding unit 250 provided in the unit housing 201. In addition,
The sheet reversing unit 210 and the duplex sheet feeding unit 250 function as a sheet conveying device. The sheet reversing unit 210 includes a sheet reversing conveyance path 212 formed in communication with the two-sided image forming discharge port 102, a conveyance roller pair 214 disposed on the reversing conveyance path 212, and a sheet reversing roller pair 216. A sheet change guide plate 21 disposed along the sheet reversing roller pair 216.
8 is provided. The sheet reversing conveyance path 212 is a sheet conveyance path 212a that communicates with the two-sided image forming discharge port 102.
And a paper reversing path 212b formed continuously with the paper carrying path 212a and extending to the bottom wall of the unit housing 201. The transport roller pair 214 is a drive roller 214a made of synthetic rubber such as urethane rubber.
And a driven roller 21 made of an aluminum alloy
4b, and is disposed in the paper carry-in path 212a. The sheet reversing roller pair 216 functioning as a transport roller also includes a driving roller 216a made of synthetic rubber such as urethane rubber and a driven roller 216b made of an aluminum alloy. It is arranged between the road 212b. The driving rollers 214a and 216a of the transport roller pair 214 and the sheet reversing roller pair 216 are driven to rotate by an electric motor 215 (M3). The electric motor 215 (M3) is configured to be able to rotate forward and reverse. When the electric motor 215 (M3) is driven to rotate forward, the driving roller 2 of the sheet reversing roller pair 216 is driven.
16a is rotated in the direction indicated by arrow 217a, and when the electric motor 215 (M3) is driven to rotate in the reverse direction, the drive roller 216a of the sheet reversing roller pair 216 is rotated in the direction indicated by arrow 217b. The electric motor 215
(M3) is the driving roller 21 of the sheet reversing roller pair 216.
When rotating 6a in the direction indicated by arrow 217b, it is rotated at a transport speed of, for example, 262 mm / sec.

The paper reversing section 210 constructed as described above
A sheet detection sensor 1 for detecting the passage of a sheet and a paper jam (jam) between the pair of conveyance rollers 214 and the pair of sheet reversing rollers 216 in the sheet reversal conveyance path 212 of FIG.
55 (SW5) are provided. The paper detection sensor 155 (SW5) sends a detection signal to the control unit 400.

Next, a description will be given of the double-sided paper feeding unit 250 constituting the reversing paper feeding unit 200. In the illustrated embodiment, the two-sided paper feed unit 250 is provided with the paper change guide plate 218.
And a pair of transport rollers 254, 25 disposed in the paper transport path 252.
6, 258. These transport roller pairs 25
4, 256 and 258 are electric motors 260 (M4)
Is rotated in the direction shown by the arrow, and the paper fed from the paper reversing unit 210 is fed to the paper insertion path 141 provided in the equipment housing section 140 and the paper cassette 1.
The sheet is conveyed toward the sheet feed roller pair 122 through a sheet insertion passage 135 provided in the sheet feed roller. Also, the paper transport path 25
2, the paper change guide plate 218 and the transport roller pair 254
A paper detection sensor 156 (SW6) for detecting the passage of a paper and a paper jam (jam) is disposed between them. This paper detection sensor 156 (SW6)
The detection signal is sent to the control means 400. At the right end of the unit housing 201 in the drawing, a paper insertion path 202 communicating with the paper insertion path 141 provided in the device housing section 140 is provided. This sheet insertion path 202
When another paper cassette is disposed below the duplex paper supply unit 250, the paper feed path functions as a transport path for the paper fed from the paper cassette.

Here, the above-described reversing sheet feeding unit 200
The operation of will be described. When forming an image on the other side of the sheet on which an image is formed on one side by the image forming machine main body 100, the branching claw 130 is indicated by a two-dot chain line.
Is transported by the pair of transport rollers 128 and is carried into the paper carrying path 212 a of the paper reversing carrying path 212 through the discharge port 102 for double-sided image formation. When the sheet is carried into the sheet reversing conveyance path 212, the leading edge of the sheet is detected by the sheet detection sensor 154 (SW4).
Through the sheet detection sensor 154 (SW
4) is turned on, and the control means 4 is turned on based on the ON signal.
00 drives the electric motor 215 (M3) forward. Accordingly, the sheet carried into the sheet carrying path 212a is carried to the sheet reversing path 212b by the pair of carrying rollers 214 and the pair of sheet reversing rollers 216. When the trailing edge of the sheet conveyed toward the sheet reversing path 212b passes through the sheet detection sensor 155 (SW5), the control unit 4 detects the rear end of the sheet based on the detection signal from the sheet detection sensor 155 (SW5).
00 is a predetermined time (the trailing edge of the paper is
(SW5) and the sheet reversing roller pair 216
The electric motor 215 (M3) is driven to rotate in the reverse direction after the elapse of the time required to reach immediately before the nip portion. As a result, the sheet is sent out from the sheet reversing roller pair 216 with the front and back reversed. At this time, the sheet is guided by the sheet change guide plate 218, turned over, and conveyed toward the sheet conveying path 252. The paper transported toward the paper transport path 252 is transported by a pair of transport rollers 2.
The paper feed roller pair 122 is transported rightward in FIG. 1 by the paper feed rollers 54, 256, and 258, and passes through the paper insertion path 141 provided in the equipment housing section 140 and the paper insertion path 135 provided in the paper cassette 134.
Conveyed toward.

Next, the control means 400 will be described with reference to FIG.
This will be described with reference to FIG. The control means 400 is constituted by a microcomputer, and has a central processing unit (CPU) 401 for performing arithmetic processing according to a control program, and a read-only memory (ROM) for storing the control program.
402, a readable and writable random access memory (RAM) 403 for storing calculation results and the like, and a timer (T) 4
04, an input interface 405 and an output interface 406. The input interface 405 includes the paper detection switch 151 (SW1),
152 (SW2), 153 (SW3), 154 (SW
4) In addition to 155 (SW5) and 156 (SW6),
A detection signal from various detecting units provided in the image forming apparatus main body 100, a control signal from a computer connected to the image forming apparatus main body 100, and the like are input. The output interface 406 outputs the electric motor 123 (M
1), 125 (M2), 215 (M3), 260 (M
4) and outputs a control signal to each operating device of the image forming machine main body 100, in addition to the display means 270 provided on the operation panel of the image forming machine main body 100.

Each transport roller in the paper transport device of the image forming machine main body 100 and the reversing paper feed unit 200 has a reduced transport capability due to wear due to use and adhesion of paper dust. In particular, the paper feed roller pair 1 of the respective transport rollers
22, the pair of registration rollers 124 and the pair of sheet reversing rollers 216 have a significant effect on the performance of the image forming machine due to a reduction in the carrying capacity. Accordingly, the following describes the determination of a decrease in the transporting capability and the subsequent measures regarding the sheet feeding roller pair 122, the registration roller pair 124, and the sheet reversing roller pair 216 with reference to the flowcharts shown in FIGS.

First, a description will be given, with reference to the flowchart shown in FIG. 3, of the determination of a decrease in the transporting ability of the pair of sheet feeding rollers 122, the pair of registration rollers 124, and the pair of sheet reversing rollers 216. In the illustrated embodiment, first, steps S1 to S6 are executed to execute the sheet feeding roller pair 122.
Is determined as to a decrease in the transport capacity of the vehicle. Control means 400
Indicates that the sheet detection switch 151 (S
W1) is ON or not, ie, the paper cassette 134
Of the sheet fed by the feed roller 136 and the separating roller pair 138 from the sheet feed switch 151
It is checked whether (SW1) has been passed. If the paper detection switch 151 (SW1) is not turned on, the process waits. If the paper detection switch 151 (SW1) is turned on, it is determined that the leading edge of the paper has passed the paper detection switch 151 (SW1). Then, the timer (T) 404 starts counting time. And the control means 40
In step S3, the process proceeds to step S3, where the sheet detection switch 151 (S
It is checked whether or not W1) has been turned off, that is, whether or not the rear end of the sheet has passed the sheet detection switch 151 (SW1). If the paper detection switch 151 (SW1) is not turned off, the control waits until the paper detection switch 151 (SW1) is turned off.
F, the trailing edge of the paper is detected by the paper detection switch 151 (S
When it is determined that W1) has been passed, the control means 400 proceeds to step S4 and ends the time measurement of the timer (T) 404. Next, the control means 400 proceeds to step S5, and based on the elapsed time from the start of timing of the timer (T) 404 to the end of timing and the length in the transport direction based on the sheet size, the control of the sheet feeding roller pair 12 is performed.
The second sheet transport speed (VA) is calculated. Then, the control means 400 proceeds to step S6, where the paper feed roller pair 122
It is checked whether or not the paper transport speed (VA) is equal to or lower than the predetermined speed (VI). Note that the predetermined speed (VI) is set at the set conveyance speed of the sheet feeding roller pair 122 (262 mm / sec).
For example, it is set to 249 mm / sec which is 5% slower than c). In step S6, as a result of comparing the sheet conveying speed (VA) of the sheet feeding roller pair 122 with the predetermined speed (VI), if the sheet conveying speed (VA) of the sheet feeding roller pair 122 is lower than the predetermined speed (VI). The control means 400 determines that it is difficult to maintain the predetermined performance of the image forming apparatus due to a decrease in the transporting ability of the pair of paper feed rollers 122, and proceeds to step S7 to display on the operation panel of the image forming apparatus main body 100. The information is displayed on the display means 270 provided. From this display, the operator knows that the transport capacity of the paper feed roller pair 122 has decreased, and cleans the paper feed roller pair 122,
The conveyance ability of the sheet feeding roller pair 122 is restored.

In step S6, the sheet feeding roller pair 1
As a result of comparing the sheet conveying speed (VA) of the sheet feed roller pair 122 with the predetermined speed (VI), the sheet conveying speed (V
If A) is higher than the predetermined speed (VI), the control means 4
In the case of 00, it is determined that the transporting ability of the sheet feeding roller pair 122 is maintaining the predetermined performance, and the process proceeds to step S8. Then, the control unit 400 performs steps S8 to S1.
3 is executed to judge whether the conveyance ability of the registration roller pair 124 has been reduced. The control unit 400 checks in step S8 whether the paper detection switch 153 (SW3) has been turned ON, that is, whether the leading edge of the paper conveyed by the registration roller pair 124 has passed the paper detection switch 153 (SW3). I do. Paper detection switch 153
If (SW3) is not ON, wait until the paper detection switch 1
If 53 (SW3) is turned ON, it is determined that the leading end of the sheet has passed the sheet detection switch 153 (SW3), and the control means 400 proceeds to step S9 to start time counting by the timer (T) 404. Then, the control means 400 determines in step S
Proceeding to 10, the paper detection switch 153 (SW3) is turned off.
F, ie, the trailing edge of the paper is
3 (SW3) is checked. If the paper detection switch 153 (SW3) is not turned off, wait.
If the paper detection switch 153 (SW3) is turned off, it is determined that the trailing edge of the paper has passed the paper detection switch 153 (SW3), and the control unit 400 proceeds to step S11 to end the time measurement of the timer (T) 404. . Next, the control means 400 proceeds to step S12, where the timer (T) 40
The paper transport speed (VA) of the registration roller pair 124 is calculated from the elapsed time from the start of the timing to the end of the timing and the length in the transport direction based on the paper size. And the control means 40
In step S13, the process proceeds to step S13.
It is checked whether the paper transport speed (VB) is equal to or lower than the predetermined speed (V2). Note that the predetermined speed (V2) is set at the set conveyance speed of the registration roller pair 124 (134 mm / s).
For example, it is set to 140.7 mm / sec which is 3% slower than ec). In step S13, as a result of comparing the sheet conveying speed (VB) of the pair of registration rollers 124 with the predetermined speed (V2), if the sheet conveying speed (VB) of the pair of registration rollers 124 is equal to or lower than the predetermined speed (V2), control is performed. The unit 400 determines that it is difficult to maintain the predetermined performance of the image forming apparatus due to a decrease in the transporting ability of the registration roller pair 124, and proceeds to step S7 to proceed to step S7.
0 is displayed on the display means 270 provided on the operation panel 0. This display allows the operator to register the pair of registration rollers.
24, the registration roller pair 124 is cleaned, and the registration roller pair 12 is cleaned.
4 is restored.

In step S13, the sheet conveying speed (VB) of the registration roller pair 124 and the predetermined speed (V2)
As a result of the comparison, when the paper conveyance speed (VB) of the registration roller pair 124 is higher than the predetermined speed (V2), the control unit 400 determines that the conveyance capability of the registration roller pair 124 maintains the predetermined performance. And step S14
Proceed to. Then, the control unit 400 executes steps S14 to S19 to determine whether the conveyance capacity of the sheet reversing roller pair 216 has decreased. The control means 400
In step S14, the paper detection switch 156 (SW
6) is turned ON, that is, the leading edge of the sheet conveyed by the sheet reversing roller pair 216 is detected by the sheet detection switch 156.
It is checked whether (SW6) has been passed. If the paper detection switch 156 (SW6) is not turned on, the process waits. If the paper detection switch 156 (SW6) is turned on, it is determined that the leading edge of the paper has passed the paper detection switch 156 (SW6). Then, the timer (T) 404 starts counting time. And control means 4
00 proceeds to step S16, and the sheet detection switch 156
It is checked whether or not (SW6) is turned off, that is, whether or not the rear end of the sheet has passed the sheet detection switch 156 (SW6). Paper detection switch 156 (SW6) is OFF
If not, wait until the paper detection switch 156 (SW6) is turned off.
(SW6), the control means 400 proceeds to step S17 and ends the time measurement of the timer (T) 404. Next, the control means 400 proceeds to step S18,
The paper transport speed (VC) of the pair of paper reversing rollers 216 is calculated from the elapsed time from the start of timing to the end of timing of the timer (T) 404 and the length in the transport direction based on the paper size. Then, the control unit 400 proceeds to step S19, and checks whether or not the sheet conveying speed (VC) of the sheet reversing roller pair 216 is equal to or lower than the predetermined speed (V3). The predetermined speed (V3) is, for example, 249 m which is 5% slower than the set conveyance speed (262 mm / sec) of the pair of sheet reversing rollers 216.
m / sec. In step S18, as a result of comparing the sheet conveying speed (VC) of the pair of sheet reversing rollers 216 with the predetermined speed (V3), the pair of sheet reversing rollers 21
If the sheet conveying speed (VC) of No. 6 is equal to or lower than the predetermined speed (V3), the control means 400 has difficulty in maintaining the predetermined performance of the image forming machine because the conveying capability of the pair of sheet reversing rollers 216 is reduced. It is determined that there is, and the process proceeds to step S7, where the display unit 2 provided on the operation panel of the image forming apparatus main body 100 is displayed.
70 is displayed. From this display, the operator knows that the transport capability of the pair of sheet reversing rollers 216 has decreased, and cleans the pair of sheet reversing rollers 216, thereby recovering the transport capability of the pair of sheet reversing rollers 216. In step S19, as a result of comparing the sheet conveying speed (VC) of the sheet reversing roller pair 216 with the predetermined speed (V3), the sheet conveying speed (VC) of the sheet feeding roller pair 122 is determined to be the predetermined speed (V3).
3) If the speed is higher, the control means 400 determines that the transport capability of the sheet reversing roller pair 216 maintains the predetermined performance, returns to step S1, and repeats the above steps S1 to S19.

Next, a description will be given, with reference to the flow chart shown in FIG. 4, of the determination of a decrease in the transporting ability of the pair of sheet feeding rollers 122, the pair of registration rollers 124, and the pair of sheet reversing rollers 216 and the subsequent measures.

In the illustrated embodiment, first, Steps P1 to P6 are executed to judge whether or not the conveyance capacity of the sheet feeding roller pair 122 has decreased. Step P1
Steps P6 to P6 are the same as steps S1 to S6 described above, and a description thereof will be omitted. As a result of executing Steps P1 to P6 and comparing the transport speed (VA) of the paper feed roller pair 122 with the predetermined speed (VI),
When the transport speed (VA) of the paper feed roller pair 122 reaches a predetermined speed (V
I) If not, the control unit 400 determines that it is difficult to maintain the predetermined performance of the image forming apparatus, and proceeds to Step P7, in which the transport speed of the paper feed roller pair 122 is set in advance. Predetermined speed (v1: for example, 262 mm / s
ec), the speed of the electric motor 123 (M1) is controlled to increase. As a result, the transport speed of the pair of paper feed rollers 122 is increased by a predetermined speed, and is restored to a predetermined transport performance. Then, the control means 400 proceeds to Step P8, and increases the number of times (nA) at which the speed of the electric motor 123 (M1) is increased by one.
(+1) and the process proceeds to Step P9 where the electric motor 123
It is checked whether or not the number of times (nA) at which (M1) is increased reaches a predetermined number (N). Electric motor 123 (M1)
If the number of times (nA) at which the speed is increased reaches a predetermined number (N), the control means 400 determines that the life of the sheet feeding roller pair 122 is approaching, and proceeds to step P10 to display the display means 2
70 is displayed. If the number of times (nA) at which the speed of the electric motor 123 (M1) is increased in step P9 has not reached the predetermined number (N), the process returns to step P1.

In step P6, the feed roller pair 1
As a result of comparing the transport speed (VA) of the paper feed roller 22 with the predetermined speed (VI), if the transport speed (VA) of the paper feed roller pair 122 is higher than the predetermined speed (VI), the control means 400 determines whether the paper feed roller pair 122 It is determined that the carrying capacity of the medium 122 maintains the predetermined performance, and the process proceeds to Step P11. Then, the control unit 400 executes Steps P11 to P16 to determine whether or not the conveyance capability of the registration roller pair 124 has decreased. Steps P11 to P16
Are the same as Steps S8 to S13 described above, and a description thereof will be omitted. Steps P11 to P16 are executed to compare the conveyance speed (VB) of the registration roller pair 124 with the predetermined speed (V2). As a result, the conveyance speed (VB) of the registration roller pair 124 becomes equal to the predetermined speed (V2).
2) If not, the control unit 400 determines that it is difficult to maintain the predetermined performance of the image forming apparatus, and proceeds to step P17 to set the transport speed of the registration roller pair 124 to the predetermined predetermined value. Speed (v2: for example, 134 m
m / sec), the speed of the electric motor 125 (M2) is controlled to increase. As a result, the transport speed of the pair of registration rollers 124 is increased by a predetermined speed, and is restored to a predetermined transport performance. Then, the control means 400 proceeds to Step P18, and performs the number of times (nA) of increasing the speed of the electric motor 125 (M2).
Is increased by 1 (+1), and the program proceeds to step P19, where it is checked whether the number of times (nA) at which the speed of the electric motor 125 (M2) is increased reaches a predetermined number (N). Electric motor 12
If the number of times (nA) at which the speed is increased by 5 (M2) reaches the predetermined number (N), the control means 400 sets the registration roller pair 12
It is determined that the life of the sample No. 4 is approaching, and the process proceeds to step P10 to display the result on the display unit 270. Note that step P
In step 19, if the number of times (nA) at which the speed of the electric motor 125 (M2) is increased has not reached the predetermined number (N), the process returns to step P1.

In step P16, as a result of comparing the transport speed (VB) of the registration roller pair 124 with the predetermined speed (V2), the transport speed (V
If B) is higher than the predetermined speed (V2), the control means 4
00 determines that the conveyance performance of the pair of registration rollers 124 maintains the predetermined performance, and proceeds to step P20.
Then, the control unit 400 executes Steps P20 to P25 to determine whether the conveyance capacity of the sheet reversing roller pair 216 has decreased. Steps P20 to P25 are the same as steps S14 to S19 described above, and thus description thereof will be omitted. Steps P20 to S25 are executed to execute sheet reversing roller pair 2
When the transport speed (VC) of the pair of reversing rollers 216 is lower than or equal to the predetermined speed (V3) as a result of comparing the transport speed (VC) of the image forming apparatus with the predetermined speed (V3), the control unit 400 determines whether It is determined that it is difficult to maintain the performance of the sheet reversing roller pair 216.
Is set to a predetermined speed (v3: for example,
262 mm / sec), the electric motor 215 (M
3) speed increase control. As a result, the sheet reversing roller pair 21
The transfer speed of No. 6 is increased by a predetermined speed to restore the predetermined transfer performance. Then, the control means 400 determines in step P27
, The number of times (nA) at which the speed of the electric motor 215 (M3) was increased is increased by 1 (+1), and the process proceeds to Step P28, where the number of times (nA) at which the speed of the electric motor 215 (M3) was increased (nA)
It is checked whether or not has reached a predetermined number (N). If the number of times (nA) at which the speed of the electric motor 215 (M3) is increased reaches the predetermined number (N), the control means 400 determines that the life of the sheet reversing roller pair 216 is approaching, and proceeds to step P10. It is displayed on the display means 270. As a result of comparing the transport speed (VC) of the pair of sheet reversing rollers 216 and the predetermined speed (V3) in step P25, if the transport speed (VC) of the pair of paper feed rollers 122 is higher than the predetermined speed (V3), , Control means 400 is a pair of sheet reversing rollers 2
It is determined that the transfer capability of No. 16 maintains the predetermined performance, the process returns to step S1, and the above steps S1 to S19 are repeatedly executed. In addition, step P2
If the number of times (nA) at which the speed of the electric motor 215 (M3) is increased in Step 8 does not reach the predetermined number (N), the process returns to Step P1 and repeats Steps P1 to P28.

In the illustrated embodiment described above, the transport speed (V) of the transport rollers (the pair of paper feed rollers 122, the pair of registration rollers 124, and the pair of paper reversing rollers 216) is used.
A, VB, and VC) are equal to or less than the predetermined speeds (V1, V2, and V3), the transport rollers are moved to predetermined speeds (v1, V2, V3).
v2, v3), the paper transport speed (V) detected from the respective set transport speeds of the transport rollers has been described.
A, VB, VC) may be obtained, and the speed difference may be obtained, and the speed may be increased by an amount corresponding to the speed difference, or may be displayed when the increased speed reaches a predetermined value. Further, in the illustrated embodiment described above, the determination of the decrease in the transporting ability and the subsequent countermeasures have been described with respect to the sheet feeding roller pair 122, the registration roller pair 124, and the sheet reversing roller pair 216. It goes without saying that the same can be applied.

The above description has been made based on the embodiment in which the paper conveying device of the image forming machine constructed according to the present invention is applied to a laser beam printer. However, the present invention is not limited to the embodiment, and the electrostatic copying is not limited thereto. It can be applied to various image forming machines such as a machine.

[0035]

According to the present invention, there is provided a sheet conveying device for an image forming machine, comprising: a sheet detecting sensor for detecting a sheet conveyed by a conveying roller disposed in a sheet conveying path formed through an image transfer area; The sheet passing time is calculated based on the detection signal from the sensor, and the sheet conveying speed is calculated from the sheet passing time.If the sheet conveying speed is equal to or lower than a predetermined speed, the conveying ability of the conveying roller is reduced. Control means for determining that the sheet has been transported, it is possible to reliably determine a decrease in the carrying capacity of the carrying roller. Further, according to the present invention, the fact that the transport capability of the transport roller is reduced is displayed on the display means, so that the operator knows that the transport capability of the transport roller has been reduced, and reduces the performance of the image forming machine. We can respond before it causes trouble. Further, according to the present invention, when the carrying capacity of the carrying roller is reduced,
Since the rotation speed of the electric motor that drives the transport roller is increased, the transport capability of the transport roller is restored, and the predetermined performance can be maintained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a laser beam printer as an image forming apparatus provided with a paper transport device configured according to the present invention.

FIG. 2 is a block diagram of control means for controlling the operation of the paper apparatus shown in FIG. 2;

FIG. 3 is a flowchart showing an embodiment of an operation procedure of a control unit shown in FIG. 2;

FIG. 4 is a flowchart showing another embodiment of the operation procedure of the control means shown in FIG. 2;

[Explanation of symbols]

 100: Image forming machine main body 101: Housing 104: Photoreceptor drum 106: Corona discharger for charging 108: Developing device 110: Transfer roller 112: Cleaning device 116: Laser unit 120: Paper transport path 122: Paper feed roller pair 123: Electric motor (M1) 124: Registration roller pair 125: Electric motor (M2) 126: Fixing roller pair 128: Transport roller pair 130: Branch claw 132: Discharge roller pair 134: Paper cassette 136: Sending roller 138: Separating roller pair 151 : Paper detection switch (SW1) 152: paper detection switch (SW2) 153: paper detection switch (SW3) 154: paper detection switch (SW4) 155: paper detection switch (SW5) 156: paper detection switch (SW6) 200: inversion Paper feed unit 20 : Unit housing 210: paper reversing section 212: paper reversing transport path 214: transport roller pair 215: electric motor (M3) 216: paper reversing roller pair 218: paper change guide plate 250: duplex paper feed section 252: paper transport path 254 , 256, 258: transport roller pair 260: electric motor (M4) 270: display means 400: control means

Claims (6)

[Claims] 1. A sheet conveying device for an image forming machine, comprising: a sheet conveying path formed through an image transfer area; and conveying rollers disposed on the sheet conveying path. A sheet detection sensor for detecting a sheet conveyed by the rollers, a time required for the sheet to pass based on a detection signal from the sheet detection sensor, and a sheet conveyance speed calculated from the passage time of the sheet; And control means for determining that the transporting ability of the transporting roller is reduced when the speed is equal to or lower than a predetermined speed. 2. A sheet conveying device for an image forming machine, comprising: a sheet conveying path formed through an image transfer area; and conveying rollers disposed on the sheet conveying path. A sheet detection sensor for detecting the sheet conveyed by the rollers, a display unit for indicating that the conveyance capability of the conveyance roller is reduced, and a time for the sheet to pass based on a detection signal from the sheet detection sensor. Control means for calculating the paper transport speed by means of the control means, and, when the paper transport speed is equal to or lower than a predetermined speed, displaying on the display means that the transport capacity of the transport roller is reduced. Paper transport device of an image forming machine. 3. A paper transport of an image forming machine having a paper transport path formed through an image transfer area, a transport roller disposed in the paper transport path, and an electric motor for rotating and driving the transport roller. A sheet detection sensor disposed in the sheet conveyance path and detecting a sheet conveyed by the conveyance roller; and calculating a sheet conveyance speed by obtaining a time for the sheet to pass based on a detection signal from the sheet detection sensor. And a control unit for increasing the rotation speed of the electric motor when the paper transport speed is equal to or lower than a predetermined speed. 4. The sheet conveying device of an image forming machine according to claim 3, wherein the increasing speed for increasing the rotation speed of the electric motor is a predetermined value set in advance. 5. The image forming apparatus according to claim 3, wherein the increasing speed for increasing the rotation speed of the electric motor is a value corresponding to a speed difference between a set carrying speed of the carrying roller and the paper carrying speed. Paper transport device. 6. A paper transport of an image forming machine having a paper transport path formed through an image transfer area, a transport roller disposed in the paper transport path, and an electric motor for driving the transport roller to rotate. In the apparatus, a paper detection sensor disposed on the paper conveyance path and detecting a paper conveyed by the conveyance roller, a display unit for displaying that the conveyance performance of the conveyance roller is reduced, and the paper detection sensor Control means for controlling the rotation speed of the electric motor based on the detection signal from the control unit and controlling the display means, and the control means controls the time for the sheet to pass based on the detection signal from the sheet detection sensor. To calculate the paper transport speed,
When the paper transport speed is equal to or lower than the predetermined speed, the rotation speed of the electric motor is increased, and when the number of times to increase the rotation speed of the electric motor reaches a predetermined number or when the increase speed reaches a predetermined value, the transport speed is increased. A paper transport device for an image forming machine, wherein the display means indicates that the transport capability of the roller is reduced.