JP2007076908A - Sheet conveying device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform speed control in a short time and to prevent the occurrence of step-out of a motor. <P>SOLUTION: This sheet conveying device having a plurality of rollers arranged along a conveying path of a sheet-like recording medium, and conveying the sheet-like recording medium by the rollers, comprises a temperature sensor for detecting the temperature of each roller; a computing means for acquiring variation data of the roller diameter corresponding to the temperature of each roller based on the data of the roller temperature detected by the temperature sensor, and computing the linear speed of the corresponding roller based on the acquired variation data of the roller diameter; and a control means for controlling the driving means of each roller so that the linear speed of the roller computed by the computing means is within a preset range. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet-like recording medium, a copying machine that forms an image on a sheet conveyed by the sheet conveying apparatus, a printer, a facsimile, and a digital complex machine that combines these functions. More particularly, the present invention relates to an image forming apparatus having a plurality of driven rollers such as a registration roller, a fixing roller, a photosensitive roller, and a transfer belt driving roller in a conveyance path of a sheet-like recording medium.

As this type of technology, for example, the inventions described in Patent Documents 1 to 4 are known. Among them, Patent Document 1 detects the surface temperature of the driving roller in order to control the conveying amount of the conveying belt with respect to a change in the diameter of the driving roller accompanying a change in ambient temperature and to perform accurate sub-scanning. It is described that temperature detection means and control means for controlling the conveyance amount of the conveyance belt based on the detection result by the temperature detection means are described. Similarly, in the inventions described in Patent Documents 2 to 4, the roller temperature variation is detected by detecting the roller temperature, and the value of the diameter variation is used to determine the roller linear velocity from the roller angular velocity. A technique is described in which the fluctuation is obtained, the angular speed of the roller is controlled so as to cancel the fluctuation of the linear velocity, and correction is performed so that the speed of the roller becomes constant.
JP 2004-217352 A Japanese Patent Laid-Open No. 6-043783 Patent Registration No. 3408971 JP 2000-089605 A

  In the above-described prior art, when there is a roller having a rapid temperature fluctuation, a large control is applied to the roller so that the linear velocity of the roller becomes a specific target value. As a result, the control range of the motor that drives the roller becomes large, and the motor steps out of control and becomes uncontrollable or requires a long time until it converges to the target value, causing problems in control. . In addition, since there are a plurality of rollers, if there are similar temperature fluctuations in the plurality of rollers, the control must be performed for each motor that drives the rollers. Control for each motor is performed by superimposing a plurality of motor controls, which inevitably complicates the control and takes time.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to perform speed control in a short time and prevent a motor from stepping out.

  In order to achieve the object, the first means includes a plurality of rollers arranged along a sheet recording medium conveyance path, and the sheet conveying apparatus conveys the sheet recording medium by the rollers. Temperature detection means for detecting temperature, acquisition means for acquiring fluctuation data of the roller diameter corresponding to the temperature of each roller based on detection data of the temperature of the roller by the temperature detection means, and acquisition by the acquisition means Calculating means for calculating the linear speed of the corresponding roller based on the fluctuation data of the roller diameter, and driving means for each roller so that the linear speed of the roller calculated by the calculating means is within a preset range. And a control means for controlling.

  A second means is characterized in that, in the first means, the roller includes at least two of a registration roller, a fixing roller, and a transfer belt driving roller.

  The third means is that when there is a temperature detecting means in which temperature detection is impossible in the first or second means, the control means executes the control of the linear velocity for a roller for which temperature detection is impossible. It is characterized by not.

  The fourth means is characterized in that in the third means, there is a display means for displaying when there is a roller excluded from the control of the linear velocity.

  The fifth means is characterized in that in any one of the first to fourth means, setting means for setting a range of the linear velocity of the roller is provided.

  The sixth means is characterized in that, in the fifth means, the range of the set linear velocity is a large range capable of maintaining the feeding accuracy without causing step-out.

  The seventh means is characterized in that in the fifth means, there is provided a non-volatile storage means for storing a range of the linear velocity of the roller set by the setting means.

  The eighth means is characterized in that the image forming apparatus includes a sheet conveying apparatus according to any one of the first to seventh means.

  A ninth means is the eighth means, wherein the roller includes a photosensitive roller.

  In the embodiments described later, the rollers are a registration roller 1, a photosensitive roller (photosensitive drum) 2, a fixing roller 3, a transfer belt driving roller 4, a temperature detecting unit is a temperature sensor 5, an acquiring unit, and a calculating unit. The control means corresponds to the CPU 7, the display means corresponds to the display unit 9a of the external device 9, the setting means corresponds to the external device 9, and the nonvolatile storage means corresponds to the ROM 8.

  According to the present invention, since the roller linear velocity is set within a predetermined range in accordance with the temperature change, it is possible to perform processing in a short time and to prevent the motor from stepping out.

  Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment>
FIG. 1 is a diagram showing a schematic configuration of an image forming unit of the image forming apparatus according to the first embodiment of the present invention.

  In FIG. 1, the image forming unit performs optical writing, forms a latent image of each color of KMCY, and forms a toner image with toner. The transfer belt 6 having a transfer portion disposed at a position facing the transfer belt 6, the driving roller 4 a and the driven roller group 4 b for driving the transfer belt 6, and the sheet ( A registration roller 1 for feeding a sheet-like recording medium), a fixing roller 3 for fixing a toner image transferred onto a sheet discharged from the nip between the photosensitive roller 2 and the transfer belt 6, and a roller surface. The temperature sensor 5 is mainly composed of, for example, a thermocouple. The transfer belt 6 is an endless belt that conveys a sheet on which an image is transferred on the conveyance path, and the transfer belt 6 is driven by a driving roller 4a. The fixing roller 3 includes a heating roller 3a and a pressure roller 3b for thermally fixing the toner transferred onto the transfer paper.

  FIG. 2 is a block diagram illustrating an example of a control circuit of the image forming apparatus including the image forming unit illustrated in FIG. In the figure, the control circuit includes a CPU 7, a ROM 8, and an external device 9, and the ROM 8, the external device 9 and the temperature sensor 5 are connected to the CPU 7. The CPU 7 executes predetermined control according to a program stored in the ROM 8 while using a RAM (not shown) as a work area. The temperature sensor 5 is provided to face each roller shown in FIG. The external device 9 includes a display unit that displays according to instructions from the CPU 7.

FIG. 3 shows the control in this embodiment. The temperature of each roller 1, 2, 3, 4 is detected by a temperature sensor 5 (thermocouple or the like), and each roller 1, 2 with respect to the temperature acquired as a table in advance. , 3 and 4 are used to determine the linear velocity from the angular velocity for each of the rollers 1, 2, 3 and 4. The table is stored in the ROM 8. The linear velocity V is
V = 2πR · ω / 2π = rω (1)
Where V: roller linear velocity
R: radius of roller
ω: If there is a roller that is obtained from the angular velocity of the roller and the obtained roller linear velocity V is outside the preset linear velocity range A to B (A <B), the linear velocity of the roller is Control is performed within the range of A to B. Specifically, (1) When V <A, the motor driving the roller is controlled so that V = A.

(2) When B <V, the motor driving the roller is controlled so that V = B.

By this control, the minimum linear speed control necessary for the linear speed of each roller to be in the range of A to B is performed. Therefore, the control width becomes smaller than that in the prior art, and motor step-out can be prevented.

  FIG. 3 is a flowchart showing a control procedure in the present embodiment. This control procedure is executed by the CPU 7 in accordance with the program stored in the ROM 8 as described above.

  In this processing procedure, first, detection of the temperature of each roller 1, 2, 3, 4 was started (step S1), and the temperature could be detected by the temperature sensors 5 of all the rollers 1, 2, 3, 4 In this case (step S2-YES, step S3), the linear velocity V is obtained from the angular velocity ω for all the rollers 1, 2, 3, 4 (step S4), and the linear velocity of these rollers 1, 2, 3, 4 is obtained. Control is performed so that V is within a preset range of A to B (step S5). Next, when there is a roller whose temperature could not be detected by the temperature sensor 5 due to a sensor failure or the like (step S2-NO), the temperature is obtained only for the roller that can detect the remaining temperature (step S6), and the temperature is calculated. Only for the rollers that can be detected, the linear velocity V is obtained from the angular velocity ω (step S7), and control is performed so that the linear velocity of these rollers falls within a preset range of A to B (step S8). ). That is, since the roller whose temperature could not be detected is excluded from the control target, a sensor whose temperature could not be detected due to a failure or the like can be used for control, and it is possible to prevent the control from becoming impossible or abnormal.

  In the control circuit, detection of the temperature of each roller is started, and it is detected by the CPU 7 whether or not the temperature is detected by the temperature sensors 5 of all the rollers, and at least the temperature sensors of the rollers 1, 2, 3, 4 are detected. If the temperature could not be detected by one of 5, a message to that effect is displayed on the display unit of the external device 9 to notify the user or a service person performing maintenance. Accordingly, the user or a service person who performs maintenance can know the fact by the external device 9, and further can identify the temperature sensor that could not be detected. For example, it is possible to quickly deal with a failed sensor.

  Further, as an initial state of the image forming apparatus, initial values are set in the ranges A to B of the linear velocity V used for control, but the occurrence rate of step-out varies depending on individual motors. Then, the values of A to B are reset. Specifically, a user or a service person who performs maintenance sets arbitrary values A to B in the image forming apparatus by the external device 9. When the image forming apparatus executes the control procedure shown in FIG. 3, control is performed with reference to the reset values A to B. As a result, optimal control can be performed for each image forming apparatus. Further, the arbitrary values A to B reset as described above are stored in the ROM 8 which is a nonvolatile memory. The CPU 7 performs control with reference to the values A to B stored in the ROM 8 when executing the processes of steps S5 and S8. As a result, even after the image forming apparatus is turned off, the values A to B set from the external device 9 by the user or a serviceman who performs maintenance are held, so the power is turned on again. Even when the image forming apparatus is used, control can be performed with reference to the set values A to B. As a result, it is not necessary to reset the values A to B every time the power is turned on, and the workload of the user or service person is reduced.

<Second Embodiment>
FIG. 4 is an example of an image forming apparatus according to the second embodiment, and is a schematic configuration diagram showing an example of a digital copying machine in which the control is executed. In the figure, a digital copying machine is for monochrome image formation. A main body 400, an image reading device 500 installed on the upper portion of the image forming apparatus main body 400, and an automatic document feeder (hereinafter referred to as an automatic document feeder) mounted thereon. , “ADF”) 550, a large-capacity paper feeding device 700 disposed on the right side of the image forming apparatus main body 400 in the same figure, and a sheet post-processing device disposed on the left side of the image forming apparatus main body 400 in the same figure. 800 is basically composed.

  The image forming apparatus main body 400 includes an image writing unit 410, an image forming unit 420, a fixing unit 430, a duplex conveying unit 440, a paper feeding unit 450, a vertical conveying unit 460, and a manual feeding unit 470.

  The image writing unit 410 modulates the LD, which is a light source, based on the image information of the document read by the image reading device 500, and writes laser on the photosensitive drum 421 by a scanning optical system such as a polygon mirror and an fθ lens. is there. The image forming unit 420 includes a photosensitive drum 421 and known electrophotographic imaging elements such as a developing unit 422, a transfer unit 423, a cleaning unit 424, and a charge eliminating unit provided along the outer periphery of the photosensitive drum 421. Consists of.

  The fixing unit 430 fixes the image transferred by the transfer unit 423 on the transfer paper. The double-sided conveyance unit 440 is provided downstream of the fixing unit 420 in the transfer sheet conveyance direction, and includes a first switching claw 441 that switches the transfer sheet conveyance direction to the sheet post-processing device 800 side or the double-side conveyance unit 440 side, , The reverse conveying path 442 guided by the switching claw 441, the image forming side conveying path 443 that conveys the transfer paper reversed by the reverse conveying path 442 to the transfer unit 423 again, and the reverse transfer paper after the sheet post-processing device 800. A second switching claw 445 is disposed at a branch portion between the image forming side conveying path 443 and the post processing side conveying path 444.

  The sheet feeding unit 450 includes four sheet feeding stages, and the transfer sheets stored in the sheet feeding stages selected by the pickup roller and the sheet feeding roller are drawn out and guided to the vertical conveyance unit 460. The vertical conveyance unit 460 conveys the transfer paper fed from each paper feed stage to the registration roller 461 immediately upstream in the paper conveyance direction of the transfer unit 423, and the registration roller 461 provides a visible image on the photosensitive drum 421. The transfer paper is fed into the transfer unit 423 in time with the leading edge. The manual feed portion 470 includes an openable and closable manual feed tray 471, and opens the manual feed tray 471 as needed to supply transfer paper manually. Also in this case, the transfer timing of the transfer paper is taken by the registration roller 461 and is transported.

  The large-capacity paper feeding device 700 supplies a large amount of transfer paper of the same size, and the bottom plate 702 rises as the transfer paper is consumed, so that the paper can always be picked up from the pickup roller 701. ing. The transfer paper fed from the pickup roller 701 is conveyed from the vertical conveyance unit 460 to the nip of the registration roller 461.

  The sheet post-processing apparatus 800 performs predetermined processing such as punching, alignment, stapling, and sorting. In this embodiment, the punch 801, the staple tray (alignment) 802, the stapler 803, and the shift tray 804 are used for the above functions. I have. In other words, the transfer paper carried from the image forming apparatus 400 to the paper post-processing apparatus 800 is punched one by one with the punch 801 when punching, and then if there is no particular processing, the proofing is performed. When sorting, stacking, and sorting to the tray 805, the sheets are discharged to the shift tray 804, respectively. In this embodiment, the sorting is performed by the reciprocating movement of the shift tray 804 by a predetermined amount in a direction orthogonal to the sheet conveyance direction. In addition, sorting can be performed by moving the paper in a direction orthogonal to the paper transport direction on the paper transport path.

  In the case of alignment, the transfer paper that has been punched or not punched is guided to the lower transport path 806, and the staple tray 804 is aligned in the direction perpendicular to the paper transport direction by the rear end fence. In the jogger fence, alignment in the direction parallel to the paper transport direction is performed. Here, when binding is performed, a predetermined position of the aligned sheet bundle, for example, a predetermined position such as a corner portion or two central positions is bound by the stapler 803 and discharged to the shift tray 804 by the discharge belt. In this embodiment, a pre-stack conveyance path 807 is provided in the lower conveyance path 806, and a plurality of sheets are stacked at the time of conveyance to avoid interruption of the image forming operation on the image forming apparatus main body 400 side during post-processing. Be able to.

  The image reading apparatus 500 is guided onto the contact glass 510 by the ADF 600, optically scans the stopped original, and reads the image formed by the imaging lens through the first to third mirrors, such as a CCD or CMOS. Read by the photoelectric conversion element. The read image data is subjected to predetermined image processing by an image processing circuit (not shown) and temporarily stored in a storage device. Then, it is read from the storage device by the image writing unit 410 during image formation, modulated according to the image data, and optical writing is performed.

  The ADF 550 has a double-sided reading function, and is attached to the contact glass 510 installation surface of the image reading device 500 so as to be freely opened and closed. In the ADF 550, the document placed on the document placement table 551 is automatically sent onto the contact glass 510 when the document is read.

  Also in this example, the same control is performed for driving the registration roller 461, the photoconductive drum 421, the driving roller for driving the transfer belt of the transfer unit 423, the manual attaching roller of the fixing unit 430, and the pressure roller.

  In the first embodiment, it is referred to as the photoconductor roller 2 and in the first embodiment, it is referred to as the photoconductor drum 421. However, all of them are located in a paper transport path and have a cylindrical shape or a paper transport function. Although it has a cylindrical shape and is generically called a roller as a function in the claims, it is substantially equivalent.

  As described above, according to the first and second embodiments, when there is a roller having a sudden temperature fluctuation, a large control is performed on the roller so that the linear velocity of the roller becomes a specific target value. However, since the control is performed so that the linear speed of the roller is within a range of the linear speed having a certain width, it is not necessary to perform a large control as in the prior art. As a result, the motor that drives the roller can be prevented from stepping out.

1 is a diagram illustrating a schematic configuration of an image forming unit of a tandem image forming apparatus according to an embodiment of the present invention. 1 is a block diagram illustrating a schematic configuration of a control circuit of an image forming apparatus according to an embodiment of the present invention. It is a flowchart which shows the control procedure performed with CPU of FIG. It is a figure which shows the system configuration | structure of the monochrome image forming apparatus which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Registration roller 2 Photosensitive roller 3 Fixing roller 4 Transfer belt drive roller 5 Temperature sensor 6 Transfer belt 7 CPU
8 ROM
9 External device 9a Display unit 421 Photosensitive drum

Claims (9)

In the sheet conveying apparatus in which a plurality of rollers are arranged along the conveying path of the sheet-like recording medium, and the sheet-like recording medium is conveyed by the rollers,
Temperature detecting means for detecting the temperature of each roller;
Acquisition means for acquiring fluctuation data of the roller diameter corresponding to the temperature of each roller based on the temperature detection data of the roller by the temperature detection means;
Calculation means for calculating the linear velocity of the corresponding roller based on the fluctuation data of the roller diameter acquired by the acquisition means;
Control means for controlling the driving means of each roller so that the linear velocity of the rollers calculated by the calculating means falls within a preset range;
A sheet conveying apparatus comprising:   The sheet conveying apparatus according to claim 1, wherein the roller includes at least two of a registration roller, a fixing roller, and a transfer belt driving roller.   3. The sheet conveying apparatus according to claim 1, wherein when there is a temperature detecting unit that cannot detect the temperature, the control unit excludes the roller that cannot detect the temperature from the control target. 4.   4. A sheet conveying apparatus according to claim 3, further comprising display means for displaying when there is a roller excluded from the control of the linear velocity.   The sheet conveying apparatus according to claim 1, further comprising a setting unit that sets a range of the linear velocity of the roller.   6. The sheet conveying apparatus according to claim 5, wherein the set linear velocity range is a large range capable of maintaining feeding accuracy without causing step-out.   6. The sheet conveying apparatus according to claim 5, further comprising a non-volatile storage unit that stores a range of the linear velocity of the roller set by the setting unit.   An image forming apparatus comprising the sheet conveying device according to claim 1.   8. The image forming apparatus according to claim 7, wherein the roller includes a photosensitive roller.

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