JP6358477B2 - Paper feed roll holding device, image forming apparatus, and printing control method - Google Patents

Description

  The present invention relates to a paper feed roll holding device, an image forming apparatus, and a printing control method.

  Conventionally, in an electrophotographic image forming apparatus, a photosensitive drum of a developing device is uniformly charged and initialized, a latent image is formed on the photosensitive drum by optical writing, and the latent image is converted into a toner image (development). Then, the toner image is secondarily transferred to the printing medium and fixed by a fixing device.

  In the above image forming apparatus, when a long paper wound in a roll shape is used as a printing medium, the end of the long paper is usually fastened to the paper tube with a tape or the like, and when the paper is pulled out to the end, it is natural from the paper tube. It is a mechanism to peel off. However, when the long paper is firmly fixed to the paper tube, the end of the long paper is not peeled off from the paper tube, so that the transport driving operation is continued even though the paper feed is stopped. This affects the image being printed and also damages the drive system, causing failure.

  In order to avoid this, it is necessary to detect the end of the long paper, but in the paper trailing edge detection using a general optical sensor, as described above, when the paper does not peel from the paper tube, The end of the long paper cannot be detected at all.

  Therefore, as disclosed in Patent Document 1, a mechanical contact switch or the like detects that the bearing portion of the paper tube is displaced in the pulling direction by pulling the paper that does not peel off, or the bearing moves as in Patent Document 2. A method has been proposed in which a mechanical contact switch is used to detect the forced movement of the bearing in the same manner.

  As another method, a method for detecting a difference in an optical sensor on the premise that the outer surface of the paper tube is darker than the long paper as in Patent Document 3 has been proposed.

  Similarly, as a method of using the optical sensor, as in Patent Document 4, when the long paper is not pulled out to the end, the pulling direction is a tangential direction with respect to the outer peripheral surface, and the paper is unloaded to the end. In particular, focusing on the difference that the pull-out direction is the direction connecting the center of the paper tube and the first transport roller that receives the paper at the shortest distance, a method of detecting the difference in reflected light by this difference with an optical sensor has been proposed. ing.

  On the other hand, as a method of reliably detecting at high speed without relying on mechanical or optical detection, as in Patent Document 5, the shaft of the long paper is configured with a clutch mechanism and a drive circuit having a torque limiter function, There has been proposed a method for detecting the end of the long paper that does not peel off the paper tube by detecting the change in the rotational speed (the number of revolutions per unit time) of the drive motor and the change in the current supplied to the motor.

JP 2000-109256 A JP-A-10-236723 Japanese Patent Laid-Open No. 08-127167 JP 2014-104670 A JP 2012-193032 A

  However, the methods of Patent Documents 1 and 2 require mechanical machining accuracy to detect the displacement or movement of the bearing, or detect the change of the physical bearing, so that the detection speed becomes slow. There was already a problem of damaging when detected.

  Further, in the method of Patent Document 3, mechanical processing accuracy is not so much required and the detection speed is fast, but the reflectance of the surface of the long paper and the paper tube is originally varied, and it is used for all long papers. This is not possible, and complicated adjustment is required, and an optical sensor that realizes the adjustment is required, leading to an increase in cost.

  In the case of Patent Document 4, since it depends on variations in reflected light, complicated adjustments are also required, and an optical sensor for realizing the adjustment is required, leading to an increase in cost.

  The method of Patent Document 5 also has a problem that although it can be reliably detected at high speed, a drive circuit and a device are required, leading to an increase in cost.

  SUMMARY OF THE INVENTION An object of the present invention is to reliably detect the end of a printing medium wound in a roll shape, and to protect the printing apparatus and its printed product as much as possible.

The paper feed roll holding device according to the present invention comprises a detecting means for detecting an angular velocity of the paper feed roll when the print medium is pulled out from the paper feed roll wound around the winding core in a roll shape, Based on the change in the angular velocity of the paper feed roll detected by the detection means, the derivation means for deriving the angular acceleration of the paper feed roll, and on the basis of the angular acceleration of the paper feed roll derived by the derivation means Determining means for determining a connection state between the end of the printing medium and the winding core; and when the determining means determines that the end of the printing medium is connected to the winding core, Braking means that weakens the braking of the rotation of the paper feeding roll rather than braking the rotation of the paper feeding roll when the medium is unwound from the tangential direction of the outer peripheral surface of the paper feeding roll. The And butterflies.

An image forming apparatus according to the present invention is an image forming apparatus including a paper feed roll holding device that holds a paper feed roll in which a printing medium is wound around a winding core. The paper feed roll holding device includes: Detecting means for detecting an angular speed of the paper feed roll when the printing medium is pulled out while rotating the winding core from the paper feed roll as an axis; and an angular speed of the paper feed roll detected by the detection means. Deriving means for deriving the angular acceleration of the paper feed roll based on the change, and coupling of the end of the printing medium and the winding core based on the angular acceleration of the paper feed roll derived by the deriving means When the judging means judges the state and the judging means judges that the end of the printing medium is coupled to the winding core, the drawing direction of the printing medium is on the outer peripheral surface of the winding core. And a cutting means for cutting the printing medium before the before the vertical by the determination unit, when the angular acceleration of the feed roll becomes smaller than a predetermined second threshold value, the object When the end of the print medium is determined to be uncoupled from the winding core, and the image forming apparatus determines that the end of the print medium is coupled to the winding core, When printing is continued until the cutting end of the print medium based on the timing of cutting by the cutting means, and the determination means determines that the end of the print medium is not coupled to the winding core, Printing is continued until the end of the printing medium based on the timing .

The printing control method according to the present invention is a printing control for controlling printing on the printing medium in which the printing medium is pulled out at a predetermined speed from a paper feed roll in which the printing medium is wound around a winding core. A step of detecting an angular velocity of the paper feed roll when the printing medium is pulled out from the paper feed roll while rotating about the winding core; and a method of detecting the detected angular velocity of the paper feed roll. Deriving the angular acceleration of the paper feed roll based on the change, and determining the coupling state between the end of the printing medium and the winding core based on the derived angular acceleration of the paper feed roll. a step, when said end of the printing medium is determined to be coupled to the winding core, the paper when the printing medium is unwound from a tangential direction of the outer peripheral surface of the feed roll Than to brake the rotation of the roll, characterized in that it comprises the steps of: weakening the braking of the rotation of the sheet feeding roll.

  According to the present invention, it is possible to reliably detect the end of the printing medium wound in a roll shape, and to protect the printing apparatus and the printed product as much as possible.

1 is an overall conceptual diagram of an image forming apparatus 10 for printing on long paper (a printing medium) according to an embodiment of the present invention. FIG. 3 is a conceptual diagram illustrating a configuration of an unwinder 25 of the image forming apparatus 10 according to the present embodiment. In the image forming apparatus 10 according to the present embodiment, normally, the end of the long paper 16a is slightly attached to the paper tube 60, and the end of the long paper 16a is firmly attached to the paper tube 60. 6 is a conceptual diagram showing a change in the rotation speed of each paper feed roll 16 when the paper is being fed. In the image forming apparatus 10 according to the present embodiment, when the sticking of the long paper 16a to the paper tube 60 is strong, it is a conceptual diagram for explaining the change in the rotation speed of the paper feed roll 16. FIG. In the image forming apparatus 10 according to the present embodiment, it corresponds to the elapsed time from the time when the sticking point of the long paper 16a to the paper tube 60 exceeds the contact point B which is the drawing position of the printing medium and the rotation speed of the paper tube 60. It is a conceptual diagram which shows an example of the change of the pulse period of the encoder to perform. 2 is a block diagram illustrating a partial configuration of a control system of the image forming apparatus 10 according to the present embodiment. FIG. 6 is a flowchart for explaining the operation (sheet end detection processing) of the image forming apparatus 10 according to the present embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A. Configuration of Embodiment FIG. 1 is an overall conceptual diagram of an image forming apparatus 10 for printing on long paper (a printing medium) according to an embodiment of the present invention. In FIG. 1, the image forming apparatus 10 includes a long paper feeding unit 15, a printer main body (image forming unit) 30, and a long paper winding unit 50. The long paper feeding unit 15 is installed at the lower part of the printer main body 30, and a paper feeding roll 16 fitted to the unwinder shaft 20 is installed. More specifically, the paper feed roll 16 is composed of a long paper (medium to be printed) 16 a wound around a paper tube (winding core), and the paper tube (winding core) is fitted to the unwinder shaft 20. As a result, it is installed in the long paper feeding unit 15. The paper feed roll 16 is held rotatably about the unwinder shaft 20 as a rotation axis. The unwinder shaft 20 is not provided with a driving means (such as a motor), and rotates when the long paper 16 a is pulled out from the paper supply roll 16 by the transport roller in the printer main body 30. The powder brake 28 brakes the rotation of the paper feed roll 16 via the unwinder shaft 20 when it rotates when the long paper 16 a is pulled out from the paper feed roll 16. The paper guide roller 17 changes the conveyance direction of the long paper (recording medium) 16 a pulled out from the paper supply roll 16 and guides it to be conveyed toward the upper printer body 30.

  The edge sensor 18 is disposed between the paper guide roller 17 and a paper guide roller 19 described later, and positions of both ends in the paper width direction perpendicular to the conveying direction of the long paper 16a unwound from the paper supply roll 16 are detected. To detect. Although one end sensor 18 is shown in FIG. 1, it is disposed at each end of the long paper 16a. The edge sensor 18 detects the skew of the long paper 16a from the positions of both ends of the detected long paper 16a in the paper width direction.

  The paper guide roller 19 changes the transport direction of the long paper 16 a that has passed through the end sensor 18 and guides the transport to the upper printer body 30. The lower paper transport roller pair 21 and the upper paper transport roller pair 23 sandwich the long paper 16a fed from the paper feed roll 16 from both sides and transport it toward the upper printer body 30. Further, each of the lower paper transport roller pair 21 and the upper paper transport roller pair 23 includes a clutch mechanism in at least one of the pair. When the clutch mechanism is turned on, the driving force of the rotating shaft is transmitted to the roller, and when it is turned off, the driving force from the rotating shaft is cut off and driven.

  At the start of printing, when the long paper 16a is transported into the printer main body 30 and is sandwiched between transport rollers (such as a main body entrance transport roller 47 described later) in the printer main body 30, the lower paper transport roller pair 21 and the upper paper The clutch mechanism of the sheet conveying roller pair 23 is turned off (the clutch is disengaged). After the clutch mechanism of the lower paper transport roller pair 21 and the upper paper transport roller pair 23 is turned off, the long paper 16a is transported by a transport roller (such as a main body entrance transport roller 47 described later) in the printer main body 30. The The lower paper transport roller pair 21 and the upper paper transport roller pair 23 are driven by the transported long paper 16a.

  The auto cutter 22 cuts the long paper 16a when the paper feed roll 16 is installed for the first time to feed the long paper 16a or when printing is completed. The paper passage sensor 24 detects the passage of the leading edge or the trailing edge of the long paper 16a conveyed to the printer main body 30.

  The printer main body 30 is an electrophotographic tandem color image forming apparatus of an intermediate transfer system, and includes a drum / developing device 31, a transfer belt device 32, a toner cartridge 33, an electrical unit 34, a paper feeding unit 35, and a fixing device. 36 or the like.

  A toner cartridge 33 is disposed above the transfer belt device 32, and a drum / developing device 31 is disposed substantially immediately below the transfer belt device 32. The transfer belt device 32 includes an intermediate transfer belt 37, a driving roller 38, and a driven roller 39. The drum / developing device 31 is configured by contacting four lower developing devices 31k, 31c, 31m, and 31y in a multi-stage manner in contact with the lower running surface of the intermediate transfer belt 37 of the transfer belt device 32 from the right to the left in FIG. Is done.

  The developing devices 31k, 31c, 31m, and 31y include four toner cartridges 33, and black (K), cyan (C), magenta (M), and yellow (Y) indicated by K, C, M, and Y in FIG. ) Toner is supplied.

  The toner cartridge 33 is composed of four toner cartridges arranged above the upper running surface of the intermediate transfer belt 37. The four toner cartridges 33 contain black (K), cyan (C), magenta (M), and yellow (Y) supply toners, respectively. A toner vertical conveyance path 40 is disposed between the toner cartridge 33 and the drum / developing device 31, and a predetermined amount of toner is conveyed from the toner cartridge 33 into the drum / developing device 31.

  The developing device 31 includes four developing devices 31k, 31c, 31m, and 31y arranged in a multistage manner. Each of the developing devices 31k, 31c, 31m, and 31y has the same configuration except for the color of the toner that develops the image. Of the developing devices 31k, 31c, 31m, and 31y, the three upstream developing devices 31c, 31m, and 31y are cyan (C), magenta (M), and yellow (subtractive three primary colors), respectively. A color image of Y) color toner is formed on the intermediate transfer belt 37, and the developing device 31k generates a monochrome image of black (K) color toner mainly used for dark portions of characters and images on the intermediate transfer belt 37. To form.

  The transfer belt device 32 has an endless intermediate transfer belt 37 that extends in the shape of a flat loop in the left-right direction in the figure at the approximate center of the printer main body 30, and the intermediate transfer belt 37 is stretched over the intermediate transfer belt 37. A driving roller 38 and a driven roller 39 are provided to circulate and move the transfer belt 37 counterclockwise in the drawing.

  The transfer belt device 32 further includes a secondary transfer backup roller 41 over which an intermediate transfer belt 37 is stretched above the drive roller 38. A secondary transfer roller 42 is pressed against the secondary transfer backup roller 41 via an intermediate transfer belt 37.

  The long paper 16 a is pressed against the intermediate transfer belt 37 when being transported between the secondary transfer backup roller 41 and the secondary transfer roller 42. As a result, on the long paper 16a, a color image formed with the cyan (C), magenta (M), and yellow (Y) color toner and a monochrome image formed with the black (K) toner formed on the intermediate transfer belt 37 are formed. The images are sequentially transferred and supplied to the fixing device 36.

  The fixing device 36 is a belt-type heat fixing device, and fixes the toner image transferred to the long paper 16a. The long paper 16 a carried out from the fixing device 36 is taken up by a take-up roll 51 installed in a long paper take-up unit (rewinder) 50 via a face-up unit 45. The printer main body 30 can also feed and print a cut sheet (cut sheet) from the sheet feeding unit 35. Further, since the fixing device 36 has the strongest clamping force for clamping the long paper 16a in the printer main body 30, the conveyance speed in the fixing device 36 determines the overall conveyance speed of the long paper 16a. The fixing device 36 has a sufficient clamping force when printing cut paper (cut sheet paper) that is not wound.

  FIG. 2 is a conceptual diagram showing the configuration of the unwinder 25 of the image forming apparatus 10 according to the present embodiment. 3A to 3C show the normal state, the end of the long paper 16a slightly attached to the paper tube 60, and the long paper in the image forming apparatus 10 according to the present embodiment. FIG. 11 is a conceptual diagram showing changes in the rotation speed of each paper feed roll 16 when the end of 16a is firmly attached to the paper tube 60.

The shaft 61 on which the paper tube 60 of the paper feed roll 16 is mounted is provided with a rotating plate 63 coaxially with the shaft 61 and having a plurality of slits 62 formed in a circular shape at equal intervals. In addition, the slit 62 is a schematic diagram with a small number of slits for easy understanding. The long paper 16a is drawn from the paper feed roll 16 at a constant linear velocity V (mm / s) by the lower paper transport roller pair 21 or the upper paper transport roller pair 23 shown in FIG. Rotates at a rotational speed (angular speed ω) corresponding to the radius r. That is, as the long paper 16a is pulled out from the paper feed roll 16, and the radius r changes from large to small (according to the elapsed time), the rotation of the paper feed roll 16, that is, the shaft 61 and the rotating plate 63 is rotated. Speed (angular speed ω) increases.
A powder brake 28 is installed on the unwinder shaft 20 to which the paper feed roll 16 is fitted. The powder brake 28 controls the cohesive force of the magnetic material according to the control current from the control unit 341, applies a predetermined brake to the rotation of the paper feed roll 16, and controls the load tension of the paper.

  The slit encoder 64 is fixed in the vicinity of the rotating plate 63, detects the passage of the slit 62 on the rotating plate 63 that rotates with the rotation of the shaft 61, and detects the rotational speed of the shaft 61, that is, the feeding roll 16. A pulse signal having a period corresponding to the rotational speed (angular speed ω) is output to the control unit 341 described later.

  Normally, there is a remaining amount of the long paper 16a wound around the paper supply roll 16, and the tangent contact point B connecting the roll surface and the paper guide roller 17 (drawing position of the printing medium = As long as the long paper 16a to be drawn is separated from the paper feed roll 16), the long paper 16a is drawn at a constant linear velocity (Vmm / s). As shown in FIG. 3A, the speed gradually increases according to the radius r (elapsed time) of the paper feed roll 16, and there is no sudden change.

  When the end of the long paper 16a reaches the contact B and the sticking to the paper tube 60 is not strong, the end of the long paper 16a is naturally peeled off from the paper tube 60 at the contact B and is drawn out. The rotational force due to the paper 16a is lost. For this reason, the shaft 61 on which the paper tube 60 of the paper feed roll 16 is mounted does not stop immediately due to the inertial force, and the powder brake 28 applies a predetermined braking as shown in FIG. 3B. Therefore, the rotation speed is stopped while decelerating. Further, the end position of the long paper 16a can be detected from the change in the rotational speed.

  On the other hand, when the long paper 16a is firmly attached to the paper tube 60, the long paper 16a is not peeled off from the paper tube 60 even if the end of the long paper 16a reaches the contact point B. The paper roll 16 continues to rotate until the contact point of the long paper 16 a reaches the contact point P on the shortest distance connecting the shaft 61 and the paper guide roller 17. In this case, the rotation speed of the shaft 61 on which the paper tube 60 of the paper feed roll 16 is mounted, as shown in FIG. To do.

  Here, a change in the rotation speed of the paper feed roll 16 when the long paper 16a is firmly attached to the paper tube will be described in detail.

  FIG. 4 is a conceptual diagram for explaining the change in the rotation speed of the paper feed roll 16 when the long paper 16a is firmly attached to the paper tube 60 in the image forming apparatus 10 according to the present embodiment. FIG. 5 shows the elapsed time from the time when the attachment point of the long paper 16a to the paper tube 60 exceeds the contact point B which is the drawing position of the print medium and the paper tube in the image forming apparatus 10 according to the present embodiment. It is a conceptual diagram which shows an example of the change of the pulse period of the encoder corresponding to 60 rotational speed.

  In the triangle PnAC, the following equation (1) is obtained.

  In the isosceles triangle ABPn,

It becomes.
Substituting Equations (2) and (3) into Equation (1) yields Equation (4) below.

  From the three stroke function formulas (5) and (6), the formula (4) becomes the following formula (7).

Here, if the end of the long paper 16a is attached firmly to paper tube 60, when the gluing point P ₀ of the end of the long paper 16a is moved from the contact B to Pn (i.e., only the θn rotation when), the distance to the paper guide rollers 17, the Ln of _{L 0.} Therefore, the elapsed time tn (s) during this period can be expressed by the following equation (8), where the linear velocity of the long paper 16a is V (mm / s).

  Substituting Equation (7) into Equation (8) above yields Equation (9).

Here, using the linear velocity V = 181.6 mm / s, L ₀ = 300 mm, and r = 43 mm, the time for changing from θn = 44 ° to 45 ° is derived from Equation (9).
θn = 44 ° tn = 0.163 s
θn + 1 = 45 ° tn + 1 = 0.16581s
It becomes. Accordingly, the angular velocity ωn at this time is expressed by the following equation (10).

  On the other hand, the angular velocity during normal rotation is expressed by the following equation (11) under the same conditions.

Therefore, the ωn> ω _0.
That is, the rotation speed of the paper tube 60 from the gluing point P ₀ of the end of the long paper 16a is beyond the contact B (sheet feed roller 16) is made can be seen faster than the normal rotation.

  From the above formulas (9) and (10), the change in the rotational speed of the paper tube 60 after the contact B is exceeded is as shown in FIG. In FIG. 5, the vertical axis indicates the pulse period (ms) output by the slit encoder 64, and the horizontal axis indicates the elapsed time (s). The pulse period represents a value corresponding to the rotation speed of the paper feed roll 16, and a shorter pulse period indicates a higher rotation speed, and a longer pulse period indicates a lower rotation speed.

  As described above, when the end of the long paper 16a is firmly fixed to the paper tube 60 and does not peel off even when the end exceeds the contact B, the rotation speed of the paper feed roll 16 (that is, the paper tube 60) is abrupt. After it gets faster, it will stop. In other words, the rate of change of the rotational speed (angular velocity ω) of the paper feed roll 16, that is, the angular acceleration, becomes larger than normal. At this time, the angular acceleration suddenly increases, which is different from the mechanism when the long paper 16 a is unwound from the tangential direction of the outer peripheral surface of the paper feed roll 16. Due to this increase in angular acceleration and the moment of inertia of the paper feed roll 16 (that is, the paper tube 60) and the unwinder shaft 20, the load tension of the long paper 16a also increases, so that the braking force of the powder brake 28 is increased. This is weaker than when the long paper 16 a is unwound from the tangential direction of the outer peripheral surface of the paper feed roll 16.

In the present invention, the rotational speed (angular speed ω) of the paper feed roll 16 is detected, and the long paper 16a and the paper tube 60 are pasted based on the angular acceleration of the paper feed roll 16 derived from the change in the rotational speed. Judging state (combined state) is determined. That is, when the angular acceleration of the paper feed roll 16 becomes smaller than a predetermined negative value, the rotational speed (angular speed ω) of the paper feed roll 16 has suddenly decreased, that is, it has been slightly pasted. It is determined that the end of the paper 16a has been peeled off from the paper tube 60, and the end position of the long paper 16a is detected. In this case, when the glue point P _{0 at} the end of the long paper 16 a exceeds the contact point B, the end of the long paper 16 a is naturally peeled from the paper tube 60. Therefore, in this case, the image generation and the conveyance of the long paper 16a are continued until printing of the detected end of the long paper 16a is completed, and the image ahead of the end of the long paper 16a is the toner. Since this is wasted, image generation is suppressed.

  On the other hand, when the angular acceleration of the paper feed roll 16 becomes larger than a predetermined positive value, the rotational speed (angular speed ω) of the paper feed roll 16 suddenly increases, that is, the end of the long paper 16a becomes firm. It is determined that the paper tube 60 is attached (combined). If it is determined that the end of the long paper 16a is firmly attached to the paper tube 60 and does not peel off naturally from the paper tube 60, the braking force of the powder brake 28 is immediately increased to increase the angular velocity of the paper feed roll 16. 1 is operated to cut the long paper 16a by operating the auto cutter 22 shown in FIG. 1, thereby avoiding the forced stop of the paper conveyance and reducing the influence on the printed product and the damage to the driving device. ing. Therefore, in this case, the conveyance of the long paper 16a is continued until the printing of the cut end portion of the cut long paper 16a is completed, and the toner beyond the cut end portion is wasted. Suppresses image generation.

  Note that even if the conveyance drive is stopped without operating the auto cutter 22, there is an effect of reducing damage to the driving device. However, an image being printed is wasted, and actually, the conveyance drive is not performed. Since the sudden stop causes a considerable damage to the driving device, it is preferable to cut the long paper 16a by the auto cutter 22 as described above.

FIG. 6 is a block diagram illustrating a partial configuration of the control system (electrical unit 34) of the image forming apparatus 10 according to the present embodiment. It should be noted that portions corresponding to those in FIG.
In FIG. 3, the electrical unit 34 includes a control unit 341 and an auto cutter driving unit 342.

  The control unit 341 detects the rising edge of the pulse signal from the output signal from the slit encoder 64, derives the pulse period from between the rising edges, and uses 100 points including the current pulse period, and the moving average value of the pulse period Is derived. The smaller the moving average value of the pulse period, the faster the current rotation speed of the paper feed roll 16.

  Based on the difference ratio between the moving average value of the previous pulse period and the moving average value of the current pulse period, the control unit 341 determines whether or not the end of the current long paper 16a has been reached, that is, still winding. It is a normal time when there is a remaining amount, a case where the end of the long paper 16a is peeled off naturally, or a case where the end of the long paper 16a is firmly attached to the paper tube 60 and does not peel off. And the continuation of image generation and printing is controlled according to the determination result. The details of the difference ratio will be described later.

  When the control unit 341 determines that it is a normal time when the long paper 16a is pulled out from the paper supply roll 16, it detects the rising edge from the slit encoder 64, derives the pulse period, and moves the current pulse period. The derivation of the average value and the determination of the current end state of the paper feed roll 16 based on the difference ratio between the moving average value of the previous pulse period and the moving average value of the current pulse period are continued.

  In addition, when the control unit 341 determines that the end of the long paper 16a is naturally peeled off from the paper tube 60, the control unit 341 continues to the end of the long paper 16a where the conveyance of the long paper 16a is detected. Further, when the control unit 341 determines that the end of the long paper 16a is not peeled off while being firmly attached to the paper tube 60, the control force of the powder brake 28 is increased according to the increase in angular velocity (angular acceleration). Then, the auto cutter driving unit 342 is driven to cut the long paper 16a, and the conveyance is continued to the end of the cut long paper 16a.

  That is, the auto cutter driving unit 342 drives the auto cutter 22 according to an instruction from the control unit 341 and cuts the long paper 16a. As described above, when it is detected that the end of the long paper 16a is not peeled off while being firmly attached to the paper tube 60, the braking force of the powder brake 28 is immediately increased to the angular velocity (angular acceleration). Accordingly, by weakening and cutting the long paper 16a, it is possible to avoid forcibly stopping the paper conveyance and reduce damage to the printed product and the driving device during printing.

  FIG. 7 is a flowchart for explaining the end portion determination operation of the long paper 16a in the image forming apparatus 10 according to the present embodiment.

  The control unit 341 determines whether a rising edge is detected from the output signal from the slit encoder 64 (step S10). If the rising edge is not detected (NO in step S10), the control unit 341 determines whether or not twice or more of the moving average value of the current pulse period has elapsed (step S12). Then, when more than twice the moving average value of the current pulse period has not elapsed (NO in step S12), the control unit 341 returns to step S10 and repeats the above determination.

  On the other hand, if the rising edge is not detected even when the moving average value of the pulse period is twice or more (YES in step S12), the control unit 341 determines that the paper feed roll 16 is stopped and performs the process as it is. finish.

  If a rising edge is detected before the moving average value of the pulse period is twice or more (YES in step S10), the control unit 341 determines that the paper feed roll 16 is rotating, A pulse period is derived from the time difference between the previous rising edge and the current rising edge (step S14). Next, the control unit 341 derives a moving average value at 100 points in the past pulse period including the derived pulse period (step S16).

  The control unit 341 calculates the difference ratio between the moving average value of the previous pulse cycle and the moving average value of the current pulse cycle ({(moving average value of the current pulse cycle−moving average value of the previous pulse cycle) / previous pulse cycle). It is determined how much is the moving average value of the pulse period} × 100) (step S18).

  The difference ratio is a value corresponding to the rate of change of the rotational speed (angular velocity) of the paper feed roll 16, that is, a value corresponding to the angular acceleration of the paper feed roll 16. When the difference ratio is a positive value, it indicates that the angular velocity of the paper feed roll 16 is decelerating, and the value indicates the magnitude of change in angular velocity, that is, the magnitude of angular acceleration of the paper feed roll 16. On the other hand, when the difference ratio is a negative value, it indicates that the angular velocity of the paper feed roll 16 is accelerating, and the value indicates the magnitude of change in angular velocity, that is, the magnitude of angular acceleration of the paper feed roll 16. .

  Since the rotation speed of the paper feed roll 16 is gradually increased at a normal time when the paper roll 16 is pulled out when there is a remaining amount of the long paper 16a, the moving average value of the previous pulse cycle> current The moving average value of the pulse period. In the present embodiment, the difference ratio is set to a range of −10% to + 90% from the derivation formula of the difference ratio.

  On the other hand, when the end of the long paper 16a is naturally peeled off from the paper tube 60, the rotation speed of the paper feed roll 16 is rapidly reduced, so that the moving average value of the previous pulse cycle << the current pulse cycle. It becomes a moving average value. In the present embodiment, the difference ratio is set to + 90% (third threshold) or more from the difference ratio derivation formula. This corresponds to a case where the angular acceleration of the paper feed roll 16 is smaller than a predetermined threshold (negative value; first threshold).

  Further, when the end of the long paper 16a is firmly attached to the paper tube 60 and is not peeled off from the paper tube 60, the rotational speed of the paper feed roll 16 is rapidly accelerated. Value >> Moving average value of the current pulse period. In the present embodiment, the difference ratio is set to −10% or less (fourth threshold value) from the above-described difference ratio derivation formula. This corresponds to a case where the angular acceleration of the paper feed roll 16 is greater than a predetermined threshold (positive value; second threshold).

  Therefore, in the present embodiment, when the difference ratio is in the range of −10 to + 90% (−10 to + 90% in step S18), the control unit 341 performs the normal operation, that is, the end of the long paper is illustrated. It is determined that the second contact B has not been reached, the process returns to step S10, and the above-described processing is continued. That is, the conveyance of the long paper 16a is continued.

  When the difference ratio is + 90% or more (+ 90% or more in Step S18), it means that the rotation speed (angular velocity ω) of the paper feed roll 16 has suddenly decreased. It is determined that the end of the long paper 16a is slightly attached to the paper tube 60, and the end of the long paper 16a is detected, and the processing ends as it is. That is, when the end of the long paper 16a is naturally peeled off at the contact point B in FIG. 2, the printer main body 30 is configured so as to end the printing after continuing the printing to the rear end portion of the detected long paper 16a. To control.

On the other hand, when the difference ratio is −10% or less (−10% or less in step S18), it means that the rotational speed (angular velocity ω) of the paper feed roll 16 has accelerated rapidly, and thus the control unit 341. Determines that the end of the long paper 16a is firmly attached to the paper tube 60 and does not peel off naturally from the paper tube 60, and immediately increases the braking force of the powder brake 28 to increase the angular velocity (angular acceleration). Accordingly, the sheet is weakened (step S20), and the auto cutter 22 is driven via the auto cutter driving unit 342 to cut the long paper 16a (step S22). That is, when the end of the long paper 16a reaches the contact B in FIG. 2, if the paper 16 is not peeled off, the long paper 16a is cut. Then, the process ends. Note that the time from when the control unit 341 determines that the difference ratio is −10% or less until the auto cutter 22 is driven via the auto cutter driving unit 342 to cut the long paper 16a is as follows. It is shorter than the time when the glue point P _{0 at} the end of the long paper 16a reaches the contact P shown in FIG. That is, long paper 16a before gluing point P ₀ of the end of the long paper 16a reaches the contact point P will be cut. In other words, the long paper 16 a is cut by the auto cutter 22 before the drawing direction of the long paper 16 a becomes perpendicular to the outer peripheral surface of the paper tube 60. Thereafter, after the printing is continued up to the cut portion of the long paper 16a cut by the auto cutter 22, the printer main body 30 is controlled so as to end the printing.

  According to the embodiment described above, the angular velocity of the paper feed roll 16 is detected by the slit encoder 64, and the moving average of the previous pulse period corresponding to the angular acceleration of the paper feed roll 16 based on the detected change in angular velocity. Since the state of the end of the long paper 16a is determined based on the difference ratio between the value and the moving average value of the current pulse period, the end of the long paper 16a that does not peel off from the paper tube 60 is reliably detected. can do.

  Further, according to the above-described embodiment, the difference ratio between the moving average value of the previous pulse period corresponding to the angular acceleration of the paper feed roll 16 and the moving average value of the current pulse period is in the range of −10 to 90%. In some cases, it is determined that the end of the long paper has not reached the contact point B in FIG. 2, and if the difference ratio is + 90% or more, the end of the long paper 16a is slightly pasted on the paper tube 60. When the difference ratio is −10% or less, it is determined that the end of the long paper 16a is firmly attached to the paper tube 60 and does not peel off naturally from the paper tube 60. Thus, the end of the long paper 16a that does not peel off the paper tube 60 can be reliably detected.

  Further, according to the above-described embodiment, when it is determined that the end of the long paper 16a is firmly attached to the paper tube 60 and does not peel off, the braking force of the powder brake 28 is immediately increased in angular velocity (angular acceleration). ), The long paper 16a is cut, so that the forced stop of the paper conveyance can be avoided and damage to the printed product and the driving device can be reduced.

  In the embodiment described above, the slit encoder 64 outputs a pulse signal having a period corresponding to the angular velocity of the paper feed roll 16 (paper tube 60), and the angle of the paper feed roll 16 is determined from the change in the pulse period of the pulse signal. Although the difference ratio corresponding to the acceleration is derived, the angular acceleration of the paper feed roll 16 may be directly detected by an acceleration sensor or the like.

As mentioned above, although several embodiment of this invention was described, this invention is not limited to these, The invention described in the claim, and its equal range are included.
Below, the invention described in the claims of the present application is appended.

(Appendix 1)
The invention according to appendix 1 includes a detection unit that detects an angular velocity of the paper feed roll when the print medium is pulled out from a paper feed roll wound around the winding core in a roll shape; and the detection unit A deriving means for deriving an angular acceleration of the paper feed roll based on the change in the angular velocity of the paper feed roll detected by the deriving means; and A sheet feeding roll holding device comprising: a determination unit configured to determine a coupling state between an end of a print medium and the winding core.

(Appendix 2)
According to the second aspect of the present invention, when the angular acceleration of the paper feed roll is greater than a predetermined first threshold, the determination unit is configured such that the end of the print medium is coupled to the winding core. The sheet feed roll holding device according to Supplementary Note 1, wherein the sheet feeding roll holding device is determined.

(Appendix 3)
According to the third aspect of the present invention, when the determination unit determines that the end of the printing medium is coupled to the winding core, the drawing direction of the printing medium is relative to the outer peripheral surface of the winding core. The sheet feed roll holding device according to appendix 1 or 2, further comprising a cutting unit that cuts the printing medium before it becomes vertical.

(Appendix 4)
According to the fourth aspect of the present invention, when the determination unit determines that the end of the printing medium is coupled to the winding core, the printing medium is wound from the tangential direction of the outer peripheral surface of the paper feed roll. Any one of Supplementary notes 1 to 3, further comprising: a braking unit that weakens the braking of the rotation of the paper feed roll rather than braking the rotation of the paper feed roll when unlocked. There is a paper feed roll holding device described.

(Appendix 5)
The invention according to appendix 5 is an image forming apparatus including a paper feed roll holding device that holds a paper feed roll in which a printing medium is wound around a winding core. The paper feed roll holding device includes: Detection means for detecting an angular speed of the paper feed roll when the printing medium is pulled out from the paper feed roll while rotating around the winding core, and a change in the angular speed of the paper feed roll detected by the detection means Based on the derivation means for deriving the angular acceleration of the paper feed roll, and based on the angular acceleration of the paper feed roll derived by the derivation means, the connection state between the end of the printing medium and the winding core When the determination means determines that the end of the printing medium is coupled to the winding core, the drawing direction of the printing medium is perpendicular to the outer peripheral surface of the winding core. Further comprising cutting means for cutting the printing medium before become an image forming apparatus comprising: a.

(Appendix 6)
In the invention according to appendix 6, the determination unit is configured such that when the angular acceleration of the paper feed roll becomes smaller than a predetermined second threshold, the end of the printing medium is not coupled to the winding core. The image forming apparatus according to appendix 5, wherein the image forming apparatus is determined.

(Appendix 7)
According to the seventh aspect of the present invention, when the determination unit determines that the end of the printing medium is coupled to the winding core, the cutting end of the printing medium is based on the timing of cutting by the cutting unit. Printing is continued until the end of the printing medium is uncoupled from the core, and printing is continued until the end of the printing medium based on the timing of the determination. The image forming apparatus according to appendix 6, characterized in that:

(Appendix 8)
The invention according to appendix 8 is a printing control method for controlling printing on the printing medium in which the printing medium is drawn out at a predetermined speed from a paper feed roll in which the printing medium is wound around a winding core. A step of detecting an angular velocity of the paper feed roll when the printing medium is pulled out from the paper feed roll while rotating about the winding core; and a change in the detected angular velocity of the paper feed roll. A step of deriving an angular acceleration of the paper feed roll, and a step of determining a coupling state between the end of the printing medium and the winding core based on the derived angular acceleration of the paper feed roll. And a printing control method characterized by including:

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 15 Long paper feed part 16 Paper feed roll 16a Recording medium (long paper)
17, 19 Paper guide rollers 18, 18a, 18b End sensor 20 Unwinder shaft 21 Lower paper transport roller pair 22 Auto cutter 23 Upper paper transport roller pair 24 Paper passage sensor 25 Unwinder 28 Powder brake 30 Printer body (image forming section)
31, 31k, 31c, 31m, 31y Drum / developing device 32 Transfer belt device 33 Toner cartridge 34 Electrical unit 341 Control unit 342 Auto cutter drive unit 35 Paper feed unit 36 Fixing device 37 Intermediate transfer belt 38 Drive roller 39 Drive roller 40 Toner Longitudinal conveyance path 41 Secondary transfer backup roller 42 Secondary transfer roller 45 Face-up unit 47 Main body entry conveyance roller 50 Long paper take-up part 51 Take-up roll 60 Paper tube (winding core)
61 Shaft 62 Multiple slits 63 Rotating plate 64 Slit encoder

Claims (5)

Detecting means for detecting an angular velocity of the paper feed roll when the print medium is pulled out from a paper feed roll wound around the winding core in a roll shape;
Derivation means for deriving angular acceleration of the paper feed roll based on a change in angular velocity of the paper feed roll detected by the detection means;
Determining means for determining a coupling state between the end of the printing medium and the winding core based on the angular acceleration of the paper feed roll derived by the deriving means;
If the determination means determines that the end of the printing medium is coupled to the winding core, the feeding medium is unwound when the printing medium is unwound from the tangential direction of the outer peripheral surface of the paper feed roll. Braking means for weakening the rotation of the paper feed roll rather than braking the rotation of the paper roll;
A paper feed roll holding device. The determination means includes
When the angular acceleration of the paper feed roll is greater than a predetermined first threshold, it is determined that the end of the printing medium is coupled to the winding core.
The paper feed roll holding device according to claim 1. If the determination means determines that the end of the printing medium is coupled to the winding core, the covering medium is drawn before the drawing direction of the printing medium becomes perpendicular to the outer peripheral surface of the winding core. A cutting means for cutting the print medium;
The sheet feeding roll holding device according to claim 1, wherein the sheet feeding roll holding device is provided. An image forming apparatus including a paper feed roll holding device that holds a paper feed roll in which a printing medium is wound around a winding core.
The paper feed roll holding device is
Detecting means for detecting an angular velocity of the paper feed roll when the print medium is pulled out from the paper feed roll while rotating around the winding core;
Derivation means for deriving angular acceleration of the paper feed roll based on a change in angular velocity of the paper feed roll detected by the detection means;
Determining means for determining a coupling state between the end of the printing medium and the winding core based on the angular acceleration of the paper feed roll derived by the deriving means;
If the determination means determines that the end of the printing medium is coupled to the winding core, the covering medium is drawn before the drawing direction of the printing medium becomes perpendicular to the outer peripheral surface of the winding core. Cutting means for cutting the print medium ,
The determination means includes
When the angular acceleration of the paper feed roll becomes smaller than a predetermined second threshold, it is determined that the end of the printing medium is not coupled to the winding core;
The image forming apparatus includes:
If the determination unit determines that the end of the printing medium is coupled to the winding core, the printing is continued until the cutting end of the printing medium based on the timing of cutting by the cutting unit,
If the determination means determines that the end of the printing medium is not coupled to the winding core, printing is continued until the end of the printing medium based on the timing of the determination.
An image forming apparatus. A printing control method for controlling printing on the printing medium in which the printing medium is pulled out at a predetermined speed from a paper feed roll in which the printing medium is wound around a winding core,
Detecting an angular velocity of the paper feed roll when pulling out the printing medium while rotating about the winding core from the paper feed roll;
Deriving an angular acceleration of the paper feed roll based on the detected change in angular velocity of the paper feed roll;
Determining a coupling state between the end of the printing medium and the winding core based on the angular acceleration of the paper feed roll derived;
When it is determined that the end of the printing medium is coupled to the winding core, the rotation of the paper feeding roll is performed when the printing medium is unwound from the tangential direction of the outer peripheral surface of the paper feeding roll. Weakening braking of the rotation of the paper feed roll, rather than braking
A printing control method comprising:

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