JP2009186854A - Heat roll drive control system for continuous paper electrophotographic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the printing quality from deteriorating due to slur and scattering of characters, since a heat roll has a difference in the paper delivery quantity per rotation, due to the difference in the type and shape variations which are generated temporally or thermally in the heat roll and the behavior of a buffer increases, when feeding of the paper is started/stopped. <P>SOLUTION: When a heat roll motor for driving the heat roll attains a fixed rotation speed, after the heat roll motor begins to be rotated, angle sensor information is stored, and the timing, when the heat roll motor for driving the heat roll begins to be rotated next, is set based on the stored angle sensor information. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat roll drive control system for a continuous paper electrophotographic apparatus.

  FIG. 1 is a schematic configuration diagram of the paper transport mechanism. The paper transport mechanism unit includes two pairs of sandwiching rolls 10 and 16, a buffer plate 11 that applies tension to the paper therebetween, and a buffer unit angle sensor 12 that detects the angle of the buffer plate 11. A pair of nipping rolls positioned upstream of the process of transporting the paper 15 is the paper transport roll driving unit 13 and serves as a reference for the paper transport speed. Then, another pair of sandwiching rolls 10 located downstream is carrying the paper while the toner image on the paper 15 is heated / pressurized and fixed by the heat roll driving unit 14 (see, for example, Patent Document 1). ).

  The structure of the heat roll 10 that heats / pressurizes the toner image on the paper 15 is coated with a thin film on the surface in order to improve adhesion, and there is a solid difference in the amount of paper transported per rotation, and the shape of the heat roll 10 increases with time of use. Changes. Further, the paper 15 may be shrunk when heated, and slippage may occur with the heat roll 10. Accordingly, since the peripheral speed of the heat roll 10 of the heat roll driving unit 14 and the paper conveyance amount do not match, the buffer buffer angle sensor 12 detects the paper buffer amount between the paper conveyance roll driving unit 13 and the heat roll driving unit 14, Paper transport control is performed by a method of adjusting the drive speed of the heat roll drive unit 14 so that the paper buffer amount becomes constant.

  FIG. 2 is a control block diagram of the pinless paper transport mechanism, and the control contents will be described below. The paper transport roll driving unit 13 includes a paper transport motor 20 provided with a paper transport roll 16 and a paper transport motor encoder 21 and a paper transport motor control unit 23. The paper transport motor encoder signal 22 and the paper transport motor control reference clock 24 are made to compete, and when the number or phase of the encoder signal is “delayed” with respect to the reference clock, the paper transport motor 20 is driven. Obtains the paper transport roll drive speed in a non-driven manner. In order to be a standard for paper conveyance, the dimensional accuracy of the circumference of the paper conveyance roll 16 is important, and a material with high processing accuracy, wear resistance, and shape stability is used.

  The heat roll drive unit 14 includes a heat roll motor 27 equipped with a heat roll 10 and a heat roll motor encoder 28, and a heat roll motor control unit 30. In the heat roll drive control, similarly to the paper transport roll drive control, the paper transport control is performed by a method in which the heat roll motor encoder signal 29 and the heat roll motor control reference clock 31 compete with each other. Since the heat roll 10 heats / pressurizes the paper, the heat roll 10 expands and contracts and is deformed by its own heat and the like, so the paper feed amount of the heat roll 10 changes every moment. In order for the heat roll drive unit 14 to send out the same amount as the feed amount of the paper transport roll drive unit 13, it is essential to control the drive speed of the heat roll 10, and the CPU 25 sets the reference clock 31 for heat roll motor control. The drive speed is changed by a method of dividing by the count number N.

  The buffer unit angle sensor 12 detects the angle of the buffer plate 11 that applies tension to the paper spanned between the paper transport roll driving unit 13 and the heat roll driving unit 14, and outputs a buffer angle sensor signal 26. The relationship between the buffer plate angle and the paper buffer amount is uniquely determined from the mechanical arrangement, and the CPU 25 knows the paper buffer amount from the buffer plate angle.

FIG. 3 is a characteristic diagram of buffer angle vs. paper buffer amount and paper buffer amount vs. heat roll driving speed. As shown in FIG. 3, the buffer angle θ ₀ is set as the neutral position, and the sheet buffer amount at this time is F ₀ . When the buffer angular changes in theta _1, the paper buffer amount of theta ₁ is since it is _{F 1,} the change of the paper buffer amount ΔL ₂ = _F 1 -F ₀ is obtained. Since the paper buffer amount in the buffer angle theta ₁ is increased [Delta] L _2, increasing the sheet conveying amount by the driving speed of the heat roll increases the driving speed of the switching heat roll from V _{2 (θ 0)} V ₂ to _{(theta 1)} . Conversely, when the buffer amount decreases, control is performed to reduce the sheet conveyance amount by lowering the driving speed of the heat roll.

  Currently, there is an operation method for properly using the heat roll 10 in accordance with applications such as high speed and high image quality. For high speed applications, a heat roll using a thin, hard Teflon (registered trademark) material that is advantageous in terms of heat transfer speed and stable paper feeding is selected. For high image quality use, a heat roll using a soft rubber material with a thick film that wraps a toner image without being crushed and gives heat is selected. Since these different types of heat rolls have different sheet feed amounts due to differences in film thickness and material, as shown in Patent Document 1, the actual heat roll 10 is determined from the angle of the buffer plate 11 when the paper is being conveyed. Control for reducing the movement of the buffer plate 11 by changing the target constant speed rotation speed of the heat roll 10 is known.

  However, when starting up the heat roll motor 27 at the start of paper conveyance, since full acceleration is performed, the paper of the paper conveyance roll drive unit 13 and the heat roll drive unit 14 before shifting to a constant speed operation. There is a case where the difference in the transport amount causes the behavior of the buffer plate 11 to increase, which may cause character blurring that causes the printing in the transport direction to become dense and scattering that causes the toner image to collapse.

JP 2004-211985 A1

  In view of the above problems, an object of the present invention is to prevent a decrease in print quality due to character blurring or scattering due to a change in the behavior of a buffer at the start / stop of paper conveyance.

  The above-described problems include a paper transport roll that is a reference for the paper transport speed, a paper transport roll driving unit that drives the paper transport roll, a buffer plate, a buffer unit angle sensor, a heat roll, and a drive for the heat roll. A heat roll driving unit, tensioning the paper spanned between the paper conveyance roll driving unit and the heat roll driving unit with the buffer plate, and driving the heat roll with respect to the paper conveyance roll driving unit The buffer plate falls when the section overfeeds the paper, and the buffer section angle sensor detects a state that occurs when the section is not fed, and the speed of the heat roll driving section is adjusted so that the buffer section angle sensor information becomes a predetermined value. In the heat roll drive control of the continuous paper electrophotographic apparatus that adjusts, the heat roll drive unit is a servo motor, This is achieved by storing the angle sensor information when the servo motor reaches a certain number of rotations after starting rotation, and setting the timing at which the servo motor starts to rotate next based on the stored angle sensor information. Is done.

  According to the present invention, it is possible to prevent deterioration in print quality due to paper conveyance failure and character blurring and scattering due to a change in buffer behavior at the start / stop of paper conveyance.

  Embodiments of the present invention will be described below with reference to FIGS. The relationship between the sheet conveyance mechanism unit in FIG. 1, the control block of the sheet conveyance mechanism unit in FIG. 2, and the buffer angle versus sheet buffer amount and sheet buffer amount versus heat roll drive speed in FIG. Is omitted.

FIG. 4 shows the relationship between the sheet conveyance speed by the sheet conveyance roll driving unit 13, the sheet conveyance speed by the heat roll driving unit 14, and the buffer angle. 4, to start sheet conveyance of the sheet conveying roll drive section 13 and the heat roll drive section 14 at the timing indicated by t _0. Detecting a buffer angle when the sheet conveying speed of the heat roller drive unit 14 has reached a specified speed V _1. The sheet conveyance speed by the heat roll driving unit 14 changes with time. When the paper slip at the heat roll drive unit 14 is large, the characteristic is as indicated by 46 in FIG. 4, and when the diameter of the heat roll is increased due to thermal expansion, the characteristic is as indicated by 43. . The buffer angle C when the paper transport speed by the heat roll drive unit 14 reaches the specified speed V ₁ is surrounded by the characteristics 43 from point A to point B in FIG. 4 and the paper transport speed 45 by the paper transport roll drive unit 13. That is, the difference between the sheet conveyance amount in the sheet conveyance roll driving unit 13 and the sheet conveyance amount in the heat roll driving unit 14 generated between t ₀ and t ₁ . Based on the buffer angle detected at the timing t ₁ , when the next sheet conveyance is started, the sheet conveyance by the heat roll driving unit 14 is started at the timing t ₀ when the sheet conveyance roll driving unit 13 starts the sheet conveyance. Change the timing.

FIG. 5 shows a change in the buffer angle when the timing at which the heat roll driving unit 14 starts the sheet conveyance is changed. For example, when the paper conveyance speed 44 by the heat roll driving unit 14 that has started paper conveyance at the same timing t0 as the paper conveyance roll driving unit 13 is substantially equal to the paper conveyance speed 45 by the paper conveyance roll driving unit 13, the buffer angle change 40 since few, the following also starts the paper feeding by the heat roll drive section 14 at the same timing t _0. When the paper slip with the heat roll drive section 14 is large, becomes a characteristic as indicated at 46 in FIG. 4, when detecting that up buffer angle t ₃ is, then start the paper conveying The timing at the heat roll driving unit 14 is advanced at the timing to start and the timing is started at the timing t ₄ , so that the characteristics shown by 52 in FIG. 5 are obtained, and the behavior of the buffer plate 11 is made smaller than the characteristics 41. be able to. Further, if the diameter of the heat roller is increased by the thermal expansion becomes a characteristic as shown by 43 in FIG. 4, when detecting that the lowered buffers angle t ₁ is then paper transport to slow the timing of a heat roll drive section 14 at the timing of starting by starting at the timing t _5, it becomes the characteristic as indicated by 51 in FIG. 5, reducing the behavior of the buffer plate 11 as compared with the characteristic 43 can do.

By changing the timing of starting the sheet conveyance of the heat roll drive section 14, and heat roller 10 reaches the specified speed V _1, it is possible to reduce the difference in the sheet conveyance amount until time of starting the control by the buffer angle Therefore, the behavior of the buffer plate at the start of conveyance can be reduced.

It is a schematic block diagram of a paper transport mechanism. FIG. 6 is a control block diagram of a paper transport mechanism unit. FIG. 6 is a characteristic diagram of buffer angle vs. paper buffer amount and paper buffer amount vs. heat roll driving speed. FIG. 6 is a relationship diagram of a sheet conveyance speed and a buffer angle by a sheet conveyance roll driving unit and a heat roll driving unit (when the sheet conveyance of the sheet conveyance roll driving unit and the heat roll driving unit is started simultaneously). FIG. 6 is a relationship diagram of a sheet conveyance speed and a buffer angle by a sheet conveyance roll driving unit and a heat roll driving unit (the sheet conveyance start timing of the heat roll driving unit is changed with respect to the sheet conveyance start timing of the sheet conveyance roll driving unit. If).

Explanation of symbols

  11 is a buffer plate, 12 is a buffer unit angle sensor, 13 is a paper transport roll drive unit, 14 is a heat roll drive unit, 15 is paper, 16 is a paper transport roll, 17 is a heat roll, 20 is a paper transport motor, and 21 is Paper transport motor encoder, 22 is a paper transport motor encoder signal, 23 is a paper transport motor controller, 24 is a reference clock for controlling the paper transport motor, 25 is a CPU, 26 is a buffer angle sensor signal, 27 is a heat roll motor, and 28 is A heat roll motor encoder, 29 is a heat roll motor encoder signal, 30 is a heat roll motor control unit, and 31 is a heat roll motor control reference clock.

Claims (1)

A paper transport roll serving as a reference for the paper transport speed, a paper transport roll drive unit that drives the paper transport roll, a buffer plate, a buffer unit angle sensor, a heat roll, and a heat roll drive unit that drives the heat roll Tension is applied to the paper spanned between the paper transport roll drive unit and the heat roll drive unit by the buffer plate, and the heat roll drive unit feeds the paper to the paper transport roll drive unit. When the paper is fed too much, the buffer plate falls down, and a state that occurs when the buffer plate is not fed is detected by the buffer part angle sensor, and the speed of the heat roll drive part is adjusted so that the buffer part angle sensor information becomes a predetermined value. In heat roll drive control of an electrophotographic apparatus,
The heat roll drive unit is a servo motor, stores the angle sensor information when the servo motor reaches a certain number of rotations after starting rotation, and the servo motor is then moved by the stored angle sensor information. A heat roll drive control system for a continuous paper electrophotographic apparatus, characterized in that a timing for starting rotation is set.

Images