JP2007163946A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device wherein two rotating members hardly slip when being pressurized and can be rotated at a desired speed even when being not pressurized. <P>SOLUTION: The fixing device includes; a driving means 15 for driving a rotating member 1; a driving means 21 for driving a rotating member 2; a comparison and control means 14 which compares a detected speed detected by a speed detection means 12 with a target speed and increases/decreases a driving amount of a driving means 15 so as to make the detected speed equal to the target speed; a comparison and control means 20 which compares a detected speed detected by a speed detection means 18 with a target speed and increases/decreases a driving amount of a driving means 21 so that the detected speed is equal to the target speed; a comparison and control means 22 which compares a detected torque detected by a torque detection means 24 with a target torque and increases/decreases the driving amount of the driving means 21 that the detected torque is equal to the target torque; and a control switching means which enables the comparison and control means 22 and disables the comparison and control means 20, during pressurizing and enables the comparison and control means 20 and disables the comparison and control means during pressure release. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing device that is used in a copying machine, a printer, or the like, and obtains a fixed image by passing a sheet on which an unfixed toner image is placed between two rotating bodies that are mutually pressurized. The present invention relates to the driving of the rotating body.

  2. Description of the Related Art Conventionally, in a fixing device, toner can be efficiently fixed by applying pressure to upper and lower rotating bodies. In addition to printing, there are those that rotate during standby to equalize heat.

  In the rotation during the standby, there are those in which the mutual pressures of the rotating bodies are released to reduce the fatigue of the parts and improve the durability. In a certain fixing drive, a driving force is transmitted from a motor to one of the upper and lower rotating bodies, and the other is driven by friction from the rotating body to which the driving force is applied. However, when the mutual pressures of the rotating bodies are released, the driven side stops, so the driving force is transmitted from the motor to the driven side at a slightly slower speed than the driven speed by the 1-way clutch. It is like that.

  In another fixing drive, there is one that gives driving force to both the upper and lower rotating bodies via a gear from one motor that rotates at a predetermined speed. In this case, the surface speed of the upper and lower rotating bodies is the same. The gear ratio is taken into consideration.

  Another fixing drive may be one in which two motors provide driving force to the upper and lower rotating bodies. In this case, the rotational speeds of the two motors are set so that the surface speeds of the upper and lower rotating bodies are the same. Consider the gear ratio.

In addition, as a bridle roll control device, there is one that determines the torque sharing ratio of a plurality of motors and controls the overall speed (see, for example, Patent Document 1).
JP 7-330198 A

  If only one of the upper and lower rotating bodies is provided with a driving force by a motor that rotates at a predetermined speed, and the other is driven by friction from the rotating body to which the driving force is applied, a slip will occur. When not, the surface speeds of the upper and lower rotating bodies are the same. However, since the driving force is transmitted by friction between the rotating bodies, slipping is likely to occur, and naturally slipping causes a difference in speed. This speed difference causes the unfixed toner image to rub.

  In addition, a driving force is applied to both the upper and lower rotating bodies via a gear from a motor that rotates at a predetermined speed, and the gear ratio is considered so that the surface speeds of the upper and lower rotating bodies are the same. When the thermal expansion or molding error of the rotating body occurs, a difference occurs in the surface speed between the upper and lower rotating bodies. This phenomenon gives driving force to the upper and lower rotating bodies with the two motors, and considers the rotational speed and gear ratio of the two motors so that the surface speeds of the upper and lower rotating bodies are the same. It occurs in the same way.

  When the overall speed is controlled by determining the torque sharing ratio of a plurality of motors, the speed control can be established if the entire drive is always connected by friction. However, in the fixing device of the copying machine, the pressure may be released as described above. At this time, the drive is not connected, so the speed of the portion where the speed is not monitored becomes uncontrolled.

  The present invention has been made under such circumstances, and provides a fixing device that is difficult to slip when two rotating bodies are pressurized, and that can rotate at a desired speed even when it is not pressurized. It is an object to do.

  In order to solve the above-described problem, in the present invention, the fixing device is configured as described in (1) below.

  (1) The rotating body 1, the rotating body 2, the pressurizing means for applying pressure by bringing the rotating body 1 and the rotating body 2 into contact with each other, and separating the rotating body 1 and the rotating body 2 to release the pressure. Pressure releasing means for driving, driving means 1 for rotationally driving the rotating body 1, driving means 2 for rotationally driving the rotating body 2, speed detecting means 1 for detecting the speed of the rotating body 1, and the rotation The speed detection means 2 for detecting the speed of the body 2, the torque detection means 2 for detecting the torque of the drive means 2, and the detected speed detected by the speed detection means 1 and the target speed are compared and matched. The comparison control means 1 for raising and lowering the drive amount of the drive means 1 and the comparison control means 2 for raising and lowering the drive amount of the drive means 2 so that the detection speed detected by the speed detection means 2 is compared with the target speed. And the detection torque detected by the torque detection means 2 The comparison control means 3 for raising and lowering the drive amount of the drive means 2 so that the target torque is compared with the target torque, and the comparison control means 3 is made effective at the time of pressurization by the pressurization means. And a control switching unit that disables the comparison control unit 2 and disables the comparison control unit 3 when the pressure is released by the pressure release unit.

  According to the present invention, when the rotating bodies are pressurized, the amount of transmission force transmitted by the friction between the rotating bodies is small, so that it is difficult to slip, and even when not pressurized, it can rotate at a desired speed.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to an embodiment of a fixing device.

  The “fixing device” according to the first embodiment will be described with reference to FIGS.

  FIG. 2 is a diagram showing the state of the fixing device during printing, in which 1 is a motor and drives the roller 3 in the direction of the arrow. The driving of the roller 3 is transmitted to the belt 5 so that the belt 5 is also rotated. Reference numeral 7 denotes a roller that applies tension to the belt 5 and receives a driving force from the belt 5 to carry it around. Reference numeral 2 denotes a motor which drives the roller 4 in the direction of the arrow. The driving of the roller 4 is transmitted to the belt 6 so that the belt 6 is also rotated. Reference numeral 8 denotes a roller that applies tension to the belt 6 and is driven by the driving force from the belt 6. A pressure is applied between the roller 3 and the roller 4. A pressure is also applied between the roller 7 and the roller 8. Reference numerals 9 and 10 denote pressure pads, which are arranged so as to face the inner surfaces of the belt 5 and the belt 6, and pressure is applied thereto. Due to these pressures, a pressure is generated between the belt 5 and the belt 6. The belt 5 and the belt 6 are heated to a high temperature. When the recording paper 11 on which an unfixed toner image is placed passes from the right to the left in the direction of the arrow, the toner image is fixed to the recording paper 11 by heat and pressure.

  FIG. 3 is a diagram illustrating a state of the fixing device when printing is not in progress, in standby, or when a jam occurs. Compared to the pressure applied in FIG. 2, the belt 5 and the belt 6 are separated in FIG. 3 to release the pressure.

  FIG. 1 is a block diagram showing the configuration of the control system of this embodiment. The speed of the motor 1 is detected by the speed detection circuit 12, compared by the comparator 14 so as to coincide with the target speed 13, and driven by the drive circuit 15. Driving and stopping are controlled by an ON / OFF signal 16. The current detector 17 detects the drive current of the drive circuit 15. The detected current is proportional to the torque of the motor 1.

  When SW1 of the switch 26 is ON and SW2 is OFF, the speed of the motor 2 is detected by the speed detection circuit 18 and is compared by the comparator 20 so as to coincide with the target speed 19, and is driven by the drive circuit 21. When SW1 of the switch 26 is OFF and SW2 is ON, the current detected by the current detector 17 is multiplied by a constant gain by the multiplication block 25, and the drive current of the drive circuit 21 is converted by the current detector 24. The detected ones are compared, and the motor 2 is driven by the drive circuit 21 so that they match. The current value detected by the current detector 24 is proportional to the torque of the motor 2. That is, the motor 2 is controlled to a torque obtained by multiplying a constant gain of the torque of the motor 1. Driving and stopping are controlled by the ON / OFF signal 23.

  4 shows a microcomputer 27, and the microcomputer 27 outputs a signal to the block shown in FIG. First, the target speed 13 is output. An ON / OFF signal 16 is output. A target speed 19 is output. An ON / OFF signal 23 is output. The state of SW1 and SW2 of the switch 26 is switched. How these are output will be described in the next flow.

  FIG. 5 is a main flow of the microcomputer 27. Step 102 (abbreviated as S102, the same applies hereinafter) is an initial setting in which the operation mode is set to standby 1. S103 processes the transition of the operation mode, and switches between the three operation modes of standby 1, standby 2, and printing. S104 is a part of sequence control most relevant to the description of the present invention. S105 is other processing.

  FIG. 6 is a detailed flow of part S104 of the most relevant sequence in the description of the present invention. It is determined whether printing is in progress (S202), next it is determined whether it is standby 1 (S203), and then standby. Whether it is 2 or a jam is determined (S204).

  Here, the standby 1 is a standby state in which the fixing heating is performed and the waiting time is short with respect to the print request, and the standby 2 is a standby state in which the fixing heating is not performed and the printing request is long. It is waiting to be able to print at a later time.

  When printing is in progress in the previous determination S202, the fixing device is set to the pressure state shown in FIG. 2 (S205), the fixing device is heated (S206), and the motor 1 is rotated at high speed, that is, the target speed. 13 is set to high speed and ON / OFF 16 is turned ON (S207). Then, the switch 2 of the switch 26 is turned off, the switch SW2 is turned on, and the switch ON / OFF 23 is turned on so that the motor 2 performs current control (S208). Thereby, the torque of the motor 2 is controlled in proportion to the torque of the motor 1. At this time, the target speed 19 does not affect the driving of the motor because SW1 is OFF.

  If the standby state 1 is determined in the previous determination S203, the pressure is released as shown in FIG. 3 (S209), the fixing device is heated (S210), and the motor 1 is rotated at a low speed. That is, the target speed 13 is lowered and the ON / OFF 16 is turned on (S211). Then, so that the motor 2 performs speed control, SW1 of the switch 26 is turned ON, SW2 is turned OFF, ON / OFF 23 is turned ON, and the target speed 19 is set to a low speed (S212). As a result, the motor 1 is driven independently at the target speed 13 and the motor 2 is driven independently at the target speed 19.

  In the case of standby 2 or jam in the previous judgment S204, the pressurization is released as shown in FIG. 3 (S213), the fixing device is turned off (S214), and the motor 1 is turned on to stop. / OFF16 is turned OFF (S215), and ON / OFF23 is turned OFF to stop the motor 2 (S216). As a result, the fixing device is not overheated or rotated. As described above, during printing, the motors 1 and 2 operate at a high speed so as to achieve a paper conveyance speed necessary for printing. However, in the standby 1, the motors 1 and 2 are operated at a low speed such that the temperature distribution is uniform. Operate. In standby 1, the paper is not transported and the pressure on the toner on the paper is not required, so the pressure is released.

  FIG. 7 is a flow for processing the transition of the operation mode, and it is determined whether the current operation mode is standby 1 (S302), printing (S303), or standby 2 (S304). In the case of standby 1 in the previous determination S302, when the status of standby 1 has passed for a certain time (S305), the operation mode is shifted to standby 2 (S306), which is a shift to the energy saving mode. If the predetermined time has not elapsed in the previous determination S305, it is determined whether there is a print request (S307). If there is a request, it is further determined whether the temperature exceeds 180 ° C. That is, it is determined whether the temperature is sufficient for printing (S308), and if it exceeds 180 ° C., the operation mode is shifted to printing (S309). When the previous determinations S307 and S308 are not, the process ends with the current operation mode maintained (S314).

  In the previous determination S303, when the current operation mode is printing, when printing is completed (S310), the mode is shifted to standby 1 (S311). If not in the previous determination S310, the process ends with the current operation mode maintained (S314). When the operation mode is standby 2 in the previous determination S304 and there is a print request (S312), the operation mode is shifted to standby 1 (S313), otherwise the current operation mode is maintained in the previous determination S312. The process ends (S314).

  FIG. 8 shows the relationship between the drive current and torque of the motor 1 and the motor 2, which is proportional.

  FIG. 9 shows an example of changes in the drive currents of the motor 1 and the motor 2 during printing. When the torque changes, the drive current of the motor 1 and the drive current of the motor 2 change, but the ratio is always the same. It shows how it is controlled in this way. The ratio of the driving current Ia1 of the motor 1 to the driving current Ib1 of the motor 2 at time T1 is 2: 1, and the ratio of the driving current Ia2 of the motor 1 to the driving current Ib2 of the motor 2 at time T2 is also 2: 1. .

  FIG. 10 is a time chart showing an example of a series of operations in which the operation mode, the pressurization state, the heating state, the operation state of the motor 1 and the operation state of the motor 2 change. When the power is turned on, the operation mode is set to standby 1. At that time, the pressurization is released and heated, the motor 1 rotates at a low speed, and the motor 2 rotates at a low speed by speed control. When there is a print request and printing starts, the operation mode shifts to printing, pressurization and heating are performed, the motor 1 rotates at a high speed, and the motor 2 has a current that is a predetermined ratio of the motor 1 (in this embodiment, half). It is controlled to become. When printing is completed, the operation mode shifts to standby 1, at which time the pressurization is released and heated, the motor 1 rotates at a low speed, and the motor 2 rotates at a low speed by speed control. When the standby 1 state elapses for a certain period of time, the system shifts to energy saving and the operation mode becomes standby 2. At that time, the pressurization is released, the heating is turned off, and the motor 1 and the motor 2 are stopped.

As described above, according to the present embodiment, during the printing in which the rotators are pressurized, only the rotator 1 is controlled in speed, and the surface speed of the rotator 2 is determined by the friction between the rotators. It becomes the same as the surface speed. In this case, since both the rotator 1 and the rotator 2 have drive sources, the amount of driving force transmitted by friction between the rotators is reduced. Further, since the speeds of the respective motors are controlled during standby in which the pressurization between the rotating bodies is released, the speed of one of the rotating bodies is not controlled and the speed is stabilized.
That is, during printing, since the amount of driving force transmitted by the friction between the rotating bodies is small, it is difficult to slip and can rotate at a desired speed even in a standby state where no pressure is applied.

  FIG. 11 is a block diagram illustrating the configuration of the control system of the “fixing apparatus” according to the second embodiment. A difference from the first embodiment will be described with reference to FIG. FIG. 11 is a diagram of replacement of FIG. 1 of the first embodiment, in which the switching circuit SW2 is ON and SW1 is OFF during pressurization during printing. At this time, the current detected by the current detector 24 by the current detector 24 is compared with the target current 201 and operates so as to match. FIG. 12 is a diagram of the replacement of FIG. 4 of the first embodiment, and the microcomputer 27 outputs the previous target current 201 as shown in FIG.

  As described above, according to the present embodiment, the same effects as those of the first embodiment can be obtained.

FIG. 1 is a block diagram illustrating a configuration of a control system according to the first embodiment. The figure which shows the state of the fixing device at the time of pressurization Diagram showing the state of the fuser when pressure is released Block diagram around the microcomputer Flowchart showing the main flow of the microcomputer The flowchart which shows the detailed flow of S104 in a main flow. Flow chart showing the flow for processing the operation mode transition Diagram showing the relationship between motor drive current and torque The figure which shows an example of the change of the drive current of the motor 1 and the motor 2 during printing Time chart showing one example of a series of operations in which the operation mode, the pressurization state, the heating state, the operation state of the motor 1 and the operation state of the motor 2 change. The block diagram which shows the structure of the control system of Example 2. FIG. Block diagram around the microcomputer of the second embodiment

Explanation of symbols

1, 2 Motor 12, 18 Speed detection circuit 13, 19 Target speed interface circuit 14, 20, 22 Comparator 15, 21 Drive circuit 16, 23 ON / OFF signal interface circuit 17, 24 Current detector 25 Gain adjuster 26 Switching 201 Target current interface circuit

Claims (4)

  Rotating body 1, rotating body 2, pressurizing means for applying pressure by bringing the rotating body 1 and the rotating body 2 into contact with each other, pressurizing for separating the rotating body 1 and the rotating body 2 and releasing the pressure A release means, a drive means 1 for rotationally driving the rotary body 1, a drive means 2 for rotationally driving the rotary body 2, a speed detection means 1 for detecting the speed of the rotary body 1, and the rotary body 2 The speed detection means 2 for detecting the speed, the torque detection means 2 for detecting the torque of the drive means 2, and the drive means 1 so that the detection speed detected by the speed detection means 1 and the target speed are compared and matched. The comparison control means 1 for raising and lowering the drive amount, the comparison control means 2 for raising and lowering the drive amount of the drive means 2 so that the detection speed detected by the speed detection means 2 and the target speed coincide with each other, The detected torque detected by the torque detecting means 2 and The comparison control means 3 for raising and lowering the drive amount of the drive means 2 so that the target torques are matched and matched, and at the time of pressurization by the pressurization means, the comparison control means 3 is enabled and the comparison control means 2 is disabled. And a control switching means for enabling the comparison control means 2 and disabling the comparison control means 3 when releasing the pressure by the pressure release means. The fixing device according to claim 1,
The fixing device according to claim 1, wherein the torque detection unit 2 detects torque based on a drive current of the drive unit 2. The fixing device according to claim 1,
A fixing device comprising: torque detection means 1 for detecting torque based on a drive current of the drive means 1; and determining the target torque based on the drive torque detected by the torque detection means 1. The fixing device according to claim 3.
A fixing device characterized in that a value obtained by multiplying a driving torque detected by the torque detecting means 1 by a predetermined ratio is set as the target torque.

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