JPH04246043A - Load connecting method of stepping motor - Google Patents

Abstract

PURPOSE:To provided such a means that makes the self-starting of a stepping motor performable even in a state of load being imposed on the motor, in a device which drives equipment with this stepping motor in such one as an image former or the like. CONSTITUTION:A connecting member 1 is set up in an interval between a driving side by a stepping motor 11 and a driving shaft 18 connected with load, and also there are provided a driving side member 2 with a groove as this connecting member 1 and a driven side member 5 with a claw member. Then, the connecting member 1 is stopped at a position, where the claw member 6 is not made contact with a pressing surface of a receiving groove 3, in advance, and when the motor is started, it is made startable in a state of being no load.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a drive device for an image forming apparatus such as a copying machine or a printer, and in particular, a connection disposed between a motor and a driven member when driving using a stepping motor. The present invention relates to a device in which the stepping motor is configured to be able to start the stepping motor without a load, and the stepping motor is brought into a self-startable state so that the driving can be started.

0002

2. Description of the Related Art Image forming apparatuses that use an electrophotographic process, such as copying machines and printers, form a toner image on an image carrier, transfer the toner image onto paper, and fix it through a fixing device. and is making a copy. In the image forming apparatus, for example, the photosensitive drum as an image carrier and the paper transport device are driven at a constant speed and in synchronization to accurately control the position at which the toner image is transferred to the paper. It is necessary to do so. Also,
In order to accurately position the paper in correspondence with the leading edge of the toner image at the position where the toner image is transferred from the photoreceptor, for example, as shown in Japanese Patent Laid-Open No. 2-28667, the position of the paper is adjusted. The use of control means is performed.

The sheet positioning means shown in the conventional example uses a registration gate, and the sheet is temporarily stopped by the gate, and the gate is opened in synchronization with the toner image formed on the photoreceptor, and the image is Control is performed to send the paper toward the transfer section, so that the position of the image relative to the paper can be accurately controlled. In addition, in the conventional example, the paper transport roller disposed downstream of the gate starts to be driven before the gate is opened, and the paper is transported at a constant speed. Make sure that it enters the nip between the conveyance rollers. Therefore, the sheet of paper sent toward the image transfer section by the conveyance roller passes through the image transfer section at a constant speed, and the toner image is transferred thereto.

On the other hand, there are cases where a roller nip type device is used as a paper conveyance means that controls the feeding of paper without using a gate. In the case of this roller nip type device, the leading edge of the paper is temporarily stopped with the roller device placed immediately before the image transfer section nipped, and the timing is adjusted to the toner image on the photoreceptor. A means is used to simultaneously drive rollers and send out the paper. In order to drive the roller, a stepping motor is used as the drive motor, and a control device applies a drive pulse that increases the speed step by step to drive the stepping motor. We are trying to control the

Furthermore, in the image forming apparatus as described above, a drive mechanism using a general DC motor, a stepping motor, etc. is arranged not only for the paper conveyance system but also for the photoreceptor and other driven members. A means for driving each member is used. For members whose rotations need to be particularly precisely controlled, a stepping motor or the like is used to control the drive thereof.

[0006]

[Problems to be Solved by the Invention] However, in the drive device using the conventional stepping motor as described above, when an attempt is made to start driving the stepping motor under a load, the motor may step out. hand,
A problem arises in that the rotation cannot be well controlled. In addition, immediately after the stepping motor is stopped, the stepping motor rotates excessively due to the rotational inertia of the driven member, and when the next drive pulse is applied, the rotation start position of the motor cannot be set accurately. There may be a problem of it disappearing.

When the stepping motor loses synchronization as described above, the control device increases the drive pulses applied to the motor step by step in an attempt to increase the rotational speed of the stepping motor to a predetermined speed. Also, a problem arises in that the rotational speed of the motor is not increased accurately. Since the rotational speed of the stepping motor does not rise to a constant value, the driving speed of the driven member cannot be maintained constant. For example, if the driven member is placed immediately before the image transfer section, In the case of a paper conveyance roller that is similar to the above, the paper feed speed at the image transfer section fluctuates. The problem is that when a photoconductor is driven at a constant speed, if there is a fluctuation in the moving speed of the paper, the transferred toner image is disturbed, making it impossible to obtain a copy in good condition. Occur.

In a general stepping motor, as shown in the graph of FIG. 8, when looking at the relationship between load torque and frequency, at a certain frequency f, self-starting is possible when the load is below t1. When a load is applied between t1 and t2, it can be used depending on the load value. In other words, in this case, the torque (load) below the range of curve a
is given, self-start will occur. Also,
If the load exceeds t2, the range of curve b is exceeded, and the motor has a characteristic of causing step-out.

[0009] Furthermore, in order to drive the stepping motor normally even when a load is applied to it, for example, the stepping motor is constructed of a large size,
The problem can also be solved by increasing the driving force. However, the stepping motor used in general image forming devices has limitations such as the manufacturing cost of the device and the storage space for the drive device, so it is difficult to make the stepping motor as small as possible and with enough driving force to achieve its purpose. I am using one with Therefore, using a large-sized stepping motor with a large driving force will have a large effect on the structure of other devices arranged inside the image forming apparatus.

0010

[Object of the Invention] The present invention solves the problem of the drive device using a stepping motor as described above. The object is to provide a means for configuring a connection so that the stepper motor can initially be started in an unloaded state and then a load can be connected.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a driving device that uses a stepping motor having an excitation circuit and that includes connecting means between the output shaft of the motor and the input shaft of a driven member. In the stepper motor load connection method of the present invention, a margin is set between the members constituting the connection means, and both members are arranged, and when starting the stepping motor, the stepping motor is driven without load, and then the load is applied. It is configured to control the connection. Further, in the present invention, a control means is provided to start driving the conveying device before the conveyed paper reaches the conveying device, and while the conveying device is being driven at a constant speed, the A means for controlling the transport of the material is provided.

With the above-described configuration, the stepping motor load connection method of the present invention adds a relatively simple mechanism to the connection means disposed between the stepping motor and the driven member. By providing this, it is possible to prevent problems such as step-out of the stepping motor from occurring. Further, in addition to the above-mentioned configuration, by additionally providing a control means for setting the drive start timing for the driven member earlier, it is possible to accurately control the paper conveyance speed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of connecting a load to a stepping motor according to the present invention will be explained with reference to the illustrated example. As shown in FIG. 1, the drive device 10 includes a connection device 1 disposed between a drive side motor 11 and a driven device 15, and a drive side member 2 of the connection device 1 on the driven side. The driving force is transmitted by engaging the member 5. In the example shown in FIG. 1, the motor 11 includes:
A stepping motor is used, and the driving pulses for the stepping motor are supplied to the motor driver circuit 12.
The driving device 15 is driven at a predetermined speed by starting the stepping motor at a low speed and gradually rotating it at a high speed. Further, the driven device 15 is configured to drive a drive shaft 18 connected to a driven member via gears 16 and 17.
Any means such as gears can be used as these transmission means.

In the connecting device 1 of the present invention, the relationship between the driving side member 2 and the driven side member 5 is configured as shown in FIG. In the connection device 1, the drive side member 2 is provided with a receiving groove 3 into which the claw member 6 of the driven side member 5 enters, and the side wall of the receiving groove 3 is set as a pressing surface 4. When the shaft is driven counterclockwise as shown by the arrow, the pressing surface 4 is pressed against the claw member 6 as shown in FIG.
, and transmits the rotational force of the motor to the driven member 5. Further, when the motor is rotated in the reverse direction (clockwise), the other side of the receiving groove 3 acts as a pressing surface.

In the connection device 1 of the present invention configured as described above, when the stepping motor is stopped,
The claw member 6 of the driven member 5 is connected to the receiving groove 3 of the driving member 2.
The driving of the stepping motor is controlled so that the stepping motor is stopped at the center of the stepping motor. and,
When starting a stepping motor, the stepping motor is started by applying an initial pulse of several to several tens of pulses to the stepping motor, and the stepping motor remains in a no-load state until it reaches a predetermined speed. and start driving the stepping motor in a state where it can start automatically. After the stepping motor is automatically activated, driving of the driven member 5 is started.

Therefore, in the connection device of the present invention, the stepping motor is started in a no-load state, and
By subsequently driving the driven device, it is possible to prevent step-out, etc., from occurring when starting the stepping motor.
The stepping motor can be driven in a normal state. In addition, in a device that drives a driven device by rotating a stepping motor in forward and reverse directions, the stepping motor is stopped and then driven in the opposite direction. If it is stopped, a large gap will be formed between it and the pressing surface on the other side during the next reverse drive. Therefore, when a pulse is applied to the stepping motor in the reverse direction to drive the stepping motor in the reverse direction, the self-starting action of the stepping motor can be easily performed.

The connection device of the present invention as described above is shown in FIG.
As shown in FIG. 2, the present invention can be applied to a registration roller 21 that conveys paper toward an image transfer section of an image forming apparatus. In the example shown in FIG. 4, the photoreceptor 25
The toner image formed on the transfer corotron 26 is transferred to a sheet of paper by discharge from the transfer corotron 26, and a sheet feeding means is provided immediately in front of the image transfer section. The paper feeding means is composed of a conveying roller 20 and a registration roller 21, and each roller device is composed of a driving roller and a pressing roller. In the registration roller 21, the drive device of the present invention is applied to the drive roller 22, and the drive roller 22 is driven using the connection device configured as shown in FIG.
The function is to feed the paper toward the image transfer section while nipping the paper between the two.

In the example shown in FIG. 4 of the present invention, the paper conveyed through the paper path is temporarily stopped with the leading edge of the paper nipped between the drive roller 22 and the pressure roller 23. Thereafter, the drive roller is rotated to perform a paper feeding operation in a state in which the timing is aligned with the toner image formed on the photoreceptor. At that time,
If the drive motor for the drive roller does not operate correctly,
A problem occurs where the paper feed speed is not set accurately. Therefore, in the present invention, the stepping motor is first started in a no-load state using the connecting device 1, and then the drive roller is driven. Therefore, the rotation of the drive roller is improved. This can be done in a safe condition.

Furthermore, in the apparatus of the present invention constructed as described above, for example, as shown in FIG.
When pressing the claw member 6 with the pressing surface 4 by arranging the
It can be configured to provide cushioning properties between both members. As described above, when the pressing surface of the driving side member exerts a pressing action on the pawl member 6 and is stopped, a gap is created between the pressing surface 4 and the pawl member 6 due to the elasticity of the elastic body 8. Let it form. Therefore, as described above, when an elastic body is interposed between them, an extra pulse is applied to the stepping motor after the drive is stopped to form a gap between the pressing surface and the claw member. Even without using such a control method, a gap is automatically formed between the two members.

Another embodiment of the present invention shown in FIG. 6 shows a case where the drive device of the present invention is applied to a conveyance roller in the paper path 30. In the example shown in FIG. 6, a sensor S is disposed in the paper path 30 upstream of the transport roller 32, and when the sensor S detects the paper, the drive for the transport roller 32 is started. The driving means is set. Conveyance roller 32 shown in the above embodiment
As shown in FIG. 7, a control device 13 is provided to input the detection signal from the sensor S, and output an operation signal to the motor driver circuit 12 based on the signal.

In the embodiment of the present invention, a control device of an image forming apparatus can be used as the control device 13, and a CP as a main controller can be used.
U can be provided with means for controlling paper feeding using a storage means such as a RAM or ROM, or a control program. Further, the conveyance roller device 32 is composed of a drive roller 33 driven by the drive device 10 and a pressure roller 34, as in the case of a general paper conveyance roller device, and the sheet is nipped between both rollers. In the state
It is designed to perform a conveying action.

[0022] Then, according to the signal from the control device 13,
The motor driver circuit 12 applies stepwise increasing drive pulses to the stepping motor to start driving the stepping motor. In this case, if the stepping motor 11 is in an unloaded state at the time of startup as shown in the above embodiment, the self-starting operation can be performed accurately, so that there is no disturbance in the rotational action. It performs the function of accurately rotating the conveyance roller without causing any damage.

Therefore, after the paper conveyed by the upstream conveyance roller 31 is detected by the sensor S, the conveyance roller 32 serving as the next conveyance means carries out the paper at a constant speed before the paper arrives. It is set to a state where the drive is being performed. Then, as described above, the transport roller 32 is nipped between the driving roller 33 of the conveying roller 32, which is driven at a constant speed, and the pressing roller 34, and is sent out at a constant speed toward the next process. become.

It should be noted that as the connection device for the conveyance roller shown in FIG. 7, any one having an arbitrary configuration among those shown in FIG. 2 or FIG. 5 can be used. Further, the self-starting means for a stepping motor of the present invention is not only applicable to the paper conveyance system as described above, but also to a method for driving a driven member at a constant speed using a stepping motor. It can be used as a means, and can be applied to any device that maintains the speed of each device constant, such as an image forming device.

[0025]

Effects of the Invention Since the stepping motor load connection method of the present invention uses the connection device having the above-described configuration, the connection means disposed between the stepping motor and the driven member is Just by adding and providing a relatively simple mechanism, the configuration does not become complicated. Furthermore, by using the connection device of the present invention, the stepping motor can be started automatically even when a load is applied to the driven side member, and problems such as step-out of the stepping motor can be prevented. , it is possible to accurately control the driving speed of the driven member. moreover,
For example, when applying the stepping motor load connection method of the present invention to a paper conveyance system of an image forming apparatus, before the paper reaches the conveyance roller etc.
By additionally providing a control means for setting the timing for starting the drive early, it is possible to accurately control the conveyance speed of the paper.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of a drive device of the present invention.

FIG. 2 is an explanatory diagram showing the configuration of a connection device of the present invention.

FIG. 3 is an explanatory diagram showing the relationship between the drive side member and the receiving groove in an operating state.

FIG. 4 is an explanatory diagram when the connecting device of the present invention is applied to a registration roller.

FIG. 5 is an explanatory diagram of another embodiment of the connection device of the present invention.

FIG. 6 is an explanatory diagram showing a case where the drive device of the present invention is applied to a paper conveyance path.

7 is an explanatory diagram of a drive device for the conveyance roller shown in FIG. 6. FIG.

FIG. 8 is a graph showing conditions for self-starting in a stepping motor.

[Symbols in the diagram]

1 Connection device 2 Drive side member 3 Receiving groove 5 Driven side member 6 Claw member 10 Drive device 11 Stepping motor 12 Motor driver circuit 13 Control device 15 Driven device

Claims (2)

[Claims] Claim 1. A driving device using a stepping motor having an excitation circuit and comprising a connecting means between an output shaft of the motor and an input shaft of a driven member, wherein there is a connection between the members constituting the connecting means. A method for connecting a load to a stepping motor, characterized in that both members are arranged with a margin set, and when the stepping motor is started, the stepping motor is driven without load and then the load is connected. 2. An apparatus for conveying paper using a driving device that uses a stepping motor having an excitation circuit and that is provided with connection means between the output shaft of the motor and the input shaft of the driven member, wherein the A control means is provided to start driving the conveyance device before the paper to be transported reaches the conveyance device, and the paper is controlled to be conveyed while the conveyance device is being driven at a constant speed. The method for connecting a load to a stepping motor according to claim 1.