JP2003237978A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device advantageous in a cost, and capable of enhancing working efficiency for treating jamming. <P>SOLUTION: This image forming device has a motor drive using a stepping motor 101 and supplying a current by a constant current chopper control system, as a driving source for a paper conveying system, has a chopping detecting means 201, a counting means 201 for counting a frequency of chopping, a comparison means 201 for comparing the frequency of the chopping with a reference frequency, a step-out detecting means 201 for judging step-out when the chopping frequency is judged to exceed the reference frequency by the comparison means 201, a first paper conveying roller 102 driven by the stepping motor 101, a second paper conveying roller 106 positioned in an upstream thereof, and a driving source 105 for driving the second paper conveying roller 106, and the driving of the second paper conveying roller 106 is stopped when the stepping motor 101 is judged to be stepped out. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus in which a motor, such as a stepping motor, which sequentially switches excitation phases to rotate and is controlled by a constant current chopper control system, is used as a drive source of a recording paper conveying system. It is a thing.

[0002]

2. Description of the Related Art In a conventional image forming apparatus such as a copying machine, a DC motor or the like is used as a drive source of a paper conveying system through which recording paper actually passes, and a paper is transferred via a transmission mechanism such as a gear or an electromagnetic clutch. A paper transport device that drives a plurality of transport rollers on a transport path has been widely used.

In this paper carrying device, the paper carrying control is realized by controlling the paper carrying roller by opening and closing the electromagnetic clutch.

In recent years, there has been an increasing need for high speed processing in image forming apparatuses, and as a result, higher speed of paper transportation in a paper transportation system has been increasingly demanded.

However, in the conventional paper conveyance control method in which the drive of the conveyance roller is turned on / off using an electromagnetic clutch or the like,
The response speed of the electromagnetic clutch is slow.

This has been a bottleneck in increasing the speed of paper conveyance.

On the other hand, stepping motors have come into wide use as driving sources for servo systems that are small and can be controlled in an open loop.

A stepping motor is a stepping motor in which the magnetic field rotates by sequentially switching the excitation phase current of the winding, and the magnetic pole of the rotor attracts and repels the rotating magnetic field to generate torque, which causes the rotor to generate a magnetic field. It is a motor that rotates while being dragged by.

Therefore, if the excitation phase is switched by inputting a pulse signal, the stepping motor rotates by a basic angle for one pulse input.

Therefore, in the stepping motor,
Open loop control is possible, and the system can be significantly simplified compared to other servo actuators that require a feedback system, which is advantageous in terms of cost.

In consideration of such an advantage, also in an image forming apparatus such as a copying machine, a stepping motor is used as a drive source of a paper conveying system for the number of conveying rollers, and the conveying rollers are driven without an electromagnetic clutch. Image forming apparatus.

[0012]

However, while the stepping motor can be made compact and inexpensive, unlike the conventional servo motor, it is different from the conventional servo motor in that it receives a pulse signal.
The phenomenon that the rotations of the rotor of the motor cannot be synchronized occurs.

This is called a step-out phenomenon.

In general, the step-out phenomenon occurs when the motor is in an overload state with respect to the pulse rate of the pulse commanded to the motor.

When a stepping motor is used in the paper carrying system of the image forming apparatus, if this step-out phenomenon occurs during the paper carrying, the paper carrying is stopped, which causes a new jam.

Further, in an image forming apparatus that conveys a plurality of papers, if the preceding paper is stopped due to a stepping motor step out, there is a possibility that the papers conveyed later may collide. there were.

The relationship between the step-out phenomenon and the jam will be described in more detail.

The stepping motor in the paper carrying system is activated before the paper reaches the paper carrying rollers.

In the paper conveying apparatus of the conventional image forming apparatus, even if a step-out phenomenon occurs before the paper arrives at the paper-conveying rollers, a jam is not immediately detected, but the paper is out-of-step. The paper arrives at the paper transport roller driven by the stepping motor that is causing the phenomenon, and the paper is not transported further from there, which is detected as a jam.

That is, if the step-out phenomenon is detected before the sheet arrives at the paper-conveying roller driven by the stepping motor causing the step-out phenomenon, and if this can be dealt with, a jam may occur. Can be prevented.

For example, in an image forming apparatus that conveys a plurality of paper sheets, even if the stepping motor that conveys the preceding paper sheet goes out of step and the paper feed roller stops, the step out is detected. If the conveyance of the paper conveyed by the roller located upstream of the roller can be stopped, the collision with the preceding paper can be avoided.

Further, in an image forming apparatus that conveys a plurality of papers, even if the stepping motor that conveys the preceding paper causes step out and the paper conveyance rollers stop,
If the motor can be restarted before the paper collision occurs and the previous paper transportation can be resumed normally, the paper transportation carried by the rollers located upstream can be returned to normal. This makes it possible to improve the processing efficiency of the image forming apparatus.

The step-out detection can be performed by attaching a sensor such as an encoder for detecting the rotation of the motor to the stepping motor or the like and monitoring the rotation of the motor.

However, if a sensor for detecting the rotation of the motor such as an encoder is attached, the system becomes complicated and the characteristic of the stepping motor cannot be utilized.

The present invention has been made in view of the above problems, and its object is to detect out-of-step of a stepping motor at high speed without a sensor, and to prevent a cause of jam from occurring. It is an object of the present invention to provide an image forming apparatus that is advantageous in terms of cost and can improve the work efficiency of jam processing by controlling the driving of the stepping motor.

[0026]

Therefore, in the present invention, the above object is achieved by providing an image forming apparatus shown in any one of the following items (1) to (10). Is.

(1) In an image forming apparatus, a stepping motor is used as a drive source of a paper conveying system, and a motor driving apparatus for supplying a current by a constant current chopper control system to sequentially switch the excitation phase of the stepping motor is provided. A chopping detecting means for holding and detecting that chopping has occurred, a counting means for counting the number of choppings in one cycle of the phase excitation signal by the chopping detecting means, a chopping number measured by the counting means, and preset. The stepping motor, a comparing means for comparing the reference number of times being performed, a step-out detecting means for determining that the stepping motor is out of step when the number of times of chopping measured by the comparing means exceeds the reference number of times. The driven first paper transport roller and the paper transport roller for the first paper transport roller. A stepping motor, which has a second paper transporting roller located upstream in the path and a drive source for driving the second paper transporting roller, and drives the first paper transporting roller is released by the step-out detecting means. An image forming apparatus, characterized in that the driving of the second paper carrying roller is stopped when it is determined that the adjustment has been made.

(2) In the image forming apparatus, a stepping motor is used as a drive source of the paper conveying system, and a motor driving device for supplying a current by a constant current chopper control system to sequentially switch the excitation phase of the stepping motor is provided. A chopping detecting means for holding and detecting that chopping has occurred, a counting means for counting the number of choppings in one cycle of the phase excitation signal by the chopping detecting means, a chopping number measured by the counting means, and preset. The stepping motor, a comparing means for comparing the reference number of times being performed, a step-out detecting means for determining that the stepping motor is out of step when the number of times of chopping measured by the comparing means exceeds the reference number of times. The driven first paper transport roller and the paper transport roller for the first paper transport roller. A stepping motor, which has a second paper transporting roller located upstream in the path and a drive source for driving the second paper transporting roller, and drives the first paper transporting roller is released by the step-out detecting means. An image forming apparatus characterized by decelerating the second paper transport roller when it is determined that the adjustment has been made.

(3) When it is determined that the stepping motor driving the first paper carrying roller is out of step, the current supply to the stepping motor is temporarily stopped, and after a certain time, the current to the stepping motor is stopped. The image forming apparatus as described in the item (1) or (2), wherein the supply is restarted and the stepping motor is restarted.

(4) When it is judged that the stepping motor driving the first paper carrying roller is out of step and the stepping motor is restarted and no step out phenomenon is detected, the stepping motor is stopped or decelerated. The image forming apparatus according to item (3), wherein control is performed to return the second paper transport roller to a predetermined drive.

(5) In the image forming apparatus, a stepping motor is used as a drive source of the paper conveying system, and a motor driving device for supplying a current by a constant current chopper control system to sequentially switch the excitation phase of the stepping motor is provided. A chopping detecting means for holding and detecting that chopping has occurred, a counting means for counting the number of choppings in one cycle of the phase excitation signal by the chopping detecting means, a chopping number measured by the counting means, and preset. Comparing means for comparing the number of times of chopping performed by the comparing means, and second counting means for counting the number of times the number of times of chopping measured by the comparing means has continuously exceeded the number of times of reference. A second comparing the measured number of times with a preset second reference number of times The stepping motor is driven by a comparing means, a step-out detecting means for determining that the step-out motor is out of step when the count value of the second counting means exceeds the second reference number by the second comparing means. A first paper carrying roller, a second paper carrying roller located upstream of the first paper carrying roller in the paper carrying path, and a drive source for driving the second paper carrying roller, 1. An image forming apparatus, which stops or decelerates the driving of the second paper carrying roller when the stepping motor driving the first paper carrying roller is out of step by the out-of-step detecting means.

(6) In the image forming apparatus, a plurality of stepping motors are used as the drive source of the paper conveying system, and the motor is driven by a constant current chopper control method to sequentially switch the excitation phases of the stepping motors. A current measuring means for measuring a value of a current flowing through the stepping motor in the motor drive device.
A timer device for measuring a preset time, a control device for issuing a measurement command to the current measuring device at predetermined time intervals preset by the timer device, and reading the obtained current value, and the current measuring device. Storage means for storing the current value measured by the means, current increase rate calculation means for calculating the current increase rate at a predetermined time interval, and current increase rate obtained by the current increase rate calculation means With a threshold value, a step-out detection unit that determines that a step-out has occurred when the current increase rate is larger than the threshold value by the comparison unit, and a first paper carrying roller driven by the stepping motor. A second paper transporting roller located upstream of the first paper transporting roller in the paper transporting path, and a drive source for driving the second paper transporting roller.
When it is determined by the step-out detecting means that the stepping motor driving the paper carrying roller is out of step, the second step is performed.
An image forming apparatus characterized in that driving of a paper carrying roller is stopped.

(7) In the image forming apparatus, a plurality of stepping motors are used as the drive source of the paper conveying system, and a motor is driven to supply a current by a constant current chopper control method to sequentially switch the excitation phases of the stepping motors. A current measuring means for measuring a value of a current flowing through the stepping motor in the motor drive device.
A timer device for measuring a preset time, a control device for issuing a measurement command to the current measuring device at predetermined time intervals preset by the timer device, and reading the obtained current value, and the current measuring device. Storage means for storing the current value measured by the means, current increase rate calculation means for calculating the current increase rate at a predetermined time interval, and current increase rate obtained by the current increase rate calculation means With a threshold value, a step-out detection unit that determines that a step-out has occurred when the current increase rate is larger than the threshold value by the comparison unit, and a first paper carrying roller driven by the stepping motor. A second paper transporting roller located upstream of the first paper transporting roller in the paper transporting path, and a drive source for driving the second paper transporting roller.
When it is determined by the step-out detecting means that the stepping motor driving the paper carrying roller is out of step, the second step is performed.
An image forming apparatus characterized by decelerating a paper carrying roller.

(8) When it is determined that the stepping motor driving the first paper carrying roller is out of step, the current supply to the stepping motor is temporarily stopped, and after a certain time, the current to the stepping motor is stopped. The image forming apparatus according to item (6) or (7), wherein the supply is restarted and the stepping motor is restarted.

(9) When it is judged that the stepping motor driving the first paper carrying roller is out of step and the stepping motor is restarted and no step out phenomenon is detected, the stepping motor is stopped or decelerated. The image forming apparatus according to the item (8), wherein control is performed to return the second paper transport roller to a predetermined drive.

(10) In the image forming apparatus, a plurality of stepping motors are used as drive sources for the paper transport system,
A motor driving device that supplies a current by a constant current chopper control method to sequentially switch the excitation phase of the stepping motor, and a current measuring unit for measuring a current value flowing in the stepping motor in the motor driving device, A timer device for measuring a preset time, a control device for issuing a measurement command to the current measuring device at predetermined time intervals preset by the timer device, and reading the obtained current value, and the current measuring device. Storage means for storing the current value measured by the means, current increase rate calculation means for calculating the current increase rate at a predetermined time interval, and current increase rate obtained by the current increase rate calculation means Is compared with a threshold value and the number of times the threshold value has been continuously exceeded in the past when the current increase rate is determined to be larger than the threshold value by the comparison means. And counting means for cement,
Second for comparing the number of times the current increase rate counted by the counting means exceeds the threshold value continuously with the reference number
The stepping motor is driven by a comparing means, a step-out detecting means characterized by the second comparing means for judging that a step-out has occurred when the number of times the current increase rate exceeds the threshold exceeds a reference number. The first paper carrying roller, and the first
A stepping motor having a second paper transporting roller located upstream of the paper transporting roller in the paper transporting path and a drive source for driving the second paper transporting roller, and driving the first paper transporting roller. An image forming apparatus, characterized in that, when the step-out detection unit determines that the step-out has occurred, the driving of the second paper carrying roller is stopped or decelerated.

That is, in order to achieve the above-mentioned object, in the image forming apparatus of the above item (1) having the motor drive device of the present invention, a constant current chopper is used as a motor that rotates by sequentially switching the excitation phase of a stepping motor or the like. A system that uses a motor drive unit that supplies a current by a control method, has a counting unit for counting the number of choppings, and counts the number of choppings of the drive unit within one cycle of the phase excitation signal.

As a feature of the stepping motor,
The number of times of chopping tends to increase at the time of step-out, as compared with the time of step-out and the time of driving according to the drive pulse, as compared with the time of normal rotation.

Therefore, in the invention of the above item (1), the number of choppings measured by the comparing means is compared with a preset reference number of times, and when the measured number of choppings exceeds the reference number of times, the motor is disconnected. The motor driving device is configured to generate a step-out signal by determining that there is a tuning phenomenon.

On the other hand, in the paper carrying path, the second paper carrying roller on the upstream side of the first paper carrying roller and another actuator for driving the second paper carrying roller are provided, and the first paper carrying roller is driven. When the step-out signal is received from the motor driving device for the stepping motor, the control for stopping the driving of the second paper carrying roller is performed.

In the image forming apparatus of the item (2), similarly, in the paper transport path, the second paper transport roller upstream of the first paper transport roller and another actuator for driving the second paper transport roller are provided. Therefore, when the step-out signal is received from the motor driving device of the stepping motor that drives the first paper transport roller, the control for decelerating the drive of the second paper transport roller is performed.

However, the chopping frequency of the motor drive circuit is a factor other than step-out, such as variation in characteristics of the stepping motor, increase in ambient temperature of the stepping motor body or the stepping motor, fluctuation of load of the stepping motor, and the like. But it is considered to fluctuate.

Therefore, in the invention of the above item (5), further, the second counting means for counting the number of times the chopping frequency continuously exceeds the reference number, and the number of times measured by the second counting means are set in advance. And a second comparing means for comparing the generated second reference number with the second comparing means. When the count value of the second counting means exceeds the second reference number when compared by the second comparing means, the motor is out of sync. The motor drive device is configured to generate a step-out signal.

Further, in the image forming apparatus of the present invention, in the motor drive device for driving the stepping motor which is the power source of the first paper conveying roller built in the image forming apparatus, the excitation phase of the stepping motor or the like is set. In an image forming apparatus that uses a motor drive unit that supplies current to a motor that sequentially switches and rotates by a constant current chopper control method, when the stepping motor is excited, the excitation pulse period measured by a timer device is sufficiently smaller than the excitation pulse period. The current value flowing through the motor is measured by the current detection means at short time intervals. The measured current value is accumulated in the storage means, and the current increase rate calculation means calculates the current increase rate from the current measurement time interval and the measured current value.

On the other hand, as a feature of the stepping motor,
When the step-out is compared with the case of driving according to the drive pulse, the increase rate of the current flowing through the motor coil tends to increase in the step-out, as compared with the case of normal rotation.

Therefore, in the invention of the above item (6), when the comparison means determines that the current increase rate is larger than the step-out detection reference current increase rate, it is determined that the stepping motor is out-of-step.

On the other hand, in the paper carrying path, the second paper carrying roller on the upstream side of the first paper carrying roller and another actuator for driving the second paper carrying roller are provided, and the first paper carrying roller is driven. When the step-out signal is received from the motor driving device for the stepping motor, the control for stopping the driving of the second paper carrying roller is performed.

In the image forming apparatus of the item (7), similarly, in the paper transport path, there is provided a second paper transport roller upstream of the first paper transport roller and another actuator for driving the second paper transport roller. Therefore, when a step-out signal is received from the motor driving device of the stepping motor that drives the first paper transport roller, control is performed to decelerate the drive of the second paper transport roller. There is.

However, the slope of the current response of the motor is a factor other than step-out, such as a variation in the characteristics of the stepping motor, an increase in the ambient temperature of the stepping motor itself or the stepping motor, or a change in the load of the stepping motor. But it is considered to fluctuate.

Therefore, in the invention of the above item (10),
The stepping motor is judged to be out-of-step if it has a counting means that counts the number of times the current increase rate continuously exceeds the step-out detection reference current increase rate. , By the step-out signal generating means,
It is configured to send out a step-out signal.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings.

(Embodiment 1) FIG. 1 is an internal configuration diagram of an embodiment to which the image forming apparatus of the present invention is applied.

Reference numeral 10 is a main body image output unit, 11 is a main body image input unit, 12 is an automatic document feeder, 13 is a sorter, 21 is a light source, 22, 23, 24 are mirrors, 25 is a lens, 26
Is a CCD, 27 is an optical irradiation unit, 28 is a scanner, 29 is a lens, 30 is a mirror, 31 is a photosensitive drum, 32 is a fixing roller, 33 is a paper discharge tray, 34 and 35 are paper feed trays,
36 is a paper feed deck, 37 is a manual feed tray, 38, 39,
Reference numerals 40, 41 and 42 denote paper conveying rollers.

This image forming apparatus has a main body image output section 10 which is an apparatus which puts and outputs a document image on a recording sheet, and a main body image input section 11 which is a device which reads image data from a document.
And an automatic document feeder 12 mounted on the upper portion of the main body image input section 11, and a sorter 13 for sorting and discharging the copy sheets discharged from the main body image output section 10 into a plurality of bins. .

This image forming apparatus is a digital copying machine, and when a manuscript is read, the image data of the manuscript is pixelated by the CCD of the main body image input section 11 which is a device for reading the image data from the manuscript, and the digital image data is read. After being read into the device as necessary and the necessary image processing has been performed,
Stored in image memory.

The image data is transferred to the main body image output section 10, the image is reproduced and copied on the recording paper.

The main body image input section 11 is a light source 21 for scanning while irradiating a document placed on a document table on the upper surface of the input section.
Equipped with.

The light source 21 is driven by an optical system motor (not shown) to reciprocate in the left-right direction in FIG.

The light emitted from the light source 21 is reflected by the loaded document to obtain an optical image.

The optical image is transmitted to the CCD 26 via the mirrors 22, 23, 24 and the lens 25.

At this time, the mirrors 22, 23 and 24 are driven integrally with the light source 21.

The CCD 26 is composed of an element for converting light into an electric signal, and the optical image transmitted by the function of this element is converted into an electric signal and further converted into a digital signal (image data).

The image data of the read document is subjected to various correction processes and image processes by the process desired by the user, and is stored in an image memory (not shown).

The main body image output section 10 reads out the image data stored in the image memory, reconverts the digital signal into an analog signal, and further amplifies it to an appropriate output value by an exposure control section (not shown) to perform optical irradiation. It is converted into an optical signal by the unit 27.

The optical signal is sent to the scanner 28 and the lens 29.
And, it propagates through the mirror 30 and is irradiated onto the photosensitive drum 31 to form a latent image by electrostatic.

This latent image forms an image with toner and is transferred onto a recording sheet conveyed in the main body. Further, the toner on the recording sheet is fixed by the fixing roller 32, image data is recorded, and the sorter 13 is provided. Sent to.

The sorter 13 is a device installed on the left side of the main body image output unit 10, and sorts the recording paper output from the main body image output unit 10 into the paper discharge tray 33 and discharges the paper. .

The paper discharge tray 33 is controlled by a main body controller (not shown), and the output recording paper is discharged to an arbitrary paper discharge tray designated by the main body controller (not shown).

The paper feed trays 34 and 35 are located at the bottom of the main body,
It is possible to store recording paper to some extent.

The main body controller (not shown) conveys the accumulated recording paper from the paper feed trays 34, 35 and outputs an image.

The paper feed deck 36 is a device installed on the right side of the main body image output section 10 and is capable of accumulating a large amount of recording paper.

Similar to the paper feed trays 34 and 35, the main body controller (not shown) conveys the accumulated recording paper and outputs an image.

On the right side of the main body image output section 10, there is provided a manual feed tray 37 which allows an operator to feed a small number of copy sheets of any type with relative ease.

The manual feed tray is also used when using special recording paper such as OHP sheets, thick paper, and postcard size paper.

Paper transport rollers 38, 39, 40, 41, 4
Each of the rollers 2 has a role of actually conveying the recording paper when the paper is fed in the copy output process.

The paper transport rollers 38, 39, 40, 41,
Each of 42 is independently connected to a stepping motor, which is a drive source, via a transmission device such as a gear.

Details of this portion are shown in FIG.

FIG. 2 is a detailed block diagram of the paper conveying device in the image processing apparatus of the present invention.

Reference numeral 101 denotes a stepping motor (Steppi) which is a drive source of a first paper carrying roller 102 which is a paper carrying device.
ng Motor), 102 is a first paper conveyance roller, 103 is a paper detection sensor, 104 is a photo interrupter which plays a role of converting a reaction of the paper detection sensor into an electric signal, and 105 is a second paper conveyance device which is a paper conveyance device. The stepping motor, which is the driving source of the roller 106, is the second
A paper transport roller.

Here, the arrow in the figure indicates the direction in which the paper is actually conveyed.

First, the stepping motor will be described.

A feature of the stepping motor is that it rotates according to the pulse power.

Moreover, since the rotation angle is changed in proportion to the number of input pulses and the rotation speed is changed in proportion to the input frequency, it is possible to drive the motor without forming a feedback loop.

Due to such characteristics, it is widely used as a drive source for open loop positioning control and speed control.

As a method of classifying stepping motors, classification based on motor structure is generally used.

For this, PM whose rotor part was made of a permanent magnet was used.
Type (Permanent Magnet Type), VR type (variable reluctance type) in which the rotor part is made of a gear-shaped iron core, and HR type (Hybrid T) in which the rotor part is made up of a gear-shaped iron core and a magnet
ype).

Another type of stepping motor is classified by the drive winding.

The drive windings are classified into two phases, three phases, five phases and the like.

The excitation mode can be classified into one-phase excitation, two-phase excitation and one-two-phase excitation.

In this embodiment, the first paper carrying roller 1
02, a two-phase excitation HR type stepping motor is used as a drive source for the second paper carrying roller 106.

Next, the structure of this embodiment will be described.

The first paper carrying roller 102 has a role of applying a force and carrying the recording paper to be actually carried.

The driving force from the stepping motor 101 is transmitted to the first sheet conveying roller 102 via a transmission device such as a gear, a shaft or a belt.

The second paper carrying roller 106 is located upstream of the first paper carrying roller as shown by the arrow.

The driving force from the stepping motor 105 is transmitted to the second paper carrying roller 106 via a transmission device such as a gear, a shaft, or a belt.

Although the paper passes in the direction indicated by the arrow in the figure, the paper detection sensor 103 is provided immediately after the paper carrying roller 106.
Is installed.

When the front end of the paper passes through the paper detection sensor 103, one end of the paper detection sensor 103 is pushed and the other end closes the space between the light emitting portion and the light receiving portion of the photo interrupter 104.

Paper detection sensor 103 and paper conveyance roller 102
Is shorter than the paper length of the smallest recording paper usable in the image forming apparatus, and if the stepping motor 101 operates normally and the paper carrying roller 102 is driven, the paper carrying roller 102 will move the paper. The paper detection sensor 103 is designed so that the paper is detected by the paper detection sensor 103 after a lapse of a certain time after the motor is driven after being conveyed.

When the light emitting portion and the light receiving portion of the photo interrupter 104 are blocked by the paper detection sensor 103, the output signal from the photo interrupter 104 changes.

The control unit of the image forming apparatus monitors the signal of the photo interrupter 104 at a constant interval, and if there is a change in the output signal, it judges that the paper is detected.

Next, referring to FIG. 3, the stepping motor used as the drive source of the paper conveying device of the image forming apparatus in this embodiment is incorporated in the image forming apparatus which is supplying power and controlling driving. The block diagram of a motor drive device is shown.

Reference numeral 201 denotes a chopping detecting means,
Counting means for counting the number of choppings, comparison means for comparing the measured number of choppings with a preset reference number, step-out detection means, second counting means, second comparison It is a central processing unit (hereinafter referred to as a CPU) that is a means and outputs a drive signal for the stepping motor 101.

Reference numeral 202 designates a drive circuit for supplying a current necessary for the rotation of the stepping motor 101, 203 designates a current sensor which is a current measuring means for measuring a current value, and 20
4 indicates the current value measured by the current sensor 203 in the CPU 20.
A / D converter for converting into a digital signal handled by 1.
205 is a timer which is a timer device for measuring a sufficiently short time, 206 is a ROM device in which a motor control program is stored, and 207 is a RAM device which is a storage unit used by the CPU 201 as a temporary storage area. Is.

The CPU 201, drive circuit 202, current sensor 203, AD converter 204, timer 205, ROM device 206, RAM device 207 constitute a motor drive device.

In the motor driving device, the CPU 201
Has a role of calling a stepping motor control program stored in the ROM device 206 and outputting a phase excitation signal, which is a drive signal of the stepping motor 101, to the drive circuit 202 in accordance with an instruction of the program.

That is, the phase excitation signal having a frequency corresponding to the target rotation speed of the motor is output.

Further, the CPU 201 has a timer 205 built-in, which can be called and used by a program, and is used for time measurement or for generating a specific interrupt process for each cycle.

Stepping motor 1 which is a feature of the present invention
The out-of-step detection process 01 is actually calculated by the CPU 201.

In the drive circuit 202, the constant current chopping control is constituted by hardware, and the current supplied to the stepping motor 101 is turned ON / OFF according to the phase excitation signal from the CPU 201, and the current flowing through the motor is a constant current. The chopping control is performed so that the current is supplied to the stepping motor 101.

A current sensor 203 for measuring the actual current value supplied to the stepping motor 101 is mounted on the drive circuit 202, and the current sensor 203 outputs a voltage proportional to the measured current.

The AD converter 204 converts the analog voltage output from the current sensor 203 into a digital signal, and outputs CP
Information on the current value being supplied to the motor is sent to U201.

The CPU 201 uses the stepping motor 10
The information from the current sensor 203 which is the actual current of 1 is AD
Observe through the converter 204.

In recent years, the AD converter 204 has been replaced by a CPU.
CPU 20 integrated in the same package as 201
1 is widely provided, and the CPU 201 having the built-in AD converter 204 is also used in this embodiment.

The ROM device 206 is a non-volatile storage device.

A motor control program is stored in the ROM device 206, and the program is stored in the CP as required.
It is loaded into U201.

The RAM device 207 is a rewritable storage device for storing the calculation result and temporarily saving the calculation result when the CPU 201 performs the calculation.

In recent years, the ROM device 206 and the RAM
There is also a CPU 201 in which the device 207 and the CPU 201 are integrated in the same package.
ROM device 206 and RAM device 207, if
Can be omitted.

Next, the characteristic difference between the actual current values when the stepping motor 101 normally rotates and when the stepping motor 101 is out of step is shown, and the means for detecting out-of-step from this characteristic will be described.

FIG. 4A is a graph showing the phase excitation signal and the current response when the stepping motor is rotating normally.

FIG. 4 (b) is a graph showing the phase excitation signal and the current response when step out occurs.

301 is a phase excitation signal supplied to the drive circuit 202, 302 is a current response when the stepping motor 101 is operating normally, and 303 is a current when the stepping motor 101 is out of step. It is a response.

When observing the graph 302 when the stepping motor 101 is rotating normally, the current supplied to the stepping motor 101 increases relatively slowly,
Therefore, it is understood that the frequency of chopping by the drive circuit 202 is relatively small.

On the other hand, when observing the graph 303 when the stepping motor 101 is out of step, the current supplied to the stepping motor 101 increases relatively rapidly.
Therefore, it is understood that the frequency of chopping by the drive circuit is relatively large.

From this, the stepping motor 101
It can be seen that the number of choppings performed by the drive circuit 202 tends to increase during step-out of the current supplied to the drive circuit, when compared with the normal state.

That is, when the stepping motor 101 is driven, this chopping frequency is constantly observed, and when the chopping frequency exceeds a certain reference frequency, it is predicted that a step-out has occurred, and a step-out signal is transmitted. It is possible to configure step-out detection means for the stepping motor 101.

However, the chopping frequency by the driving circuit 202 is a factor other than step-out, such as variation in characteristics of the stepping motor 101, increase in ambient temperature of the stepping motor 101 main body or the stepping motor 101, fluctuation of load of the stepping motor 101, etc. It is considered that the number of choppings also fluctuates due to the factor, and that the number of choppings that is larger than the reference number is intermittently observed.

Therefore, within a necessary and sufficient time, the drive circuit 20
When the number of times of chopping by 2 is larger than the reference number of times, that is, when the number of times of chopping is larger than the predetermined second reference number and continuously large, it is determined that the stepping motor 101 is out of step. Can also be

Next, the flow of actual processing of the step-out detection means will be described with reference to a flowchart.

FIG. 5 is a flow chart showing the counting process of the number of choppings necessary for the process of judging the out-of-step detection in this embodiment.

FIG. 6 is a flowchart showing the out-of-step detection process of this embodiment.

Here, CNT1 is the phase excitation signal HIGH.
CN, a variable that records the number of choppings in a level
T1f is a constant that stores the reference number of times for comparing with CNT1 to judge the out-of-step detection, CNT2 is a variable for recording the number of times that CNT1 continuously exceeded the value of CNT1f, and CNT2f is compared with CNT2. The constant MtrErr, which stores the reference number of times for determining the out-of-step detection, is a flag indicating that out-of-step of the stepping motor has been detected.

FIG. 5 is a flow chart showing the counting process of the number of choppings necessary for the process of judging the out-of-step detection of this embodiment.

The chopping number counting process is a process that is called during the motor rotation from the step-out detection process, monitors the chopping number by the constant current control of the driving device, and counts the number.

When the process is called, the process proceeds to step 1 (the step is represented by "S" in the figure).

In step 1, CNT1 which is a variable (hereinafter, also referred to as a counter) for counting the number of choppings is initialized to 0.

Then, the process proceeds to step 2.

In step 2, the state of the phase excitation signal is observed. If the phase excitation signal is HIGH level, the process proceeds to step 3. If it is LOW level, until the phase excitation signal becomes HIGH level. , Waiting process.

In step 3, the presence or absence of chopping is detected by the constant current control of the driving device.

If chopping occurs,
The process proceeds to step 4.

If chopping has not occurred, the process proceeds to step 5.

In step 4, the process of incrementing the value of CNT1 which is the counter of the number of choppings is performed, and the process proceeds to step 5.

In step 5, the state of the phase excitation signal is observed. If the phase excitation signal is HIGH level, the process proceeds to step 3, and if it is LOW level, the chopping frequency counting process is terminated.

In this way, in this embodiment, the number of choppings in one cycle of phase excitation is counted and the counter CNT is
The value is stored in 1.

Next, the step-out detection process, which is a feature of the present invention, will be described.

FIG. 6 is a flowchart showing the out-of-step detection process of this embodiment.

After the processing is started, the processing proceeds to step 11.

In step 11, processing is performed to determine whether the stepping motor is rotating.

If the motor is rotating, step 1
The process proceeds to 2.

If the drive control of the motor is stopped, the step-out detection process is terminated.

At step 12, processing for initializing the counters of CNT1 and CNT2 is performed.

After the initialization is completed, the process proceeds to step 13.

At step S13, a process for calling the chopping frequency counting process is performed.

As described with reference to the flowchart of FIG. 5, in the chopping number counting process, the number of choppings in one cycle of phase excitation is counted, the value is stored in CNT1, and the process returns.

After returning from the chopping frequency counting process, the process proceeds to step 14.

At step 14, the chopping count CN
The value of T1 is compared with the value of the constant CNT1f that stores the reference count, and if CNT1 is the constant CNT1 that stores the reference count.
If it exceeds f, the process proceeds to step 15.

If CNT1 is equal to or smaller than the constant CNT1f storing the reference number of times, the process proceeds to step 16.

In step 15, the value of the variable CNT2 for counting the number of times the CNT1 has continuously exceeded the constant CNT1f storing the reference number of times is incremented, and the process proceeds to step 17.

In step 16, the value of CNT2 is initialized.

After the initialization is completed, the process proceeds to step 19.

In step 17, a process of comparing the value of CNT2, which counts the number of times CNT1 successively exceeded the constant CNT1f storing the reference number, with the value of CNT2f, which is the constant storing the reference number, is executed. Is going.

If CNT2 is a constant C storing the reference number of times
If it exceeds NT2f, the process proceeds to step 18.

If CNT2 is equal to or smaller than the constant CNT2f storing the reference number of times, the process proceeds to step 19.

At step 18, it is determined that the stepping motor is out of step, and MtrErr is set to 1 to notify the stepping motor of step out.

After that, the step-out detection processing is ended.

In step 19, processing is performed to determine whether the stepping motor is rotating.

If the motor is rotating, step 1
Proceed to step 3 until the motor drive is stopped,
Then, the step-out detection process is performed.

If the drive control of the motor is stopped, the step-out detection processing is ended.

Next, the stop processing of the second paper carrying roller will be described with reference to FIG.

This processing is always executed when the paper is being conveyed in the image forming apparatus.

This process is repeatedly executed between Loop and Loop_End when the paper conveyance process is being performed by the image forming apparatus.

At step 101, the value of the variable MtrErr is read to determine whether or not the stepping motor 101 driving the first paper carrying roller 102 is out of step.

If the stepping motor 101 is out of step, 1 is written in MtrErr (see step 18 in FIG. 6).

If 1 is written in MtrErr, the process proceeds to step 102.

If 0 is written in MtrErr, the process proceeds to Loop_End, returns to Loop, and is repeated until the paper carrying process is completed.

At step 102, the driving status of the stepping motor 105 driving the second paper carrying roller 106 is judged.

If the stepping motor 105 is not driven, the process proceeds to step 103.

If the stepping motor 105 is driven, the process proceeds to step 104.

In step 103, the stepping motor 101 driving the first paper carrying roller 102 is out of step and the stepping motor 105 driving the second paper carrying roller 106 is not driven. 2 Stepping motor 1 which is a drive source of the paper transport roller 106
05 is prohibited.

After the processing of this step is completed, the processing for stopping the second paper carrying roller is completed.

In step 104, the stepping motor 101 driving the first paper carrying roller 102 is out of step, and the stepping motor 105 driving the second paper carrying roller 106 is driving. The process of stopping the driving of the stepping motor 105, which is the drive source of the second paper carrying roller 106, is performed.

After the processing of this step is completed, the processing for stopping the second paper carrying roller is completed.

As described above, in this embodiment, when it is determined that the stepping motor 101 is out of step with the first paper carrying roller 102 using the stepping motor 101 as a driving source for paper carrying, the upstream side Motor 105 driving the second paper transport roller 106 at
It is configured to perform control for stopping.

(Embodiment 2) Next, in Embodiment 2, the stepping motor 10 which drives the first paper carrying roller 102.
When it is determined by the step-out detection means that step 1 has failed, the second step
An image forming apparatus that decelerates the paper carrying roller 106 will be described.

In the second embodiment, the main body configuration of the image forming apparatus, the step-out detection method of the stepping motor, and the like are the same as those in the first embodiment, and therefore the description thereof is omitted.

With reference to FIG. 8, the procedure of the motor deceleration process for the second paper carrying roller in the present embodiment when the stepping motor driving the first paper carrying roller is out of step will be described.

This processing is always executed when the paper is being conveyed in the image forming apparatus.

Here, the variable MtrFlag is a variable indicating the state of the stepping motor 105 driving the second paper carrying roller 106.

In step 151, the value of the variable MtrErr is read to determine whether or not the stepping motor 101 driving the first paper carrying roller 102 is out of step.

If the stepping motor 101 is out of step, 1 is written in MtrErr (FIG. 6, FIG.
See step 18).

If 1 is written in the variable MtrErr, the process proceeds to step 152.

If 0 is written in MtrErr, the process proceeds to step 153.

At step 152, the drive status of the stepping motor 105 driving the second paper carrying roller 106 is determined.

If the stepping motor 105 is not driven, the process proceeds to Loop_End and this process is repeated.

If the stepping motor 105 is driven, the process proceeds to step 154.

At step 154, the stepping motor 101 driving the first paper carrying roller 102 is out of step, and the stepping motor 105 driving the second paper carrying roller 106 is driving. The process of decelerating the drive of the stepping motor 105, which is the drive source of the second paper carrying roller 106, to a predetermined speed is performed.

After the motor deceleration process is completed, the process proceeds to step 155.

At step 155, the variable MtrFlag is set.
The process of writing 1 indicating that the motor is in the deceleration state is performed.

After step 155, Loop_End
Go to and repeat this process.

In step 153, it is determined whether the value of the variable MtrFlag is 1.

If 1 is written, the process proceeds to step 156.

If 0 is written, it means that the motor is operating normally or is stopped. Therefore, the process proceeds to Loop_End and this process is repeated.

At step 156, the first paper carrying roller 1
Although the stepping motor 101 driving 02 is operating normally, the stepping motor 105 still driving the second paper carrying roller 106 is operating at a reduced speed. The process of accelerating until it becomes (predetermined drive) is called.

After the end, the process proceeds to step 157.

At step 157, since the operation of the stepping motor 105 driving the second paper carrying roller 106 has recovered from the decelerating operation to the normal operation, the process of clearing the value of the variable MtrFlag indicating the motor state to 0 is executed. Is going.

After step 157 is completed, Loop_
The process proceeds to End and this process is repeated.

Next, the stepping motor restart process in the paper carrying device will be described with reference to FIG.

The operation of this process starts after the step-out is detected.

In step 201, the process of stopping the current supply to the stepping motor which is out of step is performed.

[0209] After the processing is completed, the process proceeds to step 202.

In step 202, a timer Wait process for waiting a predetermined time is carried out in order to remove the back electromotive force accumulated in the coil of the stepping motor which has been excited.

After the processing, the processing proceeds to step 203.

At step 203, the stepping motor is restarted.

After the normal activation, the processing is terminated.

If the step-out detection processing is started again after this restart processing and the stepping motor 101 is operating normally, the variable MtrErr is cleared to 0, and as described in S151 of FIG. Therefore, it is determined that the variable MtrErr is not 1, and the stepping motor 105 that was driving the second paper transport roller 106 resumes normal driving.

(Third Embodiment) Next, a case will be described in which a method of detecting a step-out in the third embodiment is a method of detecting by a slope of a current response.

The main body structure of the image forming apparatus is almost the same as that of the first and second embodiments described above, and the description thereof will be omitted.

However, 201 is a control means, a current increase rate calculation means, a comparison means for comparing the current increase rate with a threshold value, and a step-out detection means, and it is assumed that the current increase rate is larger than the threshold value. CPU, which is a counting means for counting the number of times the threshold value has continuously exceeded the threshold in the past, and a second comparison means for comparing the number of times the current increase rate has continuously exceeded the threshold value with a reference number. Is.

First, the characteristic difference between the actual current value when the stepping motor 101 is normally rotating and when the stepping motor 101 is out of step is shown, and the means for detecting out-of-step from this characteristic will be described.

The description will be made again with reference to FIGS. 4 (a) and 4 (b).

When observing the graph 302 when the stepping motor 101 normally rotates, it can be seen that the current supplied to the stepping motor 101 increases relatively moderately.

On the other hand, when observing the graph 303 when the stepping motor 101 is out of step, it can be seen that the current supplied to the stepping motor 101 increases relatively rapidly.

From this, the stepping motor 101
It can be seen that the current supplied to the motor tends to have a larger slope of current response during step out than during normal operation.

That is, when the stepping motor 101 is driven, the slope of this current response is always observed, and when the slope becomes larger than a certain threshold, it is predicted that a step-out has occurred, and a step-out signal is transmitted. , Stepping motor 1
01 out-of-step detection means can be configured.

However, the slope of the current response is a factor other than step-out, such as variations in the characteristics of the stepping motor 101, an increase in the ambient temperature of the stepping motor 101 or the stepping motor 101, fluctuations in the load of the stepping motor 101, etc. It is considered that the fluctuations may also occur due to the factor, and it is considered that the slope of the current response larger than the threshold value is intermittently observed.

Therefore, when the slope of the current response is larger than the threshold within a necessary and sufficient time, that is, when the current response is continuously measured larger than the predetermined reference number of times and larger than the threshold, the stepping motor 101 is operated. Can be determined to be out of sync.

Next, the flow of actual processing of the step-out detection means will be described with reference to a flowchart.

FIG. 10 is a flow chart for making a decision to call the step-out detection processing in this embodiment.

FIG. 11 is a flow chart showing the process of judging the out-of-step detection of this embodiment.

Here, dT is the step-out detection processing interval (time interval), It is the current value of the current supplied to the stepping motor, Itb is the current value at the time dT before the present, and dI is the measured value. The current increase rate, dIf is a threshold value of the current increase rate for judging out-of-step detection, CNT is a variable for recording the number of times the measured current increase rate dI continuously exceeds the threshold value dIf, and CNTf is out-of-step. CN for judging detection
The threshold value of the T value, MtrErr, is a flag indicating that the stepping motor is out of step.

The judgment to call the step-out detection process is called at the timing of "HIGH" level in the cycle of the phase excitation signal, and the process starts.

After this processing is started, step 1001
(The step is indicated by "S" in the figure).

At step 1001, it is judged whether or not the phase excitation signal is at "HIGH" level. If the phase excitation signal is at "HIGH" level, the process proceeds to step 1002, where the phase excitation signal is If it is the “LOW” level, this process is terminated.

At step 1002, a process for starting a timer for measuring the timing for carrying out the step-out detection process is performed.

After the timer is started, the process proceeds to step 1003.

In step 1003, the current value currently supplied to the stepping motor 101 is set to the drive circuit 202.
The value measured by the current sensor 203 inside is AD converted,
The process of reading into the CPU 201 is being performed.

After reading the AD value, the process proceeds to step 1004.

In step 1004, step 1003
Then, the AD value read into the CPU 201 is stored in the variable If, and the process proceeds to step 1005.

In step 1005, step 1002
The timer value started in step 2 is compared with the step-out detection processing interval dT, and a process of waiting until the timer value matches dT is performed.

When the timer value matches dT, step 1
The process proceeds to 006.

In step 1006, the step-out detection processing is called (see FIG. 11).

Next, the step-out detection processing will be described with reference to FIG.

In step 1006 of FIG. 10, the process is called to start the step-out detection process.

After the processing is started, the processing is advanced to step 1101.

At step 1101, it is determined whether or not the stepping motor 101 is rotating, that is, the CPU 201.
Determines whether the phase excitation signal is generated.

If the phase excitation signal is not output,
If the step-out detection process is completed and the phase excitation signal is output, the process proceeds to step 1102.

If the stepping motor 101 is rotating, in step 1102, the value of the current value It supplied to the stepping motor 101 read in the previous processing is set to I.
It is saved at tb and the process proceeds to step 1103.

In step 1103, the current value currently supplied to the stepping motor 101 is set to the drive circuit 202.
The value measured by the current sensor 203 inside is AD converted,
The process of reading into the CPU 201 is being performed.

After reading the AD value, the process proceeds to step 1104.

In step 1104, step 1103
Then, the AD value read into the CPU 201 is stored in the variable It, and the process proceeds to step 1105.

In step 1105, step 1103
The difference between the current value It, which was read in step d, and the value itb, in which the current value that was measured and read before dT time was stored, was taken and the value was divided by dT, which is the current measurement cycle.
The calculation to be stored in I is performed.

The dI calculated here is the current increase rate of the stepping motor.

Next, the process proceeds to step 1106.

In step 1106, step 1105
The value of the increase rate dI of the supply current to the stepping motor 101 calculated in step 3 is compared with the value dIf which is the threshold value of the current increase rate.

If the value of dI is larger than the threshold value dIf, the process proceeds to step 1107.

If the value of dI is less than or equal to the threshold value dI, the stepping motor is not judged to be out of step, and the process proceeds to step 1108.

At step 1107, since the current current increase rate dI exceeds the threshold value dIf, the value of the counter CNT is incremented, and the process proceeds to step 1109.

At step 1108, since the current value of the current increase rate dI is less than or equal to the threshold value dIf, the counter CN
The process of initializing the value of T to 0 is performed, and the step-out detection process is ended.

At step 1109, the counter CNT which records the number of times the current increase rate dI continuously exceeds the threshold value dIf and the counter threshold value CN for the step-out determination.
The value is compared with Tf.

If CNT is larger than CNTf,
It is determined that the stepping motor is out of step, and the process proceeds to step 1110.

If CNT is equal to or less than CNTf, it is not determined at this time that the step is out of step, and the process proceeds to step 1102.

At step 1110, it is judged that the stepping motor 101 is out of step, and the variable MtrErr is set to 1
The stepping motor 101 is written to perform step (transmitting) indicating that the stepping motor 101 is in the step-out phenomenon.

After that, the step-out detection processing is ended.

Since the processing after detecting the step-out is the same as the processing shown in the first and second embodiments, detailed description will be omitted.

That is, when it is determined by the step-out detecting means that the stepping motor 101 driving the first paper carrying roller 102 is out of step due to the inclination of the current response,
The second paper carrying roller 106 may be stopped as in the first embodiment or may be decelerated as in the second embodiment.

[0265]

As described above, according to the present invention, the chopping frequency measuring means and the chopping frequency measuring means measure in the motor control device for driving the stepping motor incorporated in the image forming apparatus. When the measured chopping frequency exceeds the reference frequency, the motor is out of sync with the comparison means for comparing the chopping frequency with the preset reference frequency. Therefore, it is possible to provide the image forming apparatus capable of detecting the step-out only by the motor driving device built in the image forming apparatus.

Further, in the paper transport path, a first paper transport roller driven by a stepping motor driven by a motor driving device having a step-out detection means, and a second paper transport upstream of the first paper transport roller. If a control device that controls the second paper transport roller receives a step-out detection signal from a motor drive device that has a roller and that drives the first paper transport roller, the control device controls the second Even if the stepping motor causes a step-out phenomenon, the recording paper being conveyed is stopped or decelerated on the side of the second paper conveyance roller even if the stepping motor causes a step-out phenomenon by controlling the paper conveyance roller drive to stop or decelerate. As a result, it is possible to prevent the recording paper from being damaged, and it is possible to provide an image forming apparatus capable of improving the work efficiency of the jam processing by the operator.

Further, even when the stepping motor causes a step-out phenomenon in a state where there is no paper on the first paper carrying roller, by stopping or decelerating the recording paper on the second paper carrying roller side, It is possible to provide time for restarting the stepping motor, and as a result, it is possible to avoid occurrence of a jam, and it is possible to provide an image forming apparatus capable of improving the copy work efficiency.

Further, when the number of choppings by the motor driving device continuously exceeds the first reference number of times over the preset reference number of times, it is determined that the step is out of step. When the number of times of chopping by the motor drive circuit temporarily exceeds the first reference number, it is possible to exclude from the step-out determination, and it is possible to provide an image forming apparatus capable of detecting the step-out phenomenon with high accuracy. Becomes

Further, in the motor control device for driving the stepping motor incorporated in the image forming apparatus,
Only the motor drive unit built into the image forming apparatus has a step-out detection unit that measures the current increase rate of the current supplied to the motor and determines that the stepping motor has stepped out when the current increase rate exceeds a threshold value. It is possible to provide an image forming apparatus capable of detecting out-of-step.

Further, in the paper transport path, a first paper transport roller powered by a stepping motor driven by a motor driving device having a step-out detection means, and a second paper transport upstream of the first paper transport roller. If a control device that controls the second paper transport roller receives a step-out detection signal from a motor drive device that has a roller and that drives the first paper transport roller, the control device controls the second Even if the stepping motor causes a step-out phenomenon, the recording paper being conveyed is stopped or decelerated on the side of the second paper conveyance roller even if the stepping motor causes a step-out phenomenon by controlling the paper conveyance roller drive to stop or decelerate. As a result, it is possible to prevent the recording paper from being damaged, and it is possible to provide an image forming apparatus capable of improving the work efficiency of the jam processing by the operator.

Further, even when the stepping motor causes a step-out phenomenon when there is no paper on the first paper carrying roller, by stopping or decelerating the recording paper on the side of the second paper carrying roller, It is possible to provide time for restarting the stepping motor, and as a result, it is possible to avoid occurrence of a jam, and it is possible to provide an image forming apparatus capable of improving the copy work efficiency.

Furthermore, when the current increase rate exceeds the threshold value continuously for a preset number of times or more, it is determined that the step is out of step. In case of temporarily exceeding, it is possible to exclude from the step-out determination, and it is possible to provide the image forming apparatus capable of detecting the step-out phenomenon with high accuracy.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment to which an image processing apparatus of the present invention is applied.

FIG. 2 is a detailed configuration diagram of a paper transport device in the image processing apparatus of the present invention.

FIG. 3 is a configuration diagram of a motor driving device incorporated in an image forming apparatus that supplies power and controls driving to a stepping motor used as a drive source of a sheet conveying device of the image forming apparatus of the present invention. is there.

FIG. 4 is a diagram for explaining a criterion for detecting a step out of a stepping motor.

FIG. 5 is a flowchart showing a counting process of the number of choppings necessary for the process of determining the out-of-step detection in the first embodiment.

FIG. 6 is a flowchart showing a step-out detection process of the first embodiment.

FIG. 7 is a flowchart showing a procedure of a motor stop process of a second paper carrying roller when a stepping motor driving a first paper carrying roller is out of step in the first embodiment.

FIG. 8 is a flowchart showing a procedure of a motor deceleration process for a second paper carrying roller when a stepping motor driving a first paper carrying roller is out of step in the second embodiment.

FIG. 9 is a flowchart showing a procedure of stepping motor restart processing in the second embodiment.

FIG. 10 is a flowchart showing a procedure of a task of monitoring an excitation signal and calling a step-out detection process in the third embodiment.

FIG. 11 is a flowchart illustrating a procedure of step-out detection processing according to the third embodiment.

[Explanation of symbols]

101 stepping motor 102 first paper transport roller 105 stepping motor 106 first paper transport roller 201 CPU 202 drive circuit 203 Current sensor 204 AD converter 205 timer 206 ROM device 207 RAM device

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Claims (10)

[Claims] In an image forming apparatus, a stepping motor is used as a drive source of a paper conveying system, and a motor driving device that supplies a current by a constant current chopper control method to sequentially switch excitation phases of the stepping motor is provided. ,
Chopping detection means for detecting the occurrence of chopping, and the phase excitation signal 1 by the chopping detection means.
Counting means for counting the number of choppings in a cycle, comparing means for comparing the number of choppings measured by the counting means with a preset reference number, and the number of choppings measured by the comparing means is a reference Step-out detection means for determining step-out when the number of times is exceeded, a first paper carrying roller driven by the stepping motor, and an upstream side of the first paper carrying roller in the paper carrying path. That the stepping motor driving the first paper transport roller has a step out by the step-out detection means. An image forming apparatus, characterized in that when the determination is made, the driving of the second paper carrying roller is stopped. 2. An image forming apparatus, wherein a stepping motor is used as a drive source of a paper conveying system, and a motor driving device for supplying a current by a constant current chopper control method for sequentially switching excitation phases of the stepping motor is provided. ,
Chopping detection means for detecting the occurrence of chopping, and the phase excitation signal 1 by the chopping detection means.
Counting means for counting the number of choppings in a cycle, comparing means for comparing the number of choppings measured by the counting means with a preset reference number, and the number of choppings measured by the comparing means is a reference Step-out detection means for determining step-out when the number of times is exceeded, a first paper carrying roller driven by the stepping motor, and an upstream side of the first paper carrying roller in the paper carrying path. That the stepping motor driving the first paper transport roller has a step out by the step-out detection means. An image forming apparatus characterized in that when the determination is made, the second paper transport roller is decelerated. 3. When it is determined that the stepping motor driving the first paper carrying roller is out of step, the current supply to the stepping motor is temporarily stopped, and after a certain time, the current supply to the stepping motor is supplied. Resume,
The image forming apparatus according to claim 1, wherein the stepping motor is restarted. 4. When the stepping motor driving the first paper carrying roller is judged to be out of step and the stepping motor is restarted and no step out phenomenon is detected, the stepping motor is stopped or decelerated. The image forming apparatus according to claim 3, wherein control is performed to return the second paper transport roller to a predetermined drive. 5. An image forming apparatus, comprising a stepping motor as a drive source of a paper carrying system, and having a motor driving device for supplying a current by a constant current chopper control method to sequentially switch excitation phases of the stepping motor. ,
Chopping detection means for detecting the occurrence of chopping, and the phase excitation signal 1 by the chopping detection means.
Counting means for counting the number of choppings in a cycle, comparing means for comparing the number of choppings measured by the counting means with a preset reference number, and the number of choppings measured by the comparing means is a reference Second counting means for counting the number of times that the number of times has been exceeded in succession; second comparing means for comparing the number of times measured by the second counting means with a preset second reference number; (2) Out-of-step detecting means for determining that the step has been out of step when the count value of the second counting means exceeds the second reference number by the comparing means, and the first paper conveyance driven by the stepping motor. A roller, a second paper carrying roller located upstream of the first paper carrying roller in the paper carrying path, and a driving device for driving the second paper carrying roller. And stopping the driving of the second paper carrying roller when the stepping motor driving the first paper carrying roller has a power source An image forming apparatus characterized by. 6. An image forming apparatus, wherein a plurality of stepping motors are used as a drive source of a paper carrying system, and a motor driving apparatus which supplies a current by a constant current chopper control method for sequentially switching excitation phases of the stepping motors. And a current measuring means for measuring a current value flowing in the stepping motor in the motor drive device, a timer device for measuring a preset time, and a predetermined time preset by the timer device. Control means for issuing a measurement command to the current measuring means at intervals and reading the obtained current value, storage means for storing the current value measured by the current measuring means, and increase of the current at predetermined time intervals A current increase rate calculation means for calculating the rate, a comparison means for comparing the current increase rate obtained by the current increase rate calculation means with a threshold value, A step-out detection unit that determines that a step-out has occurred when the current increase rate is larger than a threshold value by the comparison unit, and a first stepping motor that is driven by the stepping motor.
A paper carrying roller, a second paper carrying roller located upstream of the first paper carrying roller in the paper carrying path, and a second paper carrying roller
When the stepping motor, which has a drive source for driving the paper carrying roller and drives the first paper carrying roller, is out of step by the out-of-step detecting means, the second paper carrying roller is driven. An image forming apparatus characterized in that the image forming apparatus is stopped. 7. An image forming apparatus, wherein a plurality of stepping motors are used as a drive source of a paper conveying system, and a motor driving apparatus supplies a current by a constant current chopper control method to sequentially switch excitation phases of the stepping motors. And a current measuring means for measuring a current value flowing in the stepping motor in the motor drive device, a timer device for measuring a preset time, and a predetermined time preset by the timer device. Control means for issuing a measurement command to the current measuring means at intervals and reading the obtained current value, storage means for storing the current value measured by the current measuring means, and increase of the current at predetermined time intervals A current increase rate calculation means for calculating the rate, a comparison means for comparing the current increase rate obtained by the current increase rate calculation means with a threshold value, A step-out detection unit that determines that a step-out has occurred when the current increase rate is larger than a threshold value by the comparison unit, and a first stepping motor that is driven by the stepping motor.
A paper carrying roller, a second paper carrying roller located upstream of the first paper carrying roller in the paper carrying path, and a second paper carrying roller
When the stepping motor, which has a drive source for driving the paper carrying roller and drives the first paper carrying roller, is out of step by the out-of-step detecting means, decelerates the second paper carrying roller. An image forming apparatus comprising: 8. When it is determined that the stepping motor driving the first paper carrying roller is out of step, the current supply to the stepping motor is temporarily stopped, and after a certain period of time, the current supply to the stepping motor is supplied. Resume,
The image forming apparatus according to claim 6, wherein the stepping motor is restarted. 9. When the stepping motor driving the first paper carrying roller is judged to be out of step and the stepping motor is restarted and no step out phenomenon is detected, the stepping motor is stopped or decelerated. The image forming apparatus according to claim 8, wherein control is performed to return the second paper transport roller to a predetermined drive. 10. An image forming apparatus, wherein a plurality of stepping motors are used as a drive source of a paper conveying system, and a motor driving apparatus which supplies a current by a constant current chopper control method for sequentially switching excitation phases of the stepping motors. And a current measuring means for measuring a current value flowing in the stepping motor in the motor drive device, a timer device for measuring a preset time, and a predetermined time preset by the timer device. Control means for issuing a measurement command to the current measuring means at intervals and reading the obtained current value, storage means for storing the current value measured by the current measuring means, and increase of the current at predetermined time intervals A current increase rate calculating means for calculating the rate, and a comparing means for comparing the current increase rate obtained by the current increase rate calculating means with a threshold value. If the current increasing rate is larger than the threshold value by the comparing means, a counting means for counting the number of times the threshold value has been continuously exceeded in the past, and the current increasing rate counted by the counting means continuously keeps the threshold value. And a second comparing means for comparing the number of times the number of times exceeds the reference number and the number of times that the current increase rate exceeds the threshold value by the second comparing means. Characteristic step-out detection means, a first paper carrying roller driven by the stepping motor, a second paper carrying roller located upstream of the first paper carrying roller in a paper carrying path, and the second paper carrying roller. When the stepping motor, which has a drive source for driving the paper carrying roller and drives the first paper carrying roller, is out of step by the out-of-step detecting means, the second paper carrying roller is driven. To An image forming apparatus characterized by stopping or decelerating.