JP2000253696A - Stepping motor controller, image recorder, and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need for using an unnecessarily large and expensive stepping motor, by enabling a stepping motor used as a recording material feed means in an electronic photograph system of image recorder to be controlled properly. SOLUTION: Stepping motors M1 and M2 for carrying recording material are driven by each drive circuit IC1 and IC2. At that time, excitation phase signals are generated with phase signal generating circuits IC3 and IC4 by the motor clock from a sequence controller, and they are outputted to each drive circuit IC1 and IC2, and the excitation currents of the stepping motors M1 and M2 are switched by an image formation process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor control apparatus, an electrophotographic image recording apparatus for feeding a recording material using a stepping motor, and a control method therefor.

[0002]

2. Description of the Related Art In an electrophotographic image recording apparatus, for example, a color copying machine having a transfer drum, it is necessary to continuously and stably convey a recording material to a predetermined position on the transfer drum during image formation. Up to the transfer drum, it must be transported at a speed higher than the image forming speed,
Variable speed feed control is being performed. In order to realize such a shift feeding control, a stepping motor is conventionally used as a driving motor of a recording material feeding unit. This makes it possible to stably feed the recording material with a simple configuration.

[0003]

In the case where the stepping motor is used as the recording material feeding means as described above, it is easy to simplify the structure of the drive system while realizing various shift controls, and the It is easy to obtain the accuracy of the sending position or time.

However, since a stepping motor is generally under open-loop control, if the load torque fluctuation exceeds the output of the motor, the motor loses synchronism and causes a paper jam in a recording apparatus. In order to prevent this, it is necessary to provide a margin for the drive current of the motor and to secure a sufficient torque, but it cannot be blindly increased due to the self-heating of the motor and the cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the load torque required for a stepping motor for each material and other control modes is described.
Focusing on the difference in drive speed and drive duty, it is possible to suppress the self-heating of the stepping motor while satisfying the required drive torque, and configure the device without using unnecessary and expensive equipment. It is an object of the present invention to provide a stepping motor control device, an image recording device, and a control method therefor that can perform the control.

[0006]

According to the present invention, there is provided a stepping motor control apparatus, an image recording apparatus and a control method thereof.
It is configured as follows.

(1) In a control device for controlling the driving of the stepping motor, switching means for switching the exciting current of the stepping motor is provided, and the exciting current is switched according to the driving mode of the stepping motor.

(2) An electrophotographic image recording apparatus, comprising: a feeding means for feeding a recording material using a stepping motor; and a switching means for switching an exciting current of the stepping motor. The recording material is fed by switching the excitation current of the stepping motor by an image forming process according to the type of the recording material.

(3) In the configuration of the above (2), a plurality of stepping motors of the feeding means are provided, and the exciting current of each stepping motor is switched.

(4) In the above configuration (2) or (3), the stepping motor is not excited when the recording material is not fed.

(5) In any one of the constitutions (2) to (4), a feeding means for feeding the recording material from the storage portion for the recording material and an arbitrary recording material from the manual paper feeding portion. The image forming apparatus includes a feeding unit and a feeding unit that drives a conveyance unit through which the recording material passes to feed the recording material.

(6) A method for controlling an electrophotographic image recording apparatus, wherein a recording material is fed by using a stepping motor, and the exciting current of the stepping motor is changed to form an image according to the type of recording material. The recording material is fed by switching according to the process.

(7) In the above configuration (6), the stepping motor is not excited when the recording material is not fed.

[0014]

FIG. 1 is a sectional view showing the structure of an image recording apparatus according to the present invention. Here, the entire structure of an electrophotographic digital color copying machine is shown.

[Overall Configuration] This embodiment has a digital color image reader section at the top and a digital color image printer section at the bottom.

In the reader section, the original 30 is placed on an original platen glass 31 and is exposed and scanned by an exposure lamp 32 so that a reflected light image from the original 30 is condensed on a full-color sensor 34 by a lens 33 to form a color image. Obtain a decomposed image signal. The color-separated image signal is processed by a video processing unit (not shown) through an amplification circuit (not shown), and is sent to a printer unit.

In the printer section, a photosensitive drum 1, which is an image carrier (photosensitive member), is rotatably supported in the direction of an arrow. Around the photosensitive drum 1, a pre-exposure lamp 11, a corona charger 2, a laser exposure optical system. System (exposure means) 3, potential sensor 12, four developing units (developing means) 4y of different colors,
4c, 4m, 4bk, a light amount detecting means 13, a transfer device (transfer means) 5, and a cleaning device 6 are arranged.

In the laser exposure optical system 3, an image signal from the reader unit is converted into an optical signal by a laser output unit (not shown), and the converted laser light is reflected by the polygon mirror 3a, and is converted into a lens signal. The light is projected on the surface of the photosensitive drum 1 through the mirror 3b and the mirror 3c.

At the time of image formation in the printer section, the photosensitive drum 1 is rotated in the direction of the arrow in the figure, and the photosensitive drum 1 after having been neutralized by the pre-exposure lamp 11 is uniformly charged by the corona charger 2 so that each of the separated colors is separated. Each time, a light image E is irradiated to form a latent image.

Next, a predetermined developing device is operated to develop the latent image on the photosensitive drum 1 to form a toner image on the photosensitive drum 1 using a resin as a base. Each developing unit 4y, 4c, 4
m and 4bk are eccentric cams 24y, 24c and 24, respectively.
By the operations of m and 24bk, the photosensitive drum 1 is selectively approached in accordance with each separation color.

Further, the toner image on the photosensitive drum 1 is
A paper feed motor (feeding means) 2 from a recording material cassette (storage unit) 7a or 7b or a manual tray (paper feed unit) 7d
By driving 3a or 23b, the paper feed vertical path (conveyance unit)
26, the sheet is guided to a paper feed horizontal path (transport section) 27, and is transferred to a recording material supplied to a position facing the photosensitive drum 1 via feeding means such as horizontal path motors 23d and 23e and the transfer device 5. Is done.

In the present embodiment, the transfer device 5 includes a transfer drum 5a,
A transfer brush 5b, a suction roller 5g opposed to a suction brush 5c for electrostatically sucking the recording material, an inner charger 5d,
A transfer sheet 5f made of a dielectric material and carrying a recording material is laminated on a connecting plate 5i in the peripheral opening area of the transfer drum 5a having an outer charger 5e and rotatably supported. It is stretched integrally in a cylindrical shape. As the transfer sheet 5f, a dielectric sheet such as a polycarbonate film is used.

Then, as the drum-shaped transfer device 5, ie, the transfer drum 5a is rotated, the toner image on the photosensitive drum is transferred onto the recording material carried on the transfer sheet 5f by the transfer brush 5b.

As described above, a desired number of color images are transferred to the recording material sucked and conveyed to the transfer sheet 5f, and a full-color image is formed.

In the case of forming a full-color image, when the transfer of the toner images of four colors is completed as described above, the recording material is separated from the transfer drum 5a by a separating claw (separating means) 8a, a roller 8b for separating and pushing up, and a separating charger 5h. Separated by the action of
The sheet is discharged to a tray 10 via a fixing device 9 using a heat roller.

On the other hand, the post-transfer photosensitive drum 1 is subjected to the image forming process again after the residual toner on the surface is cleaned by the cleaning device 6. The transfer drum 5a is also cleaned by the cleaning device 18.

Next, when images are formed on both sides of the recording material, the conveyance path switching guide 19 is driven immediately after the recording material is discharged from the fixing device 9, and the recording material is passed through a paper discharge vertical path 20 and a double-sided path 21 a. And stored in the double-sided deck 22 by the U-turn roller 21b. Thereafter, the recording material is fed by the paper feed motor 23c and an image is formed on the other surface of the recording material again by the above-described image forming process.

Further, in order to prevent scattering of powder on the transfer sheet 5f of the transfer device 5 and adhesion of oil to the recording material, the brush 14 is opposed to the fur brush 14 via the transfer sheet 5f. The backup brush 15, the oil removing roller 16, and the transfer sheet 5f
The cleaning is performed by the action of the backup brush 17 opposed to. Such cleaning is performed before or after image formation,
In addition, it is performed as needed when a jam (paper jam) occurs.

The gap between the transfer sheet 5a and the photosensitive drum 1 can be arbitrarily set by operating the eccentric cam 25 at a desired timing and operating the cam follower 5j integrated with the transfer drum 5f. And For example, during standby or when the power is off, the interval between the transfer drum 5a and the photosensitive drum 1 is increased.

[Sheet Feeding Control] In order to continuously and stably convey the recording material to a predetermined position on the transfer drum rotating at the image forming speed, the recording material cassette 7 is used.
From the positions a and 7b to the registration roller in front of the transfer drum 5a, the sheet must be conveyed at a speed higher than the speed at which it is sent to the transfer drum 5a, that is, the image forming speed.

In this embodiment, a stepping motor is used for each of the paper feeding motors of the feeding means in order to realize such a variable speed paper feeding control. By using this stepping motor, the configuration of the drive system for shifting can be simplified,
It is possible to stably produce the accuracy of the position or time of the sheet feeding.

[Material Process Control] In an electrophotographic image forming apparatus, thick paper such as postcards and OHP sheets can be printed on materials other than plain paper, but process control different from plain paper is possible. May be required.

For example, when printing on thick paper of 150 g / m ² or more, since thick paper has a so-called stiffness of paper, a stronger suction force to the transfer drum 5 a is required. Therefore, the charge on the transfer sheet 5f by the inner charger 5d and the outer charger 5e is increased by one rotation of the transfer drum to increase the charge amount (this is referred to as suction rotation).

In the case of an OHP sheet, the process from adsorption to transfer is the same as that of plain paper, but the fixing speed is reduced to improve the fixing property. Then, in order to take the deceleration time of the transfer drum 5a in accordance with the fixing speed, the transfer drum 5a is rotated by one rotation more than usual (this is called resume rotation).

In the case of a postcard, since the postcard itself is a thick paper, suction rotation is necessary as in the case of the above-mentioned thick paper. In addition, resuming rotation is required to improve the fixing property.

[Conveyance Speed for Each Material] In addition to the above-described process control for each material, the conveyance speed is switched for each material in terms of the transportability of the recording material.

In the case of plain paper, as described above, the paper is conveyed from the recording material cassettes 7a and 7b to the registration rollers in front of the transfer drum 5a at an increased speed. However, in the case of an OHP sheet, the transportability is inferior to that of plain paper. Therefore, the sheet cannot be transported at an increased speed. For this reason, the transport speed is the same as the image forming speed.

In the case of postcards and thick paper, the paper cannot be conveyed from the recording material cassettes 7a and 7b.
The paper is conveyed only from d. The transport speed is the same as the image forming speed, similar to the OHP.

FIG. 2 is a block diagram showing details of an embodiment of the present invention based on the above configuration.

In FIG. 2, M1 is a stepping motor (1) used for the horizontal path motor 23d located on the upstream side in the conveying direction of the recording material. The stepping motor (1) conveys the recording material by a roller driven by the motor M1. The recording material is curled to enhance the adsorbability of 5a. M2 is a stepping motor (2) used for a horizontal path motor 23e located downstream of the horizontal path motor 23d, and drives a registration roller on the downstream side and a roller for conveying a recording material to the transfer drum 5a. The load torque of the motor M1 is larger than that of the motor M2 by curling the recording material, and the difference between the two load torques is more remarkable as the recording material becomes thicker and harder.

IC1 and IC2 are motors M1 and M1, respectively.
In the drive circuit of M2, according to the reference level input as the Ref1, Ref2 signal, the motor M1,
The driving current of M2 is controlled with a constant current. R8, R9 and R1
0 and R11 are detection resistors for detecting currents flowing through the motors M1 and M2, and IC3 and IC4 are motor clocks (Mcl) from a sequence control unit (not shown).
ock1 and Mclock2), each motor M
A phase signal generating circuit for generating and outputting an excitation phase signal to the drive circuits IC1 and IC2 of the M1 and M2, and serves as an exciting current switching means. R1, R2, R3, R4, R5, R
6, R7, Q1, Q2, Q3 and D1 are current switching bit signals (CU) from a sequence control unit (not shown).
1, CU2), a resistor, a transistor, and a diode that serve as a reference signal generator.

Table 1 shows the current switching bit signal (CU
1, CU2). H / L of CU1 and CU2
(High level / Low level) as shown in Table 1,
The combination of the current settings of the motors M1 and M2 is Mode0, M
mode1 and Mode2.

[0043]

[Table 1]

The modes switched as shown in Table 1 above are:
The mode is switched and used for each mode shown in Tables 2, 3, and 4.

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

In this embodiment, there are a single color mode (Table 2) using only one of the four colors of toner and a full color mode (Table 3) using four colors of toner. In addition, a recovery operation mode (Table 4) is provided in which a recording material staying on the recording material transport path is evacuated to a safe place when a jam or some error occurs.

In the full-color mode, when one or two sheets of recording material are conveyed to be attracted onto a transfer sheet, the transfer drum 5a rotates four times to sequentially transfer toner of four colors. The horizontal path motors of the motors M1 and M2 are excited for approximately one rotation of the transfer drum during the sheet feeding operation,
It is not excited during three rotations until the next recording material is conveyed.

On the other hand, in the single-color mode, only one color needs to be transferred, so that one or two sheets of recording material are completely transferred for one rotation of the transfer drum to be attracted onto the transfer sheet, and the horizontal path motor is constantly driven. The recording material must be conveyed, and the excitation of the motor is not cut off.

The suction rotation and the resuming rotation described above are applied to the single-color and full-color, as needed, depending on the recording material feeding stage and the material of the recording material, but the motor is not excited during this period.

The duty ratio shown in the table represents the ratio of the excitation time.

The transfer speed in the table indicates the transfer speed for transferring to the registration roller in front of the transfer drum and the transfer speed for the transfer drum 5.
The transfer speed at the time of transfer to “a” is shown. Although the stepping motor is driven by a constant current chopper method, the effective current is stopped for the longest time and decreases as the driving speed increases. In other words, when the sheet is conveyed at a low speed, the driving torque can be increased, but the self-temperature rise increases.

Normally, in the full-color mode, since the duty used by the motor is low, even if a large amount of current is applied to increase the driving torque, the self-heating does not pose a problem. Similarly, even in the single color mode, the use duty of the cardboard, the postcard, and the like is low due to the suction rotation and the resumption rotation.

On the other hand, when the plain paper is conveyed in the monochromatic mode, there is no time when the motor is not excited, the duty used becomes 100%, and the self-heating becomes a problem. Is not large, so that the exciting current can be set small accordingly.

Further, in the recovery operation mode in which the recording material staying on the recording material transport path is evacuated to a safe place when a jam or some error occurs, it is necessary to generate the maximum drive torque. Since it is a regular case only, the usage time is extremely short, and self-heating does not matter.

An appropriate mode is selected in consideration of the use duty and the load torque required for each of these modes, so that the recording material is stably conveyed. By using this method, it is not necessary to use an unnecessarily large and expensive motor to satisfy both the driving torque and the self-heating, and it is effective in terms of cost and space.

FIG. 3 is a schematic flowchart showing the processing operation of the above-described embodiment. The control processing shown here is executed according to a program stored in advance by the above-mentioned sequence control unit (not shown).

When the copy switch of the copying machine is depressed and turned on (S1), the sequence control unit selects an image process according to the type of the recording material, and drives the stepping motor for feeding the recording material according to the image process. The mode is determined (S2). Then, the exciting current of the stepping motor is set and switched for each mode (S3), and the stepping motor is driven by the exciting current (S4).

[0060]

As described above, according to the present invention,
By transporting the recording material by selecting an appropriate mode based on the balance between the use duty and load torque required in each paper feed transport mode, it is unnecessary and expensive to satisfy both drive torque and self-heating. This eliminates the need for a motor, and is cost and space efficient.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of an image recording apparatus according to the present invention.

FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 3 is a flowchart illustrating a processing operation according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive drum 3 Laser exposure optical system (exposure means) 4y Developing device (developing device) 4c Developing device (developing device) 4m Developing device (developing device) 4bk Developing device (developing device) 5 Transfer device (transfer device) 7a Recording material Cassette (storage unit) 7b Recording material cassette (storage unit) 7d Manual feed tray (paper feed unit) 8 Separation claw (separation unit) 9 Fixing unit (fixing unit) 23a Feed motor (feed unit) 23b Feed motor (feed) 23c Paper feeding motor (feeding means) 23d Horizontal path motor (feeding means) 23e Horizontal path motor (feeding means) 26 Paper feeding vertical path (conveying section) 27 Paper feeding horizontal path (conveying section) M1 Stepping motor M2 Stepping motor IC1 Drive circuit IC2 Drive circuit IC3 Phase signal generation circuit (switching means) IC4 Phase signal generation circuit (switching means)

Claims (7)

[Claims] 1. A stepping motor control device for controlling the driving of a stepping motor, wherein a switching means for switching an exciting current of the stepping motor is provided, and the exciting current is switched according to a driving mode of the stepping motor. 2. An electrophotographic image recording apparatus, comprising:
A feeding unit that feeds a recording material using a stepping motor; and a switching unit that switches an exciting current of the stepping motor. The exciting current of the stepping motor is switched by an image forming process according to the type of the recording material. An image recording apparatus for feeding a recording material. 3. The image recording apparatus according to claim 2, wherein a plurality of stepping motors of the feeding means are provided, and respective exciting currents of the stepping motors are switched. 4. The stepping motor is not excited when the recording material is not fed.
The image recording apparatus as described in the above. 5. A feeding device for feeding a recording material from a storage portion for the recording material, a feeding device for feeding an arbitrary recording material from a manual paper feeding portion, and a transport portion for passing the recording material. The image recording apparatus according to any one of claims 2 to 4, further comprising a feeding unit configured to feed the recording material. 6. A method for controlling an electrophotographic image recording apparatus, wherein a recording material is fed using a stepping motor, and an exciting current of the stepping motor is controlled by an image forming process according to the type of the recording material. A recording material is fed by switching the image recording apparatus. 7. A method according to claim 6, wherein the stepping motor is not excited when the recording material is not fed.