JPH1198895A - Step out detecting device for stepping motor and image forming device using stepping motor provided with step out detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an step out detecting device which can immediately detect the step out of a stepping motor, when the motor steps out and an image forming device using a stepping motor provided with this step out detecting device. SOLUTION: When a stepping motor 401 is controlled to a constant-current state by means of a constant-current driver 400, an step out detecting device converts the current flowing to the motor 401 into a voltage by means of a current detecting resistor 402, detects the frequency component of the current by means of an F/V converter 403, ORs the frequency components of the current when the motor 401 is normally operated, and when the motor 401 steps out by means of an OR circuit 406 by comparing the frequency components with each other by means of comparators 404 and 405, and discriminates whether or not the motor 401 is out of step from the output value of the OR circuit 406 by means of a CPU 407. An image forming device uses the stepping motor 401 provided with the step out detecting device for a paper feeding roller which feeds recording paper to an image forming section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor out-of-step detecting device and an image forming apparatus using the stepping motor having the out-of-step detecting device.

[0002]

2. Description of the Related Art Conventionally, step-out of a stepping motor is detected by detecting an object moved by the stepping motor with an optical sensor or the like, and stepping out when the object does not move despite driving the motor. Was determined.

[0003]

However, in the above-mentioned prior art, since step-out of the stepping motor is inferred from secondary factors, it takes time to determine that step-out has occurred. May cause damage to the device body in which the is incorporated.

SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide a method for detecting a step-out of a stepping motor by monitoring a current flowing through the stepping motor itself and reading a frequency component to immediately recognize that the stepping-out has occurred. It is to provide a device.

A second object of the present invention is to provide an image forming apparatus using a stepping motor provided with a step-out detecting device of the type described above.

[0006]

In order to achieve the first object, the present invention provides a current detecting means for detecting a current flowing through a stepping motor and a frequency component of the current detected by the current detecting means. Using a stepping motor out-of-step detecting device, comprising: a frequency component detecting unit that performs stepping motor; and a determining unit that determines whether the stepping motor has stepped out based on the frequency component detected by the frequency component detecting unit. It is.

More specifically, in the stepping motor step-out detecting device according to the present invention, the current detecting means comprises a current detecting resistor for detecting a current flowing through the stepping motor and converting the current into a voltage. The component detecting means comprises an F / V converter which adds each frequency component of the voltage detected and converted by the current detecting resistor and integrates for a predetermined time, and the determining means outputs the output of the F / V converter. 2 for comparing with two predetermined reference voltages
It comprises a comparator, an OR circuit for performing an OR operation on the outputs of the two comparators, and a CPU for determining whether or not step-out has occurred based on the output value of the OR circuit.

In order to achieve the second object, the present invention relates to an image forming apparatus using a stepping motor provided with a step-out detecting device, wherein a paper feed roller for feeding recording paper to an image forming section is provided. In an image forming apparatus using a stepping motor, drive instructing means for instructing driving of the stepping motor, step-out determining means for determining step-out of the stepping motor during driving of the stepping motor by the drive instruction means, and step-out determining means When it is judged that it is not out of step by means,
An image forming means for forming an image after the trailing edge of the recording paper has passed through the paper feed roller, and when the step-out determining means determines step-out, the stepping motor is started slowly at a slower steady speed than usual. An image forming apparatus is provided which has a discharge unit that discharges the recording paper whose conveyance has stopped due to step-out by driving.

In the image forming apparatus of the type described above, when the step-out determining means determines that the step-out has occurred, the step-out determining means for determining whether the step-out has occurred continuously for a predetermined number of times or more is provided. When it is determined that the step-out has occurred continuously for a predetermined number of times or more by the continuous step-out determining means, an error is displayed and the step-out determining means continuously performs the step-out for a predetermined number of times. When it is determined that the above has not occurred,
By driving the stepping motor at a slower steady speed with a slower startup than usual, the recording paper whose conveyance has stopped due to step-out is discharged.

In the image forming apparatus of the above-mentioned type, there is further provided a second step-out determining means for determining whether or not step-out has occurred when the stepping motor is driven at a slow steady-state speed with a slower startup than usual. Preferably, the second
When the step-out determining means determines that step-out has occurred, an error is displayed. When the step-out determining means determines that step-out has not occurred, the step-out determining means waits for the discharge of the recording paper by the discharging means. Activate the drive instruction means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described by taking a stepping motor used in a digital color copying machine as an example. As a premise, the configuration of the entire digital color copying machine will be described first. FIG. 3 is a schematic cross-sectional view of the digital color copying machine. The digital color copying machine shown in FIG. 3 has a reader unit at the upper part and a printer unit at the lower part. Hereinafter, the reader unit and the printer unit will be described separately.

Structure of the reader unit: In FIG. 3, 101 is a CCD, 311 is a substrate on which the CCD 101 is mounted, 31
2 is a digital image processing unit (this image processing unit is a CCD 10
1 and the binary conversion unit 201 and the delay unit 20 shown in FIG.
2 to 205), 301 is a platen glass, 302 is a document feeder (DF) (this document feeder 302
Instead of a mirror pressure plate (not shown)),
Reference numerals 303 and 304 denote light sources (halogen lamps or fluorescent lamps) for illuminating the original, and reference numerals 305 and 306 denote light sources 303 and 30.
4, a reflector for condensing the light 4 on the original, 307 to 309 mirrors, 310 a reflected light or a projected light from the original
The lens 314 condenses light on the halogen lamp 30.
Reference numerals 315 and 313 denote a carriage that houses the mirrors 308 and 309, and 313 denotes an interface (I / F) unit with another CPU or the like.

The entire surface of the document is scanned by mechanically moving the carriage 314 at a speed V and the carriage 315 at a speed V / 2 in a direction perpendicular to the electrical scanning (main scanning) direction of the CCD 101. (Sub scanning).

FIG. 4 is a block diagram showing a detailed configuration of the digital image processing unit 312. The original on the platen glass reflects light from the light sources 303 and 304 (FIG. 3), and the reflected light is guided to the CCD 101 and converted into an electric signal. In the case where the CCD 101 is a color sensor, RGB 101
Even if the color filters of R, G and B filters are mounted in-line on a one-line CCD in the order of RBG, the R filter, G filter and B filter
The filters may be arranged for each D, the filters may be on-chip, or the filters may be configured differently from the CCD. Then, the electric signal (analog image signal) is input to the image processing unit 312, and the clamp & Am
p. & S / H & A / D unit 102 sample and hold (S
/ H), the dark level of the analog image signal is clamped to the reference potential, amplified to a predetermined amount (the processing order is not limited to the notation order), A / D converted, and, for example, RGB.
Each bit is converted to a digital signal.

After the shading section 103 performs shading correction and black correction on the RGB signals, the splicing processing, MTF correction, and original detection are performed by a splicing & MTF correction & original detecting section 104. That is, in the splicing process, when the CCD 101 is a three-line CCD, the reading positions between the lines are different. Therefore, the delay amount for each line is adjusted according to the reading speed, and the signal timing is adjusted so that the reading positions of the three lines become the same. In the MTF correction, since the reading MTF changes depending on the reading speed and the magnification, the change is corrected, and in the document detection, the document size is recognized by scanning the document on the platen glass.

The digital signal whose read position timing has been corrected is input to the CCD 101 by the input masking unit 105.
Spectral characteristics and light sources 303, 304 and reflector 305,
The spectral characteristic of 306 is corrected. Input masking unit 105
Is a selector 1 that can be switched with an external I / F signal.
06. The signal output from the selector 106 is input to the color space compression & background removal & LOG conversion unit 107 and background removal unit 115. After the signal input to the background removal unit 115 is removed from the background, the signal is input to a black character determination unit 116 that determines whether or not the document is a black character in the document, and a black character signal is generated from the document.

The color space compression / background removal / LOG conversion unit 107 to which the output of another selector 106 is input.
Then, color space compression determines whether the read image signal is within the range that can be reproduced by the printer, and if so, corrects it so that the image signal falls within the range that can be reproduced by the printer. . Then, a background removal process is performed, and the CMY signals are converted from the RGB signals by LOG conversion.
Convert to a signal. Then, the timing of the output signal of the color space compression & background removal & LOG conversion unit 107 is adjusted by the delay 108 in order to correct the signal generated by the black character determination unit 116 and the timing. The two types of signals are subjected to moiré removal by the moiré removal unit 109 and subjected to scaling processing in the main scanning direction by the scaling unit 110.

Reference numeral 111 denotes a UCR & masking & black character reflecting unit. The CMY signal processed by the scaling unit 110 is generated by the UCR process to generate a CMYK signal, which is corrected by the masking processing unit into a signal corresponding to the output of the printer. Along with
The determination signal generated by the black character determination unit 116 is fed back to the CMYK signal. The signal processed by the UCR & masking & black character reflection unit 111 is subjected to density adjustment by the γ correction unit 112 and then subjected to smoothing or edge processing by the filter unit 113.

The signal which has been smoothed or edge-processed by the filter unit 113 is subjected to L-shading by the head shading unit 117.
Head shading correction for correcting unevenness in the main scanning direction of the ED head is performed. The data used for this head shading is obtained by printing a predetermined image
D101, read by Clamp & Amp. & S /
The data performed up to A / D conversion of the H & A / D unit 102 is
After processing such as thinning and averaging is performed by the head shading sampling unit 118, the stored data is used.
The signal processed as described above is converted by the binary conversion unit 201 shown in FIG.
The bit multi-level signal is converted to a binary signal. (The conversion method may be any of the dither method, the error diffusion method, or an improved version of the error diffusion method.)

Configuration of the printer unit: In FIG.
Is a Y image forming section, 318 is an M image forming section, 319 is a C image forming section, and 320 is a K image forming section. Since the respective structures are the same, the Y image forming section 317 will be described in detail, and other image forming sections will be described. Description of the unit is omitted.

In the Y image forming section 317, reference numeral 342 denotes a photosensitive drum, on which a latent image is formed by light from the LED array 210 driven by an ultrasonic motor (not shown). A primary charger 321 charges the surface of the photosensitive drum 342 to a predetermined potential to prepare for forming a latent image. A developing device 322 develops the latent image on the photosensitive drum 342 to form a toner image. Note that the developing device 322 includes a sleeve 345 for applying a developing bias to perform development.

Reference numeral 323 denotes a transfer charger, which is a transfer belt 3
Discharge is performed from the back surface of the transfer belt 33, and the toner image on the photosensitive drum 342 is transferred to a recording paper or the like on the transfer belt 333. In this embodiment, since the transfer efficiency is good, no cleaner portion is provided. (It goes without saying that there is no problem even if the cleaner is installed.)

Next, a procedure for forming an image on a recording paper or the like will be described. The recording paper and the like stored in the cassettes 340 and 341 are fed one by one by pickup rollers 339 and 338, and are supplied onto the transfer belt 333 by paper feed rollers 336 and 337. The paper feed roller 336 is driven by the stepping motor 401. The stepping motor 401 is connected to a step-out detecting device described later.

Next, the fed recording paper is applied to the attraction charger 3
Charged at 46. Reference numeral 348 denotes a transfer belt roller that drives the transfer belt 333 and
6, the recording paper or the like is charged, and the transfer belt 333 is charged.
To adsorb recording paper. A paper edge sensor 347 detects the edge of a recording sheet or the like on the transfer belt 333.
The detection signal of the paper leading edge sensor 347 is sent from the printer unit to the color reader unit, and is used as a sub-scanning synchronization signal when a video signal is sent from the color reader unit to the printer unit.

Thereafter, the recording paper or the like is conveyed by the transfer belt 333, and is transferred to the image forming units 317 to 320 in the Y direction.
A toner image is formed on the surface in the order of MCK. The recording paper or the like that has passed through the K image forming unit 320 is transferred to the transfer belt 33.
In order to facilitate the separation from the transfer belt 333, the toner is removed from the transfer belt 333 after the charge is removed by the charge removing charger 349. 350
Reference numeral denotes a peeling charger, which prevents image disturbance due to peeling discharge when recording paper or the like is separated from the transfer belt 333. The separated recording papers and the like are used to charge the pre-fixing chargers 351 and 352 in order to compensate for the toner adsorption force and prevent image disturbance.
After the toner image is thermally fixed by the fixing unit 334, the toner image is discharged to the paper discharge tray 335.

Next, LED image recording will be described.
Binary YMCK generated by the image processing unit of FIGS. 4 and 5
Are adjusted to the predetermined positions of the four colors by adjusting the difference in the distance between the paper edge sensor and each image forming unit by the delay units 202 to 205 based on the paper edge signal from the paper edge sensor 347. It becomes possible to print. LED drives 206 to 209 are LEDs 210 to 213
To generate a signal for driving.

Next, a stepping motor out-of-step detecting device of the present invention used for the stepping motor 401 for driving the paper feed roller 336 will be described. At first,
A case where the stepping motor is rotating normally will be described. When the motor is rotating normally, the chopping frequency of the current for the constant current control has a substantially constant value even when the rotation speed and the motor temperature change as shown in FIG. 2A-1.
Therefore, the frequency component has a higher specific frequency as shown in FIG. 2A-2.

Next, when the stepping motor loses synchronism, in this case, the limit current value (I _OH ) is the same value as in the normal state, but the chopping frequency is disturbed as shown in FIG. , Frequency components are high over a wide band as shown in FIG. 2b-2.

Therefore, in the present invention, step-out detection is performed by detecting a difference in the frequency component of the current flowing through the stepping motor between normal rotation and step-out. FIG. 1 is a schematic diagram of an apparatus for detecting this frequency component and detecting step-out of the stepping motor. In FIG. 1, reference numeral 400 denotes a constant current driver for controlling the motor with a constant current;
Is a stepping motor; 402 is a current detection resistor for converting the current flowing through the stepping motor into a voltage;
3 is an F / V (frequency / voltage) converter, 404, 40
5 is a comparator, and 406 is an OR circuit.

The current flowing through the stepping motor 401 is converted into a voltage Vs by the current detecting resistor 402.
The voltage Vs is fed back to the constant current driver 400, and is compared with a reference voltage Vref by a comparator inside the constant current driver 400. As a result of the comparison, when the voltage becomes higher than the voltage Vref, the FET (or transistor) in the constant current driver 400 is turned off, and the current supply to the stepping motor 401 is stopped. Also, inside the constant current driver 400, there is a time constant circuit composed of a capacitor and a resistor.
When the charge in the capacitor decreases below a certain value, the FET is turned on again, and a current flows through the stepping motor 401. By repeating this operation, the stepping motor 401 is driven at a constant current.

The voltage Vs obtained by converting the current flowing through the stepping motor 401 is fed back to the constant current driver 400 and is also input to the F / V converter 403. The F / V converter 403 integrates a value obtained by adding all the magnitudes of the respective frequency components of the detection signal for a predetermined time and outputs the result as a voltage Vfv. F / V converter 403
2a-3 shows the output during normal rotation, and FIG. 2b-3 shows the output during step-out.

At the time of normal rotation, the value of Vfv shows a substantially constant value, and falls within a range between predetermined reference voltages Vref1 and Vref2. It may fall outside the range between Vref2. Therefore, as shown in FIG.
4 is configured such that Vref1 is input to the negative input terminal, Vfv is input to the positive input terminal, Vref is input to the positive input terminal of the comparator 405, and Vfv is input to the negative input terminal.

Vfv is the reference voltage Vref1, Vref2
When the values are within the range, the two comparators output “L”, the output of the OR circuit 406 also becomes “L”, and the CPU 407 determines that the rotation is normal. When Vfv is higher than the reference voltage Vref1 (the range of Mh in FIG. 2B-3), the output of the comparator 404 becomes “H”, and when Vfv is lower than the reference voltage Vref2 (FIG. 2B).
(Ml range of -3) when the output of the comparator 405 is'
H ′, and the output of the OR circuit 406 becomes'
H '. At this time, the CPU 407 determines that the stepping motor 401 has stepped out. At that time, CPU4
07 performs optimal control on the load (motor, clutch, solenoid, etc.) of the copying machine body.

The control flow will be described with reference to FIG. At step S1, the control starts. In step S2, the stepping motor 401 is turned on. In step S3, it is determined whether or not the stepping motor 401 has stepped out. At this time, the above-mentioned step-out detection signal is “L”.
If it is normal, it is out of step if it is 'H'. If it is determined in step S3 that there is no step-out, step S11 is performed.
Then, it is determined whether or not the trailing edge of the paper has passed through the paper feed roller 336. This determination is made by a post-registration sensor (not shown) provided near the paper feed roller in FIG. Step S1
In step 1, the detection of the step-out is repeated until it is determined that the sheet is to be removed from the sheet feeding roller. If it is determined that the paper feed roller has been removed, image formation is performed in step S12, and the process ends in step S13.

In step S3, the stepping motor 40
If it is determined that step-out 1 has stepped out, the number of step-outs is determined in step S4. If step-out has occurred continuously n times or more, an error is displayed on the display unit in step S9. In S10, the process ends.

If it is determined in step S4 that the number of steps out is less than n, in step S5, the phase signal of the stepping motor is stopped and the excitation of the motor is stopped. At this time, since the paper remains on the paper feed roller, step S6
Thus, a phase signal is output such that the motor rotates at a slower startup curve and a lower rotation speed than usual. By doing so, the motor can rotate with a larger torque than during normal rotation. However, if the step-out still occurs (judgment in step S14), it is impossible to return by turning the motor, so the flow jumps to step S9, displays an error, and ends. If it is determined in step S14 that there is no step-out, the process proceeds to step S7, and it is determined whether or not the paper stopped at the sheet feed roller due to the step-out of the motor is discharged. This determination is made by a sensor installed in the vicinity of the paper discharge port not shown in FIG. Steps S6 and S14 are repeated until it is determined in step S7 that the paper has been discharged. If it is determined that the paper has been ejected, in step S8, the copy is not performed due to the step-out of the motor.
Resume copying. Then, the process returns to step S2.

[0037]

As described above, according to the present invention,
Detects stepping motor out-of-step in real time, prevents image formation at that time, reduces damage to the main unit, and if the user processes it as jam at the time of out-of-step, as long as the motor rotates If this is the case, automatic restoration can be performed, and the user's labor can be saved.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a step-out detecting device for a stepping motor according to an embodiment of the present invention.

FIG. 2 is a graph for explaining a distribution of frequency components for detecting step-out of a stepping motor and a criterion using a voltage converted from the frequency components.

FIG. 3 is a schematic cross-sectional view showing a configuration of a digital color copying machine as an example using a stepping motor.

FIG. 4 is a block diagram illustrating an image processing process of the digital color copying machine.

FIG. 5 is a block diagram illustrating a developing process for each color after the image processing process.

FIG. 6 is a flowchart of control of an image forming operation of the digital color copying machine including a step-out detection step.

[Explanation of symbols]

 101 CCD 312 Image processing unit 317-320 Image forming unit 333 Transfer belt 400 Constant current driver 401 Motor 402 Current detection resistor 403 F / V converter 404, 405 Comparator 406 OR circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuro Fukusaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Michio Kawase 3- 30-2 Shimomaruko, Ota-ku, Tokyo Within Non Corporation (72) Inventor Toshihiko Otsubo 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Corporation

Claims (5)

[Claims] A current detecting means for detecting a current flowing through the stepping motor; a frequency component detecting means for detecting a frequency component of the current detected by the current detecting means; and a frequency component detecting means for detecting the frequency component detected by the frequency component detecting means. Determining means for determining whether or not the stepping motor has stepped out based on the stepping motor. 2. The stepping motor out-of-step detecting device according to claim 1, wherein said current detecting means comprises a current detecting resistor for detecting a current flowing through the stepping motor and converting the current into a voltage, and said frequency component detecting means. Is composed of an F / V converter that integrates a predetermined time after adding each frequency component of the voltage detected and converted by the current detection resistor, and the determination unit determines the output of the F / V converter in advance. It comprises two comparators for comparing with two reference voltages, an OR circuit for performing an OR operation on the outputs of the two comparators, and a CPU for determining whether or not a step-out has occurred based on an output value of the OR circuit. A step-out detection device for stepping motors. 3. An image forming apparatus using a stepping motor provided with a step-out detecting device, wherein the stepping motor is used as a feed roller for feeding recording paper to an image forming section. A step-out determining means for determining step-out of the stepping motor while the stepping motor is being driven by the drive instruction means; and An image forming means for forming an image after the trailing end of the paper feed roller has been pulled out, and when the step-out determining means determines step-out, the stepping motor is driven at a slower steady speed with a slower startup than usual. An ejection unit for ejecting the recording paper whose conveyance has stopped due to step-out of the image forming apparatus. 4. The image forming apparatus according to claim 3, wherein
When the step-out determining means determines that the step-out occurs, the step-out determining means further includes a continuous step-out determining means for determining whether or not the step-out has occurred continuously a predetermined number of times or more. When it is determined that the stepping motor has occurred continuously for a predetermined number of times or more, an error display is performed. An image forming apparatus characterized in that the recording paper whose conveyance has stopped due to step-out is discharged by driving at a low steady speed when raised. 5. The image forming apparatus according to claim 3, wherein
The stepping motor further includes a second step-out determining means for determining whether or not step-out has occurred when the stepping motor is driven at a slower steady speed with a slower startup than normal, and step-out occurs in the second step-out determining means. When it is determined that there is no step-out, when the second step-out determining means determines that no step-out has occurred, the drive instructing means is operated after waiting for the discharge of the recording paper by the discharging means. Image forming apparatus.