JP2001346397A - Apparatus and method for forming image, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage medium, an image forming apparatus and an image forming method which enable sufficient torque outputting of a motor, along with suppressing its noise and vibration, by performing necessary minimum control of the time constant of a filter for removing noise. SOLUTION: In the image forming apparatus having a constant-current chopping control circuit, the constant-current chopping control circuit has a means for setting a predetermined current value, a means which detects the voltage value of a current detecting resistor for detecting current flowing in the motor, a means for comparing the output value of the voltage detecting means with a reference voltage through the use of a comparator, a noise removing means which is inserted between the spots of the reference value and the detected voltage value to be applied to the input portions of this comparator, and changes-over/selects a plurality of time constants, and a means which on/off- controls the current flowing in the motor, on the basis of the comparison result. The time constants for noise removal are changed and controlled depending on the magnitude of a load to be driven by the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus having a motor driving device for supplying a current to a motor, such as a stepping motor, which sequentially rotates an excitation phase and rotates by a constant current chopping control method.

[0002]

2. Description of the Related Art A constant current circuit for controlling a motor driving current in a motor driving device to a constant value includes a reference voltage set by a reference voltage dividing resistor, a voltage value of a current detecting resistor for detecting a current flowing through the motor, and Are compared by a comparator, and ON / OFF control (chopping control) of the current flowing into the motor is performed based on the comparison result. However, during the actual chopping operation, the MOS
Under the influence of an SW element such as an FET, ringing noise is superimposed on the current detection signal, which causes erroneous detection of the comparator. Generally, as shown in FIG. 1, a filter is connected between the current detection resistor and the comparator to prevent this malfunction. When the excitation pulse is input to the motor, as shown in FIG. 3B, the constant of the filter is set so that the current flows into the reference current value determined by r1 and r2 immediately after the input of the phase switching signal. Set. Thus, the motor can output a specified torque.

[0003]

However, when a stepping motor is used for driving the paper transport of the image forming apparatus, the transport roller to be driven is accelerated from a stopped state with a thick paper or the like sandwiched between the transport rollers, or in a high-speed rotation region. High torque may be required, for example, when paper enters the rollers, while torque, such as when accelerating from a state where paper does not exist on the rollers, is extremely small compared to the former. is there. In particular, when the mechanical configuration driven by the motor is low in both inertia and static torque, the difference is large. In this case, during acceleration control, strong earthquake step-out due to excessive torque or unpleasant vibration noise may occur. As a solution to the above problem, there is a method of interposing a rubber damper between a motor and a motor mounting device to absorb vibrations caused by the motor. However, this method has problems that the damper is expensive and that a space for mounting the damper is required between the motor and the mounting device.

The present invention has been made in view of the above circumstances, and when starting a motor under a light load condition, a pseudo soft start control is performed by increasing the time constant of a filter to generate a smooth torque. In addition, while suppressing noise and vibration, at the time of startup when it is determined that a load greater than a predetermined load is applied to the motor, and when the motor is in a steady rotation state, the time constant of the filter for noise removal is reduced. It is an object of the present invention to provide an image forming apparatus, an image forming method, and a storage medium in which the motor is controlled to be reduced to a necessary and sufficient value so that the torque output of the motor can be sufficiently exhibited.

[0005]

The present invention can solve the above-mentioned problems by providing the following constitution.

(1) In an image forming apparatus having a control system with a constant current chopping control circuit for controlling a motor such as a stepping motor which rotates by sequentially switching excitation phases so as to keep a drive current constant, The control circuit includes a reference voltage setting means for setting a predetermined current value, a voltage detection means for detecting a voltage value of a current detection resistor for detecting a current flowing through the motor, and the reference voltage setting means. Comparing means such as a comparator for comparing the output values of the comparator and the voltage detecting means, and at least two or more time constants can be switched and selected between a reference voltage value applied to an input portion of the comparator and a detected voltage value. A control system for controlling ON / OFF (chopping control) of a current flowing through a motor based on a comparison result of a simple noise removing unit and the comparing unit. And means, an image forming apparatus and controls the switching of the time constant of the noise is removed by the magnitude of load said motor is driven.

(2) When the load driven by the motor is larger than a predetermined value, a sufficient time constant is selected because noise removal is required. On the other hand, when the load is smaller than the predetermined value and the motor is started. In the case of time, a time constant greater than the time constant is selected.

(3) The image forming apparatus as described in (2) above, wherein when the motor is started, the speed is accelerated.

(4) The image forming apparatus according to the above (1), wherein the noise removing means is a noise filter constituted by a resistor R and a capacitor C.

(5) The time constant switching selection function is as follows:
The image forming apparatus according to (1), wherein one of a resistor and a capacitor constituting the noise filter is switched by an analog switch.

(6) In the image forming method, a constant current chopping control circuit for controlling a motor, such as a stepping motor, which sequentially rotates an excitation phase and rotates so as to keep a driving current constant, is provided. A control circuit for setting a reference voltage for setting a predetermined current value; detecting a voltage value of a current detecting resistor for detecting a current flowing through the motor; Comparing the output value obtained by the above through a comparing means such as a comparator, and switching and selecting at least two or more time constants between a reference voltage value and a detection voltage value applied to an input portion of the comparator. The current flowing through the motor is turned on based on the comparison result of the simple noise removing means and the comparing means.
Control means for performing / OFF control (chopping control), and switching the time constant of noise removal according to the magnitude of the load driven by the motor.

(7) A storage medium storing a program for realizing the image forming method described in (6).

(8) In the image forming method described in (6), when the load driven by the motor is larger than a predetermined value, a sufficient time constant is selected because noise removal is required. When the load is smaller than a predetermined value and the motor is started, a time constant larger than the time constant is selected.

(9) The image forming method according to the item (6), wherein when the motor is started, the speed is accelerated.

(10) In the image forming method according to the above (6), the noise removing means includes a resistor R and a capacitor C
An image forming method, characterized in that the image forming method comprises:

(11) In the image forming method according to the above (6), the time constant switching selection function is to switch one of a resistor and a capacitor constituting the noise filter by an analog switch. Method.

(12) In an image forming apparatus in which the paper transport drive is performed by a stepping motor, a constant current chopping control for controlling the stepping motor to control the motor rotating sequentially by switching the excitation phase so as to keep the driving current constant. The constant current chopping control circuit includes a reference voltage setting means for setting a predetermined current value and a voltage value of a current detecting resistor for detecting a current flowing through the motor. Voltage detecting means, a comparing means such as a comparator for comparing the output values of the reference voltage setting means and the voltage detecting means, and a reference voltage value applied to an input portion of the comparator and a detected voltage value. At least two or more time constants can be switched and selected. Control means for controlling the current to be turned on / off (chopping control); and detection means for detecting the presence or absence of a sheet on a roller driven by the motor in order to execute sheet conveyance. When the motor starts rotating from a state in which no paper is present on the rollers, the time constant of noise removal is switched to a value larger than a predetermined value, and when the rotation speed matches the rotation speed of a predetermined frequency, An image forming apparatus for performing control for switching to the predetermined value.

(13) In the image forming method in which the paper conveyance drive is performed by a stepping motor, a constant current chopping control for controlling the stepping motor so as to keep the driving current constant by the motor rotating sequentially by switching the excitation phase. A constant current chopping control circuit, wherein the constant current chopping control circuit sets a reference voltage for setting a predetermined current value, and detects a voltage value of a current detection resistor for detecting a current flowing through the motor. And comparing the output value obtained by the voltage detection with the reference voltage via a comparing means such as a comparator, and comparing the reference voltage value and the detected voltage value applied to the input unit of the comparator with each other. At least two or more time constants are switchable and selectable. Te, the current flowing in the motor ON /
The method includes a step of performing OFF control (chopping control) and a step of detecting the presence or absence of a sheet on a roller driven by the motor in order to execute sheet conveyance. When the motor starts rotating, the time constant of noise removal is switched to a value larger than a predetermined value, and when the rotation speed matches the rotation speed of a predetermined frequency, control for switching to the predetermined value is performed. And an image forming method.

(14) A storage medium storing a program for realizing the image forming method described in (13) above.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below.

FIG. 1 is a block diagram showing a configuration example of a conventional chopping control, FIG. 2 is a block diagram showing a configuration example of a typical drive circuit according to the present invention, and FIGS. 3 (a) and 3 (b).
FIG. 4 is a waveform diagram of a current flowing through the motor during the chopping control operation, FIG. 4 is a block diagram of a main part of the embodiment, and FIG.
FIG. 6 is a flowchart showing the control operation of the present embodiment, FIG. 7 is a schematic vertical side view showing the waist configuration of the image forming apparatus according to the present invention, and FIG. It is an explanatory perspective view showing the details of such a paper conveyance device.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

(Embodiment) FIG. 7 is a vertical sectional side view showing the internal structure of an embodiment to which the image forming apparatus of the present invention is applied. The image forming apparatus includes a main body image output unit 10 which is a device for placing and outputting a document image on a recording sheet, a main body image input unit 11 which is a device for reading image data from a document, and an upper part of the main body image input unit 11. The apparatus includes an attached automatic document feeder 12 and a sorter 13 for sorting copy paper discharged from the main body image output unit 10 into a plurality of pins and discharging the copy paper.

This image forming apparatus is, for example, a digital copying machine. The image forming apparatus is a device for reading image data from a document. After being performed, it is stored in the image memory. The image data is transferred to the main body image output unit 10, where the image is reproduced and copied on a recording sheet.

The main body image input unit 11 includes a light source 21 for scanning while irradiating a document stacked on a document table on the upper surface of the input unit.
Is provided. The light source 21 receives a driving force from an optical system motor (not shown) and reciprocates in the left-right direction in FIG. Light generated from the light source 21 is reflected by the stacked originals, and an optical image is obtained. This optical image is transmitted to the CCD 26 via the mirrors 22, 23, 24 and the lens 25. The mirrors 22, 23 and 24 are driven integrally with the light source 21.
The CCD 26 is constituted by an element for converting light into an electric signal, and the transmitted optical image is converted into an electric signal and further converted into a digital signal (image data) by the function of the element.

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

The main body image output unit 10 reads out the image data stored in the image memory, reconverts the digital data into an analog signal, and amplifies it to an appropriate output value by an exposure control unit (not shown). The light is converted into an optical signal by 27. The optical signal is transmitted to the scanner 28 and the lens 2
The light propagates through the mirror 9 and the mirror 30 and irradiates the photosensitive drum 31 to form an electrostatic latent image. The latent image forms an image with toner, is transferred onto a recording paper conveyed in the main body, and is further fixed on the recording paper by a fixing roller 32, where the image data is recorded.
Sent to

The sorter 13 is a device installed on the left side of the main body image output section 10 as shown in FIG. 7, and sorts recording paper output from the main body image output section 10 into a paper discharge tray 33 to discharge paper. Perform the following processing. The discharge tray 33 is controlled by the main body control unit (not shown), and the output recording paper is discharged to an arbitrary discharge tray designated by the control unit.

The paper feed trays 34 and 35 are located at the lower part of the main body.
It is possible to accumulate recording paper to some extent. The control unit conveys the recording paper accumulated from the paper feed trays 34 and 35 and outputs an image. The paper feed deck 36 is a device installed on the left side of the main body image output unit 10, and can store a large amount of recording paper. Paper feed trays 34, 3
As in the case of 5, the recording paper accumulated by the control unit is conveyed and an image is output.

On the left side of the main body image output unit 10, there is provided a manual feed tray 37 which enables the operator to relatively easily feed a small number of types of copy sheets. The manual tray 37 is also used when special recording paper such as OHP sheets, thick paper, and postcard size paper is used.

Paper feed rollers 38, 39, 40, 41, 42
Is a paper transport roller, and each roller plays a role of actually transporting the recording paper when feeding paper for copy output processing. Each paper feed roller is independently connected to a stepping motor as a drive source via a transmission device such as a gear. FIG. 8 shows details of this part.

FIG. 8 is a detailed block diagram of the paper transport device in the image forming apparatus of the present invention. Here, the arrow in the figure indicates the direction in which the paper is actually conveyed.

Reference numeral 801 denotes a stepping motor serving as a driving source of the paper conveying device. As a method of classifying a stepping motor, a classification based on the structure of the motor is generally used. This includes a PM type (Permanent Magnet) in which the rotor is made of permanent magnets.
Type), V rotor made of gear-shaped iron core
R type (Variable Reluctance Ty)
pe), and the rotor portion can be classified into an HP type (Hybrid Type) in which the rotor portion is constituted by a gear-shaped iron core and a magnet. Other classifications of stepping motors include those based on drive windings. The classification based on the drive winding is classified into two-phase, three-phase, five-layer, and the like. Further, the classification by the excitation mode can be classified into one-phase excitation, two-phase excitation, one-two-phase excitation, and the like.

In this embodiment, a two-phase excitation type HR type stepping motor is employed.

Reference numeral 802 denotes a paper transport roller, which has a role of applying a force to and transporting the recording paper to be actually transported. The driving force from the stepping motor 801 is transmitted to the paper conveying roller 802 through a gear, a shaft, or the like. As described above, in the configuration in which the driving force is transmitted by the gear and the transport rollers form a pair with one motor, the load when the paper is not present on the transport rollers is reduced by the thick paper sandwiched between the rollers. In many cases, the load is extremely low as compared with the load at the time of start-up or when the sheet enters the roller.

Reference numeral 803 denotes a paper detection sensor. Also 804
Is a photo-interrupter which plays a role of converting a reaction of the paper detection sensor into an electric signal. Although the paper passes in the direction indicated by the arrow in the figure, a paper detection sensor 803 is provided in front of the paper feed roller. The tip of the paper is the paper detection sensor 80
3, one end of the paper detection sensor 803 is pressed, and the other end closes the light emitting unit and the light receiving unit of the photo interrupter 804.

Paper detection sensor 803 and paper transport roller 802
Is shorter than the paper length of the smallest recording paper that can be used in the image forming apparatus, and if the stepping motor 801 operates normally and the paper feed roller 802 is driven, the paper detection sensor 803 detects the paper. It is designed so that the paper detection is turned off within a certain time.

When the light emitting unit and the light receiving unit of the photo interrupter 804 are closed, the output signal from the photo interrupter 804 changes. The control unit of the image forming apparatus monitors the signal of the photo interrupter 804 at regular intervals,
If there is a change in the output signal, it is determined that paper has been detected.

FIG. 4 is a block diagram showing a main part of an embodiment to which the motor driving device of the present invention is applied. 101 is a stepping motor to be controlled, 102 is a central processing unit (hereinafter referred to as a CP) that outputs a drive signal of the stepping motor.
U), 103 is a drive circuit for supplying a current necessary for rotating the stepping motor, and 104 is a motor control CL.
A timer for generating K, a ROM device 105 storing a motor control program, a RAM device 106 for the CPU to use as a temporary storage area, and a sensor 107 for detecting the presence or absence of a sheet.

First, a stepping motor to be controlled by the motor driving device according to the present invention will be described. The most characteristic of the stepping motor 101 is that the rotation angle changes in proportion to the input pulse and the rotation speed changes in proportion to the input pulse frequency. For this reason, it is possible to control the motor without feeding back the rotation angle and the rotation speed.

In the motor driving device of this embodiment, the CP
U102 has a role of calling a stepping motor control program stored in the ROM device 105 and outputting a phase excitation signal, which is a drive signal of the stepping motor 101, to the drive circuit 103 in accordance with the instructions of the program. That is, a phase excitation signal having a frequency corresponding to the target motor speed is output.

The ROM device 105 is a nonvolatile storage device.

On the other hand, instead of a conventional CPU called a microcomputer, a RISC CPU realizing high speed and low power consumption by reducing the number of instructions and equalizing the instruction length, and a processor specializing in real-time digital signal processing. DS
P and the like are also widespread, and can be realized also in the motor drive device of the present invention.

The ROM device 105 stores a motor control program.
Loaded to U102.

The RAM device 106 is a rewritable storage device for storing the calculation result and temporarily saving the calculation result when the CPU 102 performs the calculation.

In recent years, there is also a CPU in which a ROM and a RAM are integrated in the same package as the CPU. When such a CPU is used, the ROM device and the RAM device can be omitted.

The sensor 107 is a paper detection sensor 80 for determining whether or not a sheet exists on the roller shown in FIG.
3 and a photo interrupter 804.
From this detection result, the CPU 102 can determine the state of the load on the roller. When a sheet is detected, the load is heavy, and when not detected, the load is light.

The above-described motor driving device allows the CPU to control the acceleration / deceleration of the motor as shown in FIG.
The phase excitation switching signal, the excitation signal, and the presence or absence of paper on the roller shaft are detected, and the filter time constant switching signal, which is a main part of the present invention, is controlled based on the detection result. Here, generally, the excitation signal 501 is a signal for permitting a current to flow into the motor, and is a control signal for executing excitation when the motor is rotating or stopped. Further, the phase excitation switching signal 502 is a DM in the CPU.
This is a control signal for switching the current flowing into the motor generated by the arithmetic processing by A or the DSP. The motor drive IC outputs the phase excitation switching signal from 1 CLK to several CLKs. The motor is smoothly accelerated by controlling the phase excitation switching signal to increase its cycle (motor driving state 504). The same applies to deceleration / constant speed driving. Reference numeral 505 denotes a paper detection signal.

In the drive circuit 103, constant current chopping control is implemented by hardware, and the current supplied to the stepping motor 101 is turned on / off in accordance with the phase excitation switching signal 502 from the CPU 102, and the current flowing through the motor is kept constant. The chopping control is performed so that the current becomes the current, and the current is supplied to the stepping motor 101.

The characteristic drive control of the present invention will be described in detail with reference to FIGS.

FIG. 1 is a block diagram showing a part of the conventional chopping control. In FIG. 1, the voltage dividing resistors r1,
r2 is a resistor for setting a predetermined chopping current value, and the divided voltage value is determined by the ratio of the reference voltage to r1 and r2. The driving motor 1008
, A current flows through a driver circuit 1007, and the current value is measured by a current detection resistor R1. The partial pressure value and the detected value are compared and calculated by a comparator 1004, and when the detected value exceeds a preset partial pressure value, chopper ON / OFF control means 1005 prevents a current exceeding a certain value from flowing into the motor. Then, the chopping control is performed on the driver circuit 1007. Here, the driver circuit 1007 is, for example, a MOS FET
The ringing noise is added to the detection value and the divided voltage value by the noise generated at the time of the driver ON / OFF control during the chopper operation, so that an erroneous comparison operation process is not generated. In many cases, a noise filter 1003 mainly composed of CR is configured. If the time constant is too small, the noise cannot be removed,
On the other hand, if it is too large, the timing of comparison with the change in the current actually flowing into the motor is shifted, and FIGS. 3 (a) and 3 (b)
The chopping operation is started from a current value lower than the reference current value as shown in (1), and thereafter, the state gradually approaches the reference current value. In this state, the effective value of the current that actually flows into the motor is smaller than the effective value of the set current that should flow, and the torque during high-speed rotation cannot be sufficiently extracted. Therefore, usually, when determining this time constant, it is adjusted so that the chopping operation is performed stably with the reference current value as shown in FIG. 3B while observing the chopping waveform.

However, with the time constant adjusted as described above, at the time of starting from a state where the load driven by the motor is large or in a high-speed rotation region, high torque can be output and at the same time the load driven by the motor can be output. Unnecessarily high torque is output even when starting from a small state,
It is often found that the torque is oversupplied with respect to the load and inertia connected to the motor. If the torque is output too much,
Start-up noise that exceeds the noise standard is generated, and in the worst case, a strong earthquake may be lost. Therefore, FIG.
By applying the characteristics as in (a) when starting the motor,
This problem can be solved. In FIG. 3A, it is as if the slow start control is applied to the diagram of FIG. 3B which is an appropriate chopping control, and the current actually flowing into the motor gradually increases. Therefore, at the stage where the motor starts to rotate by the step angle, the torque is relatively low because the current value is small, and the motor starts to rotate smoothly by that amount, and thereafter, a prescribed current value flows over time. As a result, the load to be driven is light and rises smoothly at the time of startup that does not require a large torque, so that smooth acceleration driving can be performed without generating annoying startup noise. After that, when the rotation speed becomes high,
The filter time constant is changed so that chopping control as shown in (b) can be performed. Here, even at the time of high-speed rotation, with the control as shown in FIG. 3A, the pull-out torque characteristic is lower by about 10% to 20% (state of FIG. I know there isn't. Also, when the driving load is large, a high torque is required, so that the control as shown in FIG.

FIG. 2 is a block diagram showing a control circuit capable of switching the time constant of the above-mentioned filter.
The noise filter 2001 is composed of at least two or more switching circuits.
In the R circuit, the resistance R is switched, but the capacitor C may be switched, or the time constant may be switched by another circuit. As an example of the switching circuit 2002, an analog switch and a digitizer are used.
By performing FF, it is possible to switch the time constant of the filter.

The above operation will be described with reference to the flowchart of FIG.

At the start of motor rotation, first, in step S6
At 01, the motor is set to the excited state by the excitation signal control.
Next, in step S602, it is detected whether or not paper is present on the transport roller driven by the motor. If paper is not detected, the process proceeds to step S603, and an appropriate time constant is set when the motor is started under light load. Control is performed so that 1 is selected. At this time, the operation order of steps S601 and S602 may be reversed. At this stage, the phase excitation switching signal 502 for controlling the acceleration is supplied to the motor drive circuit 103.
The stepping motor 101 performs a smooth acceleration operation under the filter time constant 1 (steps S604 and S605). Thereafter, the filter time constant is switched to 2 when the motor rotates at high speed and at constant speed. Stepping motor 101 has filter time constant 2
Under this condition, the rotary drive is continued while having sufficient pull-out characteristics. On the other hand, if paper is detected in step S602, it is determined that the acceleration operation is under a heavy load, and a filter time constant 2 is selected. As a result, the acceleration operation is performed while having sufficient pull-out characteristics, and then the rotational drive is continued (step S611).

[0056]

According to the present invention, in a motor for driving an image forming apparatus, when the motor is started under a light load condition,
By increasing the time constant of the filter, pseudo soft start control is performed as shown in FIG. 3 (a), noise and vibration are suppressed by generating a gentle torque, and a load larger than a predetermined load is applied to the motor. At the time of start-up when it is determined to be applied, or when the motor is in a steady rotation state, the time constant of the filter is controlled so as to be reduced to a value necessary and sufficient for noise removal, thereby controlling the motor. This has the effect that the torque output can be sufficiently exhibited.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of a conventional chopping control.

FIG. 2 is a block diagram showing an example of filter selection control constituting a typical drive circuit according to the present invention.

FIGS. 3A and 3B are waveform diagrams of a current flowing through a motor during a chopping control operation.

FIG. 4 is a block diagram of a main part configuration of the present embodiment.

FIG. 5 is a correlation state diagram of a control signal.

FIG. 6 is a flowchart illustrating a control operation according to the present embodiment.

FIG. 7 is a longitudinal sectional side view showing a main part configuration of the image forming apparatus according to the present invention.

FIG. 8 is an explanatory perspective view showing details of a paper transport device according to the present invention.

[Explanation of symbols]

 Reference Signs List 101 stepping motor 102 CPU 103 drive circuit 104 timer 105 ROM 106 RAM 107 sensor 1001 voltage dividing resistance value r1 1002 voltage dividing resistance value r2 1003, 2001 noise filter 1004 comparison means (comparator) 1005 chopper ON / OFF control means 1006 current detection resistance R1 1007 driver circuit

Claims (14)

[Claims] 1. An image forming apparatus having a control system with a constant current chopping control circuit for controlling a motor such as a stepping motor that rotates while sequentially switching an excitation phase so as to keep a drive current constant, wherein the constant current chopping control is performed. The circuit includes a reference voltage setting unit for setting a predetermined current value, a voltage detection unit for detecting a voltage value of a current detection resistor for detecting a current flowing through the motor, and the reference voltage setting unit. A comparing means such as a comparator for comparing an output value with the voltage detecting means; and at least two or more time constants can be switched and selected between a reference voltage value applied to an input portion of the comparator and a detected voltage value. Noise removing means, based on a comparison result of the comparing means,
An image forming apparatus comprising: a control unit that controls ON / OFF (chopping control) of a current flowing through a motor, and controls switching of a time constant of noise removal according to the magnitude of a load driven by the motor. 2. When the load driven by the motor is larger than a predetermined value, a sufficient time constant is selected by requiring noise removal, while the load is smaller than the predetermined value.
2. The image forming apparatus according to claim 1, wherein a time constant larger than the time constant is selected when the motor is started. 3. The image forming apparatus according to claim 2, wherein when the motor is started, the speed is accelerated. 4. The image forming apparatus according to claim 1, wherein the noise removing unit is a noise filter including a resistor R and a capacitor C. 5. The image forming apparatus according to claim 1, wherein the time constant switching selection function switches one of a resistor and a capacitor constituting the noise filter by an analog switch. 6. An image forming method according to claim 1, further comprising a control system having a constant current chopping control circuit for controlling a motor such as a stepping motor that rotates by sequentially switching excitation phases so as to keep a drive current constant. In the circuit, a step of setting a reference voltage for setting a predetermined current value; a step of detecting a voltage value of a current detection resistor for detecting a current flowing through the motor; and A step of comparing the obtained output value via a comparing means such as a comparator, and at least two or more time constants between a reference voltage value and a detection voltage value applied to an input portion of the comparator can be switched and selected. The current flowing to the motor is turned on / off based on the comparison result of the noise removing means and the comparing means.
Control means for performing FF control (chopping control),
Controlling switching of a time constant of noise removal according to the magnitude of a load driven by the motor. 7. A storage medium storing a program for realizing the image forming method according to claim 6. 8. The image forming method according to claim 6, wherein
When the load driven by the motor is larger than a predetermined value, noise elimination is necessary and a sufficient time constant is selected.On the other hand, when the load is smaller than a predetermined value and the motor is started, the An image forming method, wherein a time constant larger than a time constant is selected. 9. The image forming method according to claim 6, wherein
The image forming method according to claim 1, wherein when the motor is started, the speed is accelerated. 10. The image forming method according to claim 6, wherein said noise removing means is a noise filter including a resistor R and a capacitor C. 11. The image forming method according to claim 6, wherein the time constant switching selection function switches one of a resistor and a capacitor constituting the noise filter by an analog switch. 12. A constant current chopping control circuit for controlling a stepping motor to control the stepping motor so that the motor rotates by sequentially switching the excitation phase so as to keep the driving current constant. Wherein the constant current chopping control circuit includes a reference voltage setting means for setting a predetermined current value and a voltage value of a current detecting resistor for detecting a current flowing through the motor. Voltage detection means, comparison means such as a comparator for comparing output values of the reference voltage setting means and the voltage detection means, and at least a reference voltage value applied to an input portion of the comparator and a detection voltage value. Two or more time constants switchable and selectable noise removing means, based on a comparison result of the comparing means,
Control means for ON / OFF control (chopping control) of a current flowing through the motor; and detection means for detecting the presence or absence of a sheet on a roller driven by the motor in order to execute sheet conveyance. When the motor starts rotating from the state where the paper does not exist on the roller according to the detection result,
An image forming apparatus, comprising: switching a time constant of noise removal to a value larger than a predetermined value; and performing control to switch to the predetermined value when the number of rotations matches a number of rotations of a predetermined frequency. 13. An image forming method in which a paper transport drive is performed by a stepping motor, a constant current chopping control circuit for controlling a stepping motor to control a motor rotating by sequentially switching excitation phases so as to maintain a constant drive current. The constant current chopping control circuit sets a reference voltage for setting a predetermined current value, and detects a voltage value of a current detecting resistor for detecting a current flowing through the motor. Steps and
Comparing the reference voltage and an output value obtained by the voltage detection via a comparing means such as a comparator; and at least two or more detection voltage values between the reference voltage value and the detection voltage value applied to the input section of the comparator. The current flowing through the motor is turned ON / OF based on the comparison result of the noise elimination means for which the time constant can be switched and selected and the comparison means.
F control (chopping control) and a step of detecting the presence or absence of a sheet on a roller driven by the motor in order to execute the sheet conveyance. When the motor starts rotating, the time constant of noise removal is switched to a value larger than a predetermined value, and when the rotation speed matches the rotation speed of a predetermined frequency, control for switching to the predetermined value is performed. And an image forming method. 14. A storage medium storing a program for realizing the image forming method according to claim 13.