JP2003215870A - Image forming device - Google Patents

Abstract

(57) Abstract: A transport drive system for transporting the same print medium through an image forming system, and a feed drive system for transporting the print media from a print medium storage device to a transport unit driven by the transport drive device. With
When belonging to both systems, it is possible to make the speed of both systems the same, eliminate the pushing and pulling of the print medium, do not affect the image forming system by the speed change, and perform stable image formation on the print medium. An image forming apparatus is provided. SOLUTION: A transport driving device 11a and a feeding driving device 12
a detecting means 26 and 27 for detecting the driving speed of the driving means of at least one of the driving devices, and driving both of them by the speed detected by the detecting means 26 and 27. Speed control means 19 for controlling the speed of the means 17 and 22;
9 generates a drive signal to drive both drive units 17 and 22
An image forming apparatus for transmitting the image data to both the driving devices 11a and 12a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, in particular, an image forming apparatus of a form in which a feeding / transporting speed of a print medium is controlled.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus, a print medium is conveyed from a paper feeding unit storing the print medium to an image forming system at the time of image formation, and a toner image formed by the image forming system is transferred onto the print medium. After transfer, the paper is fixed and ejected. An image is formed on the print medium by this series of operations.

A feeding motor for feeding a printing medium from a paper feeding unit storing the printing medium and a feeding motor for feeding the printing medium into the image forming system are well known phases in the past. -Each motor was independently controlled to a predetermined speed by locked loop (PLL) control.

[0004]

However, in the image forming apparatus as described above, the time required for two different motors to rotate at a constant speed, the control timing of each motor, the control amount, and the sheet passing at that time. Depending on the situation, the distance for feeding and conveying the print medium may differ.

Therefore, when a plurality of print media are continuously fed and conveyed and stopped, the differences are piled up. As a result, the print media are overlapped or separated from each other, and the print media are pushed or pulled due to the difference in speed. I had to do it.

Further, when the image formation is performed in a state where the print medium is disturbed, the traveling speed of the print medium is not stable during the image formation. Therefore, even if the image formation is performed at a predetermined timing for each color, In the image formed by, the images of the respective colors do not match. Therefore, it has also been a cause of outputting an image with low image quality.

The present invention has been made in view of the above problems, and an object of the present invention is to convey the same print medium with a conveyance drive system for conveying an image forming system and a printing system. When belonging to both systems, a feeding drive system that feeds from the medium storage device to the transport section driven by the transport drive device,
To provide an image forming apparatus capable of performing stable image formation on a print medium by matching the speeds of both systems, eliminating pushing and pulling of the print medium, and not affecting the image forming system by the influence of speed change. It is in.

[0008]

Therefore, in the present invention, the above object is achieved by providing an image forming apparatus shown in any of the following items (1) to (11). Is.

(1) A transport drive device for transporting the image forming system at a predetermined process speed while restraining the print medium, and a print medium located upstream of the image forming system and transported from the print medium storage device. In an image forming apparatus including a feeding drive device that feeds to a conveyance unit driven by a driving device, the conveyance drive device and the feeding drive device are provided with the same type of driving means, and at least one of the driving devices. And a speed control means for controlling the speed of both drive means by the speed detected by the detection means, the speed control means generating a drive signal. An image forming apparatus, characterized by transmitting to both drive means to drive both drive devices.

(2) The image forming apparatus according to item (1), wherein the detecting means for detecting the driving speed of the driving means is provided in the driving means for driving at least one of the driving means.

(3) The image as described in the above item (1), wherein the detecting means for detecting the driving speed of the driving means is provided in at least one of the transport driving device and the feeding driving device. Forming equipment.

(4) The image forming apparatus as described in the above item (1), wherein the same type of driving means of the conveyance driving device and the feeding driving device is a stepping motor.

(5) The image forming apparatus as described in the above item (1), wherein the same type of driving means for the transport driving device and the feeding driving device is a DC brushless motor.

(6) The image forming apparatus as described in the item (1), wherein a high-speed product-sum calculation element is used as the speed control means.

(7) A digital signal processor is used as the speed control means.
The image forming apparatus according to the item.

(8) The detecting means for detecting the drive speed of the DC brushless motor detects the pattern magnetized on the rotor of the DC brushless motor with a ferromagnetic magnetic effect type sensor, and drives the DC brushless motor. The image forming apparatus according to (5) above, which detects

(9) The detecting means for detecting the driving speed of the driving means detects the driving speed of the driving means by the output of an encoder mounted in the vicinity of the driving means. ) Or the image forming apparatus according to (5).

(10) The speed control means has an error detection means for comparing an output cycle of the drive speed detection means in a predetermined section with a reference cycle and detecting an error therebetween, and the error detection means The image forming apparatus according to item (1), wherein the speed of the driving unit is controlled based on the output of the unit.

(11) An image forming apparatus according to the item (1), further comprising a storage unit, wherein the speed control unit is a type of print medium before printing at the time of printing,
An image forming apparatus, characterized in that a timing at which a speed fluctuation occurs and a speed fluctuation amount are respectively stored in the storage means, and a speed control of the drive means is corrected based on the stored data.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the invention will be described below with reference to a plurality of examples.

(First Embodiment) First, a first embodiment will be described with reference to FIGS.

FIG. 1 is a diagram of an image forming apparatus according to the first embodiment. In FIG. 1, 1 is a scanner unit,
2 is a rotary polygon mirror, 3 is a cartridge, 4 is a photoconductor, 5 is a developing sleeve, 6 is a Y developing cartridge, 7 is an M developing cartridge, 8 is a C developing cartridge, 9 is a BK developing cartridge, 10 is a transfer roller, 11 Is a conveyor belt which is a conveyor, 11a is a drive roller which is a conveyor drive device, 12 is a paper feed unit which is a print medium storage device, 1
Reference numeral 2a is a sheet feeding roller which is a feeding drive device, 13a is a print medium mounted in the sheet feeding unit 12, 14 is a fixing device, 15 is a fixing roller, and 16 is a heater roller.

The scanner unit 1 comprises a semiconductor laser (not shown) and a rotary polygon mirror 2.

The cartridge 3 stores the developer and also the waste toner generated when the excess toner on the photoconductor 4 is cleaned.

The developing sleeve 5 develops the electrostatic latent image on the surface of the photoreceptor 4 into a toner image.

Reference numerals 6, 7, 8, and 9 collectively denote the cartridge 3, the photoconductor 4, and the developing sleeve 5 to form a developing device (hereinafter referred to as a developing cartridge), which are yellow Y, magenta M and cyan C, respectively. , A black BK developing cartridge. The order of the developing cartridges is not particularly limited, and the order can be changed.

The transfer roller 10 transfers the toner image on the photosensitive member 4 developed by each color developing cartridge 6-9 to a print medium.

The conveyor belt 11 is composed of an endless belt for conveying the print medium.

An image forming system is composed of the color developing cartridges 6 to 9 and the transfer roller 10.

The fixing device 14 is for fixing the toner image on the print medium to the print medium, and the fixing roller 1
5. A heater roller 16 for heating the fixing device for fixing the toner image on the print medium is provided.

FIG. 2 is a schematic diagram showing the feeding system and the print medium carrying system in the first embodiment.

13b is a print medium being conveyed, 17 is a motor which is a drive means for driving the conveyor belt 11 via the drive roller 11a, 18 is a CPU, and 19 is a motor controller which is a speed control means.

20 is a motor driver for driving the motor 17 of the drive roller 11a, and 21 is the feeding roller 1
A motor driver for driving the motor 22 of 2a, 2
Reference numeral 2 is a motor that is a driving means of the feeding roller 12a.

In FIG. 2, an encoder that outputs a signal in synchronization with the rotation of the motor 17 is attached to the shaft of the motor 17.

The rotation speed of the motor 17 can be detected by detecting how many times the encoder signal is detected at regular intervals.

Therefore, the rotation speed can be detected more accurately with a higher-definition encoder.

In addition, speed detection means such as an optical sensor that outputs 1 PULSE per revolution of the motor 17 may be used to detect the rotation speed.

In this case, the rotation speed of the motor can be detected by measuring the time between PULSE.

The CPU 18 controls the timing of starting and stopping the driving of the motors 17 and 22.

A high-speed multiply-accumulate operation element and a digital signal processor (hereinafter referred to as DSP) are used for the motor controller 19 which sends control signals to the motor drivers 20 and 21.
The speed of the motors 17 and 22 is controlled.

In this embodiment, a DSP is used.

The motor 22 of the feeding roller 12a can be driven to feed the print medium 13a stored in the paper feeding unit 12 to the conveyor belt 11.

In this embodiment, the motors 17 and 2 are especially used.
2 adopts a DC brushless motor.

The operation of the image forming apparatus having the above structure will be described.

When receiving the image data, the CPU 18 first
Sends a drive start signal to the motor controller 19.

The motor controller 19 sends a drive signal to each DC brushless motor 17, 22.

Then, the DC brushless motors 17, 22
During driving, the rotation speed information is sent to the motor controller 19 by an encoder (other speed detecting means may be used) attached to the DC brushless motor 17.

The motor controller 19 performs feedback control so that the rotation speeds of the DC brushless motors 17 and 22 are constant.

A drive signal for performing this feedback control is transmitted from the motor controller 19 to each DC brushless motor 17, 22.

When the DC brushless motor 17 reaches the target rotation speed, the motor controller 19 causes the CP
Send a motor ready signal to U18.

When the CPU 18 receives the motor ready signal, the CPU 18 starts the paper feeding operation and conveys the print medium 13a mounted in the paper feeding unit 12 to the conveyor belt 11 by the paper feeding roller 12a.

The print medium 13b being conveyed to the conveying belt 11 is adsorbed by the conveying belt 11 rotating at the image forming process speed Vp, and at the process speed Vp,
The sheet is conveyed to the front edge of the BK developing cartridge 9, that is, the leading portion of the image forming system.

Here, the printing medium 13b being conveyed is BK
The BK toner image formed on the photoconductor 4 in the developing cartridge 9 is transferred by the transfer roller 10.

After that, the toner image of C is transferred onto the print medium 13b being conveyed by the C developing cartridge 8 in the conveying order, and the M toner image and the Y toner image are successively conveyed to the print medium 1 being conveyed.
The toner images of full color are finally formed on the printing medium 13b which is being conveyed.

When the transfer of the Y toner image by the Y developing cartridge 6 at the most downstream side of the image forming system is completed, the front end of the print medium 13b being conveyed is conveyed at the process speed Vp.
Then, the image forming system is removed, and the fixed paper is discharged.

Next, a method for controlling the feeding and conveying speed of the print medium in this image forming apparatus will be described with reference to FIG.

FIG. 3 is a diagram showing a motor control system.
Is a ferromagnetic magnetoresistive effect type sensor element (hereinafter referred to as MR sensor) which is a ferromagnetic magnetic effect type sensor, 25 is a waveform converter, and M is composed of the MR sensor 24 and the waveform converter 25.
An R sensor type detection means is configured.

Reference numeral 26 is a disk (code wheel) having slits at equal intervals along the circumference, and 27 is a photo interrupter. The disk 26 and the photo interrupter 27 constitute an encoder type detecting means.

28 is a signal selector, 29 is a counter inside the motor controller (DSP) 19, 30 is a memory,
Reference numeral 31 is a counter table, and 32 is a paper type detection unit for detecting the type of the print medium 13a mounted on the paper feeding unit 12.

S1, S2 and S3 are speed detection signals.

The configuration of the motor controller 19 is as follows.
As shown in FIG. 3, the two motor controllers have a CPU
It is also possible to perform the same control from 18.

The motor controller 19 using the DSP communicates with the CPU 18, and the motors 17 and 22 are PWM-controlled via the motor drivers 20 and 21.
Control the rotation speed.

By performing the feedback and feedforward control using the DSP, it is possible to control the rotation speed that is hardly influenced by the load fluctuation of the motor 17 and the motor 22.

The drive motor 17 of the drive roller 11a is controlled by the motor driver 20.

The MR sensor 24 uses a pattern in which the rotor is evenly magnetized as Sin corresponding to the rotation speed of the rotor.
It can be read as a waveform.

The motor controller 19 includes the waveform converter 2
5 rectangular pulse wave (eg 500 pulses / rotation)
Based on the output signal S1 of the MR sensor 24 converted into
Controls by detecting the rotation speed of the motor.

Alternatively, the rotation speed of the motor can be detected by the FG pattern formed near the rotor.

Further, in order to detect the rotation speed of the motor 17 outside the motor, a disk 26 having slits at equal intervals along the circumference and a photo interrupter (light transmission type sensor).
An encoder composed of 27 is provided.

Regarding the encoder, in addition, a reflective optical system, an encoder for reading a magnetic pattern formed in a disc shape, and the like are used.

The photo interrupter 27 is arranged so as to sandwich the disc 26 of the encoder. When the light of the photo interrupter passes through the slit of the disc, the rotation speed detection signal S3.
Becomes LOW level.

Therefore, when the motor rotates, the disk 26 provided on the shaft of the drum rotates, and slits at equal intervals along the circumference are sequentially sent between the light emitting and light receiving elements of the photo interrupter 27.

Therefore, the speed detection signal S3 has a pulse-like waveform, and the speed can be detected by the pulse period.

Any of the MR sensor 24, the MR sensor system of the waveform converter 25, the disk 26, and the encoder system of the photo interrupter 27 may be used to detect the rotation speed.

It is sufficient to use either one as the rotation speed detecting means.

In this embodiment, the MR sensor system and the encoder system are selected by the signal selecting means 28.

The memory 30 is internally provided with a counter table 31 which stores a set count value Ct defined for each type of print medium.

The set count value Ct stored in the counter table 31 is the signal output from the speed detecting means by the counter 29 within a fixed time when the print medium is conveyed to the image forming system at the process speed Vp. This is the value to be counted.

For example, when the print medium is thick paper or OHT, the set count value Ct stored in the counter table 31 is smaller than that of plain paper because the process speed is slow.

FIG. 4 shows an example of the speed detection signal S2 from the encoder or MR sensor.

Ct is a set count value, and Cs is a detected count value.

The motors 17 and 22 are controlled based on this speed detection signal S2.

First, the set count value Ct corresponding to the paper type detected by the paper type detection unit 32 in advance is read from the counter table 31 to the CPU 18.

The CPU 18 sends this set count value Ct to the motor controller 19.

In the motor controller 19, the speed detection signal S from the encoder or MR sensor within a fixed time
2 is counted by the counter 29.

The count value Cs thus detected is
The set count value Ct read from the counter table 31 is compared, and if the detected count value Cs is smaller, an acceleration signal (FIG. 4A) is output, and if it is larger, a deceleration signal is output (FIG. 4B). It is transmitted to the drivers 20 and 21, and the driving speed of the motors 17 and 22 (hereinafter, also referred to as rotation speed)
To control.

The acceleration / deceleration of the motors 17 and 22 can be performed by adjusting the electric power supplied to the motors.

In this case, P for driving the motors 17 and 22
The speed is controlled by adjusting the DUTY of the WM.

That is, if the detected count value Cs is smaller (the motor is slower than the specified speed), the PWM
DUTY is increased to accelerate the motors 17 and 22, and when the detected count value Cs is larger (the motor is faster than the specified speed), the DUTY of the PWM is decreased and the motor 1
7 and 22 are decelerated.

Before the print medium 13b being conveyed enters the conveyance of the image forming system, the number of rotations of the motor 17 is almost constant, the rotation speed detection signal S2 has a constant cycle, and is detected by the counter 29. The count value Cs also becomes the same as the set count value Ct (in the steady state).

On the other hand, when the print medium 13b being conveyed plunges in, the load on the motor 17 increases, and the rotation speed of the motor 17 slows for a moment.

Therefore, the cycle of the rotation speed detection pattern becomes long, and the pulse cycle of the rotation speed detection signal S2 becomes long.

Then, the count value Cs of the counter 29
Is less.

When it is determined that the detected count value Cs is less than the set count value Ct, the motor controller 19 sends an acceleration signal to the motor driver 20.

At this time, the acceleration signal is also transmitted to the motor driver 21.

Then, the motors 17 and 22 are simultaneously accelerated.

On the contrary, when the print medium 13b being conveyed comes out of the conveyance of the image forming system, the rotation of the motor 17 becomes faster.

At this time, similarly, the motor controller 19
Transmits a deceleration signal to the motor drivers 20 and 21.

With this series of controls, the motors 17 and 22 are not affected by the progress of the print medium and can always maintain the same rotational speed, and it is possible to carry the paper without pulling or pushing the print medium. .

That is, stable image formation can be performed.

(Second Embodiment) Next, a second embodiment will be described with reference to FIGS.

FIG. 5 is a schematic diagram showing a feeding system and a print medium carrying system in the second embodiment.

The configuration of the image forming apparatus of this embodiment is as follows.
Since the configuration is almost the same as that of the image forming apparatus according to the first embodiment, the same components are designated by the same reference numerals and detailed description thereof will be omitted.

In FIG. 5, 33 is a drive roller 11a.
Motor driver (for stepping motor) for driving the motor 35, 34 is a motor driver (for stepping motor) for driving the motor 36 of the feeding roller 12a, and 35 is for driving the conveyor belt 11. A drive source motor (stepping motor) 36 is a motor (stepping motor) for the feeding roller 12a.

An encoder for outputting a signal in synchronization with the rotation of the motor 35 is attached to the shaft of the motor 35.

The rotation speed of the motor 35 can be detected by detecting how many times the encoder signal is detected at regular intervals.

Therefore, the rotation speed can be detected more accurately with a higher-definition encoder.

In addition, one PULS per one rotation of the motor.
An E-output optical sensor or the like may be used.

In this case, the rotation speed of the motor 35 can be detected by measuring the time between PULSE.

The CPU 18 controls the timing of starting and stopping the driving of the motors 35 and 36.

For the motor controller 19 which sends control signals to the motor drivers 33 and 34, a high-speed product-sum calculation element and a digital signal processor (DSP) are used.
The speed of the motors 35 and 36 is controlled.

By driving the motor 36, the print medium 13a stored in the paper feeding unit 12 is transferred to the conveyor belt 1.
You can feed up to 1.

In the present embodiment, especially the motors 35, 3
6 adopts a stepping motor.

FIG. 6 is a diagram showing a motor control system.
The motor controller 19 using P communicates with the CPU 18, and the PULS is performed via the motor drivers 33 and 34.
The E speed control controls the rotation speeds of the motor 35 and the motor 36.

By performing the feedback and feedforward control using the DSP, it is possible to control the rotation speed that is hardly influenced by the load fluctuations of the motors 35 and 36.

The motor 35 is controlled by the motor driver 33.

The motor controller 19 detects and controls the rotation speed of the motor 35 based on the speed detection signal S3.

In order to detect the rotation speed of the motor 35, the motor 35 is provided with an encoder composed of a disk 26 having slits at equal intervals along the circumference and a photo interrupter (light transmission type sensor) 27. .

As for the encoder, a reflective optical system, a disc-shaped magnetic pattern reading device, or the like may be used.

The photo interrupter 27 is arranged so as to sandwich the disk 26 of the encoder. When the light of the photo interrupter 27 passes through the slit of the disk 26, the rotation speed detection signal S3 becomes LOW level.

Accordingly, when the motor 35 rotates, the disk 26 provided on the shaft of the drum rotates, and the slits at equal intervals along the circumference of the disk 26 are sequentially arranged in the photo interrupter 27.
Is sent between the light emitting element and the light receiving element.

Therefore, the speed detection signal S3 has a pulsed waveform, and the speed can be detected by the pulse period.

The memory 30 is internally provided with a counter table 31 which stores a set count value Ct defined for each type of print medium.

The set count value Ct stored in the counter table 31 is the signal output from the speed detecting means by the counter 29 within a fixed time when the print medium is conveyed to the image forming system at the process speed Vp. This is the value to be counted.

For example, when the print medium is thick paper or OHT, the process speed is slow and the set count value Ct stored in the counter table 31 is smaller than that of plain paper.

FIG. 7 shows the speed detection signal S3 from the encoder.
For example:

The motors 35 and 36 are controlled based on this speed detection signal S3.

First, the set count value Ct corresponding to the paper type detected in advance by the paper type detection unit 32 is read from the counter table 31 to the CPU 18.

The CPU 18 sends this set count value Ct to the motor controller 19.

In the motor controller 19, the counter 29 counts the speed detection signal S3 from the encoder (or MR sensor) within a fixed time.

The count value Cs thus detected is
The set count value Ct read out from the counter table 31 is compared, and if the detected count value Cs is smaller, an acceleration signal (FIG. 7A) is output, and if it is larger, a deceleration signal is output (FIG. 7B). It transmits to the drivers 33 and 34 and controls the drive speed of the motors 35 and 36.

The acceleration / deceleration of the motors 35 and 36 can be performed by controlling the frequency of the phase excitation switching signal of the motors.

That is, when the rotation speed is slowed, the frequency of the phase excitation switching signal is lowered, and conversely, when the rotation speed is increased, the frequency of the phase excitation switching signal is increased to control the rotation speed of the motor.

Before the print medium 13b being conveyed enters the conveyance of the image forming system, the rotation speed of the motor 35 is substantially constant, and the rotation speed detection signal S3 has a constant cycle and is counted by the counter 29. The count value Cs also becomes the same as the set count value Ct (in the steady state).

On the other hand, when the print medium 13b being conveyed plunges in, the load on the driving motor 35 increases, and the motor 3 is momentarily stopped.
The rotation speed of 5 becomes slow.

Therefore, the cycle of the rotation speed detection pattern becomes long, and the pulse cycle of the rotation speed detection signal S3 becomes long.

Therefore, the count value Cs of the counter 29 is
Is less.

When it is determined that the detected count value Cs is less than the set count value Ct, the motor controller 19 sends an acceleration signal to the motor driver 33.

At this time, the acceleration signal is also transmitted to the motor driver 34.

Then, the motors 35 and 36 are simultaneously accelerated.

On the contrary, when the print medium 13b being conveyed comes out of the conveyance of the image forming system, the rotation of the motor 35 becomes faster.

At this time, similarly, the motor controller 19
Sends a deceleration signal to the motor drivers 33 and 34.

With this series of controls, the motors 35 and 36 are not affected by the progress of the print medium and can always maintain the same rotation speed, and it is possible to carry the paper without pulling or pushing the print medium. .

In other words, stable image formation can be performed.

(Third Embodiment) Next, a third embodiment will be described with reference to FIGS.

FIG. 8 is a block diagram showing the control system of the conveyance drive motor of the image forming system and the drive motor of the feeding system in the third embodiment.

The structure of the image forming apparatus of this embodiment is as follows.
Since the configuration is almost the same as that of the image forming apparatus according to the second embodiment, the same reference numerals are given to the same configurations and detailed description thereof will be omitted.

In FIG. 8, 37 is a motor 35, 36.
Is a memory that is a storage unit for storing the rotation speed information of from the start of printing to the end of printing.

In this embodiment, the motor controller 19 constitutes error detecting means.

An encoder that outputs a signal in synchronization with the rotation of the motor 35 is attached to the shaft of the motor 35.

The rotation speed of the motor 35 can be detected by detecting how many times the encoder signal is detected at regular intervals.

Therefore, the rotation speed can be detected more accurately with a higher-definition encoder.

In addition, one PULS per one rotation of the motor
An E-output optical sensor or the like may be used.

In this case, the rotation speed of the motor 35 can be detected by measuring the time between PULSE.

As the motor controller 19 which sends control signals to the motor drivers 33 and 34, a high-speed product-sum calculation element and a digital signal processor (DSP) are used.

By driving the motor 36, the print medium 13a stored in the paper feeding unit 12 is transferred to the conveyor belt 1.
You can feed up to 1.

In this embodiment, a stepping motor is adopted as the motor 35, 36.

As the memory 37, the internal memory of the DSP or the CPU or the dedicated external memory is used.

FIG. 8 is a diagram showing a motor control system.
The motor controller 19 using P communicates with the CPU 18, and the PULS is performed via the motor drivers 33 and 34.
The E speed control controls the rotation speeds of the motor 35 and the motor 36.

By performing the feedback and feedforward control using the DSP, it is possible to control the rotational speed that is not easily influenced by the load fluctuations of the motor 35 and the motor 36.

The motor 35 is controlled by the motor driver 33.

The motor controller 19 detects and controls the rotation speed of the motor 35 based on the speed detection signal S3.

In order to detect the rotation speed of the motor 35, the motor 35 is provided with an encoder including a disk 26 having slits at equal intervals along the circumference and a photo interrupter (light transmission type sensor) 27. .

As for the encoder, a reflective optical system, a disc-shaped magnetic pattern reading device, or the like may be used.

The photo interrupter 27 is arranged so as to sandwich the disk 26 of the encoder. When the light of the photo interrupter 27 passes through the slit of the disk 26, the rotation speed detection signal S3 becomes LOW level.

Therefore, when the motor 35 rotates, the disk 26 provided on the shaft of the drum rotates, and the slits at equal intervals along the circumference of the disk 26 are sequentially arranged in the photo interrupter 27.
Is sent between the light emitting element and the light receiving element.

Therefore, the speed detection signal S3 has a pulse-like waveform, and the speed can be detected by the pulse period.

The memory 30 is internally provided with a counter table 31 which stores a set count value Ct defined for each type of print medium.

The set count value Ct stored in the counter table 31 is the signal output from the speed detecting means by the counter 29 within a fixed time when the print medium is conveyed to the image forming system at the process speed Vp. This is the value to be counted.

For example, when the print medium is thick paper or OHT, the process speed is slow and the set count value Ct stored in the counter table 31 is smaller than that of plain paper.

Next, FIG. 9 shows an example of the speed detection signal S3 from the encoder.

T represents the time from the start of printing.

L is a shift amount, which is a difference (Ct-Cs) between the detection signal (set count value Ct) in the steady state and the count value Cs sampled at that time.

Ltp is a positive threshold value of the shift amount l,
ltm is a negative threshold value of the shift amount l.

The motors 35 and 36 are controlled based on this speed detection signal S3.

First, the data of the rotation speed of the motor 35 from the start of printing the first sheet to the end of printing is detected and stored in the memory 37.
To store.

The data to be stored is the type of print medium, the timing t, the shift amount l, etc., and may include the count value Cs, etc., if necessary.

Then, when the rotation speed of the motor 35 greatly changes as compared with the steady state, that is, when the deviation amount 1 exceeds the threshold value ltp or falls below the threshold value itm (when the speed variation is detected). ), The amount of deviation l from the timing t and the set count value Ct is calculated by the motor controller 19 and stored in the memory 37.

Then, at the time of printing of the next print medium, the motor rotation drive for correcting the calculated deviation amount l of the speed only at the timing t when the deviation amount l exceeds the threshold value ltp or falls below the ltm. By adding the signal, it is possible to suppress the speed fluctuation when the print medium plunges.

This control is adopted when the print medium is the same type based on the print medium determined by the paper type detection unit 32.

Here, first, the data of the rotation speed of the motor 35 from the start of printing of the first sheet to the end of printing are stored in the memory 37, but only the data at the time of speed fluctuation detection may be stored.

Next, the control for storing only the data at the time of detecting the speed fluctuation in the memory 37 will be described with reference to the flowchart of FIG.

After the start of printing (s101), the driving of the motors 35 and 36 is started at a predetermined timing (s102).

At the same time, the counter 29 starts counting the rotation speed signals of the motors 35 and 36 (s1.
03).

While the motor is being driven, this count is advanced, and a change more than the rotation unevenness peculiar to the motor occurs with respect to the set count value Ct of the cycle during steady rotation (s104).
In this case, the type of print medium at that time and the timing t
And the shift amount 1 are stored in the memory 37 (s105).

Then, when the motor is driven after the start of the next image formation, the type of the print medium at that time, the timing t, from the memory 37 are set so as to cancel the change in the rotation that has occurred in the previous printing in advance. The shift amount 1 is read out, and the motor drive signal is corrected (S106).

The actual acceleration / deceleration of the motors 35 and 36 can be performed by controlling the frequency of the phase excitation switching signal of the motors 35 and 36.

The rotation speed of the motors 35 and 36 is controlled by lowering the frequency of the phase excitation switching signal when lowering the rotation speed and conversely increasing the frequency of the phase excitation switching signal when increasing the rotation speed. There is.

When the motors 35 and 36 are DC motors, similar speed control can be realized by PWM duty control or the like.

With the above control, it is possible to predict the load fluctuation of the driving means (motor) that occurs at the time of image formation, and to perform the motor drive control while suppressing the speed fluctuation of the print medium conveyance, and to pull or push the print medium. Thus, it is possible to stably convey the print medium without causing the problem.

In other words, stable image formation can be performed.

[0191]

As described above, according to the present invention,
When the same print medium belongs to both of a transport drive system for transporting the image forming system and a transport drive system for transporting from the print medium storage device to the transport unit driven by the transport drive device Provided is an image forming apparatus capable of performing stable image formation on a print medium by matching the speeds of both systems, eliminating pushing and pulling of the print medium, and not affecting the image forming system by the influence of speed change. be able to.

[Brief description of drawings]

FIG. 1 is a diagram of an image forming apparatus according to a first embodiment.

FIG. 2 is a schematic diagram showing a feeding system and a print medium carrying system in the first embodiment.

FIG. 3 is a block diagram showing a control system of a conveyance drive motor of an image forming system and a drive motor of a feeding system in the first embodiment.

FIG. 4 is a diagram showing a motor drive PWM and a motor rotation speed signal in the first embodiment.

FIG. 5 is a schematic diagram showing a feeding system and a print medium carrying system in a second embodiment.

FIG. 6 is a block diagram showing a control system of a conveyance drive motor of an image forming system and a drive motor of a feeding system in the second embodiment.

FIG. 7 is a diagram showing a motor drive phase excitation signal and a motor rotation speed signal in the second embodiment.

FIG. 8 is a block diagram showing a control system of a conveyance drive motor of an image forming system and a drive motor of a feeding system in a third embodiment.

FIG. 9 is a diagram showing a third motor rotation signal and a speed fluctuation detection signal.

FIG. 10 is a motor speed control chart of the third embodiment.

[Explanation of symbols]

1 Scanner unit 2 rotating polygon mirror 3 cartridges 4 photoconductor 5 Development sleeve 6 Y developing cartridge 7M developing cartridge 8 C developing cartridge 9 BK developing cartridge 10 Transfer roller 11 Conveyor belt 11a drive roller 12 Paper feed unit 12a feeding roller 13 print media 14 Fixing device 15 Fixing roller 16 heater roller 17 Motor (DC motor) 18 CPU 19 Motor controller 20 Motor driver (for DC motor) 21 Motor driver (for DC motor) 22 Motor (DC motor) 24 MR sensor 25 waveform converter 26 code wheels 27 Photointerrupter 28 signal selector 29 counter 30 memory 31 counter table 32 Paper type detection unit 33 Motor driver (for stepping motor) 34 Motor driver (for stepping motor) 35 motor (stepping motor) 36 motor (stepping motor) 37 memory

Claims (11)

[Claims] 1. A transport driving device for transporting an image forming system at a predetermined process speed while restraining a print medium,
An image forming apparatus provided upstream of the image forming system and configured to feed a print medium from a print medium storage device to a transport unit driven by the transport drive device, the transport drive device comprising: The feeding drive device is provided with the same type of drive means, and the detection means for detecting the drive speed of the drive means of at least one of the drive devices, and the speed control of both drive means by the speed detected by the detection means An image forming apparatus, comprising: a speed control unit that performs driving, wherein the speed control unit generates a drive signal and transmits the drive signal to both drive units to drive both drive units. 2. The image forming apparatus according to claim 1, wherein the detection means for detecting the drive speed of the drive means is provided in the drive means for driving at least one of the drive devices. 3. The image forming apparatus according to claim 1, wherein the detection means for detecting the drive speed of the drive means is provided in at least one of the transport drive device and the feeding drive device. 4. The image forming apparatus according to claim 1, wherein the drive means of the same type of the conveyance drive device and the feeding drive device is a stepping motor. 5. The image forming apparatus according to claim 1, wherein the drive means of the same type of the conveyance drive device and the feeding drive device is a DC brushless motor. 6. The image forming apparatus according to claim 1, wherein the speed control means uses a high-speed product-sum calculation element. 7. The image forming apparatus according to claim 1, wherein a digital signal processor is used as the speed control means. 8. The detection means for detecting the drive speed of the DC brushless motor detects the pattern magnetized on the rotor of the DC brushless motor with a ferromagnetic magnetic effect type sensor to detect the drive speed of the DC brushless motor. The image forming apparatus according to claim 5, wherein the image is detected. 9. The detecting means for detecting the drive speed of the drive means detects the drive speed of the drive means by the output of an encoder mounted in the vicinity of the drive means. 5. The image forming apparatus according to item 5. 10. The speed control means has an error detection means for comparing an output cycle of the drive speed detection means in a predetermined section with a reference cycle and detecting an error therebetween.
The image forming apparatus according to claim 1, wherein the speed of the driving unit is controlled based on the output of the error detecting unit. 11. The image forming apparatus according to claim 1, further comprising a storage unit, wherein the speed control unit generates a type of print medium before printing at the time of printing and speed fluctuation. An image forming apparatus characterized in that the timing and the amount of speed fluctuation are respectively stored in the storage means, and the speed control of the drive means is corrected based on the stored data.