JPH08220966A - Drive control device for image forming device - Google Patents

Abstract

PURPOSE: To prevent generation of density unevenness of an output image, and occurrence of the image forming operation disabled state, by constituting the control parameter of a control means possible of resetting corresponding to the transfer function of a drive transmission system. CONSTITUTION: A feed back parameter calculating part 20 of a drive control device 16 calculates the feed back control parameter C (s) by inputting the transfer function G (s) outputted from the transfer function identifying part 18 and the target transfer function Go (s) outputted from the target transfer function storing part 19, and the feed back parameter setting part 21 resets the parameter C (s) to the memory, etc., as the new feed back control parameter C (s). When the setting feed back control parameter C (s) is renewed in this way, the control part 22 controls the drive circuit 15 based on the renewed feed back control parameter C (s) thereafter, and makes the transfer function of the drive transmission system consisting of a motor 2, a reduction gear 3 and a photoreceptor drum 4 approximately equal to the target transfer function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for an electrophotographic image forming apparatus for forming an image on a rotating member by laser scanning, and more particularly to at least one of torque generating means, torque transmitting means and rotating member. The present invention relates to a drive control device for an image forming apparatus, which suppresses fluctuations in the rotation speed of a rotating member even when the above is replaced to prevent density unevenness in an output image and disable the image forming operation.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic laser printer or an electronic copying machine, a scanning device is used as a rotating member such as a photosensitive drum, a transfer drum, or an intermediate transfer belt that rotates in a sub-scanning direction. The laser light is scanned in the main scanning direction to form an image. Therefore, it is an important subject to suppress the rotation speed of the rotating member to prevent density unevenness occurring in the sub-scanning direction on the formed image.

Therefore, as a conventional image forming apparatus that suppresses such a variation in the rotation speed of the rotating member, for example,
JP-A-63-177190 and JP-A-5-53
Some are disclosed in Japanese Patent No. 382. In these image forming apparatuses, a flywheel having a large moment of inertia is attached to the shaft of a rotary member, and fluctuations in the speed of the rotary member are suppressed by the inertia of the flywheel.

Further, as another drive control method for suppressing the speed fluctuation of the rotating member, for example, Japanese Patent Laid-Open No. 5-188484.
Some are disclosed in Japanese Patent Publication. In this drive control method, in the speed control of the image reading means of the copying machine, prescan is performed when the power is turned on, the torque constant and the armature resistance are measured at that time, and the speed feedback gain for the next time and thereafter is determined from this value. However, by performing a normal scan based on this, fluctuations in the position and speed of the image reading unit are suppressed.

[0005]

However, according to the conventional image forming apparatus, in the former case, the rotation member is driven based on the control parameter (flywheel inertia) set according to the transfer function of the drive transmission system. Therefore, if any of the rotating member, torque transmitting means, and motor is replaced due to damage or deterioration, the dynamic characteristics of the drive transmission system will change from the dotted line to the solid line as shown in FIG. If the rotary member is drive-controlled using the control parameters before component replacement as it is, the transfer function of the drive transmission system does not match the target transfer function shown in FIG. 10 (b). That is, before the parts are replaced, the transfer function of the drive transfer system is the target transfer function or a transfer function close to the target transfer function. As shown in FIG. 10 (b), the transfer function of the drive transfer system is the speed of the rotating member. The highest responsive frequency (resonance frequency) f ₀ and the vibration frequency (torque generating means and the frequency of torque fluctuation occurring for each rotation of the torque transmitting means, the gear forming the torque transmitting means, or the drive) The frequency of torque fluctuation that occurs for each tooth of the belt and the frequency of torque fluctuation that occurs at each magnetic pole switching timing in the torque generating means) f _{1 to} f ₆ do not overlap. However, when parts are replaced and the transfer function of the drive transmission system changes as shown in (a) of FIG. 10, the resonance frequency) f ₀ and the vibration frequencies f _{1 to} f ₆ overlap each other, and the speed fluctuation of the rotating member changes. The problem is that the density of the output image increases and the density unevenness (color unevenness in the case of full color) occurs in the output image, or the drive transmission system of the rotating member becomes unstable and the rotating member stops and the image forming operation becomes impossible. Occurs.

Further, in the case of the latter speed control method, since the control is performed based on the torque constant of the torque generating means and the armature resistance, it is not possible to cope with the change of the transfer function after the parts are replaced. As a result, the problems described above occur.

An object of the present invention is to suppress the increase of the rotational speed fluctuation of the rotating member even if at least one of the torque generating means, the torque transmitting means, and the rotating member is replaced, so that the density unevenness of the output image is generated, An object of the present invention is to provide a drive control device of an image forming apparatus capable of preventing the image forming operation from being disabled.

[0008]

In view of the above problems, the present invention suppresses an increase in the rotational speed fluctuation of the rotating member even if at least one of the torque generating means, the torque transmitting means, and the rotating member is replaced. In order to prevent the occurrence of density unevenness of the output image and the disabling of the image forming operation, control parameter setting means for setting control parameters according to the transfer function of the drive transmission system, torque generating means, torque transmitting means, A control parameter calculating means for calculating and supplying a control parameter to the control parameter setting means for resetting when at least one of the rotating members is replaced, and a control means for controlling the drive means based on the control parameter are provided. A drive control device for an image forming apparatus is provided.

In the above structure, the control parameter calculating means measures the frequency characteristic of the transfer function of the drive transmission system based on the speed detecting section for detecting the rotational speed of the rotating member and the speed signal output from the speed detecting section. A frequency characteristic measuring unit, a transfer function identifying unit that identifies a transfer function based on the frequency characteristic, a target transfer function storage unit that stores a target transfer function of a drive transfer system, and a transfer function output from the transfer function identifying unit. It is preferable that the control parameter calculation unit includes a control parameter calculation unit that calculates a control parameter by performing a comparison calculation on target transfer functions output from the target transfer function storage unit.

In the control parameter calculation unit, the transfer function output from the transfer function identification unit is

[Equation 4] And the target transfer function output from the target transfer function storage is

(Equation 5) in the case of,

(Equation 6) It is preferable to have a configuration for performing the above calculation.

[0011]

When at least one of the torque generating means, the torque transmitting means, and the rotating member of the drive transmission system is replaced, the newly calculated control parameter is reset in the control parameter setting means. When the control parameter is reset, the drive means is controlled based on the reset control parameter thereafter, the transfer function of the drive transmission system is made to match the target transfer function, and the response is the most at the frequency of the speed fluctuation of the rotating member. Prevents overlapping of high frequency (resonance frequency) and vibration frequency.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A drive controller for an image forming apparatus according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the configuration of an image forming apparatus to which the present invention is applied. The image forming apparatus 1 includes a motor 2 that generates a rotation torque, a reduction gear 3 that receives the rotation torque from the motor 2 and transmits the rotation torque to the photosensitive drum 4.
It rotates based on the rotation torque input from the reduction gear 3,
It has a photosensitive drum 4 that forms an electrostatic latent image on the surface by being exposed by an optical scanning device (not shown), and a flywheel 5 that suppresses rotational fluctuation of the photosensitive drum 4.

The image forming apparatus 1 further includes conveying devices 9 and 10 for conveying recording paper, a developing device 11 for developing the electrostatic latent image on the photosensitive drum 4 with toner, and recording transferred from the photosensitive drum 4. A fixing device 12 for fixing the transferred image on the paper is provided. As a driving mechanism for these, a motor 6 for generating a rotational torque, and a rotational torque from the motor 6 are input to convey the conveying devices 9, 10, the developing device 11, and the developing device 11. A drive belt 7 wound around each timing pulley (not shown) of the fixing device 12, a transmission gear 8 for transmitting to the conveying device 9, and a belt tensioner 13 for making the drive belt 7 have a predetermined tension are provided. . A gear (not shown) is provided between the transport device 9, 10, the developing device 11, and the fixing device 12 and the drive belt 7 to adjust the rotation speed according to the number of rotations required by each device. There is.

It is desirable that the motors 2 and 6 be driven at low cost and with high accuracy. For example, a DC brushless motor having a shaft with a gear cutting process or a stepping motor is used. When a stepping motor is used, in order to reduce fluctuations in rotation speed and power consumption, constant current driving is performed with a current value that is as small as possible while considering load torque.

As the reduction gear 3, the transmission gear 8 or a gear for adjusting the rotation speed according to the number of rotations required by each device, for example, polyacetal (POM) having good tooth contact and hardly transmitting torque fluctuation is used. Use a configured helical gear.

As the drive belt 7, a timing belt having a pitch as small as possible is used in consideration of load torque in order to increase the rotational fluctuation frequency generated by tooth contact and ensure high precision drive. Further, when the load torque is small, if a steel belt is used instead of the timing belt, the rotation fluctuation due to tooth contact is eliminated, so that more accurate driving can be realized.

Each of the conveying devices 9, 10, the developing device 11, and the fixing device 12 is provided with a torque cutting device (not shown) for cutting the rotational torque according to the drive timing from the sequencer. For this torque cutting device,
Use an electromagnetic clutch or powder clutch.

As shown in FIG. 2, the belt tensioner 13 includes a main body 13A, a rod portion 13C having a roller 13B at the tip thereof which rotates in contact with the drive belt 7, and a rod portion 13C slidable in the arrow direction. Sliding part 13D supported on
And an elastic member 13E attached between the rear end of the rod portion 13C and the main body 13A, and a predetermined tension is constantly applied to the drive belt 7 by elastic deformation of the elastic member 13E. .

FIG. 3 shows an embodiment of the drive control device applied to the image forming apparatus. The drive control device of this image forming apparatus includes a speed detection unit 14 that detects the rotation speed of the photosensitive drum 4, a drive circuit 15 that drives the motor 2, and a drive circuit 15 that is normally based on a feedback parameter that is set. When at least one component of the motor 2, the reduction gear 3, or the photoconductor drum 4 is replaced, the transfer function of the drive transmission system is set to the target transfer function based on the speed signal output from the speed detection unit 14. Drive controller 16 for resetting the foot-back parameter for

The speed detector 14 includes a rotary encoder,
Alternatively, it is composed of a laser Doppler velocimeter.

The drive unit 15 outputs a drive signal corresponding to the slack control signal output from the drive control unit 16 to drive the motor 2. For example, when the motor 2 is a stepping motor, a pulse signal having a predetermined command frequency is output, and when the motor 2 is a DC motor, an exciting current having a predetermined value is supplied.

The drive control device 16 measures the frequency characteristic of the transfer function of the drive transmission system based on the speed signal output from the speed detecting section 14, that is, the frequency characteristic for measuring the frequency characteristic of the relationship between the frequency of the speed fluctuation and the response. A characteristic measuring unit 17, a transfer function identifying unit 18 for identifying the transfer function G (s) based on the frequency characteristic calculated by the frequency characteristic measuring unit 17, and a target transfer function G ₀ (s) of the drive transmission system are stored. The target transfer function storage unit 19, the transfer function G (s) output from the transfer function identifying unit 18, and the target transfer function G ₀ (s) output from the target transfer function storage unit 19 are compared and calculated to perform feedback control. The feedback parameter calculation unit 20 for calculating the parameter C (s) and the feedback parameter calculation unit 20
Feedback control parameter C calculated in
(s) is set in a memory or the like, a feedback parameter setting unit 21, a control unit 22 that controls the drive circuit 15 based on the set feedback control parameter C (s), a normal mode and a feedback parameter reset after component replacement. It is configured to include a mode switching unit 23 that switches the parameter changing mode for setting. These are configured by combining a microprocessor or a digital signal processor and a storage element, and data transfer between each device is performed by parallel data transfer in order to shorten processing time.

The feedback parameter calculation section 20
The transfer function output from the transfer function identification unit 18 is

(Equation 7) Then, the transfer function output from the target transfer function storage unit 19 is

(Equation 8) in the case of,

[Equation 9] Is calculated.

The mode switching section 23, as shown in FIG.
The image forming apparatus 1 is composed of a manual mechanical switch 23 capable of opening and scanning the front panel 24. Alternatively, the operation panel 25 provided near the platen may be arranged as a soft switch or a mechanical switch. Further, as shown in FIG. 5, it may be configured by a computer 27 capable of remote control. In that case, if each unit of the drive control device 16 described above is provided on the computer 27 side, versatility and cost are advantageous. Becomes

The operation of the drive control device for the image forming apparatus of the present invention will be described below. First, when the operator turns on the power switch and inputs a copy start command, in the drive control device 16, the control unit 22 causes the drive circuit 15 to perform a predetermined control based on the feedback control parameter set in the feedback parameter setting unit 21. A signal is output, and the drive circuit 15 drives the motor 2 with a drive signal (a pulse signal having a predetermined command frequency when the motor 2 is a stepping motor) according to the control signal output from the control unit 22. When the motor 2 is driven, its rotational torque is transmitted to the photoconductor drum 4 via the reduction gear 3 to rotate the photoconductor drum 4 at a predetermined speed.

On the other hand, the motor 6 is driven at the same time, and its rotational torque is transmitted to the drive belt 7 and the conveying device 9 via the transmission gear 8. The drive belt 7 is rotated when a rotation torque is input, and is rotated from each timing pulley to the developing device 1.
1. Rotation torque is input to the fixing device 12, the fixing device 12, and the conveying device 10.

Next, when the photosensitive drum 4 is exposed by the optical scanning device based on the reading of the original image, the electromagnetic clutch of the developing device 11 is turned on at a predetermined timing, and the developing device 11 receives the input rotational torque. By supplying toner to the photosensitive drum 4, the electrostatic latent image on the photosensitive drum 4 is developed with toner. Further, the electromagnetic clutches of the transfer devices 9, 10 are turned on at a predetermined timing, and the transfer devices 9, 10
Shows the recording paper on the photosensitive drum 4 according to the input rotation torque.
Supply to the transcription point.

When the transfer onto the recording paper is performed in this manner, the recording paper is supplied to the fixing device 12 by the conveying devices 9 and 10. At this time, the electromagnetic clutch of the fixing device 12 is turned on, and the fixing device 12 fixes the transferred image on the recording paper by the input rotation torque, and the copy operation is completed.

On the other hand, when any one of the motor 2, the reduction gear 3, and the photosensitive drum 4 is damaged or aged and at least one of them is replaced, the mode switching unit 2
Input the parameter change command from 3. The control unit 22 that has received the command signal outputs a predetermined control signal to the drive circuit 15 based on the past feedback control parameters, drives the motor 2 and rotates the photosensitive drum 4.

When the photosensitive drum 4 rotates, a speed signal is output from the speed detecting section 14 to the frequency characteristic measuring section 17,
The frequency characteristic measuring unit 17 measures the frequency characteristic of the transfer function of the drive transmission system based on the speed signal. The measured value is output to the transfer function identifying unit 18, the transfer function identifying unit 18 identifies the transfer function G (s), and outputs it to the feedback parameter calculating unit 20.

The feedback parameter calculation unit 20
The transfer function G (s) output from the transfer function identification unit 18 and the target transfer function G output from the target transfer function storage unit 19
_The feedback control parameter C (s) is calculated by inputting ₀ (s) and performing the above calculation, and this is given to the feedback parameter setting unit 21. The feedback parameter setting unit 21 resets this in the memory or the like as a new feedback control parameter C (s).

In this way, the setting feedback control parameter C of the feedback parameter setting section 21 is set.
When (s) is updated, the control unit 22 thereafter controls the drive circuit 15 based on the updated feedback control parameter C (s) to drive the motor 2, the reduction gear 3, and the photosensitive drum 4. The transfer function of the transfer system is made substantially equal to the target transfer function so as to prevent the frequency (resonance frequency) having the highest responsiveness at the frequency of the speed fluctuation of the photosensitive drum 4 from overlapping with the excitation frequency.

FIG. 6 shows a feedback control loop in which the reference frequency output from the reference frequency generator 26 and the measurement frequency corresponding to the speed of the photosensitive drum 4 output from the speed detector 14 are input to the subtractor 61. Then, the subtraction process is performed, and the feedback signal Δu is calculated according to the difference. The feedback signal Δu is added to the reference frequency from the reference frequency generator 26 in the adder 62, and the added value is output to the drive circuit 15. Here, the reference frequency generator 2
6 can be composed of a crystal oscillator or a ceramic oscillator.

In the embodiment described above, the photosensitive drum is 1
Although two image forming apparatuses have been described, the present invention can be applied to a color image forming apparatus having a plurality of photosensitive drums.

FIG. 7 shows another embodiment of the image forming apparatus using the drive control apparatus of the present invention. The image forming apparatus of this embodiment receives a rotational torque from a motor 28 and is driven to supply a recording paper in a direction of an arrow.
A recording paper conveyance belt 31 for driving the recording paper by receiving rotational torque from the motor 30, a suction device 32 for adsorbing the recording paper on the recording paper conveyance belt 31, and a motor 33.
(33A to 33D) to the reduction gear 34 (34A to 34D)
D) driven by the photoconductor drum 35 (35A to 3A)
5D), an optical scanning device 36 (36A to 36D) for exposing the photosensitive drum 35 to form an electrostatic latent image on the surface, and Y, M, C for developing the electrostatic latent image on the photosensitive drum 35 with toner. ,
A color toner image formed on each photoconductor drum 35 is transferred onto a recording paper conveyed through a Bk (yellow, magenta, cyan, black) developing device 37 (37A to 37D) and the recording paper conveyance belt 31. Transfer roll 38 (38A
To 38D), a charger 39 (39A to 39D) for charging the photosensitive drum 35 before the formation of the electrostatic latent image, and a fixing roll 40 for fixing the transferred image on the recording paper after the transfer is completed. Has been done.

In such an image forming apparatus, Y,
At least one of the transmission systems of the motor 33, the reduction gear 34, and the photoconductor drum 35 in each of the M, C, and Bk units.
Even if two parts are exchanged, if the transfer function of the transfer system is controlled by the drive control device so as to be always the target transfer function, the rotational fluctuation of the photosensitive drum 35 of each unit can be suppressed, As a result, it is possible to prevent color unevenness and color registration deviation in the recorded image on the recording paper.

Further, as shown in FIG. 8, by using the intermediate transfer belt 41 driven by a motor 42 in a color image forming apparatus, it is supplied to a secondary transfer point by a supply roll 44 rotated by a motor 43. It is also possible to prevent color unevenness of the color toner image and deviation of color registration when the color toner image is transferred onto the recording paper by the secondary transfer roll 45.

In the above embodiment, the gear for transmitting the driving torque from the motor to each load and the driving belt (timing belt, steel belt, etc.) can be substituted for each other.

[0040]

As described above, according to the drive control device of the image forming apparatus of the present invention, the control parameter of the control means can be reset according to the transfer function of the drive transmission system. Even if at least one of the transmission unit and the rotating member is replaced, it is possible to suppress an increase in the rotational speed fluctuation of the rotating member and prevent the occurrence of density unevenness in the output image and the inability to perform the image forming operation. .

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of an image forming apparatus to which the present invention is applied.

FIG. 2 is an explanatory diagram showing a configuration of a belt tensioner according to an embodiment.

FIG. 3 is an explanatory diagram showing an embodiment of a drive control device of the present invention.

FIG. 4 is an explanatory diagram showing a configuration of a mode switching unit according to an embodiment.

FIG. 5 is an explanatory diagram showing another configuration of the mode switching unit according to the embodiment.

FIG. 6 is an explanatory diagram showing a feedback control loop according to an embodiment.

FIG. 7 is an explanatory diagram showing a second embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a third embodiment of the present invention.

FIG. 9 is a graph showing changes in the transfer function of the drive transmission system before and after component replacement.

FIG. 10 is a graph showing the relationship between the excitation frequency in the target transfer function and the changed transfer function.

[Explanation of symbols]

 1 Image Forming Device 2 Motor 3 Reduction Gear 4 Photoreceptor Drum 5 Flywheel 6 Motor 7 Drive Belt 8 Transmission Gear 9, 10 Conveying Device 11 Developing Device 12 Fixing Device 13 Belt Tensioner 14 Speed Detecting Unit 15 Drive Circuit 16 Drive Control Device 17 Frequency characteristic measurement unit 18 Transfer function identification unit 19 Target transfer function storage unit 20 Feedback parameter calculation unit 21 Feedback parameter setting unit 22 Control unit 23 Mode switching unit 26 Reference frequency generation unit 28 Motor 29 Supply roll 30 Motor 31 Recording paper transport belt 32 Adsorber 33 (33A-33D) Motor 34 (34A-34D) Reduction gear 35 (35A-35D) Photosensitive drum 36 (36A-36D) Optical scanning device 37 (37A-37D) Developing machine 38 (38A-38D) Transfer Roll 3 (39A to 39D) charger 40 fixing roll 41 intermediate transfer belt 42 motor 43 motor 44 supply roll 45 the second transfer roller 46 fixing roll 61 subtractor 62 adder

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Claims (3)

[Claims] 1. An outer peripheral surface which is driven by a drive signal output from a drive means to generate a rotational torque, torque transmitting means for transmitting the rotational torque, and which is rotated by the transmitted rotational torque. In an image forming apparatus having a drive transmission system including a rotating member for forming an image on a surface, a control parameter setting unit that sets a control parameter according to a transfer function of the drive transmission system, the torque generation unit, and the torque transmission unit. A control parameter calculation means for calculating the control parameter when at least one of the rotating members is replaced and supplying the control parameter to the control parameter setting means for resetting; and controlling the drive means based on the control parameter. A drive control device for an image forming apparatus, comprising a control means. 2. The control parameter calculating means determines a frequency characteristic of a transfer function of the drive transmission system based on a speed detecting section for detecting a rotational speed of the rotating member and a speed signal output from the speed detecting section. A frequency characteristic measuring unit to measure, a transfer function identifying unit that identifies a transfer function based on the frequency characteristic, a target transfer function storage unit that stores a target transfer function of the drive transfer system, and an output from the transfer function identifying unit. 2. The drive control device for an image forming apparatus according to claim 1, further comprising: a control parameter calculation unit that calculates a control parameter by performing a comparison calculation of the transfer function to be performed and the target transfer function output from the target transfer function storage unit. 3. The transfer function output from the transfer function identification unit is calculated by the control parameter calculation unit as follows: Then, the target transfer function output from the target transfer function storage unit is If, then The drive control device for the image forming apparatus according to claim 2, wherein the drive control device has a configuration for performing the calculation.