JPH11194695A - Device and method for image forming - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make respective driving means possible to start up, without enlarg ing a power source. SOLUTION: This device is allowed to adopt a stepping motor for driving means 15. At the start up of the driving means 15, in other wards, at the start up of an original platen 3 when the large torque is required, the current I (1-1) is supplied, the specified time T1 later, and when the original platen 3 becomes to be rotated at uniform speed, the current supplied to the original platen 3 is lowered. A period of time T2 later, when a paper feeding roller 6 becomes so as to be driven at the uniform speed, the current I (1-3) is supplied to the driving means 15, simultaneously the current I (2-1) is supplied to the driving means 16, and the fixing roller 13 is allowed to start. The period of time T3 later, when the driving means 16 is driven, the fixing roller 13 is driven at the uniform speed, a signal is sent so as to supply the current I (2-3) to the driving means 16, and the current I (2-3) is supplied to the driving means 16.

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 and an image forming method. More specifically,
The present invention relates to an image forming apparatus and an image forming method in which a current supplied to a first driving unit for driving an image forming mechanism and a current supplied to a second driving unit for driving a paper feed system are appropriately controlled. It is about.

[0002]

2. Description of the Related Art In a conventional image forming apparatus of this type, a stepping motor is used as a driving means. When a signal indicating the start of a copying operation is input, the image forming mechanism is driven. Both the driving means and the driving means for driving the sheet feeding and conveying system are simultaneously driven.

In order to activate the first drive unit for driving the image forming mechanism and the second drive system unit for driving the paper feed / conveyance system, the activation required for each drive unit is required. In order to obtain torque, a high-level current value is supplied to the stepping motor, which is a driving unit, for a certain time at the time of startup, and a low-level current value is supplied after the stepping motor starts rotating at a constant speed. Had been supplied.

As described above, in the conventional image forming apparatus, the current is supplied to the first drive unit for driving the image forming mechanism and the second drive system unit for driving the paper feed system. Is divided into two steps.

[0005]

However, in the above-described conventional image forming apparatus, the driving means for driving the image forming mechanism and the driving means for driving the paper feed system are simultaneously activated, that is, In order to simultaneously obtain a large driving torque required at the time of starting, a power supply capacity for securing an output current value sufficient to simultaneously supply a high current to both of these driving means is required.

As described above, in the conventional image forming apparatus, it is necessary to increase the current capacity of a power supply for supplying a current to each driving means, and the power supply must be enlarged.

In view of the above, it is an object of the present invention to provide an image forming apparatus and an image forming method capable of appropriately starting each drive unit without increasing the power supply capacity. Is to do.

[0008]

In order to achieve the above object, an image forming apparatus according to the present invention comprises a first driving means for driving an image forming mechanism and a second driving means for driving a sheet feeding and conveying system. Current control for supplying a high-level current when activating each of the first and second driving units, and supplying a low-level current after a predetermined condition is achieved. Means, said first and second
And timing control means for controlling the timing so that the periods for supplying the high-level current to the driving means do not overlap. Here, a stepping motor can be provided as the first and second driving means. Further, after supplying a high level current to the first and second driving means, a low level current is supplied after the electric motor included in each driving means starts to rotate at a predetermined constant speed. It is preferred to do so. Further, the image forming apparatus is a copying apparatus that forms an image according to an electrophotographic method, and can supply a high-level current to be supplied to the first and second driving units in a time-division manner at the start of a copying operation. it can. When the copying apparatus has a document table, it is preferable to operate the current control means and the timing control means when the document table moves forward and backward, respectively.

An image forming method according to the present invention is directed to an image forming method for an image forming apparatus having a first driving unit for driving an image forming mechanism and a second driving unit for driving a sheet feeding and conveying system. In executing current control for supplying a high-level current when activating the first and second driving means and supplying a low-level current after a predetermined condition is achieved, the first and second driving means are controlled. It has a control step of controlling timing so that periods for supplying a high-level current to the driving means do not overlap. Here, a stepping motor can be provided as the first and second driving means. Further, after supplying a high level current to the first and second driving means, a low level current is supplied after the electric motor included in each driving means starts to rotate at a predetermined constant speed. It is preferred to do so. Further, the image forming method is a copying method for forming an image in accordance with an electrophotographic method, wherein a high-level current to be supplied to the first and second driving means at the start of a copying operation is supplied in a time sharing manner. It is possible. At this time, it is preferable to execute the control steps when the document table moves forward and backward.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus to which the present invention is applied will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a cross-sectional configuration of an image forming apparatus of a platen moving type according to the present embodiment. In FIG. 1, reference numeral 1 denotes a platen glass on which a document is placed; 2, a platen cover for opening and closing in a vertical direction to fix the document; 3, a platen including a platen glass 1 and a platen cover 2. Reference numeral 4 denotes a sheet cassette, and reference numeral 5 denotes a copy sheet (hereinafter, referred to as sheet P). A paper feed roller 6 feeds and transports the paper P one by one from the paper feed cassette 4. 7 is a photosensitive drum 1
A registration roller for matching the image destination of the electrostatic image formed on the top of the sheet P with the leading end of the transfer position of the sheet P, 8 is a document irradiation lamp for irradiating a document, and 9 is a home position provided on the document table 3. Flag 10, reference numeral 10 denotes a photosensitive drum for forming a reflected light image of a document irradiated by document lamp 8 as an electrostatic image, reference numeral 11 denotes a developing device for developing the electrostatic image using toner, and reference numeral 12 denotes a developing device for developing the electrostatic image. A transfer separation charger for transferring and separating the imaged toner onto the sheet P, a fixing roller 13 for heating and fixing the toner image transferred on the sheet P, and a fixing roller 14 for detecting that the document table 3 has reached the reading start position. This is a home position detecting means for detecting. Reference numeral 15 denotes a drive unit for driving the document table 3 and the paper feed roller 6, and 16 denotes a drive unit for driving the photoconductor such as the registration roller 7 and the photosensitive drum 10 and the fixing roller 13, and both use a stepping motor. Have been.

FIG. 2 shows control blocks associated with the driving means 15 and 16 in the image forming apparatus shown in FIG. In the figure, reference numeral 17 denotes a paper feed drive transmitting means for transmitting the drive of the drive means 15 to the paper feed roller 6, 18 a registration drive means for transmitting the drive of the drive means 16 to the registration roller 7, and 19 a photosensitive drum 10 or the like. A photoconductor drive transmission unit that transmits the drive of the driving unit 16 around the photoconductor, 20 is a motor driver that controls power (constant current control) supplied to the driving units 15 and 16, and 21 is a motor driver. It is a DC power supply that supplies power. Reference numeral 22 denotes an MPU that controls the image forming apparatus. The MPU 22 includes two driving systems including a paper feed roller 6 and a document table 3 driven by the driving unit 15, a registration roller 7 driven by the driving unit 16, and a photoconductor peripheral. Control is performed to divide the peak current for the three drive systems of the unit 40 and the fixing roller 13. Also, 23
An operation unit supplies a start signal for a copying operation to the MPU 22. The description of the numbers described in FIG. 1 is omitted.

FIGS. 3 and 4 are timing charts showing the operation of the present image forming apparatus. Here, FIG. 3 shows the timing for driving five driving systems (the paper feeding roller 6, the document table 3, the registration roller 7, the photosensitive member peripheral portion 40, and the fixing roller 13) relating to the image forming operation and the paper feeding and conveying system. FIG.
Indicates a current value supplied to the driving units 15 and 16 during the copying operation.

The hatched portions in FIG. 3 indicate the driving of five driving systems (the paper feeding roller 6, the document table 3, the registration roller 7, the photosensitive member peripheral portion 40, and the fixing roller 13) related to the image forming operation and the paper feeding and conveying system. Is performed during the period. The hatched portions in FIG. 4 indicate current values supplied to the driving units 15 and 16.

FIGS. 5 and 6 are flow charts showing the current division control realized by the present image forming apparatus.

Next, the operation of the image forming apparatus will be described in detail with reference to FIGS.

First, when it is detected that a signal for starting an image forming operation from the operation unit 23 is input to the MPU 22 (step S500), the image forming apparatus shifts from the standby mode to the copy mode, and The table 3 is driven by the driving unit 15, moves backward in the direction of arrow b in FIG. 1, and is supplied with the current I (1-1) when the document table is started (step S501).

The paper feed roller 6 is arranged such that the original table 3
1 only, the sheet P is rotated in the direction of the arrow a in FIG. 1 to push the sheet P to the registration roller 7, and then an appropriate amount of loop is formed to terminate the transmission of the drive to the sheet feeding roller 6. I do. The image forming apparatus has a configuration in which the sheet feeding operation ends when the document table 3 reaches the home position. The driving unit 15 is driven in the opposite rotation direction when the original platen 3 is moved in the direction of arrow b and when it is moved in the direction of arrow c.

A stepping motor is used as the driving means 15.
When a large torque is required when the driving unit 15 is started, that is, when the document table 3 is started, the current I (1-1) is supplied,
When the rotation of the platen 3 starts to rotate at a constant speed after the predetermined time T1 has elapsed (step S502), the current supplied to the platen 3 can be reduced, and thus the driving unit 15 is driven.
, And at this time, a signal is sent from the MPU 22 to turn on the paper feed roller drive transmission means 17 for transmitting the drive of the drive means 15 to the paper feed roller 6.
The paper feed roller 6 is activated (step S503).

Therefore, the current I (1-2) is the sum of a low current value supplied after the platen 3 starts to move at a constant speed and a high current value supplied when the paper feed roller is started. It has become.

A known electromagnetic clutch is used for the paper feed roller drive transmission means 17.

The driving means 16 drives the paper transport path from the registration roller 7 through the photosensitive drum 10 and the fixing roller 13 until the paper is discharged from the main body, and drives the photosensitive member peripheral portion 40. A known electromagnetic clutch is used as the registration drive transmission unit 18 that transmits the drive of the drive unit 16 to the registration roller 7.

When the period T2 has elapsed since the feed roller 6 was driven and the feed roller 6 starts to move at a constant speed (step S504), the driving means 15 supplies the current I (1-
At the same time as 3) is supplied, a signal for driving the driving means 16 is output from the MPU, and the current I
(2-1) is supplied, and the driving of the fixing roller 13 is started (step S505).

When the period T3 has elapsed since the driving of the driving unit 16 and the fixing roller 13 starts rotating at a constant speed (step S506), the current I (2) is supplied from the MPU 22 to the driving unit 16 via the motor driver 20. -3) to supply a current I (2
-3) is supplied. At this time, a signal for turning on the photoconductor drive transmission unit 19 is transmitted from the MPU 22, and the driving of the photoconductor peripheral portion 40 is started (step S507).

When a period T4 elapses from the start of driving of the photosensitive member peripheral portion 40 and the photosensitive member peripheral portion 40 starts to move at a constant speed, the current I (2-3) is supplied to the driving means 16. Is performed (step S509).

The registration roller 7 includes an optical system including the document table 3 and a document irradiation lamp 8, a well-known high-voltage controller, a developing unit 11, a photosensitive drum 10, and the like.
The timing for aligning the leading edge of the toner image of the document image obtained above with the leading edge of the sheet P is set.
Further, as described above, the registration roller 7 uses the drive transmission unit 17 for transmitting the drive of the drive unit 16.

The home position detecting means 14 (hereinafter, referred to as HP detecting means) for detecting that the document table 3 is at the reading start position until the document table 3 is returned and detected at that position. Drive transmission means 15
The paper feed roller 6, which is rotationally driven in the direction of the arrow a in FIG. 1, hits the paper P to the registration roller 7, forms an appropriate amount of loop, and ends the paper feed operation.
In the present image forming apparatus, the timing at which the sheet feeding operation ends at the same time as the detection of the home position is set.

When it is detected that the platen 3 has moved in the reverse direction and the HP flag 9 provided on the platen 3 has reached the home position (step S510), the driving means 15
The current supply to the sheet feeder is stopped, the document table 3 stops at the home position, and the MPU 22 feeds the sheet feed roller drive transmission means OF.
The F signal is transmitted, and the driving of the paper feed roller 6 stops (step S600).

When the period T5 has elapsed since the document table 3 was stopped at the home position (step S601), the MPU
An instruction to supply the current I (1-4) to the drive unit 15 is transmitted from the motor 22 to the motor driver 20 and the document table 3
Is driven in the forward direction (step S602).

A period T6 elapses from the timing when the platen 3 starts to be driven in the forward direction (step S603).
When the forward movement of the document table 3 starts to rotate at a constant speed, the drive from the driving unit 16 is transmitted to the registration roller 7 via the registration drive transmission unit 18, and the registration roller 7 is driven (step S604).

At this time, the driving means 15 is supplied with the current I (1-5) in the constant speed rotation mode, and the driving means 16 is supplied with the current I (2-4). After the period of time T7 elapses after the driving of the registration roller 7, when the rotation at a constant speed starts (step S605), the current I (2-5) is supplied to the driving means 16 (step S606).

In the present image forming apparatus, the document table 3 is driven from the home position in the direction of arrow c in FIG. 1 so as to attain a predetermined reading speed.
When the registration roller 7 is driven via the registration drive transmission unit 18 after the time period T6 has elapsed from the timing of transmitting the drive of the drive 5, the leading end of the toner image on the photosensitive drum 10 is aligned with the leading end of the paper P. It is composed.

After the above control, the toner image is transferred to the paper P by the transfer charger 12, and the toner image transferred onto the paper P is thermally fixed by the fixing unit including the fixing roller 13, and the paper is discharged from the apparatus main body. I do. When the image forming operation is completed (step S607), the MPU 22 drives the driving units 15 and 16
Control to stop the current supply to the power supply (step S6)
08).

(Embodiment 2) In Embodiment 1 described above, an image forming apparatus using a platen moving system has been described as an example. However, the present invention can be applied to an image forming apparatus using an optical system moving system. Of course.

(Embodiment 3) In Embodiment 1 described above, two driving means are used: one for driving a document table and a paper feed roller, and one for driving a fixing roller, a photosensitive drum, and a registration roller. Although the configuration is used, the copying paper reaches the registration rollers to form a loop before the image forming operation is performed, and the paper feeding operation is completed. As long as the periods for supplying the levels do not overlap, the number of driving means need not be two.

Further, the order of driving the driving systems related to the image forming operation and the sheet feeding / conveying system may be changed.

(Effects of Embodiment) As described above, according to the embodiment of the present invention, in performing the image forming operation in response to the instruction from the operation unit, the image forming operation and the sheet feeding and conveying system At the time of activation of the drive system related to, the peak current value is suppressed by controlling so that periods during which a high value current is supplied until the drive system related to the image forming operation and the sheet feeding conveyance system performs constant-speed rotation do not overlap, The current capacity of the power supply that supplies the current to the stepping motor, which is the driving means, can be reduced. Therefore, it is possible to provide an image forming apparatus with a reduced power supply.

[0038]

As described above, according to the present invention, each drive means can be appropriately started without increasing the power supply capacity.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an image forming apparatus to which the present invention is applied.

FIG. 2 is a diagram showing an electrical control block of the image forming apparatus shown in FIG.

FIG. 3 is a timing chart illustrating an operation of the image forming apparatus.

FIG. 4 is a timing chart illustrating an operation of the image forming apparatus.

FIG. 5 is a flowchart illustrating a control procedure of the image forming apparatus.

FIG. 6 is a flowchart illustrating a control procedure of the image forming apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 platen glass 2 platen cover 3 platen 4 paper cassette 5 paper P 6 paper feed roller 7 registration roller 8 document irradiation lamp 9 home position (HP) flag 10 photosensitive drum 11 developing device 12 transfer separation charger 13 fixing roller 14 Home position (HP) detection means 15 Driving means 16 Driving means 17 Paper feed roller drive transmission means 18 Registration drive transmission means 19 Photoconductor drive transmission means 20 Motor driver 21 DC power supply 22 MPU 23 Operation unit

Claims (10)

[Claims] 1. An image forming apparatus comprising: a first driving unit for driving an image forming mechanism; and a second driving unit for driving a sheet feeding / conveying system, wherein each of the first and second driving units is A current control unit for supplying a high-level current when starting up and supplying a low-level current after a predetermined condition is achieved; and a period for supplying a high-level current to the first and second driving units. An image forming apparatus comprising: timing control means for controlling timing so as not to overlap. 2. The image forming apparatus according to claim 1, further comprising a stepping motor as the first and second driving units. 3. The motor according to claim 1, wherein after supplying a high-level current to the first and second driving means, the electric motor included in each of the driving means rotates at a predetermined constant speed. An image forming apparatus for supplying a low-level current after the image formation. 4. The image forming apparatus according to claim 1, wherein the image forming apparatus is a copying apparatus that forms an image according to an electrophotographic method, and a high level current supplied to the first and second driving units at the start of a copying operation. An image forming apparatus which supplies the image data in a time-division manner. 5. An image according to claim 4, wherein said copying apparatus has a document table, and operates said current control means and said timing control means when said document table moves forward and backward, respectively. Forming equipment. 6. An image forming method for an image forming apparatus, comprising: a first driving unit for driving an image forming mechanism; and a second driving unit for driving a sheet feeding / conveying system, wherein the first and second driving units are provided. In executing the current control for supplying a high-level current when starting the respective means and supplying a low-level current after a predetermined condition is achieved, a high-level current is supplied to the first and second driving means. An image forming method, comprising: a control step of controlling timing so that periods for supplying image data do not overlap. 7. The image forming method according to claim 6, further comprising a stepping motor as the first and second driving units. 8. The motor according to claim 6, wherein after supplying a high-level current to said first and second driving means, the electric motors included in each of said driving means rotate at a predetermined constant speed. An image forming method comprising supplying a low-level current after the image formation. 9. The image forming method according to claim 6, wherein the image forming method is a copying method for forming an image according to an electrophotographic method, wherein a high-level current supplied to the first and second driving units at the start of a copying operation. Is supplied in a time-sharing manner. 10. The image forming method according to claim 9, wherein the control step is executed when the platen moves forward and backward.