JP3066106B2 - Image forming device - Google Patents

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 having a transfer medium such as a color copying machine.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus such as a color copier, it is necessary to transfer a plurality of toner images onto recording paper in a superimposed manner. Each toner image on the drum is superimposed and transferred onto the recording paper, or the toner image on the photosensitive drum is transferred and superimposed on the intermediate transfer medium a plurality of times, and is transferred onto the recording paper. Therefore, by increasing the speed of the transfer medium in the non-transfer area of the transfer medium such as the transfer drum or the intermediate transfer medium, the copy efficiency of the CPM or the like can be improved.

[0003]

However, in the above-described conventional image forming apparatus, when the speed of the transfer medium is increased in the non-transfer area, if the time required for the increase varies due to a load change or other reasons, the continuous increase occurs. When copying is performed, a jam may occur due to a clamping error, or irregularity of static elimination may occur, resulting in an abnormal image.

[0004] To explain this problem in detail, a servomotor is usually used as a motor for driving the transfer drum and the like, and its speed and position are controlled. That is, for example, when increasing the speed of the transfer drum in the non-transfer area, the speed is increased while controlling the speed toward the position by the speed increase command signal and the positional deviation. Become. In addition, since the motor rotates by exciting a plurality of phases, if a certain phase is not excited due to poor contact of a connector or the like, the torque of the motor decreases and the speed-up time becomes longer.

Therefore, in such a case, the speed increase is not completed until the recording paper is clamped, and the speed of the transfer drum is faster than the speed at which the transfer paper is fed into the clamper.
The transfer paper cannot be clamped, and a jam occurs. In addition, since the output of the static elimination charger and the speed of the transfer drum do not correspond to each other, uneven static elimination occurs. Further, when a certain phase of the motor is not excited, an overcurrent flows and the IC on the substrate may be destroyed. is there.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, an object of the present invention is to provide an image forming apparatus capable of preventing an abnormal image due to a jam or uneven charge removal.

[0007]

According to a first aspect of the present invention, there is provided an image forming apparatus for transferring a toner image onto a recording sheet using a transfer medium. Command means for generating a command for increasing the rotation speed of the transfer medium in the non-transfer area, and drive control means for controlling the drive means and increasing the rotation speed of the transfer medium according to a command from the command means Monitoring means for monitoring the rotational state of the transfer medium increased in speed by the drive control means, and a charge removing device for removing charge from the transfer medium after transfer
And the monitoring means detects the speed-up state of the transfer medium.
The transfer medium is the same when
Output of the static elimination charger so that static elimination is performed to one potential
And a static elimination output control means for controlling the operation .

[0008]

The second means is characterized in that, in the first means, when the monitoring means detects an abnormal rotation of the transfer medium, the rotation of the transfer medium is stopped and the abnormality is notified. The third means is the first or second means.
The transfer medium is a transfer drum around which recording paper is wound.

[0010]

[0011]

According to the first means, the transfer medium has the same potential regardless of whether the transfer medium has a charge elimination charger for removing the charge of the transfer medium after transfer, regardless of whether the speed of the transfer medium is increased or not. The charge is removed, and therefore, an abnormal image can be prevented.

In the second means, when the rotation abnormality of the transfer medium is detected, the rotation of the transfer medium is stopped and the abnormality is notified, so that the jam of the recording paper and the destruction of the IC can be prevented. In the third means, since the transfer medium is formed of a transfer drum around which a recording paper is wound, the transfer medium can be applied to color printing.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the image forming apparatus according to the present invention, FIG. 2 is a sectional view showing a color copying machine using the image forming apparatus of FIG. 1, and FIG. 3 is an operation of the color copying machine of FIG. FIG. 4 is a block diagram showing a detailed configuration of the control circuit of FIG. 1, and FIG. 5 is a main body CP of FIGS. 1 and 4.
FIG. 6 is a flowchart for explaining the main operation of the servo CPU of FIGS. 1 and 4, and FIG. 7 is a flowchart for explaining the detailed operation of the speed increase start control routine of FIG. 8 is a flowchart for explaining the detailed operation of the transfer drum speed-up state signal control routine of FIG. 6, and FIG. 9 is a flowchart for explaining the detailed operation of the transfer drum speed-up monitoring control routine of FIG. 10, FIG. 10 is a flowchart for explaining the detailed operation of the transfer static elimination ON control routine of FIG. 5, FIG. 11 is a flowchart for explaining the detailed operation of the transfer static elimination output switching routine of FIG. 5, and FIG. 6 is a flowchart illustrating a detailed operation of a transfer static elimination off control routine of FIG. 5;

In FIG. 1, a document image on a document table 1 is
Scanning is performed by the optical systems 2 to 7 (described later), an electrostatic latent image is formed on the photosensitive drum 8, and is developed with toner.
The recording paper (not shown) is conveyed by a registration roller 27 so as to coincide with the toner image on the photosensitive drum 8 and wound around the transfer drum 15. In the case of color copying, the recording paper rotates three times and is transferred onto the photosensitive drum 8 by the transfer charger 16. Are transferred in a superimposed manner. Next, when the transfer of the toner image is completed, the recording paper is separated from the separation charger 17 and the separation claw 2.
The transfer belt 29 is separated from the transfer drum 15 by the
And is transported in the direction of a fixing device (not shown).

The optical systems 2 to 7, the transfer drum 15, and the photosensitive drum 8 are driven by motors M1, M2, M3, respectively, and the motors M1, M2, M3 are controlled by a motor control unit 30 and a motor drive unit 31 through a control circuit. The CPU 40 is controlled by a main body CPU 41 and a servo CPU 42 (described later). The speeds and positions of the optical systems 2 to 7, the photosensitive drum 8, and the transfer drum 15 are fed back to the control circuit 40 via the motor control unit 30 and the motor drive unit 31. Further, the leading and trailing edges of the recording paper are detected by the sensor S1, and the control circuit 40 increases the speed of the transfer drum 15 in the non-transfer area according to the detection signal.

Next, the configuration and operation of a color copying machine using the image forming apparatus of this embodiment will be described with reference to FIG. A document image on the platen 1 is guided to a color separation filter 7 by a first mirror 2, a second mirror 3, a third mirror 4, a lens 5, and a fourth mirror 6, and R, G, B by the color separation filter 7. And an electrostatic latent image of each color is formed on the photosensitive drum 8.

The photosensitive drum 8 rotates in the clockwise direction in the figure, and the charging drum 9, the eraser 10, and the B / W developing roller 1 for black and white copying are rotated around the photosensitive drum 8 in the rotating direction.
1. A yellow developing roller 12 for color copying, an M developing roller 13 for magenta, a C developing roller 14 for cyan, and a transfer drum 15 are sequentially arranged.

The transfer drum 15 rotating in the counterclockwise direction shown in FIG.
It rotates, and the three color toner images on the photosensitive drum 8 are superimposed and transferred onto the recording paper. Around or inside the transfer drum 15, the transfer charger 16, the separation charger 17, the AC neutralization chargers 18, 19, D
The C neutralization chargers 20 and 21 are arranged in this order.

This color copying machine has an operation section 22 as shown in FIG. 3, and a start key 2 for starting copying.
3 or key 2 to select black and white copy or color copy
4 and so on. Therefore, when the start key 23 is pressed after the black and white copy is selected by the key 24, the document image on the document table 1 is scanned once by the optical systems 2 to 7 in FIG. Then, a black and white toner image is formed on the photosensitive drum 8 and
It is transferred to the recording paper by rotation.

On the other hand, when the start key 23 is pressed after the color copy is selected by the key 24, the color original image on the original table 1 is scanned three times by the optical systems 2 to 7 and the photosensitive drum 8 is rotated three times. And yellow, magenta,
A cyan toner image is formed on the photosensitive drum 8. When the transfer drum 15 around which the recording paper is wound rotates three times, the three toner images are superimposed and transferred onto the recording paper.
Therefore, in the case of this color copying, the transfer speed is increased in the non-transfer area until the leading end returns to the position of the transfer charger 16 after the trailing edge of the recording paper has passed the position of the transfer charger 16 to increase the CPM or the like. Efficiency can be improved.

Referring to FIG. 4, a control circuit 40 of the copying machine
Is a main body CP for controlling the entire copying machine as shown in FIG.
U41 and a motor M for driving the optical systems 2 to 7, the photosensitive drum 8, and the transfer drum 15 as shown in FIG.
1, a servo CPU 42 for controlling M2 and M3. The programs of the main CPU 41 and the servo CPU 42 are respectively provided in a ROM (read only memory) 41.
a, 42a, and RAMs (random access memories) 41b, 42b
41, a work area for the servo CPU 42 is provided.

The main body CPU 41 transmits a speed increase start signal of the transfer drum 15 to the servo C via the dual port RAM 43.
When the signal is output to the PU 42, the servo-side CPU 42 outputs the motor control unit 30 and the motor drive unit 31
When the speed of the transfer drum 15 is increased via the motor M2 and the speed increase is detected by the feedback signal from the motor M2, the state signal is output to the main body CPU 41 via the dual port RAM 43. Also, the servo side CP
When U42 detects the end of the speed increase of the transfer drum 15, the state signal is transmitted to the main body CPU via the dual port RAM 43.
41, the main body CPU 41 determines that the transfer charger 16 and the AC charge removing chargers 18, 19, D
The output of the C neutralization chargers 20 and 21 is controlled.

Next, the operation of the above embodiment, in particular, the operation of the main CPU 41 and the servo CPU 42 will be described with reference to FIGS. In FIG. 5, after the initialization (Step S1), the main body CPU 41 starts copying (Step S2), executes a speed increase start control routine as shown in detail in FIG. 7 (Step S3), and then proceeds to FIG. A transfer drum speed increase monitoring control routine as shown in detail is executed (step S4), and a transfer neutralization ON control routine as shown in detail in FIG. 10 is executed (step S5). Then, FIG.
A transfer static elimination output switching control routine as shown in detail in FIG. 1 is executed (step S6), and a transfer static elimination off control routine as shown in detail in FIG. 12 is executed (step S6).
7). When the second and third toner images are to be transferred, the process returns to step S3 to repeat this process. When the transfer of the last toner image is completed (step S8), the process returns to step S2.

In FIG. 6, after initialization (step S11), the servo CPU 42 executes a transfer drum drive control routine (step S12), and then executes a photosensitive drum drive control routine (step S13) to control scanner drive. A routine is executed (step S14), and then a transfer drum speed-up state signal control routine as shown in detail in FIG. 8 is executed (step S15), and step S1 is executed.
Return to 2.

In the speed increasing start control routine shown in step S3 of FIG. 5, as shown in detail in FIG.
When the sensor S1 detects the trailing edge of the recording sheet, the process proceeds from step S31 to step S32, and outputs a speed increase start signal of the transfer drum 15.

In the transfer drum speed-up state signal control routine shown in detail in FIG.
The rotation speed of the transfer drum 15 is increased by the speed increase start signal from U41, and in step S151, the motor M
It is determined whether or not the speed increase has been started based on the feedback signal from the control unit 2.
Proceed to 152. Next, if the speed increase of the transfer drum 15 has not been completed, steps 152 to S153 are performed.
Then, the position of the transfer drum 15 is corrected by the feedback signal from the motor M2, and in a succeeding step S154, the transfer drum speed-up state signal is turned on and the process returns.

On the other hand, if the speed increase of the transfer drum 15 has been completed in step S152, the process proceeds to step S155.
Then, it is determined whether or not the positional deviation of the transfer drum 15 at the start of the speed increase is within a certain range based on the feedback signal from the motor M2. If the positional deviation of the transfer drum 15 at the start of the speed increase is not within a certain range, the process returns to step S151, and if it is within a certain range, the process proceeds to step S156.
The transfer drum speed-up state signal is turned off, and then the speed-up of the transfer drum 15 is terminated (step S157).

In the transfer drum speed-up monitoring control routine shown in step S4 of FIG. 5, as shown in detail in FIG. 9, the main body CPU 41 firstly increases the speed of the transfer drum 15 based on the transfer drum speed-up state signal from the servo CPU 42. Is determined (step S41), and if the speed increase is not started, the process branches to step S42 to reset a flag indicating an abnormality of the transfer drum 15. If the speed increase of the transfer drum 15 has started normally, the process proceeds to step S43, and it is determined whether the servo CPU 42 has started monitoring the speed increase of the transfer drum 15.

If the servo CPU 42 has started monitoring the speed increase of the transfer drum 15, the process advances from step S43 to step S44 to determine whether or not the timer value after the start of the speed increase monitoring is equal to or longer than a predetermined time t1. . The predetermined time t1
Similarly, in the case of the black-and-white mode and the case of the full-color mode, the speed-up usually ends in about 400 ms.
It is set to about 0 ms. When the timer value reaches a predetermined time t1
If the timer value is less than the predetermined time t1, the process proceeds to step S45, where a flag indicating an abnormality of the transfer drum 15 is set, and the transfer drum 15 is stopped and notified.

In step S43, the servo CP
If U42 has not started monitoring the speed increase of the transfer drum 15, the process branches to step S46 to start monitoring the speed increase, and then the timer is started (step S4).
6).

In the transfer static elimination ON control routine shown in step S5 in FIG. 5, as shown in detail in FIG. 10, the timing for turning on the outputs of the AC static elimination chargers 18 and 19 and the DC static elimination chargers 20 and 21 of the transfer drum 15 is determined. It is determined whether or not the transfer drum 15 is turned on with a relatively high current, for example, 50 μA corresponding to the case where the speed of the transfer drum 15 is increasing (step S5).
2).

In the transfer static elimination output switching control routine shown in step S6 of FIG. 5, as shown in detail in FIG.
AC neutralization chargers 18 and 19, DC neutralization charger 2
It is determined whether the outputs 0 and 21 are on (step S).
61) If it is in the ON state, the process proceeds to step S62, and it is determined whether or not the speed increase of the transfer drum 15 has been completed based on the transfer drum speed increase state signal from the servo CPU 42. If the speed increase of the transfer drum 15 has not been completed, step S
Returning to step 61, the relatively high current is continued, and when the acceleration is completed, the process proceeds to step S63, where the relatively low current, for example, 20 μm
At A, the outputs of the AC neutralization chargers 18 and 19 and the DC neutralization chargers 20 and 21 are turned on.

In the transfer static elimination off control routine shown in step S7 of FIG. 5, as shown in detail in FIG. 12, the AC static elimination chargers 18, 19 and the DC static elimination chargers 20, 21 are provided.
It is determined whether or not it is time to turn off the output (step S71), and if so, it is turned off (step S72).

Therefore, according to the above embodiment, when increasing the speed of the transfer drum 15 in the non-transfer area, the main body CPU 41 instructs the speed increase as shown in FIG. 7 and the servo CPU 41 as shown in FIG. Transfer drum 15 by command
The speed of the transfer drum 15 is monitored by monitoring the speed-up state. If the speed-up state is abnormal, the main body CPU 41 operates as shown in FIG.
Since the rotation of the paper is stopped and information is notified, jams and I
C can be prevented from being destroyed.

According to the above embodiment, the transfer drum 1
The speed increasing state of No. 5 is monitored, and in the speed increasing state, the static elimination is performed by driving the AC static elimination chargers 18 and 19 and the DC static elimination chargers 20 and 21 with a relatively high current according to the speed as shown in FIG. After the end of the speed increase, as shown in FIG.
Since the static elimination chargers 18 and 19 and the DC static elimination chargers 20 and 21 are driven by a relatively low current according to the speed to perform static elimination, it is possible to prevent static elimination unevenness.

In the above embodiment, the transfer drum 15 around which the recording paper is wound has been described as an example.
Alternatively, the present invention can be applied to an intermediate transfer medium on which a toner image on a photosensitive drum is transferred intermediately.

[0037]

[0038]

According to the first aspect of the present invention, the transfer medium is discharged to the same potential when the monitoring means detects the speed increase state of the transfer medium and when the speed increase is completed. Since the output of the charge-removing charger is controlled by the charge-removing control means, the transfer medium is discharged to the same potential regardless of whether the transfer medium is in a speed-up state or when the speed-up is completed, thus preventing abnormal images. can do.

According to the second aspect of the present invention, when the rotation abnormality of the transfer medium is detected, the rotation of the transfer medium is stopped and the abnormality is notified, so that the jam of the recording paper and the destruction of the IC can be prevented. it can. According to the third aspect of the present invention, since the transfer medium comprises a transfer drum around which a recording paper is wound, the effects of the first and second aspects of the present invention can be obtained in an image forming apparatus of this type.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a cross-sectional view illustrating a color copying machine in which the image forming apparatus of FIG. 1 is used.

FIG. 3 is a plan view showing an operation unit of the color copying machine shown in FIG. 2;

FIG. 4 is a block diagram illustrating a detailed configuration of a control circuit in FIG. 1;

FIG. 5 is a flowchart for explaining main operations of a main body CPU of FIGS. 1 and 4;

FIG. 6 is a flowchart for explaining main operations of a servo-side CPU in FIGS. 1 and 4;

FIG. 7 is a flowchart illustrating a detailed operation of a speed increase start control routine of FIG. 5;

FIG. 8 is a flowchart illustrating a detailed operation of a transfer drum speed-up state signal control routine of FIG. 6;

FIG. 9 is a flowchart illustrating a detailed operation of a transfer drum speed increase monitoring control routine of FIG. 5;

FIG. 10 is a flowchart illustrating a detailed operation of a transfer static elimination ON control routine of FIG. 5;

FIG. 11 is a flowchart illustrating a detailed operation of a transfer static elimination output switching routine in FIG. 5;

FIG. 12 is a flowchart illustrating a detailed operation of a transfer static elimination off control routine of FIG. 5;

[Explanation of symbols]

 Reference Signs List 15 Transfer drum 19, 20, 21 Static elimination charger 30 Motor control unit 31 Motor drive unit 40 Control circuit 41 Main unit CPU 42 Servo CPU M2 Motor

Claims (3)

(57) [Claims] 1. An image forming apparatus for transferring a toner image onto recording paper using a transfer medium, comprising: a transfer medium driving means for driving the transfer medium to rotate; and a rotation medium for increasing the rotation speed of the transfer medium in a non-transfer area. Command means for generating a command; drive control means for controlling the transfer medium drive means to increase the rotation speed of the transfer medium in accordance with the command from the command means; and rotational state of the transfer medium speeded up by the drive control means Monitoring means for monitoring the transfer medium, a charge elimination charger for discharging the transfer medium after transfer, and a case where the monitoring means detects a speed-up state of the transfer medium.
When the speed increase is completed, the transfer medium is set to the same potential.
Controlling the output of the static elimination charger so that static elimination is performed
An image forming apparatus , comprising: a static elimination output control unit . 2. The rotation of the transfer medium by the monitoring means.
If an abnormality is detected, stop the rotation of the transfer medium,
The image form according to claim 1, wherein the abnormality is notified.
Equipment. 3. The transfer medium on which recording paper is wound.
3. A drum according to claim 1 or 2,
Image forming apparatus.