JP4414635B2 - Toner discharge method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cleaning method in an image forming apparatus.
[0002]
[Prior art]
In an image forming apparatus such as a printer or a copying machine, an electrophotographic method is increasingly used because of a high printing speed and good storability of a printed image.
[0003]
In an electrophotographic image forming apparatus, a toner made of powdered resin is used as a developer, which is uniformly leveled on the developing roller of the developing apparatus, and the uniformly leveled toner is selectively selected from the developing roller. Then, it is attached to a photosensitive member such as a photosensitive drum and then transferred onto a printing medium such as paper to form an image. This image is fixed on the print medium by a heat fixing device.
[0004]
[Problems to be solved by the invention]
The toner used in such an electrophotographic image forming apparatus has a physical pressure and frictional heat associated with the physical pressure when uniformly leveled on the developing device as described above. The toner is not transferred from the toner and is destroyed by the physical pressure during friction between each roller or the frictional heat associated therewith, or it is pressed against other toner to be integrated into a large lump and printed. Deteriorates as it progresses. Such deteriorated toner accumulates in the developing device, causing problems such as non-uniform image density, reduced dot reproducibility, or so-called fogging in the printed image.
[0005]
[Means for Solving the Problems]
The present invention relates to a toner discharging method applied to an image forming apparatus having a photosensitive member, a charging device, an electrostatic latent image writing device, a developing device, a transfer device, and a cleaning device, and when the photosensitive member reaches a predetermined number of rotations. As the toner discharging operation, the photosensitive member is charged by the charging device, and the photosensitive member reaches the predetermined rotational speed when the photosensitive member is rotated by the predetermined rotational speed at a predetermined printing duty. A difference amount with respect to the number of printed dots printed so far, and the electrostatic latent image writing device writes an electrostatic latent image pattern on which the toner corresponding to the difference amount adheres to the charged photosensitive member, and the developing device The toner is discharged from the developing device by supplying the toner to the photosensitive member from the developing device, and a voltage having the same polarity as the toner is applied to the transfer device. A toner discharge method characterized by removing the toner from the photoreceptor by contacting the grayed device to the photosensitive member.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
(Description of image forming apparatus)
FIG. 1 is a diagram illustrating a main part of an image forming apparatus for illustrating the first embodiment. The image forming apparatus 100 includes a drum-type image carrier (hereinafter referred to as a photosensitive drum) 101, a conductive rubber roller (hereinafter referred to as a charging roller) 102 that rotates in contact with the photosensitive drum 101, and a photosensitive member. An electrostatic latent image writing device 103 that selectively exposes the drum 101, a toner regulating member 104 that keeps the toner amount on the developing roller constant, and a toner carrier that supplies toner to the photosensitive drum (hereinafter referred to as a developing roller). 105) 105, a supply roller 106 that supplies toner to the developing roller, a cleaning blade 107 that scrapes residual toner on the photosensitive drum 101, a transfer roller 108 that transfers toner to the recording paper 111, and a transfer belt that conveys the recording paper 111 110 and a charging roller 102, a developing roller 105, a supply roller 106, and a transfer roller 108 that supply voltage to the transfer roller 108 (not shown). It is composed of a not shown control unit for controlling the respective units and.
[0009]
As the photosensitive drum 101, for example, an organic photosensitive drum is used. As the charging roller 102, a silicone resin or a urethane resin roller can be used. The electrostatic latent image writing device can use a laser or a light emitting diode (LED) array head. The developing roller 105 can use silicone resin or urethane resin. The supply roller 106 can use foamed resin such as urethane.
[0010]
A toner cartridge 113 that supplies toner to the developing device 109 is detachably connected to the developing device 109 including the toner regulating member 104, the developing roller 105, and the supply roller. The toner cartridge 113 has a waste toner container 114 therein, and the collected waste toner can be taken out from the image forming apparatus 100 simultaneously with the replacement of the toner cartridge.
[0011]
As the toner supplied from the toner cartridge, for example, a capsule toner having a particle diameter of 5 to 7 μm can be used. For example, the capsule toner is configured so that it melts easily at high temperatures during fixing, but does not easily fuse with the surrounding toner during storage by enclosing the resin with a low glass transition temperature on the inside with a resin with a high glass transition temperature on the outside. Has been.
[0012]
The control unit (not shown) of the image forming apparatus 100 is provided with a counter that counts the number of printed sheets.
[0013]
Next, the operation will be described. The photosensitive drum 101, the rollers 102, 105, and 108 and the transfer belt 110 are rotationally driven by a motor (not shown), and the recording paper 111 is fed by a paper feeding mechanism (not shown). The photosensitive drum 101 rotates in the direction of arrow A, the charging roller 102 rotates in the direction of arrow B, the developing roller 105 rotates in the direction of arrow C, the transfer belt 110 rotates in the direction of arrow D, and the recording paper 111 Is assumed to travel in the direction of arrow E.
[0014]
(Printing operation)
First, the photosensitive drum 101 is uniformly charged to a predetermined surface potential, for example, −850 V by contact with the charging roller 102 when the charging roller 102 is supplied with a negative voltage of, for example, −1350 V from a power supply device (not shown). The The uniformly charged surface of the photosensitive drum 101 reaches below the electrostatic latent image writing device 103 due to the rotation in the arrow A direction. Depending on the image to be formed, the electrostatic latent image writing device 103 selectively exposes the surface potential of the photosensitive drum 101 in the portion where the electrostatic latent image is written, which is about −50 V. Is also close to 0V.
[0015]
The surface of the photosensitive drum 101 that has completed writing of the electrostatic latent image comes into contact with the developing roller 105 by the rotation in the arrow A direction. The developing roller 105 contacts the photosensitive drum 101 with a predetermined pressure and rotates in the direction of arrow C. The toner on the developing roller 105 is thinned by the toner regulating member 104, and moves on the photosensitive drum 101 by contact with the photosensitive drum 101 by the rotation of the developing roller 105 to perform development. Here, the developing method is reversal development in which the toner has a charge of the same polarity as that of the uniformly charged polarity of the photosensitive drum 101, and a negative voltage is applied to the developing roller 105 from a power source (not shown). The toner is developed on the photosensitive drum 101.
[0016]
The surface of the photosensitive drum 101 that has been developed comes into contact with the transfer belt 110 by the rotation in the arrow A direction. The transfer belt 110 is configured to contact the photoconductor 101 with a predetermined pressure and move in the direction of arrow D at the same speed. A positive voltage of +1500 V, for example, is supplied to the transfer belt 110 by a power source (not shown), and the toner on the photosensitive drum 101 is transferred by moving to the recording paper 111 traveling in the direction of arrow E. The recording paper 111 after transfer is separated from the photosensitive drum 101.
[0017]
As shown in FIG. 2, in the case of a tandem type color printer, four image forming apparatuses a, b, c, and d in FIG. 1 are arranged, and after the transfer of the image forming apparatus d is completed, it is inserted into a fixing device (not shown) and fixed. After completion, the printed matter is discharged out of the image forming apparatus.
[0018]
After the transfer is completed in the image forming apparatus of FIG. 1, a part of the toner remains as untransferred toner on the surface of the photosensitive drum 101, but the surface of the photosensitive drum 101 continues to be untransferred by rotation in the direction of arrow A. It contacts the cleaning blade 107 together with the toner. Untransferred toner on the photosensitive drum 101 is scraped off by the cleaning blade 107. That is, the untransferred toner is removed from the photosensitive drum 101. The photosensitive drum 101, from which the untransferred toner has been removed, continues to rotate in the direction of arrow A and enters the charging process again.
[0019]
(Toner discharge operation)
FIG. 3 is a time chart for explaining the toner discharging operation. In the figure, a103 to d103 respectively indicate the development timing of the electrostatic latent image writing device 103 of the image forming apparatuses a to d, and a, b, c, d102, a, b, c, d105, a, b, c, d106 indicates the voltages of the charging roller 102, the developing roller 105, and the supply roller 106, respectively, and a, b, c, and d108 indicate the voltages of the transfer rollers 108 of the image forming apparatuses a to d, respectively. Here, for example, a toner discharge operation is performed after exposing a predetermined number N of print data.
[0020]
Immediately after the Nth exposure of the image forming apparatus d in FIG. 2 is completed, the exposure unit 103 of the image forming apparatus a starts the exposure. The exposure time L1 is determined by an arbitrary toner discharge amount.
[0021]
The voltage applied to the transfer roller 108 of the image forming apparatus a indicated by a108 at time t2 when the time L5 immediately before the surface of the photosensitive drum 103 at the exposure start time t1 indicated by a103 contacts the transfer belt 110 has elapsed is 0V. Become. For this reason, most of the toner adhering to the photosensitive drum 101 continues to adhere to the photosensitive drum 102 even after passing through the transfer belt. The toner adhering to the photosensitive drum is scraped off by the cleaning blade 107 and stored in a cleaning device that stores the cleaning blade 107 .
[0022]
On the other hand, the voltage applied to the transfer roller 108 becomes a minus voltage of −400 V from time t2 to time L1. The time during which the negative voltage is turned off is applied negatively while the toner on the photosensitive drum 101 is in contact with the transfer belt, so that the negative application time should be longer before and after the normal L1. preferable. Note that although the transfer is slight even at 0 V, the toner can be maintained in a state where it is generally attached to the photosensitive drum 101. Therefore, the discharge voltage can be selected from 0V to -400V.
[0023]
Further, when the toner partially attached to the transfer belt passes through the image forming apparatuses b, c, and d, a standby voltage is supplied to the transfer roller 108 of each image forming apparatus. The standby voltage takes a value between 0 V and the transfer voltage. By applying the transfer voltage, the influence on the photosensitive drum is suppressed as much as possible, and the toner adhering to the transfer belt is held and the image is held. Reattachment of the forming apparatuses b, c, d to the photosensitive drum 101 is suppressed.
[0024]
As shown at b103, the exposure unit 103 of the image forming apparatus b performs the time t4 when the time L6 when the transfer belt moves from the image forming apparatus a to the image forming apparatus b has elapsed from the time t3 when the exposure of the image forming apparatus a ends. Start exposure. Thereafter, the same operation as that of the image forming apparatus a is performed.
[0025]
The exposure unit 103 of the image forming apparatus c starts exposure at time t7 when the time L7 when the transfer belt moves from the image forming apparatus b to the image forming apparatus c elapses from time t6 when the exposure of the image forming apparatus b ends. Thereafter, the same operation as that of the image forming apparatus a is performed.
[0026]
The exposure unit 103 of the image forming apparatus d starts exposure at time t10 when the time L8 when the transfer belt moves from the image forming apparatus c to the image forming apparatus d elapses from time t9 when the exposure of the image forming apparatus c ends. Thereafter, the same operation as that of the image forming apparatus a is performed.
[0027]
Through the above operation , waste toner can be collected in the waste toner container 114 of the toner cartridge 113.
[0028]
(Effects of the first embodiment)
As described above, the deteriorated toner in the developing device is discharged onto the photosensitive drum 101 by the operation of the first embodiment, so that the discharged toner is discharged to the waste toner box on the photosensitive member side, particularly the waste toner container in the toner cartridge. It is possible to collect the image, and it is possible to prevent image deterioration due to deteriorated toner accumulated in the developing device, particularly around the toner regulating member.
[0029]
In the present embodiment, particularly, the deteriorated toner is collected in a waste toner container in the toner cartridge. Therefore, the discharged deteriorated toner is replaced at the same time as the replenishment of the toner. there is no possibility that the waste toner overflows from the waste toner container even if the large amount of emissions.
[0030]
This eliminates the need to extremely increase the capacity of the waste toner box on the transfer belt side.
[0031]
(Second Embodiment)
In a first implementation embodiment has been described a case of ejecting the toner unconditionally all the image forming apparatus to d. However, in practice, or if the print duty high is discharged is developed before the toner is deteriorated, because even if degraded is discharged been developed with other normal toner, the toner discharge is not required.
[0032]
In this embodiment, the toner is discharged according to the time chart of FIG. 3, and the toner discharge is adjusted as follows. The control unit (not shown) of the image forming apparatus shown in FIG. 1 includes a counter for counting the number of rotations of the photosensitive drum and a counter for counting printing dots in addition to the counter for counting the number of printed sheets.
[0033]
(Toner discharge operation)
FIG. 4 is a flowchart for the toner ejection.
[0034]
In FIG. 4, p is a counter value obtained by counting the number of rotations of the photosensitive drums of the image forming apparatuses a to d, d is a counter value obtained by counting the number of printed dots, and Cp is a predetermined value for the number of rotations of any photosensitive drum. Is defined as Cd, and the difference between the specified dot number and the dot number counter value is dif.
[0035]
In s1, the rotation of the photosensitive drum is detected. When the photosensitive drum starts to rotate, the process proceeds to the next step.
[0036]
In s2, the number of revolutions of the photosensitive drum is counted by the counter p.
[0037]
In s3, the number of print dots is counted in the counter d.
[0038]
In s4, it is determined whether or not the value of the photosensitive drum rotation number counter reaches an arbitrarily determined photosensitive drum rotation number count Cp. If not, return to s1. If so, go to s5.
[0039]
In s5, it is determined whether the print dot number counter value c has reached an arbitrary specified dot number Cd. The value of Cd is a dot number count value when the photosensitive drum is rotated by p at the required printing duty. If so, go to s8. If the printing dot number counter value c has not reached the arbitrary prescribed dot number Cd in s5, the process proceeds to s6.
[0040]
In s6, a difference dif between the specified dot number Cd and the print dot number counter value c is obtained.
[0041]
In s7, the toner discharge sequence (Example 1) is entered at the break of printing, and dif toner is discharged. When toner ejection is completed, the process proceeds to s8.
[0042]
In s8, the count value p of the photosensitive drum rotation number counter and the count value d of the printing dot number counter are cleared, and the process proceeds to s1.
[0043]
The above flow is performed for each of the image forming apparatuses a to d.
[0044]
(Effect of the second embodiment)
As described above, according to the second embodiment, toner is discharged by a difference that has not been reached to an image forming apparatus that has not reached the average duty with respect to a predetermined number of rotations of the photosensitive drum. Things will be possible. For this reason, it is possible to effectively discharge the deteriorated toner but reduce the discharge of the toner that has not deteriorated.
[0045]
(Modification of the embodiment)
In the first embodiment, the toner discharge sequence is described. In the second embodiment, the toner discharge algorithm is described. However, when toner is simply ejected, the amount of toner consumption increases, which is uneconomical. In the third embodiment, a toner discharge pattern for suppressing toner consumption will be described.
[0046]
In the third embodiment, the control unit of the image forming apparatus includes a storage unit that stores a predetermined print pattern. FIG. 5 is an example of a toner discharge pattern.
[0047]
As shown in FIG. 5, when toner is discharged, a deteriorated toner can be effectively discharged by performing a 100% discharge pattern on the entire surface. However, there is a position where the toner is likely to be deteriorated depending on a portion where the toner is used and a state of recirculation of toner in the developing device. If 100% ejection is performed even at a position where toner deterioration is small, excess toner is ejected. Further, if more toner is ejected due to a portion where the toner is severely deteriorated, a portion where there is not much toner deterioration further consumes extra toner.
[0048]
The toner deterioration state in each part will be described more specifically. FIG. 6 is an example of a printing result when a half pattern is printed with a configuration used over time. In the print end portion 601, non-uniform image density and low dot reproducibility are likely to occur.
[0049]
In order to reduce the phenomenon of FIG. 6, the discharge portion is divided into 701a, 701b and 701c as shown in FIG. As an example, in FIG. 7, 100% toner discharge is performed on the portions 701a and 701c which are the end portions of the printable area, and 50% toner discharge is performed on the central portion 701b. .
[0050]
As described above, by increasing the duty at the end of the printable area and decreasing the duty at the center, the discharged toner can be efficiently discharged by discharging a larger amount of the toner at the end with much deteriorated toner. it can.
[0051]
【The invention's effect】
As described above, according to the present invention, toner with deteriorated toner can be effectively discharged, so that it is possible to suppress non-uniform image density on printing and a decrease in dot reproducibility.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part for explaining an image forming apparatus used in a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of a main part when the first embodiment of the present invention is configured in a color printer.
FIG. 3 is a timing chart for explaining the operation of the first exemplary embodiment of the present invention.
FIG. 4 is a flowchart for explaining a second embodiment of the present invention;
FIG. 5 shows an example of a toner discharge pattern in the present invention.
FIG. 6 shows an example of a printing state.
FIG. 7 shows a modified example of a print pattern used in the present invention.
[Explanation of symbols]
100: Image forming apparatus 101: photosensitive drum 102: charging roller 103: electrostatic latent image writing device 104: toner regulating member 105: the developing roller 106: feed roller 107: a cleaning blade 108: transfer roller 109: developing equipment 113: Toner cartridge 114: waste toner container

Claims (2)

In a toner discharging method applied to an image forming apparatus having a photoreceptor, a charging device, an electrostatic latent image writing device, a developing device, a transfer device, and a cleaning device,
When the photosensitive member reaches a predetermined rotational speed , as a toner discharging operation,
Charging the photoreceptor with the charging device;
Calculating the amount of difference between the prescribed number of dots when the photosensitive member is rotated by the predetermined rotational speed at a predetermined printing duty and the number of printed dots printed until the photosensitive member reaches the predetermined rotational speed ;
Write an electrostatic latent image pattern in which the difference amount of toner adheres to the charged photosensitive member by the electrostatic latent image writing device;
The toner is discharged from the developing device by supplying toner from the developing device to the photosensitive member and developing the toner,
Apply a voltage of the same polarity as the toner to the transfer device,
A toner discharging method comprising: removing toner from the photosensitive member by bringing the cleaning device into contact with the photosensitive member. The toner discharging method according to claim 1.
The toner discharging method according to claim 1, wherein the electrostatic latent image pattern has a larger number of print dots at a print area end than at a print area center.

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