JP2004170474A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and an image forming method which efficiently reduce ununiform discharge which occurs immediately after cleaning of an electrifying part. <P>SOLUTION: The image forming apparatus includes the electrifying part which electrifies an image carrier by discharge, a cleaning part which cleans the electrifying part, a power source part which supplies a current to the electrifying part, and a control part which controls the power source part, The control part controls the power source part (S3 to S8) so that a current is supplied to the electrifying part after the cleaning of the electrifying part is finished (S2) and before an image is formed on the image carrier (S10). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus and an image forming method such as a copying machine, a printer, a facsimile, and a multifunction peripheral thereof, and more particularly, to an image forming apparatus and an image forming method having a charging unit that charges an image carrier by discharging. It is about.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, a charging unit (charging device) for charging an image carrier such as a photosensitive drum by corona discharge has been often used (for example, see Patent Document 1).
[0003]
Specifically, the charging section mainly includes a wire as a corona discharge electrode (discharge member) to which a high voltage is applied, a shield electrode facing the corona discharge electrode, and the like. Then, a corona discharge occurs due to the formation of a strong electric field between these electrodes. Further, the surface of the image carrier is charged by the charge generated by the corona discharge.
[0004]
It is known that, in a charging unit using such corona discharge, dust adheres to the surface of the discharge member due to long-term use, causing uneven discharge.
More specifically, since an electrostatic dust collecting action acts on the surface of the discharge member of the charging unit, dust such as floating toner adheres to the discharge member. Then, due to long-term use of the charging unit, dust adhering to the surface of the discharge member accumulates, preventing uniform discharge.
When the discharge unevenness occurs as described above, the surface of the image carrier such as the photosensitive drum is not uniformly charged, and the image density unevenness occurs in the toner image formed in the subsequent image forming process.
[0005]
For the purpose of reducing such image density unevenness, a technique has been disclosed in which a discharging member of a charging unit is periodically cleaned to remove dust adhering to the discharging member.
For example, in Patent Literature 1, the charging unit is provided with a discharge wire cleaning member for cleaning the discharge wire. Then, an interval for cleaning the discharge wire by the discharge wire cleaning member is appropriately set in accordance with a use environment and a use condition in which discharge unevenness is likely to occur.
[0006]
[Patent Document 1]
JP-A-6-282152 (pages 2-3, FIGS. 1, 3)
[0007]
[Problems to be solved by the invention]
The above-described conventional image forming apparatus has a problem that discharge unevenness occurs temporarily immediately after the discharge member is cleaned by the cleaning member. Then, due to the discharge unevenness immediately after the cleaning, remarkable image density unevenness particularly occurred when a halftone image was formed.
[0008]
It is considered that the discharge unevenness immediately after the cleaning is caused by the following two causes.
First, it is considered that the reason is that dust such as toner partially remains when the discharge member is cleaned by the cleaning member. When the dust partially remains on the surface as described above, the remaining portion becomes a protruding state as compared with the portion which has been properly removed, and a local discharge occurs in the remaining portion.
[0009]
Second, it is considered that the reason is that the surface of the discharge member is roughened by cleaning the discharge member by scraping the surface with a relatively rough cleaning member, and minute projections are generated on the surface.
That is, the toner, which is the main dust adhering to the surface of the discharge member, is melted by the discharge and adheres to the surface of the discharge member. Therefore, in order to remove the adhered toner, cleaning is performed such that the toner is scraped off with a cleaning member having a rough surface. At this time, the surface of the discharge member is roughened by the cleaning, and minute projections are generated on the surface. When a minute projection is formed on the surface of the discharge member, a local discharge occurs at the projection.
[0010]
SUMMARY An advantage of some aspects of the invention is to provide an image forming apparatus and an image forming method that can efficiently reduce discharge unevenness that occurs immediately after cleaning of a charging unit.
[0011]
[Means for Solving the Problems]
The inventor of the present application has conducted studies to solve the above-mentioned problems, and as a result, has come to know the following matters.
That is, by discharging the charging unit for a predetermined time after cleaning the charging unit and before forming an image, the above-described temporary discharge unevenness immediately after cleaning is eliminated.
[0012]
This is considered for the following two reasons.
The first is that the toner in a protruding state remaining on the discharge member of the charging unit after cleaning is melted by the discharge, and spreads and adheres along the surface of the discharge member. That is, it is considered that the adhered toner, which was in the protruding state immediately after the cleaning, becomes flat by the subsequent discharge, and the local discharge is eliminated.
[0013]
Secondly, the minute projections formed by cleaning the surface of the discharge member so as to scrape off the surface of the discharge member with a rough surface are deformed into a round shape by the subsequent discharge. In other words, it is considered that the protruding portion that has protruded immediately after cleaning has no sharp portion due to the subsequent discharge, and the local discharge is eliminated.
[0014]
Furthermore, the inventor of the present application has come to know that by adjusting the magnitude of the discharge immediately after cleaning in the charging unit in accordance with the use environment and the use situation, it is possible to efficiently reduce the discharge unevenness after the cleaning. That is, the larger the current supplied to the charging unit, the more stable the discharge and the larger the amount of heat generated, so that the source of the above-mentioned discharge unevenness can be eliminated in a short time.
However, when the discharge current is too large, there is a side effect that products such as ozone and Nox increase and shorten the life of the charging unit. Therefore, by keeping the current supplied to the charging unit to a necessary and sufficient amount according to the degree of occurrence of discharge unevenness immediately after cleaning depending on the use environment or use condition, efficient discharge unevenness can be prevented.
[0015]
The present invention is based on the matters described above. That is, an image forming apparatus according to the first aspect of the present invention includes a charging unit for charging an image carrier by discharging, and a cleaning unit for cleaning the charging unit. And a power supply unit for supplying a current to the charging unit, and a control unit for controlling the power supply unit, wherein the control unit is configured to perform the cleaning after the cleaning unit finishes cleaning the charging unit. Before forming an image on the carrier, the power supply unit is controlled so as to supply a current to the charging unit.
[0016]
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, the image forming apparatus further includes a detecting unit that detects temperature and / or humidity, and the power supply unit supplies a current supplied to the charging unit. The control unit is configured to change the size of the detection unit after the cleaning unit finishes cleaning the charging unit and before forming an image on the image carrier. The power supply unit is controlled so as to vary the magnitude of the current supplied to the charging unit based on the power supply.
[0017]
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the image forming apparatus further includes a time detecting unit configured to detect an accumulated discharging time in the charging unit. Is formed so that the magnitude of the current supplied to the charging unit can be varied, and the control unit forms an image on the image carrier after cleaning of the charging unit by the cleaning unit is completed. Before, the power supply unit is controlled so as to change the magnitude of the current supplied to the charging unit based on the detection result of the time detection unit.
[0018]
An image forming apparatus according to a fourth aspect of the present invention is the image forming apparatus according to any one of the first to third aspects, further comprising a number detecting unit for detecting an accumulated number of cleanings in the cleaning unit, The power supply unit is formed so as to be able to change the magnitude of a current supplied to the charging unit, and the control unit is configured to perform image formation on the image carrier after cleaning of the charging unit by the cleaning unit is completed. Before forming, the power supply unit is controlled so as to vary the magnitude of the current supplied to the charging unit based on the detection result of the number-of-times detecting unit.
[0019]
According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the second to fourth aspects, when the detection result reaches a reference value, the control unit sets The power supply unit is controlled so that a current larger than a current supplied to the charging unit when forming an image on the image carrier is supplied to the charging unit.
[0020]
An image forming method according to a sixth aspect of the present invention is an image forming method comprising: a charging step of discharging a charging unit to charge an image carrier; and a cleaning step of cleaning the charging unit. And a discharging step of discharging the charging section after the cleaning step and before the charging step.
[0021]
An image forming method according to a seventh aspect of the present invention is the image forming method according to the sixth aspect, further comprising a detecting step of detecting temperature and / or humidity, and wherein the discharging step includes a step of detecting a result of the detecting step. And an adjusting step of adjusting the magnitude of the discharge in the charging unit based on the adjustment.
[0022]
An image forming method according to an eighth aspect of the present invention is the image forming method according to the sixth or seventh aspect, further comprising a time detecting step of detecting an accumulated time of performing the charging step. Includes an adjusting step of adjusting the magnitude of discharge in the charging unit based on the detection result of the time detecting step.
[0023]
An image forming method according to a ninth aspect of the present invention is the image forming method according to any one of the sixth to eighth aspects, further comprising a number detecting step for detecting an accumulated number of times the cleaning step is performed. The discharging step includes an adjusting step of adjusting the magnitude of the discharging in the charging unit based on the detection result of the number-of-times detecting step.
[0024]
Further, in the image forming method according to the tenth aspect of the invention, in the invention according to any one of the seventh to ninth aspects, the adjusting step is performed when the detection result reaches a reference value. This is a step of adjusting so that a discharge larger than the discharge in the charging unit in the charging step is generated in the charging unit.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the configuration and operation of the entire color image forming apparatus according to the embodiment will be described with reference to FIG.
[0026]
As shown in FIG. 1, in the image forming apparatus, a photoreceptor belt 1 as an image carrier is disposed to face an intermediate transfer belt 4.
Here, a driving roller 1a and two driven rollers 1b and 1c are disposed on the inner periphery of the photoreceptor belt 1. The photoreceptor belt 1 is stretched and supported by these rollers 1a to 1c. The photoreceptor belt 1 is driven in the direction of arrow A in the figure by the driving roller 1a.
A charging unit 2, a writing unit 3, a magenta developing unit M, a cyan developing unit C, a yellow developing unit Y, a black developing unit K, and a cleaning unit 6 are arranged on the outer periphery of the photoreceptor belt 1.
[0027]
Here, magenta toner, cyan toner, yellow toner, and black toner are stored in the four developing units M, C, Y, and K, respectively. The four developing units M, C, Y, and K move freely toward and away from the photosensitive belt 1 to sequentially form toner images of respective colors on the photosensitive belt 1.
Specifically, when a cyan toner image is formed on the photoconductor belt 1, the cyan developing unit C containing the cyan toner moves so as to approach the photoconductor belt 1. On the other hand, the other developing units M, Y, and K move away from the photoreceptor belt 1.
The toner images of each color thus formed on the photoreceptor belt 1 are sequentially transferred onto the intermediate transfer belt 4 in a superimposed manner.
The charging section 2 in the present embodiment has the configuration shown in FIG. 2, which will be described later in detail.
[0028]
On the other hand, a driving roller 4a, two driven rollers 4b and 4c, an intermediate transfer roller 5, and a transfer opposing roller 8 are disposed on the inner periphery of the intermediate transfer belt 4. The intermediate transfer belt 4 is stretched and supported by these rollers 4a to 4c, 5, and 8. The intermediate transfer belt 4 is driven in the direction of arrow B in the figure by the driving roller 4a.
A transfer roller 7 and an intermediate transfer belt cleaning unit 9 are provided on the outer periphery of the intermediate transfer belt 4.
[0029]
Here, the transfer roller 7 and the intermediate transfer belt cleaning unit 9 are configured to be able to freely contact and separate from the intermediate transfer belt 4. Then, the transfer roller 7 and the intermediate transfer belt cleaning unit 9 are retracted to positions away from the intermediate transfer belt 4 until the desired toner images are overlaid on the intermediate transfer belt 4. Then, after the superposition of the toner images on the intermediate transfer belt 4 is completed, the transfer roller 7 and the intermediate transfer belt cleaning unit 9 move to a position where they come into contact with the intermediate transfer belt 4.
[0030]
Thus, the color toner image on the intermediate transfer belt 4 is transferred onto the transfer material P by the transfer roller 7 in contact with the intermediate transfer belt 4.
Further, the untransferred toner remaining on the intermediate transfer belt 4 after the transfer process is collected by the intermediate transfer belt cleaning unit 9 in contact with the intermediate transfer belt 4.
[0031]
On the other hand, a pair of registration rollers 13, a fixing unit 10, and the like are provided on a transport path of the transfer material P in the image forming apparatus.
The fixing unit 10 includes a heating unit including two rollers 10a and 10c and a belt 10d suspended therebetween, and a pressing roller 10b as a pressing unit. Is fixed.
[0032]
The image forming apparatus configured as described above operates as follows during image formation.
Referring to FIG. 1, photosensitive belt 1 runs in the direction of arrow A in the figure. Then, first, the surface of the photoreceptor belt 1 is charged at a portion facing the charging unit 2. Next, the surface of the photoreceptor belt 1 reaches a portion facing the writing unit 3. Then, an electrostatic latent image corresponding to image information of a desired color among magenta, cyan, yellow, and black is formed on the photoreceptor belt 1 by the exposure light emitted from the writing unit 3.
[0033]
Thereafter, the surface of the photoreceptor belt 1 reaches a portion facing the developing unit corresponding to a desired color among the four developing units M, C, Y, and K. Then, a toner of a corresponding color is supplied to the latent image on the photoreceptor belt 1 from the developing unit. Thus, a one-color toner image is formed on the photosensitive belt 1.
Thereafter, the surface of the photoreceptor belt 1 reaches a portion facing the intermediate transfer belt 4. Then, the toner image formed on the photosensitive belt 1 is transferred onto the intermediate transfer belt 4 by the intermediate transfer roller 5 to which a predetermined voltage is applied.
[0034]
Here, untransferred toner that has not been transferred to the intermediate transfer belt 4 remains on the photoreceptor belt 1 after passing through the portion facing the intermediate transfer belt 4.
Then, the surface of the photoreceptor belt 1 to which the untransferred toner adheres reaches a portion facing the cleaning unit 6. Then, at this position, the untransferred toner is collected in the cleaning unit 6. The toner collected in the cleaning unit 6 is subsequently transported to the storage unit 11.
[0035]
Such a series of processes on the photoreceptor belt 1 is similarly performed for other colors. The toner images formed on the photosensitive belt 1 by sequentially moving the four developing units M, C, Y, and K are transferred onto the intermediate transfer belt 4 in a superimposed manner.
Thereafter, the color toner image formed on the intermediate transfer belt 4 reaches the portion facing the transfer roller 7 by running the intermediate transfer belt 4 in the direction of arrow B. Then, at this position, the toner image is transferred onto the transferred material P.
[0036]
Here, untransferred toner that has not been transferred to the transfer target material P remains on the intermediate transfer belt 4 after passing through the portion facing the transfer roller 7.
Then, the surface of the intermediate transfer belt 4 to which the untransferred toner adheres reaches a portion facing the intermediate transfer belt cleaning unit 9. Then, the untransferred toner is collected in the intermediate transfer belt cleaning unit 9 at this position. The toner collected in the intermediate transfer belt cleaning unit 9 is subsequently conveyed to the round container 12.
Thus, a series of processes on the intermediate transfer belt 4 is completed.
[0037]
On the other hand, the transfer material P fed from a paper feeding unit (not shown) reaches the position of the registration roller pair 13 after passing through the transport roller 15. The transfer target material P that has reached the position of the registration roller pair 13 is conveyed at a suitable timing toward the transfer roller 7 so that the toner image formed on the intermediate transfer belt 4 is transferred.
Thereafter, the transfer material P having passed the position of the transfer roller 7 reaches the position of the fixing unit 10. Then, the toner image on the transfer material P is fixed at this position.
Then, the transfer material P is discharged to the outside of the image forming apparatus via a discharge unit (not shown) after passing through the fixing unit 10.
Thus, a series of image forming processes in the image forming apparatus is completed.
[0038]
Next, the configuration and operation of the charging unit, which is a characteristic part of the present invention, will be described in detail with reference to FIGS.
FIG. 2 is a schematic perspective view showing the charging unit 2 installed in the above-described image forming apparatus.
[0039]
In FIG. 2, reference numeral 1 denotes a photoreceptor belt as an image carrier, 2 denotes a charging unit for charging the photoreceptor belt 1, 2a denotes a wire as a discharge member, 2b denotes a photoreceptor belt provided around the wire 2a. A casing having an opening on the side, 2c is a grid electrode installed in the opening of the casing 2b, 17 is a cleaning section for cleaning the wire 2a, 18 is a power supply section for supplying a current to the wire 2a, and 19 is a power supply section 18 20 is a thermo-hygrometer as a detecting unit for detecting the temperature and humidity in the apparatus, 21 is a discharging time counter as a time detecting unit for detecting the accumulated discharging time of the charging unit 2, and 22 is a cleaning unit. 6 shows a cleaning frequency counter as a frequency detecting unit for detecting the cumulative cleaning frequency of the unit 17.
[0040]
As shown in FIG. 2, the charging unit 2 mainly includes a wire 2a, a casing 2b, and a grid electrode 2c.
The wire 2 a is stretched from one end of the charging unit 2 to the other end corresponding to an image forming area in the width direction of the photoreceptor belt 1. The inner surface of the casing 2b facing the wire 2a functions as a shield electrode.
[0041]
When an image is formed on the photoreceptor belt 1 as described with reference to FIG. 1, a predetermined amount of current is supplied from the power supply unit 18 to the wire 2a. As a result, the wire 2a is discharged, and the surface of the photoreceptor belt 1 is charged via the grid electrode 2c. Thereafter, on the photoreceptor belt 1, a latent image is formed at a position where the exposure light is irradiated, and a toner image is formed at a position of the developing unit.
[0042]
Referring to FIG. 2, cleaning unit 17 is installed on charging unit 2 with wire 2a interposed therebetween. The cleaning section 17 mainly includes a cleaning main section made of a sponge-like elastic material, and a case supporting the cleaning main section. The cleaning main part of the cleaning unit 17 is configured to be impregnated with an abrasive or the like and to be in direct contact with the wire 2a.
Further, the cleaning unit 17 is configured to be able to reciprocate in the direction of arrow C in FIG. 2 by a driving unit (not shown).
[0043]
When an image is formed in the image forming apparatus, the cleaning unit 17 configured as described above is controlled to stop at a position outside the image forming area (a position that does not affect image formation).
When cleaning the wire 2a of the charging unit 2 during non-image formation, the wire 2a reciprocates in the direction of arrow C in FIG. 2 to remove dust adhering to the wire 2a.
Note that the timing of cleaning the charging unit 2 by the cleaning unit 17 can be a known timing, for example, set according to the use environment and use situation of the charging unit 2.
[0044]
Further, the power supply unit 18 is configured so that the magnitude of the current supplied to the wire 2a of the charging unit 2 can be changed.
In addition, the controller 19 controls the charging unit 2 for a predetermined time after the cleaning of the charging unit 2 by the cleaning unit 17 is completed and before the charging process by the charging unit 2 for forming an image on the photosensitive drum 1 is performed. The power supply unit 18 is controlled so as to supply a predetermined amount of current to the charging unit 2. As a result, discharge unevenness immediately after cleaning can be prevented.
[0045]
Here, the discharging process performed immediately after the above-described cleaning is performed by adjusting the magnitude of the discharging in accordance with the use environment and use condition of the charging unit 2 at that time.
Specifically, the absolute humidity in the apparatus is detected by the thermo-hygrometer 20. When the detection result is equal to or less than a predetermined value, it is determined that the reference value has been reached, and a current larger than that at the time of image formation is supplied to the wire 2a. I do. This is because when the amount of water in the air is small, discharge unevenness is likely to occur.
Note that the reference value is a value related to environmental conditions or use conditions obtained based on experimental data in order to efficiently suppress discharge unevenness immediately after cleaning.
[0046]
Similarly, the discharge time counter 21 detects the accumulated time required for the charging process by the charging unit 2, and when the detection result is equal to or more than a predetermined value, it is determined that the current value has reached the reference value, and a current larger than that at the time of image formation is applied. Supply to wire 2a. This is because when the accumulated discharge time becomes longer and the wire 2a deteriorates, discharge unevenness is more likely to occur.
Further, the number of times of cleaning by the cleaning unit 17 is detected by the number-of-times-of-cleaning counter 22, and when the detection result is equal to or greater than a predetermined value, it is determined that the reference value has been reached, and a current larger than that during image formation is supplied to the wire 2a. This is because when the cumulative number of times of cleaning is increased and the damage to the wire 2a is increased, discharge unevenness is likely to occur.
[0047]
The thermo-hygrometer 20 may be, for example, an electric thermo-hygrometer using electric resistance. The discharge time counter 21 is a counting circuit held in the control unit 19, and may use data on the current supply time to the charging unit 2 or data on the drive time of the photoreceptor belt 1 and the number of charging processes. You may. The cleaning number counter 22 is a counting circuit held in the control unit 19, and can use data on the number of times the cleaning unit 17 has been operated by the driving unit.
[0048]
Next, an example of a discharging process immediately after the cleaning of the charging unit 2 will be described with reference to a flowchart of FIG.
First, after image formation is repeated, cleaning of the charging unit 2 is started at a predetermined timing (step S1). When the cleaning process of the charging unit 2 is completed (Step S2), the absolute humidity is detected by the thermo-hygrometer 20 and it is determined whether the detection result is equal to or less than a predetermined value (Step S3).
As a result, when it is determined that the absolute humidity is 4 g / m ³ or less, the power supply unit 18 is controlled so that the discharge current in the discharge step becomes 800 μm (step S4).
[0049]
On the other hand, when it is determined that the absolute humidity is greater than 4 grams / m ³ , it is determined whether the detection result related to the number of charging processes (discharge time) detected by the discharge time counter 21 is equal to or greater than a predetermined value. (Step S5).
As a result, when it is determined that the number of times of the charging process is 50,000 or more, the power supply unit 18 is controlled such that the discharge current in the discharging step becomes 800 μm (step S4).
[0050]
On the other hand, when it is determined that the number of times of the charging process is less than 50,000 times, it is determined whether or not the detection result relating to the number of times of cleaning detected by the number-of-times-of-cleaning counter 22 is equal to or more than a predetermined value (step S6).
As a result, when it is determined that the number of times of cleaning is 50 times or more, the power supply unit 18 is controlled so that the discharge current in the discharge step becomes 800 μm (step S4).
On the other hand, when it is determined that the number of times of cleaning is less than 50 times, the power supply unit 18 is controlled so that the discharge current in the discharge step becomes 500 μm (step S7).
[0051]
Thereafter, the discharge before image formation in the charging unit 2 is started by the discharge current set in step S4 or step S7 (step S8).
After the discharge for a predetermined time is completed, the power supply unit 18 is controlled so that the discharge current at the time of image formation becomes 500 μm (step S9).
Thus, a series of discharging steps is completed (Step S10), and thereafter, normal image formation (charging step) is performed.
[0052]
As described above, in the present embodiment, the discharge of the charging unit 2 performed immediately after cleaning is adjusted to a necessary and sufficient magnitude in accordance with the use environment and the use condition of the charging unit 2, so that the side effect Generation can be suppressed, and the source of discharge unevenness immediately after cleaning can be efficiently removed in a short time.
[0053]
In the present embodiment, the configuration of the charging unit 2 is that of a scorotron charger. However, the present invention can be applied to a charging unit having another configuration such as a corotron charger.
In addition, the present invention can be applied to a transfer unit and a static elimination unit that use a corona discharge and have a cleaning unit for a discharge member.
[0054]
It is to be noted that the present invention is not limited to the above-described embodiment, and it is apparent that the embodiment can be appropriately modified within the scope of the technical idea of the present invention, in addition to the suggestions in the embodiment. Further, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to numbers, positions, shapes, and the like suitable for carrying out the present invention.
[0055]
【The invention's effect】
Since the present invention is configured as described above, it is possible to provide an image forming apparatus and an image forming method that can efficiently reduce discharge unevenness that occurs immediately after cleaning of a charging unit.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic perspective view showing a charging unit in the image forming apparatus of FIG.
FIG. 3 is a flowchart illustrating control in the image forming apparatus of FIG. 1;
[Explanation of symbols]
1 photoreceptor belt (image carrier),
2 charging unit, 2a wire, 2b casing, 2c grid electrode,
3 writing section, 4 intermediate transfer belt, 7 transfer roller, 10 fixing section,
17 cleaning unit, 18 power supply unit, 19 control unit,
20 temperature and humidity meter (detection unit), 21 discharge time counter (time detection unit),
22 cleaning frequency counter (frequency detection unit)
K, Y, C, M development section.

Claims (10)

A charging unit that charges the image carrier by discharging,
A cleaning unit for cleaning the charging unit;
A power supply unit for supplying a current to the charging unit;
A control unit for controlling the power supply unit,
The control unit controls the power supply unit so as to supply a current to the charging unit after the cleaning of the charging unit by the cleaning unit is completed and before an image is formed on the image carrier. An image forming apparatus comprising: Further comprising a detection unit for detecting the temperature or / and humidity,
The power supply unit is formed so as to be able to vary the magnitude of the current supplied to the charging unit,
The controller is configured to control a current supplied to the charging unit based on a detection result of the detection unit after the cleaning of the charging unit by the cleaning unit is completed and before an image is formed on the image carrier. The image forming apparatus according to claim 1, wherein the power supply unit is controlled to change a size. Further comprising a time detection unit for detecting the cumulative discharge time in the charging unit,
The power supply unit is formed so as to be able to vary the magnitude of the current supplied to the charging unit,
The control unit controls the current supplied to the charging unit based on the detection result of the time detection unit after the cleaning of the charging unit by the cleaning unit is completed and before an image is formed on the image carrier. The image forming apparatus according to claim 1, wherein the power supply unit is controlled so as to change a size of the image forming apparatus. The cleaning unit further includes a number detection unit that detects the cumulative number of cleaning times,
The power supply unit is formed so as to be able to vary the magnitude of the current supplied to the charging unit,
The control unit controls the current supplied to the charging unit based on the detection result of the number-of-times detection unit after the cleaning unit has finished cleaning the charging unit and before forming an image on the image carrier. The image forming apparatus according to any one of claims 1 to 3, wherein the power supply unit is controlled so as to change the size of the image forming apparatus. The control unit is configured to, when the detection result reaches a reference value, supply the charging unit with a current larger than the current supplied to the charging unit when forming an image on the image carrier. The image forming apparatus according to claim 2, wherein the image forming apparatus controls a unit. An image forming method including a charging step of discharging the charging unit to charge the image carrier and a cleaning step of cleaning the charging unit,
An image forming method comprising: a discharging step of discharging the charging section after the cleaning step and before the charging step. Further comprising a detection step of detecting temperature or / and humidity,
The image forming method according to claim 6, wherein the discharging step includes an adjusting step of adjusting a magnitude of a discharge in the charging unit based on a detection result of the detecting step. Further comprising a time detection step of detecting the accumulated time of performing the charging step,
The image forming method according to claim 6, wherein the discharging step includes an adjusting step of adjusting a magnitude of a discharge in the charging unit based on a detection result of the time detecting step. Further comprising a number detection step of detecting the cumulative number of times the cleaning step has been performed,
The image according to any one of claims 6 to 8, wherein the discharging step includes an adjusting step of adjusting a magnitude of discharging in the charging unit based on a detection result of the number-of-times detecting step. Forming method. The adjusting step is a step in which, when the detection result reaches a reference value, an adjusting step is performed to generate a larger discharge in the charging unit than the discharging in the charging unit in the charging step. The image forming method according to any one of claims 7 to 9, wherein:

Images