JPH05158326A - Image forming device - Google Patents

Abstract

PURPOSE:To properly execute various kinds of corona discharging processing using an AC corona discharger in an image formation, regardless of the linear velocity of a photosensitive body. CONSTITUTION:The AC voltage of a frequency f(Hz) corresponding to the linear velocity v(mm/sec) of the photosensitive body 101, is applied on each AC corona discharger of a pretransfer charger 104 on which a DC biased AC voltage is applied, a separating charger 106, and a precleaning charger 107, which are disposed in the vicinity of the photosensitive body 101 turning at the linear velocity vmm/sec.

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 provided with an AC corona discharger to which a DC biased AC voltage is applied. More specifically, the present invention relates to an AC voltage having a frequency corresponding to the linear velocity of a photoconductor. To an AC corona discharger.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, a plurality of corona dischargers are generally arranged near a photoconductor. This corona discharger is roughly classified into one in which a DC voltage is applied to perform a corona discharge, and one in which a pulsating current voltage in which a DC voltage and an AC voltage are superimposed is applied to perform a corona discharge (AC corona discharge). It can be divided into two.

FIG. 6 is a schematic sectional view of an image forming system of a general image forming apparatus (analog copying machine), which has a drum-shaped photosensitive member 601 rotating at a linear velocity of vmm / sec, and a grid electrode. , Charger 6 for positively charging the surface of photoconductor 601
02, and a developing unit 603 that visualizes the electrostatic latent image formed by performing the exposure process on the charged photoconductor 601 by adhering toner to the electrostatic latent image. The transfer charger 604 that transfers the toner image on the photoconductor 601 onto the recording paper and the charge on the recording paper after the transfer process is completed, the recording paper is transferred to the photoconductor 601.
A separation charger 605 for separating the separation charger 605, a power supply unit 606 for applying a voltage to the separation charger 605, a cleaning unit 607 for removing the toner remaining on the photoconductor 601 after the transfer process, and a photoconductor 601 for which the cleaning process is completed. And a static elimination lamp 608 for erasing the residual charge of

In the above structure, the separation charger 60
Reference numeral 5 is used as an AC corona discharger to which a pulsating current voltage in which a DC voltage and an AC voltage are superimposed is applied from a power supply unit 606. AC corona discharge has a characteristic (hereinafter referred to as AC discharge characteristic) in which a discharge current flows according to the state of the potential so that a negative charge is given to a portion having a high potential and a positive charge is given to a portion having a low potential. Therefore, when AC corona discharge is applied to the recording paper, the charge is removed so that the potential on the recording paper becomes uniform, so that the transferred image is not damaged.
The electrostatic attraction force acting between the photoconductor and the recording paper can be eliminated on average so that the recording paper can be easily separated from the photoconductor.

Further, in the image forming apparatus, in addition to using the AC corona discharger as a separation charger, there are some which are used as a pre-transfer charger, a pre-cleaning charger and the like. The pre-transfer charger is for improving the transferability of the toner image, and the pre-cleaning charger is for improving the cleaning property by increasing the cleaning margin. As shown in FIG. 7 as an example, the photoconductor is formed by forming a carrier generation layer (CGL) 701b on a conductive substrate 701a and a carrier transport layer (CTL) 701c on the CGL 701b.
The CTLs 701c have different mobilities of the positive / negative carriers generated by irradiating the GL701b with light. Therefore, when charged to the same polarity as the carrier with high mobility in the CTL 701c, the photosensitivity is extremely low. Therefore, a pre-charger charger that performs AC corona discharge is installed in order to uniformly and surely charge the photoconductor. There is also an image forming apparatus.

[0006]

However, as an image forming apparatus having a conventional AC corona discharger, for example, an image forming apparatus having a separation charger, recording is performed by setting an applied voltage to a pulsating voltage. Although the separability of the paper from the photoconductor is improved, the separability is reduced depending on the relationship between the linear velocity of the photoconductor and the frequency of the pulsating voltage, and transfer unevenness,
There is a problem that separation jams and the like are likely to occur.

The above problems will be described with reference to specific examples. In the configuration of FIG. 6, the linear velocity v of the photoconductor 601
= 90 mm / sec, DC current I _DC = −2 μA, AC current I _AC = − as AC corona discharge conditions for the separation charger 605.
When a copying process was performed by applying a discharge current of 120 μA and an alternating current (AC) frequency f = 300 Hz (case 1), the separability was good, but the linear velocity v was 90 to 240 mm / sec.
When changing to (Case 2), the charge amount in charging, transfer, and separation, and the light amount in exposure and quenching are set to the linear velocity v.
However, even if the number was increased with the change, no suitable image forming process condition was found. Here, in case 2, the range in which the AC corona discharge condition of the separation charger is adjusted is −2 to −10 μA for direct current I _{DC and} 150 to 30 for alternating current I _AC .
It is 0 μA (f = 300 Hz constant).

In Case 2, separation jams and horizontal stripe-shaped uneven transfer occurred frequently, and cleaning failure also occurred in a copy test of several thousand sheets in succession. Therefore, a pre-transfer charger was installed to improve transferability, and a pre-cleaning charger was installed to improve cleaning performance. As AC corona discharge conditions for these newly installed chargers, direct current I _DC = -20 μA, alternating current I _AC = 150 μA,
A copy test was conducted again by applying a discharge current of AC frequency f = 300 Hz, but no improvement was observed in transfer, separation, and cleaning properties. However, if only the AC frequency f is changed from 300 to 1 KHz from the above conditions,
The transfer, separation and cleaning properties were all good. From these results, it was found that there is a correlation between the AC frequency f and the linear velocity v, and an appropriate image forming process condition cannot be obtained only by increasing the discharge current as the linear velocity v speeds up.

FIG. 8 is an explanatory view showing the charging state of the recording paper when a discharge current having an AC frequency fHz equal to the linear velocity vmm / sec is applied to the separation charger. The potential and solid line are the potential after static elimination by the separation charger. As shown in the figure, it can be seen that the charging potential of the recording paper fluctuates as the alternating voltage makes one cycle while the recording paper moves 1 mm. In this way, when the recording paper after the charge elimination is charged, the transferability of the toner image is good in the part where the charging potential is high, but the separability is poor, and the separation property is good but the transferability is good in the part where the charging potential is valley. Since it is bad, separation jam easily occurs, and the transferred image also has horizontal stripe-shaped unevenness.

The present invention has been made in view of the above, and is an AC for image formation regardless of the linear velocity of the photoconductor.
The purpose is to properly perform various corona discharge treatments using a corona discharger.

[0011]

In order to achieve the above-mentioned object, the present invention comprises a discharging means which is arranged in the vicinity of a photosensitive member which rotates at a linear velocity of vmm / sec and to which an AC voltage is applied. It is an object of the present invention to provide an image forming apparatus in which an AC voltage having a frequency according to the linear velocity v of the photoconductor is applied to the discharging means.

In order to achieve the above object, the present invention is arranged in the vicinity of a photosensitive member which rotates at a linear velocity of vmm / sec,
An image forming apparatus provided with an AC corona discharge unit to which a DC biased AC voltage is applied, in which an AC voltage having a frequency corresponding to a linear velocity vmm / sec of a photoconductor is applied to the AC corona discharge unit. To do.

In the above-mentioned configuration, if the frequency of the AC voltage is fHz and the output waveform of the AC voltage is a rectangular wave, the relationship of f / v> 2.5 is satisfied and the output waveform of the AC voltage is a sine wave. In the case of, it is desirable to satisfy the relationship of f / v> 3.

In order to achieve the above object, the present invention is arranged in the vicinity of a photosensitive member which rotates at a linear velocity of vmm / sec,
An image forming apparatus provided with a separation charger to which a DC biased AC voltage is applied, wherein the frequency fHz of the AC voltage applied to the separation charger satisfies the relationship of f / v> 2. ..

In order to achieve the above object, the present invention is arranged in the vicinity of a photosensitive member which rotates at a linear velocity of vmm / sec,
In an image forming apparatus having a pre-cleaning charger to which a DC biased AC voltage is applied, the frequency fHz of the AC voltage applied to the pre-cleaning charger
Provides an image forming apparatus satisfying the relationship of 2.5 <f / v <10.

In order to achieve the above object, the present invention is arranged in the vicinity of a photosensitive member which rotates at a linear velocity of vmm / sec,
In an image forming apparatus including a pre-quenching charger to which a DC biased AC voltage is applied, the frequency fHz of the AC voltage applied to the pre-quenching charger
Provides an image forming apparatus that satisfies the relationship of 4 <f / v <7.

In order to achieve the above object, the present invention is arranged in the vicinity of a photosensitive member which rotates at a linear velocity of vmm / sec,
In an image forming apparatus including a pre-transfer charger to which a DC biased AC voltage is applied, the frequency fHz of the AC voltage applied to the pre-transfer charger is 3 <f / v <1.
An image forming apparatus that satisfies the relationship of 0 is provided.

[0018]

In the image forming apparatus according to the present invention, an AC voltage having a frequency corresponding to the linear velocity of the photoconductor is applied to the AC corona discharger.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of the experimental apparatus, which has a drum-shaped photosensitive member 101 and a grid electrode,
Charging charger 102 for positively charging the surface of the photoconductor 101
A developing unit 103 that attaches toner to visualize an electrostatic latent image formed by performing an exposure process on the charged photosensitive member 101; and a toner image formed by the developing process. Pre-transfer charger 104 for improving the transfer property of the toner, a power supply unit 104a for applying a voltage to the pre-transfer charger 104, and a transfer charger 105 for transferring the toner image on the photoconductor 101 onto the recording paper conveyed from a conveying system (not shown). And a separation charger 106 that separates the recording paper from the photoconductor 101 by removing the charge of the recording paper after the transfer processing, a power supply unit 106a that applies a voltage to the separation charger 106, and a photosensitive member after the transfer processing. Body 101
The pre-cleaning charger 107 for improving the margin of the cleaning process for removing the toner remaining on the upper side, the power supply unit 107a for applying a voltage to the pre-cleaning charger 107, and the cleaning unit 1 for performing the cleaning process.
08, and a discharge lamp 109 for erasing the electric charges remaining on the photoconductor 101 after the cleaning process is completed.

The operation of the above configuration will be described. The photoconductor 101 rotates at a linear velocity v by a drive system (not shown), and the charging charger 102 positively charges the photoconductor 101. An exposure process is performed subsequent to the photoconductor 101 that has completed the charging process, and the charge on the photoconductor 101 is erased (charged) by the intensity of light to form an electrostatic latent image. The electrostatic latent image is developed by the developing unit 103 to be visualized, and after development processing, pre-transfer charge elimination processing by AC corona discharge of the pre-transfer charger 104 is performed, and a toner image is formed on the recording paper conveyed from the conveyance system. It is transferred by the action of the transfer charger 104. The separation charger 105 separates the recording paper on which the transfer process is completed from the photoconductor 101. AC corona discharge is performed by the pre-cleaning charger 107 on the photoconductor 101 after the transfer process to improve the charge removal property and the cleaning property.
The toner remaining on the first toner is removed. After the cleaning process is completed, the photoconductor 101 is irradiated with the light of the static elimination lamp 109 to erase the residual charges, and the one step is completed.

Next, an experiment conducted by using the experimental apparatus having the above-mentioned structure and operation will be described. In this experiment, the linear velocity v of the photoconductor 101 was kept constant at 120 mm / sec, and the AC frequency f was changed to examine the linear velocity dependence. As the AC voltage, experiments were performed using a rectangular wave and a sine wave to investigate the dependence on the output waveform. Table 1 shows a comprehensive evaluation of the separability, transferability, and cleaning property of the experimental results.

[0022]

[Table 1]

From the experimental results shown in Table 1, f /
v is 2.5 cycle / mm or more, f / v is 3 cycle / for sine wave
It can be seen that the value of mm or more is a proper condition of the AC frequency f with respect to the linear velocity v. When the AC frequency f becomes high, various kinds of processing can be properly performed because the peaks (or valleys) of the voltage applied while the surface of the photoconductor 101 moves by a unit distance increase, that is, the peaks and peaks of the voltage. Since the interval between the two becomes narrower, the charge removal unevenness (in this experiment, the pre-transfer charger 1
04, the separation charger 106, and the pre-cleaning charger 107 are performing static elimination),
In addition, it is considered that the effect of the AC corona discharge characteristic becomes large. The reason that the appropriate conditions differ slightly between the rectangular wave and the sine wave is considered to be due to the difference in effective value.

FIG. 2A is a schematic sectional view of an image forming system of the digital copying machine according to the first embodiment, in which a drum-shaped photosensitive member 201 using OPC (organic optical semiconductor) and a grid electrode are formed. A charging charger 102 that has a negative charge on the surface of the photoconductor 201, a laser writing unit 202 that performs an exposure process with a laser beam on the photoconductor 201 that has been charged,
A developing unit 203 for reversing and developing the electrostatic latent image formed by the exposure process, a transfer charger 105 for transferring the toner image on the photoconductor 201 onto a recording sheet conveyed from a conveying system (not shown), and a transfer charger after completion of the transfer process. A separation charger 106 that separates the recording paper from the photoconductor 201 by removing the electric charge of the recording paper, and a cleaning for improving the efficiency of the cleaning process that removes the toner remaining on the photoconductor 201 after the transfer process is completed. It comprises a front charger 107, a cleaning unit 108 for performing a cleaning process, and a discharge lamp 109 for erasing the electric charge remaining on the photoconductor 201 after the cleaning process.

In the above configuration, the separation charger 10
6 and the pre-cleaning charger 107 were subjected to a copy test by applying a DC biased rectangular wave AC voltage as shown in FIG. Specific conditions for the copy test are: linear velocity v = 150 mm / sec, AC corona discharge conditions for the separation charger 106 are DC current I _DC = −5 μA, AC current I _AC = 180 μA, AC frequency f = 500 Hz, charger before cleaning. The AC corona discharge condition of 107 is DC current I _DC = -18 μA, AC current I _AC = 120 μA,
AC frequency f = 500 Hz.

The f / v value in this copy test is 3.
It was 3 (= 500/150) cycle / mm, and the separability, transferability, and cleaning property were good, and the charge was uniformly discharged. As a result, it is found that it is effective to apply the AC frequency f corresponding to the linear velocity v to the various AC corona dischargers in order to properly perform the various processes.

FIG. 3A is a schematic sectional view of an image forming system of an analog copying machine according to the second embodiment, showing a drum-shaped photosensitive member 301 having a Se-based photosensitive layer and a surface of the photosensitive member 301. A charger 302 that is positively charged, a developing unit 303 that develops an electrostatic latent image formed by performing an exposure process on the photoconductor 301 that has been subjected to a charging process, and a transfer of a toner image formed by the developing process. By a pre-transfer charger 104 that improves the transferability, a transfer charger 105 that transfers the toner image on the photoconductor 301 onto the recording paper transported from a transport system (not shown), and the charge on the recording paper after the transfer process is completed. , A separation charger 106 for separating the recording sheet from the photoconductor 301, and a cleaning charger for improving the efficiency of the cleaning process for removing the toner remaining on the photoconductor 301 after the transfer process. And cleaning before the charger 107,
The cleaning unit 108 includes a cleaning unit 108 that performs a cleaning process, and a discharge lamp 109 that erases charges remaining on the photoconductor 301 after the cleaning process.

In the above configuration, the pre-transfer charger 1
04, the separation charger 106, and the pre-cleaning charger 107 were subjected to a copy test by applying an AC voltage having a sine wave as shown in FIG. The specific copy test condition is a linear velocity v = 280 mm / sec, and the AC corona discharge condition of the pre-transfer charger 104 is a direct current I _DC = −2.
2 μA, AC current I _AC = 150 μA, AC frequency f = 1
KHz, AC corona discharge condition of the separation charger 106 is DC current I _DC = -10 μA, AC current I _AC = 220 μ
A, AC frequency f = 1 KHz, AC corona discharge condition of the pre-cleaning charger 107 is DC current I _DC = −20
μA, AC current I _AC = 150 μA, AC frequency f = 1K
Hz.

The f / v value in this copy test is
It was 3.5 cycle / mm, and the separability, transferability, and cleaning property were good, and no problems occurred even after performing 10,000 copy tests. From this, it can be seen that setting the AC frequency f according to the linear velocity v is effective for properly performing various processes.

Next, the linear velocity dependence of the separability, transferability and cleaning property was evaluated in more detail using the experimental apparatus shown in FIG. The results of this experiment are shown in Table 2. In this experiment, the linear velocity v is constant at 120 mm / sec and the AC waveform is a rectangular wave.

[0031]

[Table 2]

From the results shown in Table 2, the separability is 2 for f / v.
It can be seen that proper conditions are cycle / mm or more, transferability f / v is 3 cycle / mm or more, and cleaning ability is f / v is 2.5 cycle / mm or more. AC frequency f that satisfies this appropriate condition
Although various processes such as separation and cleaning can be satisfactorily performed when the AC voltage is set to, the problem is that generally, when the AC frequency f becomes high, the amount of ozone generated increases. Therefore, as a result of repeating the experiment using the experimental apparatus shown in FIG. 1 and the digital copying machine shown in FIGS. 4 and 5 which will be described later, the appropriate conditions for each charger are as follows. • Pre-transfer charger; 3 <f / v <10 • Separation charger; f / v> 2 • Pre-cleaning charger; 2.5 <f / v <
10 · Charge before quenching; 4 <f / v <7 Here, the reason that the separation charger has no upper limit on the f / v value is that the recording paper is interposed between the separation charger and the photoconductor.

FIG. 4 is a schematic sectional view of the image forming system of the digital copying machine according to the third embodiment, in which the drum-shaped photoconductor 20 is used.
1, a charging charger 401 that negatively charges the surface of the photoconductor 201, a laser writing unit 202 that performs an exposure process on the charged photoconductor 201 with a laser beam, and an electrostatic latent image formed by the exposure process. Developing unit 40 for reversing and developing an image
2, a transfer charger 105 that transfers the toner image on the photoconductor 201 onto the recording paper 406 conveyed from a conveyance system (not shown), and the recording paper 406 after the transfer processing is completed by removing the electric charge. The separation charger 106 that separates the recording paper 406 from the photoconductor 201 and the recording paper 406 to the photoconductor 20.
1, a separation claw 403 for surely separating it from No. 1, a pre-cleaning charger 107 for improving the margin of the cleaning process for removing the toner remaining on the photoconductor 201 after the completion of the transfer process, and a cleaning for performing the cleaning process. The unit 404 and a static elimination lamp 405 that erases the electric charge remaining on the photoconductor 201 after the cleaning process is completed. The cleaning unit 404 is
This is a brush cleaning method having a cleaning brush 404a, and a roller 404b to which a positive voltage is applied from a DC power source 404c is in contact with the cleaning brush 404a.

In the above structure, the linear velocity v = 150 mm / s
ec, AC corona discharge conditions of the separation charger 106 are DC current I _DC = -5 μA, AC current I _AC = 180 μA, AC
Frequency f = 500 Hz, pre-cleaning charger 10
The AC corona discharge condition of No. 7 is direct current I _DC = -18 μA,
AC current I _AC = 120 μA, AC frequency f = 500 Hz
Then, a voltage of 300 V was applied to the cleaning brush 404a to perform a copy test.

The f / v value in this copy test is 3.
It was 3 cycle / mm, and the separation, transferability, and cleaning properties were good. In addition, the charge was removed uniformly, and a clear image could be obtained.

FIG. 5 is a schematic sectional view of the image forming system of the digital copying machine according to the fourth embodiment. From the configuration shown in FIG.
The cleaning unit 404 of the brush cleaning system is changed to the cleaning unit 501 of the blade cleaning system, and the pre-quenching charger 502 is provided instead of the pre-cleaning charger 107. The pre-quenching charger 502 receives AC biased DC voltage from the power supply unit 502a to perform AC corona discharge.

In the above structure, the linear velocity v = 150 mm / s
ec, AC corona discharge conditions of the separation charger 106 are DC current I _DC = −3 μA, AC current I _AC = 150 μA, AC
Frequency f = 500 Hz, charger 10 before quenching
The AC corona discharge condition of No. 7 is direct current I _DC = −15 μA,
AC current I _AC = 120 μA, AC frequency f = 500 Hz
As a copy test.

The f / v value in this copy test is 3.
It was 3 cycles / mm, and the separability, transferability, and static elimination were good, and it was confirmed that various treatments were performed properly.

In this embodiment, the proper condition of the AC frequency f of each charger at the linear velocity v is determined by using a rectangular wave as the AC waveform. Therefore, this appropriate condition has a slight difference depending on the AC waveform. Moreover, since the amount of ozone generated varies depending on the peak-to-peak voltage of the AC voltage and the environment (particularly humidity), the appropriate conditions also vary to some extent depending on the peak-to-peak voltage and the environment.

Further, in the image forming apparatus, for example,
There is one that can transfer a plurality of toner images onto one recording sheet by providing a transfer drum. In this transfer drum, generally, when the image formation is completed, the charge charged by the transfer process is removed by using an AC corona discharger. In the present invention, the AC corona discharger is arranged near the transfer drum. It can also be applied to an image forming apparatus.

[0041]

As described above, according to the present invention, since an AC voltage having a frequency corresponding to the linear velocity of the photoconductor is applied to the AC corona discharger, the AC corona discharge in image formation is performed regardless of the linear velocity of the photoconductor. Various corona discharge treatments using electric appliances can be properly performed.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an experimental device.

FIG. 2 is a schematic sectional view showing an image forming system of the digital copying machine according to the first embodiment (a), and an explanatory view showing a waveform of a voltage applied to each AC corona discharger (b).

FIG. 3 is a schematic sectional view (a) showing an image forming system of an analog copying machine according to a second embodiment, and an explanatory view (b) showing a waveform of a voltage applied to each AC corona discharger.

FIG. 4 is a schematic sectional view showing an image forming system of a digital copying machine according to a third embodiment.

FIG. 5 is a schematic sectional view showing an image forming system of a digital copying machine according to a fourth embodiment.

FIG. 6 is a schematic sectional view showing an image forming system of a general image forming apparatus.

FIG. 7 is an explanatory diagram showing a photosensitivity characteristic of a photoconductor.

FIG. 8 is an explanatory diagram showing a charged state of the recording paper when an AC voltage having a frequency equal to the linear velocity is applied to the separation charger.

[Explanation of symbols]

101 201 301 photoconductor 104 pre-transfer charger 104a 106a 107a 502a power supply unit 106 separation charger 107 pre-cleaning charger 502 pre-quenching charger

Claims (7)

[Claims] 1. An image forming apparatus provided with a discharge means arranged near a photoconductor that rotates at a linear velocity vmm / sec and to which an AC voltage is applied, wherein the discharge means has a linear velocity v of the photoconductor.
An image forming apparatus, wherein an AC voltage having a frequency according to the above is applied. 2. An A disposed to the vicinity of a photosensitive member which rotates at a linear velocity of vmm / sec and to which an AC voltage with a DC bias is applied.
An image forming apparatus having a C corona discharge means, wherein an AC voltage having a frequency corresponding to a linear velocity vmm / sec of the photoconductor is applied to the AC corona discharge means. 3. When the frequency of the AC voltage is fHz, the relationship of f / v> 2.5 is satisfied when the output waveform of the AC voltage is a rectangular wave, and f / v> 2.5 when the output waveform of the AC voltage is a sine wave.
3. The relationship of v> 3 is satisfied, and the relationship is 1 or 2.
Image forming device. 4. An image forming apparatus equipped with a separation charger, which is arranged in the vicinity of a photoconductor rotating at a linear velocity of vmm / sec and to which a DC biased AC voltage is applied, and an AC applied to the separation charger. The frequency fHz of the voltage is f /
An image forming apparatus characterized by satisfying a relationship of v> 2. 5. An image forming apparatus comprising a pre-cleaning charger, which is arranged in the vicinity of a photoconductor rotating at a linear velocity of vmm / sec and to which a DC biased AC voltage is applied, to the pre-cleaning charger. An image forming apparatus characterized in that a frequency fHz of an alternating voltage to be satisfied satisfies a relationship of 2.5 <f / v <10. 6. An image forming apparatus provided with a pre-quenching charger, which is disposed in the vicinity of a photoconductor rotating at a linear velocity of vmm / sec, and to which a DC biased AC voltage is applied. An image forming apparatus characterized in that a frequency fHz of an AC voltage applied to the device satisfies a relationship of 4 <f / v <7. 7. An image forming apparatus comprising a pre-transfer charger, which is arranged near a photosensitive member rotating at a linear velocity of vmm / sec and to which a DC biased AC voltage is applied, to the pre-transfer charger. The frequency fHz of the alternating voltage
An image forming apparatus characterized by satisfying a relationship of 3 <f / v <10.