JP2001201918A - Power source unit, method of electrification, electrifying device, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power source unit, a method of electrification, an electri fying device, and an image forming device wherein a current value control method of a constant current method is used which is advantageous in cost and can accurately control the current. SOLUTION: The power source 12 is controlled by the current wave form caught by a means (integration circuit) 13 for measuring the integration value of the current wave, measuring the integral value of the current wave by an integration circuit, and controlling a power source so as to make the same constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power supply device, a charging method, a charging device, and an image forming apparatus.

[0002]

2. Description of the Related Art For convenience, a description will be given of an example of a charging process of a photosensitive member as an image bearing member in an electrophotographic apparatus.

As is well known, an electrophotographic apparatus includes a step of uniformly charging a surface of a photoreceptor to a predetermined potential. As the charging means, a means utilizing corona discharge, such as a non-contact type corona discharger, and a contact charging means are often used.

The contact charging means is a method of charging by bringing a conductive charging member to which a voltage is applied from the outside into contact with an object to be charged such as a photoreceptor, and generates a discharge product or ozone more than a corona discharger. It is possible to suppress as much as possible.

A roller charging system using a conductive elastic roller as a charging member is preferably used from the viewpoint of charging stability. In order to obtain a desired potential Vd on the surface of the photoreceptor by the roller charging method, the charging roller needs to have Vd + Vth.
A DC voltage is applied (a discharge starting voltage (charging start voltage) to the member to be charged when a DC voltage is applied to the charging member).

As disclosed in JP-A-63-149668, a DC voltage corresponding to a desired potential Vd is applied with a peak-to-peak voltage of twice or more Vth, as disclosed in JP-A-63-149668. The "AC charging method" is used in which a voltage (alternating voltage, pulsating voltage, and oscillating voltage; a voltage whose voltage value changes periodically with time) superimposed on an alternating voltage component (AC voltage component) is applied to the contact charging member. Can be

However, the charging member may be affected by the environment, especially humidity, and the resistance of the charging member increases in a low humidity environment due to an increase in resistance and a decrease in the dielectric constant. On the contrary, the resistance decreases in a high humidity environment. In addition, the impedance of the charging member decreases due to the increase in the dielectric constant.

As a result, in a low humidity environment, the AC component of the voltage applied by the power supply is attenuated by the impedance of the charging member, and the discharge starting voltage Vth described above is applied between the charging member and the member to be charged. In some cases, an oscillating electric field having a peak-to-peak voltage that is twice or more of the above is not formed, and spot-like charging failure, that is, uneven charging may be performed.
In anticipation of the decay of the AC component due to the impedance of the charging member in a low humidity environment, an oscillating electric field having a peak-to-peak voltage of at least twice the discharge start voltage between the charging member and the member to be charged even under low humidity As formed, it is possible to apply an alternating voltage having a high peak-to-peak voltage value to the charging member. However, in a high-humidity environment in which the impedance of the charging member decreases, a high voltage is directly applied to the member to be charged without the AC component being attenuated by the charging member. In a high humidity environment where characteristics are deteriorated, there is a disadvantage against leakage of the member to be charged or the charging member.

Therefore, there is a constant current method for controlling the current to a predetermined current value as disclosed in Japanese Patent Application Laid-Open No. 06-093150. The constant current method is a very effective means for the above point, and is currently used in many charging means.

As a method for controlling the current value in the constant current method, there is a control method using a peak hold circuit. The control method using the peak hold circuit is a circuit that half-wave rectifies the voltage across a certain resistor in the current detection circuit and holds the peak value. Since the peak value is usually proportional to the AC waveform current flowing through the charging member, the current value can be controlled to be constant.

[0011]

The alternating current flowing through the charging member includes the above-described current flowing through the capacitance component and the resistance component depending on the dielectric constant, and the discharge current between the charging member and the member to be charged. ing. When the waveform of the AC voltage applied to the charging member is a single sine wave, the waveform of the AC current flowing through the charging member is shifted in phase from the voltage waveform of the applied voltage because the waveform of the current flowing through the capacitance component is out of phase. And a resistance component and a discharge current. Normally, the composite wave, that is, the current waveform has a shape almost similar to the applied voltage waveform, and when the current control range is limited, the current waveform can be predicted. The current method can accurately control the current value.

However, when a cleaning device (cleaner) or the like is used in combination, there is a problem that photoreceptor drum deterioration such as abrasion of the photoreceptor drum is accelerated. In the constant current method using the peak hold circuit, there is a problem that a stable discharge current amount cannot be obtained depending on the conditions of the photosensitive drum and the like. Also in the above-mentioned contact type roller charging method, it is possible to suppress the discharge product as much as possible compared to the means using corona discharge, but it is possible to minimize the discharge product, especially cleaning for collecting residual toner on the photoreceptor. In a so-called cleaner-less system, in which there is no device and the residual toner is collected by a developing device, the surface of the photoreceptor has low resistance due to the adhesion of discharge products, and the resolution of the latent image is reduced. Since it cannot be expected, there is an adverse effect on discharge products such as image blur and image deletion. Therefore, there are cases where it is desired to control the current value more accurately and to minimize the generation of discharge products. As described above, the current waveform
Since it appears as a composite wave of the capacitance component, the resistance component, and the discharge current, it is very difficult to detect a minute change in the current waveform due to the increase and decrease of the discharge current when a peak hold circuit is used.

Further, the one using the effective value calculation circuit is disadvantageous in that it is expensive.

The present invention solves the above problems,
An object of the present invention is to provide a power supply device, a charging method, a charging device, and an image forming apparatus using a current value control method of a constant current method that can accurately perform current control and is cost effective. It is in.

[0015]

According to the present invention, there is provided a power supply device, a charging method, a charging device, and an image forming apparatus having the following constitutions.

(1) A power supply which has a power supply for generating a voltage and means for measuring an integrated value of a current waveform, and outputs a voltage so that the integrated value of the current waveform per unit time is constant. apparatus.

(2) The power supply device according to (1), which has a voltage of a DC component and a voltage of an AC component.

(3) In a charging method for applying a voltage to the charging means brought into contact with the object to be charged to charge the object to be charged, the voltage applied to the charging means may be such that the integral value of the current waveform per unit time is A charging method characterized in that the charging is controlled to be constant.

(4) The charging method according to (3), wherein the voltage applied to the charging means is a voltage having a DC component and an AC component.

(5) The charging method according to (4), wherein the absolute value of the amplitude of the current waveform of the AC component is integrated.

(6) The charging method according to any one of (1) to (5), wherein the charging means has a roller shape.

(7) In a charging apparatus having a charging means in contact with an object to be charged and a power supply for outputting a voltage to be applied to the charging means, the power supply includes a power supply for generating a voltage and an integration of a current waveform. A charging device comprising means for measuring a value, and outputting a voltage to be applied to the charging means so that an integral value of a current waveform per unit time is constant.

(8) The charging device according to (7), wherein the voltage applied to the charging means is a voltage having a DC component and an AC component.

(9) The charging device according to (8), wherein the absolute value of the amplitude of the AC component current waveform is integrated.

(10) The charging device according to any one of (7) to (9), wherein the charging means has a roller shape.

(11) In an image forming apparatus for forming an image by applying an image forming process including a step of charging the image carrier to the image carrier, the charging device for charging the image carrier is an image carrier. A charging unit that contacts the body, and a power supply device that outputs a voltage applied to the charging unit, the power supply device includes:
An image, comprising: a power supply for generating a voltage; and means for measuring an integrated value of a current waveform, and outputting a voltage to be applied to the charging means so that the integrated value of the current waveform per unit time is constant. Forming equipment.

(12) The image forming apparatus according to (11), wherein the voltage applied to the charging means is a voltage having a DC component and an AC component.

(13) The image forming apparatus according to (12), wherein the absolute value of the amplitude of the AC component current waveform is integrated.

(14) The image forming apparatus according to any one of (11) to (13), wherein the charging means has a roller shape.

<Operation> In the present invention, the current waveform is captured by using a means (integrating circuit) for measuring the integrated value of the current waveform. By obtaining the integrated value of the current waveform using the integration circuit, it is possible to catch a minute change in the current waveform due to the increase or decrease of the discharge current. That is, by measuring the integrated value of the current waveform by the integrating circuit and controlling the power supply so that the integrated value becomes constant, the current control can be performed more accurately.

[0031]

FIG. 1 is a schematic structural diagram of an example of an image forming apparatus according to the present invention. The image forming apparatus of this embodiment is a laser beam printer using a transfer type electrophotographic process, a contact charging type, a reversal developing type, a cleaner-less type, and a maximum sheet passing size of A3 size.

(1) Overall Schematic Configuration of Printer a) Image Carrier 1 A rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) as an image carrier. The photosensitive drum 1 is a negatively chargeable organic photoconductor (OPC) having an outer diameter of 50 mm.
mm, and is driven to rotate counterclockwise as indicated by an arrow at a process speed (peripheral speed) of 100 mm / sec around the center support shaft.

As shown in the schematic diagram of the layer structure in FIG. 2, the photosensitive drum 1 has an undercoating on the surface of an aluminum cylinder (conductive drum base) 1a for suppressing light interference and improving the adhesiveness of the upper layer. It has a configuration in which three layers of a layer 1b, a photocharge generation layer 1c, and a charge transport layer 1d are sequentially applied from the bottom.

B) The charging means 2 is a contact charging device (contact charging device) as a charging device for uniformly charging the peripheral surface of the photosensitive drum 1, and in this example, a charging roller (roller charging device). .

The charging roller 2 rotatably holds both ends of the cored bar 2a by bearing members (not shown), and urges the photosensitive drum 1 in the direction of the photosensitive drum by a pressing spring 2e. Is pressed against the surface of the photosensitive drum with a predetermined pressing force, and rotates following the rotation of the photosensitive drum 1. The pressure contact portion between the photosensitive drum 1 and the charging roller 2 is a charging portion (charging nip portion) a.

When a charging bias voltage under predetermined conditions is applied from a power source S1 to the core metal 2a of the charging roller 2, the peripheral surface of the rotating photosensitive drum 1 is uniformly contact-charged to a negative polarity in this embodiment. It is processed.

The configuration, charging conditions, charging control method and the like of the charging roller 2 will be described in detail in (2).

C) Information writing means 3 is an exposure device as information writing means for forming an electrostatic latent image on the surface of the charged photosensitive drum 1, and is a laser beam scanner in this embodiment. A laser beam modulated in accordance with an image signal sent from the host device such as an image reading device (not shown) to the printer side is output to scan the uniformly charged surface of the rotary photosensitive drum 1 at the exposure position b. Exposure L is performed. Due to the laser scanning exposure L, the potential at the portion irradiated with the laser beam on the surface of the photosensitive drum 1 is reduced, so that an electrostatic latent image corresponding to the scanned and exposed image information is sequentially formed on the surface of the rotating photosensitive drum 1 Will be done.

D) Developing means 4 is a developing device (developing device) as developing means for supplying a developer (toner) to the electrostatic latent image on the photosensitive drum 1 and visualizing the electrostatic latent image. Reference numeral denotes a reversal developing device of a two-component magnetic brush developing system. The electrostatic latent images formed on the surface of the photoreceptor drum 1 are successively formed as toner images by the developing device 4 in this embodiment. (Negative toner)
The reversal development is carried out.

Reference numeral 4a denotes a developing container, and 4b denotes a non-magnetic developing sleeve. The developing sleeve 4b is rotatably disposed in the developing container 4a by exposing a part of its outer peripheral surface to the outside. Reference numeral 4c denotes a non-rotating fixed magnet roller inserted in the developing sleeve 4b, 4d denotes a developer coating blade, 4e denotes a two-component developer contained in the developing container 4a, and 4f denotes a bottom side in the developing container 4a. The provided developer agitating member, 4g, is a toner hopper, which stores toner for replenishment.

The two-component developer 4e in the developing container 4a is a mixture of a toner and a magnetic carrier.
Is stirred. In this example, the magnetic carrier has a resistance of about 10 ¹³ Ωcm and a particle size of about 40 μm. The toner is triboelectrically charged to a negative polarity by rubbing with the magnetic carrier.

The developing sleeve 4b is opposed to the photosensitive drum 1 while keeping the closest distance (referred to as S-Dgap) to the photosensitive drum 1 at 350 μm. The facing portion between the photosensitive drum 1 and the developing sleeve 4b is a developing portion c. The developing sleeve 4b is rotationally driven in the developing section c in a direction opposite to the traveling direction of the photosensitive drum 1. A part of the two-component developer 4e in the developing container 4a is attracted and held as a magnetic brush layer on the outer peripheral surface of the developing sleeve 4b by the magnetic force of the magnet roller 4c in the sleeve, and is rotationally conveyed with the rotation of the sleeve. The developer is coated into a predetermined thin layer by the developer coating blade 4d, and is brought into contact with the surface of the photosensitive drum 1 in the developing section c to rub the surface of the photosensitive drum appropriately. Power supply S2 is applied to developing sleeve 4b.
, A predetermined developing bias is applied.

Thus, the surface of the rotating developing sleeve 4b is coated as a thin layer, and the amount of toner in the developer conveyed to the developing section c is applied to the surface of the photosensitive drum 1 by the electric field generated by the developing bias. , The electrostatic latent image is developed as a toner image. In the case of this example, the toner adheres to the exposed light portion on the surface of the photosensitive drum 1 and the electrostatic latent image is reversely developed.

The developer thin layer on the developing sleeve 4b that has passed the developing section c is returned to the developer reservoir in the developing container 4a with the subsequent rotation of the developing sleeve.

In order to maintain the toner concentration of the two-component developer 4e in the developing container 4a within a predetermined substantially constant range, the toner concentration of the two-component developer 4e in the developing container 4a is not The toner is detected by the density sensor, and the toner hopper 4g is driven and controlled in accordance with the detection information, and the toner in the toner hopper is supplied to the two-component developer 4e in the developing container 4a. The toner supplied to the two-component developer 4e is stirred by the stirring member 4f.

E) Transfer Means / Fixing Means 5 is a transfer device, and in this embodiment, a transfer roller. The transfer roller 5 is pressed against the photosensitive drum 1 with a predetermined pressing force, and the pressing nip portion is a transfer portion d. A transfer material (transfer member, recording material) P is fed to the transfer portion d from a paper feed mechanism (not shown) at a predetermined control timing.

The transfer material P fed to the transfer section d is conveyed while being sandwiched between the rotating photosensitive drum 1 and the transfer roller 5, during which the transfer roller 5 has the normal charging polarity of the toner from the power source S 3. By applying a positive transfer bias having a polarity opposite to the negative polarity, the toner image on the photosensitive drum 1 surface side is sequentially electrostatically transferred onto the surface of the transfer material P which is nipping and transferring the transfer portion d. Will be done.

The transfer material P having received the transfer of the toner image through the transfer portion d is sequentially separated from the surface of the rotating photosensitive drum 1 and is conveyed to a fixing device 6 (for example, a heat roller fixing device) to fix the toner image. Image processing (print,
Output).

F) Cleanerless The printer of this embodiment is cleanerless, and is provided with a dedicated cleaning device for removing a small amount of transfer residual toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image onto the transfer material P. Absent. The untransferred toner on the surface of the photosensitive drum 1 after the transfer is carried to the developing unit c through the charging unit a and the exposing unit b as the photosensitive drum 1 continues to rotate, and is simultaneously cleaned by the developing device 4 (development simultaneous cleaning). Collected) (cleanerless system).

Since the untransferred toner on the surface of the photosensitive drum 1 passes through the exposure section b, the exposure process is performed on the untransferred toner. However, since the amount of the untransferred toner is small, there is no significant effect.

Reference numeral 7 denotes a toner charging control unit, which is a transfer unit d.
It is disposed downstream of the photosensitive drum rotation direction and upstream of the charging unit a in the rotation direction of the photosensitive drum. The toner charging control means 7 is a brush-shaped member having a suitable conductivity, and is disposed with the brush portion in contact with the surface of the photosensitive drum 1. A negative voltage is applied from the power supply S 4. I have. “e” denotes a contact portion between the brush portion and the surface of the photosensitive drum 1. The transfer residual toner on the photosensitive drum 1 that passes through the toner charge control means 7 has its charge polarity adjusted to the negative polarity, which is the normal polarity. That is, the transfer residual toner on the surface of the photosensitive drum 1 after the transfer process is affected by the negative toner of the image portion, the positive toner of the non-image portion, and the positive voltage of the transfer, and the polarity is reversed to the positive polarity. Includes depleted toner. Such transfer residual toner is uniformly charged to the negative polarity by the toner charging control means 7 and passes through the charging section a without adhering to the charging roller 2 and is carried to the developing section c. In the developing step, the transfer residual toner on the photosensitive drum 1 that should not be developed with the toner is collected by the developing device 4 due to the electric field.

(2) Detailed Description of Charging Means The longitudinal length of the charging roller 2 as a contact charging member is 320
2 and a three-layer configuration in which a lower layer 2b, an intermediate layer 2c, and a surface layer 2d are sequentially stacked from the bottom around a cored bar (supporting member) 2a as shown in the layer configuration model diagram of FIG. Lower layer 2
b is a foamed sponge layer for reducing charging noise, the intermediate layer 2c is a conductive layer for obtaining uniform resistance as a whole of the charging roller, and the surface layer 2d has defects such as pinholes on the photosensitive drum 1. This is a protective layer provided to prevent the occurrence of a leak even if it is present.

More specifically, the specifications of the charging roller 2 of this embodiment are as follows.

Core 2a: Stainless steel round bar with a diameter of 6 mm Lower layer 2b: Carbon-dispersed foamed EPDM, specific gravity 0.5
g / cm ³ , volume resistance 10 ² to 10 ⁹ Ωcm, layer thickness 3.0 mm, length 320 mm middle layer 2c; NBR rubber dispersed with carbon, volume resistance 10 ² to 10 ⁵ Ωcm, layer thickness 700 μm, surface layer 2d A dispersion of tin oxide and carbon in a resinous resin of a fluorine compound, a volume resistivity of 10 ⁷ to 10 ¹⁰ Ωcm, a surface roughness (average surface roughness Ra) of 1.5 μm, a layer thickness of 10 μm, and a frequency from a power source S1 to a DC voltage A predetermined oscillating voltage (bias voltage Vd
By applying (c + Vac) to the charging roller 2 via the metal core 2a, the peripheral surface of the rotating photosensitive drum 1 is charged to a predetermined potential.

Next, a control method in the charging step will be described. FIG. 3 is a block diagram of a power supply circuit applied to the charging roller 2. Reference numeral 11 denotes a DC power supply, and 12 denotes an AC power supply. A vibration voltage Vdc + Vac in which a DC voltage Vdc output from the DC power supply 11 and an AC voltage Vac output from the AC power supply 12 are superimposed is applied to the charging roller 2.
Reference numeral 13 denotes an integrating circuit as a means for measuring an integrated value of a current waveform flowing through the charging roller 2. Reference numeral 14 denotes a CPU as a control circuit.

In this power supply circuit, a sine wave AC voltage Vac having a frequency of 1000 Hz is generated in the AC power supply 11,
The AC voltage component at that time, that is, the peak-to-peak voltage, is feedback-controlled so that the integration value obtained by converting the AC current waveform by the integration circuit 13 is constant. That is,
A voltage to be applied to the charging roller 2 is output so that the integral value of the current waveform per unit time is constant.

In the present embodiment, the integral calculation is performed by the integrating circuit 13, and the integrated value is output as a DC voltage, and is output to the CPU 14 through AD conversion.

Here, the integration method will be described. FIG.
If the AC current waveform is a sine wave as shown in FIG. Therefore, as shown in FIG. 4B, the absolute value of the amplitude value of the current waveform is integrated and calculated by using the absolute value circuit once for the current waveform. Further, a waveform of a half cycle may be integrated and calculated.

Here, the current waveform of the current flowing to the charging roller 2 in the configuration of the present embodiment will be described.

As disclosed in Japanese Patent Application Laid-Open No. 63-149668, when a DC voltage is applied to the charging roller, it is necessary to obtain a desired potential Vd on the photosensitive member surface by Vd + Vth.
(Discharge start voltage) is required, and in the case of a voltage on which an AC voltage component is superimposed, a DC voltage corresponding to a desired potential Vd is 2
It is known that a peak-to-peak voltage of twice or more Vth is required.

In the structure of this embodiment, Vth is 100
0V. Therefore, an AC voltage which is a sine wave having a frequency of 1000 Hz and a peak-to-peak voltage of 700 V as shown in FIG.
A bias on which a DC voltage of 0 V is superimposed is applied to the charging roller 2. The waveform of the current flowing to the charging roller 2 at that time is shown in FIG. It can be seen that the phase of the current waveform is shifted compared to the phase of the voltage waveform.

On the other hand, FIG. 6A shows a similar current waveform when the peak-to-peak voltage is set to 1100 V, which is a peak-to-peak voltage slightly exceeding Vth. A current waveform corresponding to the discharge current can be confirmed in the current waveform at a phase near the peak value of the voltage waveform. Further, the peak-to-peak voltage was increased to 18
A similar current waveform when the voltage is set to 00 V is shown in FIG. It can be seen that the current waveform for the discharge current is further increased.

Therefore, in the case where the peak value of the current waveform is controlled to be constant by the peak hold circuit, the current waveform of the discharge current at the peak-to-peak voltage near the discharge starting voltage as described above cannot be captured. Understand.

In a so-called cleaner-less system in which there is no cleaning device for collecting the residual toner on the photosensitive drum 1 as in the present embodiment, and the residual toner is collected by the developing device 4, etc. The adhesion lowers the surface of the photoconductor drum, lowers the resolving power of the latent image, and makes it impossible to obtain the renewal effect of the cleaning device.

Therefore, it is desired to control the current value more accurately and to minimize the generation of discharge products. Since the current waveform appears as described above, it is very difficult to detect a minute change in the current waveform due to the increase or decrease of the discharge current when the peak hold circuit is used.

As described above, by controlling the voltage applied to the charging roller so that the integrated value of the current waveform per unit time is constant by the integrating circuit used in the present embodiment, the current value can be more accurately obtained. It can be grasped and controlled.

In this embodiment, the description has been given of the image forming apparatus of the cleanerless system. However, the image forming apparatus using the cleaning device 8 as shown in FIG.
Since the electric capacity also changes due to the deterioration of the photosensitive drum due to the scraping of the photosensitive drum 1 or the like, the current flowing to the charging roller 2 also changes. That is, a change occurs in the current waveform, and in the constant current method using the peak hold circuit, a stable discharge current amount cannot be obtained depending on the conditions of the photoreceptor drum and the like. Therefore, by controlling the integration value of the current waveform to be constant by the integration circuit, the current value can be improved by grasping and controlling the current value more accurately.

(3) Others 1) The charging member does not necessarily have to be in contact with the surface of the member to be charged, and even between the charging member and the member to be charged, even the dischargeable region determined by the gap voltage and the corrected Paschen curve is reliable. If it is ensured that they are close to each other without contact (proximity charging), for example, there may be a gap (gap) of several tens μm,
In the present invention, this case is also included in the category of contact charging.

2) The image bearing member has a surface resistance of 10 ⁹ to 10 ^14.
It may be of a direct injection charging type provided with a charge injection layer of Ω · cm. Even when the charge injection layer is not used, the same effect can be obtained, for example, when the charge transport layer is in the above-described resistance range. An amorphous silicon photoreceptor whose surface layer has a volume resistance of about 10 ¹³ Ω · cm may be used.

3) In addition to the charging roller, a flexible contact charging member having a shape and material such as a fur brush, felt, and cloth can be used. In addition, it is possible to obtain more appropriate elasticity, conductivity, surface properties and durability by combining various materials.

4) As a waveform of an alternating voltage component (AC component, a voltage whose voltage value changes periodically) of the oscillating electric field applied to the contact charging member or the developing member, a sine wave, a rectangular wave, a triangular wave, or the like can be used as appropriate. It is. It may be a rectangular wave formed by periodically turning on / off a DC power supply.

5) The image exposure means as information writing means on the charged surface of the photoreceptor as the image carrier is not limited to the laser scanning means of the embodiment, but may be a digital exposure using a solid light emitting element array such as an LED. It may be a means. An analog image exposure unit using a halogen lamp, a fluorescent lamp, or the like as a document illumination light source may be used. In short, any device that can form an electrostatic latent image corresponding to image information may be used.

6) The image carrier may be an electrostatic recording dielectric or the like. In this case, after uniformly charging the dielectric surface,
The charged surface is selectively discharged by a discharging means such as a discharging needle head or an electron gun to write and form an electrostatic latent image corresponding to target image information.

7) The toner developing method and means of the electrostatic latent image are optional. A reversal development system or a regular development system may be used.

Generally, a method of developing an electrostatic latent image is to coat a non-magnetic toner on a developer carrying member such as a sleeve with a blade or the like, and to coat the magnetic toner with the developer carrying member. A method of applying an electrostatic latent image on the image carrier in a non-contact state by applying a magnetic force on the image carrier, conveying the image, and developing the electrostatic latent image (one-component non-contact development);
A method of applying the toner coated on the developer carrying member as described above to the image carrier in a contact state to develop an electrostatic latent image (one-component contact development); A method (two-component contact development) in which a mixture of the above is used as a developer (two-component developer) to be conveyed by magnetic force and applied in a contact state to an image carrier to develop an electrostatic latent image; The two-component developer is applied to the image carrier in a non-contact state to develop an electrostatic latent image (two-component non-contact development).

8) The transfer means is not limited to the roller transfer of the embodiment, but may be a blade transfer, a belt transfer or another contact transfer charging system, or a non-contact transfer charging system using a corona charger. .

9) The present invention can be applied not only to the formation of a single-color image but also to an image forming apparatus for forming a multi-color or full-color image by a multiple transfer method using an intermediate transfer member such as a transfer drum or a transfer belt.

[0078]

As described above, according to the present invention, the current waveform is captured using the means (integrating circuit) for measuring the integrated value of the current waveform, and the integrated value of the current waveform is measured by the integrating circuit. By controlling the power supply so that is constant, current control can be performed accurately, using a current value control method of a constant current method that is also advantageous in cost, a power supply device, a charging method, a charging device, and An image forming apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration model diagram of an image forming apparatus (cleanerless) according to an embodiment.

FIG. 2 is a schematic diagram of a layer configuration of a photosensitive drum and a charging roller.

FIG. 3 is a block circuit diagram of a power supply device.

4A is an AC current waveform (sine wave), and FIG. 4B is an AC current waveform (using an absolute value circuit).

FIG. 5A is an AC voltage waveform (frequency 1000H);
z, peak-to-peak voltage 700 V, sine wave), (b) is the current waveform flowing to the charging roller

6A is a current waveform (in the case of an AC voltage peak-to-peak voltage of 1100 V), and FIG. 6B is a current waveform (in the case of AC voltage peak-to-peak voltage of 1800 V).

FIG. 7 is a schematic configuration diagram of an image forming apparatus (with a cleaner) according to another embodiment.

[Explanation of symbols]

1. Photoconductor drum (image carrier), 2. Charging roller,
3. Laser beam scanner, 4. Developing device, 5.
Transfer roller, 6 fixing device, 7 toner charging control means, 8 cleaning device, S1 to S4 bias power supply, 11 DC power, 12 AC power,
13. Integrator, 14 CPU

Continued on the front page F term (reference) 2H003 BB11 CC05 DD03 EE11 2H027 ED03 ZA01 9A001 GG03 HH31 JJ35 KK31 KK37 KK42 LL02

Claims (14)

[Claims] 1. A power supply apparatus comprising: a power supply for generating a voltage; and means for measuring an integrated value of a current waveform, and outputting a voltage so that the integrated value of the current waveform per unit time is constant. . 2. The power supply device according to claim 1, further comprising a voltage of a DC component and a voltage of an AC component. 3. A charging method for charging a member to be charged by applying a voltage to a charging member in contact with the member to be charged, wherein the voltage applied to the charging member has a constant integral value per unit time of a current waveform. A charging method, characterized in that the charging is controlled so that 4. The charging method according to claim 3, wherein the voltage applied to said charging means is a voltage having a DC component and an AC component. 5. The charging method according to claim 4, wherein the absolute value of the amplitude of the current waveform of the AC component is integrated. 6. The charging method according to claim 1, wherein said charging means has a roller shape. 7. A charging apparatus comprising: a charging unit in contact with an object to be charged; and a power supply unit for outputting a voltage applied to the charging unit, wherein the power supply unit includes: a power supply for generating a voltage; , And outputting a voltage to be applied to the charging means so that the integrated value of the current waveform per unit time is constant. 8. The charging device according to claim 7, wherein the voltage applied to said charging means is a voltage having a DC component and an AC component. 9. The charging device according to claim 8, wherein the absolute value of the amplitude of the current waveform of the AC component is integrated. 10. A charging device according to claim 7, wherein said charging means has a roller shape. 11. An image forming apparatus for forming an image by applying an image forming process including a step of charging the image carrier to the image carrier, wherein the charging device for charging the image carrier is an image carrier. And a power supply for outputting a voltage to be applied to the charging means. The power supply has a power supply for generating a voltage, and a means for measuring an integrated value of a current waveform. An image forming apparatus for outputting a voltage to be applied to the charging unit so that an integral value per unit time of the charging unit becomes constant. 12. The image forming apparatus according to claim 11, wherein the voltage applied to said charging means is a voltage having a DC component and an AC component. 13. The image forming apparatus according to claim 12, wherein the absolute value of the amplitude of the AC component current waveform is integrated. 14. An image forming apparatus according to claim 11, wherein said charging means has a roller shape.