JP2007187933A - Charging controller and inflection point detecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging controller capable of controlling to attain an optimum AC voltage or AC current in a short time by shortening a time for detecting an inflection point where a charged body changes from an unsaturated state to a saturated state. <P>SOLUTION: The charging controller 10 that detects the inflection point where the photoreceptor 2 changes from the unsaturated state to the saturated state by supplying the DC voltage with an AC current superposed to the photoreceptor 2 and measuring a DC current flowing in the photoreceptor 2 while changing the value of the AC current includes: a charging roll 3 arranged in contact or adjacent to the photoreceptor 2, provided to charge the photoreceptor 2; a DC current detecting part 12 provided to supply the DC voltage with the AC current superposed to the charging roll 3 and measure the DC current; and a control part 13 provided to turn off erasing, to integrate the DC current flowing in a period including one rotation of the photoreceptor until the erasing-off area on the photoreceptor reaches the position in contact with or adjacent to the charging member and the DC current flowing until the photoreceptor 2 is saturated, then, to calculate the changing range of the AC current based on the integrated value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charging control device that charges a member to be charged by a contact charging method using discharge as a charging principle, supplying an AC current or an AC voltage to a charging device with a DC voltage superimposed thereon.

  Conventionally, as a charging device, there is a contact type charging device in which a charging member such as a roller or a blade to which a voltage is applied is brought into contact with the surface of a charged body such as a photoconductor to charge the surface of the charged body to a predetermined polarity and potential. It is used.

In this contact-type charging device, a method in which an AC voltage or an AC current is superimposed on a DC voltage and applied is applied to the charging device. Only by applying a DC voltage, a current flows only at a low resistance on the photoconductor, so that it cannot be uniformly charged. Further, when the surface of the photosensitive member is locally soiled, there arises a problem that only that portion is not charged. Therefore, the surface of the photoreceptor is charged by applying an AC voltage or an AC current superimposed on the DC voltage.
Here, the AC voltage or AC current includes a case where the AC voltage is superimposed on the DC voltage and applied to the charging device, and the AC current flowing at that time is controlled to be constant.

  However, if the AC voltage or AC current is too large, the wear of the photoreceptor is affected. On the other hand, if it is too small, the uniformity of charging cannot be maintained, and unevenness occurs when printed. For this reason, it is necessary to correct the AC voltage or AC current to the minimum necessary optimum value as needed.

  In Patent Document 1, as shown in FIG. 1, the AC current applied to the charging device is sequentially increased, and the saturation potential of the photoconductor is detected by measuring the DC current flowing into the charging device at that time, and applied to the photoconductor. A technique for controlling the AC value is disclosed. The saturation potential of the member to be charged indicates a DC voltage at an inflection point at which the member to be charged changes from unsaturated to saturated as shown in FIG.

JP 2004-333789 A

  In the method in which the AC current applied to the charging device is sequentially increased as in Patent Document 1 and the saturation potential of the photosensitive member is detected by the DC current flowing into the charging member at that time, it takes time to detect the saturation potential. . That is, many measurements must be performed from the unsaturated region to the saturated region of the photoconductor, which takes a lot of time.

  Further, when the operating environment changes immediately after the image forming apparatus is started up, the inflection point also changes, so that it is necessary to update the AC current to be applied in response to the environmental change. In the method of setting the AC current by sequentially applying the AC current, if the control is frequently performed, the wear of the photoconductor progresses due to the control.

  Further, when the AC current value is swept in the unsaturated region before the charged body is saturated, the surface potential of the charged body also varies depending on the environment. For this reason, when the surface potential of the photoreceptor is too lower than the developing bias, toner fog occurs and the toner is scattered. Further, if the AC current to be applied is excessively larger than the inflection point, the discharge product covers the surface of the photoconductor, causing a problem of image quality degradation. Since this discharge product does not fall off easily, application of excessive AC current must be avoided.

  FIG. 2A shows a change in potential on the surface of the charged body when the amplitude of the AC current (Iac) passed through the charged body is changed. 2 (B) and 2 (C) are diagrams showing the DC current (Idc) that has flowed through the member to be charged when the amplitude of the AC current (Iac) is changed, and FIG. The case where the thickness of the charged body is thin is shown, and (C) shows the case where the thickness of the charged body is thick. As can be seen from FIGS. 2A to 2C, the DC current (Idc) flowing through the charged body increases as the film thickness decreases even though the surface potential of the charged body does not change. . For this reason, the optimal AC current value cannot be determined by the absolute value of the DC current (Idc).

  The present invention has been made in view of the above circumstances, and can reduce the detection time of an inflection point at which an object to be charged changes from unsaturated to saturated, and can be controlled to an optimal AC voltage or AC current in a short time. An object is to provide a charging control device and an inflection point detection method.

In order to achieve such an object, the charge control device of the present invention supplies an AC current or AC voltage superimposed on a DC voltage to the object to be charged, and changes the value of the AC current or AC voltage. A charging control device that detects an inflection point at which the charged body changes from unsaturated to saturated by measuring a direct current flowing through the charged body, and is disposed in contact with or close to the charged body. A charging member that charges the member to be charged, a measuring unit that measures the direct current, and the direct current that flows until the surface potential of the member to be charged is saturated from the potential after the charge removal. And a control unit for calculating a range of the value of the alternating current or the alternating voltage to be changed.
Since the integrated value of the direct current that flows until the body to be charged is saturated is determined only by the film thickness of the body to be charged, an AC voltage or AC current range is set near the inflection point even if the environment changes. be able to. Accordingly, it is possible to shorten the time until the inflection point is calculated.
Furthermore, since the AC current or the AC voltage is not greatly deviated from the inflection point when the inflection point is detected, it is possible to prevent toner fogging and application of an excessive AC current / AC voltage.

  In the charging control device, the control unit may perform integration during a period including from the start of integration until the charging member reaches a region where the charge-off lamp is turned off on the object to be charged.

  In the charging control device, the control unit includes an integrated value of the direct current that flows until the charged body after charge removal makes one round, and the direct current that flows until the charged object after discharge is saturated. And the AC current based on the AC voltage or AC current when the ratio between the DC current integrated value for one round and the DC current integrated value until saturation is a constant ratio. Alternatively, the range of AC voltage values may be calculated.

  In the charging control device, the control unit is configured such that the DC current flowing from the object to be charged is integrated for a predetermined period, an average current value obtained from the number of integrations in the predetermined period, and the object to be charged is saturated. When the saturation average current value obtained from the integrated value of the DC current flowing until the saturation and the number of integrations until saturation is obtained, and the ratio of the average current value and the saturation average current value is a constant ratio The range of the value of the AC current or AC voltage may be calculated based on the AC voltage or AC current.

  In the charging control apparatus, the control unit obtains a slope of a straight line indicating a relationship between an AC current or an AC voltage to be applied and a DC current measured at that time in the unsaturated region of the charged object, The value of the alternating current or the alternating voltage when taking the integrated value of the direct current flowing until the saturation of the alternating current is obtained by extrapolation, and the value of the alternating current or the alternating voltage is calculated based on the alternating current or the alternating voltage value. The range should be calculated.

  In the charging control device, the control unit may change the constant ratio according to an environment.

In the charging control device, the control unit charges the charged object by superimposing the alternating voltage or the alternating current on the direct current voltage set to 0 V after discharging the charged voltage of the charged object with a static elimination lamp. Then, the obtained integrated value may be added as a residual charge amount to the denominator numerator at the time of calculating the ratio.
Accordingly, since the residual charge amount can be detected with high accuracy, it is possible to detect in advance the image quality deterioration of the charged body. Furthermore, image control can be performed with high accuracy without using a surface electrometer or the like.

  In the charging control device, it is preferable to calculate a residual potential after static elimination from the residual charge amount.

  In the inflection point detection method of the present invention, an alternating current or an alternating voltage is superimposed on a direct current voltage and supplied to the member to be charged, and the alternating current or alternating voltage is changed while the value of the alternating current or the alternating voltage is changed. An inflection point detecting method for detecting an inflection point at which the charged body changes from unsaturated to saturated by measuring a flowing direct current, wherein the surface potential of the charged body is saturated from the potential after the charge removal. It is preferable to integrate the DC current flowing up to and calculate the range of the AC current or AC voltage value to be changed from the integrated value.

  According to the present invention, the detection time of the inflection point where the charged body changes from unsaturated to saturated can be shortened, and the optimum AC voltage or AC current can be controlled in a short time.

  Preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  First, the configuration of the present embodiment will be described with reference to FIG. The photoconductor 2 as an image carrier is a cylindrical OPC photoconductor, and is driven to rotate at a predetermined process speed (circumferential speed) in the clockwise direction indicated by an arrow about a central axis perpendicular to the paper surface.

  Around the photoreceptor 2, a charging roll 3 brought into contact with the photoreceptor 2, a ROS (Raster Optical Scanner) 4 as an exposure device, a developing device 5, a cleaning blade 7, a charge removal lamp 8 and the like are disposed.

  The charging roll 3 rotates following the rotation of the photosensitive member 2 and is supplied with an AC + DC voltage or current from the power supply unit 11 so that the peripheral surface of the rotating photosensitive member 2 is uniformly charged to a predetermined polarity and potential. (In this example, it is negatively charged).

  Next, an image-modulated laser beam output from the ROS 4 is irradiated (scanning exposure) onto the charging surface of the rotating photosensitive member 2, and the potential of the exposed portion is attenuated to form an electrostatic latent image.

  When the latent image arrives at the developing portion facing the developing device 5 as the photosensitive member 2 rotates, negatively charged toner is supplied from the developing device 5 and a toner image is formed by reversal development.

  An electroconductive transfer roll 6 is disposed in pressure contact with the photoconductor 2 on the downstream side of the developing device 5 when viewed in the rotation direction of the photoconductor 2, and a nip portion between the photoconductor 2 and the transfer roll 6 serves as a transfer site. Forming.

  When the toner image formed on the surface of the photoconductor 2 reaches the transfer site as the photoconductor 2 rotates, the paper is supplied to the transfer position at the same time, and a predetermined voltage is applied to the transfer roll 6 at the same time. Thus, the toner image is transferred from the surface of the photoreceptor 2 to the sheet.

  The sheet that has received the toner image transfer at the transfer position is conveyed to the fixing device 9 where the toner image is fixed and discharged outside the apparatus.

  On the other hand, the untransferred toner remaining on the surface of the photosensitive member 2 is scraped off by the cleaning blade 7, whereby the surface of the photosensitive member 2 is cleaned and prepared for the next image formation. Further, the electrostatic latent image on the photosensitive member 2 is erased by the charge eliminating lamp 8.

  Furthermore, in this embodiment, a charging control device 10 that controls the AC current value applied to the photosensitive member 2 is provided. The charging control device 10 includes a power supply unit 11, a DC current detection unit 12, and a control unit 13. The power supply unit 11 has a configuration in which a DC power supply 15 and an AC power supply 14 are connected in series, and supplies the charging roll 3 with an AC current superimposed on a DC voltage. The DC current detection unit 12 measures the DC current flowing from the charging roll 3 into the photoconductor 2 and outputs the measured value to the control unit 13.

  FIG. 4 shows a detailed configuration of the control unit 13. As shown in FIG. 4, the control unit 13 includes a timing control unit 21, an adder 22, a saturated DC current value holding unit 23, a divider 24, an unsaturated region inclination detection unit 25, a sweep start AC value calculation / holding unit 26, A sweep end AC value calculating / holding unit 27, an AC value indicating unit 28, a previous AC value holding unit 29, a comparator 30, an adder 31, and a step value holding unit 32 are provided.

  The timing control unit 21 is connected to the static elimination lamp 8, the DC current detection unit 12, and the DC power source 15. The timing control unit 21 turns off the current to the static elimination lamp 8 and the transfer roll 6 while measuring the saturation DC current of the photoreceptor. In addition, the timing control unit 21 controls the on / off of the DC current detection unit 22. Further, the timing control unit 21 controls the DC power supply 15 to switch between two voltages V1 and V2 having a potential difference from the base material of the photoreceptor 2. The voltages V1 and V2 are voltages determined according to the image forming process.

  The adder 22 adds the DC current value measured by the DC current detection unit 12 over a plurality of circumferences of the photosensitive member 2 to obtain a DC current value that flows until the photosensitive member 2 is saturated. The calculated saturation DC current value is stored in the saturation DC current value holding unit 23.

  The divider 24 divides the saturation DC current value held in the holding unit 23 by a predetermined value (for example, 2) to set a sweep range for detecting an inflection point at which the photosensitive member 2 changes from unsaturated to saturated. To do. The unsaturated region inclination detection unit 25 applies AC currents having different values to the photosensitive member 2 a plurality of times, and obtains the inclination of the Idc-Iac line in the unsaturated region of the photosensitive member 2 from the detected DC current. . Further, an AC current at the start of charging when the photosensitive member 2 starts charging is also obtained. Note that the AC current applied at this time sets the value of the unsaturated region of the photoreceptor 2 shown in FIG. In this measurement, not only an AC current but also a DC voltage is applied to the photoreceptor 2.

  The sweep start AC value calculation / holding unit 26 calculates and holds the sweep start AC value for starting the sweep of the AC current. The sweep end AC value calculation / hold 27 calculates and holds a sweep end AC value for ending the sweep of the AC current.

  The AC value instruction unit 28 instructs an AC current value to be instructed to the AC power supply 14. The previous AC holding unit 29 holds the AC value instructed to the AC power supply 14 last time. The comparator 30 compares the sweep end AC value held in the sweep end AC value calculating / holding unit 27 with the previous AC value held in the previous AC value holding unit 29. The comparator 30 stops the output of the adder 31 when the previously instructed AC value matches the sweep end AC value. Further, when the previously instructed AC value is smaller than the sweep end AC value, the adder 31 is instructed to output the next AC value. The adder 31 adds the step value held in the step value holding unit 32 to the previous AC value, generates the current AC value, and outputs it to the AC value instruction unit 28.

In order to detect the optimum AC current value to be applied to the photoreceptor 2 at an early stage, the charging control device 10 of this embodiment narrows down the sweep range in which the AC current is swept.
FIG. 5A shows a change in the photoreceptor surface voltage after the static elimination lamp 8 is turned off, and FIG. 5B shows a DC current flowing until the photoreceptor 2 is saturated. Due to the resistance of the charging roll 3, the photoreceptor 2 must rotate a plurality of times before saturation as shown in FIG. At this time, the DC current that flows until the photosensitive member 2 is saturated is integrated, and this is divided by the number of integrations of the DC current per rotation of the photosensitive member to calculate the saturated DC current. The amount of saturation DC current is not affected by the charging roll 3 and is a value corresponding to the film thickness of the photoreceptor 2. A sweep range for sweeping the AC current is defined based on the saturation DC current. The saturation DC current is determined by the film thickness of the photosensitive member 2, and the DC current measured in the saturation region from the state where the charge is eliminated even when the environment changes is always smaller than the saturation DC current, and only the difference due to environmental fluctuations. Thus, the AC current range can be set near the inflection point. Accordingly, it is possible to shorten the time until the inflection point is calculated. Further, since the AC current does not greatly deviate from the inflection point when the inflection point is detected, it is possible to prevent toner fog and application of an excessive AC current.

  First, the saturation DC current value is multiplied by a predetermined value to obtain the lower limit value of the AC current to be swept. The saturation DC current value is divided by a predetermined value, and an AC value (hereinafter, this value is referred to as Iac (Start)) when the value is taken is obtained. The slope of the Iac-Idc straight line in the unsaturated region of the photoconductor 2 and the value of the AC current at the start of charging when the photoconductor 2 starts to be charged are obtained in advance by the unsaturated region tilt detector 25 according to the procedure described above. deep. FIG. 6 illustrates a case where the value of the saturation DC current is divided by [2] by the divider 24. The AC current value Iac (Start) when taking the value of 0.5 × saturated DC current is obtained from the slope of the Iac-Idc straight line and the AC current at the start of charging when the photosensitive member 2 starts charging.

  Next, an upper limit value (hereinafter, this value is referred to as Iac (End)) for sweeping the AC current is obtained. As shown in FIG. 6, the value of Iac (End) is obtained by extrapolating the intersection of the Iac-Idc line in the unsaturated region and the saturated DC current. The AC current value obtained by this extrapolation is set to Iac (End).

  By setting Iac (Start) and Iac (End) in this way, the inflection point of the photoconductor can always be included in this range as shown in FIG. The AC current value can be detected early.

  In the above-described example, the saturation DC current is divided by 2 in the divider 24, but this value can be arbitrarily set according to the environment or the like. For example, as shown in FIG. 7A, under a high temperature and high humidity environment, the AC current applied at the inflection point is small and the measured DC current is large. Under a low temperature and low humidity environment, the AC current is applied at the inflection point. AC current is large, and the measured DC current is small. For this reason, as shown in FIGS. 7B and 7C, the AC current value at the inflection point is changed by changing the value divided by the divider 24 between high temperature and high pressure and low temperature and low humidity. The time until detection can be further shortened.

The operation procedure of the control unit 13 will be described with reference to the flowchart of FIG. 8 and FIG. FIG. 9 shows an AC current and a DC voltage applied to the photosensitive member 2 and a DC current flowing through the photosensitive member 2 and a change in the photosensitive member surface potential.
The saturation DC current can be calculated by calculation when the thickness of the photosensitive member 2 is known at the start of use. For this reason, here, it is assumed that the control is started and the saturation DC current is detected and updated after the control. First, a constant ratio (here, 50%) of the saturation DC current is obtained with respect to the saturation DC current, and the AC current is controlled so as to coincide with 50% of the saturation DC current during the constant current control period ( Step S1, or period A) shown in FIG.

  Next, the AC current value after the control is set as the AC current sweep start point Iac (Start), and the sweep is started. As described above, the unsaturated region inclination detection unit 25 obtains the inclination of the Iac-Idc straight line in the unsaturated region, the AC current at the start of charging, etc., and extrapolates at the intersection of the Iac-Idc straight line and the saturated DC current. AC current value is obtained. This intersection point is defined as the sweep end AC current Iac (End), and the AC current is swept to this Iac (End), and the DC current flowing into the photosensitive member 2 at that time is measured (step S2 and period B shown in FIG. 9).

  Next, an inflection point at which the photosensitive member 2 changes from unsaturated to saturation is detected from the measured DC current (step S3), and a margin α is added to the AC value at this inflection point to print an AC current value at the time of printing. Set. An AC current of AC + α is superimposed on the DC voltage and applied to the photoreceptor 2 (step S4).

  Next, the saturation DC current is obtained by using the DC current value measured at the time of printing, and the saturation DC current value is updated (step S5, period C shown in FIG. 9). The saturation DC current is calculated by first erasing the surface potential of the photoreceptor 2 and then turning off the charge removal lamp 8. Then, the DC current value is integrated for a period during which the photosensitive member surface potential is saturated, and this is divided by the integrated number of DC currents per rotation of the photosensitive member to calculate a saturated DC current. In FIG. 9, the DC currents in the periods D, E, and F in which the surface potential of the photoconductor becomes the DC voltage V2 among the voltages applied to the charging roll 3 are integrated to obtain a saturated DC current. When the calculation is completed, the saturation DC current is updated.

  Further, when the charge is removed by the charge removal lamp 8, the surface potential of the photosensitive member 2 does not become 0V, and a residual charge may remain. Such residual charge reduces the saturation DC current and causes an error in the ratio calculation. Therefore, after the charge voltage of the photoconductor 2 is neutralized by the static elimination lamp 8, the AC current is superimposed on the DC voltage set to V1 to charge the photoconductor 2, and the obtained saturated DC current is used as the residual charge amount. Can be detected. Since V1 is set to 0V and charged with a DC voltage, the photoreceptor 2 can be accurately discharged. Therefore, by adding the saturation DC current obtained as the residual charge and adding it to the saturation DC current obtained when the DC voltage applied to the photoreceptor 2 is V2, the accuracy in the AC range in saturation detection is suppressed by suppressing the error in the ratio calculation. Can be raised.

  The control unit 13 shown in FIG. 4 can also be realized by software control by computer processing. A DC current detected by the DC current detection unit 12 is input to the control unit 13, and a saturation DC current, Iac (Start), Iac (End) is calculated by calculation by the CPU of the control unit 13. The calculation result is held in an internal memory of the control unit 13, and the CPU controls the AC current by comparing the detected DC current with Iac (Start) and Iac (End).

  In addition to the embodiments described above, the ratio between the saturation DC current that flows until the photoreceptor 2 after neutralization is saturated and the DC current that is detected in one round of the photoreceptor 2 after neutralization is obtained, and these ratios are obtained. It is also possible to control the AC current so that becomes a constant ratio. That is, the DC current that flows until the photosensitive member 2 that has been neutralized goes round is integrated, and the AC current is controlled so that this integrated value becomes a constant ratio (for example, 50%) of the saturation DC current. This AC value is Iac (Start). The photosensitive member surface potential is predicted from the target charging current since the charging current / saturation DC current corresponds to the photosensitive member surface potential, and the DC current detected in one round of the photosensitive member 2, that is, the ratio of the charging current to the saturation DC current. The development bias is set based on the value.

  Further, instead of obtaining the DC current or the saturation DC current based on the rotational speed of the photosensitive member 2, a predetermined period can be set and obtained from the DC current in this period. That is, the integrated value obtained by integrating the DC current flowing from the photosensitive member 2 for a predetermined period, the average current value obtained from the number of integrations in the predetermined period, the integrated value of the DC current flowing until the photosensitive member 2 is saturated, and the saturation The range of AC values may be calculated based on the AC current when the saturation average current value obtained from the number of integrations up to this time is constant.

  Further, when the ratio is obtained, an error can be eliminated by adding the residual charge obtained by the above-described procedure to the denominator numerator. Further, the surface potential of the photoconductor after erasure can be estimated from the residual charge amount and the photoconductor film thickness, and whether or not the residual potential is corrected can be determined from this estimated value.

  The embodiment described above is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the photoconductor 2 is charged by applying an AC current, but an AC voltage can also be applied.

It is a figure which shows the relationship between Iac applied to a photoreceptor, and measured Idc. It is a figure which shows the fluctuation | variation by the environment of an Iac-Idc curve. 1 is a diagram illustrating a configuration of an image forming apparatus. It is a figure which shows the structure of a control part. It is a figure which shows the change of the surface potential until a photoreceptor is saturated, and the measured DC current. It is a figure which shows the range which sweeps AC electric current. It is a figure which shows the example which changes the sweep range according to an environment. It is a flowchart which determines the sweep range of AC current. It is a figure which shows the change of DC voltage and AC current applied to a photoconductor, the surface potential of the photoconductor at that time, and DC current.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photoconductor 3 Charging roll 4 Exposure device 5 Developing device 6 Transfer roll 7 Cleaning blade 8 Static elimination lamp 9 Fixing device 10 Charge control device 11 Power supply part 12 DC current detection part 13 Control part 14 AC power supply 15 DC power supply

Claims (9)

Supplying to the object to be charged after removing the charge by superimposing the alternating current or the alternating voltage on the direct current voltage, measuring the direct current flowing through the charged object while changing the value of the alternating current or the alternating voltage, A charging control device for detecting an inflection point where a charged body changes from unsaturated to saturated,
A charging member that is disposed in contact with or in proximity to the member to be charged and charges the member to be charged;
A measuring unit for measuring the direct current;
A controller that integrates the direct current flowing until the surface potential of the member to be charged saturates from the potential after the charge removal, and calculates a range of the alternating current or alternating voltage value to be changed from the integrated value. A charge control device characterized by that.   The charge control device according to claim 1, wherein the control unit performs the accumulation in a period including a period from the start of accumulation until the charging member reaches an area where the charge removal lamp is turned off on the object to be charged. The control unit obtains an integrated value of the direct current that flows until the charged body after static elimination makes a round, and an integrated value of the direct current that flows until the charged body after saturation is saturated. ,
Range of the value of the alternating current or alternating voltage based on the alternating voltage or alternating current when the ratio of the integrated value of the direct current for one round and the integrated value of the direct current until saturation is a constant ratio The charge control device according to claim 1, wherein: The control unit includes an integrated value obtained by integrating the DC current flowing from the charged body for a predetermined period, an average current value obtained from the number of integrations in the predetermined period, and the flowing current until the charged body is saturated. Obtain the integrated value of DC current and the saturation average current value obtained from the number of integrations until saturation,
2. The range of the value of the AC current or AC voltage is calculated based on the AC voltage or AC current when the ratio of the average current value and the saturation average current value is a constant ratio. The charging control device described.   The control unit obtains a slope of a straight line indicating a relationship between an AC current or AC voltage to be applied and a DC current measured at that time in the unsaturated region of the charged body, and flows until the straight line is saturated. Obtaining the value of the alternating current or the alternating voltage when taking the integrated value of the direct current by extrapolation, and calculating the range of the alternating current or the alternating voltage based on the alternating current or the alternating voltage value The charge control device according to claim 1, wherein   The charging control apparatus according to claim 3, wherein the control unit changes the constant ratio according to an environment.   The control unit charges the charged object by superimposing the alternating voltage or alternating current on the direct-current voltage set to 0 V after the charge voltage of the charged object is discharged by a charge-removing lamp. 5. The charge control device according to claim 3, wherein a value is added as a residual charge amount to a denominator numerator at the time of calculating the ratio.   The charging control device according to claim 7, wherein the control unit calculates a residual potential after static elimination from the residual charge amount. Supplying to the object to be charged after removing the charge by superimposing the alternating current or the alternating voltage on the direct current voltage, measuring the direct current flowing through the charged object while changing the value of the alternating current or the alternating voltage, An inflection point detection method for detecting an inflection point at which an object to be charged changes from unsaturated to saturated,
The DC current flowing until the surface potential of the member to be charged saturates from the potential after neutralization is integrated, and the range of the AC current or AC voltage value to be changed is calculated from the integrated value. Music point detection method.

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