JP4877648B2 - Charging control device, charging device, image forming apparatus, and charging control program - Google Patents

Description

  The present invention relates to a charging control device, a charging device, an image forming apparatus, and a charging control program.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses an image forming apparatus that determines a charging bias for charging a photosensitive member by multiplying a predetermined ratio with respect to a point of AC current at which a DC current value is saturated. Further, Patent Document 2 discloses a discharge current amount by controlling the output of an AC power supply so that a difference between a current flowing between the image carrier and the charging member and a preset current value becomes a predetermined value. An image forming apparatus that suppresses fluctuations of the image is disclosed. Further, Patent Document 3 compares the fluctuation range of the DC component of the bias power source to which the DC component and the AC component are applied in a superimposed manner with the fluctuation reference value. When the fluctuation width becomes a value lower than the fluctuation reference value, An image forming apparatus that performs charging using a peak voltage value as a bias voltage is disclosed.

JP 2004-333789 A JP 2002-072633 A Japanese Patent No. 3416826

  However, the image forming apparatuses disclosed in Patent Document 1 and Patent Document 2 perform control using a predetermined value determined in advance through experiments, and it is very labor-intensive to determine a predetermined value that is not correlated with image quality. There was a problem that it was necessary. Further, the image forming apparatus disclosed in Patent Document 3 has a problem in that the measurement time required to obtain the accuracy capable of preventing the density unevenness of the image becomes long due to the variation in the detected direct current value. It was.

  It is an object of the present invention to provide a charge control device, a charging device, an image forming apparatus, and a charge control program that can easily prevent deterioration in image quality and shortening of the life of an image carrier.

In order to achieve the above object, the present invention according to claim 1 is a discharge charge amount detection means for detecting a charge amount of a discharge generated according to an alternating current supplied to a charging member for charging a member to be charged. DC current detecting means for detecting a DC current supplied to the charging member, variation obtaining means for obtaining a variation in the DC current detected by the DC current detecting means in correspondence with the AC current value, and a change in the AC current A change amount acquisition means for acquiring a change amount with respect to the variation acquired by the variation acquisition means, and a target of the charge amount detected by the discharge charge amount detection means according to the change amount acquired by the change amount acquisition means A target value defining means for defining a value, an alternating current for adjusting the alternating current supplied to the charging member according to the target value defined by the target value defining means and the charge amount detected by the discharge charge amount detecting means. A current adjustment unit, a charging control device having a.

  According to a second aspect of the present invention, the target value defining means is configured such that when the change amount acquired by the change amount acquiring means reaches a saturated state or a predetermined value or less as the alternating current increases, the discharge charge The charge control device according to claim 1, wherein the charge amount detected by the amount detection means is defined as a target value.

The present invention according to claim 3 is characterized in that the variation acquisition means acquires the standard deviation, variance, or difference between the maximum value and the minimum value of the DC current as variations corresponding to the AC current value . This is a charge control device.

According to a fourth aspect of the present invention, there is provided a charging member for charging an object to be charged, a discharge charge amount detecting means for detecting a charge amount of discharge generated according to an alternating current supplied to the charging member, and a charging member. DC current detection means for detecting the supplied DC current , variation acquisition means for acquiring the variation in DC current detected by the DC current detection means in correspondence with the AC current value, and the amount of change with respect to the change in AC current. A change amount acquisition unit that acquires the variation acquired by the variation acquisition unit, and a target value of the charge amount detected by the discharge charge amount detection unit according to the change amount acquired by the change amount acquisition unit AC current adjustment for adjusting the AC current supplied to the charging member in accordance with the target value defining means to be performed and the target value defined by the target value defining means and the charge amount detected by the discharge charge amount detecting means And the step, a charging device having a.

  According to a fifth aspect of the present invention, the target value defining means is configured such that when the change amount acquired by the change amount acquiring means reaches a saturated state or a predetermined value or less as the alternating current increases, the discharge charge The charging device according to claim 4, wherein the charge amount detected by the amount detection means is defined as a target value.

The present invention according to claim 6 is characterized in that the variation acquisition means acquires the standard deviation, dispersion, or difference between the maximum value and the minimum value of the DC current as variations corresponding to the AC current value . It is a charging device.

According to a seventh aspect of the present invention, there is provided an image carrier, a charging member for charging the image carrier, a power feeding unit for supplying a current obtained by superimposing a direct current and an alternating current on the charging member, and the power feeding unit. a discharge charge amount detection means but of detecting the charge amount of discharge generated in response to the alternating current supplied to the charging member, a DC current detecting means for detecting the direct current supplied to the charging member, the DC current detection Variation obtaining means for obtaining the variation in the direct current detected by the means in correspondence with the alternating current value, and change amount obtaining means for obtaining the change amount for the change in the alternating current with respect to the variation obtained by the variation obtaining means. And target value defining means for defining a target value of the charge amount detected by the discharge charge amount detecting means according to the change amount acquired by the change amount acquiring means, and a target defined by the target value defining means Wherein in accordance with the amount of charge discharged charge amount detection means detects a, an image forming apparatus having an AC current adjusting means for adjusting the alternating current supplied to the charging member.

  The present invention according to claim 8 is characterized in that the target value defining means has the discharge charge when the change amount acquired by the change amount acquiring means reaches a saturated state or a predetermined value or less as the alternating current increases. The image forming apparatus according to claim 7, wherein the charge amount detected by the amount detection unit is defined as a target value.

The present invention according to claim 9 is characterized in that the variation acquisition means acquires the standard deviation of DC current, variance, or the difference between the maximum value and the minimum value as variations corresponding to the AC current value . An image forming apparatus.

According to a tenth aspect of the present invention, there is provided a step of detecting a discharge charge amount generated in response to an alternating current supplied to a charging member that charges a member to be charged, and a step of detecting a direct current supplied to the charging member. , the variation in the detected DC current, and obtaining in correspondence to the alternating current, and obtaining the amount of change in the variation with respect to the change of the alternating current, the eyes of the discharge charge quantity according to the obtained amount of change And a step of adjusting the alternating current supplied to the charging member in accordance with the defined target value and the detected discharge charge amount.

  According to the present invention, it is possible to easily prevent deterioration in image quality and shortening of the life of an image carrier.

Next, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show an outline of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12, an image forming unit 14 is mounted in the image forming apparatus main body 12, and a discharge unit 16 described later is provided on the upper portion of the image forming apparatus main body 12. In addition, for example, two-stage sheet feeding units 18 a and 18 b are disposed below the image forming apparatus main body 12. Further, below the image forming apparatus main body 12, two-stage sheet feeding units 18c and 18d that are detachably mounted as options are arranged.

  Each of the paper feeding units 18a to 18d has a paper feeding unit main body 20 and a paper feeding cassette 22 in which paper is stored. The paper feed cassette 22 is slidably attached to the paper feed unit main body 20 and is pulled out in the front direction (right direction in FIG. 1). In addition, a paper feed roll 24 is disposed in the upper portion near the rear end of the paper feed cassette 22, and a retard roll 26 and a feed roll 28 are disposed in front of the paper feed roll 24. Further, the optional paper feed units 18c and 18d are provided with a pair of feed rolls 30 respectively.

  The conveyance path 32 is a sheet path from the feed roll 30 to the discharge port 34 of the lowermost sheet feeding unit 18d, and this conveyance path 32 is near the back surface (left side surface in FIG. 1) of the image forming apparatus main body 12. The lowermost sheet feeding unit 18d has a portion formed substantially vertically from the feed roll 30 to the fixing device 36 described later. A transfer device 42 and an image holding body 44 which will be described later are arranged on the upstream side of the fixing device 36 in the conveyance path 32, and a resist roll 38 is arranged on the upstream side of the transfer device 42 and the image holding body 44. Further, a discharge roll 40 is disposed in the vicinity of the discharge port 34 of the conveyance path 32.

  Accordingly, the recording medium fed from the paper feed cassette 22 of the paper feed units 18 a to 18 d by the feed roll 24 is drawn by the retard roll 26 and the feed roll 28 and guided to the transport path 32, and is temporarily stopped by the registration roll 38. The developer image is transferred between a transfer device 42 and an image carrier 44, which will be described later, at a timing, and the transferred developer image is fixed by the fixing device 36, and the discharge port 34 discharges the discharge port 34. To the discharge unit 16.

  However, in the case of duplex printing, it is returned to the reverse path. That is, the front side of the discharge roll 40 in the transport path 30 is divided into two forks, and a switching claw 46 is provided at the divided portion, and a reverse path 48 is formed from the divided portion to the registration roll 38. The reversing path 48 is provided with transport rolls 50a to 50c. In the case of double-sided printing, the switching claw 46 is switched to the side that opens the reversing path 48, and the discharge roll 40 is in front of the rear end of the recording medium. At that time, the discharge roll 40 is reversed, the recording medium is guided to the reverse path 48, and is discharged from the discharge port 34 to the discharge unit 16 through the registration roll 38, the transfer device 42, the image holding body 44 and the fixing device 36. It is.

  The discharge unit 16 includes an inclined part 52 that is rotatable with respect to the image forming apparatus main body. The inclined portion 52 has a lower discharge port portion and is inclined so as to gradually increase in the front direction (right direction in FIG. 1), with the discharge port portion as a lower end and a higher tip as an upper end. The inclined portion 52 is supported by the image forming apparatus main body 12 so as to be rotatable around the lower end. As shown by a two-dot chain line in FIG. 1, when the inclined portion 52 is rotated upward and opened, an opening portion 54 is formed, and a process cartridge 64 described later can be attached and detached through the opening portion 54. .

  The image forming means 14 is of, for example, an electrophotographic system, and includes an image holding member 44 made of a photosensitive member, a charging member 56 made of, for example, a charging roll that uniformly charges the image holding member 44 by pressure contact, and the charging member 56. An optical writing device 58 for writing a latent image to the image holding member 44 charged by the light, a developing device 60 for visualizing the latent image of the image holding member 44 formed by the optical writing device 58 with a developer, and Transferred by the developing device 60 to the paper, a transfer device 42 made of, for example, a transfer roll, a cleaning device 62 made of, for example, a blade for cleaning the developer remaining on the image carrier 44, and transferred by the transfer device 42. For example, the image forming apparatus includes a fixing device 36 including a pressure roll and a heating roll for fixing the developer image on the paper to the paper. The optical writing device 58 is composed of, for example, a scanning type laser exposure device, and is arranged in the vicinity of the front surface of the image forming apparatus main body 12 in parallel with the paper feeding units 18a to 18d described above, and the image carrier 44 is moved across the developing device 60. Exposure. The exposure position of the image carrier 44 is the latent image writing position P. In this embodiment, a scanning laser exposure apparatus is used as the optical writing device 58. However, an LED, a surface emitting laser, or the like can be used as another embodiment.

  The process cartridge 64 is obtained by integrating the image carrier 44, the charging member 56, the developing device 60, and the cleaning device 62. The process cartridge 64 is disposed immediately below the inclined portion 52 of the discharge portion 16 and is attached and detached through the opening portion 54 formed when the inclined portion 52 is opened as described above.

The image forming apparatus 10 includes a user interface device (UI device) 66 including a display device and a keyboard, a storage device 68 such as an HDD / CD device, a communication device 70, a control unit 72, and the like. The control unit 72 includes a CPU 74, a memory 76, and the like, and controls each unit constituting the image forming apparatus 10.
That is, the image forming apparatus 10 includes a function as a computer, and performs processing such as printing by executing a program received via the storage medium 78 or the communication device 70.

Next, the high voltage power supply unit 80 that applies a high voltage to the charging member 56 and the charge control device 82 that controls the current supplied to the charging member 56 by the high voltage power supply unit 80 will be described in detail.
FIG. 3 shows details of the high-voltage power supply unit 80, the charging control device 82, and the periphery thereof.
The high voltage power supply unit 80 includes a DC power supply 84 and an AC power supply 85, applies a predetermined voltage to the charging member 56, and supplies a current in which the DC component and the AC component are superimposed to the charging member 56. For example, the AC power supply 85 applies a voltage having a peak-to-peak voltage Vpp of about 1000 to 2500 V at a frequency of 1000 Hz to the charging member 56 and supplies an AC current (Iac) of about 1 to 2 mA to the charging member 56. Has been.

  The charging controller 82 includes, for example, an AC current detection unit 86, a discharge charge amount detection unit 88, a DC current detection unit 90, a variation acquisition (calculation) unit 92, a change amount acquisition unit 94, an inflection point specifying unit 96, a target AC current. A value calculation unit 98, a target discharge charge amount definition unit 100, a comparison determination unit 102, and an alternating current amount control unit 104 are included, and constitute a part of the control unit 72.

  The AC current detector 86 detects an AC current (Iac) supplied from the AC power supply 85 to the charging member 56 and outputs the detection result to the discharge charge amount detector 88 and the variation acquisition unit 92.

The discharge charge amount detection unit 88 receives the AC current (detection current) detected by the AC current detection unit 86 and, as shown in FIG. 4, a detected current accompanied by distortion due to discharge and a sine wave (reference sine wave) without distortion. And the difference (actual discharge current) are integrated over time to detect the + and − side discharge charge amounts Q, respectively, and the detection results are output to the target discharge charge amount definition unit 100 and the comparison determination unit 102. For example, the discharge charge amount detection unit 88 detects the discharge charge amount for each period of the alternating current, and sets the average value as the discharge charge amount with respect to the alternating current value.
The discharge charge amount detection unit 88 may be configured to integrate by an analog circuit using a low-pass filter or an integration circuit, or may be integrated using a digital circuit (CPU 74 or the like) after A / D conversion. May be configured.

  FIG. 5 is a graph showing the variation of the discharge charge amount detected by the discharge charge amount detection unit 88 with respect to Iac. As shown in FIG. 5, for example, even when Iac is changed from 1 mA to 1.4 mA, the discharge charge amounts on the + side and − side detected by the discharge charge amount detection unit 88 for each period are small in variation. It has become.

  The direct current detection unit 90 (FIG. 3) detects the direct current (Idc) supplied from the direct current power source 84 to the charging member 56 and outputs the detection result to the variation acquisition unit 92. The Idc is sampled 1000 to 2000 times in the rotation cycle of the charging member 56, for example.

  The variation acquisition unit 92 receives the Iac output from the AC current detection unit 86 and the Idc output from the DC current detection unit 90, acquires (calculates) the variation of Idc with respect to Iac, and averages the variation for each Iac. And the calculated average value is output to the variation acquisition unit 94 as a variation with respect to Iac. For example, the variation acquisition unit 92 is configured as a program executed by the CPU 74, and acquires Idc standard deviation, variance, or a difference between the maximum value and the minimum value as variations.

  The change amount acquisition unit 94 acquires the change amount (slope) with respect to the change of Iac for the variation of Idc input from the variation acquisition unit 92, and outputs the acquisition result to the inflection point specifying unit 96. For example, the change amount acquisition unit 94 is configured as a program executed by the CPU 74.

  The inflection point specifying unit 96 accepts the change amount output from the change amount acquisition unit 94, and the change amount (slope) of Idc variation reaches a saturated state (or less than a predetermined value) as Iac increases. Is specified as an inflection point, and the specified result is output to the target alternating current value calculation unit 98. For example, the inflection point specifying unit 96 is configured as a program executed by the CPU 74.

  The target AC current value calculation unit 98 calculates an AC current value corresponding to the inflection point input from the inflection point specifying unit 96 as a target AC current value, and the calculation result is output to the target discharge charge amount definition unit 100. Output. For example, the target alternating current value calculation unit 98 is configured as a program executed by the CPU 74.

  FIG. 6 is a graph illustrating the average value of Idc variation calculated for each Iac by the variation acquisition unit 92 and the inflection point identified by the inflection point identifying unit 96. As shown in FIG. 6, the inflection point specifying unit 96 specifies, for example, a point where the average value of Idc variation calculated by the variation acquiring unit 92 is saturated (Idc variation = 0.22) as the inflection point of Idc variation. To do. Then, the target alternating current value calculation unit 98 calculates a target alternating current value (Iac = 1.25 mA) corresponding to the inflection point of Idc variation.

  The target discharge charge amount definition unit 100 (FIG. 3) receives the detection result (discharge charge amount) of the discharge charge amount detection unit 88 and the calculation result (target AC current value) of the target AC current value calculation unit 98, respectively. The + and − side discharge charge amounts corresponding to the AC current value are defined as target discharge charge amounts (control targets), and the defined target discharge charge amounts are output to the comparison determination unit 102. For example, the target discharge charge amount defining unit 100 is configured as a program executed by the CPU 74. Further, the target discharge charge amount defining unit 100 stores at least one of the defined target discharge charge amounts in, for example, the memory 76 (see FIG. 2), and the target discharge charge amount is stored in the comparison determination unit 102 via the memory 76. However, it may be configured to output. Further, the target discharge charge amount defining unit 100 may receive the inflection point specifying result from the inflection point specifying unit 96 and define the discharge charge amount corresponding to the inflection point as the target discharge charge amount. Good.

  FIG. 7 is a graph illustrating target discharge charge amounts (control targets) on the + side and − side defined by the target discharge charge amount definition unit 100. As shown in FIG. 7, the target discharge charge amount defining unit 100 includes, for example, a + side discharge charge amount (= 4 μC) corresponding to the target AC current value (Iac = 1.25 mA) calculated by the target AC current value calculation unit 98. / S) and − side discharge charge amount (= −42 μC / s) are defined as target discharge charge amounts (control targets), respectively, and output to the comparison determination unit 102.

The comparison determination unit 102 (FIG. 3) receives the target discharge charge amount output from the target discharge charge amount definition unit 100 and the discharge charge amount output from the discharge charge amount detection unit 88, respectively. The discharge charge amount to be output and the target discharge charge amount are compared in absolute value, and the comparison result is output to the alternating current amount control unit 104. Here, for example, the comparison / determination unit 102 determines “| discharge charge amount | = | target discharge charge amount |”, “| discharge charge amount |> | target discharge charge amount |” or “| discharge charge amount | <| target discharge”. One of the charge amounts | "is output as a comparison result.
The comparison / determination unit 102 may be configured as a program executed by the CPU 74 or may be configured as an analog circuit using a comparator or the like.

The AC current amount control unit 104 sets the high-voltage power supply unit 80 so that the comparison result of the comparison determination unit 102 approaches | discharge charge amount | = | target discharge charge amount | according to the comparison result input from the comparison determination unit 102. And the AC current (Iac) output from the AC power supply 85 is adjusted.
The AC current amount control unit 104 is configured as a program executed by the CPU 74. In order to initially define the target discharge charge amount, the AC current output from the AC power supply 85 is increased within a predetermined range, and the target After the discharge charge amount is defined, the AC current output from the AC power supply 85 is adjusted according to the determination result of the comparison / determination unit 102.

Next, a process in which the charging control device 82 adjusts the alternating current output from the high voltage power supply unit 80 will be described.
FIG. 8 is a flowchart showing an operation (S10) performed by the charging control device 82 in order to adjust the alternating current output from the high-voltage power supply unit 80 to an optimum value.
FIG. 9 is a flowchart showing details of the adjustment process (S20) of the alternating current (Iac) shown in FIG.
As shown in FIG. 8, in step 100 (S100), the charging control device 82 increases (or decreases) Iac from about 1 mA to about 1.4 mA, for example, when the power is turned on. The charge amount and Idc are detected.

  In step 102 (S102), the variation acquisition unit 92 acquires the variation of Idc relative to Iac.

  In step 104 (S104), the change amount acquisition unit 94 acquires a change amount (slope) of Idc variation with respect to a change in Iac.

  In step 106 (S106), the inflection point specifying unit 96 specifies the inflection point of Idc variation.

  In step 108 (S108), the target alternating current value calculation unit 98 calculates Iac (target alternating current value) at the inflection point.

  In step 110 (S110), the target discharge charge amount definition unit 100 defines (stores) the discharge charge amount corresponding to Iac calculated by the target alternating current value calculation unit 98 as the target discharge charge amount, and proceeds to the process of S20. .

  In step 200 (S200: FIG. 9), the alternating current amount control unit 104 increases Iac output from the high voltage power supply unit 80 to such an extent that it does not affect the quality of the image formed on the paper. For example, the AC current amount control unit 104 can increase Iac from 1 mA to about 2 mA in units of about 0.03 mA.

  In step 202 (S202), the discharge charge amount detection unit 88 detects the discharge charge amount via the alternating current detection unit 86.

  In step 204 (S204), the comparison determination unit 102 compares the target discharge charge amount defined by the target discharge charge amount definition unit 100 with the discharge charge amount input from the discharge charge amount detection unit 88 with an absolute value, If the absolute value of the discharge charge amount is smaller than the absolute value of the target discharge charge amount, the process proceeds to S200. If the absolute value of the discharge charge amount is larger than the absolute value of the target discharge charge amount, the process proceeds to S206. If the absolute value of the discharge charge amount is the same as the absolute value of the target discharge charge amount (including the case where the absolute value of the discharge charge amount is substantially the same with a predetermined allowable range), the process proceeds to S212.

  In step 206 (S206), the alternating current amount control unit 104 reduces Iac output from the high voltage power supply unit 80 to the extent that it does not affect the quality of the image formed on the paper. For example, the alternating current amount control unit 104 decreases Iac in units of about −0.03 mA.

  In step 208 (S208), the discharge charge amount detection unit 88 detects the discharge charge amount via the alternating current detection unit 86.

  In step 210 (S210), the comparison determination unit 102 compares the target discharge charge amount defined by the target discharge charge amount definition unit 98 with the discharge charge amount input from the discharge charge amount detection unit 88 with an absolute value, If the absolute value of the discharge charge amount is smaller than the absolute value of the target discharge charge amount, the process proceeds to S200. If the absolute value of the discharge charge amount is larger than the absolute value of the target discharge charge amount, the process proceeds to S206. If the absolute value of the discharge charge amount is the same as the absolute value of the target discharge charge amount (including the case where the absolute value of the discharge charge amount is substantially the same with a predetermined allowable range), the process proceeds to S212.

  In step 212 (S212), the charging control device 82 sets Iac at which the absolute value of the discharge charge amount is the same as the absolute value of the target discharge charge amount as Iac to be output by the AC power supply 85, and sets the set Iac. The high voltage power supply unit 80 is adjusted so that the AC power supply 85 outputs.

FIG. 10 is a graph showing an example of the target discharge charge amount (target value) defined by the target discharge charge amount definition unit 100 (FIG. 3) when the temperature (environment) changes.
When the temperature changes from, for example, 13 ° C. to 18 ° C. due to the operation of the image forming apparatus 10, the discharge charge amount Q detected by the discharge charge amount detection unit 88 and the variation acquisition unit 92, as shown in FIG. The Idc variation obtained by each indicates a value shifted substantially in the direction of decreasing Iac while maintaining the tendency at 13 ° C.

  Here, even if the target AC current value calculated by the target AC current value calculation unit 98 changes due to the temperature change, the target discharge charge amount (target value) defined by the target discharge charge amount definition unit 100 changes. do not do. Therefore, the charge control device 82 sets the discharge charge amount detected by the discharge charge amount detection unit 88 to the target discharge charge amount without defining the target discharge charge amount again even if the temperature or humidity changes in a short time. By making it approach, the magnitude | size of Iac which the high voltage electric power feeding part 80 outputs can be brought close to a target alternating current value.

  In the above-described embodiment, the image forming apparatus 10 having one charging member 56 for charging one image holding body 44 has been described. However, the present invention is not limited to this, and for example, a color having four image holding bodies. In the image forming apparatus, the alternating current may be controlled by adjusting the discharge charge amount for the four charging devices that charge the image carrier.

  A program executed by the control unit 72 to perform control may be provided via the communication device 70 or may be provided by being stored in a storage medium such as a CD-ROM.

1 is a side view illustrating an outline of an image forming apparatus according to an embodiment of the present invention. 1 is a configuration diagram illustrating an overview of an image forming apparatus according to an embodiment of the present invention. It is a block diagram which shows the detail of a high voltage electric power feeding part, a charging control apparatus, and its periphery. It is a graph which shows discharge charge amount as a result of integrating the difference of a detection electric current and a reference sine wave. It is a graph which shows the dispersion | variation with respect to Iac of the discharge charge amount which the discharge charge amount detection part detected. 5 is a graph illustrating an average value of Idc variation calculated for each Iac by a variation acquisition unit and an inflection point identified by an inflection point identifying unit. It is a graph which illustrates the target discharge charge amount (control target) of + side and-side which the target discharge charge amount definition part defined. It is a flowchart which shows the operation | movement (S10) which a charging control apparatus performs in order to adjust the alternating current which a high voltage electric power feeding part outputs to an optimal value. It is a flowchart which shows the detail of the adjustment process (S20) of alternating current (Iac) shown in FIG. It is a graph which shows the Example of the target discharge charge amount (target value) which a target discharge charge amount definition part defines, when temperature (environment) changes.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 44 Image holding body 56 Charging member 72 Control unit 74 CPU
76 Memory 80 High Voltage Power Supply Unit 82 Charging Control Device 84 DC Power Supply 85 AC Power Supply 86 AC Current Detection Unit 88 Discharge Charge Amount Detection Unit 90 DC Current Detection Unit 92 Variation Acquisition Unit 94 Change Amount Acquisition Unit 96 Inflection Point Identification Unit 98 Target AC Current value calculation unit 100 Target discharge charge amount definition unit 102 Comparison determination unit 104 AC current amount control unit

Claims (10)

A discharge charge amount detecting means for detecting a charge amount of a discharge generated in accordance with an alternating current supplied to a charging member for charging a member to be charged;
DC current detection means for detecting DC current supplied to the charging member;
Variation obtaining means for obtaining the variation of the direct current detected by the direct current detecting means in correspondence with the alternating current value;
A change amount acquisition means for acquiring a change amount with respect to a change in alternating current with respect to the variation acquired by the variation acquisition means;
Target value defining means for defining a target value of the charge amount detected by the discharge charge amount detecting means in accordance with the change amount acquired by the change amount acquiring means;
AC current adjusting means for adjusting the AC current supplied to the charging member according to the target value defined by the target value defining means and the charge amount detected by the discharge charge amount detecting means;
A charge control device.   The target value defining means determines the amount of charge detected by the discharge charge amount detecting means when the amount of change acquired by the change amount acquiring means reaches a saturated state or a predetermined value or less as the alternating current increases. The charge control device according to claim 1, wherein the charge control device is defined as a target value. The charge control device according to claim 1, wherein the variation acquisition unit acquires a standard deviation, a variance, or a difference between a maximum value and a minimum value of a direct current as a variation corresponding to the alternating current value . A charging member for charging the object to be charged;
A discharge charge amount detecting means for detecting a charge amount of discharge generated according to an alternating current supplied to the charging member;
DC current detection means for detecting DC current supplied to the charging member;
Variation obtaining means for obtaining the variation of the direct current detected by the direct current detecting means in correspondence with the alternating current value;
A change amount acquisition means for acquiring a change amount with respect to a change in alternating current with respect to the variation acquired by the variation acquisition means;
Target value defining means for defining a target value of the charge amount detected by the discharge charge amount detecting means in accordance with the change amount acquired by the change amount acquiring means;
AC current adjusting means for adjusting the AC current supplied to the charging member according to the target value defined by the target value defining means and the charge amount detected by the discharge charge amount detecting means;
A charging device.   The target value defining means determines the amount of charge detected by the discharge charge amount detecting means when the amount of change acquired by the change amount acquiring means reaches a saturated state or a predetermined value or less as the alternating current increases. The charging device according to claim 4, wherein the charging device is defined as a target value. 6. The charging device according to claim 4, wherein the variation obtaining unit obtains the standard deviation of the direct current, the dispersion, or the difference between the maximum value and the minimum value as variations corresponding to the alternating current value . An image carrier,
A charging member for charging the image carrier;
Power supply means for supplying a current obtained by superimposing a direct current and an alternating current to the charging member;
A discharge charge amount detection means for detecting a charge amount of discharge generated in response to an alternating current supplied to the charging member by the power supply means;
DC current detecting means for detecting a DC current supplied to the charging member;
Variation obtaining means for obtaining the variation of the direct current detected by the direct current detecting means in correspondence with the alternating current value;
A change amount acquisition means for acquiring a change amount with respect to a change in alternating current with respect to the variation acquired by the variation acquisition means;
Target value defining means for defining a target value of the charge amount detected by the discharge charge amount detecting means in accordance with the change amount acquired by the change amount acquiring means;
AC current adjusting means for adjusting the AC current supplied to the charging member according to the target value defined by the target value defining means and the charge amount detected by the discharge charge amount detecting means;
An image forming apparatus.   The target value defining means determines the amount of charge detected by the discharge charge amount detecting means when the amount of change acquired by the change amount acquiring means reaches a saturated state or a predetermined value or less as the alternating current increases. The charging device according to claim 4, wherein the charging device is defined as a target value. 9. The image forming apparatus according to claim 7, wherein the variation obtaining unit obtains the standard deviation of the direct current, the dispersion, or the difference between the maximum value and the minimum value as variations corresponding to the alternating current value . Detecting a discharge charge amount generated in response to an alternating current supplied to a charging member for charging a member to be charged;
Detecting a direct current supplied to the charging member;
Obtaining a variation in the detected direct current corresponding to the alternating current value;
Obtaining a variation amount of the variation with respect to a change in alternating current;
A step of defining a scale of discharge charge amount according to the obtained change amount;
Adjusting the alternating current supplied to the charging member according to the defined target value and the amount of discharge charge to be detected;
A charge control program that causes a computer to execute.

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