JP2007183475A - Charging device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately detect the thickness of the layer of a photoreceptor by accurately detecting variation in the charging amount. <P>SOLUTION: A charging current detection part 84 detects a current (charging current) obtained by superposing an AC component and a DC component supplied from a DC power supply 78 and an AC power supply 80 and outputs the detected current to an LPF 86. The LPF 86 removes the AC component of the current and outputs the current. An A/D conversion part 88 converts an analog current value input from the LPF 86 into a digital value in accordance with a sampling clock input from a processing control part 90, and outputs the digital value to the processing control part 90. The processing control part 90 includes a CPU and a memory which are not illustrated, has an integrating processing part 92 and a layer thickness calculation part 94 which are programs performed by the CPU, integrates the value input from the A/D conversion part 88, calculates the layer thickness of a photoreceptive layer 74 by using the result of integration, and outputs the obtained result to a UI device 70 or the like. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charging device and an image forming apparatus for charging an object to be charged.

  In an image forming apparatus having a photosensitive member that is charged and carries a toner image, the charged layer formed on the surface of the photosensitive member is worn by contact of, for example, a charging roll, a developing roll, and a cleaning blade. In this type of image forming apparatus, there is a problem that the image quality of the output image is deteriorated when the charged layer of the photoreceptor is worn. In order to solve this problem, the voltage applied to the charging roller for charging the photoconductor and the charging current are measured, and the thickness of the photoconductor layer is calculated based on the fact that the charging current is proportional to the process speed. It is known to prevent the occurrence of defects (see Patent Document 1).

Japanese Patent No. 3064643

  However, in the above conventional example, since the charging current to be detected depends on the rotational speed of the photoconductor, the thickness of the layer of the photoconductor cannot be detected with high accuracy, and fluctuations in the charge amount can be detected with high accuracy. There is a problem that the photosensitive member cannot be charged.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a charging device and an image forming apparatus that can detect the variation in the charge amount with high accuracy and detect the thickness of the layer of the photoconductor with high accuracy.

  In order to achieve the above object, the first feature of the present invention is that a charging device body is provided with a charging layer on the surface and charges a member to be rotated, and a direct current component and Power supply means for supplying a current having an AC component, detection means for detecting a value corresponding to the current output from the power supply means, a low-pass filter for smoothing the value detected by the detection means, and the low-pass filter The charging device includes an integrating unit that samples and integrates the converted values, and a layer thickness calculating unit that calculates a numerical value related to the thickness of the charging layer based on the values integrated by the integrating unit. In other words, since the low-pass filter removes the AC component of the current supplied by the power supply means, it is possible to prevent the values sampled by the integrating means from varying, and to accurately calculate the numerical value related to the thickness of the charging layer. Can do. Therefore, it is possible to charge the object to be charged by accurately detecting fluctuations in the charge amount.

  Preferably, the low-pass filter has a time constant not less than the sampling period of the integrating means and not more than one third of the rotation period of the charged body. That is, the integration means can sample the value smoothed by the low-pass filter at least three times until the value corresponding to the current output from the power supply means reaches a peak from 0. Therefore, it is possible to charge the object to be charged by accurately detecting fluctuations in the charge amount.

  Preferably, a timer for controlling the timing of the signal is further provided, and the integrating means performs sampling according to the timing controlled by the timer.

  Further, the second feature of the present invention is that a charging device main body that is provided with a charging layer on its surface and charges a rotationally driven member to be charged, and a power supply means for supplying current to the charging device main body, Detection means for detecting a value corresponding to the current output from the power supply means, A / D conversion means for sampling the value detected by the detection means and performing A / D conversion, and the A / D conversion means include A / D conversion means Integration means for integrating the D-converted values, layer thickness calculation means for calculating a numerical value related to the thickness of the charged layer based on the values integrated by the integration means, and conversion criteria for the A / D conversion means In a charging device having control means for controlling in accordance with the rotational speed of the member to be charged.

  Preferably, the A / D conversion means has a constant number of samplings with respect to the rotation period of the charged body.

  The third feature of the present invention is that a charging device body is provided with a charging layer on its surface and charges a member to be rotated, and a power supply means for supplying current to the charging device body. Detection means for detecting a value corresponding to the current output from the power supply means, A / D conversion means for sampling the value detected by the detection means and performing A / D conversion, and the A / D conversion means include A / D conversion means Integration means for integrating the D-converted value, layer thickness calculation means for calculating a numerical value related to the thickness of the charged layer based on the value integrated by the integration means, and the number of samples of the A / D conversion means In a charging device having control means for controlling in accordance with the rotational speed of the member to be charged.

  A fourth feature of the present invention resides in an image forming apparatus having the above charging device.

  According to the present invention, it is possible to detect the variation in the charge amount with high accuracy and to detect the thickness of the layer of the photoconductor with high accuracy.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows 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 part near the rear end of the paper feed cassette 22, and a retard roll 26 and a nudger 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 carrier 44 described later are disposed on the upstream side of the fixing device 36 in the conveyance path 32, and a resist roll 38 is disposed on the upstream side of the transfer device 42 and the image carrier 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 18a to 18d by the feed roll 24 is wound by the retard roll 26 and the nudger 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 is discharged by a discharge roll 40. 34 is discharged 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 conveyance 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 portion 16 through the registration roll 38, the transfer device 42, the image carrier 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 carrier 44 made of a photoconductor, a charging roll 56 that uniformly charges the image carrier 44 by pressure contact, and an image charged by the charging roll 56. An optical writing device 58 that writes a latent image on the carrier 44 with light, a developing device 60 that visualizes the latent image of the image carrier 44 formed by the optical writing device 58 with a developer, and development by the developing device 60 A transfer device 42 made of, for example, a transfer roll for transferring the agent image to the paper, a cleaning device 62 made of, for example, a blade for cleaning the developer remaining on the image carrier 44, and a developer on the paper 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 an image on a sheet. 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 above-described paper feeding units 18a to 18d. 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 roll 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 process cartridge 64 is detachably divided into an image carrier charging unit 66 in which the image carrier 44, the charging roll 56 and the cleaning device 62 are arranged, and a developing device unit 68 in which the developing device 60 is arranged. .

  In addition, a user interface (UI) device 70 such as a touch panel is provided on the outer surface of the image forming apparatus main body 12. The UI device 70 accepts an input such as an instruction from a user and displays a processing result of the image forming apparatus 10 and the like.

FIG. 2 shows details of the image carrier 44, the charging roll 56, and the periphery thereof.
The image carrier 44 includes a cylindrical drum 72 and a photosensitive layer 74 formed on the outer surface of the drum 72. The drum 72 is made of a conductor such as aluminum and is grounded. The photosensitive layer 74 is composed of an inorganic or organic photoconductor, and is a charged layer that is charged by charges supplied from the charging roll 56.

  Further, in the vicinity of the image carrier 44, a static elimination lamp 76 that neutralizes the charge remaining on the photosensitive layer 74 after the image carrier 44 transfers the developer image is disposed. For example, every time the image carrier 44 rotates once, the charge removal lamp 76 removes the charge remaining on the photosensitive layer 74 once. In addition, the charge removal lamp 76 may perform charge removal at other timing.

The charging roll 56 charges the image carrier 44 with current supplied from each of the DC power supply 78 and the AC power supply 80. That is, the charging roll 56 is charged by a current in which an AC component and a DC component are superimposed.
Between the AC power supply 80 and the ground, an AC current detection unit 82 for measuring a current output from the AC power supply 80 is provided.

  The charging current detector 84 detects the current (charging current) on which the AC component and the DC component supplied from the DC power supply 78 and the AC power supply 80 are superimposed, and outputs the detected current to the low-pass filter (LPF) 86. Note that the charging current detector 84 may output a voltage value corresponding to the charging current.

  The LPF 86 has a time constant τ to be described later. By filtering the current (or voltage, etc.) input from the charging current detector 84 with the time constant τ, the AC component of the current is removed and smoothed. The current value is output to the A / D converter 88. The A / D converter 88 includes, for example, an A / D converter (not shown) having an 8-bit resolution, and an analog current value input from the LPF 86 is converted according to a sampling clock input from the processing controller 90. The digital value is converted and output to the processing control unit 90.

  The processing control unit 90 includes a CPU and a memory (not shown), has an integration processing unit 92 and a layer thickness calculation unit 94 that are programs executed by the CPU, and uses values input from the A / D conversion unit 88. The layer thickness of the photosensitive layer 74 is calculated and output to the UI device 70 or the like. In addition, the processing control unit 90 outputs a sampling clock to the A / D conversion unit 88 according to timing controlled by a timer (not shown) of the CPU (described later with reference to FIG. 6), and configures the image forming apparatus 10. Control each part.

  For example, the integration processing unit 92 receives the value output from the A / D conversion unit 88 when charging is performed multiple times until the charging potential is sufficiently converged by turning off the static elimination lamp 76, and integrates it for a predetermined time. (For example, current integrated value: ΣI = charged charge amount) is output to the layer thickness calculator 94.

  The layer thickness calculation unit 94 receives the integration result output from the integration processing unit 92, calculates the layer thickness d of the photosensitive layer 74 by the following equation 1, and outputs the calculation result to the UI device 70 or the like.

d = ε · ε0 · l · D · π · V / ΣI (1)
ε: dielectric constant of photosensitive layer 74
ε0: Dielectric constant of vacuum
l: Effective charging length of the image carrier 44
D: Diameter of the photosensitive layer 74 (≈outer diameter of the drum 72)
V: Applied voltage of DC power supply 78
ΣI: Integrated current value (charged charge amount)

Next, the relationship between the integration processing unit 92 integrating the current value and the time constant τ of the LPF 86 will be described in detail.
FIG. 3 is a graph showing the timing at which the A / D conversion unit 88 samples the charging current smoothed by the LPF 86 and the charging current (charged charge amount) integrated by the integration processing unit 92.
FIG. 4 is a graph showing the relationship between the timing at which the A / D converter 88 samples the charging current smoothed by the LPF 86 and the time constant τ of the LPF 86.
As shown in FIGS. 3 and 4, since the sampling period Ts is set to be equal to or less than the time constant τ of the LPF 86, the A / D converter 88 has a charging current smoothed by the LPF 86 from 0 to a peak value Ia of 95. Sample at least three transients until% is reached. That is, the integration processing unit 92 integrates the values sampled three or more times by the A / D conversion unit 88 until the charging current from which the LPF 86 has removed the AC component reaches 95% of the peak value Ia from 0. It is possible to calculate a charge amount with a small integration error with respect to the charging current output by.

FIG. 5 is a graph showing the charging current (charged charge amount) integrated by the integration processing unit 92 in accordance with the relationship between the rotation cycle of the image carrier 44 and the time constant τ of the LPF 86.
As shown in FIG. 5, the image carrier 44 has a rotation period T1 set to 3τ or more, and when the charge removing lamp 76 is turned off and charged, the charging current supplied to the image carrier 44 in the first round reaches its peak. The supply of the charging current is stopped after reaching the value Ia, and the actual charge amount of the photosensitive layer 74 becomes Ia × T1, whereas the integral value of the charge amount calculated by the integration processing unit 92 is approximately Ia × T1. It is supposed to be.

As a comparative example, when the rotation period T2 of the image carrier 44 is less than 3τ, the rotation period T2 of the image carrier 44 is assumed to be the same as the time constant τ of the LPF 86, for example, as shown by the thick broken line in FIG. Then, the integrated value of the charge amount calculated by the integration processing unit 92 is approximately 0.632 Ia × T2, and the integration error of the integration processing unit 92 with respect to the set peak value Ia of the charging current becomes large.
Therefore, the rotation period of the image carrier 44 is set to 3τ or more so that the integration error of the charge amount calculated by the integration processing unit 92 is 5% or less.

  For example, in the image forming apparatus 10, the LPF 86 has a time constant τ set to 10 mS (3τ = 30 mS), a cutoff frequency set to 16 Hz, and the frequency of the AC current output from the AC power supply 80 is set to about 1 KHz. When the attenuation ratio is about 80 db, the alternating current component of the charging current is attenuated, for example, from about 2 mA to about 0.2 μA. When the static elimination lamp 76 is turned off and the rotation of the image carrier 44 is in the first round, for example, the DC component of the charging current is several tens of μA, and the attenuated AC component is 1% of the DC component. Thus, the error due to the AC component with respect to the integration result of the integration processing unit 92 can be ignored.

Further, in a normal image forming apparatus, the rotation period of the image carrier 44 is at least about several hundreds mS, and when the time constant τ of the LPF 86 is set to 10 mS, the charging current is supplied during the first rotation of the image carrier 44. Sufficiently reaches the peak value Ia. Therefore, the image forming apparatus 10 can reduce the integration error of the charge amount calculated by the integration processing unit 92 to 5% or less even when the A / D conversion unit 88 performs sampling in response to a signal whose cycle is 10 mS. it can.
However, the A / D conversion unit 88 is configured to sample the charging current in accordance with a timing triggered by a signal controlled by a CPU timer (not shown) of the processing control unit 90.

FIG. 6 is a comparison diagram showing the timing at which the A / D converter 88 samples in a predetermined cycle. FIG. 6A shows an ideal sampling trigger, and FIG. 6B shows the A / D converter 88. The sampling timing which can be set is shown, and (C) is a comparison diagram showing the sampling timing according to the signal indicating the task end as a comparative example.
As shown in FIG. 6, when the number of times that the A / D conversion unit 88 samples in a predetermined cycle is ideally seven, the A / D conversion unit 88 is a CPU timer (not shown) of the processing control unit 90. The charging current is sampled by using a signal controlled by, and the accumulated error of the sampling timing can be set to be within one cycle of the trigger signal. As a comparative example, as shown in FIG. 6C, when the A / D converter 88 performs sampling in accordance with a signal indicating task end, if the end timing of tasks processed in parallel fluctuates, a timing error may occur. For example, the number of times of sampling in a predetermined period is nine.
Therefore, the A / D conversion unit 88 is configured to sample the charging current using a signal controlled by a CPU timer (not shown) of the processing control unit 90 or a signal output from the oscillator as a trigger.

Next, another configuration example of the image carrier 44, the charging roll 56, and the periphery thereof in the image forming apparatus 10 will be described.
FIG. 7 is a block diagram illustrating a modification of the configuration of the image carrier 44, the charging roll 56, and the periphery thereof in the image forming apparatus 10.
As shown in FIG. 7, the image forming apparatus 10 detects that the detection result of the charging current detection unit 84 is a UI device via the A / D conversion unit 96, the reference voltage control circuit 98, the sampling clock control circuit 100, and the processing control unit 102. It may be configured to output to 70 or the like.
In the configuration shown in FIG. 7, the same components as those shown in FIG. 2 are denoted by the same reference numerals.

  The A / D conversion unit 96 sets a conversion reference (dynamic range) according to the reference voltage set by the reference voltage control circuit 98, and an analog value corresponding to the charging current value input from the charging current detection unit 84 is It is converted into a digital value in accordance with the sampling clock input from the sampling clock control circuit 100 and output to the processing control unit 102.

The reference voltage control circuit 98 controls the reference voltage value of the A / D conversion unit 96 according to the rotation speed data of the image carrier 44 input from the processing control unit 102.
The sampling clock control circuit 100 controls and outputs a sampling clock for the A / D conversion unit 96 according to the rotation speed data of the image carrier 44 input from the processing control unit 102.

  The processing control unit 102 includes a CPU and a memory (not shown), has an integration processing unit 92 and a layer thickness calculation unit 94 that are programs executed by the CPU, and uses values input from the A / D conversion unit 96. The layer thickness of the photosensitive layer 74 is calculated and output to the UI device 70 or the like. The processing control unit 102 controls each part of the image forming apparatus 10 and outputs rotation speed data of the image carrier 44 to the sampling clock control circuit 100 and the reference voltage control circuit 98.

  Note that an LPF 86 may be inserted between the charging current detection unit 84 and the A / D conversion unit 96.

FIG. 8 is a graph showing fluctuations in the charging current output from the charging current detector 84 and the AC power supply 80 with respect to changes in the rotational speed of the image carrier 44.
As shown in FIG. 8, for example, when the rotation speed (rotation period) of the image carrier 44 is halved, the charging current detector 84 and the AC power supply 80 have a peak value of the charging current to be output of 2 minutes. The charging cycle is set to be doubled. Further, when the layer thickness of the photosensitive layer 74 changes, the charge amount (and the charging current of the charging current) that the photosensitive layer 74 actually charges with respect to the peak value of the charging current set for each rotation speed of the image carrier 44. Peak value) changes.

Next, a first operation example in the modified example of the configuration of the image carrier 44, the charging roll 56, and the periphery thereof shown in FIG. 7 will be described.
FIG. 9 is a graph showing a first operation example in the modification of the configuration of the image carrier 44, the charging roll 56, and the periphery thereof shown in FIG.
As shown in FIG. 9, the reference voltage control circuit 98 processes data indicating that the rotational speed of the image carrier 44 is set to a rotational speed PS2 that is, for example, a half of the predetermined rotational speed PS1. When accepted from the control unit 102, the voltage value Ref11 at the top of the reference voltage for the rotation speed PS1 of the A / D conversion unit 96 is halved, and the voltage value Ref12 at the top of the reference voltage for the rotation speed PS2 is set to A / D. Control is performed so as to set the conversion unit 96. The A / D converter 96 is configured to keep the voltage value Ref2 at the bottom of the reference voltage constant, for example.
As described above, the reference voltage control circuit 98 changes the conversion reference of the A / D conversion unit 96 in accordance with the change in the peak value of the charging current detected by the charging current detection unit 84.

Further, the sampling clock control circuit 100 accepts data indicating that the rotation speed of the image carrier 44 is set to, for example, a rotation speed PS2 that is a half of the predetermined rotation speed PS1 from the processing control unit 102. Then, the sampling cycle Ts1 for the rotation speed PS1 of the A / D conversion unit 96 is doubled, and the sampling cycle Ts2 for the rotation speed PS2 is controlled to be the sampling clock cycle for the A / D conversion unit 96.
That is, the sampling clock control circuit 100 controls the period of the sampling clock so that the number of samplings during one rotation of the image carrier 44 does not change even if the rotation speed of the image carrier 44 changes.

  Therefore, the processing control unit 102 can calculate the layer thickness of the photosensitive layer 74 by using the value input from the A / D conversion unit 96 without correcting it according to the rotation speed of the image carrier 44.

Next, a second operation example in the modification of the configuration of the image carrier 44, the charging roll 56, and the periphery thereof shown in FIG. 7 will be described.
FIG. 10 is a graph showing a second operation example in the modification of the configuration of the image carrier 44, the charging roll 56, and the periphery thereof shown in FIG.
As shown in FIG. 10, the reference voltage control circuit 98 processes data indicating that the rotation speed of the image carrier 44 is set to, for example, a rotation speed PS2 that is a half of the predetermined rotation speed PS1. Even if received from the control unit 102, the top voltage value Ref11 and the bottom voltage value Ref2 of the reference voltage with respect to the rotation speed PS1 of the A / D conversion unit 96 are not changed.

Further, the sampling clock control circuit 100 accepts data indicating that the rotation speed of the image carrier 44 is set to, for example, a rotation speed PS2 that is a half of the predetermined rotation speed PS1 from the processing control unit 102. However, the sampling period Ts1 for the rotational speed PS1 of the A / D converter 96 is not changed.
That is, the sampling clock control circuit 100 sets the sampling clock cycle so that the number of samplings changes during one rotation of the image carrier 44 according to the rotation speed of the image carrier 44, and performs A / D conversion. The SN of the data sampled by the unit 96 is improved.

  Therefore, the processing control unit 102 can calculate the layer thickness of the photosensitive layer 74 by using the value input from the A / D conversion unit 96 without correcting it according to the rotation speed of the image carrier 44.

  In the above embodiment, the case where the image forming apparatus 10 calculates the thickness of the photosensitive layer 74 has been described as an example. However, the image forming apparatus 10 is not limited to this, and the thickness of the photosensitive layer 74 is, for example, Other numerical values related to the thickness of the photosensitive layer 74, such as the rate of change in thickness, may be calculated.

1 is a side view showing an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a block diagram illustrating details of an image carrier, a charging roll, and the periphery thereof. It is a graph which shows the timing which the A / D conversion part samples the charging current smoothed by the LPF, and the charging current (charged charge amount) integrated by the integration processing part. It is a graph which shows the relationship between the timing which an A / D conversion part samples the charging current which LPF smoothed, and the time constant (tau) of LPF. 6 is a graph showing charging current (charged charge amount) integrated by an integration processing unit in accordance with the relationship between the rotation period of the image carrier and the time constant τ of the LPF. It is a comparison figure which shows the timing which an A / D conversion part samples in a predetermined period. FIG. 6 is a block diagram illustrating a modification of the configuration of the image carrier, the charging roll, and the periphery of the image forming apparatus. It is a graph which shows the fluctuation | variation of the charging current which a charging current detection part and alternating current power supply output with respect to the change of the rotational speed of an image carrier. It is a graph which shows the 1st operation example in the modification of a structure of the image carrier shown in FIG. 7, a charging roll, and its periphery. It is a graph which shows the 2nd operation example in the modification of a structure of the image carrier shown in FIG. 7, a charging roll, and its periphery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 14 Image forming means 44 Image carrier 56 Charging roll 70 UI apparatus 72 Drum 74 Photosensitive layer 76 Static elimination lamp 78 DC power supply 80 AC power supply 84 Charging current detection part 86 LPF
88 A / D conversion unit 90 Processing control unit 92 Integration processing unit 94 Layer thickness calculation unit 96 A / D conversion unit 98 Reference voltage control circuit 100 Sampling clock control circuit 102 Processing control unit

Claims (7)

  A charging device main body which is provided with a charging layer on the surface and charges a member to be rotated and driven, a power supply means for supplying a current having a DC component and an AC component to the charging device main body, and a current output by the power supply means Detecting means for detecting a value corresponding to the above, a low pass filter for smoothing the value detected by the detecting means, an integrating means for sampling and integrating the values smoothed by the low pass filter, and the integrating means integrated And a layer thickness calculating means for calculating a numerical value related to the thickness of the charging layer based on the value.   2. The charging device according to claim 1, wherein the low-pass filter has a time constant equal to or greater than a sampling period of the integrating means and equal to or less than one third of a rotation period of the charged body.   3. The charging device according to claim 1, further comprising a timer for controlling a signal timing, wherein the integrating unit performs sampling according to a timing controlled by the timer.   A charging device main body which is provided with a charging layer on the surface and charges the object to be rotated and driven, a power supply means for supplying current to the charging device main body, and a value corresponding to the current output by the power supply means are detected. Detection means, A / D conversion means for sampling and A / D converting values detected by the detection means, integration means for integrating the values A / D converted by the A / D conversion means, and the integration means And a control for controlling the conversion reference of the A / D conversion means in accordance with the rotational speed of the object to be charged, based on the integrated value of the charging layer. And a charging device.   The charging device according to claim 4, wherein the A / D conversion means has a constant sampling number with respect to a rotation cycle of the charged body.   A charging device main body which is provided with a charging layer on the surface and charges the object to be rotated and driven, a power supply means for supplying current to the charging device main body, and a value corresponding to the current output by the power supply means are detected. Detection means, A / D conversion means for sampling and A / D converting values detected by the detection means, integration means for integrating the values A / D converted by the A / D conversion means, and the integration means And a control for controlling the number of samplings of the A / D conversion unit according to the rotational speed of the object to be charged, based on the integrated value of the charging layer. And a charging device.   An image forming apparatus comprising the charging device according to claim 1.

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