JP2003066081A - Charge distribution measuring device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely measure distribution data for charging characteristic and sensitivity characteristic over the whole surface of a photoconductor such as photoreceptor in a short time. SOLUTION: When the surface of a photoreceptor drum 2 is charged to measure the surface potential, a surface potentiometer 5 is moved in the axial direction of the photoreceptor drum 2 in the same direction as the moving direction of charging with a charging unit 3 at the same speed as the moving speed of the charging unit 3, and the surface potential of the charged photoreceptor drum 2 or the charged and exposed photoreceptor drum 2 is measured, whereby the surface potential distribution of the photoreceptor drum 2 can be precisely measured in each position of the photoreceptor drum 2 under the same measuring condition of surface potential.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge distribution measuring apparatus and an image forming apparatus for measuring the charge distribution of a photoconductor such as a photoconductor drum used in a copying machine or a printer for forming an image by electrophotography. It is about.

[0002]

2. Description of the Related Art For example, when manufacturing an organic photosensitive drum used in a copying machine or the like for forming an image by electrophotography,
In order to know non-destructively, non-contact, the condition of the entire surface of the drum, such as coating film defects and film thickness unevenness due to the inclusion of dust during coating, a visual inspection is performed with human eyes, and a CCD line sensor or CCD camera is used. A method of performing inspection by image processing is used. Although this inspection method is good for detecting pinholes and dust that has adhered, information such as whether or not the electrophotographic characteristics required for the photoconductor when it is used in the electrophotographic process, such as whether the charging characteristics differ from place to place, is provided. Can't get In order to measure such electrophotographic characteristics, the entire surface of the photosensitive drum is directly charged by the charging method of the electrophotographic process, the surface potential is measured, and a potential distribution map of the entire surface is created to determine the electrophotographic characteristics. For example, see: Ming-Kay etc. QEA.inc. "Advanced Co
mputer-controlled Instrumentation for Electrophoto
graphy ", Japan Hardcopy '98 P415-420 .1998.

[0003]

However, when a potential distribution map of the entire surface of the photosensitive drum is prepared from the measurement of surface potential, a commercially available surface having a low spatial resolution generally used for measuring electrophotographic characteristics. Since the electrometer has a distance of 2 mm from the measurement target and a detection range of about 10 to 15 mm in diameter, using this surface electrometer, one line of charged potential is repeatedly measured to create a potential distribution map connecting them. However, there is a disadvantage in that it cannot be used for detection of fine defects existing at high density in terms of spatial resolution, that is, defects of electrophotographic characteristics.

Further, a conventional apparatus for obtaining a potential distribution chart from a commercially available surface electrometer is one in which an electrophotographic process is directly implemented, a photosensitive drum is charged, and in some cases, exposed to measure the potential. However, in order to obtain meaningful data for the purpose of detecting various characteristics over the entire surface of the photosensitive drum, it is necessary to devise a measuring device and a measuring method for each purpose. There was no combination of methods.

Further, measuring the potential distribution on the entire surface of the photoconductor drum requires a large amount of data, which requires a lot of time for the measurement itself, and it is necessary to improve the efficiency of the measurement.

Further, as a method for measuring the potential distribution, A
There is also a method of measuring the potential distribution of the device by a measuring method called FM, but this has a spatial resolution of the order of nm, and therefore the size of the measurement sample is limited. Further, the electric potential level applied to the photosensitive drum in the electrophotographic process is 500 V to 1000 V in absolute value,
It is difficult to measure such a potential and it cannot be applied to the measurement of the electrophotographic characteristics of the photosensitive drum.

The present invention solves the above disadvantages, and a charge distribution measuring device and a photoconductor capable of measuring the distribution data of the charging property and the sensitivity property of a photoconductor such as a photoconductor over the entire surface with high accuracy and in a short time. It is an object of the present invention to provide an image forming apparatus capable of increasing the reliability by detecting a change in the charging characteristic of the.

[0008]

A charge distribution measuring apparatus according to the present invention is provided with at least a charging unit and a surface potential around a cylindrical drum mounted on a rotary driving device, in which a film of a photoconductor or an insulator is formed. Place the measuring units individually,
While moving the charging unit in the axial direction of the cylindrical drum by the feeding device, the surface of the cylindrical drum is charged, and the surface potential measuring unit is in the same direction as the charging unit when charging the same as the moving speed of the charging unit. The surface potential at each position of the charged cylindrical drum is measured by moving it in the axial direction of the cylindrical drum at a speed by the same time after charging, and the measurement conditions of the surface potential at each position are measured. The feature is that they are the same.

In a second charge distribution measuring device according to the present invention, a film of a photoconductor or an insulator is formed, and at least a charging unit, an exposure unit, and a surface potential are provided around a cylindrical drum mounted on a rotation driving device. The measurement units are individually arranged, the charging unit moves in the axial direction of the cylindrical drum by the feeding device, and the surface of the cylindrical drum is charged, and the exposure unit moves by the feeding device in the axial direction of the cylindrical drum. Exposing the surface of the charged cylindrical drum while moving at the same speed as
The surface potential of the cylindrical drum that has been charged / exposed by moving in the axial direction of the cylindrical drum by the feeder at the same speed as the moving speed of the charging unit and moving at the same speed as the moving speed of the charging unit is measured and charged.・ Measure the same measurement conditions for the surface potential at each position of the exposed cylindrical drum.

The above units are arranged at an equal angle θ along the circumferential direction of the cylindrical drum, and the angle θ (degree) is 360 / N.
(The number of used units-1), where N is an integer of 2 or more, and when the radius of the cylindrical drum to be measured is r, the operating range in the circumferential direction of the arrangement unit excluding the surface electrometer on the inner cylindrical drum is For the maximum value k, θ · (2πr / 36
0) ≧ k, the cylindrical drum is rotated by an angle θ, and charging and surface potential measurement or charging, exposure, and surface potential measurement are repeated, and when the cylindrical drum rotates once, By rotating the cylindrical body at an arbitrary angle and repeating the above-mentioned operation from the beginning, the influence of charging and exposure due to the previous measurement is removed and the surface potential is accurately measured.

Further, it is preferable that the charging of the cylindrical drum and the measurement of the surface potential are continuously performed to detect a local defect in which a difference between a normal portion and an abnormal portion is apt to become clear immediately after the charging.

Further, in the case where a part of the cylindrical drum is fatigued, the potential decay (dark decay) of the fatigued part progresses as time elapses from the charging, and the difference from the normal part becomes clear and abnormal. Is easier to detect. Therefore, it is advisable to measure the surface potential after a lapse of a certain time after charging the cylindrical drum to clarify the fatigued portion and the state of fatigue.

Another charge distribution measuring apparatus according to the present invention is
The charging unit and the surface potential measuring unit or the charging unit, the exposing unit and the surface potential measuring unit are integrally arranged by arranging them in the axial direction of the cylindrical drum on which the photoconductive or insulating film is formed and which is mounted on the rotation driving device. While moving the measured unit in the axial direction of the cylindrical drum by the feeding device, the surface of the cylindrical drum is charged and exposed, and the surface potential is measured, and the measurement conditions of the surface potential at each position of the cylindrical drum are made the same. .

It is desirable that a plurality of sets of the above-mentioned measuring units are arranged at equal angles along the outer circumference of the cylindrical drum to enhance the measurement efficiency of the surface potential.

Furthermore, when the surface potential of the cylindrical drum is measured and then the charge is removed from the cylindrical drum, and the surface potential is subsequently measured, it is possible to accurately measure the surface potential by removing the influence of the previous charging. desirable.

Further, the photoconductor drum is used as the cylindrical drum, and the image forming apparatus is provided with a charge distribution measuring device for measuring the surface potential after a lapse of a certain time after charging the photoconductor drum to identify the photoconductor drum. It is desirable to judge whether or not the part of is deteriorated due to fatigue.

[0017]

1 is a front view showing the structure of a charge distribution measuring apparatus of the present invention. As shown in the figure, the charge distribution measuring device 1 charges the surface of, for example, the photosensitive drum 2 and measures the surface potential distribution, and the charging unit 3, the exposure unit 4, and the surface potential meter 5 are exposed to light. It is arranged at an angle θ, for example, θ = 45 degrees, along the circumferential direction of the body drum 2. This angle θ is 360 / N · (number of units used-1), where N is an integer of 2 or more, and when the radius of the cylindrical drum to be measured is r, the inner cylindrical shape of the arrangement unit excluding the surface electrometer It is determined to have a relationship of θ · (2πr / 360) ≧ k with respect to the value k of the maximum operating range in the circumferential direction on the drum. The surface electrometer 5 may be one normally used in an electrophotographic process, or one having a higher spatial resolution than that, that is, one having a narrow detection range. As shown in the side view of the charge distribution measuring device 1 in FIG. 2, the photoconductor drum 2 includes a rotation driving device 7 having a photoconductor drum rotation motor 6.
Is attached to. The charging unit 3 is provided in the feeding device 9 which reciprocates along the axial direction of the photoconductor drum 2 by the charging unit feed motor 8, and the exposure unit 4 is moved along the axial direction of the photoconductor drum 2 by the exposure unit feed motor 10. The surface electrometer 5 is provided on the reciprocating feeding device 11, and the surface electrometer 5 is driven by the surface electrometer feeding motor 12 to the photosensitive drum 2
It is provided in the feeding device 13 that reciprocates along the axial direction of.

The control device 14 of the charge distribution measuring device 1
Is the controller 15 as shown in the block diagram of FIG.
It has a charging / exposure controller 16 and a drive controller 17. The controller 15 sends a control signal to the charging / exposure control unit 16 and the drive control unit 17 according to the measurement conditions input from the input device 18 and a control program stored in advance, and samples and saves the surface potential signal measured by the surface potential meter 5. At the same time, the stored surface potential signal is processed into a graph and displayed on an output device 19 such as a display or a printer for recording. The charging / exposure control unit 16 controls the voltage output from the high-voltage power supply 20 to the charging unit 3 by a control signal sent from the controller 15, turns on / off the exposure light source 21 and opens / closes the shutter 22 to open / close the exposure unit 4. Control the exposure beam sent to. That is, it takes a certain time, for example, 5 to 10 minutes until the light intensity becomes stable after the exposure light source 21 using a halogen lamp or LED is turned on. Furthermore, if the lighting voltage is changed during lighting, it takes time to stabilize. Therefore, the exposure light source 21 is turned on before the measurement is started, and when the exposure is performed, the exposure beam is sent to the exposure unit 4 by opening and closing the shutter 22 to perform exposure with light of stable intensity. The drive control unit 17 controls the drive of the charging unit feed motor 8, the exposure unit feed motor 10, the surface potential meter feed motor 12, and the photoconductor drum rotation motor 6 by the control signal sent from the controller 15.

Charge distribution measuring device 1 constructed as described above
When the surface of the photoconductor drum 2 is charged with and the surface potential is measured, first, the photoconductor drum 2 is mounted on the rotation driving device 7, and the charging unit 3, the exposure unit 4, and the surface potential meter 5 are connected.
Is arranged at the initial position on one end side of the photosensitive drum 2. Then, the surface of the photosensitive drum 2 is cleaned to remove dust and the like. In other words, if dust or the like adheres to the surface of the photoconductor drum 2, the dust or the like becomes a potential defect spot when the photoconductor drum 2 is charged, which causes defects such as scratches on the surface or foreign matter adhered during coating. Dust and the like should be removed beforehand, as they will not be distinguishable. The dust and the like can be removed by using air, but since dust and the like may fly and adhere to the surface only by blowing the air, it is preferable to inhale or combine air blowing and inhalation.

With the surface of the photosensitive drum 2 clean
When the first measurement is started, the feeding device 9 is driven while applying the preset charging voltage from the high-voltage power supply 20 to the charging unit 3 to move the charging unit 3 in the axial direction of the photosensitive drum 2 at a constant speed V. Then, the surface of the photosensitive drum 2 is charged. When the charging unit 3 reaches the measurement end position of the other end of the photosensitive drum 2, the voltage supplied to the charging unit 3 is turned off to return the charging unit 3 to the initial position, and the rotation driving device 7 rotates the photosensitive member. Drum 2 at a certain angle,
For example, the exposure unit 4 is rotated by 45 degrees and is moved by the feeding device 10 in the same direction as the moving direction when the surface of the photoconductor drum 2 is charged by the charging unit 3 at the same speed V as the moving speed of the charging unit 3. While moving, the surface of the charged photosensitive drum 2 is exposed. When the surface of the photosensitive drum 2 is exposed, the rotation driving device 7 rotates the photosensitive drum 2 again at a fixed angle, for example, 45 degrees, and the surface electrometer 5 is fed by the feeding device 13 by the charging unit 3 of the photosensitive drum 2. The potential of the surface of the photoconductor drum 2 is measured while moving at the same speed V as the moving speed of the charging unit 3 in the same direction as the moving direction when charging the surface. The controller 15 samples and stores the surface potential signal measured by the surface potential meter 5 at a constant timing, for example, at a pitch of 0.1 mm in the axial direction of the photosensitive drum 2.

In order to charge the surface of the photosensitive drum 2 in this way, the charging unit 3 is in the same direction as when the charging unit 3 is moved along the axial direction of the photosensitive drum 2, and the charging unit 3
The exposure unit 4 and the surface electrometer 5 at the same speed V as when moving the
By measuring the surface potential of the surface of the photosensitive drum 2, the surface potential can be measured by the surface potential meter 5 at the respective positions on the surface of the photosensitive drum 2 when the same time has elapsed since the charging by the charging unit 3. The measurement conditions of the surface potential at each position of the body drum 2 can be the same. Further, when measuring the surface potential of the photoconductor drum 2, if a surface electrometer 5 that is usually used in an electrophotographic process is used, the detection range of the surface electrometer 5 is, for example, 10 mm to 15 mm in diameter.
mm, and the charging unit 3 needs to have a size in the circumferential direction that covers at least this range.
Needs to have an exposure range that covers all of this charging area, and when the charging, exposure and measurement of the surface potential are repeated while rotating the photosensitive drum 2 by a certain angle θ, the angle θ has a certain magnitude. Otherwise, the measured surface potential will be affected by the previous measurement. Therefore, the angle θ is 36
0 / N- (number of units used-1), where N is an integer of 2 or more, and when the radius of the cylindrical drum to be measured is r, the circumferential direction to the inner cylindrical drum of the arrangement unit excluding the surface electrometer For the value k of the maximum operating range of θ, (2π
By determining that the relationship of r / 360) ≧ k is satisfied, the influence of the previous measurement can be removed and the surface potential can be measured accurately.

When repeating the charging, the exposure and the measurement of the surface potential while rotating the photosensitive drum 2 at a constant angle,
By arranging the charging unit 3, the exposure unit 4, and the surface electrometer 5 at a constant angle with respect to the circumferential direction of the photoconductor drum 2, the exposure unit 4 simultaneously charges the surface of the photoconductor drum 2 while exposing it. Unit 3 is photoconductor drum 2
Since the surface of the next measurement position can be charged, charging, exposure, and measurement of the surface potential can be performed in parallel, and the efficiency of measurement can be improved.

The controller 15 uses the photosensitive drum 2
Charging, exposure, and measurement of surface potential are repeated while rotating the photosensitive drum 2 by a constant angle, and when the photosensitive drum 2 makes one rotation, for example, an AC voltage is applied to the charging unit 3 to move the charging unit 3. And the rotation of the photoconductor drum 2 are repeated to remove the charge on the surface of the photoconductor drum 2, and the charge is displaced from the measurement position at the first rotation in the circumferential direction of the photoconductor drum 2 by a constant pitch, for example, in the range of 1 mm to 5 mm. At the second rotation, charging, exposure, and surface potential measurement are performed. By repeating the charging, the exposure, and the measurement of the surface potential, the surface potential signal of the entire surface of the photosensitive drum 2 is sampled at a constant pitch. The sampled surface potential signal is data-processed into a graph, which is displayed and recorded on the output device 19 such as a display or a printer.

In the above description, the case where the surface of the photoconductor drum 2 is neutralized by applying an AC voltage to the charging unit 3 after the photoconductor drum 2 has been rotated once and the measurement of the first rotation has been completed has been described. However, when returning the surface electrometer 5 whose surface potential has been measured to the initial position, the surface of the photosensitive drum 2 may be neutralized with a static elimination brush or the like.

The charging distribution measuring device 1 has been shown in the case where the charging unit 3 and the exposure unit 4 are provided in different feeding devices 9 and 11, but as shown in the side view of FIG. 4 is provided in the same feeding device 23, and the feeding device 23 performs charging and exposure while moving the charging unit 3 and the exposure unit 4 in the axial direction of the photoconductor drum 2, and then the surface potential is measured by the surface potential meter 5. You may do it. In this way, by providing the charging unit 3 and the exposure unit 4 in the same feeding device 23, the structure of the charge distribution measuring device 1 can be simplified, and the surface of the photoconductor drum 2 can be continuously charged and exposed. By doing so, it is possible to shorten the measurement time when the photosensitive drum 2 is rotated once, and it is possible to improve the measurement efficiency of the surface potential.

Further, as shown in FIG. 5, the charging unit 3, the exposure unit 4, and the surface electrometer 5 are connected to the photosensitive drum 2.
Alternatively, the measuring unit 24 may be arranged in the axial direction, and the measuring unit 24 may be moved by the feeding device 25. As described above, the charging unit 3, the exposure unit 4, and the surface potential meter 5 are arranged in the axial direction of the photoconductor drum 2 to form the measuring unit 24.
The configuration of can be simplified.

In this case, while the measuring unit 24 is moved by the feeding device 25, the charging and exposure of the surface of the photosensitive drum 2 and the measurement of the surface potential are continuously performed, or after the charging unit 3 charges the measuring unit 24. After returning 24 to the initial position, exposure is performed by the exposure unit 4, and then the measurement unit 2
The charging, the exposure, and the measurement of the surface potential may be performed intermittently so that 4 is returned to the initial position and the surface potential is measured by the surface potential meter 5. In either case, the surface potential is measured by the surface potential meter 5, and when the measurement unit 24 is returned from the measurement end position to the initial position, an AC voltage is applied to the charging unit 3 to eliminate the surface of the photoconductor drum 2. Or by removing the charge with a charge removing brush or the like, for example, in the circumferential direction of the photosensitive drum 2,
It is possible to perform charging, exposure, and measurement of the surface potential while shifting the measurement line by mm pitch. In this way, the measurement time can be further shortened.

Further, when the charging, the exposure and the measurement of the surface potential are continuously carried out, a local defect such as a pinhole or coating unevenness of the charge generation layer, in which the difference between the normal part and the abnormal part is easily clarified immediately after the charging. It is possible to accurately detect a difference in sensitivity characteristic due to the above, or a difference in sensitivity characteristic due to uneven thickness of the charge transfer layer. In other words, the potential dropped in the pinhole does not change with the passage of time after charging,
The potential of the normal part decreases due to dark decay, and the potential contrast between the normal part and the abnormal part becomes small, making it difficult to detect pinhole parts, but this effect can be eliminated by measuring the potential immediately after charging. . In addition, when a part of the used photoconductor drum 2 is fatigued, the potential decay (dark decay) of the fatigued part progresses after a lapse of time from charging, and the difference from the normal part becomes clear and abnormal. Can be easily detected.

Further, when detecting a fatigue-deteriorated portion of the photosensitive drum 2, if the surface potential is measured after a predetermined time, for example, 10 to 20 seconds, after charging and exposure, the fatigued portion or fatigue is detected. The state of can be clarified. Therefore, the charge distribution measuring device 1 is downsized and mounted on an image forming apparatus such as a copying machine or a printer, and the potential distribution of the photoconductor drum 2 is measured when the number of printed sheets is increased, at the time of startup or standby, and It is possible to determine whether or not a specific portion of the drum 2 is fatigued and deteriorated.
From the results, it is possible to improve the reliability of the image forming apparatus by, for example, using a heater provided in the vicinity of or inside the photoconductor drum 2 to recover from fatigue and displaying on the display unit that the photoconductor drum 2 is about to be replaced. Can be increased.

Further, as shown in FIG. 5, two sets of measuring units 24 having the charging unit 3, the exposure unit 4 and the surface electrometer 5 may be provided at positions where the angles differ by 180 degrees in the circumferential direction of the photosensitive drum 2. When the diameter of the photoconductor drum 2 to be measured is large, as shown in the front view of FIG. 6, four sets are provided at positions where the angles differ by 90 degrees in the circumferential direction of the photoconductor drum 2, so that the measurement time of the surface potential is increased. Can be significantly shortened to improve the measurement efficiency. For example, the diameter is 30mm,
Measure the photoconductor drum 2 with a length of 340 mm with the measurement unit 2
4 is moved at a speed of 50 mm / s, the charging unit, the exposure unit, and the surface potential are continuously measured.
Takes 6.8 to move from the initial position to the measurement end position.
Seconds. When the measurement is repeated at a pitch of 1 mm in the circumferential direction of the photoconductor drum 2, the time required to measure the entire surface of the photoconductor drum 2 with one set of measurement units 24 is 6.8 × 2 × 94.2 =
It takes 1281 seconds (about 21 minutes), but two sets of measurement units 24
This measurement time can be halved by using.

The charge distribution measuring device 1 is a photosensitive drum 2.
Although the case where the surface of the photosensitive drum 2 is exposed after being charged and then the surface potential is measured has been described, in order to detect a local defect such as a pinhole, the surface of the photosensitive drum 2 is charged and exposed. The surface potential may be measured immediately.

The case of measuring the surface potential distribution of the photosensitive drum 2 with the charge distribution measuring device 1 has been described.
As with the photoconductor drum 2, not only the surface potential distribution on the surface of the photoconductor but also the surface potential distribution on the surface of the insulator can be measured in the same manner.

[0033]

[Example] For example, a model 344 of Trek Japan Co., Ltd. is used as the surface electrometer 5, a model 555P-4 is used as the probe, a corona charging device of the scorotron system is used as the charging unit 3, and the light is emitted from the exposure unit 4. The exposure beam is a monochromatic light in which a halogen lamp light source is combined with a bandpass filter, and the charge distribution measuring apparatus 1 shown in FIG. 1 is configured, and a red LED is used for discharging the photosensitive drum 2. The photosensitive drum 2 has a diameter of 30 mm,
Surface potentials were measured using two types of lengths of 256 mm and 340 mm, and the sampled surface potential signals were subjected to data processing and graphed results are shown in FIGS. 7 to 14. 7 to 14, the X axis represents the measurement position in the axial direction of the photosensitive drum 2, the Y axis represents the measurement position in the circumferential direction, and the Z axis represents the measured value (V) of the surface potential at each position. In this measurement, the charging unit 3 is moved in the axial direction of the photosensitive drum 2 at a moving speed of 60 m.
m / s (displayed as (× 0.12mm) in the X-axis title in the graph) and 50mm / s (in the X-axis title in the graph (× 0.
The surface of the photoconductor drum 2 was exposed. The exposure unit 4 and the surface potential meter 5 were moved in the same direction at the same speed as the charging unit 3 to measure the exposure and the surface potential. The data sampling rate was set to 500 s / s at any moving speed. However, since the amount of sampling data is large, some data are thinned out in the graph display ((X 0.2 mm) is displayed in the X-axis title in the graph). In the measurement, the length from one end of the photosensitive drum 2 is about ⅔, and the number of times of measurement in the circumferential direction is 94.2 mm.
1mm pitch (for the Y-axis title in the graph (m
m)) and 2 mm pitch (Y axis title in the graph is indicated as (× 2 mm)).

In FIG. 7, a blade of a cutter knife was put on the surface of the normal photosensitive drum 2 to scratch one point. The position of the scratch was about 100 mm from the end and about 20 mm from the measurement start position in the circumferential direction. As shown in FIG. 7, the potential distribution was flat and good data were obtained.
It can be determined that the charging is abnormal at the scratched position.

FIG. 8 shows the photosensitive drum 2 in the central portion 60 in the axial direction.
mm width, electrified in the range of width 40mm, the part is width 60m
Repeatedly exposing with m and removing static electricity with a width of 120 mm,
A sample in which the electrostatic characteristics of the photoconductor were partially deteriorated was used. When measuring the surface potential, the charging unit 3 sets the charging potential level to about 800 to 850 V, and after charging, the surface potential meter 5 measures the surface potential and samples it. As shown in the figure, a band-shaped portion whose characteristics are deteriorated along the circumferential direction is clarified in a part of the axial direction. FIG. 9 shows the result of measuring the surface potential by charging the charging unit 3 by raising the charging potential level to 900 to 950V. By increasing the charging potential level in this way, the deteriorated portion could be made clearer. When a three-dimensional graph display showing this deteriorated portion is displayed from a different viewpoint, it becomes as shown in FIG. 10, and it was confirmed that there is a potential drop due to deterioration in the central portion. After observing the surface of the photosensitive drum 2 after this measurement, foreign matter was recognized. Therefore, after the surface was cleaned by blowing and sucking air, the charging and the potential measurement were repeated again. As a result, as shown in FIG. The descent is no longer recognized.

Further, the charging potential level of the charging unit 3 is
The result of measuring the surface potential after charging for 15 seconds after charging at 900 to 950 V is shown in FIG. As shown in FIG. 12, since the dark attenuation characteristic of the deteriorated portion is deteriorated, the potential drop with respect to the surroundings is large and the deteriorated portion is more clear.

Further, FIG. 13 shows the result of measuring the surface potential by charging the photosensitive drum 2 having a thickness of about 30 μm and having an abnormal thickness of the charge transfer layer. FIG. 14 shows the result of measuring the surface potential after performing exposure under the condition that 900 V is attenuated to 600 V. As shown in FIGS. 13 and 14, it was clarified that the potential level was disturbed due to an abnormality in the film thickness of the charge transfer layer.

[0038]

As described above, according to the present invention, when the surface of the cylindrical drum is charged and the surface potential is measured, the surface potential measuring unit is moved in the same direction as the moving direction when the charging unit charges. By moving in the axial direction of the cylindrical drum at the same speed as the moving speed of the charging unit and measuring the surface potential of the charged and charged / exposed cylindrical drum, the surface at each position of the cylindrical drum is measured. The surface potential distribution of the cylindrical drum can be accurately measured under the same potential measurement conditions.

Further, the charging unit and the surface potential measuring unit or the charging unit, the exposing unit and the surface potential measuring unit are arranged at an equal angle θ along the circumferential direction of the cylindrical drum, and the angle θ (degree) is 360 / N. (Number of units used −
1) where N is an integer of 2 or more, and when the radius of the cylindrical drum to be measured is r, the value k of the maximum operating range in the circumferential direction of the inner cylindrical drum of the arrangement unit excluding the surface electrometer , Θ · (2πr / 360) ≧ k, the cylindrical drum is rotated by an angle of θ, and charging and surface potential measurement or charging, exposure, and surface potential measurement are repeated. When the cylindrical drum makes one rotation, rotate the cylindrical body at an arbitrary angle and repeat the above operation from the beginning to remove the effects of charging and exposure from the previous measurement, and to accurately measure the surface potential. it can.

Further, by continuously charging the cylindrical drum and measuring the surface potential, it is possible to accurately detect a local defect in which the difference between the normal portion and the abnormal portion is apt to become clear immediately after the charging.

In addition, when a partial area of the cylindrical drum is fatigued, the potential attenuation (dark attenuation) of the fatigued part progresses with time after charging, and the difference from the normal part becomes clear and abnormal. Since it becomes easier to detect, the fatigued portion and the fatigued state can be clarified by measuring the surface potential after a lapse of a fixed time after charging the cylindrical drum.

Further, the charging unit and the surface potential measuring unit or the charging unit, the exposing unit and the surface potential measuring unit are provided with a photoconductive or insulating film, and the shaft of a cylindrical drum mounted on the rotary driving device. The surface of the cylindrical drum at each axial position is measured by charging and exposing the surface of the cylindrical drum and measuring the surface potential while moving the measuring units, which are arranged side by side and integrated, in the axial direction of the cylindrical drum by the feeder. The measurement conditions of the electric potential can be the same.

By arranging a plurality of sets of the above-mentioned integral measuring units at equal angles along the outer circumference of the cylindrical drum, the measurement efficiency of the surface potential can be improved.

Furthermore, when the surface potential of the cylindrical drum is measured and then the charge is removed from the cylindrical drum, and the surface potential is subsequently measured, the surface potential can be accurately measured by removing the influence of the previous charging. it can.

Further, the photoconductor drum is used as the cylindrical drum, and the image forming apparatus is provided with a charge distribution measuring device for measuring the surface potential after a lapse of a certain time after the photoconductor drum is charged to identify the photoconductor drum. It is possible to improve the reliability of the image forming apparatus by determining whether or not the part is fatigued and deteriorated.

[Brief description of drawings]

FIG. 1 is a front view showing the configuration of a charge distribution measuring apparatus of the present invention.

FIG. 2 is a side view showing the configuration of a charge distribution measuring device.

FIG. 3 is a block diagram showing a configuration of a control device.

FIG. 4 is a side view showing a configuration of a second charge distribution measuring device.

FIG. 5 is a side view showing a configuration of a third charge distribution measuring device.

FIG. 6 is a front view showing the configuration of a fourth charge distribution measuring device.

FIG. 7 is a surface potential distribution diagram of a photosensitive drum having a dot-like scratch.

FIG. 8 is a surface potential distribution diagram of the photosensitive drum whose central portion is deteriorated.

FIG. 9 is a surface potential distribution diagram when a photosensitive drum having a deteriorated central portion is charged with a high potential.

FIG. 10 is a surface potential distribution diagram showing a different viewpoint when the photosensitive drum whose central portion is deteriorated is charged at a high potential.

FIG. 11 is a surface potential distribution diagram of the photosensitive drum from which foreign matter is removed.

FIG. 12 is a surface potential distribution diagram of the photosensitive drum when the surface potential is measured after a lapse of a fixed time after charging.

FIG. 13 is a surface potential distribution diagram when the surface potential is measured by charging a photosensitive drum having an abnormal thickness of the charge transfer layer.

FIG. 14 is a surface potential distribution diagram when the surface potential is measured by charging and exposing a photosensitive drum having an abnormal thickness of the charge transfer layer.

[Explanation of symbols]

1; Charge distribution measuring device, 2; Photosensitive drum, 3; Charging unit, 4; Exposure unit, 5; Surface potential meter, 6; Rotation motor, 7; Rotation drive device, 8; Charging unit feed motor, 9; Feed Device, 10; exposure unit feed motor, 1
1; Feeding device, 12; Surface electrometer feed motor, 13; Feeding device, 14; Control device, 15; Controller, 16;
Charging / exposure controller, 17; drive controller, 18; input device, 19; output device, 20; high-voltage power supply, 21; exposure light source, 22; shutter.

Claims (9)

[Claims] 1. A photoconductor or an insulator film is formed, and at least a charging unit and a surface potential measuring unit are separately arranged around a cylindrical drum mounted on a rotary driving device, and the charging unit is fed by a feeding device. The surface of the cylindrical drum is charged while moving in the axial direction of the cylindrical drum, and the surface potential measuring unit is in the same direction as the moving direction when charging by the charging unit, at the same speed as the moving speed of the charging unit,
A charge distribution measuring device characterized by moving a surface of a cylindrical drum by a feeder to measure the surface potential of the charged cylindrical drum. 2. A photoconductor or insulator film is formed, and at least a charging unit, an exposure unit, and a surface potential measuring unit are individually arranged around a cylindrical drum mounted on a rotary driving device, and the charging unit is The transfer device charges the surface of the cylindrical drum while moving in the axial direction of the cylindrical drum, and the charging unit charges the exposure unit while moving the exposure unit in the axial direction of the cylindrical drum at the same speed as the moving speed of the charging unit. The drum surface is exposed, and the surface potential measuring unit is moved in the axial direction of the cylindrical drum by the feeding device at the same speed as the moving speed of the charging unit in the same direction as the moving direction when charging by the charging unit and charging A charge distribution measuring device characterized by measuring the surface potential of an exposed cylindrical drum. 3. The units are arranged at an equal angle θ along the circumferential direction of the cylindrical drum, and the angle θ (degree) is 360 / N.
(The number of used units-1), where N is an integer of 2 or more, and when the radius of the cylindrical drum to be measured is r, the operating range in the circumferential direction of the arrangement unit excluding the surface electrometer on the inner cylindrical drum is For the maximum value k, θ · (2πr / 36
0) ≧ k, the cylindrical drum is rotated by an angle θ, and charging and surface potential measurement or charging, exposure, and surface potential measurement are repeated, and when the cylindrical drum rotates once, The charge distribution measuring device according to claim 1, wherein the cylindrical body is rotated by an arbitrary angle and the above operation is repeated from the beginning. 4. The charge distribution measuring device according to claim 1, wherein the charging of the cylindrical drum and the measurement of the surface potential are continuously performed. 5. The charge distribution measuring device according to claim 1, wherein the surface potential is measured after a lapse of a fixed time after charging the cylindrical drum. 6. A shaft of a cylindrical drum having a charging unit and a surface potential measuring unit or a charging unit, an exposing unit and a surface potential measuring unit, on which a photoconductive or insulating film is formed and which is mounted on a rotation driving device. A charging distribution measuring device characterized by performing charging and exposure of the surface of a cylindrical drum and measurement of the surface potential while moving a measuring unit which is lined up and integrated in one direction in the axial direction of the cylindrical drum by a feeding device. 7. The charge distribution measuring device according to claim 5, wherein a plurality of sets of the measuring units are arranged at equal angles along the outer circumference of the cylindrical drum. 8. The charge distribution measuring device according to claim 1, wherein the charge is removed from the cylindrical drum after the surface potential of the cylindrical drum is measured. 9. An image forming apparatus comprising the charge distribution measuring device according to claim 5.