JP4620429B2 - Photoreceptor characteristic evaluation device - Google Patents

Description

  The present invention relates to a method for reading a surface potential of a photoconductor and an apparatus for evaluating the characteristics of a photoconductor, and in particular, in automatic reading of a measured potential signal, it is not affected by the uncertainty of the periodicity of the potential signal and has various signal levels. The present invention relates to a method for reading the surface potential of a photoconductor and a photoconductor characteristic evaluation apparatus that are not affected by noise superimposed on a signal.

  An electrophotographic method used in a copying machine or a laser printer is formed by a process of uniformly charging the surface of a photoconductor and a process of exposing the charged photoconductor surface to form an electrostatic latent image on the surface of the photoconductor. Developing the electrostatic latent image with toner in the developer, transferring the toner image to paper or an intermediate transfer belt, fixing the transferred toner image, and on the photoreceptor after transfer It consists of a cleaning process for removing residual toner and a charge eliminating process for removing the electrostatic latent image on the photoreceptor.

  Although the characteristics of the photoconductor are greatly related to the exposure process, since each process acts on the output quality of the final image, it is not easy to know the latent image quality in the exposure process from the final image quality. Therefore, the charging potential for a certain charging condition and the post-exposure potential for a certain exposure condition are measured with a surface potential measurement probe placed at the developing unit position, and how this measurement value changes under the environment of temperature and humidity. Alternatively, the quality of the latent image formed is estimated by seeing how it changes after repeated cycles of charging and exposure, and is fed back to the design of the photoconductor and the image forming process. Methods have been taken to improve the forming process.

  As described above, in the electrophotographic field, measuring the surface potential on the photoreceptor, particularly the post-exposure potential, is an extremely important measurement not only for the photoreceptor designer but also for the image forming process designer. Therefore, the measurement of the post-exposure potential is performed very frequently, and a large amount of data appears (see, for example, Patent Document 1).

JP 2000-275872 A

  However, in this post-exposure potential measurement, the post-exposure potential signal has a substantially square wave shape with respect to time, and the width thereof is, for example, a potential width (time) corresponding to A4 horizontal size 210 mm in A4 size lateral feed image writing. When the measurement is repeated, the photoconductor becomes fatigued and contains a lot of noise, and it is difficult to read the surface potential level after exposure later. It will be a hassle. There is a demand for automation of this reading, but it has not been realized yet.

The reason for this is considered as follows.
(1) All recorded potential signals do not have perfect periodicity. If the periodicity is maintained, once the initial position at which the captured signal is read out is determined, it is easy to read out the potential level after changing the position at which the signal is read out at regular intervals. The uncertainty of periodicity is likely to occur when a life test is performed using an actual machine, that is, when charging and exposure are repeated. When repeated charging and exposure cycles are performed, the post-exposure potential is often measured as an intermediate check.

  Therefore, only in this case, the potential signal is fetched several times, and when it is finished, the charging and exposure cycles are restarted. This is repeated, but the number of potential signals that are checked several times during the check may vary depending on the situation at that time, and the start and end times of the acquisition are not constant, and the entire signal cycle Sex is uncertain.

(2) For the same reason, the periodicity of the potential signal obtained due to insufficient accuracy of the measuring device may be uncertain. In order to evaluate the sensitivity characteristics of the photoconductor, the exposure power of the exposure device is sequentially changed, a number of post-exposure potential signals are read in a short time, and the relationship between the exposure energy (E) and the post-exposure potential (V) is displayed. There is a measurement of optical attenuation characteristics.
In the measurement of the light attenuation characteristics of the photoconductor, the exposure power switching time varies by several tens of milliseconds due to the accuracy of the measuring apparatus. If there are many exposure power switching, this variation accumulates as the data becomes later. Uncertainty of periodicity increases, and a reading method based on signal periodicity becomes impossible.

  This is why there is a need for a reading method that does not depend on the periodicity of the recorded signal, but as a method that is immediately noticed, there is a device corresponding to the timing at which the post-exposure potential signal starts and ends. The trigger signal is issued from the side. There is a method in which this trigger signal is input to a CH (channel) different from the potential signal, or A / D conversion start and end of the surface potential signal is performed by this trigger signal.

  With this method, since the start and end of each potential data can be known, no error occurs in potential reading. The disadvantage of this method is that if there is no mechanism for issuing a trigger signal on the apparatus side, it is necessary to work. The life test or the like is often performed using an actual copying machine or laser printer, and such trigger signal output is often not prepared.

  From the above, as an automatic reading method of the measured potential signal, (a) it is not affected by the uncertainty of the periodicity of the signal, (b) it is not affected by various signal levels, and (c) it is not affected by noise in the signal. Thus, a simple data reading algorithm is required.

  In view of the above, the present invention is an automatic reading method of a measured potential signal that is not affected by the uncertainty of signal periodicity, is not affected by various signal levels, and is not affected by noise superimposed on the signal. It is to provide an automatic data reading algorithm.

It is another object of the present invention to provide an evaluation apparatus that automatically reads a continuous post-exposure potential from the measurement of a potential signal and evaluates the photoconductor light attenuation characteristics fully automatically .

In order to achieve this object, at least a charger, an exposure unit, a surface potential measuring probe, and a charge eliminator are arranged in the vicinity of a rotatable photosensitive drum, and a potential signal detected by the surface potential measuring probe is received. In a method comprising a signal processing device for A / D conversion and storing, and reading the surface potential of a photoconductor at a predetermined position from a surface potential signal stored in the signal processing device,
A method of generating a binarized signal from the surface potential signal recorded in the signal processing device and reading the surface potential based on the generated binarized signal may be used .

  In this way, for example, as shown in FIGS. 4 and 10, a threshold is applied to the surface potential signal to generate binary data, and based on the information of the binary data, a predetermined value is obtained from the original surface potential signal. Since the surface potential of the position is read, the binarized surface is not affected by the uncertainty of the signal periodicity (FIG. 10), is not affected by various signal levels, and is not affected by noise superimposed on the signal. Potential data can be obtained.

Further, the surface potential reading method of the photosensitive member,
The recorded surface potential signal may have a substantially square wave shape, and the square wave may be continuous during repeated measurement.
In this way, the reading operation can be performed accurately and in a short time.

Further, the surface potential reading method of the photosensitive member,
Order of appearance of the generally square-wave shape potential signal, the rise start point, falling to recognize the end point method and result good you read the potential level of the original potential signal.

  In this way, based on the generated binarized data, the appearance order, the rising start point, and the falling end point of the original substantially square-wave potential signal are recognized, and the potential level of the original potential signal is read. As a result, an accurate potential level of the original potential signal can be obtained.

In order to achieve this object, the invention described in claim 1 includes a charger for charging a rotatable photosensitive member , and an exposure unit for writing image information on the surface of the charged photosensitive member to form an electrostatic latent image. A probe for measuring the surface potential of the electrostatic latent image, a static eliminator for erasing the electrostatic latent image on the surface of the photoconductor, and the charger charged while rotating, and statically changing the exposure energy sequentially with the exposure device. wherein the surface of the photosensitive member potential signal substantially square-wave shape obtained by measuring by the probe is a / D converted to latent image is formed, a signal processing device for storing, was recorded to the signal processing unit the generally based on a predetermined threshold from the potential signal of the square wave shape generates binary data, order of appearance of the square wave at the potential signal to be recognized on the basis of the binarized data, the rise start point , End of falling From reading the potential level between the rise start point and the falling end point of each square wave of the voltage signal automatically, and an information processing apparatus for outputting the potential characteristics of the photosensitive member based on a potential level read the And a photoreceptor characteristic evaluation apparatus .
According to a second aspect of the present invention, there is provided the photosensitive member property evaluation apparatus according to the first aspect, wherein the information processing apparatus determines the exposure energy and the potential of the surface of the photosensitive member after the exposure based on the automatically read potential level. The relationship is output.

  In this way, no additional equipment is required in the conventional potential measuring device, no difference in reading by humans is made, the reading operation is shortened quickly, and the data is digitized. Therefore, it is possible to eliminate the need for output to paper and provide an environment-friendly photoconductor characteristic evaluation apparatus.

According to the present invention, no new additional equipment is required for the conventional potential measuring device, no difference in reading by humans is made, the reading operation is shortened quickly, and the data is digitized. Therefore, it is possible to eliminate the need for output to paper and provide an environment-friendly photoconductor characteristic evaluation apparatus.

[I] Outline and Principle of the Present Invention Prior to the description of the embodiments of the present invention, the outline of the present invention and the principle of the present invention will be described. In addition, a specific description of the prior art is partially included.
In the field of electrophotography, measuring the surface potential on the photoconductor, especially the surface potential after exposure, greatly affects the image quality because the level and fluctuation of this potential are related to the photoconductor designer, image generation process designer, quality assurance. Frequently performed by the person in charge. Therefore, it is extremely rare that there is only one potential signal data after exposure even in one measurement, and a plurality of data are often connected in series.

The potential signal detected by the surface electrometer probe is processed by the surface electrometer main body, the result is displayed on the display of the surface electrometer, and the analog output of the surface electrometer is connected to the recorder and recorded.
Many conventional “recorders” are recorded on paper with a pen (ink), but at present, digital recorders that perform A / D conversion and store signals are the mainstream.

In the former, the post-exposure potential is read manually, but if there is a large amount of data, it is easy to make a mistake in reading, and if noise is superimposed on the signal, the reading error becomes even larger.
Many of the latter digital recorders have a signal waveform monitor. Depending on the scale of the coordinate axis displayed on the monitor, it can be read directly by the human eye, or the cursor can be operated, and the cursor can be superimposed on the data to be read. Many read values. Again, human operation is required, and it is difficult to continue reading accurately when there is a large amount of data.

  In order to solve this, there is an attempt to copy data stored in a digital recorder to a PC (personal computer) and automatically read the data by a program created in advance. In addition, the function of the digital recorder is given to the PC (A / D conversion board or A / D conversion card is installed as a peripheral device of the PC), and the PC storage device (main unit memory or external storage device) is used. The same is true for recording signals and attempting to read data based on this.

  Attempts to create a program and read it automatically take advantage of the periodicity of how the potential signal appears. If the recorded data has periodicity, the first position to be read is determined, and thereafter, the read position is changed at regular intervals, and the potential level is read periodically.

  Here, the “data position” is represented by the number of A / D converted sampling points from the beginning. This is a periodic reading method based on the assumption that data has periodicity. As long as there is no uncertainty in the assumptions, there will be no problems. As described above, the uncertainty of periodicity is likely to occur when a life test is performed using an actual machine, that is, when a repeated cycle of charging and exposure is performed.

  Further, the increase in the above-described reading error also occurs due to the uncertainty of the timing control accuracy of the evaluation apparatus. If there is uncertainty in the periodicity of the data, the reading position will be distorted and reading will fail. For this reason, even if there is uncertainty in the periodicity of the data, or even when potential data is connected at random, a trigger signal from the apparatus side is synchronized with the writing start and end of the exposure apparatus as a method of reading without problems. It is possible to consider how to make This trigger signal is made to correspond to the timing when the potential signal rises and falls. This trigger signal is input to a CH (channel) different from the potential signal.

  Alternatively, it may be possible to start and end the A / D change of the surface potential signal with this trigger signal. According to this method, since the data position of the start and end of each potential data can be known, no error occurs in potential reading even if the data has no periodicity. The only disadvantage of this method is that if there is no mechanism for issuing a trigger signal on the device side, it is necessary to work.

  The present invention adopts the following method as an algorithm for reading potential data at a predetermined position from only potential signal data regardless of whether or not the recorded potential signal is periodic.

(1) A threshold (threshold value) is designated for the recorded potential signal data, and binary data (data composed of 0 and 1) is generated. That is, data that exceeds the threshold is replaced with 1, and data that is less than the threshold is replaced with 0. The generated binary data is a square wave (High 1, Low 0) with uniform levels. An example of binarized data for a general signal that is not limited to potential data is shown in FIG.

(2) Check whether a binary square wave has been generated corresponding to all potential signals having a substantially square wave shape. If there is something missing, the threshold value is changed and binary data is generated again. As the threshold value, an intermediate value between the minimum level (absolute value) of the original potential signal and the potential level after static elimination is designated.

(3) Based on the generated binary data, search for the position where the binary square wave rises from low to high, the position where it falls to low, and the order (number) of the square wave, and store it To do.
The search procedure is to set the binary data levels corresponding to the data points (0, 1, 2,..., I, i + 1, i + 2,...) To N ₀ , N ₁ , N ₂ ,. ..., N _i , N _{i + 1} , N _{i + 2} , ...
N ₁ -N ₀ = 0 or 1 (-1), N ₂ -N ₁ = 0 or 1 (-1) ... N _{i + 1} -N _i = 0 or 1 (-1)
Check sequentially. That is, the difference between adjacent data is sequentially examined. If the difference is 0, the next adjacent data difference is examined without any data change. If the difference is 1 (-1), there is a change in the data, and this point is set as the rising point (or falling point) of the data. (Refer to FIG. 5 described later)

If the recorded potential data starts from the static elimination potential, the binary data is N ₀ = 0, so N _{i + 1} -N _i = 1 at the position where the square wave rises, and the square wave rises, ie, the original The rise start position of the data potential signal is known. When the rising position of the square wave is known, the falling position is searched for, and the position where N _{i + 1} −N _i = −1 is checked and stored. Repeat this procedure until the end of the recorded data. (Refer to FIG. 6 described later)

In the search for the rising (falling) position, when N _i -N _i-1 = 0, N _{i + 1} -N _i = 1 (-1), N _{i + 2} -N _i = 1 It is preferable to check (1), and further confirm that N _{i + 3} −N _i = 1 (−1), and confirm that the rise (fall) is certain.

  In addition, based on the binarized data, the rising (falling) is determined by the difference (0, 1 or -1) between adjacent data, so the original data that changes the potential level or contains noise is used. It can be seen that it is possible to search for a rise (fall) with a much simpler algorithm than calculating the difference between adjacent data and determining the rise (fall) position.

(4) The obtained rise (fall) position information, that is, the rise start position, end position (and thus the width of the square wave), and what number data is the same as the original data, so apply it to the original data. Read the potential. In the reading at this time, sampling data included in a width determined by a position slightly advanced from the rising position and a position reversely moved from the falling position is read, an average value thereof is calculated, and output as potential data. Is preferred.

This is because abnormal data may appear at the end of the recorded potential signal data, and the potential level in the range from rising to falling is not constant, and fluctuations of several tens of volts often appear. This is to avoid those effects.
As mentioned above, it is an algorithm that generates binarized data from recorded data. Even if the recorded data is not periodic, the width of each data is different, and noise is superimposed on the data. However, potential data at a predetermined position can be read without any problem.

[II] Embodiment Hereinafter, the embodiment will be described more specifically with reference to the drawings.
[II-1] The first embodiment forms state Figure 2 is a diagram illustrating the embodiment, obtained from (A) is the photoconductor sensitivity characteristic evaluation apparatus of the layout, (B) is the photoconductor sensitivity characteristic evaluation apparatus It is a figure which shows the example of data. FIG. 3 is a diagram illustrating an example of process timing of the photosensitive member sensitivity characteristic evaluation apparatus. FIG. 4 is a diagram illustrating an example when binary data is generated from recorded data in the present embodiment.

As shown in FIG. 2A, around the photosensitive drum (OPC) 1, there are a charger (CH / Grid) 2, a static eliminator (QL) 3, and a first surface potential meter probe (VD). 4 and a second surface electrometer probe (VL) 5 are arranged, and laser writing is performed via a polygon mirror 6.
The first surface potential meter probe 4 performs potential measurement after charging, and the second surface potential meter probe 5 performs potential measurement after exposure.

The measurement system not shown is as follows.
(1) Measuring machine body: A device equipped with an LD (laser diode) writing device manufactured in-house.
(2) Surface electrometer: manufactured by Trek Japan, main unit (model 344) + electrometer probe (model 555P-4)
(3) A / D conversion, signal storage device: Yokogawa Electric Corporation digital scope DL708
(4) Information processing device (binarization, reading, storage, display): Commercial notebook PC + processing program by the present inventor
(5) Connection interface GP-IB of (3) and (4) above: PCMCIA GP-IB card, manufactured by Japan National Instruments Co., Ltd.

The measurement conditions are as follows.
Drum diameter = 30mmφ
Drum length = 340mm
Line speed = 125mm / s
Paper length = 210mm
Paper feed counter = 2
Pixel density = 600dpi
Time from exposure to development position = 110 ms (measures potential after exposure at "development position")
Beam size = 50x60 μm
Scorotron grid voltage = -600 (V)

The used photosensitive drum 1 is a negative charging drum manufactured in-house. The measured surface potential data is negative polarity, but unless otherwise noted, terms such as rising and falling are used for the absolute value of the data.
The measurement is repeated twice with one exposure energy, and then the measurement is repeated twice with different exposure energy. This was sequentially performed for 20 different exposure energies. The post-exposure potential analog-output from the surface electrometer is A / D converted and stored.

After a series of measurements is completed, the data is transferred to the PC that is the information processing apparatus via the interface. The threshold value was specified to −40 (V), and the binarization program was executed to generate binarized data. The generation procedure by the program is as described above.
Binarized data was generated corresponding to all post-exposure potential data (see FIG. 4).

  In this way, as is apparent from FIG. 4, the threshold is applied to the surface potential signal to generate binary data, and the surface potential at a predetermined position is generated from the original surface potential signal based on the information of the binary data. Therefore, it is possible to obtain surface potential data that is not affected by the uncertainty of the periodicity of the signal, is not affected by various signal levels, and is not affected by noise superimposed on the signal.

[II-2] shows the search position of the rising of the binary data (falling) in the second embodiment shaped state Figure 5 embodiment, illustrates a process flow chart of a data read in FIG. 6 in this embodiment It is.

For the generated square wave of the binarized data, the rising (falling) of the square wave is searched, and the position of the rising (falling) and the number of square waves are counted and stored (FIG. 5). reference). This search procedure is also as described above (see FIG. 6).
Next, the original post-exposure potential data was read from the information about the binarized data. The readout conditions are as follows: For one post-exposure potential data width, data is read for the range (sampling data number 61) in the range surrounded by the position advanced 15% from the rising position and the position advanced 15% from the falling position. Was calculated and transferred to commercial spreadsheet software for display.

  However, since the measurement was performed twice with the same exposure energy, the data for the second time was read and transferred to the spreadsheet software. In the case of specifying a condition where the measurement is repeated a plurality of times with one exposure energy, the program is designed so that the number of times of reading and displaying can be specified by the program.

  In this way, based on the generated binarized data, the appearance order, the rising start point, and the falling end point of the original substantially square-wave potential signal are recognized, and the potential level of the original potential signal is read. As a result, an accurate potential level of the original potential signal can be obtained.

[II-3] Third Embodiment shaped state 7 are in this embodiment is a diagram showing an example of a data range to read the reading start position, the average value. FIG. 8 is a diagram illustrating an example of normal reading end in the present embodiment. FIG. 9 is a diagram illustrating a measurement example of the photosensitive member sensitivity characteristic in the present embodiment.

  Measurement conditions similar to those of the first embodiment were set in the controller (= PC) of the measurement apparatus. Prior to the start of measurement, the exposure energy value was transferred from the controller to a predetermined column of commercial spreadsheet software. Start measurement, (1) Read post-exposure potential data in the same procedure (program) as in the first and second embodiments, and store the data in the column to the right of the column containing the exposure energy value of commercial spreadsheet software Was transferred.

  Graph drawing is set with the column where the exposure energy value is input in advance as the X axis and the column where the post-exposure potential data is input as the Y axis, so the post-exposure potential data for the exposure energy is drawn at the same time as the input. (See the table below and FIG. 9). The photosensitive member sensitivity characteristic evaluation was automatically executed without human data reading and keyboard re-input (see FIGS. 7 to 9).

  In this way, no additional equipment is required in the conventional potential measuring device, no difference in reading by humans is made, the reading operation is shortened quickly, and the data is digitized. Therefore, output to paper can be made unnecessary, and an environment-friendly measuring device can be provided.

[II-4] Fourth Embodiment shaped state diagram 10 is in this embodiment, is a diagram showing an example of a non-periodic data.
Surface potential signal data having no periodicity was generated (FIG. 10), and read by the program according to the algorithm of the first and second embodiments . The binarized data was generated without problems (FIG. 10), and the data could be read.

[II-5] Fifth embodiment (and comparative example)
FIG. 11 is a diagram showing recorded potential data and an example of binarization in the present embodiment. FIG. 12 is a diagram illustrating an example of potential reading start in the present embodiment. FIG. 13 is a diagram illustrating an example of normal reading end in the present embodiment. FIG. 14 is a diagram illustrating an example of starting a periodic reading method as a comparison with the present embodiment. FIG. 15 is a diagram illustrating an example of the end of the periodic reading method as a comparison with the present embodiment.

The same procedure as in the third embodiment was performed. The binarized data of the recorded surface potential signal could be generated without problems by setting the threshold to -18 (V) (FIG. 11), and the potential data could also be read (FIGS. 12 to 13).
A periodic reading method based on the periodicity of data was performed on the same surface potential signal. Since the procedure is a signal in which measurement is repeated twice for one exposure energy, the second measurement data of each exposure energy is read, and the distance D between the read data (= the number of sampling points between the data) is set. The position was sequentially changed by D and the potential was read (FIG. 14).

  The distance D between the data to be read was determined as follows. The falling position of the second exposure power data at the start of measurement and the falling position of the second data of the next exposure power were read by moving the cursor on the monitor, and the difference was calculated and measured. In this data, D was 426 points. When D was read in the same manner for the data located in the middle of all recorded signals and the data by the next exposure power, it was 425 points. The program specified 426 as the reading interval D. The average value of data between the two vertical cursors in the figure was read out. There is no problem immediately after the start of reading, but the reading range becomes inappropriate at the end (FIG. 15).

  When the value of the distance D between the data to be read was changed to 425 points, the reading position shifted in the opposite direction and became inappropriate. However, the reading range did not deviate from the potential data. In any case, there is a problem in the timing control accuracy of the measuring apparatus, and the periodicity of the recorded surface potential data has been disturbed. Therefore, the method based on the periodicity of the data has a problem in reading.

It is a figure which shows the example of the binarization data with respect to the general signal which is not limited to electric potential data. 2A and 2B are diagrams illustrating a first embodiment of the present invention, where FIG. 1A is a layout of a photoreceptor sensitivity characteristic evaluation apparatus, and FIG. 2B is a diagram illustrating an example of data obtained from the photoreceptor sensitivity characteristic evaluation apparatus. It is a figure which shows the example of the process timing of the photoconductor sensitivity characteristic evaluation apparatus in said 1st embodiment. It is a figure which shows the example at the time of producing | generating binary data from recorded data in the said 1st embodiment. It is a figure which shows the search of the position of the rising (falling) of binary data in the second embodiment. It is a figure which shows the process flowchart of a data reading in said 2nd embodiment. It is a figure which shows the example of the data range read by the reading start position and average value in 3rd embodiment. It is a figure which shows the example of the reading normal end in 3rd embodiment. It is a figure which shows the example of a measurement of a photoreceptor sensitivity characteristic in the 3rd embodiment. It is a figure which shows the example of the data without periodicity in the same 4th embodiment. It is a figure which shows the example of the recorded electric potential data and binarization in the fifth embodiment. It is a figure which shows the example of an electric potential reading start in the same 5th embodiment. It is a figure which shows the example of a reading normal end in the same 5th embodiment. It is a figure which shows the example of a periodic reading method start as a comparison in said 5th embodiment. It is a figure which shows the example of a periodic reading method completion | finish as a comparison in said 5th embodiment.

Explanation of symbols

1 Photosensitive drum (OPC)
2 Charger (CH / Grid)
3 Static eliminator (QL)
4 First surface electrometer probe (VD)
5 Second surface electrometer probe (VL)
6 Polygon mirror

Claims (2)

A charger for charging a rotatable photoconductor ;
An exposure device for writing image information on a charged photoreceptor surface to form an electrostatic latent image;
A probe for measuring the surface potential of the formed electrostatic latent image;
A discharger for erasing an electrostatic latent image on the surface of the photoreceptor,
A substantially square-wave-shaped potential signal obtained by measuring the surface of the photoconductor on which the electrostatic latent image is formed while sequentially changing the exposure energy with the exposure device while rotating is obtained by the probe. A signal processing device for A / D converting and storing ;
Square in the potential signal on the basis of a predetermined threshold from said generally potential signal of a square wave shape is recorded on the signal processing device generates binary data, are recognized on the basis of the binary data order of appearance of waves, the rise start point, the falling end point, reading the potential level between the rise start point and the falling end point of each square wave of the voltage signal automatically, based on the potential level read the And an information processing device that outputs a potential characteristic of the photosensitive member. The photoconductor characteristic evaluation apparatus according to claim 1, wherein the information processing apparatus outputs a relationship between the exposure energy and the potential of the photoconductor surface after exposure based on the automatically read potential level.

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