JP3142323B2 - Charge potential measurement method and charge removal potential calculation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a potential calculating technique applied to a charger, a static eliminator, a transfer unit, a separator and the like using corona discharge. INDUSTRIAL APPLICABILITY The present invention can be applied to calculation of the charged potential of an electrophotographic apparatus (copier, various printers) using corona discharge, ionography, a corona motor, and other recording apparatuses.

[0002]

2. Description of the Related Art In a conventional surface voltmeter, an error occurs in a measured value depending on a distance from a surface to be measured. For example, a TREK company uses a device for distance compensation and a surface potential calculation method. I have. FIG. 9 is a schematic diagram showing an example of a method for measuring and calculating a charged potential by a conventional method. In this example, the charging potential of a photosensitive dielectric (photoconductor 107) measured by a charger 101 often used in an electrophotographic system called a scorotron is measured. Charger 101
Has a cylindrical casing 102 and a discharge wire 103 stretched at the center thereof. The cylindrical casing 102 is partially grounded. A predetermined DC voltage 105 is applied to the discharge wire 103, and a charge is given to the photoconductor 107 by corona discharge as is known. The photoreceptor 107 is formed by forming a photoconductive layer on a conductive base 108 such as aluminum, and is rotated at a constant speed.

In such a configuration, the surface potential of the photoconductor 107 is measured by the probe 1 connected to the surface voltmeter 110.
09 is brought closer to the vicinity of the surface of the photoconductor 107 and measured. However, in general, the surface electrometer 11
Since the measured value of 0 depends on the distance between the probe 109 and the surface of the photoconductor 107, a surface potential calculation method for compensating for a change in the distance is required.

[0004]

However, even if such distance compensation is performed, the spatial resolution is not less than 100 μm and the temporal resolution is not more than 1 msec.
It was extremely difficult. Furthermore, it has been difficult to simultaneously measure the space charge due to corona discharge, the surface charge of the photoconductor, and the surface potential. In order to solve this problem, one of the inventors of the present application proposed a method of analyzing the corona ion field, and reported and presented it to the Institute of Electrostatics (discharge simulation of a corona charger for electrophotography. Lecture Paper '90 (1990.10) 16p C2, and discharge simulation of corona charger for electrophotography. Journal of the Institute of Electrostatics, 14 , 6 (1990) 494-502). These are methods for simultaneously analyzing a basic physical equation of corona discharge, that is, a Poisson equation relating to an electric field and a continuous equation of positive or negative ions.

Further, the present applicant has already proposed a method of calculating a charged potential by performing an analysis in consideration of movement of a dielectric and loss of charge due to resistance inside the dielectric (refer to a corona discharge device). Numerical simulation JAPAN PHARDOPY'91 sponsored by the Institute of Electrophotography and Japanese Patent Application No. 3
-105624). Although the proposed method can track the behavior of the original corona discharge device with high accuracy and a variety of geometric shapes and physical conditions, it has a drawback that it requires a lot of calculation time because of the principle approach. .
In particular, this problem is important in calculating a static elimination potential by applying an alternating current. This is because the applied voltage changes with time in the AC application process, so that it is not possible to use an implicit method to increase the time step.

SUMMARY OF THE INVENTION An object of the present invention is to greatly reduce the calculation time of a large number of calculations under various conditions in the calculation of the charging and discharging potentials. Another object of the present invention is to make it possible to calculate the charging potential of a charger or a static eliminator before actually producing the charger or the static eliminator. Further, as another object of the present invention, there is a case where the calculation time in the calculation of the charging and discharging potential is significantly reduced by an experimental method.

Another object of the present invention is to perform a high-speed calculation of a static elimination potential of a corona discharge static eliminator by applying an alternating current. Another object of the present invention is to provide a method capable of accurately calculating the potential of a dielectric surface.

[0008]

According to the first aspect of the present invention,
In calculating the charging potential of the dielectric by the charger or static eliminator using corona discharge, a table of the ion current density on the dielectric with respect to the potential difference between various points of the dielectric and the corona discharge wire is shown. To create, from the potential difference between the potential of the dielectric surface and the corona discharge wire, calculate the amount of surface charge accumulated on the dielectric using the table,
Each step of calculating potentials at various positions on the dielectric based on the calculated surface charge on the dielectric is used.

According to a second aspect of the present invention, in the method of calculating a charging potential according to the first aspect, the ion current density table is formed on the dielectric with respect to a potential difference between the dielectric and the corona discharge wire. It is characterized by numerically solving the Poisson equation for the electric field and the continuity equation for positive or negative ions, which describes the corona discharge. According to a third aspect of the present invention, in the method of calculating a charging potential according to the first aspect, when creating the ion current density table on the dielectric with respect to a potential difference between the dielectric and the corona discharge wire, A current measuring electrode is arranged at a position, a potential difference between the dielectric and the corona discharge wire is changed, and a current flowing through the current measuring electrode is measured.

According to a fourth aspect of the present invention, in the calculation of the static elimination potential of the dielectric by the static eliminator using the AC applied corona discharge, the steps of the first aspect are alternately used. The invention according to claim 5 is the invention according to claim 1.
The method according to claim 1, wherein
After the charging potential on the dielectric is obtained by the steps of (1) and (2), the charging potential is further obtained through the steps of (1) and (2).

[0011]

According to the first aspect of the present invention, the potential difference Δ between the potential at various positions on the surface of the dielectric and the corona discharge wire.
With respect to V, the ion current J to the dielectric is calculated or experimentally set in advance in an ion current density table (hereinafter, this table is referred to as a ΔV-J table), so that a large number of ions under various conditions can be obtained. The calculation time for each calculation can be greatly reduced.

According to the second aspect of the present invention, ΔV−
As a method of creating the J table, a numerical calculation method presented by one of the present inventors at the Electrostatics Society of Japan was used, whereby the calculation of the charging potential of the charger or the static eliminator was actually performed to prepare the charger or the neutralizer. Before possible. According to the third aspect of the present invention, as a method of creating a ΔV-J table, an electrode electrically insulated from a conductive material (for example, a jig drum made of aluminum) is disposed at a position of a dielectric. , By measuring the current flowing through the electrode.

According to the fourth aspect of the present invention, the analysis steps described in the first aspect are repeatedly and alternately performed,
Significant reduction in calculation time can be achieved. According to the fifth aspect of the present invention, after calculating the electric potential of the dielectric surface by the steps of the first and second aspects, the ΔV-J table is created again based on the electric potential to store the electric charge. Calculate the behavior of

[0014]

Embodiments of the present invention will be described below. Regarding the configuration and operation of the present invention, first, an example in which a Poisson equation relating to an electric field describing a corona discharge and a ΔV-J table created by numerically solving a continuity equation of positive or negative ions is used. explain.

FIG. 1 is a block diagram of an apparatus for applying a charge to a photosensitive member by a cylindrical corotron charger. The cylindrical corotron charger 1 includes a cylindrical casing 2 at a predetermined distance from a cylindrical photoreceptor 7.
Has a structure in which a discharge wire 3 is stretched at the center.
The cylindrical casing 2 is partially grounded. A predetermined DC voltage 5 is applied to the discharge wire 3, and a charge is given to the photoconductor 7 by corona discharge as is known. The photoconductor 7 is formed by forming a photoconductive layer on a conductive substrate 8 such as aluminum, and is rotated at a constant speed.

FIG. 8 is a block diagram of a measuring apparatus for measuring a charged potential according to the present invention. This measuring device includes a program storage unit 32 in which various programs to be described later are stored in a control unit 30 that performs a predetermined calculation, a geometric shape of the casing 2, a dielectric constant of the photoconductor 7, an electric conductivity, a moving speed, and the like. Calculation setting condition storage unit 34 in which calculation setting conditions (parameters) are stored, and ΔV- in which ΔV-J table information is stored.
The configuration is such that a J-table memory 36 and a calculated potential memory 38 for storing the calculated potential are connected. An input unit 40 such as a keyboard is connected to the calculation setting condition storage unit 34 and the ΔV-J table memory 36 so that calculation setting conditions (parameters) or ΔV-J table information by actual measurement can be input from the input unit 40. Has become.

Next, a procedure for creating a ΔV-J table will be described. First, the measurement device shown in FIG.
The applied voltage of the discharge wire 3 supplied by the power supply 5 and the dielectric constant, electric conductivity, and moving speed of the photosensitive member 7 which is a kind of dielectric are input. Using the input values and the program stored in the program storage unit 32, for the gas region where corona discharge occurs, the above-mentioned equation of the electrostatic field and the equation of the electric conduction or the charge transport by the transfer of the electric charge are calculated. solve.

At this time, since the purpose is to create a ΔV-J table, a potential is specified for the position where the photoconductor 7 exists. Normally, the voltage is set to 0 V in the first ΔV-J table. That is, in this case, it corresponds experimentally to placing a conductive (for example, aluminum) jig drum in place of the photoconductor 7. In this way, when the voltage applied to the discharge wire 3 is variously changed by setting a program, the ion current density flowing into each point of the photoconductor 7 can be obtained. From this table, the ion current value J is obtained using the position on the photoconductor 7 and the potential difference ΔV between the discharge wire 3 and the photoconductor 7 as parameters.

FIG. 2 is a graph schematically showing the ΔV-J table information thus created. For example, the current values J at points A at the left end of the casing in FIG. 1, B at the position immediately below the discharge wire, and C at the right end of the casing pass through the points indicated by A, B, and C in FIG. X indicating
It is given as the intersection of a plane perpendicular to the axis and the ΔV-J curve 11 stored in the ΔV-J table memory 36.

FIG. 3 shows how the actual charging process is traced.
In the flowchart of FIG. First, a ΔV-J table is created on the assumption that the potential on the photoconductor 7 is a certain value (step 201). Next, an initial surface charge of the photoreceptor 7 is set (step 202), and taking this charge into account, the potential distribution between the space including the charger or the static eliminator and the area within the photoreceptor 7 is calculated by Poisson's equation relating to the electric field. To calculate the potential on the photoconductor 7 (step 204). By searching the ΔV-J table from the potential difference ΔV between the potential and the discharge wire 3, the ion current density J at each point on the photoconductor 7 is obtained. As a result, the surface charge on the photoconductor 7 is calculated. Yes (step 205).

Next, the surface charge on the photoreceptor 7 is solved by a charge transfer equation corresponding to the moving speed of the photoreceptor 7 (step 2).
06), a charge distribution at a certain time is obtained, and the potential of the photoconductor 7 is calculated from the charge distribution (step 207).
By continuing the calculation until the required time is reached (step 203), the charged potential of the photoconductor 7 can be obtained (loop from step 203 to step 207).

The above-described method of calculating the charging potential is effective because the voltage applied to the corona discharge wire 3 is 4 to 7 kV, whereas the charging potential is usually 1 kV or less. It is considered that the change of the electric field distribution inside the charger or the static eliminator due to the above is not severe.

In FIG. 3, the step which takes the longest time in each of the calculation blocks from step 201 to step 207 is the step 201. Therefore, the voltage applied to the discharge wire 3, the initial surface charge of the photoconductor 7, the rotation speed of the photoconductor 7,
If you only want to change the dielectric constant , electrical conductivity, etc.,
The calculation time can be greatly reduced by obtaining the ΔV-J table.

As another embodiment of the present invention, ΔV−J
FIG. 4 shows a configuration when the table is obtained experimentally. Here, reference numeral 12 denotes a conductive jig drum, which is grounded. On the jig drum 12, an insulating base 15 and a current measuring electrode 14 formed on the insulating base 15 are provided.
A current measurement probe 13 is provided. This current measuring probe 13 is also grounded. The current from the current measuring probe 13 is connected to the ammeter 16 so that the ion current due to corona discharge can be measured, and the ion current density J can be easily obtained therefrom. That is,
The ΔV-J table can be obtained by changing the voltage applied to the discharge wire 3 and changing the position of the current measuring probe 13 on the photoconductor 7 in various ways.

Of course, a large number of probes 13 and the photosensitive member 7
If it is grounded on the top, the ΔV-J table can be created more quickly. This ΔV-J table is input from the input unit 40 of FIG.
By storing the data in the J table memory 36 in advance and storing it in step 20 in the flowchart of FIG.
1 can be performed. Thus, the experimentally determine the [Delta] V-J table, compared to the method of obtaining by calculation as the embodiment has the advantage that it is not necessary to the large-scale calculation.

The following embodiment is an example in which the above method is applied to an AC applying corona neutralizer. FIG. 5 shows the shape of the square corotron static eliminator and the calculation grid for corona discharge calculation used for creating the ΔV-J table. In the case of Corona Wire AC 4.2 kV, the casing is 0
V, the photosensitive member moving speed is 94 mm / sec. A, B, C, D, E, and F in the figure indicate positions around the casing, respectively. The calculation steps within the range of reference numeral 21 shown in FIG. 3 (from step 202 to step 207) may be repeatedly used based on the calculated grid. However, since the AC is applied, it is necessary to make the time interval of the calculation sufficiently shorter than the cycle of the AC, and to pay attention to the calculation in step 205 that the voltage applied to the discharge wire 3 changes due to the AC.

FIG. 6 shows the change over time of the potential at each position of the photoconductor 7 due to the AC applied corona discharger calculated in this way. Although there is a voltage change of several tens of volts at the point D at the center of the static eliminator, almost no voltage change can be seen at points A and B where the static eliminator has exited. FIG. 7 shows a comparison between the result obtained by the present method for calculating the neutralization potential indicated by the point 実 験 and the experimental value indicated by the point ＋. Here, calculation is used as the ΔV-J table. As can be seen from the figure, the experiment and the value obtained by the proposed method showed extremely good agreement, and it was found that the proposed method was effective for the development of a static eliminator.

In the above embodiment, the ΔV-J table is obtained only once at the beginning, but the potential distribution on the photosensitive member surface assumed at the time of creating this table is different from the final potential distribution. Quite different. Although this difference is small compared to the magnitude of the voltage applied to the discharge wire, if it is necessary to more accurately determine the final charging potential, the photoconductor obtained after passing through each step of FIG. The ΔV-J table may be created again based on the charged potential.

Further, in the above embodiment, the charging potential and the discharging potential of the charger and the charge eliminator using the corona discharge have been described. However, the present invention is similarly applied to the calculation of the transfer device and the separator using the corona discharge. be able to. Further, the present invention can be similarly applied to the measurement of the potential of various dielectrics without being limited to the photoreceptor.

[0030]

According to the first aspect of the present invention, since the .DELTA.V-J table is prepared in advance by an experiment or a calculation method, the potential difference .DELTA.V between the surface of the photosensitive member and the discharge wire is controlled. As a result, the ion current J can be obtained, and the charging potential of the charger or static eliminator can be calculated at high speed.

According to the second aspect of the present invention, in the charging potential calculating method according to the first aspect, since the ΔV-J table is obtained by calculation based on the basic physical equation of corona discharge, the charging device or the charging device is actually removed. It becomes possible to predict the charged potential of an electric appliance before producing it. According to the third aspect of the present invention, the charge potential calculation method according to claim 1, wherein, in order to determine experimentally [Delta] V-J table, it is not necessary to the large-scale calculation.

According to the fourth aspect of the present invention, it is difficult to solve the physical equation (Poisson's equation relating to the electric field and the continuity equation of positive or negative ions) relating to the corona discharge. In the prediction of the static elimination potential by the static eliminator, the ion current is calculated while obtaining the ion current from the ΔV-J table.

According to the fifth aspect of the present invention, since the ΔV-J table is re-created based on the result of the calculation of the charging potential in the first step of the first aspect, the calculation is made more accurate. The charging potential can be calculated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus for applying a charge to a photoconductor by a cylindrical corotron charger.

FIG. 2 is a diagram schematically showing a ΔV-J table.

FIG. 3 is a flowchart of a process according to the embodiment.

FIG. 4 is a diagram showing a configuration in a case where a ΔV-J table is experimentally obtained.

FIG. 5 is a diagram showing a calculation grid for corona discharge calculation used for creating a ΔV-J table in an AC applied corona discharger.

FIG. 6 is a graph showing a temporal change in the potential of each position of the photoconductor by the AC applying corona discharger.

FIG. 7 is a graph showing a comparison between a result obtained by the method for calculating a static elimination potential and an experimental value in an AC applying corona static eliminator.

FIG. 8 is a block diagram of a measuring device for measuring a charging or discharging potential according to the present invention.

FIG. 9 is a schematic diagram showing an example of a method for measuring and calculating a charged potential according to a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical corotron charger 2 Casing 3 Discharge wire 5 DC voltage 7 Photoconductor 30 Control part 32 Program storage part 34 Calculation setting condition storage part 36 ΔV-J table memory 38 Calculation potential memory 40 Input part

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-32782 (JP, A) JP-A-64-57276 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 29/12 G03G 5/00 G03G 15/00 G03G 15/02 G03G 21/00 JICST file (JOIS)

Claims (5)

(57) [Claims] In a calculation of a charging potential of a dielectric by a charger or a static eliminator using a corona discharge, a calculation is performed on the dielectric with respect to a potential difference between various points of the dielectric and a corona discharge wire. To create a table of ion current density of, from the potential difference between the potential of the dielectric surface and the corona discharge wire, calculate the amount of surface charge accumulated on the dielectric using the table, the calculated A charging potential calculation method, comprising: calculating potentials at various positions on the dielectric based on the amount of surface charge on the dielectric. 2. The method according to claim 1, wherein the corona discharge is described in creating the ion current density table on the dielectric with respect to the potential difference between the dielectric and the corona discharge wire. A charging potential calculation method characterized by numerically solving a Poisson equation relating to an electric field and an equation of continuity of positive or negative ions. 3. A method according to claim 1, wherein said ion current density table is formed on said dielectric with respect to a potential difference between said dielectric and said corona discharge wire. A charging potential calculation method comprising: disposing a measurement electrode; changing a potential difference between the dielectric and the corona discharge wire; and measuring a current flowing through the current measurement electrode. 4. A method for calculating a static elimination potential according to claim 1, wherein the steps of (1) and (2) are alternately used in the calculation of the static elimination potential of the dielectric by the static eliminator using the AC applied corona discharge. 5. The charging potential calculation method according to claim 1, wherein the charging potential on said dielectric is determined by each of the steps (1) and (2) described in (1). A charging potential calculation method, wherein a charging potential is obtained through each step.