JPH07271153A - Ozoneless and contactless electrostatic charging method and device therefor - Google Patents

Abstract

PURPOSE:To realize a contactless electrostatic charging method which is capable of executing uniform electrostatic charging in spite of presence of unequalness in a discharge source and does not generate ozone and for which gap accuracy is not so much demanded and a device therefor. CONSTITUTION:Grid electrodes 2 are arranged in parallel with a planar corona discharge electrode 1 consisting of a conductive layer 1a and a semiconductive layer 1b via a microspacing by a spacer 4. A member 3 to be electrostatically charged, such as OPC photosensitive drum, is arranged in approximately parallel with these grid electrodes 2. This member 3 to be electrostatically charged is formed with a dielectric layer 3a on the conductive layer 3b. This conductive layer 3b is grounded and voltage slightly lower than the target electrostatic charge potential is impressed to the grid electrodes 2 to generate an electric field below the electric field at which the ozone is generated between the grid electrodes 2 and the member 3 to be electrostatically charged. The voltage to generate the electric field at which an electron multiplying effect is generated is impressed between the corona discharge electrode 1 and the grid electrodes 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface of an object to be charged such as a photoconductor, which is an image carrier in an image forming apparatus such as a copying machine, a printer or a facsimile apparatus, which uses an electrophotographic system or an electrostatic recording system. TECHNICAL FIELD The present invention relates to an ozoneless non-contact charging method and apparatus for uniformly charging without generating electricity.

[0002]

2. Description of the Related Art Since an electrophotographic copying machine was first put into practical use, a corotron or scorotron charging system is used in which charging is performed by almost non-contact corona discharge in order to charge the surface of a photoconductor which is an image carrier. Vessels have been used.
In particular, the scorotron charger automatically selects unevenness in the potential by selectively moving corona ions between the grid electrode and the body to be charged to a location with a low potential, even if the discharge source (corona wire) causes uneven discharge. It has a very excellent feature that it is solved.

However, these corona dischargers are
There is a problem in that a high voltage of 5 to 10 Kv is required and ozone is generated due to discharge. Therefore, an image forming apparatus such as a copying machine usually has to be equipped with an ozone filter. Therefore, in recent years, a contact charging method has been used in which a charging roller, a charging brush, a charging blade or the like to which a voltage is applied is brought into direct contact with a member to be charged for charging. This contact charging is caused by a combination of air discharge (corona discharge) in the air gap, charge injection and frictional charge in the contact portion, and in practice air discharge is dominant.

The contact charging has a merit that the generation of ozone is small and the applied voltage is lower than that in the case of corona discharge, and that it may be 1 to 2 Kv, but it has the following problems. (1) The structure of the charger is more complicated than that of the corona charger, and the cost is higher. (2) Since conductive carbon black is dispersed in high resistance rubber to make a charging roller, the resistance varies partially due to uneven resistance, and the resistance of the roller changes due to environmental changes such as humidity. , The charging characteristics change.

(3) In the image forming apparatus, since the charging roller is in contact with the photosensitive drum, the contact surface is soiled by the cleaning residual toner, resulting in uneven charging. (4) As a countermeasure, it is necessary to clean the charging roller, but if the cleaning blade is left under pressure contact, it will have an adverse effect. (5) If there is a pinhole on the photoconductor drum, an overcurrent will flow there, and there will be no horizontal line image or it will be completely black. Alternatively, a part of the rubber roller flies and is damaged.

Then, returning to the non-contact method, a charging device for corona discharge has been developed in which a semi-conductive flat plate electrode is arranged close to the photoconductor as shown in, for example, Japanese Unexamined Patent Publication No. 5-107866. ing. This charging device performs non-contact charging from a distance of only about 0.2 mm, not from a distance of 10 mm from the charged body. According to this charging method, since it is non-contact as in the case of the conventional corona discharge, it has an advantage that it is not affected by defective cleaning or pinholes of the photoconductor.

[0007]

However, this charging device is not suitable for corona discharge that is 10 mm away from the body to be charged,
Unlike the case of contact charging of 0 mm, it is necessary to accurately maintain a small gap of about 0.2 mm. For example, in the case of corona discharge or contact charging, there is no problem even if the gap between the centers is deviated by 0.1 mm, but in this case, there is a drawback that a large charging potential unevenness is immediately caused, which results in uneven density of copy or print. .

For example, if 2 Kv is applied at 0.2 mm, it will be charged about 600 v, but if it becomes 0.1 mm, it will be 900
If v becomes 0.3 mm, it becomes 100 v. To improve this point, the gap should be widened from the beginning. For example, if the gap is expanded to 1.0 mm, the required applied voltage will be 10 Kv, which is proportionally high, and this charging The advantages of the method are lost.

The present invention has been made in view of the problems of the various conventional charging methods and devices thereof, and can uniformly charge even if the discharge power source is uneven like a scorotron charger. Moreover, it is an object of the present invention to realize a non-contact charging method and an apparatus thereof, in which ozone is not generated and gap accuracy is not so required.

[0010]

In order to achieve the above object, the ozone-less non-contact charging method according to the present invention sets the electric field in the space adjacent to the charged body to be equal to or lower than the electric field generated by ozone, and An object to be charged is charged by forming an electric field in which an electron multiplication effect occurs in a space adjacent to a space in which an electric field equal to or lower than the ozone generating electric field is formed.

Further, a conductive layer or a semi-conductive layer formed on the conductive layer is used as a corona discharge electrode, and an electron multiplying action is provided in a space between the discharge electrode and a grid electrode placed in parallel with a minute gap. To form a generated electric field, between the grid electrode and a moving or fixed charged object placed through a predetermined gap, an electric field equal to or less than the electric field generated by ozone is formed, and the discharge electrode and The positive or negative ions generated between the grids are directly converted, or the electrons generated therein are converted into negative ions between the grid and the charged body, and the charged body is charged with the positive or negative ions. Good to do.

Alternatively, a conductive layer or a semiconductive layer formed on the conductive layer is used as a corona discharge electrode, and a space between the discharge electrode and a counter electrode having an opening placed in parallel through a minute gap. To form an electric field in which electron multiplying occurs, and to make the charged potential of the charged body constant between the counter electrode and the charged or moving body which is placed via a predetermined gap. The grid electrode is arranged to form an electric field below the electric field generated by ozone in the space between the counter electrode and the body to be charged, and positive or negative ions generated between the discharge electrode and the counter electrode are generated. The electrons generated there may be directly converted into negative ions between the counter electrode and the charged body, and the charged body may be charged with the positive or negative ions.

In the ozoneless non-contact charging device according to the present invention, a corona discharge electrode composed of a conductive layer or a semi-conductive layer formed on the conductive layer, and a grid placed in parallel with the corona discharge electrode via a minute gap. An electrode, a power supply for applying a voltage for forming an electric field that causes an electron multiplying effect in the gap between the discharge electrode and the grid electrode, and the grid electrode and the electrode are placed through a predetermined gap. To form an electric field equal to or lower than the electric field generated by ozone between the charged or moving object and to apply a grid voltage to the grid electrode such that the surface potential of the charged object reaches a target value. With a power supply

Alternatively, a corona discharge electrode made of a conductive layer or a semiconductive layer formed on the conductive layer, a counter electrode having an opening placed in parallel with the discharge electrode via a minute gap, and the gap. A power supply for applying a voltage for forming an electric field in which an electron multiplication effect is generated between the discharge electrode and the counter electrode, and a moving or fixed object placed through a predetermined gap with respect to the counter electrode. Between the charged body and a grid electrode arranged in parallel with the counter electrode through a minute gap, and to form an electric field below the electric field generated by ozone in the space between the counter electrode and the body to be charged. It is more preferable to include a power supply for applying a voltage such that the surface potential of the body to be charged reaches a target value to the counter electrode and the grid electrode, respectively.

[0015]

According to the ozoneless non-contact charging method of the present invention, in the gap between the corona discharge electrode and the member to be charged, a strong electric field in which electron multiplication is generated and a weak electric field less than or equal to the electric field in which ozone is generated are two steps. By superimposing the equal electric fields of the above, the ozone generation electric field can be almost eliminated, and the generation of ozone can be suppressed to a very low level. Further, it is possible to charge the charged body with the ions generated by the electron multiplication effect.

Further, by controlling the applied voltage using the grid electrode or the grid electrode and the counter electrode,
Various unevenness of the discharge source and the body to be charged does not occur, and uniform charging is always possible under various conditions. Further, the ozoneless non-contact charging device of the present invention can carry out the ozoneless non-contact charging method described above, and the gap between the corona discharge electrode and the body to be charged is not extremely small, so that the management of the gap is easy. Moreover, since the structure is simple, it can be provided at a low cost and the size can be easily reduced.

[0017]

Embodiments of the present invention will be described below with reference to the drawings, but prior to that, the mechanism of corona discharge and ozone generation will be described. This facilitates understanding of the ozoneless non-contact charging method according to the present invention.

"The theory of corona discharge and ozone generation" Although the mechanism of corona discharge is not completely understood,
It can be understood as follows. An example will be described in which a corotron charger, which is a typical conventional corona charger, performs negative charging. As shown in Fig. 3, the corotron charger has 8
Corona wire 21 made of 0 micron tungsten wire
Is placed in the air, a metal plate 22 (generally referred to as a “shield case”) 22 is placed on the top and the left and right of it 10 mm apart, and the corona wire 21 is also 10 m away from the lower opening.
The charged body 23 is placed at a distance of m.

The member to be charged 23 is an OPC photosensitive drum or belt, and is composed of a dielectric layer 23a and a conductive layer 23b, and the conductive layer 23b is normally grounded. When a high voltage of -4 Kv or more is applied to the corona wire 21 of this charger, an unequal electric field is formed around the corona wire 21, which becomes strong near and weak at a distance. Consider the space of this unequal electric field divided into three regions according to the strength of the electric field. That is, from the vicinity of the corona wire 21 as shown in FIG.
The areas are B and C.

<A region (electron multiplying region)> The A region is a portion where the electric field is 10 ⁷ v / m or more and is a cylindrical space around the corona wire 21 with a radius of about 0.1 mm. It is called a region. (Specific numbers are given for easy understanding, but they are not absolute values). In the A region, a large amount of electrons and positive ions are generated by the action of α, β, γ described below.

First, the "α action" will be described with reference to FIGS. FIG. 5 is an explanatory diagram showing that electrons and positive and negative ions are present in the air due to cosmic rays when an electric field is not formed between the corona wire 21 and the charged body 22. Normally, there are about 1000 electric charges / cm ³ ionized by cosmic rays in the air. The circles in the figure indicate the existence of molecules and ions, and the symbols in them indicate their types. O ₂ is an oxygen molecule, N ₂ is a nitrogen molecule, e is an electron, + is a positive ion, − is a negative ion. Ions are shown respectively.

From this state, when an electric field is applied between the corona wire 21 and the body 22 to be charged by the DC power source E as shown in FIG. 6, positive and negative ions and electrons (these are called charges) move according to Coulomb's law. Begin to. When the electric field is sufficiently strong, the accelerated electron e obtains large kinetic energy before colliding with other air molecules, and when colliding with a neutral air molecule (oxygen molecule O ₂ or nitrogen molecule N ₂ ), the electron Strike out e.

That is, one electron e is two electrons e
And increase to one positive ion +. This is repeated,
A large amount of electric charge is generated from a small amount of electric charge. This is also called an electron doubling action (α action), which is also called an avalanche effect. Although the distance is short, the mean free path of electrons is about 0.2 micron, so one electron is 2
^It should increase by ⁵⁰⁰ (cannot be calculated, 2 ²⁰⁰ = 1.6 × 10 ⁶⁰ ). However, since positive and negative charges are recombined immediately, the actual surviving charges are 1000 at 10 mm and 10 at 0.1 mm for the first electron.
It is about an individual.

Next, the "β action" will be described with reference to FIG. The positive ions + accelerated by the electric field collide with neutral molecules (oxygen molecule O ₂ or nitrogen molecule N ₂ ) as shown in FIG. 7, and become two positive ions + and one electron e. This is the β action, and the β action also produces an electron e although the probability is low.

Finally, the "γ action" will be described with reference to FIG. When the remaining 10 positive ions + generated by the above-mentioned α action collide with the corona wire 21, several tens of electrons e are knocked out. This is the γ action, and this is repeated to generate a large number of electrons e and positive ions + in a short time.

<B Region (Ozone Generation Region)> Next, referring to FIG.
The electron e that has left the area A enters the area B, and here, even if it is accelerated by an electric field, it cannot collide with a neutral molecule and obtain sufficient energy to knock out an electron. However, as shown in FIG. 9, it strikes a neutral molecule such as oxygen molecule O ₂ and activates it. That is, the oxygen molecule O ₂ is replaced by two oxygen atoms O 2.
Can be divided into This oxygen atom O is an oxygen molecule O ₂
Then, the following chemical reaction occurs to form ozone O ₃ .

O + O ₂ + M → O ₃ + M (M = O ₂ or N ₂ ) The electric field in this B region is 1 × 10 ⁶ v / m or more and 1
It is about 10 ⁷ v / m or less, and the range seems to be within 0.5 mm apart from the corona wire 21 by 0.1 mm or more.

<C region (ion generation region)> The electric field is 1 × 1 in the space outside the region B shown in FIG. 3 up to the grounded shield case 22 and the electrically conductive layer 23a of the body 23 to be charged.
In the C region of 0 ⁶ v / m or less, the electron e is accelerated by the electric field and the neutral molecule (oxygen molecule O ₂
Or, even if it collides with the nitrogen molecule N ₂ ), there is not enough energy to activate it and it is adsorbed by the neutral molecule to form negative ions. This negative ion-is charged by a weak electric field 2
Move to 3 to charge it.

<Ozone-less charging> As can be seen from the above description, ozone is generated in the B region. Therefore, in order to realize ozoneless charging, it is sufficient to eliminate the B region.

FIG. 4 is an explanatory diagram of areas A, B and C of the electric field when contact charging is performed using a conventional charging roller. In this case, since only the area A where the charging roller 25 and the member to be charged 23 form a gap of several tens of microns is used, ozone is hardly generated. However, the charging roller 25 is composed of the conductive elastic layer 25a and the resistor layer 25b formed on the outer periphery thereof, and the resistor layer 25b is in contact with the dielectric layer 23a of the charged body 23. Various non-uniformities such as surface resistance, shape, composition, stains, etc. appear as uneven charging potentials.

An excellent method for obtaining a uniform potential even when the charging power source is uneven is a scorotron charger having a grid electrode, as is well known in the art. If a constant voltage is applied to the grid electrode stretched close to the charged body (1 to 2 mm), it will be charged even if there is uneven discharge or uneven thickness of the charged body. The potential of the body becomes almost uniform by the voltage applied to the grid.

Therefore, the ozoneless non-contact charging method according to the present invention prevents the generation of ozone by eliminating the electric field for ozone generation while using non-contact corona discharge. Further, by applying a voltage to the grid electrode arranged close to the body to be charged, uniform charging is possible. However, in an unequal electric field in which the strength of the electric field continuously changes, it is impossible to remove only a part of the electric field, and therefore an equal electric field is required. Therefore, the B region can be removed by superimposing the strong equal electric field corresponding to the A region and the weak equal electric field corresponding to the C region.

<First Embodiment> FIG. 1 is a schematic sectional view of a first embodiment of an ozoneless non-contact charging device according to the present invention. In this charging device, a grid electrode 2 is arranged in parallel with a flat corona discharge electrode 1 with a minute gap formed by a spacer 4, and the grid electrode 2 is arranged substantially parallel to the grid electrode 2 as in a conventional scorotron charger. An object to be charged 3 such as an OPC photosensitive drum or a belt is arranged in. This charged body 3 has a dielectric layer 3a formed on a conductive layer 3b, and the conductive layer 3b is grounded so that the grid electrode 2 receives a DC power source E.
_{By 1} , a voltage slightly lower than the target charging potential (-0.8 Kv in this example) is applied.

The corona discharge electrode 1 may be the conductive layer 1a only, but a semiconductive layer may be provided on the surface of the conductive layer 1a facing the charged body 3. Then, a voltage (-2.0 Kv in this example) for forming an electric field corresponding to the area A in which the electron multiplying action occurs in the gap between the conductive layer 1a of the corona discharge electrode 1 and the grid electrode 2, A DC power supply E ₂ is applied between both electrodes.

The gap between the grid electrode 2 and the body 3 to be charged is 2.0 mm, which is an electric field below the electric field in the C region, that is, the electric field generated by ozone. Of course, there is an electric field corresponding to the B region at the boundary, but the generation of ozone is extremely small because it is a very thin layer. Then, the positive or negative ions generated between the corona discharge electrode 1 and the grid electrode 2 are directly changed, or the electrons generated there are changed to negative ions between the grid electrode 2 and the charged body 3 to be charged. The dielectric layer 3a of the body 3 is charged with its positive or negative ions.

As described above, by superimposing the uniform electric fields of two levels, the ozone generation electric field can be almost eliminated and the generation of ozone can be suppressed to a very low level. Further, by controlling the grid electrode 2, uniform charging can be performed regardless of various irregularities of the corona discharge electrode 1 and the charged body 3.

Here, the procedure for implementing this embodiment by modifying the scorotron charger of the existing electrophotographic copying machine will be described. 1) Remove the scorotron charger from the copier. 2) Remove the corona wire from the scorotron charger. 3) Place two 0.1 mm thick polyester films (trade name Luminor) on the grid electrodes on both sides of the scorotron charger, and fix them with an adhesive to form spacers 4.

4) On top of that, a width of 6 mm and a length of 200 m
m, 1 mm thick SUS (stainless steel) plate conductive layer 1a, low resistance urethane rubber semi-conductive layer 1b thickness 2 m
The corona discharge electrode 1 applied to m is stacked and fixed with the urethane surface facing down. As a result, the distance between the semiconductive layer (urethane rubber) 1b of the corona discharge electrode 1 and the grid electrode 2 is fixed at 0.2 mm. 5) Mount the modified charger on the original position of the copying machine. At this time, the gap between the grid electrode 2 and the charged body 3 is 2.
It becomes 0 mm.

Then, a voltage of -2.8 Kv is applied to the conductive layer 1a of the corona discharge electrode 1 and a voltage of -0.8 Kv is applied to the grid electrode by the DC power supplies E ₁ and E ₂ , respectively, and the copying machine is operated to charge the member to be charged. When the OPC photosensitive drum of No. 3 was charged and the surface potential thereof was measured at the position of the developing device, the average value was -902v, the maximum value was -910v, and the minimum value was -8.
It was 92 v, and a very uniform charging potential was obtained. Then, when copying originals of various images, it was possible to obtain even copies of all the images.

After continuously copying 100 sheets of A3 size paper, the air in the vicinity of the charger was sucked into a gas tech detector tube for ozone to measure the ozone concentration, which was 1 ppm or less. It was That is, when the present invention is carried out, the ozone filter used for the conventional scorotron charger is unnecessary.

The manufacturing cost of this charger is comparable to that of a scorotron, and the applied voltage is low, so that the high-voltage power source is inexpensive and the ozone filter is unnecessary. Compared with a contact charger using a charging roller, the manufacturing cost is about 1/2, and it is about 1/4 if the cleaning device and the contact / separation device required for the charging roller are not necessary. The width of the charger is about 1/4 of the scorotron charger and about 1 of the charging roller.
It can be / 2.

<Comparative Example 1 (Scorotron)> A similar test was carried out in a copying machine using a scorotron charger before modification. As a result, the uniformity of the potential and the uniformity of the copy image were at the same level as in the case of the above example. However, the ozone concentration was 1
It was over 00 ppm. (However, since the air inside the machine is exhausted to the outside after passing through the ozone filter, the ozone concentration outside the machine is much lower.)

Comparative Example 2 (Charging Roller) A similar test was conducted with a copying machine using a prototype charging roller (core metal 6 mm, urethane rubber layer 3 mm, applied voltage −1.6 Kv) instead of the scorotron charger. The ozone concentration is 1p
It was pm or less, but the charging potential was ± 30 with respect to the average value.
It was more than v. Especially, when a thin original having a uniform density was copied, the density unevenness was remarkable in that portion.

<Second Embodiment> In the above-described first embodiment of the present invention, the grid electrode 2 serves as both the counter electrode of the corona discharge electrode 1 and the grid electrode between the charged body 3 at the same time. Although it has been performed, both may be separated and independent counter electrodes may be provided. A second embodiment of the ozoneless non-contact charging device having such a configuration is shown in FIG.

In this embodiment, a counter electrode (second-stage grid electrode) 5 is placed on the first spacers 4 arranged at both ends of the grid electrode 2, and the thickness of the polyester film is set to 0. The corona discharge electrode 1 was placed via the spacer 6 of 2 mm 2. Then, the DC power supplies E ₁ , E
_When a voltage of −0.8 Kv is applied to the grid electrode 2, a voltage of −0.9 Kv to the counter electrode 5 and a voltage of −2.9 Kv to the discharge electrode 1 by ₃ , E ₂ , the charging potential of the surface of the charged body 3 is changed. The variation became even smaller.

[0046]

As described above, by carrying out the ozoneless non-contact charging method of the present invention, soft charging can be performed in a state where ozone is hardly generated. Further, by using the grid electrode or the grid electrode and the counter electrode, it is possible to always perform uniform charging even under conditions where various types of unevenness occur. Further, the ozoneless non-contact charging device of the present invention is for carrying out the above-mentioned ozoneless non-contact charging method, can be provided at low cost, and can be easily downsized.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an ozoneless non-contact charging device showing a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of an ozoneless non-contact charging device showing a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of A, B, and C regions of an electric field when a body to be charged is charged using a conventional scorotron charger.

FIG. 4 is an explanatory diagram of A, B, and C regions of an electric field when a member to be charged is charged by using a conventional charging roller.

FIG. 5 is an explanatory diagram of the existence of electrons and positive and negative ions due to cosmic rays in the air when an electric field is not formed between the corona wire and the body to be charged.

FIG. 6 is an explanatory view of α action in an A region when an electric field is formed between the corona wire and the body to be charged in FIG.

FIG. 7 is an explanatory view of β action.

FIG. 8 is an explanatory diagram of a γ action.

FIG. 9 is an explanatory diagram of C ozone generation similarly in the B region.

FIG. 10 is an explanatory diagram of ion generation in the same region C.

[Explanation of symbols]

1: Corona discharge electrode 1a: Conductive layer (SUS plate) 1b: Semi-conductive layer (urethane rubber) 3: Charged object (OPC photosensitive member) 3a: Dielectric layer 3b: Conductive layer 4, 6: Spacer 5: Counter electrode 21 : Corona wire 22: Shield case (metal plate) 23: Charged body 25: Charging roller E, E ₁ , E ₂ , E ₃ : DC power supply

Claims (5)

[Claims] 1. An electric field in a space adjacent to a body to be charged is set to be equal to or lower than an electric field generated by ozone, and a space adjacent to a space formed apart from the body to be charged and equal to or lower than the electric field for ozone generation is formed. And an ozoneless non-contact charging method characterized by forming an electric field in which an electron multiplying action occurs. 2. A conductive layer or a semiconductive layer formed on the conductive layer is used as a corona discharge electrode, and an electron multiplying action is provided in a space between the discharge electrode and a grid electrode placed in parallel with a minute gap. Is generated, and an electric field equal to or less than the electric field generated by ozone is formed between the grid electrode and a moving or fixed charged object placed through a predetermined gap, and the discharge electrode and Charge the positive or negative ions generated between the grids directly or by converting the electrons generated therein into negative ions between the grid and the charged body, and charge the charged body with the positive or negative ions. An ozoneless non-contact charging method characterized by: 3. A corona discharge electrode made of a conductive layer or a semi-conductive layer formed on the conductive layer, a grid electrode placed in parallel with the discharge electrode via a minute gap, and an electron multiplying effect in the gap. A power source for applying a voltage for forming an electric field generated between the discharge electrode and the grid electrode, and a charged or moving or fixed electrode that is placed through a predetermined gap with respect to the grid electrode and the electrode. A power source for applying a grid voltage to the grid electrode such that an electric field equal to or lower than an electric field generated by ozone is formed between the body and the surface potential of the charged body reaches a target value. Characteristic ozoneless non-contact charging device. 4. A conductive layer or a semiconductive layer formed on the conductive layer is used as a corona discharge electrode, and a space between the discharge electrode and a counter electrode having an opening placed in parallel through a minute gap. To form an electric field in which electron multiplying action occurs, and to make the charged potential of the charged body constant between the counter electrode and the charged or moving body that is placed through a predetermined gap. Of the grid electrode, to form an electric field below the electric field generated by ozone in the space between the counter electrode and the body to be charged, positive or negative ions generated between the discharge electrode and the counter electrode An ozoneless non-contact charging method, characterized in that electrons generated directly thereat are converted into negative ions between the counter electrode and the body to be charged, and the body to be charged is charged with the positive or negative ions. 5. A corona discharge electrode comprising a conductive layer or a semi-conductive layer formed on the conductive layer, a counter electrode having an opening placed in parallel with the discharge electrode through a minute gap, and the gap. A power supply for applying a voltage for forming an electric field in which an electron multiplication effect is generated between the discharge electrode and the counter electrode, and a moving or fixed object placed through a predetermined gap with respect to the counter electrode. Between the charged body and a grid electrode arranged in parallel with the counter electrode via a minute gap, and forming an electric field below the electric field generated by ozone in the space between the counter electrode and the body to be charged. An ozoneless non-contact charging device comprising a power supply for applying a voltage such that the surface potential of the body to be charged reaches a target value to the counter electrode and the grid electrode, respectively.