JP2003043806A - Electrostatic conveyance method for electrostatically charged toner and electrostatic conveyance device for electrostatically charged toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the stagnation of toners is resulted when even a piece of electrodes for electrostatic conveyance is disconnected. SOLUTION: The electrostatic conveyance method for the electrostatically charged toner of conveying the electrostatically charged image forming toners by an insulating substrate formed with electrode trains for electrostatic conveyance comprises disposing a common electrode in a position apart from the insulating substrate, impressing a voltage of the polarity reverse from the normal electrostatic charging polarity of the toners to this common electrode for a short time and instantaneously floating the toners stagnated at the disconnected electrode for electrostatic conveyance among the electrode trains of the electrostatic conveyance during the electrostatic conveyance of the toners toward the common electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of electrostatically carrying charged toner, in which charged image forming powder (herein, referred to as charged toner) is carried by an insulating substrate on which an electrostatic transfer electrode array is formed. The present invention relates to an electrostatic transport device for charged toner.

[0002]

2. Description of the Related Art A method of electrostatically carrying charged toner for image formation is to carry out macro-conveying of toner, in which a layer layer of toner is charged at a high voltage (1.5 to 2 KV).
There is a method to drive with. However, this method does not drive the toner continuously, but conveys the toner in a pulse shape by an electric field shock.

In Japanese Patent Laid-Open No. 59-181369, toner is transported by an electrostatic transport substrate having an electrostatic transport electrode group and a counter electrode substrate having a counter electrode to develop the electrostatic transport electrode group. There is described a developing device in which a potential that is half the maximum potential applied to the counter electrode is applied to the counter electrode.

In this developing device, the potential of the electrostatic transport electrode group becomes higher or lower than the potential of the counter electrode,
As a result, the toner is transported along the electrostatic transport substrate while going to and returning from the counter electrode substrate. In particular, the toner in the middle of each electrostatic transport electrode moves to the counter electrode.
For this reason, when the counter electrode is not present, the electric field is weak in the middle of each electrostatic transport electrode (there are no electric lines of force), so the toner deposited on each electrostatic transport electrode is lost, and the toner transport efficiency is reduced. Is improved.

In particular, since the toner in the vicinity of the center of each electrostatic carrying electrode moves to the counter electrode substrate, almost no accumulated toner exists, and the toner carrying efficiency can be improved.

[0006]

In the above developing device, if even one of the many electrostatic carrying electrodes is broken, the toner flow stops at the broken electrostatic carrying electrode in the entire width direction. , The toner has accumulated. The present invention provides a method for electrostatically conveying charged toner and a device for electrostatically conveying charged toner, which makes it possible to instantly float the toner staying on the broken electrostatic-conveying electrode and continue the uniform conveyance of the toner. To aim.

[0007]

In order to achieve the above object, the invention according to claim 1 electrostatically conveys charged toner for image formation by an insulating substrate on which an electrostatic conveyance electrode array is formed. In a method of electrostatically transporting charged toner, a common electrode is provided at a position distant from the insulating substrate, and a voltage having a polarity opposite to the regular charging polarity of the toner is applied to the common electrode for a short period of time to cause electrostatic discharge It is characterized in that the toner staying on the broken electrostatic carrying electrode of the electrostatic carrying electrode array during the carrying is instantaneously floated toward the common electrode.

According to a second aspect of the present invention, in the method of electrostatically transporting charged toner according to the first aspect, the magnitude and time of the voltage applied to the common electrode stay in the vicinity of the broken electrostatic transport electrode. Most of the toner is instantaneously separated from the insulating substrate, and most of the toner does not reach the common electrode.

According to a third aspect of the present invention, in the method of electrostatically transporting charged toner according to the first aspect, the surface of the common electrode is a thin insulating layer or a charge having a polarity opposite to the regular charging polarity of the toner is passed. It is characterized by being covered with an unforgivable semiconductor material.

According to a fourth aspect of the invention, in the method of electrostatically transporting charged toner according to the first aspect, the voltage is applied to the common electrode after the disconnection of the electrostatic transport electrode is detected. To do.

According to a fifth aspect of the present invention, in the method of electrostatically transporting charged toner according to the fourth aspect, when disconnection of the electrostatic transport electrode is first detected, the broken electrostatic transport electrode is sandwiched. The voltage is applied to the common electrode when an electrostatic field for accelerating the toner in the normal transport direction is formed between the normal electrostatic transport electrodes on both sides.

According to a sixth aspect of the present invention, in the method of electrostatically transporting charged toner according to the fourth aspect, when disconnection of a plurality of the electrostatic transport electrodes is detected, the largest number of disconnected electrostatic transport electrodes are used. The voltage is applied to the common electrode when an electrostatic field that accelerates the toner in the normal transport direction is formed between the normal electrodes for electrostatic transport on both sides surrounding the electrode for electrostatic transport by the electrodes. It is characterized by doing.

According to a seventh aspect of the present invention, there is provided a charged toner electrostatic transport device for electrostatically transporting charged image forming toner by an insulating substrate on which an electrostatic transport electrode array is formed. It has a common electrode provided at a distant position and a means for applying a voltage having a polarity opposite to the normal charging polarity of the toner to the common electrode for a short time, and the electrostatic charge is applied during electrostatic transport of the toner. The toner accumulated in the broken electrostatic transporting electrode of the transporting electrode array is momentarily floated toward the common electrode by applying the voltage to the common electrode.

According to an eighth aspect of the present invention, in the electrostatic transport device for charged toner according to the seventh aspect, the magnitude and time of the voltage applied to the common electrode stay in the vicinity of the broken electrostatic transport electrode. Most of the toner is instantaneously separated from the insulating substrate, and most of the toner does not reach the common electrode.

According to a ninth aspect of the present invention, in the electrostatic transport device for charged toner according to the seventh aspect, the surface of the common electrode is a thin insulating layer or a charge having a polarity opposite to the regular charging polarity of the toner is passed. It is covered with an unforgivable semiconductor material.

According to a tenth aspect of the present invention, in the electrostatic transport device for charged toner according to the seventh aspect, the voltage is applied to the common electrode after the disconnection of the electrostatic transport electrode is detected.

According to an eleventh aspect of the invention, in the electrostatic transport device for charged toner according to the tenth aspect, when the disconnection of the electrostatic transport electrode is first detected, the disconnected electrostatic transport electrode is sandwiched. The voltage is applied to the common electrode when an electrostatic field that accelerates the toner in the normal transport direction is formed between the normal electrostatic transport electrodes on both sides.

According to a twelfth aspect of the invention, in the electrostatic transport device for charged toner according to the tenth aspect, when disconnection of a plurality of the electrostatic transport electrodes is detected, the largest number of disconnected electrostatic transport electrodes are used. The voltage is applied to the common electrode when an electrostatic field that accelerates the toner in the normal transport direction is formed between the normal electrodes for electrostatic transport on both sides surrounding the electrode for electrostatic transport by the electrodes. To do.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION First, an example of an image forming apparatus to which the present invention is applied will be described. This image forming apparatus is a copying machine as shown in FIG. The drum-shaped photosensitive member 1 as an image carrier is rotationally driven in the clockwise direction by a driving unit (not shown). When a document is placed on the contact glass 2 and a print start switch (not shown) is pressed, the scanning optical system 5 including the document illumination light source 3 and the mirror 4 and the scanning optical system 8 including the mirrors 6 and 7 are moved. The original image is read. In this case, the document on the contact glass 2 is illuminated by the document illumination light source 3, and the reflected light thereof is transmitted through the mirrors 4, 6, 7 and the lens 9 to the image reading element 10.
Is received by and read.

The image signal from the image reading element 10 is
It is digitized by a circuit (not shown), is subjected to predetermined image processing, and is sent to the exposure means. As the exposing means, for example, a writing means having a laser optical system is used, and a laser diode (hereinafter referred to as an LD), which is a laser light source, is driven by the image signal after the image processing, and the laser light from the LD is reflected by the polygon mirror 13. After being reflected by, the photoconductor 1 is irradiated with the light through the mirror 14.

The photoconductor 1 is uniformly charged by the charging device 15 and is exposed by the laser beam to form an electrostatic latent image on the surface. The electrostatic latent image on the surface of the photoconductor 1 is developed by the developing device 16 and visualized as a toner image. On the other hand, a transfer paper 19 as a recording material is fed from a paper feed section 17A or 17B by a paper feed roller 18A or 18B, and the toner image on the photoconductor 1 is transferred to this transfer paper by a transfer charger 20 as a transfer means. It

The transfer paper 19 on which the toner image is transferred is
It is separated from the surface of the photoconductor 1 by a separation charger 21 as a separating means and is conveyed by a conveyor belt 22,
After the toner image is fixed by the fixing device 23, the toner image is discharged to the discharge tray 24 outside the machine. The toner remaining on the surface of the photoconductor 1 after the transfer is removed by the cleaning device 25, and the electric charge remaining on the surface of the photoconductor 1 is removed by the discharging lamp 2.
Erased by 6.

Next, the developing device 16 will be described in detail with reference to FIGS. As shown in FIG. 2, the developing device 16 has an electrostatic transport electrode array in which a plurality of electrostatic transport electrodes are arranged in the toner electrostatic transport direction, and transports the charged toner by electrostatic force. , An electrostatic transport substrate 31 which is an insulating substrate for pumping toner in the vicinity of the photoconductor 1 by electrostatic force, a toner box 32, and a flexible electrostatic transport substrate for feeding charged toner from the toner box 32 to the electrostatic transport substrate 31. 33, and a plurality of common electrodes arranged in the toner electrostatic transport direction.
Common electrode substrate 60 provided so as to face a part of
Then, a voltage having the same polarity as the normal charging polarity of the toner is applied to the common electrode of the common electrode substrate 60, and when any one of the plurality of electrostatic transfer electrodes is broken, the toner is normally transferred. The toner box 3 and a power source 62 for temporarily applying a voltage having a polarity opposite to the charging polarity (here, a positive voltage).
A charging roller 34 that charges the toner supplied to
The charging blade 35 that contacts the peripheral surface of the charging roller 34
A toner supply unit 36 for supplying toner to the toner box 32; a toner supply screw 37 for stirring the toner in the toner supply unit 36; and a toner detached from the electrostatic transport substrate 31 to be collected in the toner box 32. A first drive circuit as a drive unit that applies a drive waveform (about 5 to 100 V) for electrostatic toner transport and toner pumping to the toner recovery unit 38 for returning and the electrostatic transport electrodes of the electrostatic transport substrate 31. 41 and the 2nd drive circuit 42 grade.

D is provided between the photosensitive member 1 and the electrostatic transport substrate 31.
A DC bias (about 100 to 200 V), which is a developing bias voltage, is applied from the C power source 43. As shown in FIG. 3, the electrostatic transport substrate 31 includes a support substrate 51 having a width substantially equal to that of the photoconductor 1 in the axial direction of the photoconductor 1, and the support substrate 5.
1. A large number of electrostatic carrying electrodes 52 arranged in the direction of electrostatic carrying of toner on one surface, a thin insulating layer 53 covering the surface of the electrostatic carrying electrodes 52, and a surface of the insulating layer 53. And a surface coating layer 54.

As shown in FIG. 4, each electrostatic carrying electrode 52 extends parallel to the axial direction of the photoconductor 1 and has a predetermined interval in the toner electrostatic carrying direction orthogonal to the axial direction of the photoconductor 1. It is installed in. The surface coat layer 54 is provided to reduce contact with toner. As the supporting substrate 51, a substrate made of an insulating material such as a glass substrate, a resin substrate or a ceramic substrate, or a substrate made of a conductive material such as SUS and having an insulating film such as SiO ₂ formed thereon is used. it can. The electrostatic transfer electrode 52 is made of a conductive material such as Al or Ni—Cr on the support substrate 51.
A film having a thickness of 1 to 0.2 μm is formed, and this is patterned into an electrode shape using a semiconductor technique such as a photolithography technique.

The distance between the electrostatic transport electrodes 52 is preferably 2 to 10 times the toner diameter in order to secure a good toner transport speed and toner transport amount. Further, the width of the electrostatic carrying electrode 52 in the toner carrying direction is 1 to 3 of the toner diameter.
It is preferable that the number of times is twice in order to secure a good toner conveyance speed and a toner conveyance amount.

As the insulating layer 53, for example, SiO ₂ , S
iON, TiN, Ta ₂ O _{5 and the} like are formed to a thickness of 0.1 μm or less. By using a material having a large relative dielectric constant as the insulating layer 53, the electrostatic transport electrode 52
It is possible to lower the driving voltage of the toner, and the driving recoil and the conveyance speed of the toner are increased. The surface coat layer 54 is a film having a function of reducing the contact resistance between the toner transport surface and the charged toner interface, and is, for example, PTFE or P.
It is formed by coating a fluorine-based resin material such as FA to a thickness of 0.1 to 0.3 μm.

The flexible electrostatic transfer substrate 33 has the same basic structure as the electrostatic transfer substrate 31, but as shown in FIG. 5, a large number of insulating FPC boards 61 also function as a supporting board and an insulating layer. The electrodes 62a are arranged at predetermined intervals, and the FPC
The surface coat layer 64 is formed on the toner carrying surface side of the substrate 61.

The first drive circuit 41, as shown in FIG.
Electrostatic transfer electrodes 52, 52, 5 are arranged in sequence in the toner electrostatic transfer direction in the area 55 of the electrostatic transfer substrate 31 where toner is electrostatically transferred.
2 as one set, and three electrostatic transfer electrodes 52 each
A plurality of pulse drive voltages (driving waveforms) Va1, Vb1 and Vc1 of three phases (here, three phases) are applied to each. Similarly, the second drive circuit 42 includes three electrodes 5 arranged in sequence in the toner electrostatic transport direction in the area 56 where toner pumping is mainly performed on the electrostatic transport substrate 31.
2, 52, 52 are one set, and three electrodes 5 each
A plurality of pulse driving voltages (driving waveforms) Va2, Vb2, and Vc2 having a plurality of phases (three phases in this case) are applied to No. 2 respectively. The pulsed drive voltage by the first drive circuit 41 and the second drive circuit 42 may be, for example, 6-phase.

The first drive circuit 41 supplies pulsed drive voltages (drive waveforms) Va1, Vb1, Vc1 to the first drive frequency f1.
The second drive circuit 42 outputs the pulsed drive voltages (drive waveforms) Va2, Vb2, Vc2 at a second drive frequency f2 (f2> F1) at which the toner is pumped higher than the first drive frequency f1. To do. Specifically, the first drive frequency f1 is in the range of 1 KHz to 20 KHz, the second drive frequency f2 is in the range of 18 KHz to 45 KHz, the range of toner diameter to be used, the toner electrostatic transport speed to be obtained, and the degree of pumping. It is preferable to select according to the above.

The common electrode substrate 60, as shown in FIG.
It is provided so as to cover a region 55 of the electrostatic transport substrate 31 which mainly performs electrostatic transport of toner at a predetermined interval.
Although not shown, a supporting substrate similar to the electrostatic transport substrate 31,
A plurality of common electrodes arranged at regular intervals in the toner electrostatic transport direction are provided on the entire surface of the support substrate facing the electrostatic transport substrate 31.

Next, the electrostatic conveyance and pumping operation of toner by the developing device 16 will be described with reference to FIGS. First, as shown in FIG. 6, the first drive circuit 41 and the second drive circuit 42 have pulse-shaped drive waveforms Va1, Vb1, Vc1, and V that change between the ground G and the positive voltage +.
a2, Vb2, Vc2 (hereinafter referred to as Va, Vb, Vc)
Is output with the timing shifted. At this time,
As shown in FIG. 7, there is negatively charged toner T on the electrostatic transport substrate 31, and a plurality of continuous electrostatic transport electrodes 52 of the electrostatic transport substrate 31 are connected to the first drive circuit 41 from the first drive circuit 41 as shown in FIG. If “G (ground)”, “G”, “+ (positive voltage)”, “G”, and “G” are respectively applied, the negatively charged toner T is electrostatically conveyed to which “+” is applied. It is located on the electrode 52 for.

At the next timing, a plurality of electrostatic transfer electrodes 5 are formed.
2, as shown in FIG. 7, “+”, “G”,
"G", "+", and "G" are applied, and the toner T is negatively charged.
7, a repulsive force acts between the electrostatic transfer electrode 52 on the left side in FIG. 7 and the electrostatic transfer electrode 52 to which “+” is applied on the right side in FIG. Power acts. For this reason,
The toner T moves to the electrostatic transporting electrode 52 side to which “+” is applied. Further, at the next timing, as shown in FIG.
“+”, “G”, “G”, and “+” are applied to the toner T
Similarly, the repulsive force and the attraction force act between the left and right electrostatic transport electrodes 52, and the electrostatic transport electrodes 52 further move to the electrostatic transport electrode 52 side to which “+” is applied.

By thus changing the potential of the drive waveform applied to the electrostatic transport electrode 52 to apparently move the drive waveform, the toner T is applied to the electrostatic transport electrode 52 side to which "+" is applied. Since the toner T moves while being pulled by, the toner T is transported along the electrostatic toner transport surface of the electrostatic transport substrate 31. In the case of positively charged toner, the toner can be electrostatically conveyed by reversing the change pattern of the drive waveform.

As the drive frequency of the pulse-shaped drive waveform applied to the electrostatic transfer electrode 52 of the electrostatic transfer substrate 31 is increased, the moving speed of the toner (electrostatic transfer speed) is also increased, but the toner T is "+". When the electrostatic transfer electrode 52 changes to “G” when the electrostatic transfer electrode 52 moves to the electrostatic transfer electrode 52, the toner T is further transferred to the electrostatic transfer electrode 52. There is a pumping phenomenon that jumps when trying to move to.

According to experiments, the toner T is mainly transported within the range of 1 KHz to 20 KHz in the drive frequency of the pulse-shaped drive waveform applied to the electrostatic transport electrode 52 of the electrostatic transport substrate 31, and the toner T of the electrostatic transport substrate 31 is transported. The drive frequency of the pulse-shaped drive waveform applied to the electrostatic transport electrode 52 is 18 KHz to
In the range of 45 KHz, the toner T pumping phenomenon became large. In this case, the driving frequencies partially overlap because the occurrence of the pumping phenomenon is affected by the toner particle size, the driving voltage, and the like.

In the present copying machine, the area 55 where the toner is electrostatically transported from the first drive circuit 41 to the electrostatic transport substrate 31 is mainly used.
1K for the electrostatic transfer electrodes 52, 52, 52 ...
By applying pulsed driving voltages (driving waveforms) Va1, Vb1, and Vc1 having a first driving frequency f1 of Hz to 20 KHz, the toner T is moved along the toner electrostatic transport surface of the electrostatic transport substrate 31 by the photosensitive member 1. To the vicinity of.

18 KHz to 45 KH from the second drive circuit 42 to the electrostatic transfer electrodes 52, 52, 52, ... In a region 56 (developing portion) of the electrostatic transfer substrate 31 near the photosensitive member 1.
By applying the pulsed drive voltages (drive waveforms) Va2, Vb2, and Vc2 of the second drive frequency f2 of z respectively, the toner T is pumped in the vicinity of the photoconductor 1 as shown in FIG. Develop the electrostatic latent image on top.

Among the toners T to be pumped, there is the toner T that recoils in the normal electrostatic conveyance direction of the toner T, but as a whole, it is slowly conveyed in the normal toner electrostatic conveyance direction. According to an experiment, the toner being pumped exhibits a pumping phenomenon on the electrostatic transport substrate 31 by about 50 μm to 300 μm, but is further pumped by the DC bias between the photoconductor 1 and the electrostatic transport substrate 31. It has been confirmed that the toner being accelerated is accelerated and the pumping spreads to 500 μm to 1 mm. The common electrode substrate 60 is omitted in FIG.

During the electrostatic transport of toner, the electrostatic transport substrate 31
When any of the electrostatic carrying electrodes 52, 52, 52 ... In the area 55 for carrying toner electrostatically is disconnected, the power source 62 causes the common electrode of the common electrode substrate 60 to be charged with the regular toner. A voltage having the opposite polarity to the polarity is applied for a short time.
For this reason, the toner staying on the broken electrostatic-transporting electrode is instantly floated toward the common electrode, and the uniform toner electrostatic transport is continued.

The fact that the accumulated toner due to the broken electrostatic transporting electrode is momentarily floated in the direction of the common electrode to continue the uniform electrostatic transport of toner will be specifically described below based on experiments and examples of the present invention. . First, the experiment will be described. On the glass substrate, 300 electrostatic discharge electrode rows consisting of a NES electrode group having a width of 10 μm and a length of 50 mm are formed at an interval of 20 μm between the electrostatic transfer electrodes to prepare an electrostatic transfer substrate. 3 Nesa electrodes arranged in the transport direction
By connecting each book to the same power source, we connected them to three power sources. These three power supplies are referred to as power supplies A, B, and C. In a trial one-component developing device, a dry toner for electrophotography having an average particle size of 8.0 μm charged to an average charge amount of −15 μC / g was covered on one end of the glass substrate to cover a part of the electrode column for electrostatic transport. And the voltages of the power supplies A, B, and C every 100 μsec at a cycle of 300 μsec (+100 V,
+ 100V, 0V), (+ 100V, 0V, +100
V), (0 V, +100 V, +100 V), the toner moved from one end side to the other end side on the electrostatic transport substrate at a speed of 200 mm / sec.

When the moving state of the toner is photographed by a high speed camera and is reproduced in slow motion, the movement of the toner is studied.
It was confirmed that a part of the toner was scattered and floated up, though it was a little. The scattered / floating toner stains the inside of the copying machine or the printer and causes malfunction of the copying machine or the printer or stains on the image. Further, the scattered / floating toner may have an adverse effect on human health when discharged outside the copying machine or printer, and thus must be eliminated. Conventionally, the floating toner has been collected by various methods, but the best countermeasure against the floating toner is to prevent the floating toner from being originally generated.

Therefore, 0.05 to 0.
A glass plate was placed 1 mm apart. With this, it was possible to prevent the toner from scattering and floating, but after using it for a while, the glass plate placed away from the electrostatic transport substrate became black with toner, and the toner sometimes dropped onto the electrostatic transport substrate. Only that part of the toner could not be electrostatically conveyed, and a stripe-free portion was formed.

Therefore, instead of a simple glass plate, a glass plate having a Nesa electrode as a common electrode on one surface thereof is arranged with its electrode surface facing downward, that is, facing the electrostatic carrier substrate. It was confirmed that when scattered by 0.1 mm from the electrostatic transport substrate and -20 V to -50 V was applied to the common electrode, the amount of scattered floating toner was significantly reduced.

During this experiment, when the polarity of the voltage applied to the common electrode was accidentally reversed and was reversed, a large amount of toner jumped from the electrostatic transport substrate on which the electrostatic transport electrode array was formed and adhered to the common electrode. However, at the same time, it was found that the toner that had accumulated in the vicinity of the broken electrostatic-transporting electrode was substantially gone.

Originally, the electrostatic transfer electrodes should not be broken, but the width of the electrostatic transfer electrode array is 10 μm.
Since it is extremely narrow, the electrodes for electrostatic transport sometimes break. At that time, toner stayed near the broken electrostatic transport electrode, and finally, the toner flow was completely stopped near the broken electrostatic transport electrode.

Coincidentally, it was found that when a positive voltage having a polarity opposite to the normal charging polarity of the toner is applied to the common electrode, the toner staying near the broken electrostatic carrying electrode is reduced. The positive voltage, which is applied to the common electrode for a short time and has a polarity opposite to the normal charging polarity of the toner, is hereinafter referred to as "staying toner elimination pulse", or "elimination pulse" for short.
Experiments were carried out by varying (changing) the height, width, and application timing of this elimination pulse in Example 1 of the present invention.

The purpose of this experiment is to loosen and move the stagnant toner at the broken electrostatic carrying electrode without causing the toner to fly to the common electrode and adhere to the common electrode as much as possible. In Example 1 of the present invention, as in the above experiment, an electrostatic transfer electrode array composed of a NESA electrode group having a width of 10 μm and a length of 50 mm was formed on the glass substrate in the toner electrostatic transfer direction at an electrode interval of 20 μm for 300 times. An electrostatic transport substrate as an insulating substrate was formed by this formation, and the electrostatic transport electrodes were connected to three power sources by connecting the same power source to each of the three in the toner electrostatic transport direction. These three power supplies are referred to as power supplies A, B, and C. Using a trial one-component developing device, dry toner for electrophotography having an average particle size of 8.0 μm, which was charged to an average charge amount of −15 μC / g, was provided on one end of the electrostatic transport substrate with a part of an electrode column for electrostatic transport. The power supplies A, B, and C at intervals of 100 μsec at a cycle of 300 μsec (+100 V, +100 V, 0 V), (+
100V, 0V, + 100V), (0V, + 100V,
+ 100V) and toner is 200mm / sec
The electrostatic transfer substrate was moved from one end side to the other end side at the speed of.

A glass plate having a NESA electrode as a common electrode on one side thereof is placed 0.1% from the electrostatic transport substrate so that the electrode surface faces downward, that is, the electrostatic transport substrate faces.
mm apart, and -20V to -50V from the power source to the common electrode
V was applied to reduce the scattered airborne toner. Further, in the case where the electrostatic transport electrode is broken, a canceling pulse is applied from the power supply to the common electrode to loosen and move the accumulated toner on the broken electrostatic transport electrode.

In the first embodiment, a small amount of toner is placed on the electrostatic carrying electrode substrate having the broken electrostatic carrying electrode,
To the electrode for electrostatic transport which is normally electrostatically transporting the toner for about 1.2 msec while the electric power is applied to the common electrode 0.05 mm away from the electrostatic transport electrode substrate for about 1.2 msec. After the toner was retained, a cancellation pulse was applied to the common electrode from the power supply, and the voltage applied from the power supply to the common electrode was returned to -20V. During that time, the movement and flying state of the toner was photographed with a high-speed camera, and later, when the slow reproduction was performed and observed, the following was found.

As a matter of course, as the height of the elimination pulse is higher and the width of the elimination pulse is wider, less toner stays on the broken electrostatic transport electrode, but it jumps to the common electrode and adheres to the common electrode. There is also a lot of toner that does. The condition of the elimination pulse is that the pulse height of the elimination pulse is +80 V and the pulse width of the elimination pulse is 30 μsec, in which almost no toner adheres to the common electrode and almost no toner stays on the broken electrostatic transport electrode. Met.

Further, in the timing of the elimination pulse, when the potentials of the electrostatic carrying electrodes on both sides of the broken electrostatic carrying electrode are +100 V on one side and 0 V on the other side, the broken electrostatic discharge is generated. It was effective in eliminating the toner accumulated in the transport electrodes. In particular, in order to eliminate the staying toner on the broken electrostatic carrying electrode and carry the toner at the same time, the potential of the electrostatic carrying electrode in the toner electrostatic carrying direction is +100 V from the broken electrostatic carrying electrode. It was effective.

The electrostatic carrying electrode array is not only broken in places, but in rare cases, two adjacent electrostatic carrying electrodes are also broken, which is very unlikely. There is a possibility that the three matched electrostatic transport electrodes may be simultaneously broken.

Therefore, the same experiment was carried out by forcibly disconnecting the electrostatic carrying electrodes from two to three, and all of them were
The pulse height of the cancellation pulse is + 80V and the width of the cancellation pulse is 3
At 0 μsec, almost all the staying toner due to the broken electrostatic transport electrode was eliminated, and almost no toner adhered to the common electrode.

About experiment Video of high-speed camera (movie)
Therefore, the results of the simulation performed under the same conditions are shown in FIGS. 9 and 10. FIG. 9 shows the case where the elimination pulse is not applied to the common electrode in the first embodiment, and FIG. 10 shows the case where the elimination pulse is periodically applied to the common electrode in the first embodiment. Although the number of toner particles is larger in the actual experiment viewed with the high-speed camera, the basic toner movement is very similar to that shown in FIGS.

The images of 15 frames shown in FIGS. 9 and 10 respectively show changes in the toner position with time. From the upper left to the lower right of Figs. 9 and 10, 100 µs from the start
It shows the state of the experiment up to 1.4 msec every other ec. The band 71 on each frame in FIGS. 9 and 10 shows the electric potential in terms of concentration. The left side shows −600 V and the right side shows +60 V.
0 V is shown, and the middle of each represents the potential of the middle.

A white character 72 below the band 71 indicates the time and the average charge amount (q / m) of the toner. Twenty rectangles extending laterally below the white character 72 are the electrostatic transport electrodes 73, the width thereof is 10 μm, and the inter-electrode gap of the electrostatic transport electrodes 73 is 20 μm. The height of the electrostatic transporting electrode 73 is 5 μm, which is supposed to be a horizontally long rectangle, but it is vertically long because the horizontal direction is contracted. An empty portion in the middle of the location where the electrostatic transport electrodes 73 are arranged is the position where the three broken electrostatic transport electrodes are located.

Under the electrostatic transporting electrode 73, a black and white rectangle (original circle) 74 with a white background indicates the toner. The average particle diameter of the toner is 8.0 μm, and the average charge amount (q / m) of the toner is −15 μC / g. The white background is the space between the electrostatic transport substrate and the common electrode substrate 50 μm away from it, and the concentration indicates the potential. In the simulation, contrary to the actual situation, the electrostatic transport substrate having the electrostatic transport electrode array was placed above the common electrode substrate. Since the toner of this size has almost no influence of gravity, the electrostatic transport substrate and the common electrode substrate have the same vertical relationship.

In the whitish portion between the electrostatic transporting substrate and the common electrode substrate, the potential of the electrostatic transporting electrode is + 100V,
The darker portion indicates that the potential of the electrostatic carrying electrode is 0V. The strips 75 and 76 at the bottom of each frame in FIGS. 9 and 10 indicate a common electrode substrate, the strip 75 indicates an insulating layer, and the strip 76 indicates a common electrode. The height of the common electrode is 20 μm, and the thickness of the insulating layer thereon is 10 μm.

In the first (upper left) frame of FIG. 9, the toner is uniformly distributed on the electrostatic transporting substrate, but 100 μs.
For each ec, the voltage applied to each electrostatic transport electrode is +1
Each time it changes to 00V and 0V, it gradually moves from left to right. And the toner that hits the right wall is programmed to come out of the left wall.

As seen from the movements of the individual toners in FIG. 9, it can be seen that the eight toners in the middle portion where the electrostatic carrying electrode does not exist do not move at all. As a result, as time passes, the toner stays on the left,
At the last frame (bottom right) after 1.4 msec, the toner is piled up to form a small tower. At this time, in the right half, most of the toner that was there moved to the right, passed through the right wall, and went to the left half, so there is only a small amount of toner remaining.

In the actual case, the toner on the right side of the broken electrostatic carrying electrode moves rightward to the end of the electrostatic carrying substrate, and the toner on the left side of the broken electrostatic carrying electrode breaks. However, the toner on the right side of the broken electrostatic transport electrode runs out of toner, and the toner aggregates on the left side of the broken electrostatic transport electrode. Is exactly the same as the simulation.

Next, in Example 1, 0.6 msec
Each time, a simulation was performed by applying a cancellation pulse voltage of +80 V and 30 μsec to the common electrode. The result is shown in FIG. In FIG. 10, the seventh and thirteenth frames are whitish because +80 V is applied to the common electrode. After that, looking at the 8th frame and the 14th frame, it can be seen that the toner in the middle portion where the electrostatic carrying electrode does not exist (the electrostatic carrying electrode is broken) is gone. That is, this is the effect of the cancellation pulse.

Due to the elimination pulse, the toner in the middle portion where there was no electrostatic transporting electrode that did not move until then moved because the electrostatic transporting electrodes on both sides of the toner moved + 100V and 0V, respectively. , Horizontally, 1.0e ⁺⁶
Only an electric field of [V / m] is applied, there is almost no electric field that pulls the toner vertically and downward, and the adhesive force (van der Waals force and liquid bridge force) that acts between the toner and the electrostatic transport substrate. However, when +80 V was applied to the common electrode, a strong vertical electric field (up to about 1.3 V) was applied between the common electrode and the electrostatic transport electrode at 0 V.
e ⁺⁶ [V / m]), and a strong vertical downward electrostatic force acts on the negatively charged toner to cut off the adhesion of the toner to the electrostatic transport substrate.

Various examinations were made on the application timing of the elimination pulse. At least when one of the electrostatic carrying electrodes on both sides of the broken electrostatic carrying electrode was at 0 V, the broken electrostatic carrying electrode was used. The reason why it was good to loosen and move the stagnant toner is considered to be due to the strong vertical electric field.

Further, when a cancel pulse is applied from the power supply to the common electrode, a disconnection detecting means for detecting disconnection of any one of the electrostatic transfer electrodes of the electrostatic transfer electrode array is provided, and this disconnection detection is performed. According to the detection signal from the means, after one of the electrostatic carrying electrodes of the electrostatic carrying electrode array is broken,
If the cancellation pulse is applied from the power supply to the common electrode, unnecessary power consumption can be prevented. .

Further, when the disconnection detecting means first detects the disconnection of the electrostatic carrying electrode, the toner is transported in the normal carrying direction between the normal electrostatic carrying electrodes sandwiching the broken electrostatic carrying electrode. By applying the elimination pulse from the power source to the common electrode when the electrostatic field that accelerates to the point is formed, it is possible to efficiently eliminate the staying toner due to the broken electrostatic transport electrode.

Further, when the disconnection detection means detects disconnection of a plurality of electrostatic transfer electrodes, the largest number of disconnected electrostatic transfer electrodes among the disconnected electrostatic transfer electrodes at each location,
A cancel pulse is applied from the power supply to the common electrode when an electrostatic field that accelerates the toner in the normal transport direction is formed between the normal electrostatic transport electrodes that surround the electrostatic transport electrodes. By doing so, it is possible to efficiently eliminate the staying toner due to the broken electrostatic transport electrode.

As described above, according to the first embodiment, the common electrode is provided at a position distant from the electrostatic carrying substrate as the insulating substrate, and a voltage having a polarity opposite to the regular charging polarity of the toner is shorted to the common electrode. When the toner is electrostatically transferred for a period of time, the toner staying on the broken electrostatic transfer electrode of the electrostatic transfer electrode array is momentarily floated toward the common electrode, so that the electrostatic transfer electrode is disconnected. It is possible to continue uniform toner electrostatic transport.

Further, according to the first embodiment, the magnitude and time of the elimination pulse applied to the common electrode are such that most of the toner staying in the vicinity of the broken electrostatic transport electrode is instantaneously separated from the electrostatic transport substrate, and Since most of the area does not reach the common electrode, it is possible to eliminate the staying toner due to the broken electrostatic carrying electrode, and at the same time, to minimize the toner attached to the common electrode.

Further, according to the first embodiment, unnecessary power consumption can be prevented by applying the elimination pulse to the common electrode after detecting the disconnection of the electrostatic carrying electrode. Further, according to the first embodiment, when the disconnection of the electrostatic transport electrode is first detected, the toner is transported in the normal transport direction between the normal electrostatic transport electrodes on both sides of the disconnected electrostatic transport electrode. By applying the elimination pulse to the common electrode when the electrostatic field that accelerates to the background is formed, it is possible to efficiently eliminate the staying toner due to the broken electrostatic transport electrode.

Further, according to the first embodiment, when disconnection of a plurality of electrostatic transport electrodes is detected, the largest number of disconnected electrostatic transport electrodes are used for normal operation on both sides surrounding the electrostatic transport electrodes. By applying a cancellation pulse to the common electrode when an electrostatic field that accelerates the toner in the normal transport direction is formed between the electrostatic transport electrodes, the broken toner due to the broken electrostatic transport electrodes is efficiently removed. It can be resolved.

Next, a second embodiment of the present invention will be described. In the first embodiment, the condition is set such that the toner flying to the common electrode does not come out as much as possible, but still, a small amount of toner flies to the common electrode and adheres to the common electrode, or once again adheres to the common electrode, the electrostatic discharge occurs again. It was observed in the image of the high-speed camera that it returned to the transfer board.

Then, a small amount of toner was generated which moved in the opposite direction and collected at the left end of the electrostatic transport substrate. When this toner was collected and its charge amount was measured, it was +3.5 μC /
It was found to be g. These toners fly to the common electrode when the elimination pulse (+ 80V) is applied to the common electrode, where positive charges are injected to reverse the charging polarity from the original negative polarity to the positive polarity and return to the electrostatic carrier substrate. Therefore, it is considered that the toner has moved from right to left, contrary to the negatively charged toner. Therefore, in Example 2, when an insulating layer made of a SiO ₂ layer having a thickness of about 0.1 μm was formed on the surface of the common electrode in Example 1, the generation of reverse polarity toner due to charge injection almost disappeared. . The same effect can be obtained by covering the surface of the common electrode with, instead of the insulating layer, a semiconductor material that does not allow passage of charges having a polarity opposite to the regular charging polarity of the toner.

As described above, according to the second embodiment, since the surface of the common electrode is covered with the thin insulating layer or the semiconductor material which does not allow the passage of the charge having the opposite polarity to the regular charge polarity of the toner, the common electrode is formed. It is possible to prevent excessive charge injection from the toner to the toner.

Next, a third embodiment of the present invention will be described. According to the second embodiment, there is no toner that returns to the electrostatic transport substrate by reversing the charging polarity, but instead, the amount of toner that continues to adhere to the common electrode increases. If the amount is small, there is no problem, but if the amount is large, there is a high possibility that the shape and strength of the electric field are adversely affected. Therefore, in the third embodiment, the second embodiment
In place of the SiO ₂ layer, non-adhesive silicon resin was spray-coated to a thickness of about 10 μm on the surface of the common electrode. As a result, in addition to the generation of the opposite polarity toner, the problem that the toner adheres to the common electrode for a long period of time is also solved.

[0077]

As described above, according to the first aspect of the invention, it is possible to continue uniform toner electrostatic conveyance even if the electrostatic conveyance electrode is broken. According to the second aspect of the present invention, it is possible to eliminate the staying toner due to the broken electrostatic transport electrode, and at the same time, to minimize the amount of toner attached to the common electrode.

According to the third aspect of the present invention, it is possible to prevent extra charge injection from the common electrode into the toner.
According to the invention of claim 4, unnecessary power consumption can be prevented. According to the invention of claim 5, efficiently,
It is possible to eliminate the staying toner due to the broken electrostatic transport electrode.

According to the invention of claim 6, efficiently,
It is possible to eliminate the staying toner due to the broken electrostatic transport electrode. According to the invention of claim 7, it is possible to continue uniform toner electrostatic transport even if the electrostatic transport electrode is broken. According to the invention of claim 8, the staying toner due to the broken electrostatic transport electrode can be eliminated, and at the same time, the toner attached to the common electrode can be minimized.

According to the invention of claim 9, extra charge injection from the common electrode to the toner can be prevented.
According to the invention of claim 10, unnecessary power consumption can be prevented. According to the eleventh aspect of the present invention, it is possible to efficiently eliminate the staying toner due to the broken electrostatic transport electrode. According to the twelfth aspect of the invention, it is possible to efficiently eliminate the staying toner due to the broken electrostatic transport electrode.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an image forming apparatus to which the present invention is applied.

FIG. 2 is a sectional view showing a developing device of the image forming apparatus.

FIG. 3 is a cross-sectional view showing a carrier substrate in the developing device.

FIG. 4 is a plan view showing the carrier substrate.

FIG. 5 is a schematic view showing a part of the image forming apparatus.

FIG. 6 is a waveform diagram showing a drive waveform of an electrode for electrostatic transport on the transport substrate.

FIG. 7 is a diagram for explaining the principle of electrostatic toner transport in the developing device.

FIG. 8 is a diagram for explaining electrostatic toner transport and pumping of the developing device.

FIG. 9 is a diagram showing a simulation result of a temporal change of the toner position when the elimination pulse is not applied to the common electrode in the electrostatic toner transport device.

FIG. 10 is a diagram showing a simulation result of a temporal change of the toner position when a cancel pulse is applied to the common electrode in the electrostatic toner transport device.

[Explanation of symbols]

1 photoconductor 31 Electrostatic transfer board 41 first drive circuit 42 Second drive circuit 52 Electrostatic transfer electrode 60 common electrode substrate 62 power

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H077 AB02 AB14 AB15 AC01 AC13                       AC16 AD07 AD13 AD14 AD23                       AD35 AE02 AE03 DA24 DA42                       DA57 DB25 EA14 EA16 GA03                       GA04

Claims (12)

[Claims] 1. A method of electrostatically transporting charged toner for electrostatically transporting charged toner for image formation by an insulating substrate on which an electrostatic transport electrode array is formed, wherein a common electrode is provided at a position distant from the insulating substrate. A voltage having a polarity opposite to the regular charging polarity of the toner is applied to the common electrode for a short time, and electrostatic discharge of the electrostatic discharge electrode array in the electrostatic transfer electrode array during electrostatic transfer of the toner is performed. A method of electrostatically transporting charged toner, characterized in that the toner staying on the electrodes is momentarily floated toward the common electrode. 2. A method of electrostatically transporting charged toner according to claim 1, wherein the magnitude and time of the voltage applied to the common electrode is such that most of the toner stayed near the broken electrostatic transport electrode. A method of electrostatically transporting charged toner, characterized in that the charged toner is instantaneously separated from the insulating substrate and most of the area does not reach the common electrode. 3. The method of electrostatically transporting charged toner according to claim 1, wherein the surface of the common electrode is covered with a thin insulating layer or a semiconductor material that does not allow passage of charges having a polarity opposite to the regular charging polarity of the toner. A method of electrostatically transporting charged toner, which is characterized in that 4. The electrostatic charging method for charged toner according to claim 1, wherein the voltage is applied to the common electrode after the disconnection of the electrostatic transfer electrode is detected. Transport method. 5. The method for electrostatically transporting charged toner according to claim 4, wherein when a disconnection of the electrostatic transport electrode is first detected, the static charge on both sides of the broken electrostatic transport electrode is normal. A method of electrostatically transporting charged toner, comprising applying the voltage to the common electrode when an electrostatic field that accelerates the toner in a regular transport direction is formed between the electrodes for electrical transport. 6. A method of electrostatically transporting charged toner according to claim 4, wherein, when disconnection of a plurality of said electrostatic transport electrodes is detected, said electrostatic discharge is carried out by the largest number of said electrostatic transport electrodes. The voltage is applied to the common electrode when an electrostatic field for accelerating the toner in the normal transport direction is formed between the normal electrostatic transport electrodes on both sides surrounding the transport electrode. Electrostatic transport method for charged toner. 7. A charged toner electrostatic transport device for electrostatically transporting charged image forming toner by an insulating substrate on which an electrostatic transport electrode array is formed, the electrostatic toner transporting device being provided at a position apart from the insulating substrate. And a means for applying a voltage having a polarity opposite to the regular charging polarity of the toner to the common electrode for a short time. The electrostatic transport device for charged toner, wherein the toner staying on the broken electrostatic transport electrode is instantly floated toward the common electrode by applying the voltage to the common electrode. 8. The electrostatic carrying device for charged toner according to claim 7, wherein the magnitude and time of the voltage applied to the common electrode is such that most of the toner staying in the vicinity of the broken electrostatic carrying electrode. An electrostatic transport device for charged toner, characterized in that it is separated from the insulating substrate instantaneously and most of it is in a range where it does not reach the common electrode. 9. The electrostatic transport device for charged toner according to claim 7, wherein the surface of the common electrode is covered with a thin insulating layer or a semiconductor material that does not permit passage of charges having a polarity opposite to the regular charging polarity of the toner. An electrostatic transport device for charged toner, which is characterized in that 10. The electrostatic charging device for charged toner according to claim 7, wherein the voltage is applied to the common electrode after the disconnection of the electrode for electrostatic transfer is detected. Transport device. 11. The electrostatic transport device for charged toner according to claim 10, wherein when a disconnection of the electrostatic transport electrode is first detected, the static charge on both sides of the electrostatic transport electrode which is disconnected is normal. An electrostatic transport device for charged toner, wherein the voltage is applied to the common electrode when an electrostatic field that accelerates the toner in a normal transport direction is formed between the electrodes for electrical transport. 12. An electrostatic carrying device for charged toner according to claim 10, wherein, when disconnection of a plurality of said electrostatic carrying electrodes is detected, said electrostatic carrying is performed by the largest number of said broken electrostatic carrying electrodes. The voltage is applied to the common electrode when an electrostatic field for accelerating the toner in the normal transport direction is formed between the normal electrostatic transport electrodes on both sides surrounding the transport electrode. Electrostatic transport device for charged toner.