JPH11174789A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate toner attached to a control electrode and to realize a stable printing action by applying such a voltage that an electric field is formed in a direction that the toner is separated from the control electrode in shorter time than a non-printing term synchronously with the start of a non-printing cycle in the midst of the printing action executed based on a clock pulse. SOLUTION: A printing part 1 is constituted of a flying control part 2 opposed to the outside circumferential surface of a toner carrier 31 and a counter electrode 11. By applying the voltage on the ring-like control electrode in response to an image signal, the passing state of the toner T passed through a gate in the direction of the electrode 11 from the carrier 31 is selectively controlled. Then, the voltage whose polarity is reverse to the toner T is applied on the carrier 11 synchronously with the start of the non-printing cycle of the printing color pulse. Thus, the toner T made to collide with an electrode substrate and attached to it as it is separated from the electrode substrate and made to fly in the direction of the carrier 31. Then, the reverse-polarity voltage is applied in the shorter term than the non-printing term.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a printing section of a digital copying machine and a facsimile apparatus, a digital printer, a plotter, and the like, and by causing a developer such as a toner to fly on a recording medium such as paper. The present invention relates to an image forming apparatus for forming an image.

[0002]

2. Description of the Related Art As an image forming apparatus for outputting an image signal as a visible image on a recording medium such as paper, a developer such as charged toner particles (hereinafter referred to as toner) is used in accordance with the image signal. A method of selectively controlling flight has been proposed.

[0003] In this type of system, since the selective flight control of the toner according to the image signal is constituted by a control electrode having a fine opening, if the supply of the toner is not performed uniformly, the recording is performed. The image tends to be uneven on the medium, and high-speed recording is difficult.

Further, since the toner is liable to cause clogging in the vicinity of the control electrode, there is a need for a toner characteristic before flying which is easy to fly and has no lump, and a flying control method which is free from adhesion to the control electrode and clogging. Was.

Therefore, by providing a control electrode having two layers and applying a voltage that generates an electric field that attracts toner to the electrode of the two layers of control electrodes closer to the toner carrier at the time of printing, sufficient toner is provided. The flight amount was obtained.

However, at this time, if a voltage that attracts toner to all the electrodes is applied, a problem occurs in that the electrodes are stained and clogged. Therefore, printing is performed to remove the adhered toner. There has been proposed an image forming apparatus that generates an electric field in which the attached toner returns when the dot data is not sent.

For example, Japanese Patent Application Laid-Open No. Sho 58-44457 proposes a method in which an alternating electric field is applied between a developer support and control means to promote the flying of the developer.

That is, by applying an AC voltage between a toner conveying member and a control member such as an aperture board (in which two electrodes are provided via an insulating layer and a row of holes are formed in the two electrodes), the toner is applied. This reduces the adhesion of the toner to the conveying member on the conveying member, enables recording with a low applied voltage, and cleans the toner conveying member side of the control unit when the toner reciprocates between the control units. Therefore, an image recording method and apparatus capable of obtaining a stable image for a long period of time have been proposed.

In JP-A-58-96570, an alternating electric field is applied between a developer support and a control member, and a voltage having a polarity opposite to that of the developer is applied to the developer support during non-printing. A method of returning the developer of the control member to the developer carrier has been proposed.

That is, when there is no input signal for forming an image, a DC voltage of the opposite polarity to the toner is superimposed on the AC component of the toner with respect to the conveying member, or a DC voltage of the opposite polarity to the toner is applied. In addition to eliminating the clogging of the opening due to and eliminating the accumulation of toner on the reference electrode, unnecessary toner scattering can be reduced, and image stains can be further reduced. An image recording device capable of forming an image has been proposed.

Further, Japanese Patent Application Laid-Open No. 4-344263 discloses a configuration in which the control electrode of the upper and lower layers cooperates to control the passage of the developer through the control electrode. There is disclosed a method of generating an electric field such that the developer is attracted to the control electrode during printing, and generating an electric field such that the developer is attracted to the developer carrier during non-printing.

That is, at the timing when the print dot data is sent in the print clock, an electric field is generated between the developer supply roller and the upper electrode such that the developer is sucked from the developer supply roller side to the upper electrode side, and printing is performed. At the timing when the print dot data in the clock is not sent, an electric field is generated between the developer supply roller and the upper electrode so that the developer is sucked from the upper electrode side to the developer supply roller side, so that the developer passage hole is formed. An image forming apparatus has been proposed in which the developer is sufficiently supplied to the developer passage and the developer passage hole is not clogged with the developer.

Further, Japanese Patent Application Nos. Hei 8-33666 and Hei 8 are disclosed.
In Japanese Patent Application No. 4-48851 and Japanese Patent Application No. 8-57259, the control electrode selectively applies two or more potential states during non-printing, and returns toner adhering to the electrode to the toner carrier during non-printing. We have proposed an image forming apparatus that performs cleaning.

That is, in the above three materials, the electric field that does not allow the toner to pass from the control electrode to the toner carrier is applied to the control electrode during the non-printing operation, instead of applying a potential that does not simply pass through the control electrode. In order to operate, in an image forming apparatus that removes toner on an electrode by applying a voltage to the control electrode, or in a so-called matrix control composed of two layers of a matrix, a non-contact of an electrode adjacent to the electrode to be controlled An image forming apparatus that efficiently removes toner adhered to a control electrode by optimizing a printing voltage without affecting printing is disclosed.

[0015]

As described above, in an image forming apparatus typified by the prior art, the toner on the toner carrier is transferred to the gate portion having an opening through which the toner can pass by the image signal. A method of controlling the passage of toner by applying a corresponding electric field has been adopted. However, in such an image forming apparatus, a gap between a toner carrier and a gate portion including a control electrode is narrow, and Since the flight path of the gate for controlling the passage of the toner is also narrow, it has been difficult to completely prevent the toner from adhering to the gate including the control electrode.

Further, the toner adheres not only to the opening through which the toner passes but also to the surface of the control electrode facing the toner carrier, and this adhesion of the toner causes various problems.

For example, when the toner adheres to the wall surface of the opening through which the toner passes, the passage through which the toner passes is usually only about several tens of times the particle diameter of the toner. The flight passage is blocked.

Furthermore, even when the toner adheres to the toner carrier side of the gate portion, the influence of the electric charge of the attached toner affects the toner flight amount passing through the toner flight path and the toner passage of the gate portion.

Therefore, the above-mentioned prior art (Japanese Patent Laid-Open No. 58-44)
457, JP-A-58-96570, JP-A-4-3442
63) In the non-printing period, an electric field opposite to the electric field applied to the electrode on the toner carrier side of the two-layer control electrode during the printing period, that is, a toner flying electric field toward the toner carrier is applied. Thus, it has been proposed to suppress the toner adhesion at the gate portion, which is useful in that the flight control without adhesion to the control electrode portion and clogging can be performed.

However, when two layers of electrodes are required and the above-described reverse electric field is formed in a non-printing period, the flying property in the next printing period is significantly impaired.

That is, when a printing voltage is applied to the control electrode, a flying electric field is applied to the toner on the toner carrier in the direction of the control electrode or the counter electrode, and the toner on the toner carrier gradually stops from a stopped state. Although the toner accelerates and passes through the gate, even if the formation of the flying electric field is stopped before passing through the gate, the toner continues to fly due to kinetic energy. Therefore, even if an electric field in the opposite direction is formed immediately after the end of printing, most of the toner flying toward the control electrode or the counter electrode continues to fly and forms a toner image on the recording material.

On the other hand, the toner adhering to the gate portion separates from the gate and moves toward the toner carrier while accelerating. Even if the electric field directed to the toner carrier is immediately switched to the printing electric field, the toner remains in the toner carrier direction. Kinetic energy which flies toward the counter electrode, and does not immediately fly in the direction of the counter electrode, which causes a problem that the flying amount is reduced.

Also, Japanese Patent Application Nos. Hei 8-33666 and Hei 8
In the technical contents described in JP-A-48851 and Japanese Patent Application No. 8-57259, the main configuration is that the control electrode selectively applies two or more potential states at the time of non-printing. The remaining toner can be returned to the toner carrier, and the electrode can be cleaned.

That is, in order to apply an electric field such that the toner travels from the control electrode to the toner carrier, instead of giving the control electrode a potential that does not simply pass through the control electrode electrode during non-printing, the control voltage is applied to the control voltage. And a method for removing toner on the electrodes by applying a non-printing voltage to the electrode adjacent to the electrode to be controlled in the case of a so-called matrix control composed of two layers of a matrix. Therefore, the present invention is useful in that it discloses an image forming apparatus capable of efficiently removing toner attached to a control electrode without affecting printing.

However, when print data is always sent in response to a clock pulse as in the case of single drive or matrix column electrode drive, it is impossible to selectively apply voltage to adjacent electrodes. Since the printing voltage is applied to the row electrodes of the matrix by scanning in order,
Selective voltage application becomes possible to each row electrode).

The present invention has been made in view of the above problems, and determines a printing period and a non-printing period in a printing operation based on a clock pulse, and synchronizes with the start of the non-printing period to make the printing period longer than the non-printing period. By applying a voltage to form an electric field in a direction to separate the toner from the control electrode for a short time,
It is an object of the present invention to provide an image forming apparatus capable of removing toner adhering to an electrode and realizing stable printing.

In addition, in addition to the above, the present invention further comprises a point to which a voltage for removing toner is applied to the toner carrier, the control electrode,
An object of the present invention is to provide an image forming apparatus which can apply a voltage to a conductive layer provided on a toner carrier side of a control electrode and can employ a method most suitable for the structure of the apparatus.

[0028]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a developer carrier for carrying a developer charged to a predetermined polarity; and a predetermined gap between the developer carrier and the developer carrier. A plurality of gate means arranged so as to allow the developer on the developer carrier to pass therethrough; a control electrode arranged to surround the gate means and capable of applying a predetermined voltage; A counter electrode which is disposed opposite to the image agent carrier and is capable of applying a predetermined voltage; and the control means and the counter electrode are exposed from the gate means to the control electrode and the counter electrode based on a print cycle and a non-print cycle of a print clock pulse. A voltage applying means for selectively applying a voltage for providing a state in which the image material passes or does not pass therethrough, the developer carrying device for applying a predetermined voltage to the developer carrier; Body voltage applying means, and a non-marking of the print clock pulse. Control means for applying a voltage having a polarity opposite to the charging polarity of the developer for a period shorter than the non-printing period to the developer carrier from the developer carrier voltage applying means in synchronization with the start of the cycle. It is characterized by having.

According to a second aspect of the present invention, there is provided the image forming apparatus according to the first aspect.
In the above, tB <tW and 1 / 2tB <, where tC is the time for applying an applied voltage having a polarity opposite to the charging polarity of the developer to the developer carrier, tB is the printing time, and tW is the non-printing time.
It is characterized in that tC <tW.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the applied voltage having a polarity opposite to that of the developer applied to the developer carrier is applied to the control electrode at the time of printing. And a voltage higher than the voltage applied to the control electrode during non-printing.

According to a fourth aspect of the present invention, in the third aspect, the voltage applied to the developer carrier during non-printing is substantially the same as the voltage applied to the control electrode during the non-printing period. It is characterized by being.

According to a fifth aspect of the present invention, there is provided an image forming apparatus, comprising: a developer carrier for carrying a developer charged to a predetermined polarity; and a developer provided at a predetermined gap from the developer carrier. A plurality of gate means through which the developer on the carrier can pass, a control electrode arranged to surround the gate means and capable of applying a predetermined voltage, and a developer carrier of the control electrode A counter electrode disposed opposite to the opposite side and capable of applying a predetermined voltage; and a developer passing or passing from the gate means to the control electrode and the counter electrode based on a print cycle and a non-print cycle of a print clock pulse. An image forming apparatus having a voltage applying means capable of selectively applying a voltage for giving a state in which the developing agent is not provided, further comprising a developer carrier voltage applying means for applying a predetermined voltage to the developer carrier. , Synchronized with the start of the non-printing cycle of the print clock pulse Te, characterized by comprising a control means for applying a first non-printing voltages of developer having the same polarity, the second non-printing voltage absolute value than the first non-printing voltage is small.

[0033] The image forming apparatus according to the sixth aspect is the fifth aspect.
, The application time during printing applied to the control electrode is t
B, the application time during non-printing is tW, and the first non-printing time is t
When C1 and the second non-printing time are tC2, tB <t
W and tW = tC1 + tC2.

According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, the application time during printing applied to the control electrode is tB, the first non-printing time is tC1, and the second non-printing time is tC2. Where と す る tB <tC1 and ｔ tB
<TC2.

According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the second non-printing voltage has substantially the same voltage value as the voltage applied to the developer carrier.

According to a ninth aspect of the present invention, there is provided an image forming apparatus, comprising: a developer carrier for supporting a developer charged to a predetermined polarity; and a developer and a developer having a predetermined gap therebetween. A plurality of gate means through which the developer on the carrier can pass, a control electrode arranged to surround the gate means and capable of applying a predetermined voltage, and a developer carrier of the control electrode A counter electrode disposed opposite to the opposite side and capable of applying a predetermined voltage; and a developer passing or passing from the gate means to the control electrode and the counter electrode based on a print cycle and a non-print cycle of a print clock pulse. An image forming apparatus provided with voltage applying means capable of selectively applying a voltage for giving a state in which the developing agent does not come into contact with the developing agent carrier on the developer carrier side via the control electrode and an insulating material. A conductive layer is provided, and a non-printing clock pulse is applied to the conductive layer. In synchronization with the shaped cycle start, the voltage of the developer having the same polarity, characterized by comprising a control means for applying a short period of time than non-printing period.

According to a tenth aspect of the present invention, in the ninth aspect, the voltage application time of the same polarity as the developer to the conductive layer provided on the developer carrier side of the control electrode is tS, and the printing time is When tB and the non-printing time are tW, 1/2 tB <
It is characterized in that tS <tW and tB <tW.

In the image forming apparatus according to the present invention, the absolute value of the applied voltage having the same polarity as that of the developer during non-printing applied to the conductive layer is applied to the control electrode during printing. It is characterized by being smaller than the absolute value of the voltage and larger than the absolute value of the voltage applied to the control electrode during non-printing.

According to a twelfth aspect of the present invention, in the image forming apparatus according to the eleventh aspect, the voltage applied to the conductive layer provided on the developer carrier side of the control electrode when printing is performed during the non-printing period to the control electrode. It is characterized in that the value is substantially the same as the applied voltage.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a cross section of a printer having an image forming apparatus according to the present embodiment mounted thereon, and an outline of each element will be described with reference to FIGS.

In the following description, an image forming apparatus having a configuration corresponding to a negatively charged toner will be described in detail. However, when a positively charged toner is used, each of the applied voltages is appropriately adjusted accordingly. What is necessary is just to set a polarity.

As shown in FIG. 2, the image forming apparatus according to the present method forms a toner image on the recording material P by controlling the toner in the toner supply unit 3 in accordance with an image signal by the flight control unit 2. .

A paper feed unit 4 is provided on the upstream side in the conveying direction of the recording material P to the printing unit 1. The paper supply unit 4 includes a recording material P
And a recording material storage unit 40 for storing
And a pair of registration rollers 42 for transporting the supplied recording material P at the timing of printing.
It is guided to the printing unit 1 by 3 and the paper pressing plate 44.

The paper supply unit 4 includes a paper supply sensor (not shown) for detecting that the recording material P has been supplied.
The pickup roller 41 and the registration roller 42 are rotationally driven by a driving device (not shown) according to a driving signal from the controller unit 7.

On the downstream side in the transport direction of the recording material P from the printing unit 1, the toner image formed on the recording material P in the printing unit 1 is heated and pressed to fix the toner image on the recording material P. A part 6 is provided. The fixing unit 6 includes a heater 6
1 includes a heat roller 62, a pressure roller 63, and a temperature sensor 64.

The heat roller 62 is made of, for example, an aluminum tube having a thickness of 2 mm. The heater 61 is formed of, for example, a halogen lamp, and is included in the heat roller 62.
The pressure roller 63 is made of, for example, a silicone resin.

The heat roller 62 and the pressure roller 63 provided opposite to each other are pressurized by a spring or the like (not shown) at both ends of each shaft so that the recording material P can be pressed therebetween. Has been added. The temperature sensor 64 measures the temperature of the surface of the heat roller 62.

The measured value is controlled by a temperature control unit (not shown) of the controller unit 7, and the temperature of the heater 61 is changed according to the surface temperature of the heat roller 62 based on the measurement result of the temperature sensor 64.
By controlling N / OFF and the like, the surface temperature of the heat roller 62 is maintained at, for example, 150 ° C.

The fixing section 6 has a paper discharge sensor (not shown) for detecting that the recording material P has been discharged.
The materials of the heater 61, the heat roller 62, the pressure roller 63, and the like are not particularly limited. Further, the temperature of the surface of the heat roller 62 is not particularly limited.
Furthermore, the fixing unit 6 may be configured to fix the toner image by heating or pressing the recording material P.

Although not shown, on the discharge side of the recording material P from the fixing unit 6, a discharge roller for discharging the recording material P processed by the fixing unit 6 to the outside of the apparatus, and a discharged recording material P A receiving tray is provided.

Further, the heat roller 62 and the pressure roller 6
3, and the discharge roller are rotationally driven by a driving device (not shown).

The toner supply unit 3 agitates the toner T in the toner storage tank 35 containing the toner T to prevent the toner T in the toner storage tank 35 from shifting.
Cylindrical carrier (sleeve) that carries and transports toner T
A toner carrier 31, a supply roller 33 for supplying the toner to the toner carrier 31, a doctor that applies a predetermined charge to the toner T, and regulates the thickness of the toner layer carried on the outer peripheral surface of the toner carrier 31 It consists of a blade 32.

The doctor blade 32 holds the toner carrier 3
The first printing position is provided on the upstream side in the rotation direction of the toner carrier 31 so as to contact the toner carrier 31 with a predetermined pressure.

The toner T is, for example, particles of about 10 μm mainly composed of styrene acrylic, and is agitated and transported in the vicinity of the doctor blade 32 and the supply roller 33.
A negative charge is provided. The configurations of the toner carrier 31, the doctor blade 32, and the supply roller 33 are not particularly limited in the present invention.

The toner carrier 31 is driven by a driving device (not shown), and rotates at a speed of, for example, 60 mm / sec on the surface in the direction of the arrow in the figure. Further, the toner carrier 31 is connected to a toner carrier voltage applying means 72 capable of applying a voltage at a predetermined cycle and voltage.

The toner carrier 31 has irregularities of several μm on its surface, and the toner T is pressed against the irregular surface of the toner carrier 31 by a doctor blade 32. Thus, the toner carrier 31 can carry the toner T on its outer peripheral surface. The rotation speed of the toner carrier 31 is not particularly limited.

The printing unit 1 is composed of a flight control unit 2 and an opposing electrode 11 which face the outer peripheral surface of the toner carrier 31. By applying a voltage to the ring-shaped control electrode 23 according to an image signal, From the toner carrier 31 to the counter electrode 1
The passage of the toner T with respect to the gate 22 in one direction is selectively controlled.

On the other hand, the recording material P is accommodated in the recording material accommodating section 40, sent out by the pickup roller 41 in response to a print start signal from the controller section 7, and conveyed by the registration roller 42. The recording material P conveyed by the registration rollers 42 is fed to a paper feed guide plate 43 and a paper pressing plate 4.
By 4, it is transported in close contact with the counter electrode 11.

The counter electrode 11 is provided such that the distance from the outer peripheral surface of the toner carrier 31 is, for example, 1 mm. Further, the counter electrode 11 is provided with a counter electrode voltage applying means 7.
1, a high voltage of 2 kV is applied during a printing operation, for example. That is, the counter electrode 11 and the toner carrier 3
1, an electric field necessary for causing the toner T carried on the toner carrier 31 to fly in the direction of the counter electrode 11 is formed by applying a voltage to the counter electrode 11 by the counter electrode voltage applying means 71. I have. The distance between the counter electrode 11 and the toner carrier 31 is not particularly limited. Further, the voltage applied to the counter electrode 11 is not particularly limited.

The controller unit 7 includes a main control unit that controls the entire image forming apparatus (not shown), in addition to the counter electrode voltage applying unit 71, the toner carrier voltage applying unit 72, and the control electrode voltage applying unit 73. An image processing unit for converting the converted surface image data into a format of image data to be printed, an image memory for storing the converted image data, and providing image data obtained from the image processing unit to the flight control unit 2 And an image forming control unit for converting the image data to the desired image data.

The flight controller 2 has a structure that is two-dimensionally spread in parallel with the counter electrode 11 and opposed to the counter electrode 11 so that toner can pass from the toner carrier 31 toward the counter electrode 11. Has become. The electric field applied to the toner layer on the toner carrier 31 changes according to the potential applied to the control electrode 23, and the flying of the toner T from the toner carrier 31 to the counter electrode 11 is controlled.

The control electrode 23 is provided so that the distance from the outer peripheral surface of the toner carrier 31 is, for example, 100 μm, and is fixed and held by the electrode mount 21. As shown in FIG. 4, the flight control unit 2 has a configuration in which a control electrode 23 and a lens electrode 26 are arranged via an insulating layer.

The insulating layer is made of, for example, a polyimide resin and has a thickness of 25 μm.
A hole to be a gate 22 described later is formed.

The control electrode 23 is made of, for example, a copper foil having a thickness of 18 mm, is provided around the hole, and is arranged according to a predetermined arrangement. The opening of each hole is formed to have a diameter of, for example, 160 μm.
And a passage portion of the toner T flying from the front to the counter electrode 11. Hereinafter, this passage portion is referred to as a gate 22. The distance between the control electrode 23 and the toner carrier 31 is
There is no particular limitation. The control electrode 23 is provided with an opening having an opening diameter of 200 μm. However, the diameter of the opening, the size of the gate 22, and the materials and thicknesses of the insulating layer and the control electrode 23 are not particularly limited. It is not something to be done.

The control electrode 23 is electrically connected to the control electrode voltage applying means 73 via the power supply line 24. Further, the control electrode 23 is disposed on an insulating base material,
Thereby, the insulation between the control electrodes 23 and the power supply lines 2
4, insulation between each control electrode 23 and each power supply line 24 that are not connected to each other, and insulation between the toner carrier 31 and the counter electrode 11 are ensured.

A pulse corresponding to an image signal, that is, a voltage, is applied to the control electrode 23 of the flight control section 2 by the control electrode voltage applying means 73. That is, the control electrode voltage applying means 73 applies, for example, 300 V to the control electrode 23 when the toner T carried on the toner carrier 31 passes in the direction of the counter electrode 11 (hereinafter referred to as ON potential), and does not allow the control electrode 23 to pass. In this case (hereinafter, OFF potential), for example, 0 V is applied.

Incidentally, the lens electrode 26 on the side of the counter electrode 11 via the insulating layer of the control electrode 23 is appropriately disposed for the purpose of rectifying the toner flow after passing through the control electrode 23 and the like. As described above, when the potential applied to the control electrode 23 is controlled in accordance with the image signal, and the recording material P is arranged on the surface of the opposite electrode 11 facing the toner carrier 31, the image signal is applied to the surface of the recording material P. A corresponding toner image is formed. The control electrode voltage applying means 73 is controlled by a control electrode control signal sent from an image forming control unit (not shown) of the controller unit 7.

The above-described image forming apparatus can be used not only as a printer for outputting from a computer or a word processor but also for printing a digital copy. I do.

(First Embodiment) First, when an image signal from a host computer (not shown) is sent to the controller section 7, the controller section 7 converts the image signal into a print start signal and a control signal such as a recording material size. The image data is separated into image data, and first, the pickup roller 41 is rotated by the print start signal, and the recording material P stored in the recording material storage unit 40 is sent out until it comes into contact with the registration roller 42. At this time, the operation of the pickup roller 41 is performed after it is confirmed that the recording material P is present by a recording material detection sensor (not shown) that detects the presence or absence of the recording material provided in the recording material storage unit 40. Begin.

Next, the registration roller 42 starts rotating at a constant speed, and the recording material P is conveyed to the counter electrode 11 while being pressed against the paper feed guide plate 43 by the paper press plate 44 at a constant speed.

Processing of image signals is started by the image forming control unit of the controller section 7 in synchronization with the start of the rotation operation of the registration roller 42, but the recording material P is conveyed from a state in which it is in contact with the registration roller 42. Therefore, the image forming position from the leading end of the recording material P is calculated in the image forming control unit, and printing can be performed at a predetermined position on the recording material P.

Next, the operation of the flight control unit will be described with reference to FIGS. The toner T charged to a predetermined polarity (negative in this embodiment) by stirring and rubbing between the doctor blade 32 and the supply roller 33 is transferred to the toner carrier 3.
By the rotation of 1, the sheet is conveyed to a position facing the gate 22 of the flight control unit 2.

Here, when a printing voltage (+300 V in the present embodiment) is applied to the control electrode 23, the toner T flies toward the control electrode 23 including the opening of the gate 22. At this time, the counter electrode 11 is
From the toner carrier 31. Therefore, of the toner T flying toward the control electrode 23, the toner T in a range near the gate 22 passes through the gate 22, flies toward the counter electrode 11, and moves on the counter electrode 11. A toner image is formed thereon.

At this time, since the gap between the surface of the toner layer on the toner carrier 31 and the electrode substrate 25 is about several tens of μm, the toner T colliding with the electrode substrate 25 is affected by van der Waals force or the like. Will adhere as it is.

Here, when +200 V having a polarity opposite to that of the toner is applied to the toner carrier 31 in synchronization with the start of the non-printing cycle of the print clock pulse, the adhered toner is
From the toner carrier 31.

In the present embodiment, three control electrodes 23
00V, 500μsec printing cycle, 0V, 1500
A non-printing cycle of μsec is taken and the toner carrier 3
200V, 1000 in synchronization with the start of the non-printing cycle
A voltage of 0 sec was applied, and a voltage of 0 V was applied over a period prior to the start of a printing cycle and over the printing period.

(Second Embodiment) The operation of this embodiment will be described with reference to FIGS. In addition,
The operation until the recording material P is conveyed to the counter electrode 11 is the same as in the first embodiment, and the operation in the flying section will be described.

The toner T charged to a predetermined polarity (negative in this embodiment) by stirring and rubbing between the doctor blade 32 and the supply roller 33 is rotated by the rotation of the toner carrier 31 so that the gate 22 of the flight controller 2 Is conveyed to a position facing.

Here, when a printing voltage (+300 V in the present embodiment) is applied to the control electrode 23, the toner T flies toward the control electrode 23 including the opening of the gate 22. At this time, the counter electrode 11 is
From the toner carrier 31. Therefore, of the toner T flying toward the control electrode 23, the toner T in a range near the gate 22 passes through the gate 22, flies toward the counter electrode 11, and moves on the counter electrode 11. A toner image is formed thereon.

At this time, since the gap between the surface of the toner layer on the toner carrier 31 and the electrode substrate 25 is about several tens of μm, the toner T colliding with the electrode substrate 25 is affected by van der Waals force or the like. Will adhere as it is.

Here, the first non-printing voltage -200 V is applied to the control electrode 23 for 500 μsec by the offset driver circuit 73b of the control electrode voltage applying means 73 in synchronization with the start of the non-printing cycle of the print clock pulse. ,
A second non-printing voltage of 0 V is applied for 1000 μsec. However, during the printing period, the offset driver circuit 73b has the second non-printing voltage, and the data driver circuit 73a supplies the control electrode 23 with the data driver circuit 73a in accordance with the image signal.
V or 0 V is applied.

(Third Embodiment) The operation of this embodiment will be described with reference to FIGS. In addition,
The operation until the recording material P is conveyed to the counter electrode 11 is the same as in the first embodiment, and the operation in the flying section will be described.

The toner T charged to a predetermined polarity (negative in this embodiment) by stirring and sliding between the doctor blade 32 and the supply roller 33 is rotated by the rotation of the toner carrier 31 so that the gate 22 of the flight controller 2 Is conveyed to a position facing.

In this embodiment, the shield electrode 27 is provided on the toner carrier 31 side with respect to the control electrode 23 via an insulating layer so as to face the toner carrier 31. The collision of the toner T with the control unit 2 is limited to the vicinity of the gate 22.

Here, when a printing voltage (+300 V in this embodiment) is applied to the control electrode 23, the toner T flies toward the opening of the gate 22. At this time, the electric field from the counter electrode 11 enters the gate 22 serving as the opening so as to go around in the direction of the toner carrier 31.

For this reason, the toner T which has flown toward the control electrode 23 of the gate 22 passes through the gate 22 and flies toward the counter electrode 11, and forms a toner image on the recording material P which moves on the counter electrode 11. Form. At this time, the toner carrier 31
Since the upper surface of the toner layer and the electrode substrate 25 have a gap of about several tens of μm, the toner T in contact with the electrode substrate 25 adheres as it is due to the action of van der Waals force or the like.

Here, when −200 V having the same polarity as the toner is applied to the shield electrode 27 in synchronization with the start of the non-printing cycle of the print clock pulse, the adhered toner is removed from the electrode substrate 25.
From the toner carrier 31. In the present embodiment, 300 V, 500 μs
ec and a non-printing cycle of 0 V and 1500 μsec, and a voltage of −200 V and 500 μsec is applied to the shield electrode 27 in synchronization with the start of the non-printing cycle, and a period prior to the start of the printing cycle, and A voltage of 0 V was applied over the printing period.

In this embodiment, a rotating cylindrical sleeve is used as the toner conveying means. However, if the electrode can be arranged on the toner carrier side facing the control electrode 23, a belt or a traveling The transfer may be performed using a wave electric field, a mechanical traveling wave, air, or the like.

The image forming apparatus according to the present invention can be suitably applied to, for example, a printing unit of a digital copying machine and a facsimile machine, a digital printer, a plotter, and the like.

[0090]

According to the first aspect of the present invention, although the developer (toner) carrier, the control electrode, and the counter electrode have a simple structure, immediately after the end of the toner flying operation during the printing period, An electric field is applied to the toner carrier to attract the toner, and the toner attached to the flight controller and the toner layer formed on the toner carrier and the toner floating on the flight control electrode and gate are not printed. Since an action of returning to the direction of the toner carrier occurs at the same time as the start of the cycle, not only the adhered toner is removed but also the deterioration of the image quality due to the floating toner can be prevented.

Further, prior to the printing period of the control electrode,
Since the voltage is such that sufficient toner flight can be obtained when a printing voltage is applied during the printing period, extremely efficient flight conditions can be obtained.

In the apparatus according to the second aspect, when the voltage application time of the polarity opposite to that of the toner to the toner carrier is tC, the printing time is tB, and the non-printing time is tW, ｔt
By setting B <tC <tW and tB <tW, the toner adhered to the flight control unit is efficiently returned to the toner carrier side,
Further, an effect is obtained that the flying is performed efficiently even during printing.

In the apparatus according to the third aspect, the effect of returning the floating and adhered toner to the side of the toner carrier can be obtained by applying the toner suction electric field toward the toner carrier during the non-printing period. At this time, it is not preferable to apply an electric field higher than the flying electric field at the time of printing to the toner carrier side, because this causes strong adhesion of the toner to the toner carrier side.

In the device according to the fourth aspect, since the voltage applying means of the toner carrier and the voltage applying means of the control electrode can be set to a common reference potential, the control circuit for both applied voltages can be simplified, and The effect that a safe and stable operation can be obtained is obtained.

In the apparatus according to the fifth aspect, by setting the voltage level in two stages during the non-printing period of the control electrode, the toner can be applied to the flight control electrode only by the voltage application means of the control electrode. An effect of removing toner and preventing adhesion can be obtained, and a sufficient flying amount can be obtained during a printing period.

In the apparatus according to the sixth aspect, the non-printing period is set longer than the printing period, and an electric field which repels the toner against the control electrode after the printing jumps and an electric field which repels the toner before the printing period. By setting the electric field weaker than the above electric field, an effect of reliably removing the toner from the control electrode and an effect of achieving a transition to a smooth flight at the start of the printing period are obtained.

In the apparatus according to the present invention, by applying a voltage having the same polarity as that of the toner for at least half the printing time, the attached and floating toner is returned to the toner carrier. By applying the second voltage for a half or more of the printing time prior to the print flying operation, the kinetic force of the toner in the direction of the toner carrier is eliminated, and the print flying can be efficiently performed. The effect of flying is obtained.

In the apparatus described in claim 8, the second
By setting the non-printing voltage to the same potential as the voltage applied to the toner carrier, the flying electric field between the control electrode for controlling the toner flight and the toner carrier can be made almost zero, and the toner in the next printing period Can be efficiently performed.

Further, since the toner has kinetic energy in the direction of the toner carrier due to the application of the first voltage applied prior to the application of the second voltage, even if the operation is shifted to the application of the second voltage, the toner The effect of not floating away from the carrier is obtained.

In the apparatus according to the ninth aspect, the shield electrode is disposed on the toner carrier side of the control electrode for controlling the toner flight in accordance with the image signal so as to face the toner carrier via an insulating layer. This can eliminate the influence of the electric field on the toner layer on the toner carrier of the control electrode other than the gate portion regardless of the printing and non-printing periods.

Further, by applying a voltage having the same polarity as that of the toner to the shield electrode during the non-printing period, the toner floating and adhering near the gate portion during the printing period can be separated from the shield electrode, ie, near the gate portion. Can be

In the apparatus according to the tenth aspect, the application time of the same polarity as that of the toner to the shield electrode is set to ｔ tB.
By doing so, the toner floating and adhering between the electrode substrate and the toner layer near the gate portion and on the toner carrier can be separated from the electrode substrate, and the voltage applied to the shield electrode before the printing period can be reduced. By returning to the same voltage as in the printing period, the kinetic energy of the toner in the direction away from the gate portion and the electrode substrate prior to the printing flight operation is eliminated, and the printing flight is performed efficiently during the printing flight.

In the apparatus according to the eleventh aspect, by setting the voltage applied to the shield electrode to be equal to or less than the voltage applied to the control electrode, the electric field in which the toner returns from the shield electrode toward the toner carrier can be optimized. .

In the apparatus according to the twelfth aspect, the applied voltage of the shield electrode during the printing period is the same as the applied voltage of the control electrode during the non-printing period. The effect is obtained that an electric field that attracts toner in the direction does not act.

Further, since the reference potential of the control electrode and the reference potential of the shield electrode can be the same, safe and reliable control can be performed with a simple circuit configuration.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram illustrating a structure of a printing unit of the image forming apparatus employing the present invention.

FIG. 3 is a schematic diagram of a printing unit in the image forming apparatus employing the present invention.

FIG. 4 is a plan view of a flight control electrode used in the present invention.

FIG. 5 is a perspective view of a flight control electrode used in the present invention.

FIG. 6 is a perspective view of a flight control electrode provided with a shield electrode according to the present invention.

FIG. 7 is a perspective view of another flight control electrode provided with a shield electrode according to the present invention.

FIG. 8 is a timing chart illustrating a printing operation according to the present invention.

FIG. 9 is a block diagram showing a structure of a printing unit according to the present invention.

FIG. 10 is a timing chart illustrating another embodiment according to the present invention.

FIG. 11 is a block diagram showing the structure of another embodiment according to the present invention.

FIG. 12 is a timing chart illustrating another embodiment according to the present invention.

FIG. 13 is a block diagram showing the structure of another embodiment according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printing part 2 Flight control part 3 Toner supply part 4 Paper supply part 6 Fixing part 7 Controller part 11 Counter electrode 21 Electrode mounting base 22 Gate 23 Control electrode 24 Power supply line 25 Electrode board 26 Lens electrode 31 Toner carrier 32 Doctor blade 33 Supply roller 34 Stirring roller 35 Toner storage tank 40 Recording material storage part 41 Pickup roller 42 Registration roller 43 Paper feed guide plate 44 Paper press plate 61 Heater 62 Heat roller 63 Pressure roller 64 Temperature sensor 71 Counter electrode voltage applying means 72 Toner carrier Voltage applying means 73 Control electrode voltage applying means

Claims (12)

[Claims] 1. A developing agent carrier for carrying a developing agent charged to a predetermined polarity, and a developing agent disposed at a predetermined gap from the developing agent carrier and passing the developing agent on the developing agent carrier A plurality of gate means, a control electrode disposed so as to surround the gate means and capable of applying a predetermined voltage, and a predetermined voltage which is disposed opposite to the developer carrier of the control electrode and is opposed to the developer carrier. And a voltage for giving a state in which the developer passes or does not pass from the gate means to the control electrode and the counter electrode based on the print cycle and the non-print cycle of the print clock pulse. An image forming apparatus provided with a voltage applying means capable of applying the developer, comprising: a developer carrier voltage applying means for applying a predetermined voltage to the developer carrier; and a non-printing cycle of the print clock pulse. Synchronize with the start, the developer carrier voltage application From to 該顕 image carrier, an image forming apparatus, wherein a charging polarity opposite the polarity of the voltage of the developer with a control means for applying a short period of time than non-printing period. 2. The time for applying an applied voltage having a polarity opposite to the charging polarity of the developer to the developer carrier is tC, the printing time is tB,
When the non-printing time is tW, tB <tW and 1 / 2t
2. The image forming apparatus according to claim 1, wherein B <tC <tW. 3. An applied voltage having a polarity opposite to that of the developer applied to the developer carrier, which is lower than an applied voltage at the time of printing to the control electrode, and an applied voltage to the control electrode at the time of non-printing. The image forming apparatus according to claim 1, wherein the image forming apparatus is higher than the image forming apparatus. 4. The image forming apparatus according to claim 3, wherein the voltage applied to the developer carrier during non-printing is substantially the same as the voltage applied to the control electrode during the non-printing period. apparatus. 5. A developer carrier for carrying a developer charged to a predetermined polarity, and a developer carrier disposed at a predetermined gap from the developer carrier and passing the developer on the developer carrier. A plurality of gate means, a control electrode disposed so as to surround the gate means and capable of applying a predetermined voltage, and a predetermined voltage which is disposed opposite to the developer carrier of the control electrode and is opposed to the developer carrier. And a voltage for giving a state in which the developer passes or does not pass from the gate means to the control electrode and the counter electrode based on the print cycle and the non-print cycle of the print clock pulse. An image forming apparatus provided with a voltage applying means capable of applying the developer, comprising: a developer carrier voltage applying means for applying a predetermined voltage to the developer carrier; and a non-printing cycle of the print clock pulse. Synchronously with the start, the first non-polarity of the same polarity as the developer Shaped voltage and, an image forming apparatus characterized by comprising a control means for applying a first second non-printing voltage absolute value is smaller than the non-printing voltage. 6. An application time for printing applied to the control electrode is tB, an application time for non-printing is tW, a first non-printing time is tC1, and a second non-printing time is tC2.
6. The image forming apparatus according to claim 5, wherein <tW and tW = tC1 + tC2. 7. When the application time during printing applied to the control electrode is tB, the first non-printing time is tC1, and the second non-printing time is tC2, 1 / 2tB <tC1 and 1 / 2t
7. The image forming apparatus according to claim 6, wherein B <tC2. 8. The image forming apparatus according to claim 7, wherein the second non-printing voltage has substantially the same voltage value as the voltage applied to the developer carrier. 9. A developer carrying member for carrying a developer charged to a predetermined polarity, and a developing agent disposed at a predetermined gap from the developer carrying member and passing the developer on the developer carrying member. A plurality of gate means, a control electrode disposed so as to surround the gate means and capable of applying a predetermined voltage, and a predetermined voltage which is disposed opposite to the developer carrier of the control electrode and is opposed to the developer carrier. And a voltage for giving a state in which the developer passes or does not pass from the gate means to the control electrode and the counter electrode based on the print cycle and the non-print cycle of the print clock pulse. An image forming apparatus provided with a voltage applying means capable of applying voltage, wherein a conductive layer is disposed on the developer carrier side via the control electrode and the insulating material so as to face the developer carrier; In synchronization with the start of the non-printing cycle of the printing clock pulse, An image forming apparatus characterized by comprising control means for applying only a voltage of the same polarity, shorter period of time than non-printing period. 10. When the time for applying a voltage of the same polarity as the developer to the conductive layer provided on the developer carrier side of the control electrode is tS, the printing time is tB, and the non-printing time is tW, 1 / 2t
The image forming apparatus according to claim 9, wherein B <tS <tW and tB <tW. 11. An absolute value of an applied voltage having the same polarity as that of a developer applied to a conductive layer at the time of non-printing is smaller than an absolute value of an applied voltage at the time of printing to a control electrode. 11. The image forming apparatus according to claim 10, wherein the applied voltage is larger than the absolute value of the applied voltage during non-printing. 12. The voltage applied to the conductive layer provided on the developer carrier side of the control electrode during printing is substantially the same as the voltage applied to the control electrode during the non-printing period. Item 12. The image forming apparatus according to Item 11.