JP2002287484A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that image quality is easily deteriorated by the scattering of toner. SOLUTION: The electrified toner T is carried toward one end side of a carrying base plate 30 along the carrying surface of the base plate 30 by electrostatic force, and the toner is made to fly from one end side of the base plate 30 toward a photoreceptor drum 1, then toner cloud 53 is formed by the toner made to fly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus for developing a latent image on a latent image carrier to form an image.

[0002]

2. Description of the Related Art As an image forming apparatus such as a copying machine, a printer, and a facsimile, a latent image is formed on a latent image carrier using an electrophotographic process, and a developer (hereinafter, referred to as "toner") is formed on the latent image. In some cases, an image is formed by adhering and developing a visible image, and transferring this toner image to a recording medium (transfer paper).

In such an image forming apparatus, as a developing device for developing a latent image, conventionally, a toner stirred in the developing device is carried on a surface of a developing roller which is a developer carrying member, and the developing roller is rotated. The latent image carrier is conveyed to a position facing the surface of the latent image carrier, and the latent image on the latent image carrier is developed. After the development, the developer or toner not transferred to the latent image carrier is rotated by a developing roller. In such a case, a developer or toner is newly stirred and charged, and is again carried on a developing roller and transported.

A developing device is disclosed in Japanese Patent Laid-Open No. 5-19 / 1993.
As described in Japanese Patent Application Laid-Open No. 615, the toner is conveyed on the surface of the developing roller using electrostatic force, and the toner is separated from the surface of the developing roller by suction force generated between the latent image carrier and the latent image carrier. Using a transfer substrate that transfers toner with electrostatic force, as described in JP-A-59-181375, or the like, which is made to adhere to the surface,
In some cases, the toner is transported to a position facing the latent image carrier, and the toner is separated from the transport surface by suction force generated between the toner and the latent image carrier and adheres to the surface of the latent image carrier.

[0005]

However, in an image forming apparatus in which toner is adhered to a latent image carrier using the above-mentioned developing roller, the toner is attracted from the developing roller by electrostatic attraction of a strong electric field or AC voltage. Since the toner is adhered to the latent image carrier and developed, the dents of the latent image carrier with brushes, spikes and scattering of toner are liable to occur, and the background is stained. In particular, at the time of development, since the small charged toner adheres to the latent image carrier regardless of the amount of charge of the toner, the charged toner having a small adhesive force with the latent image carrier during the development process. However, there is a problem that is easily scattered.

Further, when the toner is charged by friction charging or corona discharge charging, saturated charged toner and unsaturated charged toner are mixed and have a large charge distribution. When such a toner is forcibly transferred to the developing roller using a magnetic brush or a transfer roller, the developer once carried on the developing roller at the developing speed of the developing roller (about 100 cm / sec linear velocity) Among them, there is a problem that the toner having a small charge is detached, the toner is scattered, and the formed image is easily stained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an image forming apparatus which has a simple structure, has a small amount of toner scattering, and can obtain high image quality.

[0008]

In order to solve the above-mentioned problems, an image forming apparatus according to the present invention has a space advance for conveying charged toner toward one end side by electrostatic force along a conveying surface. A carrier substrate having a plurality of electrodes for generating a wave electric field, and causing the toner to fly from one end side toward the latent image carrier; and a means for generating a toner cloud by the toner flying from one end side of the carrier substrate. It is provided with.

Here, it is preferable that a pair of opposed transfer substrates and a means for generating an alternating electric field between electrodes at one end of the opposed transfer substrates are provided. It is preferable that a pair of opposed transfer substrates and an intermediate transfer substrate facing the pair of opposed transfer substrates are provided.

Further, it is preferable to have a reverse transport substrate that transports the toner toward the other end side by electrostatic force along the transport surface in opposition to the transport substrate. Further, it is preferable to have a toner gutter for collecting toner not used for development. The toner gutter preferably has a reverse transport member for transporting the collected toner in the reverse direction.

Further, it is preferable that a means for generating a DC electric field between the electrode of the transfer substrate and the latent image carrier is provided. Further, it is preferable that a means for generating a DC electric field is provided between the electrode provided on the outer surface side of the transfer substrate and the latent image carrier.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an image forming apparatus according to a first embodiment of the present invention will be described with reference to FIG.
FIG. 1 is an overall schematic configuration diagram of the image forming apparatus.
The general outline and operation of this image forming apparatus will be described.
The photoconductor drum 1 (for example, an organic photoconductor: OPC) as a latent image carrier is driven to rotate clockwise in FIG. When a document is placed on the contact glass 2 and a print start switch (not shown) is pressed, the document illumination light source 3 and the mirror 4 are pressed.
The scanning optical system 5 including the mirror 6 and the scanning optical system 8 including the mirrors 6 and 7 move to read a document image.

Here, the scanned original image is read as an image signal by an image reading element 10 arranged behind the lens 9, and the read image signal is digitized and processed. Then, a laser diode (LD) is driven by the image-processed signal, and a laser beam from the laser diode is reflected by a polygon mirror 13 and then radiated onto the photosensitive drum 1 via a mirror 14.
The photosensitive drum 1 is uniformly charged by the charging device 15, and an electrostatic latent image is formed on the surface of the photosensitive drum 1 by writing with a laser beam.

The electrostatic latent image on the surface of the photoreceptor drum 1 is visualized with toner adhered thereto by the developing device 16 according to the present invention, and the visible image is supplied from the paper feeding unit 17A or 17B. The toner image is transferred to the transfer paper (recording medium) 19 fed by the feed rollers 18A or 18B by corona discharge of the transfer charger 20. Transfer paper 19 to which this visible image has been transferred
Is separated from the surface of the photosensitive drum 1 by the separation charger 21, is conveyed by the conveyance belt 22, passes through the pressure contact portion of the fixing roller pair 23, and fixes the visible image to the paper discharge tray 24 outside the machine. Is discharged.

On the other hand, the toner remaining on the surface of the photosensitive drum 1 after the transfer is removed by the cleaning device 25, and the charge remaining on the surface of the photosensitive drum 1 is erased by the charge removing lamp 26.

Next, the developing device 16 will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of the developing device. The developing device 16 transports the charged toner toward one end (hereinafter, also referred to as a “flying side”) by electrostatic force along the transport surfaces 30a, 30a of the transport substrates 30, 30 facing each other. A toner flying device 31 is provided for flying toner from one end of each of the photosensitive drums 30 to the photosensitive drum 1 as a latent image carrier.

The toner charged between the transfer substrates 30 of the toner flying device 31 is transferred to the toner box 3.
2 and a charging roller 34 for charging the toner supplied to the toner box 32
A charging blade 35 disposed in contact with the peripheral surface of the charging roller 34; and an agitator 37 for transporting the toner in the toner hopper 36 to the vicinity of the charging roller 34.

Further, the transfer board 3 of the toner flying device 31
Toner gutters 38, 38, which are collection means for collecting unused toner that has been used by flying from 0, 30;
Reverse transport path members 39, 39, etc., for transporting the toner collected by the toner gutter 38 to the toner box 32 in the reverse direction by electrostatic force and returning the same are provided.

The transport substrate 30 constituting the toner flying device 31 in the developing device 6 will be described with reference to FIGS. FIG. 3 is a schematic sectional view of the transfer board, and FIG. 4 is a plan view of the transfer board.
The transport substrate 30 is a set of a large number of three electrodes 42, 42,... For generating a spatially traveling wave electric field for transporting the toner with electrostatic force on a long flat support substrate 41. A transfer surface forming member 4 for forming a transfer surface
3, a surface coat layer 44 for reducing the contact resistance with the toner is formed on the surface of the conveyance surface forming member 43, and the toner is conveyed along the conveyance surface while being accelerated by electrostatic force.

Here, as the support substrate 41, an insulating film such as SiO ₂ is formed on 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. Can be used. Here, a glass substrate having a thickness of 0.9 to 1.1 mm was used.

The electrode 42 is formed on the support substrate 41 by Al, Ni
A conductive material such as -Cr is formed in a thickness of 0.1 to 0.2 [mu] m, and is patterned into an electrode shape using a semiconductor technology such as a photolithography technology. It is preferable that the arrangement density of the electrodes 42 be 1/3 to 100 times the line diameter (L / S) of the toner diameter in order to ensure a good conveyance speed and amount. / 2 to 5 times. Further, it is preferable that the width of the electrode 42 is 1 to 3 times as large as the toner diameter in order to ensure a good conveyance speed and a good conveyance amount.

Therefore, as shown in FIG.
They are arranged in a direction orthogonal to the toner flying / conveying direction, and are arranged with the arrangement density being increased stepwise (narrowing the arrangement interval) along the toner flying / conveying direction. That is, for example, from the toner supply side to the toner flying side, the area A
In the area B, the electrodes 42 are arranged at intervals of 100 μm.
Are arranged at intervals of 20 μm, the electrodes 42 are arranged at intervals of 10 μm in the region C, and the electrodes 42 are arranged at intervals of 5 μm in the region D.
Further, the width of the electrode 42 is set to 10 μm with the average particle diameter of the toner being 8 μm.

As the transfer surface forming member 43, an insulating film having a large relative dielectric constant, for example, SiO ₂ (silicon oxide film) or Ta ₂ O ₅ (tantalum pentoxide, relative dielectric constant 28) is formed to a thickness of 0.5 to 1 μm. It is formed by forming a thick film. In the case of using the polyimide, but the polyimide is the relative dielectric constant of about 3.6, BaTiO ₃ when coated on a substrate
By adding about 1% of these fine particles, the apparent relative dielectric constant becomes 10 to 12.

By increasing the relative dielectric constant of the conveying surface forming member 43, the driving voltage can be reduced, and the driving recoil of the particles (toner) and the conveying speed can be increased. Therefore, in order to more reliably transport the charged toner at a low voltage and at a speed at which the toner can fly, the transport surface forming member 43 is preferably formed of a material having a relative dielectric constant of 10 or more. When an experiment was performed using a polyimide film having a thickness of 1 μm, a scanning drive voltage of 500 V DC was required. However, when about 1% of BaTiO ₃ fine particles were added as described above, considerable results were obtained at a drive voltage of 300 V. Obtained.

The surface coat layer 44 is a film having a function of reducing the contact resistance between the transfer surface and the interface of the charged toner, and is made of, for example, a fluororesin material such as PTFE and PFA.
It is formed by coating with a thickness of about 0.3 μm.

Here, the number of the transfer substrates 30 constituting the toner flying device 31 may be one, but in this embodiment, the transfer surfaces 30a, 30a of the transfer substrate 30 are formed by using the two transfer substrates 30, 30. They are arranged facing each other. At this time, the facing distance between the two transfer substrates 30, 30 is 30 to
The range is 200 μm.

By using a plurality of transfer substrates 30 in this manner, the amount of toner that can be transferred and fly per unit time can be increased, and by selecting the drive transfer substrate 30 to be driven, the transfer and flying can be performed. The amount of toner to be controlled can be controlled.

The transport path member 33 and the reverse transport path member 3
9 also has the same basic configuration as the transfer substrate 30 described above. Although not shown here, a large number of electrodes are arranged at predetermined intervals on an insulating flexible substrate as a support substrate, and further a transfer surface is formed. The conveying surface forming member is laminated, and a surface coat layer for reducing contact resistance with toner is formed on the surface of the conveying surface forming member. These transport path members 3
In the third and reverse transport path members 39, the arrangement density of the electrodes is substantially equal.

Next, the transfer board 3 of the toner flying device 31
The toner transport and flying (ejection) operations according to 0 and 30 will be described with reference to FIGS. First, in the toner flying device 31, as shown in FIG. 5, three electrodes 42, 42, 42 of the transport substrates 30, 30 are set as one set, and a three-phase drive voltage (drive waveform) is applied to each electrode 42. V
Drive circuits (drivers) 50, 50 for applying electrodes a, Vb, and Vc, respectively, are provided. The drive waveforms Va, Vb, and Vc output from the drive circuit 50 each have a slight delay time, and the drive waveforms Va, Vb, and Vc have three values of + potential, − potential, and 0 potential (not applied), respectively. FIG.

Here, as shown in FIG.
On the upper side, there is a negatively charged toner T, and “+”,
When “−”, “0”, “+”, and “−” are applied, and the negatively charged toner T is positioned on the “0” electrode 42, the negatively charged toner T Since a repulsive force acts on the electrode 42 and a suction force acts on the right "+" electrode 42, the negatively charged toner T moves to the "+" electrode 42 side.

Then, for example, the three-phase driving voltages Va, Vb,
When Vc is applied to each of the three electrodes 42, the voltages applied to the plurality of continuous electrodes 42 of the transfer substrate 30 are "0", "+", "-", and "0", respectively, as shown by. ,
It changes like "+". Therefore, no force acts between the electrode 42 changed from “+” to “0” and the negatively charged toner T, and the negatively charged toner T changes from “0” to “−”.
The repulsive force between the negative electrode 42 and “−” changes from “−” to “+”.
The negatively charged toner T further moves toward the “+” electrode 42 because the suction force acts between the negative electrode 42 and the negative electrode 42.

As described above, by changing the potential of the driving waveform applied to the electrode 42 and apparently moving the driving waveform, a space traveling wave electric field is generated, and the negatively charged toner T is moved to the "+" electrode 42 side. Since the toner T moves while being pulled, the negatively charged toner T is transported along the transport surface of the transport substrate 30. In the case of the positively charged toner, the toner can be conveyed by reversing the drive waveform change pattern. In the following, description will be made using negatively charged toner.

Here, as described above, the distance between the electrodes 42 is narrowed toward the one end (flying side) of the transport substrate 30, so that the negatively charged toner T has a stronger attraction force. The repulsive force acts, and the toner T
The transport speed increases stepwise (in the order of area A → area B → area C → area D in FIG. 4) toward the flight side, and the toner T finally flies from one end of the transport board 30 ( Is injected.)

The change patterns of the three-phase drive voltages Va, Vb, and Vc applied from the drive circuit 50 to the respective electrodes 42 of the transfer board 30 are not limited to the above example. For example, as shown in FIG. Without using “0”, the driving waveform for two consecutive electrodes 42 of the three electrodes 42 is “+”, and the driving waveform for the other electrode 42 is “−”.
However, the negatively charged toner T is transported to the transport substrate 30 while being accelerated along the transport surface, and flies from the flying side. When the flying toner speed was measured using the transport substrate 30 of the present embodiment, a flying speed of about 0.5 m / sec to 5 m / sec was obtained, depending on the applied voltage and frequency.

FIG. 9 shows the developing operation using the developing device 16 in the image forming apparatus constructed as described above.
This will be described with reference to FIG. First, as shown in the figure, the toner T negatively charged by the transfer substrates 30 of the toner flying device 31 of the developing device 16 is transported while being accelerated, and flies toward the photosensitive drum 1 from the flying side. As a result, the flying negatively charged toner T adheres to a portion (image portion) on the surface of the photosensitive drum 1 where positive charges exist, and the latent image is developed.

At this time, an AC voltage from an AC power supply 52 is applied to the electrodes 42 on one end (flying side) of the transfer substrates 30, 30, and an AC electric field (AC) is applied between the transfer substrates 30, 30. When an electric field is generated, the transfer substrate 30,
An AC electric field causes the toner T flying from 30 to become a cloud state, and a toner cloud 53 is generated, and the toner uniformly adheres to the latent image on the photosensitive drum 1, thereby improving image quality. That is, in this image forming apparatus, the electrodes 4 on one end (flying side) of the transfer substrates 30 and 30 are disposed.
2, 42 and the AC power supply 52 constitute a means for applying an AC electric field, which is a means for generating a toner cloud.

As described above, the charged toner is carried toward the one end by electrostatic force along the carrying surface of the carrying substrate, and the toner flies from one end of the carrying substrate toward the latent image carrier. In addition, the toner can be directly adhered without contact, so that the apparatus can be simplified and the cost can be reduced. Since the electrostatic toner is conveyed by the Coulomb force, the toner having a small charge amount, the toner having no charge, and the toner having the opposite polarity are not conveyed in a predetermined direction. As a result, the charge amount of the toner used for development is made uniform, the detachment of the toner in the development process is reduced, the background smear is reduced, and the image quality is improved.

Further, the deterioration of the toner is reduced as compared with the case where the developing roller is used as the developing means. That is, usually
The toner is charged by frictional charging, a film is formed on a developing roller together with a magnetic carrier, and the toner electrostatically attached to the carrier is formed into a magnetic brush, and is developed by being brought into contact with a latent image carrier. The mixture is kneaded by a developing roller, and is further pulverized into fine powder, SiO ₂ , TiO ₂
Additives are imprinted on the resin part of the toner.
Deterioration of the characteristics of the toner occurs, and a malfunction occurs. On the other hand, as described above, the toner is transported by the transport substrate and is caused to fly, so that the toner is further pulverized into fine powder, and additives such as SiO ₂ and TiO ₂ are added to the resin portion of the toner. No imprinting is performed, and characteristic deterioration is reduced.

Next, the toner collecting operation in the image forming apparatus will be described with reference to FIG. FIG. 3 is an explanatory diagram for explaining the toner collecting operation. As described above, the toner flies from the transfer substrates 30, 30 and adheres to the latent image area on the photosensitive drum 1, but not all of the toner is used for development.
Some toner flies from 0 but is not subjected to development.

Therefore, toner gutters 38, 38 are provided on the outer sides of the conveying substrates 30, 30, and the unused toner to be separated from the developing section is adhered and collected.
The toner gutters 38, 38 are provided with the reverse transport path members 39, 39 as described above.
9 and 39 can also transport the toner to the supply side (the other end side) by electrostatic force due to the spatially traveling wave electric field by the same configuration as the transport substrates 30 and 30 described above. It can be returned and re-used.

By providing the collecting means for collecting the unused toner flying from the transfer board 30 as described above,
The scattering of the toner can be reliably prevented, and the collection means is provided with a means for transporting the toner to the supply side by electrostatic force, so that the toner can be reused and the cost can be reduced.

When the bias voltage of the toner and the forward / reverse bias is alternately applied to the toner gutter 38, the toner is sucked and released, so that the scattered toner is collected and the collected toner is transported again. It can be returned to the flight side of the substrate 30 and reused. In this case, it is not always necessary to return the collected toner to the toner box section 32 by the reverse conveyance path member 39.

Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 2 is an explanatory view of a main part for explaining a developing device portion of the image forming apparatus. In this embodiment, a large number of electrodes 42 are used as the transfer substrates 30 and 30 of the toner flying device 31 of the developing device 16.
Are arranged along the transport direction at substantially equal intervals. Further, as the drive circuit 55, a three-phase drive waveform Va of three kinds of frequencies f1 is applied to each electrode 42 of the transfer substrate 30.
1, Vb1, Vc1, and a three-phase drive waveform V of frequency f2
a2, Vb2, Vc2 and frequency f3 (f1>f2> f
The one that outputs the three-phase drive waveforms Va3, Vb3, and Vc3 of 3) is used.

Then, the three-phase driving waveforms Va1, Vb1, Vc1 of the frequency f1 of the driving circuit 55 are applied to the electrodes 42, 42,...
Of the three-phase drive waveforms Va2, Vb2, and Vc2
, The electrodes f in the intermediate region of 0, the frequency f3
Of the three-phase drive waveforms Va3, Vb3, and Vc3
Are applied to the electrodes 42, 42,... In a required area on the 0 supply side. The other configuration is the same as that of the above embodiment, and the description and illustration are omitted.

With this configuration, the transfer substrate 3
Although the electrodes 42 and 42 of 0 and 30 are arranged at substantially equal intervals, the drive waveform V applied to each electrode 42 of the transfer substrate 30 is
The frequencies of a, Vb, and Vc increase stepwise (in this example, three steps of f3, f2, and f1) from the supply side to the flight side. Here, the suction force and the repulsion force acting on the charged toner change in a single time as the frequency of the drive waveform increases, so that the toner supplied from the supply side of the transport substrate 30 includes the electrodes 42, 42,. The higher the frequency of the driving waveform given to, the higher the moving speed, and therefore,
The toner is transported while being accelerated along the transport surface of the transport substrate 30 and flies from the flying side (one end side) toward the photosensitive drum 1.

As described above, when the toner is accelerated by changing the frequency of the drive waveform in a stepwise manner and applied, as compared with the case in which the arrangement density of the electrodes is changed as in the above embodiment, There is an advantage that the electrodes can be arranged at substantially equal intervals, but on the other hand, the configuration on the drive circuit side is slightly complicated. Therefore, which form should be adopted may be selected in consideration of the driving circuit and the manufacturing cost of the transfer board, and the arrangement density of the electrodes on the transfer board becomes narrower toward the flying side, and the drive waveform of the drive waveform is reduced. It is also possible to use a drive circuit whose frequency is increased stepwise.

Next, a third embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 3 is an explanatory view of a main part of a developing device portion of the image forming apparatus.
In this embodiment, as the transfer substrates 30 of the toner flying device 31 of the developing device 6, a plurality of electrodes 42 arranged at substantially equal intervals along the transfer direction are used. Also,
As the driving circuit 56, three-phase driving waveforms Vap1 and Vap of three kinds of peak values Vp1 are applied to the respective electrodes 42 of the transport substrate 30.
bp1, Vcp1 and a peak value Vp2 of a three-phase drive waveform V
ap2, Vbp2, Vcp2 and a peak value Vp3 (Vp1
>Vp2> Vp3) three-phase drive waveforms Vap3, Vbp
3, which outputs Vcp3.

Then, the three-phase drive waveforms Vap1, Vbp1, and Vcp1 of the peak value Vp1 of the drive circuit 56 are applied to the electrodes 42, 42,... Drive waveforms Vap2, Vbp2, Vc
.. p2 are transferred to the electrodes 42, 42,.
, The three-phase drive waveforms Vap3 and Vbp having the peak value Vp3
3, and Vcp3 are applied to the electrodes 42, 42,... In a required area on the supply side of the transfer substrate 30, respectively. The other configuration is the same as that of the above embodiment, and the description and illustration are omitted.

With this configuration, the transfer substrate 3
Although the 0, 30 electrodes 42, 42 are arranged at substantially equal intervals, the peak values of the drive waveforms Va, Vb, Vc applied to the respective electrodes 42 of the transport substrate 30 are increased from the supply side toward the flying side. It increases stepwise (in this example, three steps of Vp3, Vp2, and Vp1). Here, the attraction force and the repulsion force acting on the charged toner change in a single time as the peak value of the drive waveform increases, so that the toner supplied from the supply side of the transport substrate 30 is applied to the electrodes 42, 42. The moving speed increases as the peak value of the drive waveform given to... Increases, and therefore, the toner is conveyed while being accelerated along the conveying surface of the conveying substrate 30, and the photosensitive drum 1 is moved from the flying side (one end side). Fly towards.

Next, a fourth embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 3 is an explanatory view of a main part of a developing device portion of the image forming apparatus.
In this embodiment, as the transfer substrates 30 of the toner flying device 31 of the developing device 6, a plurality of electrodes 42 arranged at substantially equal intervals along the transfer direction are used. Also,
With the drive circuit 50 described above, the transport substrate 30
Of any of the electrodes 42 (here,
A drive circuit 5 that applies drive waveforms Vad, Vbd, and Vcd having a duty ratio higher than the three-phase drive waveforms Va, Vb, and Vc from the drive circuit 50 to the supply-side electrode 42).
7 is provided.

With such a configuration, the driving circuits 57 output driving waveforms Vad, Vbd, Vcd having a high duty ratio.
Is applied to the toner, the initial speed at which the toner flies from the transport substrate 30 is given, and the initial speed is substantially maintained by the electrostatic force of the electrode 42 to which the drive waveforms Va, Vb, and Vc from the drive circuit 50 are applied. , And flies from the flying side (one end side) of the transfer substrate 30 toward the photosensitive drum 1.

Next, a fifth embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 3 is an explanatory view of a main part of a developing device portion of the image forming apparatus.
The toner flying device 31 in this embodiment is similar to the transport substrate 30 described above, and has a transport substrate 3 having one surface as a transport surface.
0A and 30A, an intermediate transfer board 30B having both sides as transfer faces is disposed, and each transfer board 30A, 30A
The toner is transported and flies on two transport surfaces of the transport surface A and the intermediate transport substrate 30B.

With this configuration, the amount of toner that can be transported per unit time by the toner flying device 31 is twice that of each of the above-described embodiments, and can sufficiently cope with the amount of toner used in high-speed recording. . That is, as the recording speed increases, the amount of toner consumed depending on the image increases, and there is a case where the supply of toner required for development cannot be made in time. With such a configuration, a large amount of toner can be conveyed, so that the recording speed can be increased.

In this case, as shown in the figure, the intermediate transfer board 30B is disposed with the flight side retracted from the transfer boards 30A, 30A on both sides, and the AC power supply 52 supplies AC between the transfer boards 30A, 30A on both sides. An AC electric field is generated by applying a voltage to generate a toner cloud.

Next, a sixth embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 3 is an explanatory view of a main part of a developing device portion of the image forming apparatus.
In this embodiment, the transfer board 3 of the toner flying device 31 is used.
As described above, an AC voltage is applied from the AC power supply 52 between the electrodes 42, 42 at the flight side ends of the photoconductor drums 0, 30 and the flying side end of the photosensitive drum 1 and one (here, the lower side) of the transport substrate 30 A DC voltage is applied from a DC power supply 60, which is a means for generating a DC electric field between the electrodes 42 of the unit.

With such a configuration, for example, AC ± 300 V from the AC power supply 52 and DC
When 00V is applied, +500 V is always applied between the lower transfer board 30 and the photosensitive drum 1, and 200 V (= 500 − (+ 300)) and 8 are applied to the upper transfer board 30.
00V (500-(− 300)) is applied alternately, and the upper transfer substrate 30 and the photosensitive drum 1
And an electric field oscillation occurs due to the alternating electric field.

As a result, the toner cloud formed by the charged toner T flying from the transport substrates 30 of the toner flying device 31 is diffused by the electric field vibration due to the alternating electric field, and the toner cloud is formed between the toner cloud and the photosensitive drum 1. The frequency of attachment / detachment at the point is improved. Therefore, the toner can be attached to the target charge of the photosensitive drum 1 with higher accuracy, and the image quality is improved.

Next, a seventh embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 3 is an explanatory view of a main part of a developing device portion of the image forming apparatus.
In this embodiment, the transfer board 3 of the toner flying device 31 is used.
As described above, an AC voltage is applied from the AC power source 52 to the photosensitive drum 1 between the photosensitive drum 1 and the electrode portions 61, 61 provided on the outer surfaces of the transfer substrates 30, 30. A DC voltage from a DC power supply 60, which is a means for causing the DC voltage to flow, is applied.

With this configuration, each transport substrate 3
A DC bias electric field is generated between the photoconductor drum 1 and the photoconductor drum 1, and the toner T flying from the transport substrates 30 and 30 of the toner flying device 31 and being in a cloud state by the AC electric field is applied between the DC bias electric field. Will be contained. Therefore, scattering of the toner is prevented, and the image quality is further improved.

Next, an eighth embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 3 is an explanatory view of a main part of a developing device portion of the image forming apparatus.
In this embodiment, a toner flying device 31 having a concave storage portion 70 for accumulating toner on the supply side of the transfer substrates 30 and 30 is provided, and the transfer device 30 shown in FIG. Drive circuit 71 that changes and applies drive waveforms Va, Vb, and Vc in such a change pattern.
And a drive circuit 72 for changing and applying the drive waveforms Va, Vb and Vc to the lower transfer board 30 in a change pattern opposite to that shown in FIG. 7 as shown in FIG.

With this configuration, the toner is conveyed from the upper transfer substrate 30 of the toner flying device 31 and flies toward the photosensitive drum 1 in the same manner as described above. Since the driving waveform of the reverse change pattern is applied, the toner is transported in the reverse direction (the direction from the flying side to the supply side). That is, the lower transfer substrate 30 is a reverse transfer substrate.

With this configuration, the toner supplied from the toner box section 32 of the developing device 6 is stored in the storage section 7.
0, 70, and the transfer substrates 30, 3
At 0, the toner can be transported and fly without interruption. That is, when the amount of toner used is large,
It is necessary to continuously transport and fly the toner,
At this time, if the toner supply to the transfer substrates 30 and 30 cannot be performed in time, a shortage of toner will occur. Therefore, by transporting and flying while accumulating the toner in the storage units 70 and 70, a continuously stable toner can be obtained. Transport and flight can be performed, and deterioration of image quality can be prevented.

In addition, the toner that recoils without adhering to the photosensitive drum 1 is transported to the supply side by the lower transport substrate 30 and returned to the storage unit 70, and is stored in the storage unit 70 of the lower transport substrate 30. The toner returned to 70 is again subjected to development while being transferred to the upper transfer substrate 30. As a result, the toner can be effectively used, and scattering of the recoil toner can be prevented, so that the image quality can be improved.

Next, a ninth embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 3 is an explanatory view of a main part of a developing device portion of the image forming apparatus.
In this embodiment, a drive circuit 71 for changing and applying the drive waveforms Va, Vb, and Vc to the transfer substrate 30 on the upper side of the toner flying device 31 in a change pattern as shown in FIG. A mode in which the drive waveforms Va, Vb, and Vc are changed and applied to the transfer substrate 30 in a change pattern as shown in FIG. And a driving circuit 73 having a mode in which Vb and Vc are changed and applied.

Then, a mode switching signal for switching the mode is given from a control unit (not shown) to the driving circuit 73. The mode switching signal is a signal for selecting a mode in which the drive waveforms Va, Vb, and Vc are changed and applied in a change pattern as shown in FIG. 18 when the image forming apparatus is on standby, for example.

With such a configuration, during recording for forming a normal image, the drive circuit 73 also applies the drive waveforms Va, Vb, Since Vc is changed and applied, the upper and lower transport substrates 30 and 30 transport the toner to the flying side and fly, and fly the toner with a transport amount twice that of one transport substrate 30 for development. Can be.

In the standby mode, the drive circuit 73 changes and applies the drive waveforms Va, Vb, and Vc to the lower transfer substrate 30 in a change pattern as shown in FIG. The transfer substrate 30 of the transfer substrate transports the toner in the reverse direction.
It is in a state of being circulated between 0 and 30, and does not fly. As described above, since the toner does not fly during standby or the like, the scattering of the toner is more reliably prevented, and the image quality can be improved.

By providing two transfer substrates as described above, one of the transfer substrates is used as a transfer substrate for flying the toner and also as a reverse transfer substrate for transferring the toner to the supply side. The configuration is simplified.

Next, the toner flying device 3 according to each of the above embodiments will be described.
Another example of the toner transport mode in FIG. 1 will be described with reference to FIG. When the transport surfaces of at least two transport substrates 30 and 30 are arranged to face each other as in the toner flying device 31 in each of the above-described embodiments, the drive voltage and the gap between the transport surfaces are set so that the two transport substrates are transported. Substrates 30, 30
When the driving waveforms applied to the respective electrodes 42 are synchronized, the electric field curtain 81 generated by the upper transfer substrate 30 and the electric field curtain 82 generated by the upper transfer substrate 30 are connected.

As described above, when the electric field curtains 81 and 82 are connected, the toner does not move, and the toner is layered in a portion where the electric field curtains 81 and 82 are not connected. Therefore, by moving these electric field curtains 81 and 82 in the flying direction with a required time constant while being connected, the toner is conveyed to the flying side in a layer state, and the toner is intermittently discharged. It can be transported in layers.

In this case, a larger amount of toner is supplied from the transfer board 30 and the amount of unused toner increases depending on the image. Therefore, the unused toner is collected by the toner gutter 38 and is transferred to the reverse transfer path member 39. The toner is sent backward to the supply side. Here, the structure of the reverse transport path member 39 will be briefly described. A plurality of electrodes 92 for generating a spatially traveling wave electric field are provided on a flexible substrate 91, covered with a transport surface forming member 93, and a surface coat layer 94 is formed on the surface. By using the flexible substrate 91, a transfer surface of any shape can be formed, and the transfer surface can be arranged along the toner gutter 38.

In each of the above embodiments, an example has been described in which the toner is accelerated and flies. However, the toner is ejected from one end of the transport substrate at a constant transport speed (this is also included in “flying”). It can also be configured. In this case,
A plurality of electrodes may be arranged at equal intervals, and the same drive waveform may be applied with a phase shift.

[0073]

As described above, according to the image forming apparatus of the present invention, the charged toner is transported by electrostatic force and flies from one end of the transport substrate, and the toner cloud of the flying toner is removed. Since toner is generated, a toner having a uniform charge amount can be transported with a simple configuration to generate a toner cloud, toner scattering is reduced, and image quality is improved.

Here, by providing a pair of opposing transfer substrates and a means for generating an AC electric field between the electrodes at one end of the opposing transfer substrates, the toner can fly from the transfer substrate while securing the toner amount. It is possible to generate a toner cloud by the used toner. Further, the provision of the pair of opposed transfer substrates and the intermediate transfer substrate facing each of the pair of opposed transfer substrates makes it possible to transfer a larger amount of toner.

Further, by having a reverse transport substrate for transporting the toner toward the other end by electrostatic force along the transport surface opposite to the transport substrate, it is possible to collect unused toner with a simple configuration, Scattering can be prevented and toner can be easily reused. Further, by providing a toner gutter for collecting toner not used for development, toner scattering can be more reliably prevented. Since the toner gutter has a reverse conveyance member for conveying the collected toner in the reverse direction, the collected toner can be easily reused.

Further, by providing a means for generating a DC electric field between the electrode of the transfer substrate and the latent image carrier, the toner cloud can be vibrated, and more efficient development can be performed. it can. In addition, by providing a means for generating a DC electric field between the electrode provided on the outer surface side of the transfer substrate and the latent image carrier, toner can be sealed between the DC electric fields and toner scattering can be more reliably prevented. As a result, the area of the toner cloud is widened and the area of contact with the latent image carrier is increased, so that good high-density development without toner loss can be performed.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating an example of a developing device of the image forming apparatus.

FIG. 3 is a schematic cross-sectional explanatory view of a transfer board of a toner flying device in the developing device.

FIG. 4 is an explanatory plan view of the transfer substrate.

FIG. 5 is an explanatory diagram for explaining the operation of the toner flying device.

FIG. 6 is an explanatory diagram for explaining the principle of toner transfer by the transfer substrate;

FIG. 7 is an explanatory diagram illustrating an example of a change pattern of a drive waveform applied to the transfer substrate.

FIG. 8 is an explanatory diagram illustrating another example of a change pattern of a drive waveform applied to the transfer substrate.

FIG. 9 is an explanatory diagram for explaining the principle of a developing operation in the image forming apparatus.

FIG. 10 is an explanatory diagram for explaining a toner collecting operation in the image forming apparatus.

FIG. 11 is an explanatory view of a main part of a developing device part of an image forming apparatus according to a second embodiment of the present invention.

FIG. 12 is an explanatory view of a main part of a developing device part of an image forming apparatus according to a third embodiment of the present invention.

FIG. 13 is an explanatory view of a main part of a developing device part of an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 14 is an explanatory view of a main part of a developing device part of an image forming apparatus according to a fifth embodiment of the present invention.

FIG. 15 is an explanatory view of a main part of a developing device part of an image forming apparatus according to a sixth embodiment of the present invention.

FIG. 16 is an explanatory view of a main part of a developing device part of an image forming apparatus according to a seventh embodiment of the present invention.

FIG. 17 is an explanatory view of a main part of a developing device part of an image forming apparatus according to an eighth embodiment of the present invention.

FIG. 18 is an explanatory diagram for explaining a drive waveform pattern of reverse conveyance for explaining the embodiment;

FIG. 19 is an explanatory view of a main part of a developing device portion for explaining another example of the embodiment.

FIG. 20 is an explanatory view of a main part of a developing device used for describing another example of a toner conveyance mode.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum (latent image carrier), 5 and 8 ... Scanning optical system, 13 ... Polygon mirror, 15 ... Charging device, 16 ... Developing device, 17A, 17B ... Feeding unit, 20 ... Transfer charger, 21 ... Separation charger, 23: fixing roller pair, 3
0, 30A: transfer board, 30B: intermediate transfer board, 33:
Transport path member, 38: toner gutter, 39: reverse transport path member, 31: toner flying device, 41: support substrate, 42: electrode, 43: transport path forming member, 44: surface coat layer, 52
... AC power supply, 60 DC power supply, 70 storage unit.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Minoru Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Kiyoshi Tarumi 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Katsuo Sakai 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H077 AA12 AA15 AA37 AB04 AC13 AC16 AD00 AD36 AE02 EA20

Claims (8)

[Claims] 1. An image forming apparatus for supplying toner onto a latent image carrier and developing a latent image on the latent image carrier to form an image, wherein the charged toner is subjected to electrostatic force along a conveying surface. A transport substrate that has a plurality of electrodes for generating a spatial traveling wave electric field for transporting toward the one end side, and that transports the toner from the one end side toward the latent image carrier; and a transport substrate. Means for generating a toner cloud by toner flying from one end of the image forming apparatus. 2. The image forming apparatus according to claim 1, further comprising a pair of opposed transfer substrates, and means for generating an AC electric field between the electrodes at one end of the opposed transfer substrates. Characteristic image forming apparatus. 3. The image forming apparatus according to claim 1, further comprising: a pair of opposed transfer substrates; and an intermediate transfer substrate opposed to each of the pair of opposed transfer substrates. Forming equipment. 4. The image forming apparatus according to claim 1, further comprising: a reverse transport substrate that transports the toner toward the other end by electrostatic force along the transport surface in opposition to the transport substrate. An image forming apparatus comprising: 5. The image forming apparatus according to claim 1, further comprising a toner gutter for collecting toner not used for development. 6. The image forming apparatus according to claim 5, further comprising a reverse transport member that transports the toner collected in the toner gutter in a reverse direction. 7. The image forming apparatus according to claim 1, further comprising: means for generating a DC electric field between an electrode of the transfer substrate and the latent image carrier. Image forming apparatus. 8. The image forming apparatus according to claim 1, further comprising: a unit configured to generate a DC electric field between an electrode provided on an outer surface of the transfer substrate and the latent image carrier. An image forming apparatus.