JP2003098820A - Electrostatic transfer device and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of powder being unable to be carried by a low voltage drive. SOLUTION: Two adjacent electrodes 52 and 52 of a carrying board 31 are superposed partially in a carrying direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic transport device and an image forming apparatus.

[0002]

2. Description of the Related Art As an image forming apparatus such as a copying machine, a printer or a facsimile, an electrophotographic process is used to form a latent image on a latent image carrier and a developer (hereinafter referred to as "toner") is formed on the latent image. There is one in which an image is formed by adhering and developing the toner image to form a visible image, and transferring the toner image to a recording medium (including an intermediate transfer member).

In such an image forming apparatus, as a developing device for developing a latent image, conventionally, toner agitated in the developing device is carried on the surface of a developing roller, which is a developer carrying member, and the developing roller is rotated. The latent image bearing member is conveyed to a position facing the surface of the latent image bearing member by developing the latent image bearing member, and the latent image bearing member is developed. It is known that the toner is collected in the toner, the toner is newly stirred and charged, and the toner is carried again on the developing roller.

A developing device is disclosed in Japanese Patent Laid-Open No. 9-19.
As described in Japanese Patent No. 7781 and Japanese Patent Application Laid-Open No. 9-329947, there is also known a method of developing by a so-called jumping developing method in which toner is transferred from a developing roller to a latent image carrier in a non-contact manner.

Further, as a developing device, Japanese Patent Laid-Open No. 5-1
As described in Japanese Patent No. 9615, the electrostatic latent force is used to convey toner on the surface of the developing roller, and the toner is separated from the surface of the developing roller by the attraction force generated between the toner and the latent image carrier to carry the latent image. The toner is made to adhere to the body surface, or, as described in JP-A-59-181375, the toner is opposed to the latent image carrier by using a carrier substrate that conveys the toner by electrostatic force. There is also one in which the toner is conveyed to a position, and the toner is separated from the conveying surface by the suction force generated between the toner and the latent image carrier and attached to the surface of the latent image carrier.

Another image forming apparatus is disclosed in Japanese Patent Laid-Open No.
As described in JP-A-1-170591, JP-A-11-115235, and JP-A-11-179951, a control electrode is provided between a developing roller carrying toner and a recording medium. By arranging the back electrodes on the back side and generating an electric field between the back electrodes and the developing roller, the toner can fly toward the recording medium, and the flying of the toner is selectively controlled by the control electrode. A so-called flying type (toner jet type) image forming apparatus that forms an image on a recording medium is also known.

Further, as a powder carrying device for carrying powder such as toner, there is a device for carrying using a spatial traveling wave electric field as described in Japanese Patent Application Laid-Open No. 7-267363. This is because when a driving voltage is applied to the electrode, a spatial traveling wave electric field is formed around the electrode, and repulsive force and driving force act on the powder charged by the traveling wave electric field,
The powder is conveyed in the electric field traveling direction. As a classifying device for classifying powder such as toner using this space traveling wave electric field, as described in, for example, Japanese Patent Application Laid-Open No. 8-149859, classification is performed by applying electrostatic force, gravity, centrifugal force, and the like. It has been proposed to perform (separation).

[0008]

However, an image forming apparatus provided with a developing device for applying a toner to a latent image carrier using the above-mentioned developing roller, or a developing roller carrying toner to cause an electric field from the developing roller. In a flying-type image forming apparatus in which toner is controlled to fly to a recording medium, the toner enters between the developing roller and the developing device side plate, and the toner is rubbed to cause toner sticking, which adversely affects the image. When the developer or the toner is agitated and charged in the developing device, the toner may be scattered to cause the background stain of the image.

Further, when the toner is charged by frictional charging or corona discharge charging, saturated charged toner and unsaturated charged toner are mixed and a large charge distribution is obtained. When such toner is forcibly transferred to the developing roller by using a magnetic brush or a transfer roller, the developer once held on the developing roller at the developing speed of the developing roller (linear speed of about 100 cm / sec). Of these, the toner having a small charge is released, and the toner is likely to scatter and the formed image is liable to cause background stain.

Further, in a developing device which performs so-called jumping development, it is necessary to transfer charged toner by a high voltage, so a high voltage power source is required, which leads to an increase in size and cost of the device. There are challenges.

On the other hand, when the inventors of the present invention have researched an electrostatic transport device for transporting toner by using the electrostatic force of the conventional space traveling wave electric field, the width of the plurality of electrodes is 150 to 25.
In the conventional electrostatic transport device in which the distance between the electrodes is 0 μm and the distance between the electrodes is 250 to 500 μm, even if the toner is actually transported, the toner stays in a mountain shape between the electrodes and the stable toner transport is efficiently performed. I confirmed that I could not do it.

Further, when the toner is conveyed by electrostatic force, since the toner has a difference in size and shape, it is difficult to obtain stable conveyance by the conventional electrostatic conveying device also in this respect, and the toner and the charging member are aligned with each other. There are issues such as those that need to be addressed.

The present invention has been made in view of the above points, and provides an electrostatic transfer device capable of stably and efficiently transferring powder by driving at a low voltage, and the electrostatic transfer device is also provided. An object of the present invention is to provide an image forming apparatus using the TPM (Toner-Phase-Match) electrostatic transport technology used, which has a simple structure, can be manufactured at low cost, can be driven at a low voltage, and can obtain high image quality. To do.

[0014]

In order to solve the above-mentioned problems, an electrostatic carrying device according to the present invention has a plurality of electrodes for generating an electric field for moving powder by electrostatic force along a carrying surface. A carrier board having two adjacent two of the carrier boards.
The two electrodes are configured so that there is no gap in the transport direction. In the present specification, “powder” means “particle”, “fine particle”, “powder”, “fine powder”, “powder”,
It is used to mean "fine powder".

The electrostatic transfer device according to the present invention comprises a transfer substrate having a plurality of electrodes for generating an electric field for moving powder by electrostatic force along the transfer surface, and two adjacent transfer substrates are provided. The electrodes are configured so as to partially overlap in the transport direction. In this case, it is preferable that two adjacent electrodes overlap each other in the range of 1/10 or less of the electrode width in the transport direction.

In the electrostatic carrying device according to the present invention, there is a step between at least a part of two adjacent electrodes, and the range is 1/3 to 10 times the particle diameter of the powder carried on the carrying surface. The uneven portion is preferably formed, and the width of the electrode is preferably within the range of 1/3 to 5 times the particle diameter of the powder to be conveyed.

The image forming apparatus according to the present invention includes the electrostatic transport device according to the present invention for transporting charged toner by electrostatic force.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an embodiment of an image forming apparatus according to the present invention will be described with reference to FIG. It should be noted that this figure is an overall schematic configuration diagram of the image forming apparatus. The overall outline and operation of this image forming apparatus will be described. A photosensitive drum 1 (for example, an organic photosensitive member: a latent image carrier) is described.
The OPC) is rotationally driven clockwise in the figure. When a document is placed on the contact glass 2 and a print start switch (not shown) is pressed, a scanning optical system 5 including a document illumination light source 3 and a mirror 4, and a scanning optical system 8 including mirrors 6 and 7 are provided.
And move to read the original image.

Here, the scanned original image is read as an image signal by the image reading element 10 arranged behind the lens 9, and the read image signal is digitized and image-processed. Then, the laser diode (LD) is driven by this image-processed signal, the laser light from this laser diode is reflected by the polygon mirror 13, and then is irradiated onto the photosensitive drum 1 via the 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 photosensitive drum 1 is a developing device 16 equipped with the electrostatic transport device according to the present invention.
The toner adheres to form a visible image by the toner, and the visible image is fed from the paper feeding unit 17A or 17B to the paper feeding roller 18A or 1A.
It is transferred to the transfer paper (recording medium) 19 fed by 8B by corona discharge of the transfer charger 20. The transfer paper 19 on which the visible image is 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,
The visible image is fixed and discharged to the discharge tray 24 outside the machine.

On the other hand, the toner remaining on the surface of the photosensitive drum 1 which has been transferred is removed by the cleaning device 25, and the electric charge remaining on the surface of the photosensitive drum 1 is erased by the discharging lamp 26.

Next, a first embodiment of the developing device 16 equipped with the fine powder conveying device according to the present invention in this image forming apparatus will be described with reference to FIGS. 2 is an explanatory view of a developing device portion of the image forming apparatus, FIG. 3 is a cross-sectional explanatory view of a carrying substrate of the developing device, FIG. 4 is an enlarged explanatory view of a carrying area of the carrying substrate, and FIG. It is an expanded explanatory view of the pumping area | region of a board | substrate.

The developing device 16 conveys charged toner to one end side by electrostatic force along the conveyance surface, and conveys substrate 31 for pumping toner near the photosensitive drum 1 by electrostatic force, and the conveyance substrate 31. A flexible carrying substrate 33 for feeding the toner charged on the substrate 31 from the toner box portion 32, a charging roller 34 for charging the toner to be supplied to the toner box portion 32, and a charging blade 35 arranged in contact with the peripheral surface of the charging roller 34. And a toner supply screw 3 for stirring the toner in the toner supply unit 36.
7 and a toner collecting section 38 for collecting the toner that has come off one end of the carrying substrate 31 and returning it to the toner box section 32.

The image forming apparatus is provided with a drive circuit 41 for applying a drive waveform (about 5 to 100 V) for toner transport and toner pumping to the electrode of the transport substrate 31 of the developing device 16. Further, a DC power source 43 for applying a DC bias (about 100 to 200 V), which is a developing bias voltage, is provided between the photosensitive drum 1 and the transport substrate 31.

As shown in FIGS. 3 to 5, the carrier substrate 31 has a large number of electrodes 5 having a required shape on a supporting substrate 51 having a width substantially the same as the drum 1 in the axial direction of the photosensitive drum 1.
2, 52, 52 ... Are arranged along the transport direction at a predetermined interval in the direction orthogonal to the transport direction, and an insulative protective film 53 forming a transport surface is laminated thereon, and the insulative protective film is formed. 5
3 has a large number of electrodes 52, 52, 5 having a desired shape.
2 ... Are arranged at a required interval in the direction orthogonal to the transport direction along the transport direction, and an insulating protective film 54 forming a transport surface is laminated thereon, and on the surface of the insulating protective film 54. A surface coating layer (not shown) that reduces the contact resistance with the toner is formed.

Here, as the supporting substrate 51, 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. What was done can be used. The electrode 52 is formed using a conductive material such as Al, Ni-Cr, and Cu.

As the insulating protective films 53 and 54, for example,
SiO_Two, SiON, TiN, Ta _TwoO₅Thickness 1
It is formed by forming a film with a thickness of up to 2 μm. As this protective film 53
By using a material with a large relative permittivity,
The pressure can be lowered and the particles (toner)
-) Drive recoil and transport speed increase. The transport surface
Surface coating layer formed on (surface of insulating protective film 54)
Is a machine that reduces the contact resistance between the transport surface and the charged toner interface.
It is a functional film, for example PTFE, PFA, etc.
Formed by coating a fluorine-based resin material to a thickness of 0.1 to 0.3 μm
Is made.

The flexible transport substrate 33 has the same basic structure as the transport substrate 31, but a large number of electrodes are arranged at a required interval on an insulating FPC substrate which also serves as a support substrate and a protective film, and the FPC is used. The surface coat layer is formed on the transfer surface side of the substrate.

Here, the arrangement of electrodes on the carrier substrate 31 will be described. First, the transport area 31 for transporting mainly
In the T portion, as shown in an enlarged view in FIG.
By arranging the two electrodes 52, 52 up and down with the insulating protective film 53 interposed therebetween, the two adjacent electrodes 52, 52 are partially overlapped in the transport direction. The two adjacent electrodes 52, 52 have a distance t of zero (t
It is also possible to set it as = 0).

Therefore, in the transfer area 31T of the transfer substrate 31, the overlapping range t of the two adjacent electrodes 52 in the transfer direction is t = 0 when the width of the electrode 52 is G. , 1/10 or less of the electrode width G (0 ≦ t ≦ G * 1/10). Also, the electrode width G
Is 1 of the particle diameter r of the toner T, which is the particle diameter of the powder to be conveyed.
Within the range of / 3 to 5 times (r * 1/3 ≦ r ≦ 5 * r).

In the transport / pumping region 31P for transport and pumping, as shown in an enlarged view in FIG. 5, first, two adjacent electrodes 52, 52 are vertically arranged with an insulating protective film 53 interposed therebetween. By arranging, the two adjacent electrodes 52, 52 are arranged so as to partially overlap in the transport direction. It should be noted that the two adjacent electrodes 52, 52 may be arranged with the interval t set to zero (t = 0) in the carrying direction.

Therefore, in the transfer / pumping region 31P of the transfer substrate 31, two adjacent electrodes 5 are provided.
When the width of the electrode 52 is G, the overlapping range t of 2, 52 in the transport direction is 1/10 or less of the electrode width G including t = 0 (0 ≦ t ≦ G * 1/10). ). Also,
The electrode width G is in the range of 1/3 to 5 times the particle diameter r of the toner T to be conveyed, which is the particle diameter of the powder to be conveyed (r * 1/3 ≦ r.
≦ 5 * r).

Then, two electrodes 52, 5 which are further adjacent to each other
A step is provided between the two, and due to this step, 1/3 to 10 of the particle diameter r of the toner T, which is the particle diameter of the powder to be conveyed, is conveyed to the conveying surface.
The unevenness having the depth D within the double range (r * 1/3 ≦ D ≦ 10 * r) is formed.

Here, as the transfer substrate 31, as described above, the transfer region 31T for mainly carrying and the transfer / pumping region 31P for carrying and pumping are set as one.
Although it is composed of a single substrate, it is also possible to use separate substrates for each, and a developing device for ejecting and ejecting toner from the end portion of the transport substrate 31 using the transport substrate corresponding to the transport region 31T. Can also be configured.

The driving circuit (driving power source) 41 is provided on the carrier substrate 3.
A set of three electrodes 52, 52, 52 of 1 is provided as a set, and a pulsed driving voltage (driving waveform) Va of a multi-phase (three phases here, but six phases can be used) is set for each electrode 52. ,
Vb and Vc are applied respectively.

Next, the conveyance and pumping of toner by electrostatic force by the conveyance substrate 31 of the developing device 16 in the image forming apparatus having the above-mentioned structure will be described with reference to FIGS. 6 to 8. First, as shown in FIG. 6, pulse-shaped drive waveforms Va, Vb, and Vc, which change between the ground G and the positive voltage +, are applied to the electrode 52 of the carrier substrate 31 at different timings. At this time, as shown in FIG. 7, there is the negatively charged toner T on the carrier substrate 31, and “G”, “G”, and “+” are respectively indicated by the plurality of continuous electrodes 52 of the carrier substrate 31. , “G”, and “G” are applied, the negatively charged toner T is located on the “+” electrode 52.

At the next timing, the plurality of electrodes 52 are respectively marked with "+", "G", "G", "+", as shown in.
Since “G” is applied, a repulsive force acts on the negatively charged toner T with the “G” electrode 52 on the left side in the drawing, and an attractive force acts with the “+” electrode 52 on the right side, respectively. The negatively charged toner T moves to the “+” electrode 52 side. Further, “G”, “+”, “G”, “G”, and “+” are respectively applied to the plurality of electrodes 52 at the next timing as shown by, and the repulsive force is similarly applied to the negatively charged toner T. And the suction force act on the negatively charged toner T.
Move to side 2.

By thus changing the potential of the drive waveform applied to the electrode 52 and apparently moving the drive waveform, the negatively charged toner T moves while being pulled toward the "+" electrode 52 side, and therefore the carrier is conveyed. The negatively charged toner T is transported along the transport surface of the substrate 31. In the case of positively charged toner, it can be conveyed by reversing the change pattern of the drive waveform.

Here, in the transfer region 31T of the transfer substrate 31, the drive electrodes 52 are very close to each other or the drive electrodes 52 are superposed, so that the drive electric field is close to the electrodes 52, 52. Place (between insulating protective films)
(Depending on the dielectric constant), the toner T is greatly subjected to the driving electric field. Therefore, the toner T does not fly due to a large jump on the surface of the substrate 31, and is transported by the moving electric field by the drive electrode 52 along the surface of the substrate 31, and the transported toner T is a high-speed transport dependent on the match-following drive frequency. Thus, low voltage driving (about 10 to 50 V) becomes possible.

On the other hand, in the transfer / pumping region 31P of the transfer substrate 31, the drive electrodes 52 are very close to each other, or the drive electrodes 52 overlap each other, and unevenness due to a step is formed on the transfer surface. Since the toner T is formed, the toner T repeatedly falls and jumps to the step (concave portion) during the transportation, and the toner T is transported along the surface of the substrate 31 while making a large jump on the surface of the substrate 31.

That is, the pumping phenomenon can be achieved by controlling the surface shape of the carrier substrate 31 regardless of the period of the drive waveform, the magnitude of the pulse, and the sign. In addition, the size of the depression (recessed portion) is set to be several times the size of the carried particles,
The flight increases according to the size. This allows pumping control and transport.

Therefore, in this image forming apparatus, by applying the drive waveform from the drive circuit 41, the toner T is transferred at high speed in the transfer area of the transfer substrate 31 along the transfer surface of the transfer substrate 31 onto the photosensitive drum 1. When the toner T is transported to the vicinity, and the toner T is transported near the photosensitive drum 1, pumping occurs.

In this case, among the toners T to be pumped, as shown in FIG. 8, there is also the toner T which recoils backward with respect to the traveling direction of the toner T, but as a whole, it slowly moves in the traveling direction (conveying direction). Be transferred. At this time, by applying a DC bias from the power source 43 between the photosensitive drum 1 and the electrode 58 provided on the back surface of the transport substrate 31, the toner being pumped is accelerated and flies.

As the toner is pumped in the vicinity of the photosensitive drum 1 in this way, the toner is attracted and fixed to the latent image portion formed on the photosensitive drum 1 by a strong Coulomb force, but in the non-latent image portion. Since the cloning force is weak, or the toner is not repelled due to repulsion due to positive and negative charging, the toner is not fixed and fixed, so that a static image can be developed by the toner. Then, since the toner is pumped and collides with the photoconductor drum 1, unnecessary toner that may adhere to the non-latent image portion, and toner having multiple adhesion to the latent image portion have a weak adsorption force on the surface layer. Since the toner is peeled off and removed (this effect is called the scavenger effect), it becomes possible to obtain an image having a large sharpness.

In this case, 30 to 200 V is sufficient as the bias voltage applied to the photosensitive drum 1 in order to pump larger toner, as described above,
Low voltage can be achieved. That is, in the conventional so-called jumping developing system, in order to separate the charged toner from the developing roller and transfer it to the photoconductor, an applied voltage higher than the adhesive force of the toner to the developing roller is required.
A bias voltage of ~ 900V must be applied. On the other hand, according to the present invention, the adhesion force of the toner is usually 5
Although it is 0 to 200 nN, since the adhesive force to the transport substrate 31 becomes substantially zero because of pumping, the force for peeling the toner from the transport substrate 31 becomes unnecessary, and 30 to 20 nN
Even with a bias voltage of 0 V, the toner can be sufficiently transferred to the photoconductor.

Thus, the TPM (Toner-Phase-Mat)
ch) By using electrostatic transport technology, by providing a pumping generation means for pumping toner by electrostatic force in the vicinity of the latent image carrier, non-contact transport and development can be performed,
No toner friction, crushing, scattering, roller filming, etc. by the developing roller, simple structure, low cost, low voltage, sharp and high image quality can be obtained. Become.

Further, by electrostatically transporting the toner using the transport substrate 31, by configuring the transport substrate 31 between the electrodes and the electrode size suitable for the toner size, it is possible to control the micro transport of the toner. it can. Toner is q / m
Is −15 to 20 μc / g, 2 V per 1 μm
With the above electric field strength, it can be transported. Therefore, the drive potential of the drive waveform is 5V to 50V, although it depends on the electrode configuration of the carrier substrate 31.

As a result, by performing electrostatic development of toner and electrostatic pumping of toner, the toner transfer voltage 10 is applied to the portion related to the developing device of the image forming apparatus.
Even if the DC bias voltage is 0 V, the developing voltage ± 200 V, and the DC bias voltage is low, it is possible to perform development with a large S / N ratio and further reduce the voltage of the entire apparatus. Also, due to electrostatic transport of toner, electric field (electric field strength), frequency, waveform,
Further, by controlling the permittivity and surface state of the material to be transferred, and also the interfacial force of the interface of the transfer substrate and the critical Eg, transfer and pumping can be obtained as a phenomenon. ) Is also extremely small.

Further, as described above, when the toner is pumped by changing the frequency of the drive waveform applied to the transfer substrate (increasing the drive frequency of the developing portion), the electrode pattern of the transfer substrate is transferred. The same can be applied to the section and the pumping generation section, which simplifies the structure of the transfer board.

Next, another example of the carrier substrate will be described with reference to FIG. 9 and subsequent figures. First, the transport substrate 71 corresponding to the transport region 31T will be described with reference to FIG. 9. In the transport substrate 71, when two adjacent electrodes 52, 52 are partially overlapped or the interval is zero, The electrode 52 is overlapped with the adjacent one end side electrode 52 within zero or within 1/10 of the electrode width G, and is separated from the one end side electrode 52 by a distance R. . The interval R is 10 times or less the particle diameter r of the particles to be conveyed (R ≦ r *
10), and preferably within the range of 2 times to 10 times the particle diameter r (r * 1/2 ≦ R ≦ r * 10).

In this carrier substrate 71, when the drive waveform is applied, the electric field as shown in FIG. 10 is obtained by adjusting the electrode ends from overlapping to having a gap in the particle traveling direction of the phase shift drive waveform (voltage pulse). Is generated, the carrier particles are matched and followed by the driving electrode 52, and flying occurs on the end surface side where the electrodes are open, which enables higher speed and lower voltage.

Next, the transport substrate 81 corresponding to the transport / pumping region 31P will be described with reference to FIG. 11. The transport substrate 81 is formed by etching the support substrate 51 itself to form the recess 51a. By providing the support substrate 51 with the electrodes 53 and the protective films 53 and 54, irregularities are formed on the transport surface. In this case, a step is formed between the two adjacent electrodes 52, 52 as described above. Thus, by providing the support substrate 51 itself with the irregularities, the process is easy and the cost can be reduced.

Next, another embodiment of the image forming apparatus according to the present invention will be described with reference to FIGS.
Note that FIG. 12 is a schematic explanatory view of the image forming apparatus, and FIGS. 13 and 14 are explanatory views showing different examples of aperture members of the image forming apparatus.

This image forming apparatus has the above-mentioned carrying substrate 31 having a carrying area for carrying the toner supplied from the toner supplying section 90 and a carrying and pumping area.
And a drive circuit 92 for applying a drive waveform to the electrode 52 of the carrying substrate 31, and an intermediate electrode arranged between the recording medium 93 to be carried and the carrying substrate 31 for controlling passage / blocking of toner. An aperture member 94 and a drive circuit 95 for controlling the aperture member 94 are provided.

The recording medium 93 is, for example, the feed roller 10.
It is conveyed by being electrostatically adsorbed on the conveyor belt 103 stretched between the first and the second 102. The back electrode 104 is arranged on the back side of the transport belt 103 at a position facing the transport substrate 91,
A DC power supply 105 is provided between the carrier substrate 91 and the back electrode 104.
The DC bias voltage is applied from.

In the aperture member 94, as shown in FIG. 13, for example, a large number of through holes 97 through which toner can pass are formed in a row on a substrate 96 such as polyimide or ceramics, and an intermediate electrode (around each through hole 97). Aperture electrode) 98 is formed. Also, for example, as shown in FIG.
A large number of through holes 97 through which the toner can pass can be formed in a zigzag pattern. The size and pitch of the through holes 98 of the aperture member 94 are determined according to the target pixel density (dpi). The drive circuit 95 turns on / off the voltage applied to each of the intermediate electrodes 98, 98 of the aperture member 94 in accordance with the image signal, thereby opening / closing the through hole 87 (toner passage / interruption) in accordance with the image signal. .

In the image forming apparatus thus constructed, the toner is pumped on the carrier substrate 31, and the pumped toner is the intermediate electrode 9 of the aperture member 94.
8 passes through the through hole 97 that is on (passing), and DC
Since the toner particles fly toward the recording medium 93 by the bias voltage and adhere to the recording medium 93, the toner adheres to the recording medium 93 according to the formed image. Therefore, an image can be formed by fixing the toner image.

In this case, since the toner is pumped on the transport substrate 31, the adhesive force to the transport substrate 31 becomes substantially zero as described above, so the toner is transported to the transport substrate 31.
The force of peeling off the toner becomes unnecessary, and the toner can be made to fly and adhere to the recording medium even with a bias voltage of 30 to 100V. That is, since the bias is applied and the toner is sucked from the state where the toner is separated from the substrate, the image force (Coulomb force) and the initial flying force of the toner peeling from the substrate are not required, and the low voltage bias makes it easy. Can be sucked into.

Direct printing and drawing can be performed based on a digital image signal without the need for a latent image carrier (photoreceptor), and the intermediate electrode (aperture electrode) is made to correspond to a pixel so that an arbitrary pixel is formed. The size and definition can be increased.

As described above, by pumping the toner by the electrostatic force, it is possible to obtain a so-called flying-type image forming apparatus having a small number of parts, a small power consumption, and a compact size. Here, although the pumped toner is directly flying-attached to the transfer paper, the toner image is once formed on the intermediate transfer member such as the intermediate transfer belt and is transferred from the intermediate transfer member to the transfer paper. You can also Such an intermediate transfer member is also included in the "recording medium".

In the above embodiment of the present invention,
An example in which the electrostatic transport device is applied to a developing device of an image forming apparatus according to the present invention has been described. However, since the magnitude of toner pumping depends on q / m (charge and mass) of the toner, a predetermined range of The present invention can be applied not only to a toner selecting device that selects only q / m toner, but also to a classifying device that classifies (selects) fine powder other than toner.

[0062]

As described above, according to the electrostatic transfer device of the present invention, the transfer substrate having the plurality of electrodes for generating the electric field for moving the powder by the electrostatic force along the transfer surface is provided. Since the two adjacent electrodes of the transfer substrate are configured to have no gap in the transfer direction, the powder can be stably and efficiently transferred at high speed by low voltage driving.

The electrostatic transfer device according to the present invention comprises a transfer substrate having a plurality of electrodes for generating an electric field for moving powder by electrostatic force along the transfer surface. Since the electrodes partially overlap in the carrying direction, the powder can be stably and efficiently carried at high speed by low voltage driving. In this case, two adjacent electrodes overlap each other in the range of 1/10 or less of the electrode width in the carrying direction, so that the powder can be carried at high speed by low voltage driving.

In the electrostatic carrying device according to the present invention, there is a step between at least a part of two adjacent electrodes, and the step is within a range of 1/3 to 10 times the particle diameter of the powder to be carried. As a result, the powder can be transported and pumped. Moreover, the width of the electrode is 1 / the particle size of the powder to be conveyed.
Within the range of 3 to 5 times, it becomes possible to carry and pump.

According to the image forming apparatus of the present invention, since the electrostatic carrying device of the present invention for carrying the charged toner by the electrostatic force is provided, the toner can be carried and / or pumped by the low voltage driving. It is possible to obtain high image quality.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of a developing device portion of the image forming apparatus.

FIG. 3 is an explanatory cross-sectional view of a carrier substrate of the developing device.

FIG. 4 is an enlarged explanatory view of a main part of the carrier substrate

FIG. 5 is an enlarged explanatory view of a main part of another portion of the transport board.

FIG. 6 is an explanatory diagram for explaining a drive waveform output from a drive circuit of the developing device.

FIG. 7 is an explanatory diagram for explaining the principle of toner transport by the transport substrate.

FIG. 8 is an explanatory diagram for explaining the operation of toner pumping in the image forming apparatus.

FIG. 9 is a cross-sectional explanatory view illustrating another example of the transfer substrate of the electrostatic transfer device according to the present invention.

FIG. 10 is an explanatory sectional view for explaining the operation of the carrier substrate.

FIG. 11 is a cross-sectional explanatory diagram illustrating still another example of the transfer substrate of the electrostatic transfer device according to the present invention.

FIG. 12 is a schematic explanatory diagram of another embodiment of the image forming apparatus according to the present invention.

FIG. 13 is an explanatory top view showing an example of an aperture member of the image forming apparatus.

FIG. 14 is a perspective explanatory view showing another example of the aperture member of the image forming apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum (latent image carrier), 5, 8 ... Scanning optical system, 13 ... Polygon mirror, 15 ... Charging device, 16 ... Developing device, 17A, 17B ... Paper feeding part, 20 ... Transfer charger, 21 ... Separation Charger, 23 ... Fixing roller pair, 3
1, 71, 91 ... Transport board, 33 ... Transport path member, 38 ...
Toner collecting unit, 41 ... Driving circuit, 51 ... Support substrate, 52
... electrodes, 53, 54 ... insulating protective film, 55 ... surface coating layer.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nobuaki Kondo             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Makoto Ou             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F term (reference) 2H029 DB00                 2H077 AB02 AC04 AC13 AD01 AD04                       AD11 AD13 AD14 AD16 AE03                       AE04 EA14 EA16 EA20 FA00                 3F021 AA01 BA05 CA13

Claims (6)

[Claims] 1. An electrostatic transport device for transporting powder by electrostatic force, comprising a transport substrate having a plurality of electrodes for generating an electric field for moving the powder along the transport surface by electrostatic force. An electrostatic transfer device, wherein two adjacent electrodes on the transfer substrate have no gap in the transfer direction. 2. An electrostatic transfer device for transferring powder by electrostatic force, comprising a transfer substrate having a plurality of electrodes for generating an electric field for moving the powder along the transfer surface by electrostatic force. An electrostatic transfer device in which two adjacent electrodes on the transfer substrate partially overlap in the transfer direction. 3. The electrostatic carrier device according to claim 2, wherein the two adjacent electrodes are 1 / the electrode width in the carrying direction.
An electrostatic transfer device characterized by overlapping in a range of 10 or less. 4. The electrostatic carrying device according to claim 1, wherein there is a step between at least a part of the adjacent two electrodes, and the particle size of the powder to be carried on the carrying surface is 1 An electrostatic transfer device, wherein irregularities within a range of ⅓ to 10 times are formed. 5. The electrostatic carrying device according to claim 1, wherein the width of the electrode is within a range of 1/3 to 5 times the particle diameter of the powder to be carried. Electrostatic transfer device. 6. An image forming apparatus for forming an image using charged toner, comprising the electrostatic carrying device according to claim 1 for carrying the toner by electrostatic force. Image forming apparatus.