# US 6,947,691 B2 · Electrostatic transportation device, development device and image formation apparatus

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- Number: US 6,947,691 B2
- Document ID: US6947691B2
- Status: Granted
- Kind: B2
- Application number: 10/751,453
- Filed: 2004-01-06
- Published: 2004-08-12
- Granted: 2005-09-20
- Earliest claimed: 2001-03-15
- Assignees: Ricoh Company, Ltd.
- Inventors: Yohichiro Miyaguchi; Nobuaki Kondoh; Takeshi Takemoto; Katsuo Sakai; Masanori Horike
- Web page: https://patentgrep.com/patent/US6947691B2

## CPC

- G03G 15/08: using a solid developer, e.g. powder developer
- G03G 15/0822: {Arrangements for preparing, mixing, supplying or dispensing developer}
- G03G 2215/0646: Electrodes only acting from one side of the developing area, e.g. plate electrode
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

An electrostatic transportation device is provided with a transporting base plate having a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force, wherein a width of each of the electrodes in a travelling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the travelling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, and driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes.

## Claims

### Claim 1

A development device comprising:
An electrostatic transportation device which moves fine particles by an electrostatic force, said electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, the transporting base plate has an inorganic or organic surface protective layer covering the electrodes, and the thickness of the surface protective layer does not exceed 10 μm; the surface protective layer comprises a single layer or a plurality of layers, at least the outermost layer of the surface protective layer provided on the transporting base plate is formed from a material positioned in the vicinity of a material used as a charge controlling agent of fine particles on a frictional charge sequence or a material positioned on a positive end side, and fine particles with a negatively charged polarity are moved.

### Claim 2 (depends on 1)

The developmental device of claim 1, wherein the thickness of the electrodes does not exceed 3 μm.

### Claim 3

A development device comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, the transporting base plate has an inorganic or organic surface protective layer covering the electrodes, and the thickness of the surface protective layer does not exceed 10 μm; the surface protective layer comprises a single layer or a plurality of layers, at least the outermost layer of the surface protective layer provided on the transporting base plate is formed from a material positioned in the vicinity of a material used as a charge controlling agent of fine particles on a frictional charge sequence or a material positioned on a negative end side, and fine particles with a positively charged polarity are moved.

### Claim 4

A development device comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, the transporting base plate has an inorganic or organic surface protective layer covering the electrodes, and the thickness of the surface protective layer does not exceed 10 μm; and the outermost surface of the surface protective layer is coarsened.

### Claim 5

A development device comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, and pulse-like driving waveforms of n phases (n is an integer of 3 or more) or more are applied and a voltage application time per one phase is less than cycle period time ×(n−1)/n.

### Claim 6 (depends on 5)

The development device according to claim 5, wherein a base member serving as the transporting base plate is formed from a flexibly deformable material.

### Claim 7 (depends on 5)

The development device according to claim 5, wherein the electrostatic transportation device further comprises a unit which vibrates the transporting base plate intermittently or continuously.

### Claim 8

A development device comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, pulse-like driving waveforms of n phases (n is an integer of 3 or more) or more are applied, and a time period when a voltage which repels fine particles is applied to an electrode of a observed phase and a time period when a voltage which repels fine particles is applied to an upstream side electrode adjacent thereto and simultaneously a voltage which attracts fine particles is applied to a downstream side electrode adjacent thereto are set to 30 μsec or more.

### Claim 9

A development device comprising:
a photosensitive body, and
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body,
wherein a charge potential of the surface of the photosensitive body is |200|V or less.

### Claim 10 (depends on 9)

The development device according to claim 9, wherein the transporting base plate has an inorganic or organic surface protective layer covering the electrodes, and the thickness of the surface protective layer does not exceed 10 μm.

### Claim 11 (depends on 10)

The development device according to claim 10, wherein the thickness of the electrodes does not exceed 3 μm.

### Claim 12 (depends on 10)

The development device according to claim 10, wherein the surface protective layer comprises a single layer or a plurality of layers, at least the outermost layer of the surface protective layer provided on the transporting base plate is formed from a material positioned in the vicinity of a material used as a charge controlling agent of fine particles on a frictional charge sequence or a material positioned on a positive end side, and fine particles with a negatively charged polarity is moved.

### Claim 13 (depends on 10)

The development device according to claim 10, wherein the surface protective layer comprises a single layer or a plurality of layers, at least the outermost layer of the surface protective layer provided on the transporting base plate is formed from a material positioned in the vicinity of a material used as a charge controlling agent of fine particles on a frictional charge sequence or a material positioned on a negative end side, and fine particles with a positively charged polarity is moved.

### Claim 14 (depends on 10)

The development device according to claim 10, wherein the outermost surface of the surface protective layer is coarsened.

### Claim 15 (depends on 9)

The development device according to claim 9, wherein the transporting base plate is constituted by forming thin layer electrodes and a thin layer surface protective layer on a base member serving as a base sequentially in a stacking manner by an etching process, a deposition process or a combination of the etching process and the deposition process.

### Claim 16 (depends on 15)

The development device according to claim 15, wherein the thin layer electrodes are formed by etching or patterning after formed by a vapor deposition process or an electro-deposition process, and the protective layer is formed by a sputtering, coating, or spray coating.

### Claim 17 (depends on 9)

The development device according to claim 9, wherein a base member serving as the transporting base plate is formed from a flexibly deformable material.

### Claim 18 (depends on 9)

The development device according to claim 9, wherein pulse-like driving waveforms of n phases (n is an integer of 3 or more) or more is applied and a voltage application time per one phase is less than cycle period time×(n−1)/n.

### Claim 19 (depends on 9)

The development device according to claim 9, wherein pulse-like driving waveforms of n phases (n is an integer of 3 or more) or more is applied, and a time period when a voltage which repels fine particles is applied to an electrode of a observed phase and a time period when a voltage which repels fine particles is applied to an upstream side electrode adjacent thereto and simultaneously a voltage which attracts fine particles is applied to a downstream side electrode adjacent thereto are set to 30 μsec or more.

### Claim 20 (depends on 9)

The development device according to claim 9, further comprising a unit which vibrates the transporting base plate intermittently or continuously.

### Claim 21 (depends on 9)

The development device according to claim 9, wherein a vertical field intensity at a height position corresponding to the average diameter of each fine particle on the surface in the vicinity of the electrode center of the surface of the transporting base plate which performs hopping of the fine particles by an electrostatic force is 1×106 V/m or more.

### Claim 22 (depends on 9)

The development device according to claim 9, wherein a spacing between the latent image carrier and the surface of the transporting base plate which performs hopping of the fine particles by an electrostatic force is in a range of 2 to 10 times a hopping height of the fine particles.

### Claim 23 (depends on 9)

The development device according to claim 9, wherein a spacing between the latent image carrier and the surface of the transporting base plate which performs hopping of the fine particles by an electrostatic force is in a range of ½ to 2 times a hopping height of the fine particles.

### Claim 24 (depends on 9)

The development device according to claim 9, wherein driving waveforms where a driving frequency of each phase is in a range of 1 KHz to 15 KHz are applied to the electrodes of the transporting base plate which performs hopping of the fine particles by an electrostatic force.

### Claim 25

An image formation apparatus comprising:
a photosensitive body, and
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on the photosensitive body are set such that an electric field generated by the diving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body.
wherein a charge potential of the surface of the photosensitive body is |200|V or less.

### Claim 26 (depends on 25)

The image forming apparatus according to claim 25, wherein the transporting base plate has an inorganic or organic surface protective layer covering the electrodes, and the thickness of the surface protective layer does not exceed 10 μm.

### Claim 27 (depends on 26)

The image forming apparatus according to claim 26, wherein the thickness of the electrodes does not exceed 3 μm.

### Claim 28 (depends on 26)

The image forming apparatus according to claim 26, wherein the surface protective layer comprises a single layer or a plurality of layers, at least the outermost layer of the surface protective layer provided on the transporting base plate is formed from a material positioned in the vicinity of a material used as a charge controlling agent of fine particles on a frictional charge sequence or a material positioned on a positive end side, and fine particles with a negatively charged polarity is moved.

### Claim 29 (depends on 26)

The image forming apparatus according to claim 26, wherein the surface protective layer comprises a single layer or a plurality of layers, at least the outermost layer of the surface protective layer provided on the transporting base plate is formed from a material positioned in the vicinity of a material used as a charge controlling agent of fine particles on a frictional charge sequence or a material positioned on a negative end side, and fine particles with a positively charged polarity is moved.

### Claim 30 (depends on 26)

The image forming apparatus according to claim 26, wherein the outermost surface of the surface protective layer is coarsened.

### Claim 31 (depends on 25)

The image forming apparatus according to claim 25, wherein the transporting base plate is constituted by forming thin layer electrodes and a thin layer surface protective layer on a base member serving as a base sequentially in a stacking manner by an etching process, a deposition process or a combination of the etching process and the deposition process.

### Claim 32 (depends on 31)

The image forming apparatus according to claim 31, wherein the thin layer electrodes are formed by etching or patterning after formed by a vapor deposition process or an electro-deposition process, and the protective layer is formed by a sputtering, coating, or spray coating.

### Claim 33 (depends on 25)

The image forming apparatus according to claim 25, wherein a base member serving as the transporting base plate is formed from a flexibly deformable material.

### Claim 34 (depends on 25)

The image forming apparatus according to claim 25, wherein pulse-like driving waveforms of n phases (n is an integer of 3 or more) or more is applied and a voltage application time per one phase is less than cycle period time×(n−1)/n.

### Claim 35 (depends on 25)

The image forming apparatus according to claim 25, wherein pulse-like driving waveforms of n phases (n is an integer of 3 or more) or more is applied, and a time period when a voltage which repels fine particles is applied to an electrode of a observed phase and a time period when a voltage which repels fine particles is applied to an upstream side electrode adjacent thereto and simultaneously a voltage which attracts fine particles is applied to a downstream side electrode adjacent thereto are set to 30 μsec or more.

### Claim 36 (depends on 25)

The image forming apparatus according to claim 25, further comprising a unit which vibrates the transporting base plate intermittently or continuously.

### Claim 37 (depends on 25)

The image forming apparatus according to claim 25, wherein a vertical field intensity at a height position corresponding to the average diameter of each fine particle on the surface in the vicinity of the electrode center of the surface of the transporting base plate which performs hopping of the fine particles by an electrostatic force is 1×106 V/m or more.

### Claim 38 (depends on 25)

The image forming apparatus according to claim 25, wherein a spacing between the latent image carrier and the surface of the transporting base plate which performs hopping of the fine particles by an electrostatic force is in a range of 2 to 10 times a hopping height of the fine particles.

### Claim 39 (depends on 25)

The image forming apparatus according to claim 25, wherein a spacing between the latent image carrier and the surface of the transporting base plate which performs hopping of the fine particles by an electrostatic force is in a range of ½ to 2 times a hopping height of the fine particles.

### Claim 40 (depends on 25)

The image forming apparatus according to claim 25, wherein driving waveforms where a driving frequency of each phase is in a range of 1 KHz to 15 KHz are applied to the electrodes of the transporting base plate which performs hopping of the fine particles by an electrostatic force.

### Claim 41

A development device comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on a photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body,
wherein a vertical field intensity at a height position corresponding to the average diameter of each fine particle on the surface in the vicinity of the electrode center of the surface of the transporting base plate which performs hopping of the fine particles by an electrostatic force is 1×106V/m or more.

### Claim 42

A development device comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on a photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body,
wherein a spacing between the latent image carrier and the surface of the transporting base plate which performs hopping of the fine particles by an electrostatic force is in a range of 2 to 10 times a hopping height of the fine particles.

### Claim 43

A development device comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on a photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body,
wherein a spacing between the latent image carrier and the surface of the transporting base plate which performs hopping of the fine particles by an electrostatic force is in a range of ½ to 2 times a hopping height of the fine particles.

### Claim 44

An image formation apparatus comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on a photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body,
wherein the transporting base plate has an inorganic or organic surface protective layer covering the electrodes, and the thickness of the surface protective layer does not exceed 10 μm,
wherein the surface protective layer comprises a single layer or a plurality of layers, at least the outermost layer of the surface protective layer provided on the transporting base plate is formed from a material positioned in the vicinity of a material used as a charge controlling agent of fine particles on a frictional charge sequence or a material positioned on a positive end side, and fine particles with a negatively charged polarity is moved.

### Claim 45

An image formation apparatus comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on a photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body,
wherein the transporting base plate has an inorganic or organic surface protective layer covering the electrodes, and the thickness of the surface protective layer does not exceed 10 μm,
wherein the surface protective layer comprises a single layer or a plurality of layers, at least the outermost layer of the surface protective layer provided on the transporting base plate is formed from a material positioned in the vicinity of a material used as a charge controlling agent of fine particles on a frictional charge sequence or a material positioned on a negative end side, and fine particles with a positively charged polarity is moved.

### Claim 46

An image formation apparatus comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on a photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body,
wherein the transporting base plate has an inorganic or organic surface protective layer covering the electrodes, and the thickness of the surface protective layer does not exceed 10 μm,
wherein the outermost surface of the surface protective layer is coarsened.

### Claim 47

An image formation apparatus comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on a photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body,
wherein pulse-like driving waveforms of n phases (n is an integer of 3 or more) or more is applied and a voltage application time per one phase is less than cycle period time×(n−1)/n.

### Claim 48

An image formation apparatus comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on a photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body,
wherein pulse-like driving waveforms of n phases (n is an integer of 3 or more) or more is applied, and a time period when a voltage which repels fine particles is applied to an electrode of a observed phase and a time period when a voltage which repels fine particles is applied to an upstream side electrode adjacent thereto and simultaneously a voltage which attracts fine particles is applied to a downstream side electrode adjacent thereto are set to 30 μsec or more.

### Claim 49

An image formation apparatus comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on a photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body,
wherein a vertical field intensity at a height position corresponding to the average diameter of each fine particle on the surface in the vicinity of the electrode center of the surface of the transporting base plate which performs hopping of the fine particles by an electrostatic force is 1×106 V/m or more.

### Claim 50

An image formation apparatus comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on a photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body,
wherein a spacing between the latent image carrier and the surface of the transporting base plate which performs hopping of the fine particles by an electrostatic force is in a range of 2 to 10 times a hopping height of the fine particles.

### Claim 51

An image formation apparatus comprising:
an electrostatic transportation device which moves fine particles by an electrostatic force, the electrostatic transportation device comprising,
a transporting base plate which has a plurality of electrodes which generate an electric field which performs transporting and hopping of fine particles by an electrostatic force,
wherein a width of each of the electrodes in a traveling direction of the fine particles is set to be in a range of 1 time to 20 times an average particle diameter of the fine particles, a pitch between the electrodes in the traveling direction of the fine particles is set to be in a range of 1 time to 20 times the average particle diameter of the fine particles, driving waveforms of n phases or more (n is an integer of 3 or more) are applied to respective electrodes, a driving voltage applied to the electrodes and a voltage of latent image section formed on a photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the latent image section attracts the fine particles towards the photosensitive body, and the driving voltage and a voltage of a non-latent image section formed on the photosensitive body are set such that an electric field generated by the driving voltage and the voltage of the non-latent image section repels the fine particles from the photosensitive body,
wherein a spacing between the latent image carrier and the surface of the transporting base plate which performs hopping of the fine particles by an electrostatic force is in a range of ½ to 2 times a hopping height of the fine particles.