Toner flight controlling method for an image forming aparatus

Claim 2

An image forming apparatus comprising: a visualizing particle carrier for carrying visualizing particles; a counter electrode provided vis-a-vis said visualizing particle carrier; a control electrode provided between said visualizing particle carrier and said counter electrode; power supply means for applying a flight electric field-use voltage across said visualizing particle carrier and said counter electrode so that an electric field for causing the visualizing particles to fly from said visualizing particle carrier toward said counter electrode is generated; control voltage applying means for applying a control voltage to said control electrode so that the flight of the visualizing particles is controlled in accordance with an image signal; a recording medium transport route through which a recording medium is transported while being in contact with said control electrode, the recording medium transport route being provided between said control electrode and said counter electrode, the visualizing particles adhering to the recording medium; and control means for controlling said power supply means and control voltage applying means, so that: during a non-operational period while the flight electric field-use voltage and the control voltage are not applied, said visualizing particle carrier, said counter electrode, and said control electrode have the same potential as a ground potential of said image forming apparatus; during an operational period while the flight electric field-use voltage and the control voltage are applied, said visualizing particle carrier, said counter electrode, and said control electrode are respectively set to have a bias potential of said visualizing particle carrier, the bias potential being set to have a value nearer to the ground potential than to the potential of said counter electrode and a polarity of said counter electrode during the application of the flight electric field-use voltage, then, a flight suppressing voltage in the control voltages is applied to said control electrode, the flight suppressing voltage for suppressing the flight of the visualizing particles, and thereafter the flight electric field-use voltage is applied across said counter electrode and said visualizing particle carrier; and when the application of the flight electric field-use voltage and the control voltage is suspended, the flight suppressing voltage in the control voltages is applied to said control electrode, then the application of the flight electric field-use voltage is suspended, and thereafter the application of the flight suppressing voltage is suspended.

Claim 3

An image forming apparatus comprising: a visualizing particle carrier for carrying visualizing particles; a counter electrode provided vis-a-vis said visualizing particle carrier; a control electrode provided between said visualizing particle carrier and said counter electrode; power supply means for applying a flight electric field-use voltage across said visualizing particle carrier and said counter electrode so that an electric field for causing the visualizing particles to fly from said visualizing particle carrier toward said counter electrode is generated; control voltage applying means for applying a control voltage to said control electrode so that the flight of the visualizing particles is controlled in accordance with an image signal; a recording medium transport route through which a recording medium is transported while being in contact with said counter electrode, the recording medium transport route being provided between said control electrode and said counter electrode, the visualizing particles adhering to the recording medium; cleaning means for removing foreign material adhering to a surface of said counter electrode; and cleaning process control means for causing a foreign material flying electric field to be generated at least either before the image formation starts or after the image formation ends, the electric field causing the foreign material adhering to said control electrode to fly toward said counter electrode.

Claim 4

The image forming apparatus as set forth in claim 3, wherein said cleaning process control means applies an alternating voltage to said counter electrode so that the electric field is generated.

Claim 5

The image forming apparatus as set forth in claim 4, wherein the alternating voltage has a peak value set to the potential of said counter electrode when the flight electric field-use voltage is applied, and a bottom value set not higher than the ground potential of the image forming apparatus.

Claim 6

The image forming apparatus as set forth in claim 3, wherein, in the case where the foreign material flying electric field is generated both before and after the image formation, said cleaning process control means controls the foreign material flying electric field so that the electric field is generated for a longer period after the image formation than before the image formation.

Claim 7

An image forming apparatus comprising: a visualizing particle carrier for carrying visualizing particles; a counter electrode provided vis-a-vis said visualizing particle carrier; a control electrode provided between said visualizing particle carrier and said counter electrode; power supply means for applying a flight electric field-use voltage across said visualizing particle carrier and said counter electrode so that an electric field for causing the visualizing particles to fly from said visualizing particle carrier toward said counter electrode is generated; control voltage applying means for applying a control voltage to said control electrode so that the flight of the visualizing particles is controlled in accordance with an image signal; a recording medium transport route through which a recording medium is transported while being in contact with said counter electrode, the recording medium transport route being provided between said control electrode and said counter electrode, the visualizing particles adhering to the recording medium; and charge removing means for removing electric charges of said control electrode.

Claim 8

The image forming apparatus as set forth in claim 7, wherein said charge removing means removes the electric charges before the image formation.

Claim 9

The image forming apparatus as set forth in claim 7, wherein: said control electrode includes an insulating layer, a plurality of gates provided in said insulating layer, and a plurality of electrode sections, each electrode section being provided around each gate, visualizing particles being allowed to pass through said gates, the control voltage being applied to said electrode sections; said charge removing means includes a resistive layer and a connecting circuit, said resistive layer being provided on at least one surface of said insulating layer, said connecting circuit electrically connecting or disconnecting said resistive layer to an object so that electric charges of said resistive layer are released through the object during connecting; and said resistive layer has a limited resistance such that a surface resistance of said resistive layer is smaller than that of said insulating layer and that a time constant derived from the surface resistance of said resistive layer and a capacitance between the electrode sections is greater than a voltage control cycle of said control electrode.

Claim 10

The image forming apparatus as set forth in claim 9, wherein said connecting circuit connects or disconnects said resistive layer to said visualizing particle carrier.

Claim 11

The image forming apparatus as set forth in claim 9, wherein said connecting circuit connects or disconnects said resistive layer to a ground terminal of said image forming apparatus.

Claim 12

The image forming apparatus as set forth in claim 9, wherein said resistive layer is provided in contact with said electrode sections.

Claim 13

The image forming apparatus as set forth in claim 7, wherein: said control electrode includes a plurality of gates and a plurality of electrode sections, each electrode section being provided around each gate, visualizing particles being allowed to pass through said gates, the control voltage being applied to said electrode sections; said charge removing means includes a resistive layer, said electrode sections being provided on said resistive layer; and said resistive layer has a limited resistance such that a surface resistance of said resistive layer is smaller than that of said insulating layer and that a time constant derived from the surface resistance of said resistive layer and a capacitance between the electrode sections is greater than a voltage control cycle of said control electrode.

Claim 14

The image forming apparatus as set forth in claim 7, wherein: said control electrode includes an insulating layer, a plurality of gates provided in said insulating layer, and a plurality of electrode sections, each electrode section being provided around each gate, visualizing particles being allowed to pass through said gates, the control voltage being applied to said electrode sections; and said charge removing means includes: a photoconductive layer provided on at least one surface of said insulating layer, said photocoductive layer having a resistance decreasing upon receipt of light, a connecting circuit for electrically connecting or disconnecting said photoconductive layer to an object so that electric charges of said photoconductive layer are released through the object during connecting, and a light source for projecting the light on said photoconductive layer.

Claim 15

The image forming apparatus as set forth in claim 14, wherein said connecting circuit connects or disconnects said photoconductive layer to said visualizing particle carrier.

Claim 16

The image forming apparatus as set forth in claim 14, wherein said photoconductive layer is provided in contact with said electrode sections.

Claim 17

The image forming apparatus as set forth in claim 7, wherein: said control electrode includes a plurality of gates and a plurality of electrode sections, each electrode section being provided around each gate, visualizing particles being allowed to pass through said gates, the control voltage being applied to said electrode sections; and said charge removing means includes a photoconductive layer on which said electrode sections are provided, and a light source for projecting light on said photoconductive layer.

Claim 18

An image forming apparatus comprising: a visualizing particle carrier for carrying visualizing particles; a counter electrode provided vis-a-vis said visualizing particle carrier; a control electrode provided between said visualizing particle carrier and said counter electrode; power supply means for applying a flight electric field-use voltage across said visualizing particle carrier and said counter electrode so that an electric field for causing the visualizing particles to fly from said visualizing particle carrier toward said counter electrode is generated; control voltage applying means for applying a control voltage to said control electrode so that the flight of the visualizing particles is controlled in accordance with an image signal; a recording medium transport route through which a recording medium is transported while being in contact with said counter electrode, the recording medium transport route being provided between said control electrode and said counter electrode, the visualizing particles adhering to the recording medium; a connecting circuit for connecting said visualizing particle carrier to a ground terminal of said image forming apparatus through a resistor with a limited resistance; and switching means, provided in said connecting circuit, for switching said connecting circuit so as to connect said visualizing particle carrier to the ground terminal when no voltage is applied to said visualizing particle carrier, while disconnecting when a voltage is applied to said visualizing particle carrier.

Claim 19

An image forming apparatus comprising: a visualizing particle carrier for carrying visualizing particles; a counter electrode provided vis-a-vis said visualizing particle carrier; a control electrode provided between said visualizing particle carrier and said counter electrode; power supply means for applying a flight electric field-use voltage across said visualizing particle carrier and said counter electrode so that an electric field for causing the visualizing particles to fly from said visualizing particle carrier toward said counter electrode is generated; control voltage applying means for applying a control voltage to said control electrode so that the flight of the visualizing particles is controlled in accordance with an image signal; a recording medium transport route through which a recording medium is transported while being in contact with said counter electrode, the recording medium transport route being provided between said control electrode and said counter electrode, the visualizing particles adhering to the recording medium; a connecting circuit for connecting said visualizing particle carrier to said counter electrode through a resistor with a limited resistance; and switching means, provided in said connecting circuit, for switching said connecting circuit so as to connect said visualizing particle carrier to said counter electrode when said flight electric field-use voltage is not applied to said visualizing particle carrier, while disconnecting when said flight electric field-use voltage is applied to said visualizing particle carrier.

Claim 20

An image forming apparatus comprising: a visualizing particle carrier for carrying visualizing particles; a control electrode provided so as to face said visualizing particle carrier; a counter electrode provided so as to face said visualizing particle carrier, with said control electrode provided between said visualizing particle carrier and said counter electrode, said counter electrode including an extension section extending in a recording medium transport direction at least on a downstream side of a portion of said counter electrode facing an image forming region where the visualizing particles fly from said visualizing particle carrier under the control of said control electrode; power supply means for applying a flight electric field-use voltage across said visualizing particle carrier and said counter electrode so that an electric field for causing the visualizing particles to fly from said visualizing particle carrier toward said counter electrode is generated; control voltage applying means for applying a control voltage to said control electrode so that the flight of the visualizing particles is controlled in accordance with an image signal; a recording medium transport route through which a recording medium is transported while being in contact with said counter electrode, the recording medium transport route being provided between said control electrode and said counter electrode, the visualizing particles adhering to the recording medium; and fixing means for fixing the visualizing particles on the recording medium, said fixing means being provided on a downstream side of said recording medium transport route in the recording medium transport direction.

Claim 21

The image forming apparatus as set forth in claim 20, wherein said extension section of said counter electrode has an end portion on the downstream side of the recording medium transport direction, and the end portion is father on the downstream side of the recording medium transport direction than an end portion of said control electrode.

Claim 22

An image forming apparatus as set forth in claim 20 further comprising a conductive shield member, facing said counter electrode, provided in a position farther on the downstream side of said control electrode in the recording medium transport direction than the image forming region, on a surface side of said control electrode facing said counter electrode,.

Claim 23

The image forming apparatus as set forth in claim 22, wherein a voltage is applied to said shield member during the image formation, the voltage generating an electric field so as to cause the visualizing particles adhering to the recording medium to be pressed on the recording medium.

Claim 24

The image forming apparatus as set forth in claim 23, wherein the voltage applied to the shield member is a voltage allowing the visualizing particles to fly instead of a voltage suppressing the visualizing particles to fly, the voltages allowing and suppressing the visualizing particles to fly being applied by said control voltage applying means to said control electrode.

Claim 25

The image forming apparatus as set forth in claim 20, wherein said control electrode is arranged so that a portion of said control electrode corresponding to the image forming region is closer to said counter electrode than the other portions of said control electrode.

Claim 26

An image forming apparatus comprising: a visualizing particle carrier for carrying visualizing particles; a control electrode provided so as to face said visualizing particle carrier; a counter electrode provided so as to face said visualizing particle carrier, with said control electrode provided between said visualizing particle carrier and said counter electrode, said counter electrode including a first area facing an image forming region where the visualizing particles are caused to fly from said visualizing particles carrier under the control of said control electrode, and a second area provided on a downstream side of the first area in a recording medium transport direction, said first area having a predetermined potential in accordance with a voltage applied by power supplying means, said second area having a potential gradually decreasing from the upstream side to the downstream side, said power supply means applying a flight electric field-use voltage across said visualizing particle carrier and said counter electrode so that an electric field for causing the visualizing particles to fly from said visualizing particle carrier toward said counter electrode is generated; control voltage applying means for applying a control voltage to said control electrode so that the flight of the visualizing particles is controlled in accordance with an image signal; a recording medium transport route through which a recording medium is transported while being in contact with said counter electrode, the recording medium transport route being provided between said control electrode and said counter electrode, the visualizing particles adhering to the recording medium; and fixing means for fixing the visualizing particles on the recording medium, said fixing means being provided on a downstream side of said recording medium transport route in the recording medium transport direction.

Claim 27

The image forming apparatus as set forth in claim 26, wherein said first area of said counter electrode is a conductive area, while said second area of said counter electrode is a high-resistive area, said conductive section is connected to said power supply means, an end portion on an upstream side of said high-resistive area in the recording medium transport direction is connected to said conductive area, while an end portion on a downstream side of said high-resistive area is connected to a ground terminal of said image forming apparatus.

Claim 28

The image forming apparatus as set forth in claim 26, wherein said counter electrode includes an endless resistive belt made of a substance having an electric resistance, and first through third conductive members, which are provided so that: said resistive belt is rotatively provided through said first and third conductive members, so as to extend from the image forming region toward the downstream of the recording medium transport direction; said first, third, and second conductive members are provided in this order in the recording medium transport direction, so as to be in contact with a rear surface of a section on a side of said control electrode of said resistive belt, the section of said resistive belt moving in the recording medium transport direction; and said third conductive member provided so that space between said first and third conductive members faces the image forming region, wherein said first and third conductive members are respectively connected to said power supply means, and said second conductive member is connected to a ground terminal of said image forming apparatus.

Claim 29

The image forming apparatus as set forth in claim 28, wherein: said first and second conductive members are conductive rollers for rotatably supporting said resistive belt at its both ends; and said third conductive member is a conductive roller which rotates while being in contact with the rear surface of said resistive belt.

Claim 30

The image forming apparatus as set forth in claim 28, wherein: said first and second conductive members are conductive rollers for rotatably supporting said resistive belt at its both ends; and said third conductive member is a conductive brush provided in contact with the rear surface of said resistive belt.

Claim 31

The image forming apparatus as set forth in claim 26, wherein said control electrode is arranged so that a portion of said control electrode corresponding to the image forming region is closer to said counter electrode than the other portions of said control electrode.