Charging device and image forming apparatus provided therewith
First Claim
1. A charging device comprising:
- a charging member opposed to an outer circumferential surface of a rotating object to be charged; and
a voltage applying section for applying a pulsating voltage obtained by superimposing a voltage component of a direct current on a voltage component that periodically changes between the charging member and the object to be charged, wherein a relation of
Vpp≦
|Vth|is satisfied, where Vpp is a peak-to-peak voltage value of the pulsating voltage, and Vth is a charging start voltage value of the object to be charged.
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Accused Products
Abstract
An image forming apparatus has a charging member opposed to an outer circumferential surface of a rotating object to be charged. The image forming apparatus has a voltage applying section for applying a pulsating voltage Vsp between the charging member and the object to be charged. The pulsating voltage Vsp is obtained by superimposing a voltage component of a direct current on a voltage component that periodically changes. The image forming apparatus is made to satisfy a relation of Vpp≦|Vth|, where Vpp is a peak-to-peak voltage value of the pulsating voltage Vsp and Vth is a charging start voltage value of the object to be charged. The relation prevents opposite charge from being imparted to residual toner on the object to be charged.
7 Citations
21 Claims
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1. A charging device comprising:
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a charging member opposed to an outer circumferential surface of a rotating object to be charged; and
a voltage applying section for applying a pulsating voltage obtained by superimposing a voltage component of a direct current on a voltage component that periodically changes between the charging member and the object to be charged, wherein a relation of
Vpp≦
|Vth|is satisfied, where Vpp is a peak-to-peak voltage value of the pulsating voltage, and Vth is a charging start voltage value of the object to be charged. - View Dependent Claims (2, 3)
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4. A charging device comprising:
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a charging member opposed to an outer circumferential surface of a rotating object to be charged; and
a voltage applying section for applying a pulsating voltage obtained by superimposing a voltage component of a direct current on a voltage component that periodically changes between the charging member and the object to be charged, wherein a relation of
|Vmax−
Vo|>
|Vth|>
|Vmin−
Vo|is satisfied, where Vth is a charging start voltage value of the object to be charged, Vo is each voltage of the charged object surface located both upstream and downstream of the charging member in relation to a movement direction of the outer circumferential surface of the object to be charged, Vmax is a maximum value of the pulsating voltage, and Vmin is a minimum value of the pulsating voltage. - View Dependent Claims (5, 6)
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7. A charging device comprising:
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a charging member opposed to an outer circumferential surface of a rotating object to be charged; and
a charge control member opposed to the object to be charged in a position located upstream of the charging member in relation to a movement direction of the outer circumferential surface of the object to be charged; and
a voltage applying section for applying voltages for controlling a surface voltage of the object to be charged, between the charge control member and the object to be charged and between the charging member and the object to be charged, respectively, wherein the voltages are applied so that a relation of
|Vo(i)|<
|Vo(ii)|<
|Vo(iii)|is satisfied, where Vo(i) is a voltage of the charged object surface located upstream of the charge control member, Vo(ii) is a voltage of the charged object surface located downstream of the charge control member and upstream of the charging member, and Vo(iii) is a voltage of the charged object surface located downstream of the charging member. - View Dependent Claims (8, 9)
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10. An image forming apparatus of an electrophotographic system, comprising:
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a charging device for uniformly charging an outer circumferential surface of an electrostatic latent image carrier that serves as a rotating object to be charged, the charging device comprising;
a charging member opposed to the outer circumferential surface of the electrostatic latent image carrier; and
a voltage applying section for applying a pulsating voltage obtained by superimposing a voltage component of a direct current on a voltage component that periodically changes between the charging member and the electrostatic latent image carrier, wherein a relation of
Vpp≦
|Vth|is satisfied, where Vpp is a peak-to-peak voltage value of the pulsating voltage, and Vth is a charging start voltage value of the electrostatic latent image carrier, an exposure device for forming a latent image by exposing the outer circumferential surface of the electrostatic latent image carrier;
a developing device for developing the latent image by making toner adhere to the latent image; and
a transfer device for transferring the toner onto an object to receive transfer. - View Dependent Claims (11, 12, 13)
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14. An image forming apparatus of an electrophotographic system comprising:
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a charging device for uniformly charging an outer circumferential surface of an electrostatic latent image carrier that serves as a rotating object to be charged, the charging device comprising;
a charging member opposed to the outer circumferential surface of the electrostatic latent image carrier; and
a voltage applying section for applying a pulsating voltage obtained by superimposing a voltage component of a direct current on a voltage component that periodically changes between the charging member and the electrostatic latent image carrier, wherein a relation of
|Vmax−
Vo|>
|Vth|>
|Vmin−
Vo|is satisfied, where Vth is a charging start voltage value of the electrostatic latent image carrier, Vo is each voltage of the electrostatic latent image carrier surface located upstream and downstream of the charging member in relation to a movement direction of the outer circumferential surface of the electrostatic latent image carrier, Vmax is a maximum value of the pulsating voltage, and Vmin is a minimum value of the pulsating voltage, an exposure device for forming a latent image by exposing the outer circumferential surface of the electrostatic latent image carrier;
a developing device for developing the latent image by making toner adhere to the latent image; and
a transfer device for transferring the toner onto an object to receive transfer. - View Dependent Claims (15, 16, 17)
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18. An image forming apparatus of an electrophotographic system comprising:
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a charging device for uniformly charging an outer circumferential surface of an electrostatic latent image carrier that serves as a rotating object to be charged, the charging device comprising;
a charging member opposed to the outer circumferential surface of the electrostatic latent image carrier;
a charge control member opposed to the electrostatic latent image carrier in a position located upstream of the charging member in relation to a movement direction of the outer circumferential surface of the electrostatic latent image carrier; and
a voltage applying section for applying voltages for controlling a surface voltage of the electrostatic latent image carrier between the charge control member and the electrostatic latent image carrier and between the charging member and the electrostatic latent image carrier, respectively, wherein the voltages are applied so that a relation of
|Vo(i)|<
|Vo(ii)|<
|Vo(iii)|is satisfied, where Vo(i) is a voltage of the electrostatic latent image carrier surface located upstream of the charge control member, Vo(ii) is a voltage of the electrostatic latent image carrier surface located downstream of the charge control member and upstream of the charging member, and Vo(iii) is a voltage of the electrostatic latent image carrier surface located downstream of the charging member, an exposure device for forming a latent image by exposing the outer circumferential surface of the electrostatic latent image carrier;
a developing device for developing the latent image by making toner adhere to the latent image; and
a transfer device for transferring the toner onto an object to receive transfer. - View Dependent Claims (19, 20, 21)
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Specification