Image forming apparatus

An image forming apparatus comprising:

• an image carrier;
• latent image forming means for uniformly charging a surface of said image carrier and then exposing said surface in accordance with image data to thereby form a latent image on said surface;
• a developing device for causing a developer carrier to convey a developer deposited on said developer carrier and containing toner to a developing region where said developer carrier faces said image carrier, said developer developing the latent image to thereby form a corresponding toner image;
• bias applying means for applying a bias VB for development to said developer carrier;
• and
• transferring means for transferring the toner image from said image carrier to a recording medium;
• wherein a charge potential deposited on said image carrier is 400 V or below in absolute value, and
• assuming that a potential of said image carrier is lowered to VL in an exposed portion, that a development potential is |VB−VL|, that a maximum set value of said development potential to be used for development is |VB−VL|max, and that said development potential varies in a range satisfying relations:
• |VB−VL|≦|VB−VL|max+50 V (1)
• |VB−VL|≧|VB−VL|max−50 V (2)
• |VB−VL|max≦300 V (3)
• then image density varies by a width of 10% of image density corresponding to the maximum set value of the development potential or less.

An image forming apparatus comprising:

• an image carrier;
• latent image forming means for uniformly charging a surface of said image carrier and then exposing said surface in accordance with image data to thereby form a latent image on said surface;
• a developing device for causing a developer carrier to convey a developer deposited on said developer carrier and containing toner to a developing region where said developer carrier faces said image carrier, said developer developing the latent image to thereby form a corresponding toner image;
• bias applying means for applying a bias VB for development to said developer carrier;
• and
• transferring means for transferring the toner image from said image carrier to a recording medium;
• wherein a charge potential deposited on said image carrier is 400 V or below in absolute value, and
• assuming that a potential of said image carrier is lowered to VL in an exposed portion, that a development potential is |VB−VL|, that a maximum set value of said development potential to be used for development is |VB−VL|max, and that said development potential varies in a range satisfying relations:
• |VB−VL|≦|VB−VL|max+|VB−VL|max×0.2 (1)
• |VB−VL|≧|VB−VL|max−|VB−VL|max×0.2 (2)
• |VB−VL|max≦300 V (3)
• then image density varies by a width lying in a range of ±0.1 of image density corresponding to the maximum set value of the development potential or less.

An image forming apparatus comprising:

• an image carrier;
• latent image forming means for uniformly charging a surface of said image carrier and then exposing said surface in accordance with image data to thereby form a latent image on said surface;
• a developing device for causing a developer carrier to convey a developer deposited on said developer carrier and containing toner to a developing region where said developer carrier faces said image carrier, said developer developing the latent image to thereby form a corresponding toner image;
• bias applying means for applying a bias VB for development to said developer carrier;
• and
• transferring means for transferring the toner image from said image carrier to a recording medium;
• wherein the bias VB, a lowered potential VL of an exposed portion of said image carrier and a potential VD of an unexposed portion of said image carrier satisfy a relation:
• 0<|VD|−|VB|<|VD−VL|<250 V (1)
• and
• assuming that a minimum amount X of toner deposition implementing saturation image density on said image carrier is expressed as:
• X=0.6×toner grain size×toner true specific gravity/transfer ratio (2)
• then a maximum amount of toner to deposit on said image carrier is 1.5×X or less.

In an image forming process unit removably mounted to an image forming apparatus and comprising an image carrier and at least one of a charger constituting latent image forming means, a cleaning device and a developing device, said image forming apparatus comprising:

• an image carrier;
• latent image forming means for uniformly charging a surface of said image carrier and then exposing said surface in accordance with image data to thereby form a latent image on said surface;
• a developing device for causing a developer carrier to convey a developer deposited on said developer carrier and containing toner to a developing region where said developer carrier faces said image carrier, said developer developing the latent image to thereby form a corresponding toner image;
• bias applying means for applying a bias VB for development to said developer carrier;
• and
• transferring means for transferring the toner image from said image carrier to a recording medium;
• wherein a charge potential deposited on said image carrier is 400 V or below in absolute value, and
• assuming that a potential of said image carrier is lowered to VL in an exposed portion, that a development potential is |VB−VL|, that a maximum set value of said development potential to be used for development is |VB−VL|max, and that said development potential varies in a range satisfying relations:
• |VB−VL|≦|VB−VL|max+|VB−VL|max×0.2 (1)
• |VB−VL|≧|VB−VL|max−|VB−VL|max×0.2 (2)
• |VB−VL|max≦300 V (3)
• then image density varies by a width of 10% of image density corresponding to the maximum set value of the development potential or less.

In an image forming process unit removably mounted to an image forming apparatus and comprising an image carrier and at least one of a charger constituting latent image forming means, a cleaning device and a developing device, said image forming apparatus comprising:

• an image carrier;
• latent image forming means for uniformly charging a surface of said image carrier and then exposing said surface in accordance with image data to thereby form a latent image on said surface;
• a developing device for causing a developer carrier to convey a developer deposited on said developer carrier and containing toner to a developing region where said developer carrier faces said image carrier, said developer developing the latent image to thereby form a corresponding toner image;
• bias applying means for applying a bias VB for development to said developer carrier;
• and
• transferring means for transferring the toner image from said image carrier to a recording medium;
• wherein a charge potential deposited on said image carrier is 400 V or below in absolute value, and
• assuming that a potential of said image carrier is lowered to VL in an exposed portion, that a development potential is |VB−VL|, that a maximum set value of said development potential to be used for development is |VB−VL|max, and that said development potential varies in a range satisfying relations:
• |VB−VL|≦|VB−VL|max+50 V (1)
• |VB−VL|≧|VB−VL|max−50 V (2)
• |VB−VL|max≦300 V (3)
• then image density varies by a width of 10% of image density corresponding to the maximum set value of the development potential or less.

In an image forming process unit removably mounted to an image forming apparatus and comprising an image carrier and at least one of a charger constituting latent image forming means, a cleaning device and a developing device, said image forming apparatus comprising:

• an image carrier;
• latent image forming means for uniformly charging a surface of said image carrier and then exposing said surface in accordance with image data to thereby form a latent image on said surface;
• a developing device for causing a developer carrier to convey a developer deposited on said developer carrier and containing toner to a developing region where said developer carrier faces said image carrier, said developer developing the latent image to thereby form a corresponding toner image;
• bias applying means for applying a bias VB for development to said developer carrier;
• and
• transferring means for transferring the toner image from said image carrier to a recording medium;
• wherein a charge potential deposited on said image carrier is 400 V or below in absolute value, and
• assuming that a potential of said image carrier is lowered to VL in an exposed portion, that a development potential is |VB−VL|, that a maximum set value of said development potential to be used for development is |VB−VL|max, and that said development potential varies in a range satisfying relations:
• |VB−VL|≦|VB−VL|max+|VB−VL|max×0.2 (1)
• |VB−VL|≧|VB−VL|max−|VB−VL|max×0.2 (2)
• |VB−VL|max≦300 V (3)
• then image density varies by a width lying in a range of ±0.1 of image density corresponding to the maximum set value of the development potential or less.

In an image forming process unit removably mounted to an image forming apparatus and comprising an image carrier and at least one of a charger constituting latent image forming means, a cleaning device and a developing device, said image forming apparatus comprising:

• an image carrier;
• latent image forming means for uniformly charging a surface of said image carrier and then exposing said surface in accordance with image data to thereby form a latent image on said surface;
• a developing device for causing a developer carrier to convey a developer deposited on said developer carrier and containing toner to a developing region where said developer carrier faces said image carrier, said developer developing the latent image to thereby form a corresponding toner image;
• bias applying means for applying a bias VB for development to said developer carrier;
• and
• transferring means for transferring the toner image from said image carrier to a recording medium;
• wherein the bias VB, a lowered potential VL of an exposed portion of said image carrier and a potential VD of an unexposed portion of said image carrier satisfy a relation:
• 0<|VD|−|VB|<|VD−VL|<250 V (1)
• and
• assuming that a minimum amount X of toner deposition implementing saturation image density on said image carrier is expressed as:
• X=0.6×toner grain size×toner true specific gravity/transfer ratio (2)
• then a maximum amount of toner to deposit on said image carrier is 1.5×X or less.