Image forming apparatus operable in color and monochromatic modes

Patent metadata

Field	Value
Publication number	US-10656570-B2
Application number	US-201715654919-A
Country	US
Kind code	B2
Filing date	Jul 20, 2017
Priority date	Jul 21, 2016
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

An image forming apparatus includes a black image forming portion, a color image forming portion, an intermediary transfer member, a transfer portion, and an executing portion capable of executing an operation in a color mode in which a color image is formed using the color image forming portion and the black image forming portion and an operation in a monochromatic mode in which a monochromatic image is formed using only the black image forming portion. The executing portion is capable of forming the monochromatic image in the operation in the monochromatic mode under application of a voltage to the black developing device. The voltage is applied under a voltage condition such that a line width is broader than a line width under a voltage condition inputted to the black developing device when the operation in the color mode is executed.

First claim

What is claimed is:

1. An image forming apparatus comprising:
a black image forming portion configured to form an image with a black toner, said black image forming portion including a black developing device;
a color image forming portion configured to form an image with a yellow toner, a magenta toner, and a cyan toner, said color image forming portion including a yellow developing device, a magenta developing device, and a cyan developing device;
an intermediary transfer member capable of carrying a toner image formed at said black image forming portion and a toner image formed at said color image forming portion;
a transfer portion configured to transfer the toner image from said intermediary transfer member onto a recording material; and
an executing portion capable of executing an operation in a color mode in which a color image is formed on a recording material by using said color image forming portion and said black image forming portion and an operation in a monochromatic mode in which a monochromatic image is formed on a recording material by using only said black image forming portion,
wherein said executing portion is capable of forming the monochromatic image in the operation in the monochromatic mode under application of a voltage to said black developing device, the voltage being applied under a voltage condition, which is inputted to said black developing device when the operation in the monochromatic mode is executed, such that a line width is broader than a line width under a voltage condition which is inputted to said black developing device when the operation in the color mode is executed,
wherein a voltage in the form of an AC voltage biased with a DC voltage is applied to said black developing device, and
wherein said executing portion is capable of forming the image in the operation in the monochromatic mode under application of the AC voltage to said black developing device, the AC voltage having a peak-to-peak voltage of the AC voltage which is inputted to said black developing device when the operation in the monochromatic mode is executed being greater than a peak-to-peak voltage of an AC voltage which is inputted to said black developing device when the operation in the color mode is executed.

2. The image forming apparatus according to claim 1 , further comprising an operating portion configured to operate said image forming apparatus, wherein the monochromatic mode is able to be set using said operating portion.

3. The image forming apparatus according to claim 2 , wherein said operating portion includes a setting portion configured to set the voltage condition which is inputted to said black developing device during the operation in the monochromatic mode.

4. The image forming apparatus according to claim 1 ,
further comprising a common voltage source configured to apply a voltage to said black developing device, said yellow developing device, said magenta developing device, and said cyan developing device.

5. An image forming apparatus comprising:
a black image forming portion configured to form an image with a black toner, said black image forming portion including a black developing device;
a color image forming portion configured to form an image with a yellow toner, a magenta toner, and a cyan toner, said color image forming portion including a yellow developing device, a magenta developing device, and a cyan developing device;
an intermediary transfer member capable of carrying a toner image formed at said black image forming portion and a toner image formed at said color image forming portion;
a transfer portion configured to transfer the toner image from said intermediary transfer member onto a recording material; and
an executing portion capable of executing an operation in a color mode in which a color image is formed on a recording material by using said color image forming portion and said black image forming portion and an operation in a monochromatic mode in which a monochromatic image is formed on a recording material by using only said black image forming portion,
wherein said executing portion is capable of forming the monochromatic image in the operation in the monochromatic mode under application of a voltage to said black developing device, the voltage being applied under a voltage condition, which is inputted to said black developing deice when the operation in the monochromatic mode is executed, such that a line width is broader than a line width under a voltage condition which is inputted to said black developing device when the operation in the color mode is executed,
wherein a voltage in the form of an AC voltage biased with a DC voltage is applied to said black developing device, and
wherein said executing portion is capable of forming the image in the operation in the monochromatic mode under application of the AC voltage to said black developing device, the AC voltage having a frequency of the AC voltage which is inputted to said black developing device when the operation in the monochromatic mode is executed being lower than a voltage frequency of an AC voltage which is inputted to said black developing device when the operation in the color mode is executed.

6. The image forming apparatus according to claim 5 , further comprising an operating portion configured to operate said image forming apparatus,
wherein the monochromatic mode is able to be set using said operating portion.

7. The image forming apparatus according to claim 6 , wherein said operating portion includes a setting portion configured to set the voltage condition which is inputted to said black developing device during the operation in the monochromatic mode.

8. The image forming apparatus according to claim 5 ,
further comprising a common voltage source configured to apply a voltage to said black developing device, said yellow developing device, said magenta developing device, and said cyan developing device.

9. An image forming apparatus comprising:
a black image forming portion configured to form an image with a black toner, said black image forming portion including an image bearing member and a black developing device including a black toner;
a color image forming portion configured to form an image with a yellow toner, a magenta toner, and a cyan toner, said color image forming portion including a yellow developing device, a magenta developing device, and a cyan developing device;
an intermediary transfer member capable of carrying a toner image formed at said black image forming portion and a toner image formed at said color image forming portion;
a transfer portion configured to transfer the toner image from said intermediary transfer member onto a recording material; and
an executing portion capable of executing an operation in a color mode in which a color image is formed on a recording material by using said color image forming portion and said black image forming portion and an operation in a monochromatic mode in which a monochromatic image is formed on a recording material by using only said black image forming portion,
wherein said executing portion is capable of forming the monochromatic image in the operation in the monochromatic mode under application of a voltage to said black developing device, the voltage being applied under a voltage condition, which is inputted to said black developing device when the operation in the monochromatic mode is executed, such that a line width is broader than a line width under a voltage condition which is inputted to said black developing device when the operation in the color mode is executed,
wherein a voltage in the form of an AC voltage biased with a DC voltage is applied to said black developing device, and
wherein said executing por

Assignees

• Canon Kk

Inventors

• Tomine Jun

Classifications

• G03G15/5025

  by measuring the original characteristics, e.g. contrast, density · CPC title

• G03G15/5029

  by measuring the copy material characteristics, e.g. weight, thickness · CPC title

• G03G15/1675 Primary

  with means for controlling the bias applied in the transfer nip · CPC title

• G03G2215/0132

  vertical medium transport path at the secondary transfer · CPC title

• G03G15/0121

  for developing · CPC title