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US 10,331,064 B2Granted
Image forming apparatus
AssigneeCanon Kabushiki Kaisha
InventorsYusuke Hirota, Hisashi Nakahara, Akihiko Uchiyama
Life of this patent
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Abstract
In a first image formation mode, an image is formed with a first development contrast C1 and a specific dot pattern is formed with a second development contrast C2, which is lower than the first development contrast C1; in a second image formation mode, an image is formed with a third development contrast C3 and a specific dot pattern is formed with a fourth development contrast C4, which is lower than the third development contrast C3; and when ΔC1 (=C2/C1) denotes a ratio between the second development contrast C2 and the first development contrast C1, and ΔC2 (=C4/C3) denotes a ratio between the fourth development contrast C4 and the third development contrast C3, ΔC2<ΔC1 is satisfied.
Claims15
An image forming apparatus, comprising:
- a rotatable image bearing member on which an electrostatic image is formed;
- a rotatable developer bearing member that supplies a developer to the image bearing member and develops the electrostatic image;
- and
- processing portion that processes image information so as to add a specific dot pattern to an image to be formed on recording material, wherein the image forming apparatus executes:
- a first image formation mode in which an image is formed based on the image information by setting a peripheral velocity ratio Vd/Vdr between a peripheral velocity Vd of the developer bearing member and a peripheral velocity Vdr of the image bearing member to a first peripheral velocity ratio ΔV1;
- and
- a second image formation mode in which an image is formed based on the image information by setting the peripheral velocity ratio Vd/Vdr to a second peripheral velocity ratio ΔV2, which is higher than the first peripheral velocity ratio ΔV1
- in the first image formation mode, the image forming apparatus forms an image by supplying the developer to the image bearing member so that a region corresponding to the image has a first developer volume level M1 and forms the specific dot pattern by supplying the developer to the image bearing member so that a region corresponding to the specific dot pattern has a second developer volume level M2, which is lower than the first developer volume level M1,
- in the second image formation mode, the image forming apparatus forms an image by supplying the developer to the image bearing member so that a region corresponding to the image has a third developer volume level M3 and forms the specific dot pattern by supplying the developer to the image bearing member so that a region corresponding to the specific dot pattern has a fourth developer volume level M4, which is lower than the third developer volume level M3, and
- when ΔM1 (=M2/M1) denotes a ratio between the second developer volume level M2 and the first developer volume level M1, and ΔM2 (=M4/M3) denotes a ratio between the fourth developer volume level M4 and the third developer volume level M3,
- ΔM2<ΔM1 is satisfied.
8 more elements
An image forming apparatus, comprising:
- a rotatable image bearing member on which an electrostatic image is formed;
- a rotatable developer bearing member that supplies a developer to the image bearing member and develops the electrostatic image;
- and
- processing portion that processes image information so as to add a specific dot pattern to an image to be formed on recording material, wherein the image forming apparatus executes:
- a first image formation mode in which an image is formed based on the image information by setting a peripheral velocity ratio Vd/Vdr between a peripheral velocity Vd of the developer bearing member and a peripheral velocity Vdr of the image bearing member to a first peripheral velocity ratio ΔV1;
- and
- a second image formation mode in which an image is formed based on the image information by setting the peripheral velocity ratio Vd/Vdr to a second peripheral velocity ratio ΔV2, which is higher than the first peripheral velocity ratio ΔV1,
- in the first image formation mode, the image forming apparatus forms an image by supplying the developer to the image bearing member so that a region corresponding to the image has a first developer volume level M1 and forms the specific dot pattern by supplying the developer to the image bearing member so that a region corresponding to the specific dot pattern has a second developer volume level M2, which is lower than the first developer volume level M1,
- in the second image formation mode, the image forming apparatus forms an image by supplying the developer to the image bearing member so that a region corresponding to the image has a third developer volume level M3 and forms the specific dot pattern by supplying the developer to the image bearing member so that a region corresponding to the specific dot pattern has a fourth developer volume level M4, which is lower than the third developer volume level M3, and
- when ΔM1 (=|M2−M1|) denotes an absolute value of a difference between the second developer volume level M2 and the first developer volume level M1, and ΔM2 (=|M4−M3|) denotes an absolute value of a difference between the fourth developer volume level M4 and the third developer volume level M3,
- ΔM2 <ΔM1 is satisfied.
8 more elements
An image forming apparatus, comprising:
- an image bearing member on which an electrostatic image is formed;
- a developer bearing member that supplies a developer to the image bearing member and develops the electrostatic image;
- and
- processing portion that processes image information so as to add a specific dot pattern to an image to be formed on recording material, wherein the image forming apparatus executes:
- a first image formation mode in which an image is formed based on the image information by setting a peripheral velocity ratio Vd/Vdr between a peripheral velocity Vd of the developer bearing member and a peripheral velocity Vdr of the image bearing member to a first peripheral velocity ratio ΔV1;
- and
- a second image formation mode in which an image is formed based on the image information by setting the peripheral velocity ratio Vd/Vdr to a second peripheral velocity ratio ΔV2, which is higher than the first peripheral velocity ratio ΔV1,
- wherein, in switching from the first image formation mode to the second image formation mode, density of the specific dot pattern is increased at a rate that is lower than another rate of density increase of a dot pattern of the image other than the specific dot pattern.
5 more elements
Dependencies are inferred from the claim text.