Image forming apparatus and laser beam control method for image forming apparatus
AssigneeCanon Kabushiki Kaisha
InventorsKatsuhide Koga, Fumitaka Sobue
Life of this patent
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Abstract
An image forming apparatus for forming an image by irradiating a charged surface of a photosensitive member with a laser beam depending on a picture signal to form an electrostatic latent image, visualizing the latent image with a recording agent, and transferring the visualized image onto a recording medium; includes a circumferential position detection unit for detecting a circumferential position of the photosensitive member irradiated with the laser beam and an APC circuit for controlling a light quantity of the laser beam so as to provide a target light quantity varying depending on the detected circumferential position.
Claims18
A method of controlling a laser beam for an image forming apparatus of the type wherein an electrostatic latent image is formed by irradiating a charged surface of a photosensitive member with a laser beam depending on a picture signal and is visualized with a recording agent, followed by transfer onto a recording medium to form an image, said method comprising:
- a step of controlling predetermined drive currents supplied from a plurality of current sources including a first current source and a second current source so that a drive current supplied from the first current source is controlled to be constant during one scanning and a drive current supplied from the second current source is switched during one scanning at a plurality of points on the surface of the photosensitive member, based on light quantities of a laser beam at the time of supplying predetermined drive currents from the first and second current sources to predetermined areas, respectively, in a scanning direction of the laser beam at the surface of the photosensitive member.
An image forming apparatus, comprising:
- an image forming unit for irradiating a charged surface of a photosensitive member with a laser beam depending on a picture signal to form an electrostatic latent image, visualizing the latent image with a recording agent, and transferring the visualized image onto a recording medium to form an image,
- a memory for storing a correction value in a main scanning direction of the photosensitive member,
- a circumferential position detection-unit for detecting a circumferential position irradiated with the laser beam at the surface-of the photosensitive member, and
- a control unit for setting a target light quantity depending on the detected circumferential position and controlling a light quantity of the laser beam depending on the correction value stored in the memory and the target light quantity.
An image forming apparatus, comprising:
- an image forming unit for irradiating a charged surface of a photosensitive member with a laser beam depending on a picture signal to form an electrostatic latent image, visualizing the latent image with a recording agent, and transferring the visualized image onto a recording medium to form an image,
- a detection unit for detecting a position in a main scanning direction and a position in a sub scanning direction, at the surface of the photosensitive member irradiated with the laser beam,
- a memory for having combinations of the positions in the main and sub scanning directions at the surface of the photosensitive member as addresses and storing data indicating a target light quantity for each address, and
- a control unit for reading out the target light quantity from the memory depending on a position detected by the detection unit and controlling the laser beam so as to provide the target light quantity.
An image forming apparatus, comprising:
- an image forming unit for irradiating a charged surface of a photosensitive member with a laser beam depending on a picture signal to form an electrostatic latent image, visualizing the latent image with a recording agent, and transferring the visualized image onto a recording medium to form an image,
- a first memory for memorizing a correction value in a main scanning direction of the photosensitive member,
- a second memory for memorizing a correction value in a sub scanning direction of the photosensitive member,
- an arithmetic unit for providing a correction value at a corresponding surface position of the photosensitive member by performing an arithmetic operation of the correction values in the main and sub scanning directions,
- a circumferential position detection unit for detecting a circumferential position of the photosensitive member irradiated with the laser beam, and
- a control unit for controlling the laser beam depending on the correction value provided by the arithmetical unit and the circumferential position detected by the circumferential position detection unit.
Dependencies are inferred from the claim text.