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US 7,271,824 B2Granted
Pixel clock generating apparatus, optical writing apparatus using a pixel clock, imaging apparatus, and method for generating pixel clocks
AssigneeRicoh Company, Ltd.
InventorsAtsufumi Omori, Masaaki Ishida, Yasuhiro Nihei, Yoshinori Hayashi
Life of this patent
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Abstract
A pixel clock generating apparatus includes a data offset circuit and a pixel generator. The data offset circuit defines multiple data blocks, each data block consisting of a predetermined number of successive clocks, and produces phase data for each data block. The phase data represents an amount and a direction of phase shift to be carried out for a certain clock in each data block. The pixel generator receives the phase data from the data offset circuit and generates a phase-shifted pixel clock a predetermined number of times in each data block based on the phase data.
Claims35
A pixel clock generating apparatus used in an optical writing system for optically producing an image at timing of a pixel clock, the pixel clock generating apparatus comprising:
- a data offset circuit configured to define multiple data blocks, each of the data blocks consisting of a predetermined number of successive clocks, and to produce phase data for each of the data blocks, the phase data representing an amount and a direction of phase shift made to a certain clock in each of the data blocks;
- and
- a pixel generator configured to receive the phase data from the data offset circuit and generate a phase-shifted pixel clock a predetermined number of times in each of the data blocks based on the phase data,
- wherein the data offset circuit comprises:
- a data block setting unit configured to determine said predetermined number of successive clocks in each of the data blocks,
- a phase data generating unit configured to produce the phase data for each of the data blocks based on said predetermined number of clocks and phase shift data, the phase shift data representing a number of times phase shift is to be carried out in each of the data blocks, and
- a data block setting value storage configured to store a data block setting value determined for each of the data blocks at an associated image height based on a dot offset characteristic of the optical writing system that has been measured in advance, and to read and supply the data block setting value for each of the data blocks to the data block setting unit and the phase data generating unit.
4 more elements
An optical writing apparatus comprising:
- a light source configured to emit a beam;
- a photosensitive unit on which an image is optically formed;
- an optical scanning system configured to guide the beam onto the photosensitive unit and let the beam scan along a scanning line on the photosensitive unit;
- a pixel clock generating unit configured to generate a pixel clock;
- and
- a light source driving unit configured to drive the light source based on the pixel clock, wherein the pixel clock generating unit comprises:
- a data offset circuit configured to define multiple data blocks within an effective scanning period, each of the data blocks consisting of a predetermined number of successive clocks, and to produce phase data for each of the data blocks, the phase data representing an amount and a direction of phase shift made to a certain clock in each of the data blocks;
- and
- a pixel generator configured to receive the phase data from the data offset circuit and generate a phase-shifted pixel clock based on the phase data,
- wherein the data offset circuit comprises:
- a data block setting unit configured to determine said predetermined number of successive clocks in each of the data block, and
- a phase data generating unit configured to produce the phase data for each of the data blocks based on said predetermined number of clocks and phase shift data, the phase shift data representing a number of times phase shift is to be carried out in each of the data blocks,
- wherein the predetermined number of successive clocks defining each data block is variable according to a dot offset measured in the main scanning direction, and
- a data block setting value storage configured to store a data block setting value determined for each of the data blocks at an associated image height based on a dot offset characteristic of the optical writing system that has been measured in advance, and to read and supply the data block setting value for each of the data blocks to the data block setting unit and the phase data generating unit.
11 more elements
An imaging apparatus comprising:
- an optical writing unit configured to optically form a latent image;
- and
- an image reproducing unit configured to reproduce the latent image as a visible image, the optical writing unit comprising:
- a light source configured to emit a beam;
- a photosensitive unit on which the latent image is formed;
- an optical scanning system configured to guide the beam onto the photosensitive unit and let the beam scan along a scanning line on the photosensitive unit;
- and
- a pixel clock generating unit configured to generate a pixel clock and comprising:
- a data offset circuit configured to define multiple data blocks within an effective scanning period, each of the data blocks consisting of a predetermined number of successive clocks, and to produce phase data for each of the data blocks, the phase data representing an amount and a direction of phase shift made to a certain clock in each data block;
- and
- a pixel generator configured to receive the phase data from the data offset circuit and generate a phase-shifted pixel clock based on the phase data,
- wherein the data offset circuit comprises:
- a data block setting unit configured to determine said predetermined number of successive clocks in each of the data block, and
- a phase data generating unit configured to produce the phase data for each of the data blocks based on said predetermined number of clocks and phase shift data, the phase shift data representing a number of times phase shift is to be carried out in each of the data blocks,
- wherein the predetermined number of successive clocks defining each data block is variable according to a dot offset measured in the main scanning direction, and
- a data block setting value storage configured to store a data block setting value determined for each of the data blocks at an associated image height based on a dot offset characteristic of the optical writing system that has been measured in advance, and to read and supply the data block setting value for each of the data blocks to the data block setting unit and the phase data generating unit.
13 more elements
An imaging apparatus comprising:
- multiple optical writing units corresponding to multiple colors, each configured to optically form a latent image of an associated color;
- and
- an image reproducing unit for reproducing a color image based on the latent images formed by the optical writing units, each of the optical writing units comprising:
- a light source configured to emit a beam;
- a photosensitive unit on which the latent image is formed;
- an optical scanning system configured to guide the beam onto the photosensitive unit and let the beam scan along a scanning line on the photosensitive unit;
- and
- a pixel clock generating unit configured to generate a pixel clock, the pixel clock generating unit comprising a data offset circuit that defines multiple data blocks within an effective scanning period, each data block consisting of a predetermined number of successive clocks, and produces phase data for each of the data blocks, the phase data representing an amount and a direction of phase shift made to a certain clock in each of the data blocks, and a pixel generator configured to receive the phase data from the data offset circuit and generate a phase-shifted pixel clock based on the phase data;
- wherein the data offset circuit comprises:
- a data block setting unit configured to determine said predetermined number of successive clocks in each of the data block, and
- a phase data generating unit configured to produce the phase data for each of the data blocks based on said predetermined number of clocks and phase shift data, the phase shift data representing a number of times phase shift is to be carried out in each of the data blocks,
- wherein the predetermined number of successive clocks defining each data block is variable according to a dot offset measured in the main scanning direction, and
- a data block setting value storage configured to store a data block setting value determined for each of the data blocks at an associated image height based on a dot offset characteristic of the optical writing system that has been measured in advance, and to read and supply the data block setting value for each of the data blocks to the data block setting unit and the phase data generating unit.
10 more elements
A method for generating a pixel clock used in an optical writing apparatus when optically writing pixel data, the method comprising:
- defining multiple data blocks, each of the data blocks consisting of a predetermined number of successive clocks;
- producing phase data for each of the data blocks, the phase data representing an amount and a direction of phase shift that is to be made to a certain clock in each of the data blocks;
- generating a phase-shifted pixel clock based on the phase data;
- determining a number of data blocks included in one scanning line so that a difference in dot offset in a main scanning direction among the data blocks does not exceed a prescribed value corresponding to a pixel resolution;
- shifting timing of generating the phase-shifted pixel clock for each of the data blocks every time the optical writing apparatus moves to a next scanning line, incrementing a counter;
- and
- when said shifting of timing of phase-shifted pixel clock is carried out for a prescribed number of scanning lines, resetting the counter.
4 more elements
Dependencies are inferred from the claim text.