Pulsewidth modulation apparatus, printer, and control method thereof
AssigneeCanon Kabushiki Kaisha
InventorToshiyuki Sekiya
Life of this patent
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Abstract
When pulsewidth modulation is performed with a digital data pattern, appropriate pulsewidth modulation is performed in accordance with variations of a device or a driving system. In a case of inputting data where one pixel is expressed by, e.g., 4 bits (16 tones), a 32-bit pattern having twice as many number of bits as a 16-bit pattern is prepared as a pattern corresponding to input data, and stored in digital data output unit 1001. Pulsewidth addition circuit 1007 is provided for adding a fine-adjustment pulsewidth so as to achieve a target amount of light. The pulsewidth addition circuit 1007 is set so as to achieve a minimum pulsewidth that can generate a laser beam when input data is 0.
Claims12
A pulsewidth modulation apparatus for inputting multivalued pixel data expressed in a plurality of bits, generating a signal having a pulsewidth corresponding to a value of the multivalued pixel data, and outputting the generated signal to a predetermined print engine, comprising:
- storage means arranged to store a digital pattern in an address position corresponding to the value of each multivalued pixel data in order to generate a binary-valued pattern corresponding to the value of the multivalued pixel data;
- and
- output means arranged to access said storage means by using inputted multivalued pixel data as an address to read a corresponding binary-valued pattern, and output a pulsewidth signal corresponding to a state of bits of the pattern,
- wherein the pattern stored in said storage means has a number of bits larger than a number that can be expressed by a number of bits of the inputted multivalued pixel data, and the pattern is rewritable.
An image printing apparatus for printing an image on a printing medium by inputting multivalued pixel data expressed in a plurality of bits, generating a pulsewidth modulation signal having a pulsewidth corresponding to a value of the multivalued pixel data, and outputting the pulsewidth modulation signal to a print engine, comprising:
- storage means arranged to store a digital pattern in an address position corresponding to the value of each multivalued pixel data in order to generate a binary-valued pattern corresponding to the value of the multivalued pixel data;
- and
- output means arranged to access said storage means by using inputted multivalued pixel data as an address to read a corresponding binary-valued pattern, and output a pulsewidth signal corresponding to a state of bits of the pattern,
- wherein the pattern stored in said storage means has a number of bits larger than a number that can be expressed by a number of bits of the inputted multivalued pixel data, and the pattern is rewritable.
A control method of an image printing apparatus for printing an image on a printing medium by outputting a pulsewidth modulation signal to a print engine, said image printing apparatus including:
- input means which inputs multivalued pixel data expressed in a plurality of bits;
- storage means which stores for a value of each multivalued pixel data a binary-valued pattern constructed with a number of bits larger than a maximum value that can be expressed by inputted multivalued pixel data;
- and output means which accesses the storage means by using the inputted multivalued pixel data as an address to read a corresponding binary-valued pattern and outputs a pulsewidth signal corresponding to a state of bits of the pattern,
- said control method comprising the steps of:
- detecting a state of the print engine for each test data by sequentially outputting multivalued pixel test data;
- determining a pattern to be written based on the state detected in said detecting step and a target state;
- and
- storing the determined pattern in the storage means.
Dependencies are inferred from the claim text.