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US 6,498,617 B1Granted
Pulse width modulation circuit, optical write unit, image forming apparatus and optical write method
AssigneeRicoh Company, Ltd.
InventorsMasaaki Ishida, Hidetoshi Ema
Life of this patent
Estimating the term…
Abstract
A pulse width modulation circuit is provided with a signal generating circuit generating a reference clock signal and a predetermined signal which is approximately inversely proportional to a digital data input signal, a delay quantity generating circuit delaying the reference clock signal by a desired phase delay to output a pulse signal, based on the predetermined signal from the signal generating circuit, a delay quantity controller controlling a delay quantity of the delay quantity generating circuit, and a modulated signal generator generating a modulated signal which is pulse-width-modulated based on the pulse signal from the delay quantity generating circuit and the reference clock signal.
Claims26
A pulse width modulation circuit comprising:
- signal generating means for generating a reference clock signal and a predetermined signal which is approximately inversely proportional to a digital data input signal;
- delay quantity generating means for delaying the reference clock signal by a desired phase delay to output a pulse signal, based on the predetermined signal from said signal generating means;
- delay quantity control means for controlling a delay quantity of said delay quantity generating means;
- and
- modulated signal generating means for generating a modulated signal which is pulse-width-modulated based on the pulse signal from said delay quantity generating means and the reference clock signal.
2 more elements
A pulse width modulation circuit comprising:
- a signal generating circuit generating a reference clock signal and a predetermined signal which is approximately inversely proportional to a digital data input signal;
- a delay quantity generating circuit delaying the reference clock signal by a desired phase delay to output a pulse signal, based on the predetermined signal from said signal generating circuit;
- a delay quantity controller controlling a delay quantity of said delay quantity generating circuit;
- and
- a modulated signal generator generating a modulated signal which is pulse-width-modulated based on the pulse signal from said delay quantity generating circuit and the reference clock signal.
2 more elements
A pulse width modulation circuit comprising:
- first signal generating means for generating a high-frequency clock signal synchronized to a reference clock signal by frequency-multiplying the reference signal, and generating a plurality of pulse signals having mutually different phases from the high-frequency clock signal;
- pulse selecting means for selecting one of the plurality of pulse signals based on upper bit data of a digital data input signal which is synchronized to the reference clock signal;
- second signal generating means for generating a predetermined signal which is approximately inversely proportional to lower bit data of the digital data input signal;
- delay quantity generating means for delaying said one of the plurality of pulse signals from said pulse selecting means by a desired phase delay to output a pulse signal, based on the predetermined signal;
- delay quantity control means for controlling a delay quantity of said delay quantity generating means;
- and
- modulated signal generating means for generating a modulated signal which is pulse-width-modulated based on the pulse signal from said delay quantity generating means and said one of the plurality of pulse signals.
4 more elements
A pulse width modulation circuit comprising:
- a first signal generating circuit generating a high-frequency clock signal synchronized to a reference clock signal by frequency-multiplying the reference signal, and generating a plurality of pulse signals having mutually different phases from the high-frequency clock signal;
- a selector selecting one of the plurality of pulse signals based on upper bit data of a digital data input signal which is synchronized to the reference clock signal;
- a second signal generating circuit generating a predetermined signal which is approximately inversely proportional to lower bit data of the digital data input signal;
- a delay quantity generating circuit delaying said one of the plurality of pulse signals from said selector by a desired phase delay to output a pulse signal, based on the predetermined signal;
- a delay quantity controller controlling a delay quantity of said delay quantity generating circuit;
- and
- a modulated signal generator generating a modulated signal which is pulse-width-modulated based on the pulse signal from said delay quantity generating circuit and said one of the plurality of pulse signals.
4 more elements
An optical write unit which drives a light source by an image modulated signal which is pulse-width-modulated based on input digital multi-level image data, and forms an electrostatic latent image by scanning a photoconductor body by scanning means using a scanning light emitted from the light source, said optical write unit comprising:
- a pulse width modulation circuit outputting the image modulated signal;
- and
- a light source driver driving the light source by the image modulated signal output from said pulse width modulation circuit,
- wherein said pulse width modulation circuit comprises:
- a signal generating circuit generating a reference clock signal and a predetermined signal which is approximately inversely proportional to the input digital multi-level image data;
- a delay quantity generating circuit delaying the reference clock signal by a desired phase delay to output a pulse signal, based on the predetermined signal from said signal generating circuit;
- a delay quantity controller controlling a delay quantity of said delay quantity generating circuit;
- and
- a modulated signal generator generating the image modulated signal which is pulse-width-modulated based on the pulse signal from said delay quantity generating circuit and the reference clock signal.
6 more elements
An optical write unit which drives a light source by an image modulated signal which is pulse-width-modulated based on input digital multi-level image data, and forms an electrostatic latent image by scanning a photoconductor body by scanning means using a scanning light emitted from the light source, said optical write unit comprising:
- a pulse width modulation circuit outputting the image modulated signal;
- and
- a light source driver driving the light source by the image modulated signal output from said pulse width modulation circuit,
- wherein said pulse width modulation circuit comprises:
- a first signal generating circuit generating a high-frequency clock signal synchronized to a reference clock signal by frequency-multiplying the reference signal, and generating a plurality of pulse signals having mutually different phases from the high-frequency clock signal;
- a selector selecting one of the plurality of pulse signals based on upper bit data of the input digital multi-level image data which is synchronized to the reference clock signal;
- a second signal generating circuit generating a predetermined signal which is approximately inversely proportional to lower bit data of the input digital multi-level image data;
- a delay quantity generating circuit delaying said one of the plurality of pulse signals from said selector by a desired phase delay to output a pulse signal, based on the predetermined signal;
- a delay quantity controller controlling a delay quantity of said delay quantity generating circuit;
- and
- a modulated signal generator generating the image modulated signal which is pulse-width-modulated based on the pulse signal from said delay quantity generating circuit and said one of the plurality of pulse signals.
8 more elements
An image forming apparatus comprising:
- an optical write unit outputting an image modulated signal which is pulse-width-modulated based on input digital multi-level image data;
- a light source driven by the image modulated signal;
- and
- means for forming an electrostatic latent image by scanning a photoconductor body by scanning means using a scanning light emitted from the light source,
- said optical write unit comprising:
- a pulse width modulation circuit outputting an image modulated signal;
- and
- a light source driver driving the light source by the image modulated signal output from said pulse width modulation circuit,
- wherein said pulse width modulation circuit comprises:
- a signal generating circuit generating a reference clock signal and a predetermined signal which is approximately inversely proportional to the input digital multi-level image data;
- a delay quantity generating circuit delaying the reference clock signal by a desired phase delay to output a pulse signal, based on the predetermined signal from said signal generating circuit;
- a delay quantity controller controlling a delay quantity of said delay quantity generating circuit;
- and
- a modulated signal generator generating the image modulated signal which is pulse-width-modulated based on the pulse signal from said delay quantity generating circuit and the reference clock signal.
11 more elements
An image forming apparatus comprising:
- an optical write unit outputting an image modulated signal which is pulse-width-modulated based on input digital multi-level image data;
- a light source driven by the image modulated signal;
- and
- means for forming an electrostatic latent image by scanning a photoconductor body by scanning means using a scanning light emitted from the light source,
- said optical write unit comprising:
- a pulse width modulation circuit outputting the image modulated signal;
- and
- a light source driver driving the light source by the image modulated signal output from said pulse width modulation circuit,
- wherein said pulse width modulation circuit comprises:
- a first signal generating circuit generating a high-frequency clock signal synchronized to a reference clock signal by frequency-multiplying the reference signal, and generating a plurality of pulse signals having mutually different phases from the high-frequency clock signal;
- a selector selecting one of the plurality of pulse signals based on upper bit data of the input digital multi-level image data which is synchronized to the reference clock signal;
- a second signal generating circuit generating a predetermined signal which is approximately inversely proportional to lower bit data of the input digital multi-level image data;
- a delay quantity generating circuit delaying said one of the plurality of pulse signals from said selector by a desired phase delay to output a pulse signal, based on the predetermined signal;
- a delay quantity controller controlling a delay quantity of said delay quantity generating circuit;
- and
- a modulated signal generator generating the image modulated signal which is pulse-width-modulated based on the pulse signal from said delay quantity generating circuit and said one of the plurality of pulse signals.
13 more elements
An optical write method for an image forming apparatus which drives a light source by an image modulated signal which is pulse-width-modulated based on input digital multi-level image data, and forms an electrostatic latent image by scanning a photoconductor body by scanning means using a scanning light emitted from the light source, said optical write method comprising the steps of:
- (a) outputting the image modulated signal;
- and
- (b) driving the light source by the image modulated signal obtained by said step (a),
- wherein said step (a) includes:
- (a1) generating a reference clock signal and a predetermined signal which is approximately inversely proportional to the input digital multi-level image data;
- (a2) delaying the reference clock signal by a desired phase delay to output a pulse signal, based on the predetermined signal;
- (a3) controlling a delay quantity used in said step (a2);
- and
- (a4) generating the image modulated signal which is pulse-width-modulated based on the pulse signal obtained in said step (a2) and the reference clock signal.
6 more elements
An optical write unit method for an image forming apparatus which drives a light source by an image modulated signal which is pulse-width-modulated based on input digital multi-level image data, and forms an electrostatic latent image by scanning a photoconductor body by scanning means using a scanning light emitted from the light source, said optical write method comprising the steps of:
- (a) outputting the image modulated signal;
- and
- (b) driving the light source by the image modulated signal obtained by said step (a),
- wherein said step (a) includes:
- (a1) generating a high-frequency clock signal synchronized to a reference clock signal by frequency-multiplying the reference signal, and generating a plurality of pulse signals having mutually different phases from the high-frequency clock signal;
- (a2) selecting one of the plurality of pulse signals based on upper bit data of the input digital multi-level image data which is synchronized to the reference clock signal;
- (a3) generating a predetermined signal which is approximately inversely proportional to lower bit data of the input digital multi-level image data;
- (a4) delaying said one of the plurality of pulse signals obtained by said step (a3) by a desired phase delay to output a pulse signal, based on the predetermined signal;
- (a5) controlling a delay quantity used in said step (a4);
- and
- (a6) generating the image modulated signal which is pulse-width-modulated based on the pulse signal obtained by said step (a4) and said one of the plurality of pulse signals.
8 more elements
Dependencies are inferred from the claim text.