EP0421712A2
Expired / Lapsed
EP
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Image forming apparatus, and modulating method therein
Assignee: Canon Inc
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Filing: 1990-10-01
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Granted: —
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Expires: 2010-10-01
Abstract
Abstract A multivalued input recording signal is subjected to pulse-width modulation at a time unit shorter than the period of a clock signal within the period of the recording signal. Alternatively, the multivalued input recording signal is converted into a plurality of different signals each of whose length of time is shorter than a clock signal within the period of the recording signal, thereby performing pulse-width modulation in accordance with a predetermined weighting. This makes it possible to obtain a highly toned recording signal without raising the frequency of the clock signal. Further, density tone data is generated in dependence upon inputted multivalued pixel data, and control is performed using both the irradiation time and emission intensity of a light beam based on the generated density tone data. An image is formed by irradiating a photosensitive body with the controlled light beam.
Inventors
- 👤 Masaki Ojima
- 👤 Masaharu Ohkubo
- 👤 Michio Itoh
- 👤 Hiroshi Sasame
- 👤 Hiromichi Yamada
- 👤 Tetsuo Saito
- 👤 Atsushi Kashihara
- 👤 Takashi Kawana
- 👤 Hiroshi Mano
- 👤 Kaoru Seto
- 👤 Hiroshi Atobe
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 17:53
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40025; H04N1/40043; H04N1/40037; H04N1/405; H04N1/4055; H04N1/4056
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
73 words
An image signal modulating device in a recording apparatus which forms an output image based upon a multivalued input recording signal, comprising: clock generating means for generating a clock signal; converting means for converting the multivalued input recording signal into a plurality of corresponding binary image signals; and output means for outputting the plurality of binary image signals from said converting means in response to the clock signal from said clock generating means.
Claim 2
Dependent Claim
73 words
An image signal modulating device in a recording apparatus which forms an output image based upon a multivalued input recording signal, comprising: clock generating means for generating a clock signal; converting means for converting the multivalued input recording signal into a plurality of corresponding binary image signals; and output means for outputting the plurality of binary image signals from said converting means in response to the clock signal from said clock generating means.
Claim 3
Dependent Claim
24 words
An image signal modulating device according to claim 1, wherein said output means is outputting the plurality of binary image signals of different phase.
Claim 4
Dependent Claim
29 words
An image signal modulating device according to claim 1, wherein said clock generating means generates a plurality of clock signals of the same frequency but of mutually different phase.
Claim 5
Dependent Claim
72 words
An image signal modulating- device in a recording apparatus which forms an output image, comprising: generating means for generating a multivalued image signal; clock generating means for generating a plurality of clock signals; and output means for weighting the multivalued image signal, by a plurality of clock signals generated by said clock generating means, converting the weighted signal into recording image signals having different lengths of time, and outputting these converted signals.
Claim 6
Dependent Claim
72 words
An image signal modulating- device in a recording apparatus which forms an output image, comprising: generating means for generating a multivalued image signal; clock generating means for generating a plurality of clock signals; and output means for weighting the multivalued image signal, by a plurality of clock signals generated by said clock generating means, converting the weighted signal into recording image signals having different lengths of time, and outputting these converted signals.
Claim 7
Dependent Claim
24 words
An image signal modulating device according to claim 4, wherein the plurality of clock signals is the same frequency but of mutually different phase.
Claim 8
Dependent Claim
43 words
An image signal modulating device according to claim 4, wherein the device further comprises: input means for inputting a multivalued input recording signal; and converting means for converting the multivalued input recording signal into the multivalued image signal in accordance with the weighting.
Claim 9
Dependent Claim
112 words
A pulse-width modulating circuit for modulating input digital data into a pulse signal having a corresponding pulse width, comprising: a timing signal generating circuit for generating a timing signal, which has a length of time based upon the digital data, by counting a clock signal having a predetermined frequency; a delay circuit for delaying a timing signal on a front side or rear side of an output of said timing signal generating circuit by a length of time based upon the digital data; and a forming circuit for forming a pulse-width signal by each timing signal of the output of said timing signal generating circuit or the output of said delay circuit.
Claim 10
Dependent Claim
112 words
A pulse-width modulating circuit for modulating input digital data into a pulse signal having a corresponding pulse width, comprising: a timing signal generating circuit for generating a timing signal, which has a length of time based upon the digital data, by counting a clock signal having a predetermined frequency; a delay circuit for delaying a timing signal on a front side or rear side of an output of said timing signal generating circuit by a length of time based upon the digital data; and a forming circuit for forming a pulse-width signal by each timing signal of the output of said timing signal generating circuit or the output of said delay circuit.
Claim 11
Dependent Claim
28 words
The pulse-width modulating circuit according to claim 7, wherein said timing signal generating circuit generates a timing signal based upon most significant n-bit data of the digital data.
Claim 12
Dependent Claim
26 words
The pulse-width modulating circuit according to claim 7, wherein said delay circuit delays a timing signal based upon least significant m-bit data of the digital data.
Claim 13
Dependent Claim
19 words
The pulse-width modulating circuit according to claim 7, wherein said forming circuit comprises a flip-flop circuit or latch circuit.
Claim 14
Dependent Claim
32 words
The pulse-width modulating circuit according to claim 7, wherein said timing signal generating circuit includes a counter circuit, a shift register circuit or a combination of a comparator circuit with these circuits.
Claim 15
Dependent Claim
59 words
The pulse-width modulating circuit according to claim 9, wherein said delay circuit comprises: a delay line circuit for delaying transmission of the timing signal; a decoder circuit for decoding the least significant m-bit data; and a selector circuit for selecting each output signal at a point along said delay line in response to an output from said decoder circuit.
Claim 16
Dependent Claim
122 words
A pulse-width modulating circuit for modulating a multi-bit digital data into a pulse signal having a corresponding pulse width, comprising: a pulse signal generating circuit for generating a pulse signal, which has a length of time based upon most significant bit data of the digital data, by counting a clock signal having a predetermined frequency; a slope forming circuit for forming a trailing edge or a leading edge of the pulse signal from said pulse generating circuit into a slope; a D/A converter circuit for converting a value based upon least significant bit data of the digital data into an analog signal; and a comparator circuit for comparing an output of said D/A converter circuit and output of said slope forming circuit.
Claim 17
Dependent Claim
122 words
A pulse-width modulating circuit for modulating a multi-bit digital data into a pulse signal having a corresponding pulse width, comprising: a pulse signal generating circuit for generating a pulse signal, which has a length of time based upon most significant bit data of the digital data, by counting a clock signal having a predetermined frequency; a slope forming circuit for forming a trailing edge or a leading edge of the pulse signal from said pulse generating circuit into a slope; a D/A converter circuit for converting a value based upon least significant bit data of the digital data into an analog signal; and a comparator circuit for comparing an output of said D/A converter circuit and output of said slope forming circuit.
Claim 18
Dependent Claim
56 words
An image forming apparatus comprising: input means for inputting multivalued pixel data; density generating means for generating density tone data in dependence upon the multivalued pixel data inputted by said input means; and control means for performing control using both a pulse-width and a pulse-height based upon the density tone data from said density generating means.
Claim 19
Dependent Claim
56 words
An image forming apparatus comprising: input means for inputting multivalued pixel data; density generating means for generating density tone data in dependence upon the multivalued pixel data inputted by said input means; and control means for performing control using both a pulse-width and a pulse-height based upon the density tone data from said density generating means.
Claim 20
Dependent Claim
44 words
An image forming apparatus according to claim 14, wherein said control means comprises: modulating means for modulating a light beam based upon the pulse-width and the pulse-height; and irradiating means for irradiating a light-sensitive body with the light beam modulated by said modulating means.
Claim 21
Dependent Claim
49 words
An image forming method comprising the steps of: inputting multivalued pixel data; generating density tone data in dependence upon the multivalued pixel data inputted at said inputting step, and performing control using both a pulse-width and a pulse-height based upon the density tone data generated at said generating step.
Claim 22
Dependent Claim
49 words
An image forming method comprising the steps of: inputting multivalued pixel data; generating density tone data in dependence upon the multivalued pixel data inputted at said inputting step, and performing control using both a pulse-width and a pulse-height based upon the density tone data generated at said generating step.
Claim 23
Dependent Claim
41 words
An image forming method according to claim 16, wherein said control step comprises the steps of: modulating a light beam based upon the pulse-width and the pulse-height; and irradiating a light-sensitive body with the light beam modulated at said modulating step.
Claim 24
Dependent Claim
93 words
An image signal modulating method in a recording apparatus which forms an output image based upon a multivalued input recording signal, comprising the steps of: generating a clock signal; converting the multivalued input recording signal into a plurality of corresponding binary image signals; and outputting the plurality of binary image signals generated at said converting step within one period of the multivalued input recording signal in response to the clock signal generated at said clock generating step; and performing pulse-width modulation at a time unit shorter than the period of the clock signal.
Claim 25
Dependent Claim
93 words
An image signal modulating method in a recording apparatus which forms an output image based upon a multivalued input recording signal, comprising the steps of: generating a clock signal; converting the multivalued input recording signal into a plurality of corresponding binary image signals; and outputting the plurality of binary image signals generated at said converting step within one period of the multivalued input recording signal in response to the clock signal generated at said clock generating step; and performing pulse-width modulation at a time unit shorter than the period of the clock signal.
Claim 26
Dependent Claim
67 words
An image signal modulating method in a recording apparatus which forms an output image, comprising the steps of: generating the image signal; generating a plurality of clock signals; and weighting the image signal by a plurality of clock signals generated at said clock generating step, converting the weighted signals into recording image signals having different lengths of time, and outputting these converted signals; pulse-width modulation being performed.
Claim 27
Dependent Claim
67 words
An image signal modulating method in a recording apparatus which forms an output image, comprising the steps of: generating the image signal; generating a plurality of clock signals; and weighting the image signal by a plurality of clock signals generated at said clock generating step, converting the weighted signals into recording image signals having different lengths of time, and outputting these converted signals; pulse-width modulation being performed.
Claim 28
Dependent Claim
71 words
A pulse-width-modulation circuit having a system clock and delay means which provides a plurality of signals having delays relative to each other of less than a period of the system clock, the timing of the said signals determining the timing of a pulse edge of a pulse-width-modulated output signal whereby the pulse width of the output signal may be varied by an amount shorter than a period of the system clock.
Claim 29
Dependent Claim
71 words
A pulse-width-modulation circuit having a system clock and delay means which provides a plurality of signals having delays relative to each other of less than a period of the system clock, the timing of the said signals determining the timing of a pulse edge of a pulse-width-modulated output signal whereby the pulse width of the output signal may be varied by an amount shorter than a period of the system clock.
Claim 30
Dependent Claim
62 words
A pulse-width-modulation circuit having a clock and a first means to generate a pulse having a length in accordance with input data which length is a whole number of periods of the clock, and a second means to vary the length of the pulse in accordance with input data by an amount other than a whole number of periods of the clock.
Claim 31
Dependent Claim
62 words
A pulse-width-modulation circuit having a clock and a first means to generate a pulse having a length in accordance with input data which length is a whole number of periods of the clock, and a second means to vary the length of the pulse in accordance with input data by an amount other than a whole number of periods of the clock.
Claim 32
Dependent Claim
71 words
Image forming apparatus for forming variable images in which an image forming signal is applied to an image forming means to effect image formation, the timing of the image forming signal being varied in accordance with input data to enable variable tone imges to be formed, and the level of the image forming signal also being varied in accordance with input data to further enable variable tone images to be formed.
Claim 33
Dependent Claim
71 words
Image forming apparatus for forming variable images in which an image forming signal is applied to an image forming means to effect image formation, the timing of the image forming signal being varied in accordance with input data to enable variable tone imges to be formed, and the level of the image forming signal also being varied in accordance with input data to further enable variable tone images to be formed.
Claim 34
Dependent Claim
16 words
Apparatus according to claim 22 in which the image forming signal is a light beam signal.
Claim 35
Dependent Claim
27 words
Apparatus according to claim 22 or claim 23 in which timing of the image forming signal is varied by one of pulse-width-modulation, error diffusion and dither processing.
References Cited (Backward Citations)
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