Patent US416095A successfully refreshed from Google Patents.
Patent EP0216462A2 successfully refreshed from Google Patents.
EP0216462A2
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An apparatus for generating an image from a digital video signal
Assignee: Canon Inc
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Filing: 1986-07-22
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Granted: —
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Expires: 2006-07-22
Abstract
Abstract An apparatus for generating a high quality image from a digital video signal includes a system for gamma correcting the digital video signal with a digital look up table (9) and for converting (with 2) the resultant digital signal to an analog video signal. Another circuit (3) generates a triangular wave reference pattern signal and a comparator (4) compares the analog video signal with the triangular wave reference pattern signal to form a pulse-width-modulated signal. A raster scanning print engine (8) producing, for example, a laser beam. scans over a recording medium in accordance with the pulse-width-modulated signal, thereby forming an image of high quality on the recording medium of a print engine. This apparatus can also be used with an analog video signal by first converting the analog video signal to a digital video signal with an analog to digital converter.
Inventors
- 👤 John Hugh Riseman
- 👤 John Jacobs Smith
- 👤 Alice Marie D'entremont
- 👤 Craig Edward Goldman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 10:33
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/407; H04N1/405; H04N1/4055; H04N1/4056
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
103 words
An image processing apparatus responsive to a digital input signal, said apparatus comprising: a raster scanning print engine for generating a series of successive scan lines; means for generating a pulse-width-modulated signal from a digital input signal input to said apparatus; and means for applying said pulse-width-modulated signal to said print engine to cause said print engine to generate each said scan line as a succession of line-segments, the lengths of which are controlled in accordance with said pulse-width-modulated signal to produce a variable density line screen from said line segments, said line screen comprising a plurality of columns of said line segments.
Claim 2
Dependent Claim
103 words
An image processing apparatus responsive to a digital input signal, said apparatus comprising: a raster scanning print engine for generating a series of successive scan lines; means for generating a pulse-width-modulated signal from a digital input signal input to said apparatus; and means for applying said pulse-width-modulated signal to said print engine to cause said print engine to generate each said scan line as a succession of line-segments, the lengths of which are controlled in accordance with said pulse-width-modulated signal to produce a variable density line screen from said line segments, said line screen comprising a plurality of columns of said line segments.
Claim 3
Dependent Claim
67 words
An apparatus according to claim 1, wherein said generating means includes converting means for converting said digital input signal to an analog video signal, reference pattern signal generating means for generating an analog reference pattern signal of predetermined period, and comparing means for comparing said converted analog video signal with said analog reference pattern signal and for generating said pulse-width-modulated signal on the basis of said comparison.
Claim 4
Dependent Claim
27 words
An image processing apparatus according to claim 1 or 2, wherein the axes of said columns comprising said line screen are substantially perpendicular to said scan lines.
Claim 5
Dependent Claim
29 words
An image processing apparatus according to claim 1 or 2, wherein the axes of said columns comprising said line screen extend at an oblique angle to said scan lines.
Claim 6
Dependent Claim
146 words
An image processing apparatus for forming an image on a recording medium, said apparatus comprising: video signal output means for generating an analog video signal; pattern signal generating means for producing a pattern signal of predetermined period; a pulse-width-modulated signal output means for generating a pulse-width modulated signal in accordance with the analog video signal generated by said video signal output means and said pattern signal generated by said pattern signal generating means; and image forming means for scanning lines on a recording medium with a beam in accordance with said - pulse-width-modulated signal generated by said pulse-width-modulated signal generating means thereby forming an image on said recording medium; said image forming means including means for generating a synchronizing signal for each line scanned on the recording medium, said pattern signal generating means generating the pattern signal of predetermined period in accordance with said synchronizing signal.
Claim 7
Dependent Claim
146 words
An image processing apparatus for forming an image on a recording medium, said apparatus comprising: video signal output means for generating an analog video signal; pattern signal generating means for producing a pattern signal of predetermined period; a pulse-width-modulated signal output means for generating a pulse-width modulated signal in accordance with the analog video signal generated by said video signal output means and said pattern signal generated by said pattern signal generating means; and image forming means for scanning lines on a recording medium with a beam in accordance with said - pulse-width-modulated signal generated by said pulse-width-modulated signal generating means thereby forming an image on said recording medium; said image forming means including means for generating a synchronizing signal for each line scanned on the recording medium, said pattern signal generating means generating the pattern signal of predetermined period in accordance with said synchronizing signal.
Claim 8
Dependent Claim
102 words
An image processing apparatus comprising: digital video signal generating means for generating a digital video signal having a characteristic; characteristic converting means for converting the characteristic of said digital video signal generated by said digital video signal generating means and for producing a converted digital video signal therefrom; digital-to-analog converting means for converting the converted digital video signal generated by said characteristic converting means into an analog video signal; pattern signal generating means for generating a pattern signal of predetermined period; and pulse-width-modulated signal generating means for generating a pulse-width-modulated signal in accordance with said analog video signal and said pattern signal.
Claim 9
Dependent Claim
102 words
An image processing apparatus comprising: digital video signal generating means for generating a digital video signal having a characteristic; characteristic converting means for converting the characteristic of said digital video signal generated by said digital video signal generating means and for producing a converted digital video signal therefrom; digital-to-analog converting means for converting the converted digital video signal generated by said characteristic converting means into an analog video signal; pattern signal generating means for generating a pattern signal of predetermined period; and pulse-width-modulated signal generating means for generating a pulse-width-modulated signal in accordance with said analog video signal and said pattern signal.
Claim 10
Dependent Claim
75 words
An apparatus according to claim 6, further comprising image forming means for scanning successive lines on a recording medium with a beam in accordance with said pulse-width-modulated signal generated by said pulse-width-modulated signal generating means thereby forming an image on said recording medium, and wherein said characteristic converting means includes means for changing the factor converting the characteristic of said digital video signal for each of the successive lines scanned by said image forming means.
Claim 11
Dependent Claim
31 words
An apparatus according to claim 6 or 7, wherein said characteristic converting means comprises storage means containing digital information for providing at least one non-linear transformation of said digital video signal.
Claim 12
Dependent Claim
24 words
An apparatus according to claim 8, wherein said storage means comprises a read only memory for storing a digital lock-up table for gamma correction.
Claim 13
Independent Claim
198 words
An apparatus for generating an image from a digital video signal comprising: A. a raster scanning print engine for generating a series of successive scanning lines; B. a digital look up table addressable by said digital video signal; C. means for generating from said digital video signal a pulse-width-modulated signal, said pulse-width-modulated signal generating means comprising: (1) means for applying said digital video signal as an address to said digital look up table for producing in accordance with said digital look up table a resultant gamma corrected digital signal; (2) means for converting said resultant gamma corrected digital signal to an analog video signal; (3) means for generating a periodic analog reference signal of predetermined period; and (4) means for comparing said analog video signal to said periodic analog reference signal thereby to produce said pulse-width- modulated signal; and D. means for applying said pulse-width-modulated signal to-said print engine for generating each said scanning line as a succession of line-segments, the length of which are controlled in accordance with said pulse-width-modulated signal to produce a variable density line screen from said line segments, an axis of symmetry of the line screen being substantially normal to the scanning lines.
Claim 14
Independent Claim
198 words
An apparatus for generating an image from a digital video signal comprising: A. a raster scanning print engine for generating a series of successive scanning lines; B. a digital look up table addressable by said digital video signal; C. means for generating from said digital video signal a pulse-width-modulated signal, said pulse-width-modulated signal generating means comprising: (1) means for applying said digital video signal as an address to said digital look up table for producing in accordance with said digital look up table a resultant gamma corrected digital signal; (2) means for converting said resultant gamma corrected digital signal to an analog video signal; (3) means for generating a periodic analog reference signal of predetermined period; and (4) means for comparing said analog video signal to said periodic analog reference signal thereby to produce said pulse-width- modulated signal; and D. means for applying said pulse-width-modulated signal to-said print engine for generating each said scanning line as a succession of line-segments, the length of which are controlled in accordance with said pulse-width-modulated signal to produce a variable density line screen from said line segments, an axis of symmetry of the line screen being substantially normal to the scanning lines.
Claim 15
Dependent Claim
71 words
An image processing apparatus responsive to a digital video signal input thereto, said apparatus comprising: a digital-to-analog converting means for converting the digital video signal input to said apparatus into an analog video signal; a pattern signal generating means for generating a pattern signal of a predetermined period; and a pulse-width-modulated signal generating means for generating a pulse-width-modulated signal in accordance with said converted analog video signal and said pattern signal.
Claim 16
Dependent Claim
71 words
An image processing apparatus responsive to a digital video signal input thereto, said apparatus comprising: a digital-to-analog converting means for converting the digital video signal input to said apparatus into an analog video signal; a pattern signal generating means for generating a pattern signal of a predetermined period; and a pulse-width-modulated signal generating means for generating a pulse-width-modulated signal in accordance with said converted analog video signal and said pattern signal.
Claim 17
Independent Claim
54 words
An apparatus according to any of claims 1 to 4, and 6 to 10, wherein said digital input or video signal ranges between maximum and minimum values and wherein said pulse-width-modulated signal generating means generates a pulse-width-modulated signal having a predetermined pulse width when said digital input or video signal has the minimum value.
Claim 18
Independent Claim
54 words
An apparatus according to any of claims 1 to 4 and 6 to 10, wherein said digital input or video signal ranges between maximum and minimum values and wherein said pulse-width-modulated signal generating means generates a pulse-width-modulated signal having a predetermined pulse width when said digital input or video signal has the maximum value.
Claim 19
Independent Claim
30 words
An apparatus according to any of claims 5 to 11, wherein said generating means generates as said pattern signal or analog reference signal a triangular wave signal of predetermined period.
Claim 20
Independent Claim
52 words
An apparatus according to any of claims 5 to 11 or 14, further comprising reference clock generating means for generating a reference clock, said pattern signal or analog reference signal generating means producing a clock for generating said pattern signal or analog reference signal by dividing the frequency of said reference clock.
Claim 21
Dependent Claim
37 words
1 6. An apparatus according to any of claims 5 to 10, wherein said pattern signal or analog reference signal generating means includes means for adjusting at least one of the amplitude and offset of that signal.
References Cited (Backward Citations)
US3916096A
Cited
US4040094A
Cited
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