US3560757A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for generating block-printer signal in color printing apparatus
Assignee: Crosfield Electronics Ltd
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Filing: 1969-07-18
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Granted: 1971-02-02
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Expires: 1989-07-18
Abstract
Abstract In color printing, a circuit for generating a black printer signal has means for varying a selectivity factor which permits adjustment of the amount of black in colored areas while leaving it substantially unchanged in neutral areas. This variation is accomplished without substantial alteration of the scale factor of the black printer signal. The circuit includes maximum and minimum signal selector circuits receiving the color component signals and supplying the maximum and minimum signals to the two inputs of a differential amplifier having a feedback path to a first of the two inputs. The selectivity factor depends on the ratio of resistances in the feedback path and in the first input path.
Inventors
- 👤 Peter C Pugsley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:11
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/46; H04N1/56; H04N1/60; H04N1/6016
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
163 words
Apparatus for reproducing an image in colour and having means for scanning, element by element, an original or a set of colour separations obtained from the original to derive electric signals representing variations of different colour components of the original and a circuit responsive to the said signals to generate a black printer signal, the circuit comprising maximum and minimum signal-selector circuits each connected to receive the said colour-component electric signals; a differential amplifier having its noninverting input connected to the minimum signalselector circuit to receive the minimum colour-component signal and having its inverting input connected through a first resistance to the maximum signal-selector circuit to receive the maximum colour-component signal; and a feedback path including a feedback resistance between the output of the differential amplifier and the junction of the first resistance and the said inverting input, whereby adjustment of the ratio of the said resistances varies the black-printer selectivity factor without substantially altering the scale factor of the black printer signal.
Claim 2
Dependent Claim
163 words
Apparatus for reproducing an image in colour and having means for scanning, element by element, an original or a set of colour separations obtained from the original to derive electric signals representing variations of different colour components of the original and a circuit responsive to the said signals to generate a black printer signal, the circuit comprising maximum and minimum signal-selector circuits each connected to receive the said colour-component electric signals; a differential amplifier having its noninverting input connected to the minimum signalselector circuit to receive the minimum colour-component signal and having its inverting input connected through a first resistance to the maximum signal-selector circuit to receive the maximum colour-component signal; and a feedback path including a feedback resistance between the output of the differential amplifier and the junction of the first resistance and the said inverting input, whereby adjustment of the ratio of the said resistances varies the black-printer selectivity factor without substantially altering the scale factor of the black printer signal.
Claim 3
Dependent Claim
81 words
Apparatus in accordance with claim 1, in which the outputs of the maximum and minimum selector circuits are respectively connected to individual voltage dividers, a tapping on the divider associated with the minimum signal being connected to the noninverting input of the differential amplifier and a corresponding tapping on the divider associated with the maximum signal being connected through the said first resistance to the inverting input of the differential amplifier, the noninverting input being also connected to an amplifier-balancing potentiometer.
Claim 4
Dependent Claim
68 words
Apparatus in accordance with claim 2, in which a voltage divider is connected across the differential amplifier output and the feedback signal is derived from a tapping on the voltage divider such that the fraction of the output voltage applied to the feedback circuit is the same as the fraction of the maximum and minimum colour signals obtained from the voltage dividers to which these signals are applied.
Claim 5
Dependent Claim
31 words
Apparatus in accordance with claim 3, in which the tapping on the voltage divider in the output circuit is additionally connected to gain-setting potentiometer connected across the output of the amplifier.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-01 | 1974-08-03 | 1975-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-01 | 1978-08-03 | 1979-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-01 | 1982-08-03 | 1983-02-02 | $7700.00 | Window Closed / Lapsed |