US3769455A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for making half-tone screen printing cylinders
Assignee: Werkspoor Amsterdam NV
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Filing: 1972-03-01
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Granted: 1973-10-30
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Expires: 1992-03-01
Abstract
Abstract The depth of penetration of the electromagnetically driven engraving element of an engraving machine into the material to be engraved is regulated by controlling the electromagnetic driving system of the engraving element with the aid of alternating current and of direct current. The value of the direct current and also the amplitude of the alternating current are varied in dependence on the measured grey value of the required engraving and the engraving element is spring biased in the direction to penetrate into the cylinder being engraved. The alternating and direct current signals are combined to produce a combined signal in which the amplitude excursions opposing the biasing spring are clamped to a selected level at which the winding of the engraving assembly is saturated. The frequency of the ac signal is greater than the resonant frequency of the engraving assembly and the sum of the displacements of the engraving element in opposition to the biasing spring, which displacements are due respectively to the dc signal and to the ac signal, is a constant. The movement of the engraving element is in phase opposition to the current through the engraving assembly winding and the winding current effects saturation thereof at the point of maximum penetration by the engraving element.
Inventors
- 👤 Vos F De
- 👤 Steege J Ter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 06:50
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40025; G; G05; G05B; G05B2219/00; G05B2219/30; G05B2219/45; G05B2219/45212; G05B2219/49; G05B2219/49235
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
169 words
In a system for producing half-tone screen printing cylinders, in combination: a master cylinder having an image thereon; a printing cylinder upon which the image on said master cylinder is to be engraved; means for circumferentially scanning said master cylinder to produce a dc signal which varies directly in amplitude according to the intensity of the image on said master cylinder; an engraving assembly associated with said printing cylinder and including an engraving member, spring means for urging the engraving member into the printing cylinder and inductive winding means for opposing said spring means normally to retract said engraving member out of the printing cylinder; means for producing an ac signal at a frequency related to circumferential scanning and varying in amplitude inversely with respect to the intensity of the image on said master cylinder; means for combining said ac signal and said dc signal and for energizing said winding means such that amplitude excursions of the combined signal opposing said spring means are clamped to a selected value.
Claim 2
Dependent Claim
169 words
In a system for producing half-tone screen printing cylinders, in combination: a master cylinder having an image thereon; a printing cylinder upon which the image on said master cylinder is to be engraved; means for circumferentially scanning said master cylinder to produce a dc signal which varies directly in amplitude according to the intensity of the image on said master cylinder; an engraving assembly associated with said printing cylinder and including an engraving member, spring means for urging the engraving member into the printing cylinder and inductive winding means for opposing said spring means normally to retract said engraving member out of the printing cylinder; means for producing an ac signal at a frequency related to circumferential scanning and varying in amplitude inversely with respect to the intensity of the image on said master cylinder; means for combining said ac signal and said dc signal and for energizing said winding means such that amplitude excursions of the combined signal opposing said spring means are clamped to a selected value.
Claim 3
Dependent Claim
25 words
In a system as defined in claim 1 wherein the frequency of said ac signal is greater than the resonant frequency of said engraving assembly.
Claim 4
Dependent Claim
31 words
In a system as defined in claim 2 wherein said means for combining includes a differential amplifier having said combined signal and the current through said winding means as inputs thereto.
Claim 5
Dependent Claim
25 words
In a system as defined in claim 3 including an amplifier driving said winding means and having the output of said differential amplifier connected thereto.
Claim 6
Dependent Claim
182 words
In a system for producing half-tone screen printing cylinders, in combination: a master cylinder having an image thereon; a printing cylinder upon which the image on said master cylinder is to be engraved; means for circumferentially scanning said master cylinder to produce an ac signal which varies directly in amplitude according to the intensity of the image on said master cylinder; an engraving assembly associated with said printing cylinder and including an engraving member, spring means for urging said engraving member into said printing cylinder, and inductive winding means for opposing said spring means normally to retract said engraving member out of the printing cylinder; means for producing an ac signal at a frequency related to circumferential scanning and varying in amplitude inversely with respect to the intensity of the image on said master cylinder; means for combining said ac signal and said dc signal and for energizing said winding means so that the sum of the displacements of said engraving member in opposition to said spring means due respectively to said dc signal and to said ac signal is a constant.
Claim 7
Dependent Claim
182 words
In a system for producing half-tone screen printing cylinders, in combination: a master cylinder having an image thereon; a printing cylinder upon which the image on said master cylinder is to be engraved; means for circumferentially scanning said master cylinder to produce an ac signal which varies directly in amplitude according to the intensity of the image on said master cylinder; an engraving assembly associated with said printing cylinder and including an engraving member, spring means for urging said engraving member into said printing cylinder, and inductive winding means for opposing said spring means normally to retract said engraving member out of the printing cylinder; means for producing an ac signal at a frequency related to circumferential scanning and varying in amplitude inversely with respect to the intensity of the image on said master cylinder; means for combining said ac signal and said dc signal and for energizing said winding means so that the sum of the displacements of said engraving member in opposition to said spring means due respectively to said dc signal and to said ac signal is a constant.
Claim 8
Dependent Claim
25 words
A system as defined in claim 5 wherein said means for combining includes a differential amplifier having said dc and ac signals as inputs thereto.
Claim 9
Dependent Claim
40 words
In a system as defined in claim 5 wherein the displacement of the engraving member in opposition to said spring-biasing due to dc current alone is equal to the displacement in the same sense due to ac current amplitude alone.
Claim 10
Dependent Claim
257 words
In a system for producing half-tone screen printing cylinders, in combination: a master cylinder having an image thereon; a printing cylinder upon which the image on said master cylinder is to be engraved; means for circumferentially scanning said master cylinder to produce a dc signal which varies stepwise in decreasing amplitude steps in accord with discrete levels of intensity of the image on said master cylinder as such levels progress from light to dark; an engraving assembly associated with said printing cylinder and including an engraving member, spring means for urging the engraving member into the printing cylinder, and inductive winding means for opposing said spring means to retract said engraving member out of the printing cylinder, said engraving assembly having a fixed natural frequency of oscillation; means for producing an ac signal at a selected frequency related to said natural frequency of the engraving assembly and of variable amplitude which increases according to the level of intensity of said image on the master cylinder as such intensity progresses from light to dark; means for combining said dc signal and said ac signal and for energizing said winding means with such combined signal; and the frequency of said ac signal being sufficiently different from the natural frequency of said engraving assembly so that the sum of the displacements of said engraving member in opposition to said spring means due respectively to said dc signal and to said ac signal is a constant for each of said discrete levels of intensity of said image on the master cylinder.
Claim 11
Dependent Claim
257 words
In a system for producing half-tone screen printing cylinders, in combination: a master cylinder having an image thereon; a printing cylinder upon which the image on said master cylinder is to be engraved; means for circumferentially scanning said master cylinder to produce a dc signal which varies stepwise in decreasing amplitude steps in accord with discrete levels of intensity of the image on said master cylinder as such levels progress from light to dark; an engraving assembly associated with said printing cylinder and including an engraving member, spring means for urging the engraving member into the printing cylinder, and inductive winding means for opposing said spring means to retract said engraving member out of the printing cylinder, said engraving assembly having a fixed natural frequency of oscillation; means for producing an ac signal at a selected frequency related to said natural frequency of the engraving assembly and of variable amplitude which increases according to the level of intensity of said image on the master cylinder as such intensity progresses from light to dark; means for combining said dc signal and said ac signal and for energizing said winding means with such combined signal; and the frequency of said ac signal being sufficiently different from the natural frequency of said engraving assembly so that the sum of the displacements of said engraving member in opposition to said spring means due respectively to said dc signal and to said ac signal is a constant for each of said discrete levels of intensity of said image on the master cylinder.
Claim 12
Dependent Claim
43 words
In a system as defined in claim 8 wherein the displacements of said engraving member due respectively to said dc signal and to said ac signal are substantially equal for each of said levels of intensity of said image on the master cylinder.
Claim 13
Dependent Claim
31 words
In a system as defined in claim 9 wherein the frequency of said ac signal is substantially Square Root 2 f where f is the natural frequency of said engraving assembly.
Claim 14
Independent Claim
170 words
The method of producing a half-tone screen printing cylinder which comprises the steps of: a. rotating a screen printing cylinder at a uniform speed while periodically electro-mechanically engraving the cylinder at a frequency f which is about Square Root 2 times the natural resonant frequency of the assembly used for engraving; b. generating dc signals at said frequency f whose amplitudes vary stepwise in decreasing amplitude in accord with discrete levels of intensity of an image to be produced as such levels progress from light to dark; c. generating an ac signal at said frequency f and of variable amplitude which increases according to said levels of intensity as such levels of intensity progress from light to dark; d. combining the dc and ac signals of steps (b) and (c) such that displacements of the engraving assembly due respectively to the dc and ac components of the combined signal are substantially equal for all levels of intensity; and e. energizing the engraving assembly with the combined signal of step (d).
Claim 15
Independent Claim
170 words
The method of producing a half-tone screen printing cylinder which comprises the steps of: a. rotating a screen printing cylinder at a uniform speed while periodically electro-mechanically engraving the cylinder at a frequency f which is about Square Root 2 times the natural resonant frequency of the assembly used for engraving; b. generating dc signals at said frequency f whose amplitudes vary stepwise in decreasing amplitude in accord with discrete levels of intensity of an image to be produced as such levels progress from light to dark; c. generating an ac signal at said frequency f and of variable amplitude which increases according to said levels of intensity as such levels of intensity progress from light to dark; d. combining the dc and ac signals of steps (b) and (c) such that displacements of the engraving assembly due respectively to the dc and ac components of the combined signal are substantially equal for all levels of intensity; and e. energizing the engraving assembly with the combined signal of step (d).
Claim 16
Dependent Claim
18 words
The method according to claim 11 including the step of constantly spring-biasing the engraving element toward the cylinder.
Claim 17
Dependent Claim
25 words
The method according to claim 12 wherein the ac component of the driving current is substantially in phase opposition to movement of the engraving member.
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) | 1976-10-29 | 1977-04-30 | 1977-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-29 | 1981-04-30 | 1981-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-29 | 1985-04-30 | 1985-10-30 | $7700.00 | Window Closed / Lapsed |