Patent US3790875A successfully refreshed from Google Patents.
US3790875A
Expired / Lapsed
US
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Digital to analogue converter
Assignee: Autoflow Engineering Ltd
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Filing: 1971-11-24
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Granted: 1974-02-05
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Expires: 1991-11-24
Abstract
Abstract A lens generating machine is provided with electrical digital to analogue converters for controlling various functions of the machine, the converters each including a specially-wound transformer provided on a secondary winding thereof with tapping points corresponding to digital control instructions concerning various lens optical parameters associated with said machine functions, operation of the machine being controlled through switch means for selectively effecting connection to said tappings to make available voltages which are the analogue equivalents of the corresponding control instructions and which are utilised to effect the necessary machine functions to produce a lens with the desired optical characteristics, for example, a toric lens.
Inventors
- 👤 R Craxton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 07:52
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/188; B; B24; B24B; B24B13/00; B24B13/04; B24B13/043; G05B2219/00; G05B2219/30; G05B2219/33; G05B2219/33268; G05B2219/41; G05B2219/41477; H; H03; H03M; H03M1/00; H03M1/12; H03M1/48
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
169 words
A lens generating machine for generating lenses with desired parameters including front and rear lens surface radii of curvature and lens thickness, which machine comprises support means for supporting a lens upon whose surface a desired curvature is to be generated, a cutter for generating said surface curvature, positioning means for relatively positioning said cutter and lens in accordance with discrete electrical operating signals which are linearly related to predetermined lens parameters, converter means for receiving discrete control instructions non-linearly related to said predetermined parameters and converting said instructions into said discrete electrical operating signals whereby to effect appropriate operation of said positioning means to produce desired values of lens parameters, said converter comprising a transformer with a primary winding for connection to an alternating current supply, a secondary winding provided with a plurality of non-linearly spaced tappings corresponding to discrete control instructions relating to a lens parameter, switch means for selectively effecting connection to said tappings whereby to make available an electrical operating signal to said positioning means.
Claim 2
Dependent Claim
169 words
A lens generating machine for generating lenses with desired parameters including front and rear lens surface radii of curvature and lens thickness, which machine comprises support means for supporting a lens upon whose surface a desired curvature is to be generated, a cutter for generating said surface curvature, positioning means for relatively positioning said cutter and lens in accordance with discrete electrical operating signals which are linearly related to predetermined lens parameters, converter means for receiving discrete control instructions non-linearly related to said predetermined parameters and converting said instructions into said discrete electrical operating signals whereby to effect appropriate operation of said positioning means to produce desired values of lens parameters, said converter comprising a transformer with a primary winding for connection to an alternating current supply, a secondary winding provided with a plurality of non-linearly spaced tappings corresponding to discrete control instructions relating to a lens parameter, switch means for selectively effecting connection to said tappings whereby to make available an electrical operating signal to said positioning means.
Claim 3
Dependent Claim
20 words
A machine, as claimed in claim 1, wherein there is provided a transformer and associated switch means for each parameter.
Claim 4
Dependent Claim
76 words
A machine, as claimed in claim 1, wherein said positioning means includes means responsive to the actual value of the parameter, comparator means for producing an electrical operating signal proportional to the difference between the desired value of the parameter, as represented by an electrical signal associated with the appropriate control instruction, and an electrical signal representing the actual value of the machine function, which operating signal is fed as an input to the positioning means.
Claim 5
Dependent Claim
15 words
A machine, as claimed in claIm 3, wherein the comparator means includes an operational amplifier.
Claim 6
Dependent Claim
50 words
A machine as claimed in claim 1, wherein there is provided for a parameter one or more additional transformers and associated switch means arranged to provide interpolation between the adjacent switch positions of the preceding transformers and thereby enable more precise control instructions to be converted into electrical operating signals.
Claim 7
Dependent Claim
39 words
A machine, as claimed in claim 1, wherein the switch means for each transformer comprises a plurality of relays with contacts connected to separate tappings of the transformer secondary winding and selectively operable by a common relay selector means.
Claim 8
Dependent Claim
66 words
A machine, as claimed in claim 1, wherein compensation means are provided to compensate for computational errors associated with the conversion of control instructions in order to produce the required overall lens characteristics, said compensation means being arranged to apply an electrical signal of appropriate polarity to the output of the converter whereby to effect an appropriate correction in the parameter set by the positioning means.
Claim 9
Dependent Claim
46 words
A machine, as claimed in claim 1, wherein compensation means are provided for interconnecting converter circuitry associated with two or more parameters which have a geometrical interaction upon the overall lens characteristics in such a manner as to simulate said interaction in terms of electrical signals.
Claim 10
Dependent Claim
55 words
A machine, as claimed in claim 1, wherein the lens generating machine is arranged for the production of toric lenses and said parameters comprise the two radii of curvature of the lens face, the lens thickness and the curvature of the lens back in order to achieve a lens of the required overall optical power.
References Cited (Backward Citations)
US3066868A
Cited
US3136933A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-04 | 1977-08-06 | 1978-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-04 | 1981-08-06 | 1982-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-04 | 1985-08-06 | 1986-02-05 | $7700.00 | Window Closed / Lapsed |