EP0170484A2
Expired / Lapsed
EP
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Elapsed time indicator
Assignee: Johnson Matthey PLC
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Filing: 1985-07-23
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Granted: —
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Expires: 2005-07-23
Abstract
Abstract An apparatus for indicating the lapse of a predetermined time period compises an indicator element (7), which changes from a first state to a second state when an electrical potential difference is applied to it and reverts to the first state when the potential difference falls below a given value, In combination with a circuit with a bleed resistor (9) for controlling as a function of time a potential difference, applied to the indicator element (7). A cell (1) may apply the potential difference. After a certain period of time the cell (1) will be effectively discharged through the bleed resistor (9), the potential difference applied to the indicator element (7) will fall causing it to change state and sign (8) will then be visible. This indicates the end of the time period.
Inventors
- 👤 Robin Andras Benedek
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-10 00:47
CPC Classifications
G; G04; G04F; G04F1/00; G04F1/005
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
91 words
An electrically operated apparatus for indicating the lapse of a predetermined time period, the apparatus comprising an indicator element which is changeable from a first state to a second state when an electrical potential difference greater than a specified value is applied thereto and is automatically revertable to the first state when the electrical potential difference applied to the element is equal to or less that the specified value, in combination with a circuit with means for controlling as a function of time a potential difference, applied to the indicator element.
Claim 2
Dependent Claim
91 words
An electrically operated apparatus for indicating the lapse of a predetermined time period, the apparatus comprising an indicator element which is changeable from a first state to a second state when an electrical potential difference greater than a specified value is applied thereto and is automatically revertable to the first state when the electrical potential difference applied to the element is equal to or less that the specified value, in combination with a circuit with means for controlling as a function of time a potential difference, applied to the indicator element.
Claim 3
Dependent Claim
34 words
An apparatus according to claim 1 wherein a current flows in the circuit and the applied potential difference is controlled as a function of time by means for controlling the magnitude of the current.
Claim 4
Dependent Claim
20 words
An apparatus according to claim 2 wherein the means for controlling the magnitude of the current is a bleed resistor.
Claim 5
Independent Claim
15 words
An apparatus according to any preceding claim wherein the indicator element is an optical shutter.
Claim 6
Dependent Claim
9 words
An apparatus according to claim 4 wherein the optical
Claim 7
Dependent Claim
17 words
An apparatus according to claim 4 wherein the optical shutter is a sheet of liquid crystal material.
Claim 8
Independent Claim
58 words
An apparatus according to any preceding claim wherein the circuit further includes a sensor for sensing a physical condition and a latch circuit, such that the latch circuit is operable by the sensor to decrease the potential difference and cause the indicator element to revert to the first state before the end of the predetermined period of time.
Claim 9
Independent Claim
27 words
An apparatus according to any preceding claim wherein the potential difference applied to the indicator element is provided by a source of electric current of known capacity.
Claim 10
Dependent Claim
21 words
An apparatus according to claim 7 wherein the source of electric current of known capacity is at least one electric cell.
Claim 11
Dependent Claim
14 words
An apparatus according to claim 8 wherein the cell is a silver oxide cell.
Claim 12
Independent Claim
80 words
A method for indicating the lapse of a predetermined time period comprising applying a potential difference to an indicator element which is changeable from a first state to a second state when an electrical potential difference greater than a specified value is applied thereto and is automatically revertable to the first state when the electrical potential difference applied to the element is equal to or less that the specified value, the potential difference being controlled as a function of time.
Claim 13
Independent Claim
80 words
A method for indicating the lapse of a predetermined time period comprising applying a potential difference to an indicator element which is changeable from a first state to a second state when an electrical potential difference greater than a specified value is applied thereto and is automatically revertable to the first state when the electrical potential difference applied to the element is equal to or less that the specified value, the potential difference being controlled as a function of time.
Claim 14
Dependent Claim
65 words
Dear Sirs, Re: New European Patent Application Johnson Matthey Public Limited Company. The application was filed on 23rd July 1985 and we regret that we have noticed an error on page 4 line 13 where "is" should read "may be". Given the priority year has not yet expired we enclose an amended page 4 in triplicate for insertion into the specification as filed. Yours Respectfully,
Claim 15
Dependent Claim
65 words
Dear Sirs, Re: New European Patent Application Johnson Matthey Public Limited Company. The application was filed on 23rd July 1985 and we regret that we have noticed an error on page 4 line 13 where "is" should read "may be". Given the priority year has not yet expired we enclose an amended page 4 in triplicate for insertion into the specification as filed. Yours Respectfully,
References Cited (Backward Citations)
No citation records indexed.
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