# US 4,367,957 A · Time-lapse indicator or the like > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,367,957 A - Document ID: US4367957A - Status: Granted - Kind: A - Application number: 06/100,840 - Filed: 1979-12-06 - Granted: 1983-01-11 - Earliest claimed: 1978-07-28 - Assignees: Micro-Circuits Company - Inventors: Robert F. Bradley - Web page: https://patentgrep.com/patent/US4367957A ## CPC - G04F 1/00: Apparatus which can be set and started to measure-off predetermined or adjustably-fixed time intervals without driving mechanisms, e.g. egg timers - G07C 1/30: Parking meters (registering or indicating waiting time of vehicles by means driven by the vehicle G07C5/02; coin-freed parking meters G07F17/24) - G04F: TIME-INTERVAL MEASURING (measuring pulse characteristics G01R, e.g. G01R29/02; in radar or like systems G01S) - G07C: TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE ## Abstract A time-lapse indicator in which a receptacle contains a fluid material having numerous discrete particles dispersed in a liquid carrier, and a layer of absorbent material in close proximity to the receptacle, the receptacle and absorbent material being separated from one another by a wall which is broken when the time period is to be determined by the indicator. The indicator normally has a pair of electrodes for measuring the resistance of the fluid material after a portion of the liquid carrier has been absorbed therefrom in the absorbent material. Mechanisms for both activating and reading the indicator may be used. ## Claims ### Claim 1 A mechanism for activating a time-lapse indicator utilizing electrical or magnetic characteristics and having a layer containing fluid material with numerous discrete particles and a layer of absorbent material in close proximity to said first layer, separated therefrom by a frangible layer: said activating mechanism including a means for flexing said frangible layer to cause said layer to break into numerous pieces, thereby releasing the liquid in said fluid material to be absorbed by said absorbent material and thereby changing said characteristics of one of said layers, and means for feeding the indicator to said flexing means when the operation of the indicator is to be initiated. ### Claim 2 (depends on 1) A mechanism for activating a time-lapse indicator as defined in claim 1 in which said means for flexing said frangible layer consists of a pair of rollers having longitudinal ribs and grooves between which said time-lapse indicator is passed. ### Claim 3 A mechanism for reading a time-lapse indicator utilizing electrical or magnetic characteristics and having a fluid material containing a solid component of discrete particles and a fluid component and an absorbent material for absorbing said fluid component: said mechanism comprising a sensing means for determining the resistance of said fluid material after a portion of said fluid component has been absorbed by said absorbent material, and means indicating the resistance of said fluid material and thereby the length of time said fluid component has been absorbed by said absorbent material. ### Claim 4 (depends on 3) A mechanism for reading a time-lapse indicator as defined in claim 3 in which said last mentioned means includes a means responsive to the resistance of said fluid material for indicating the amount and length of time the liquid carrier has been absorbed by said absorbent material. ### Claim 5 A method of using a time-lapse indicator utilizing electrical or magnetic characteristics and having a layer of absorbent material and a layer of liquid, said layer of liquid having numerous discrete solid particles, a ruturable wall seperating seperating said layers, the steps comprising rupturing said wall to bring together said layer of absorbent material and said liquid to activate said liquid layer to progressively change the concentration of said particles therein and thereby to change said characteristics of the indicator as the duration of time increases, permitting a period of time to lapse after activation, and utilizing said change in said characteristics to determine the lapse of time after activation of said one layer. ### Claim 6 (depends on 5) A method of using a time-lapse indicator as defined in claim 5 in which said layer of liquid contains electrical conducting particles, and liquid is absorbed from said liquid layer by said layer of absorbent material, whereby said liquid layer becomes less resistant to an electrical current. ### Claim 7 (depends on 5) A method of using a time-lapse indicator as defined in claim 5 in which said layer of liquid contains magnetically permeable particles, and liquid is absorbed from said liquid layer by said layer of absorbent material, whereby said liquid layer becomes more permeable to a magnetic field. ### Claim 8 (depends on 6) The method as defined in claim 6 which includes the further step of determining the magnetic permeability of said liquid containing said solid particles. ### Claim 9 (depends on 5) A method of using a time-lapse indicator as defined in claim 5 in which said activated layer becomes more conductive to an electrical current, and in which said method includes a further step of passing a current through said activated layer to produce a signal indicating the lapse of time after activation. ### Claim 10 (depends on 6) A method of using a time-lapse indicator as defined in claim 6 in which an electric current is passed through said liquid and the degree of change in the resistance is measured for determining the lapse of time after activation. ### Claim 11 (depends on 10) A method of using a time-lapse indicator as defined in claim 10 in which said method includes a further step of utilizing said change in resistance to activate a timer for determining the lapse of time after said fluid has been introduced into said absorbent layer. ### Claim 12 In a method of using a time-lapse indicator having a layer of absorbent material, a layer of liquid material, a rupturable wall separating said layers, and numerous electrically conductive discrete solid particles in one of said layers: the steps comprising rupturing said wall to introduce said fluid into said absorbent layer for varying the concentration of said solid particles in said one layer, permitting a period of time to lapse after introducing said fluid into said absorbent layer, and sensing the lapse of time by determining the change in conductivity of said conductive particles produced by the flow of said liquid into said absorbent material after said fluid has been introduced into said absorbent layer. ### Claim 13 (depends on 12) The method defined in claim 12 in which said solid particles are disposed in said liquid and the method includes the further step of determining the resistance of said particle containing liquid. ### Claim 14 (depends on 12) A method defined in claim 12 in which said solid particles are disposed in said liquid and the method includes the further step of determining the degree of concentration of said particles in said liquid. ### Claim 15 (depends on 12) A method defined in claim 12 in which said solid particles are disposed in said liquid and the method includes the further step of determining the conductivity of said liquid containing said solid particles. ### Claim 16 (depends on 15) The method as defined in claim 15 in which said solid particles are disposed in said liquid and said further step includes determining the electrical conductivity of said particle containing liquid.