Timer and storage condition indicator

• US 4,408,557 A
• Filed: 04/17/1981
• Issued: 10/11/1983
• Est. Priority Date: 06/18/1979
• Status: Expired due to Fees

• Current Assignee: Micro-Circuits Company
• Original Assignee: Micro-Circuits Company
• Inventors: Bradley, Robert F., Bradley, Lindell P.
• Primary Examiner(s): YASICH, DANIEL
• Application Number:
  US06/255,119
• Time in Patent Office: 907 Days
• Field of Search: 116/308, 116/219, 116/207, 368/114, 368/120, 368/92
• US Class Current: 116/206
• CPC Class Codes: G01K 3/04 in respect of time

Abstract

A timer and storage conditions indicator for indicating the passage of a predetermined length of time under predetermined ambient physical environmental conditions, in which a carrier mixture is contained in a relatively confined area above a base layer. An absorptive layer is disposed on the base layer and accepts the carrier mixture at a predetermined rate. A barrier means is disposed between the carrier mixture and the absorptive layer, and the removal of the barrier activates the timer. Transfer means such as a capillary tube or a second absorptive layer may be disposed between the carrier mixture and the first mentioned absorptive layer.

Claims

1. A timer and storage conditions indicator adapted to indicate the passage of time integrated with various ambient physical environmental conditions, said indicator comprising a base layer of impervious material, a fluid carrier mixture containing a component the migration of which during operation of said indicator can be observed and indicates the passage of a predetermined length of time under predetermined ambient physical environmental conditions, said carrier mixture being in a stored condition in a relatively small area near one edge of said base layer until said indicator is activated, an absorptive layer on said base layer adapted to accept said carrier mixture within various elapsed time limits, a component in said indicator responsive to one or more of the ambient conditions, said component coacting with said fluid carrier mixture for causing the variation of said elapsed time limits by altering the rate of migration of said carrier mixture, a removable impervious barrier disposed between said carrier mixture and said absorptive layer, a cover layer disposed over and sealingly enclosing said absorptive layer and forming a capsule-like means for said carrier mixture near the one edge of said absorptive layer and means on said cover layer for indicating and for aiding in the indication of said migration rate within said elasped time limits.

2. A timer and storage conditions indicator as defined in claim 1 in which said removable barrier is a frangible wall portion of said capsule-like means, and said capsule-like means is flexible, permitting compression thereof to rupture said frangible wall portion.

3. A timer and storage conditions indicator as defined in claim 2 in which said cover layer is attached to said base layer between said capsule-like means and said absorptive layer by an adhesive soluble in said carrier mixture.

4. A timer and storage conditions indicator as defined in claim 1 in which said cover layer is attached to said base layer between said removable barrier and said absorptive layer by an adhesive soluble in said carrier mixture.

5. A timer and storage conditions indicator as defined in claim 1 in which said carrier mixture and said transfer layer are in vertical proximity, said removable barrier includes an impervious sheet folded to form first and second layers between said carrier mixture and said transfer layer, and one end of said impervious sheet extends outwardly from the edge of said indicator.

6. A timer and storage conditions indicator as defined in claim 1 in which a capillary tube is disposed between said capsule-like means and said absorptive layer.

7. A timer and storage conditions indicator as defined in claim 1 in which said absorptive layer is saturated with a fluid and said carrier mixture passes therethrough by means of diffusion.

8. A timer and storage conditions indicator as defined in claim 1 in which said capsule-like means is separated from said absorptive layer by a frangible wall and said frangible wall is rupturable by force exerted on said capsule-like means when the indicator is activated.

9. A timer and storage conditions indicator as defined in claim 1 in which a transfer means is disposed between said capsule-like means and said absorptive layer.

10. A timer and storage conditions indicator as defined in claim 1 in which a transfer layer of absorptive material having the characteristics of being opaque when dry and translucent when saturated is disposed on said absorptive layer, and said transfer layer is saturated by said carrier mixture to reveal symbols on said absorptive layer when the indicator is activated.

11. A timer and storage conditions indicator as defined in claim 1 in which said cover layer is opaque and extends over said absorptive layer, gaps are disposed in said opaque cover layer through which spaced regions of said absorptive layer can be observed, and said carrier mixture is contrasting in color to said absorptive layer.

12. A timer comprising a base layer of impervious material, an absorptive layer disposed on said base layer, a cover layer enclosing said layers and forming a capsule disposed at one end of said base layer adjacent said absorptive layer, a frangible wall portion of said capsule adapted to rupture when said timer is activated by external pressure exerted on said capsule, a carrier mixture contained in said capsule and transmittable in a migratory fashion through said frangible wall to said absorptive layer after said frangible wall is ruptured, said carrier mixture and at least one component in said absorptive layer coacting to migrate through said absorptive layer over a predetermined period of time, and means in the cover layer for detecting the presence of said carrier mixture in said absorptive layer and for aiding in the correlation of the detection thereof to the passage of said predetermined period of time.

13. A timer as defined in claim 12 in which a portion of said cover layer is attached to said base layer between said frangible wall and said absorptive layer by an adhesive soluble in said carrier mixture.

14. A timer as defined in claim 12 in which a capillary tube is disposed between said capsule and said absorptive layer.

15. A timer as defined in claim 12 in which a transfer layer is disposed on said absorptive layer, said transfer layer having the characteristics of being opaque when dry and translucent when saturated, and a means is provided for saturating said transfer layer with said carrier mixture when the timer is activated to reveal symbols on said absorptive layer.