The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 26, 1991
Filed:
Mar. 23, 1989
Beatrice M Nicholas, Tring, GB;
Alan Mosley, Berkhamsted, GB;
Cyril Hilsum, Pinner, GB;
Michael G Clark, Gerrards Cross, GB;
Abstract
A device for indicating whether a rise in temperature above a predetermined value has occurred includes a support member, such as a label, on which a temperature-sensitive material is deposited. The material includes a large number of fracturable microcapsules containing a medium which changes from a solid state to a liquid state at the predetermined temperature value. The viscosity of the medium in its liquid state and the material of the support member are chosen such that the distance d.sub.1 by which the medium flows across the support member after the fracturing of the microcapsules so as to activate the device is indicative of the time between activation of the device and cooling of the device to below the predetermined temperature value. If the temperature is subsequently allowed to rise above the predetermined value, the medium will again assume its liquid state and will flow further across the support member, reaching a distance of, say, d.sub.2, thus indicating that the rise in temperature has occurred. The material may be printed on the label as a bar code, so that any rise above the predetermined temperature level will be indicated by distortion of the bar code which renders it unreadable.