Expiration indicator

• US 20060002448A1
• Filed: 07/01/2004
• Published: 01/05/2006
• Est. Priority Date: 07/01/2004
• Status: Active Grant

• Current Assignee: Robert M Parker
• Original Assignee: Robert M Parker
• Inventors: Parker, Robert
• Granted Patent: US 7,188,996 B2
• Time in Patent Office: Days
• US Class Current: 374/102
• CPC Class Codes: G01K 3/04 in respect of time

Abstract

A simple recording device using a stable electric resistance heater in thermal contact with an irreversible color changing time temperature material relatively insensitive to room temperatures to show and record the cumulative time an electrical appliance, battery, tool, instrument has been used. The device may use a plurality of thick film carbon printed resistive heater with a thermal gradient in contact with the time temperature material or a simple adhesive calibrated time temperature film on a surface mounted stable resistor. The indicator is in parallel or series with the power switch. The time temperature material is in thermal contact with a constant temperature heater when used in fluctuating ambient temperature conditions.

Claims

1. An expiration or timing or usage-recording indicator constructed of an irreversible time temperature (TTI) color changing film or material relatively insensitive to room temperature in thermal contact with a stable electrically resistive heating element.

2. An expiration or timing or usage indicator as described in claim 1 where the TTI material is hardly effected by ambient temperatures, but will change in hours or days at elevated temperatures.

3. An expiration indicator as described in claim 1 where the resistive heater is printed with stable carbon inks and is in thermal contact with the TTI material.

4. An expiration indicator as described in claim 1 where a plurality of heater elements are in contact with the TTI material.

5. An expiration indicator as described in claim 1 with a plurality of printed heater elements producing a thermal gradient in thermal contact with TTI on a thin substrate in air.

6. An expiration indicator as described in claim 5 that has calibration marks or a scale to show the amount of time used.

7. An expiration indicator as described in claim 5 that uses a positive thermal coefficient resistive ink heater to help maintain a constant temperature.

8. An expiration indicator as described in claim 1 that uses a polyswitch to provide a constant temperature source when electrically activated.

9. An expiration indicator as described in claim 1 or TTI film adhesively attached on a surface mounted resistor on a printed circuit board or other resistor.

10. The devices of claim 1 in parallel with a power supply A.C. or D.C. and a switch and load.

11. An indicating device or timer as described in claim 1 in series with an A.C. or D.C. supply and a switch.

12. A TTI film or material not in thermal contact with the heater to indicate elevated ambient temperatures.

13. Part of the TTI material not in thermal contact with the heater is printed with a passive dark color to compare and indicate when the color change is complete as in claim 12.