Personal dosimeter with reminder time

• US 4,320,393 A
• Filed: 12/19/1979
• Issued: 03/16/1982
• Est. Priority Date: 06/07/1978
• Status: Expired due to Term

• Current Assignee: Jean Engdahl
• Original Assignee: Jean Engdahl
• Inventors: Engdahl, Jean
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US06/105,192
• Time in Patent Office: 818 Days
• Field of Search: 340/600, 340/573, 340/309.1, 340/527, 250/395, 250/336, 250/388, 250/376, 250/377, 250/378, 250/369, 128/659
• US Class Current: 340/600
• CPC Class Codes: G01T 1/15 Instruments in which pulses generated by a radiation detector are integrated, e.g. by a diode pump circuit

Abstract

A device for individually checking exposure to radiation is sensitive to the radiation and produces an alarm (acoustic and/or optical) when a threshold radiation dose is reached. An included time-measuring device furthermore warns the user when a surveillance period has expired.

The radiation sensitive device may use an electret while the time-measuring device uses the drop in voltage of a battery occurring at the end of the discharge of the battery.

Claims

1. A dosimeter comprising:

means sensitive to radiation for producing a first alarm signal when a certain radiation dose is reached or exceeded; and

time measuring means for producing a second alarm signal when a surveillance period has expired, the second alarm signal being different from the first alarm signal and the expiration of the surveillance period being detected by a drop in voltage occurring at the end of the discharge of an energy source.

2. The dosimeter as claimed in claim 1 in which the energy source is a battery having a well defined capacity and having a relatively constant output voltage which drops rapidly when the battery is exhausted, the time-measuring means including a load resistor connected across the battery and circuit means for monitoring the drop in battery voltage across the load resistor while the battery discharges through the load resistor.

3. A dosimeter comprising:

means sensitive to radiation for producing a first alarm signal when a certain radiation dose is reached or exceeded, said means including an electret, the electric charge accumulated in the electret being progressively eliminated by irradiation; and

time-measuring means for producing a second alarm signal when a surveillance period has expired, the second alarm signal being different from the first alarm signal and the expiration of the surveillance period being detected by a drop in voltage occurring at the end of the discharge of an energy source.