| 摘要 |
<p>The present invention provides a photodosimeter for use by sunbathers and the like and which activates an alarm when a predetermined radiation dosage has been received by the user. The photodosimeter includes a photocell mounted within the housing and exposed to sunlight through a housing opening. This photocell generates an analog output signal proportional to the radiation which impinges upon the photocell. An A/D converter converts the analog signal to a digital signal which is connected to a microprocessor which periodically samples the output from the converter and updates a cumulative radiation dosage counter in memory. When the cumulative radiation dosage exceeds a user settable maximum an alarm is activated. The microprocessor is further programmed to test a plurality of electrical conditions of the photodosimeter and to activate the alarm by a fail safe conduit in the event that one or more conditions are unsatisfied. Specifically, the microprocessor compares the determined radiation dosage to ensure that it falls between 0 and a predetermined maximum amount which are indicative of a nonfunctioning and overload conditions, respectively. The microprocessor further compares the read radiation dosage with the previous maximum amount and, if the current radiation dosage is less than a predetermined percentage, for example 25%, of the maximum amount, indicative that the photocell has been covered or obscured, activates the alarm. Still other electrical conditions of the photodosimeter are reiteratively checked by the microprocessor.</p> |
