US 4,784,149 AGranted

Infrared thermometer with automatic calibration

AssigneeOptical Sensors Incorporated

InventorsHerbert L. Berman, Richard W. Singer

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Abstract

Infrared radiation emitted from tissue surface of body cavity is measured by an infrared sensor located within a probe which generates a signal voltage dependent on the difference in temperature between the tissue and the infrared sensor. An additional ambient sensor measures the ambient temperature of the infrared sensor. The signals of the two sensors are added. To calibrate and eliminate errors, the housing of the device is provided with a chamber shaped to receive the probe and containing a target viewed by the infrared sensor. An error signal is thus generated which is added to the signals of the two sensors when they view the body tissue. A disposable, sanitary cover for the probe is made of a truncated polyethylene member of substantially uniform thickness closed by an end window. A filter in the probe suppresses absorption bands of polyethylene to eliminate errors due to minor variations in cover thickness.

Claims13

Dependent claims

In combination, a probe for an infrared thermometer comprising a body, first means at one end of said body having a window at its distal end for admission of infrared radiation from tissue emitting radiation, an infrared sensor in said body emitting radiation, an infrared sensor in said body emitting a first signal responsive to the radiation entering through said window, said infrared sensor being in thermal equilibrium with said body to assume the temperature of said body, an ambient sensor in thermal contact with said infrared sensor emitting a second signal responsive to the temperature of said infrared sensor, second summing means summing the output signals of said sensors, third display means responsive to said summing means indicating the temperature of said tissue;

and fourth means forming a chamber having an open first end and a closed second end, a target in said chamber adjacent said second end, said target being in thermal equilibrium with said fourth means to assume the temperature of said fourth means, whereby when said probe is inserted in said chamber it receives infrared energy of measured intensity from said target, and fifth error correcting means for adding an error signal to said second summing means to correct error in the signal from said infrared sensor.

Dependencies are inferred from the claim text.