Systems and methods for regulating temperature and illumination intensity at the distal tip of an endoscope
The present specification describes a system and method for computing the temperature of the tip of a multiple viewing elements endoscope based on a measurement of junction temperatures of light emitting diode (LED) illuminators inside the tip. The measurement of temperature is used for taking corrective action if the temperature exceeds a limit. The temperature measurement is used for optimizing image parameters, as the performance of image sensors is affected by changes in ambient temperature.
1. An endoscopy system comprising:
an endoscope having a tip;
a plurality of viewing elements located at the endoscope tip, wherein each of said viewing elements comprises an image sensor having a field of view illuminated by one or more light emitting diode (LED) illuminators;
a circuit board comprising a circuit for measuring a voltage across each of said LED illuminators; and
a controller programmed to compute a temperature of each of said LED illuminators by using said measured voltage and a function representing a relationship between LED voltage and LED junction temperature for a given current,
wherein the controller is further programmed to compute an average of LED junction temperatures and use that average to compute the temperature at a given point on the endoscope tip, and
wherein a relationship between the average of LED junction temperatures and the temperature at the given point on the endoscope tip is pre-determined by measuring an average LED junction temperature and a corresponding temperature at the given point on the endoscope tip for a range of LED currents and identifying a relationship between average LED junction temperatures and temperatures for the given point on the endoscope tip.
2. The system of claim 1 , wherein the controller is further programmed to reduce a power of the LED illuminators if the average LED junction temperature exceeds a pre-determined limit.
3. The system of claim 1 , wherein the function representing the relationship between LED voltage and LED junction temperature is pre-determined by measuring LED voltage and LED junction temperature for a range of LED currents and identifying a relationship between LED voltage and junction temperature.
4. The system of claim 1 , wherein said relationship is estimated using regression analysis.
5. A method for determining a temperature in an endoscope, without using a separate, dedicated temperature sensor, wherein said endoscope comprises a plurality of viewing elements located at a distal tip of the endoscope and wherein each of said viewing elements comprises an image sensor having a field of view illuminated by one or more LED illuminators, said method comprising:
measuring a voltage across at least one of said LED illuminators;
computing a junction temperature for the at least one of said LED illuminators by using a value of the measured voltage and a function representing a relationship between LED voltage and LED junction temperature for a given current and for the at least one of said LED illuminators; and
computing an average of junction temperatures of at least two LED illuminators present in the endoscope and using that average to compute the temperature at a given point on the distal tip;
wherein an average of junction temperature of only the LED illuminators, which are directly adjacent the given point on the distal tip, are used to estimate the temperature at said given point.
6. The method of claim 5 , wherein an average of junction temperatures of all the LED illuminators is used to estimate the temperature at the given point on the distal tip.
7. The method of claim 5 , wherein a power of the at least one of said LED illuminator is reduced if a junction temperature of said LED illuminator exceeds a pre-determined limit.
8. The method of claim 5 , wherein the function representing the relationship between LED voltage and LED junction temperature is pre-determined by measuring LED voltage and LED junction temperature for a range of LED currents and identifying a relationship between the LED voltage and LED junction temperature.
9. The method of claim 5 , wherein a relationship between average LED junction temperature and the temperature at said given point on the distal tip is pre-determined by measuring average LED junction temperature and the temperature at a given point on the distal tip for a range of LED currents and identifying a relationship between the average LED junction temperature and the temperature at the given point.
10. A method for determining a temperature in an endoscope, wherein said endoscope comprises a plurality of viewing elements located in a distal tip of the endoscope and wherein each of said viewing elements comprises an image sensor having a field of view illuminated by one or more LED illuminators, said method comprising:
measuring a voltage across at least one of said LED illuminators; and
computing a junction temperature for the at least one of said LED illuminators by using a value of the measured voltage and a function representing a relationship between LED voltage and LED junction temperature for the at least one of said LED illuminators,
wherein the function representing the relationship between LED voltage and LED junction temperature is pre-determined by measuring LED voltage and LED junction temperature for a range of LED currents and identifying a relationship between the LED voltage and LED junction temperature.