Endoscope Light Source Cooling Control via Synchronized PWM
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light source apparatuses for endoscopes face challenges in cooling LED light sources due to large variations in light quantity and temperature, leading to insufficient or excessive cooling, which affects the LED's lifespan and can cause condensation.
Innovation Solution
The endoscope apparatus incorporates a semiconductor light-emitting device with a Peltier element for cooling, where the cooling device's drive current is synchronized with the light-emitting device's PWM pulse and adjusted based on temperature measurements to maintain optimal cooling, and includes structures to prevent condensation by managing temperature and humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a Peltier element is used to cool the LED, then cooling capability is improved, but temperature control precision deteriorates due to large variations in light quantity and heat generation
Solution Approach 1:
The patent implements dynamic cooling control by adjusting the drive current of the Peltier element in real-time based on feedback from temperature sensors. The cooling device drive control section modifies the cooling current according to the LED's operating state and measured temperature, enabling adaptive temperature management that responds to varying light emission conditions.
Solution Approach 2:
The patent employs feedback control through temperature sensors that continuously monitor the LED temperature and feed this information back to the cooling device drive control section. This closed-loop system adjusts the Peltier element's drive current based on actual temperature measurements, ensuring precise temperature tracking despite large variations in light quantity and heat generation.
2Reliability
If cooling intensity is increased to prevent LED degradation, then LED lifespan is improved, but condensation risk increases
Solution Approach 1:
The patent dynamically adjusts cooling parameters based on environmental and operational conditions. The cooling device drive control section modifies cooling current intensity according to ambient temperature, humidity levels, and LED operating state, reducing cooling intensity when condensation risk is high while maintaining sufficient cooling to prevent LED degradation under normal conditions.
Solution Approach 2:
The system automatically monitors its own thermal state through temperature sensors and adjusts cooling accordingly without external intervention. The feedback control mechanism enables the cooling system to self-regulate, reducing cooling intensity when the LED temperature approaches dangerous levels that would cause condensation, while maintaining adequate cooling to protect LED lifespan.
3Illumination intensity
If PWM control is used to adjust light quantity, then light output control is improved, but temperature variation follows light emission causing cooling challenges
Solution Approach 1:
The patent synchronizes the cooling cycle with the PWM light emission cycle. The cooling device operates in periodic pulses matched to the LED drive pulses, providing cooling during and after each light emission cycle. This periodic cooling action tracks the thermal cycles generated by PWM-controlled light emission, effectively managing temperature variations.
Solution Approach 2:
The cooling device is activated before and during the light emission pulse to preemptively manage heat generation. By applying cooling current in advance and during the PWM cycle, the system prevents excessive temperature rise before it occurs, rather than reacting after temperature has already increased, thereby better controlling temperature variations associated with PWM operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures effective cooling followability to temperature variations, preventing LED degradation and condensation, thereby ensuring reliable and consistent light output even under varying observation conditions.
Implementation Method 1
a cooling device configured to be able to cool the semiconductor light-emitting device
Implementation Method 2
a heat pipe for absorbing the heat of the thermoelectric element and transfer it to a heat sink
Implementation Method 3
a semiconductor light-emitting device that generates illuminating light to be supplied to the endoscope
Data Source
Figure 1
Figure 2~3
Figure 4(a)~5(b)
AI summary
A light source apparatus includes a semiconductor light-emitting device, a cooling device configured to be able to cool the semiconductor light-emitting device, a light-emitting device drive section that supplies a light-emitting device drive signal to the semiconductor light-emitting device, a cooling device drive section that supplies a cooling device drive signal to the cooling device, a light-emitting device drive control section that sets a duty ratio of the light-emitting device drive signal and controls an amount of light emission of the semiconductor light-emitting device, a temperature sensor that measures a temperature of the semiconductor light-emitting device, and a cooling device drive control section that controls the cooling device drive section so as to generate the cooling device drive signal having a same duty ratio as the duty ratio of the light-emitting device drive signal set by the light-emitting device drive control section and having timing synchronized with the light-emitting device drive signal and controls the cooling device drive section so as to adjust a signal level of the cooling device drive signal based on a measurement result of the temperature sensor.