OCXO Oven Temperature Feedback for Quartz Resonator Stability
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Solution Overview
Problem
Conventional oven controlled crystal oscillators (OCXOs) face challenges in maintaining a constant temperature for quartz resonators due to heat leakage, leading to nonlinear temperature characteristics and the need for complex correction functions to stabilize oscillation frequencies across varying ambient temperatures.
Innovation Solution
A thermostatic oven type electronic instrument with a feedback system that adjusts the set temperature of the quartz resonator based on the outside air temperature, using a comparator, control means, and feedback system to maintain a constant target temperature by adding a feedback amount to the set temperature, ensuring the temperature difference is minimized and oscillation frequency stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is integrated into the module to detect temperature, then the temperature control system can be implemented, but the distance between the temperature sensor and the quartz resonator becomes long, causing temperature measurement inaccuracy
Solution Approach 1:
The patent divides the temperature control system into two independent parts: a temperature sensor integrated into the module to detect module temperature, and a separate temperature control unit that uses this information to control the heater. This segmentation allows the sensor to be positioned optimally for measurement while the control logic resides separately, addressing the distance issue by using the sensor's position for accurate measurement rather than placing it near the resonator.
Solution Approach 2:
The patent introduces the module temperature as an intermediary parameter. Instead of directly measuring the quartz resonator temperature, the system measures the module temperature (which correlates with resonator temperature) and uses this intermediate measurement to control the heater, thereby indirectly achieving resonator temperature control without requiring direct contact with the resonator.
2Stability of the object's composition
If the set temperature is fixed to maintain the quartz resonator at a constant temperature, then temperature stability is achieved, but heat leakage from the thermostatic oven causes the actual resonator temperature to deviate from the set temperature
Solution Approach 1:
The patent implements a feedback control system where the temperature sensor continuously monitors the module temperature, and this information is fed back to the temperature control unit. The control unit adjusts the heater power based on the temperature difference between the measured module temperature and the target resonator temperature, compensating for heat leakage and maintaining stable resonator temperature despite energy loss.
Solution Approach 2:
The patent changes the control parameter from directly controlling the set temperature to controlling the heater power based on module temperature feedback. By adjusting the heater power dynamically rather than maintaining a fixed set temperature, the system compensates for varying heat leakage conditions and maintains stable resonator temperature.
3Measurement precision
If a feedback system is implemented to compensate for heat leakage, then temperature control accuracy is improved, but the system complexity increases due to additional control components
Solution Approach 1:
The patent makes the temperature control unit multi-functional by having it perform both temperature measurement processing and heater control functions. Rather than adding separate dedicated components for each function, the control unit integrates multiple responsibilities, reducing overall system complexity while maintaining accurate temperature control through feedback.
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 approach allows for the stable operation of quartz resonators by maintaining constant temperature characteristics, even with fluctuating outside air temperatures, ensuring continuous and accurate oscillation signals.
Implementation Method 1
a measured temperature signal V_Tic which represents a measured temperature Tic based on an outside air temperature Tout detected by a temperature sensor 2
Implementation Method 2
a comparator 8 compares a measured temperature signal V_Tic representing the measured temperature Tic with a set temperature signal V_Tr representing a set temperature Tr
Implementation Method 3
controls the amount of heat generation by a heater (heat source) 1 via a transistor (control means) 10
Implementation Method 4
a thermostatic oven 100 which is configured to compare a set temperature and a measured temperature based on an outside air temperature measured by a temperature sensor 2 and which is controlled so that a temperature difference between the measured temperature and the set temperature is narrowed
Data Source
AI summary
To provide an oven controlled crystal oscillator which can keep constant the temperature of a quartz resonator housed within a thermostatic oven, thereby ensuring stable operation of the quartz resonator. An oven controlled crystal oscillator has a control system for exercising control so that the temperature of a quartz resonator becomes a target temperature Ttarg of a predetermined fixed value. The quartz resonator is housed within a thermostatic oven which is configured to compare a set temperature Tr and a measured temperature Tic based on an outside air temperature measured by a temperature sensor and which is controlled so that a difference between both temperatures is narrowed. The quartz resonator has characteristics influenced by an environmental temperature. The control system adds a predetermined feedback amount δT to the target temperature Ttarg of the fixed value to generate a new set temperature Tr for comparison with the measured temperature Tic so that when the measured temperature Tic lowers, the set temperature Tr becomes high, or when the measured temperature Tic rises, the set temperature Tr becomes low.