Reference Voltage Generation Circuit Temperature Compensation
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Solution Overview
Problem
Conventional reference voltage generation circuits for LED elements in electro-photography printers struggle to compensate for the negative temperature dependence of light emission power and the temperature dependence of reference resistors, making it difficult to maintain consistent light emission power across varying temperatures, especially when the LED elements have different temperature coefficients.
Innovation Solution
A reference voltage generation circuit with a specific voltage output unit and temperature compensation circuit sections, utilizing a regulator circuit, bi-polar transistor elements, and resistors to output a reference voltage with a positive temperature coefficient, allowing for arbitrary temperature coefficient and voltage settings without increasing the number of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional reference voltage generation circuits are used, then the circuit structure is simple, but the light emission power cannot be maintained consistent across varying temperatures
Solution Approach 1:
The reference voltage generation circuit is divided into multiple functional blocks: a basic reference voltage generation block that generates a reference voltage with a first temperature coefficient, and a correction block that generates a correction voltage with a second temperature coefficient to compensate for LED light emission power variations. This segmentation allows independent optimization of each block's temperature characteristics.
Solution Approach 2:
The circuit utilizes temperature coefficient as a key parameter to resolve the contradiction. By generating a reference voltage with a positive temperature coefficient and adding a correction voltage with a negative temperature coefficient, the combined output achieves a temperature coefficient that compensates for LED light emission power variations, maintaining consistent light output across temperature ranges.
2Measurement precision
If the number of components is increased to improve temperature compensation, then temperature compensation precision improves, but manufacturing cost increases
Solution Approach 1:
The reference voltage generation circuit is designed to serve multiple functions: it generates the basic reference voltage, provides temperature compensation, and allows arbitrary setting of temperature coefficients. This is achieved by configuring existing components (operational amplifiers, resistors, transistors) to perform multiple roles, eliminating the need for additional dedicated temperature compensation components.
Solution Approach 2:
The circuit achieves arbitrary temperature coefficient settings by adjusting resistor ratios and operational amplifier configurations rather than adding more components. The temperature coefficient can be programmed through component value selection, providing high precision temperature compensation without increasing component count or manufacturing complexity.
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 enables precise temperature compensation of LED elements with various temperature dependences, maintaining consistent light emission power across temperature variations while keeping costs low by avoiding the need to increase the number of components.
Implementation Method 1
a regulator circuit (101) having a first terminal as a power source terminal connected to the power source VDD, a second terminal as an output terminal, and a third terminal as a ground terminal connected to ground
Implementation Method 2
a first circuit section (102, 103, 104) for outputting a reference voltage with a positive temperature coefficient from the specific voltage output from the specific voltage output unit
Implementation Method 3
a second circuit section (105, 106) for setting a level of the reference voltage output from the first circuit section
Implementation Method 4
the LED elements have light emission power having temperature dependence with a negative temperature coefficient
Implementation Method 5
When the LED is formed of a GaAsP element, the temperature coefficient is about −0.6%/° C. When the LED is formed of an AlGaAs element, the temperature coefficient is −0.25%/° C.
Data Source
AI summary
A reference voltage generation circuit for outputting a reference voltage from an input voltage includes a specific voltage output unit for outputting a specific voltage from the input voltage; a first circuit section for outputting the reference voltage with a positive temperature property from the specific voltage output from the specific voltage output unit; and a second circuit section for setting a level of the reference voltage output from the first circuit section. The specific voltage output unit is formed of a regulator circuit having a first terminal connected to a power source. The first circuit section is formed of a bi-polar transistor element connected to a second terminal of the regulator circuit. The second circuit section is formed of a resistor connected to the second terminal of the regulator circuit, a collector terminal of the bi-polar transistor element, and an emitter terminal of the bi-polar transistor element.