Driving Circuit PWM Control for Light Emitting Units
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Solution Overview
Problem
Existing light emitting unit driving circuits using pulse-width modulation (PWM) struggle with efficient luminance control, as they often require fixed optimum currents and lack flexibility in managing light emission based on varying data signals.
Innovation Solution
A driving circuit comprising a data memory circuit, a current source, a PWM control circuit, and a buffer circuit, which includes a plurality of switches to generate and control PWM signals for managing the flow of driving current through light emitting units, allowing for dynamic luminance adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PWM driving method with fixed optimum current is used, then luminance control is achieved, but flexibility in managing light emission based on varying data signals is lost
Solution Approach 1:
The patent implements dynamic PWM control by replacing fixed current sources with switchable current paths. The pixel circuit includes multiple current sources (first current source, second current source) that can be selectively activated based on data signals, enabling the circuit to adapt its driving characteristics dynamically rather than operating with fixed parameters.
Solution Approach 2:
The invention changes the operating parameters of the light emitting unit by varying the driving current level according to data signals. The pixel circuit can switch between different current levels (first driving current, second driving current) to achieve grayscale control and luminance adjustment, transforming the fixed-parameter approach into a variable-parameter system.
2Manufacturing precision
If multiple transistor types are used for PWM control, then precise luminance control is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent achieves precise luminance control using transistors of the same type (all N-type or all P-type). The switching and control functions are implemented using only one transistor type, eliminating the need for mixed transistor technologies. This homogeneous approach maintains manufacturing simplicity while achieving the required control precision through clever circuit architecture.
Solution Approach 2:
The control transistor serves multiple functions within the pixel circuit: it acts as a switch for PWM modulation, a regulator for current control, and a selector for different driving modes. By making the control transistor multi-functional, the circuit achieves precise luminance control without requiring specialized transistors for each function, thereby simplifying the manufacturing process.
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
Enables precise control of light emitting unit luminance by generating PWM signals based on data signals, reducing manufacturing costs by allowing for either P-type or N-type transistors to be used in the same process, and improving operational efficiency.
Implementation Method 1
a light emitting unit XLED... the second switch 150 passes the driving current IC through the light emitting unit XLED according to the PWM signal SEM so that a driving current IC flows through the light emitting unit XLED, then the light emitting unit XLED emits light
Data Source
AI summary
A driving circuit for illuminating a light emitting unit is provided. The driving circuit includes a data memory circuit, a current source, a PWM control circuit, a buffer circuit, and a second switch. The data memory circuit stores a data signal according to a scan signal. The current source generates a driving current. The PWM control circuit generates a PWM signal according to an enable signal and the data signal stored in the data memory circuit. The buffer circuit receives the PWM signal to generate a PWM signal. The second switch passes the current source through the light emitting unit according to the PWM signal so that the driving current flows through the light emitting unit.