Single PWM Circuit for LCD Power Supply Cost Reduction
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Solution Overview
Problem
The high cost of liquid crystal display (LCD) devices is attributed to the need for two pulse width modulation (PWM) circuits to drive the light source and liquid crystal panel, increasing the overall cost of the power circuit and the LCD device.
Innovation Solution
A power circuit design that incorporates a single PWM circuit to generate multiple direct voltages using a boost switching mode voltage stabilizer circuit, charge pump circuits, and voltage stabilizer circuits, reducing the number of PWM circuits required and minimizing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two PWM circuits are used to drive the light source and liquid crystal panel respectively, then the driving function is reliable, but the cost of the power circuit and LCD device increases
Solution Approach 1:
The patent applies multi-functionality by enabling a single PWM circuit to generate multiple pulse waves with different duty cycles that control different output voltages for both the light source and liquid crystal panel. The PWM circuit generates a first pulse wave for the light source and a second pulse wave for the liquid crystal panel, allowing one circuit to perform multiple driving functions that previously required two separate circuits.
Solution Approach 2:
The patent merges the functions of two separate PWM circuits into one unified PWM circuit. By combining the pulse generation and control functions, the design reduces the total number of PWM circuits from two to one, thereby lowering cost while maintaining the ability to reliably drive both the light source and liquid crystal panel through coordinated pulse wave generation.
2Ease of operation
If two PWM circuits are used for driving light source and liquid crystal panel, then the driving capability is sufficient, but the manufacturing cost increases
Solution Approach 1:
The PWM circuit is designed with multi-functionality to generate different pulse waves for different driving purposes. It can produce a first pulse wave with a first duty cycle for driving the light source and a second pulse wave with a second duty cycle for driving the liquid crystal panel, maintaining sufficient driving capability while reducing component count and manufacturing cost.
Solution Approach 2:
The patent combines the driving capabilities of two separate PWM circuits into a single integrated PWM circuit that can generate multiple pulse waves with different characteristics. This merging reduces the number of components that need to be manufactured and assembled, thereby reducing manufacturing cost while preserving the full driving capability needed for both light source and liquid crystal panel 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
The solution reduces the number of PWM circuits needed, thereby decreasing the overall cost of the power circuit and LCD device while maintaining efficient operation, and allows for adaptability to standby modes by controlling output levels.
Implementation Method 1
a first transforming circuit 250 and a second transforming circuit 270, respectively connected to the switching mode voltage stabilizer circuit 220
Data Source
AI summary
A power circuit includes a PWM circuit for generating a pulse wave, a first control signal and a second control signal, a switching mode voltage stabilizer circuit, a first control circuit and a second control circuit. The PWM circuit includes a pulse wave pin, a first control pin and a second control pin. The switching mode voltage stabilizer circuit receives the pulse wave via the pulse wave output pin, and converts an external input voltage into a first direct voltage under control of the pulse wave. The first control circuit receives the first control signal via the first control pin. The second control circuit receives the second control signal via the second control pin and the first direct voltage, and converts the first direct voltage into a second direct voltage.