Backlight Inverter Time Control Circuit with Single Pin
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Solution Overview
Problem
Conventional time control circuits for backlight inverters require multiple externally connectable capacitors and pins, leading to increased production costs due to the complexity of controlling initial startup, soft start, and shutdown times.
Innovation Solution
A time control circuit for a backlight inverter that utilizes a single externally connectable capacitor with multiple comparator elements and current sources to control initial startup, soft start, and shutdown times, reducing the number of required pins and simplifying the circuit design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple externally connectable capacitors and pins are used to control initial startup, soft start, and shutdown times, then the time control precision is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines three separate time control functions (initial startup time T1, soft start time T2, and shutdown time T3) into a single integrated circuit block. Multiple capacitors (C1, C2, C3) are connected to a common connecting pin, allowing all three time parameters to be controlled through one external connection point rather than requiring three separate pins and capacitors. This merging approach maintains precise time control while reducing circuit complexity and manufacturing cost.
Solution Approach 2:
The connecting pin is designed to serve multiple functions simultaneously - it connects to multiple capacitors that collectively control three different time parameters (T1, T2, T3). This multi-functional design allows a single pin to replace what would traditionally require three separate pins, reducing the overall device complexity while maintaining the precision of individual time controls through the respective comparators and current sources.
2Adaptability or versatility
If multiple externally connectable capacitors and pins are used for time control, then the time setting flexibility is improved, but the ease of manufacture deteriorates
Solution Approach 1:
By merging multiple capacitor connections to a single connecting pin, the patent maintains the flexibility to independently adjust three different time parameters (T1, T2, T3) through external capacitors while significantly simplifying the manufacturing process. The reduced pin count and simplified external connections make the device easier to manufacture and assemble compared to the conventional approach requiring three separate pin connections.
3Ease of manufacture
If the number of external pins is reduced, then the manufacturing cost is decreased, but the device complexity must be managed internally
Solution Approach 1:
The patent segments the internal circuit into distinct functional blocks - three comparators (21, 22, 23), three current sources (IS1, IS2, IS3), and three zenor diodes (ZD1, ZD2, ZD3) - each dedicated to controlling a specific time parameter. This segmentation allows the internal circuit to handle the complexity of multiple time controls while maintaining a simplified external interface with reduced pin count, thereby lowering manufacturing costs.
Solution Approach 2:
Multiple capacitors (C1, C2, C3) are introduced as intermediary elements that connect the single connecting pin to the respective comparators. These capacitors serve as mediators that enable the reduced pin count to still provide independent time control for all three functions, allowing the external interface to be simplified while the internal circuit maintains its functional complexity through the capacitor-mediated connections.
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 effectively reduces production costs by minimizing the number of external connections while maintaining control over the necessary time settings, enhancing the efficiency and cost-effectiveness of the backlight inverter system.
Implementation Method 1
a capacitor C connected between a connecting pin CP and a ground
Implementation Method 2
a first comparator element for comparing a voltage of the capacitor and a pre-set first reference voltage to control an initial startup time; a second comparator element for comparing the voltage of the capacitor and a pre-set second reference voltage to control a soft start time
Data Source
AI summary
In a time control circuit, a capacitor is connected between a connecting pin and a ground. A first current source supplies a first current to the connecting pin. A first comparator element has a non-inverse terminal connected to a voltage of the capacitor and a pre-set first reference voltage, and controls the initial startup time. A second comparator element has an inverse terminal connected to the voltage of the capacitor and a pre-set second reference voltage, and controls the soft start time. Further, a current bypass controller includes a current bypass path between the connecting pin and the ground, which connects the current bypass path after the soft start time and blocks it at an input of a protective signal. Additionally, a third comparator element has an inverse terminal connected to the voltage of the capacitor and a pre-set third reference voltage, and controls the shutdown time.