Liquid Crystal Dimmer Circuit for Direct AC Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light control devices face challenges in reducing power consumption when driven by commercial AC power supplies, as they often require voltage reduction methods that increase size, weight, or decrease conversion efficiency.
Innovation Solution
A light control device configuration that includes a drive circuit and power supply circuit to control the AC voltage within safe limits for the liquid crystal layer, using voltage dividers and PWM control to manage the commercial power supply, ensuring the device operates within the withstand voltage of the liquid crystal layer without the need for additional power conversion or transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a variable auto-transformer (slidac) is used to reduce commercial power supply voltage, then the light control device can be driven within safe voltage limits, but the device size and weight increase
Solution Approach 1:
The invention extracts and eliminates the bulky variable auto-transformer (slidac) from the system by using an alternative voltage control method. Instead of physically reducing voltage through transformer components, the patent uses a series connection of the light control device with a resistance element, allowing direct connection to commercial power supply without the need for voltage-reducing transformation equipment.
Solution Approach 2:
The invention replaces the mechanical/electromagnetic voltage transformation system (slidac) with an electrical circuit solution using series resistance. This substitution eliminates the need for moving parts, magnetic cores, and complex transformer structures, thereby reducing device weight and size while maintaining voltage safety through circuit configuration.
2Reliability
If an AC/DC power supply circuit is used to convert commercial power supply, then the light control device can operate within voltage limits, but conversion efficiency decreases and power consumption increases
Solution Approach 1:
The invention maintains continuous AC operation of the light control device without rectification to DC. By keeping the system in continuous AC mode and using series resistance for voltage control, the patent avoids the energy losses associated with AC/DC conversion processes including rectification, filtering, and regulation, thereby maintaining higher overall efficiency.
Solution Approach 2:
The invention extracts and removes the AC/DC power supply circuit from the system entirely. Instead of converting AC to DC and then regulating voltage, the patent directly uses AC operation with series resistance control, eliminating the conversion process and its associated energy losses.
3Power
If commercial power supply is used directly, then the device can operate at full power, but the voltage exceeds the withstand voltage of the liquid crystal layer
Solution Approach 1:
The invention introduces a resistance element as an intermediary component in series with the light control device. This resistance element acts as a voltage divider, dropping excess voltage and ensuring that the voltage across the liquid crystal layer remains within safe withstand limits while still allowing the device to operate from full commercial power supply.
Solution Approach 2:
The invention changes the electrical parameters of the circuit by introducing series resistance, which alters the voltage distribution. This parameter change allows the system to operate at full commercial power while maintaining the liquid crystal layer voltage within safe operating parameters through the voltage-dividing effect of the series resistance.
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 reduces power consumption and heat generation, eliminates the need for size-increasing transformers, and allows for efficient operation using standard commercial power supplies, while maintaining the longevity of the liquid crystal layer.
Implementation Method 1
The ordinary light refractive index of the liquid crystal material and the refractive index of the polymer material are set to be approximately the same
Implementation Method 2
a light control device using a polymer dispersed liquid crystal or a polymer network liquid crystal capable of performing bright display
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A light control device (10) includes: a light control element (11) including a first layer stack and a second layer stack which include electrodes provided on base members, respectively, and a liquid crystal layer sandwiched between the first and second layer stacks; a switching element (T1) connected between an AC power supply and the light control element (11); a comparator (CP1) that detects whether or not the AC power supply is higher than a first voltage that is higher than 0 V and is lower than a maximum value of the AC power supply; and a control circuit (38) that performs PWM control or PFM control on the switching element (T1) if the AC power supply is higher than the first voltage.