Application Cases

Experiment Name: Effect of Nanoparticle Doping on Response Time

Test Equipment: High-voltage amplifier, Signal Generator, Oscilloscope, Hot Stage Controller, Attenuator, Detector, etc.

Experimental Process:

Figure 1: Measurement setup for the response time of a VAN cell

Response time is also an important parameter affecting image sticking in liquid crystal displays. A shorter response time makes image sticking less likely to occur. The setup used to measure response time in the experiment is shown in Figure 1. The light source is a 632.8 nm red laser. The light passes through an attenuator, an adjustable aperture, a polarizer, and a λ/4 waveplate to become circularly polarized light, and then becomes linearly polarized light after passing through the polarizer. The optical axes of the polarizer and analyzer are set at 90° to each other. The hot stage maintains the liquid crystal cell temperature at 28°C. The signal generator outputs a combined waveform of a 1 kHz AC square wave signal and a DC signal, with a period of 2 seconds. This combined waveform is amplified by the high-voltage amplifier and then applied to the liquid crystal cell. When the voltage exceeds the threshold voltage of the liquid crystal cell, the detector detects the change in light intensity and transmits it to the oscilloscope. The dynamic response process of the liquid crystal can be observed on the oscilloscope.

Experimental Results:

Figure 2: Fall and rise times of negative LC mixtures doped with different concentrations of γ-Fe₂O₃ nanoparticles in VAN cells

Figure 3: Relationship between different doping concentrations and response time (a) Normalized transmittance vs. fall time; (b) Normalized transmittance vs. rise time; (c) Fall time vs. doping concentration; (d) Rise time vs. doping concentration

The effect of different γ-Fe₂O₃ nanoparticle doping concentrations on the response time, as measured in the experiment, is shown in Figure 2. It can be seen from the figure that nanoparticle doping has a certain influence on the response time. Figure 3(a) and Figure 3(b) show magnified views of the fall time and rise time, respectively, where the fall time corresponds to the voltage removal process and the rise time corresponds to the voltage application process. From Figure 3(c) and Figure 3(d), it can be observed that both the rise time and fall time first decrease and then increase with increasing doping concentration, reaching their minimum values at a doping concentration of 0.034 wt%. At this doping concentration of 0.034 wt%, the fall time can be shortened by 8.11% and the rise time can be shortened by 15.49%. The variation trend of SRDCV with the γ-Fe₂O₃ nanoparticle doping is consistent with that of the response time, indicating that the doping of γ-Fe₂O₃ nanoparticles effectively mitigates the image sticking phenomenon in the VAN display mode.

High-Voltage Amplifier Recommendation: ATA-7015

Figure: ATA-7015 High-Voltage Amplifier Specifications

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