MZ1800 VHR Measuring System

Measuring Voltage Holding Ratio of LCD

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When researching and developing LCD (liquid crystal display) of TFT type, it is the most important and significant factor to measure and evaluate the voltage holding ratio (VHR) of LCD cell.
There are the following three methods regarding the measurement of VHR.

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[method 1] Area comparison method
VHR is calculated based on the following equation.



[method 2] Effective value method
VHR is calculated based on the following equation.


 




[method 3] Droop value method

VHR is calculated based on the following equation.



VHR measuring system consists of four components of Impedance Converter MZ101 as a signal conditioner, SHIELDING BOX ME8662N to protect a LCD cell against noise, Arbitrary Function Synthesizer MFG206 generating supply voltage and timing pulse and windows PC in which an A / D converter is installed.

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1. Impedance Converter MZ101

     Input is guard-shielded as shown below. Accordingly, VHR measurement of LCD cell is not affected by the stray

     capacity of a measuring cable.

MZ101 also has a switch to supply the voltage to LCD cell as shown below.


2. SHIELDING BOX ME8662N
     SHIELDING BOX ME8662N is necessary to protect LCD cell against noise and to measure VHR stably.

3. Arbitrary Function Synthesizer MFG206
     MFG206 operates as a voltage source which charges LCD cell and as a control signal source to control a switch 

     in MZ101. Timing diagram is shown below. FUNC OUT and SYNC OUT of MFG206 are connected to SUPPLY

     INPUT and CONTROL INPUT of MZ101 with two coaxial cables.


The supply voltage V0 can be changed by using AMPL (Amplitude) of MFG206. The maximum value of V0 is 10 volts.

4. Windows PC with A / D converter
     The A / D converter converts a waveform output at SIGNAL OUTPUT of MZ101 to 16 bits digital data and

      transfers these data Windows PC.

     SOFTWARE FOR VHR MEASUREMENT controls MFG206, displays a waveform from MZ101 and calculates VHR.


VOLTAGE HOLDING RATIO MEASURING SYSTEM FOR LCD

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MZ101 Specifications
Input terminal.
  Input resistance more than 1013ohm
  Input leakage current less than 1pA
  Input capacitance less than 10pF
  Rise time less than 350ns @ within ¡Ó7.5V input and 50ohm load
less than 450ns @ within ¡Ó10V input and 50ohm load
  Frequency response 1MHz (-3dB) @ 5Vp-p sine wave input
  Gain between input and output 1.0 ¡Ó2% @ no load
  Measurement input voltage range within ¡Ó10V
  Input damage level ¡Ó13V (AC + DCpeak) max
  Connector connector included guard
Supply input terminal
  Input resistance approx. 47ohm
  Measurement input voltage range within ¡Ó10V
  Input damage level ¡Ó20V (AC + DCpeak) max
  Connector BNC connector
  Charge time less than 30µs @ 1300pF load and 12V supply
Control input terminal.
  Signal level TTL level (active low)
  Input damage level ¡Ó20V (AC + DCpeak) max
  Connector BNC connector
Signal output terminal.
  Output offset voltage available adjustment at front panel
  Output impedance 50ohm (nominal)
  Connector BNC connector
General.
  Operating temperature 0 to 40¢XC (Guaranteed at 23 ¡Ó10¢XC)
  Operating humidity less than 40¢XC / 90%RH (Guaranteed at less than 33¢XC / 80%RH)
  Warmup time more than 30min.
  Power supply AC90V to 127V, 50 / 60Hz
  Dimensions 56 (H) ¡Ñ 300 (W) ¡Ñ 300 (D) mm
  Weight approx. 2.5kg
  Accessories Instruction manual (1pc), Fuse (2pcs), Measuring cable (1pc), Power cable (1pc)

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