公开(公告)号：EP0272871B1

公开(公告)日：1993-03-10

申请号：EP87311045.6

申请日：1987-12-15

申请人： XEROX CORPORATION

发明人： Haas, Werner Erwin Louis ,  Andrews, John Richard

IPC分类号： G01R29/24 ,  G01R15/07 ,  G02F1/1333 ,  G01R5/28

CPC分类号： G01R15/241 ,  G01R29/12

公开(公告)号：EP0272871A3

公开(公告)日：1988-07-27

申请号：EP87311045

申请日：1987-12-15

申请人： XEROX CORPORATION

发明人： Haas, Werner Erwin Louis ,  Andrews, John Richard

IPC分类号： G01R29/24 ,  G02F01/13 ,  G01R05/28

CPC分类号： G01R15/241 ,  G01R29/12

摘要： A voltage sensing device comprising a liquid crystal cell (10) electrically connected to a charged surface and having a light transmissivity varying with applied voltage. A light source (30) is directed through the liquid crystal cell, and a light detector (32) detects changes in the intensity of light directed through the cell and providing an output indicative of variations in voltage on the charged surface. Polarizers (24, 26), which polarize light from the light source directed through the liquid crystal cell, and analyze light exiting the cell, convert electro-optically induced phase changes into intensity changes. A saturation level biasing voltage is periodically applied to the liquid crystal cell to set the cell to a reference level, clearing the cell of transient polarization effects. A second reference liquid crystal cell may be provided, electrically coupled to a reference voltage. Signals from the charged surface derived by the liquid crystal cell connected to the surface are compared with reference signals derived by the reference cell prior to output of the signal to eliminate a time-based drift component from the output.

公开(公告)号：EP0272871A2

公开(公告)日：1988-06-29

申请号：EP87311045.6

申请日：1987-12-15

申请人： XEROX CORPORATION

发明人： Haas, Werner Erwin Louis ,  Andrews, John Richard

IPC分类号： G01R29/24 ,  G01R15/07 ,  G02F1/1333 ,  G01R5/28

CPC分类号： G01R15/241 ,  G01R29/12

摘要： A voltage sensing device comprising a liquid crystal cell (10) electrically connected to a charged surface and having a light transmissivity varying with applied voltage. A light source (30) is directed through the liquid crystal cell, and a light detector (32) detects changes in the intensity of light directed through the cell and providing an output indicative of variations in voltage on the charged surface. Polarizers (24, 26), which polarize light from the light source directed through the liquid crystal cell, and analyze light exiting the cell, convert electro-optically induced phase changes into intensity changes. A saturation level biasing voltage is periodically applied to the liquid crystal cell to set the cell to a reference level, clearing the cell of transient polarization effects. A second reference liquid crystal cell may be provided, electrically coupled to a reference voltage. Signals from the charged surface derived by the liquid crystal cell connected to the surface are compared with reference signals derived by the reference cell prior to output of the signal to eliminate a time-based drift component from the output.

摘要翻译： 一种电压感测装置，包括电连接到带电表面并具有随施加电压变化的光透射率的液晶单元（10）。 光源（30）被引导通过液晶单元，光检测器（32）检测穿过单元的光的强度变化，并提供指示带电表面上的电压变化的输出。 偏振器（24,26），其偏振来自通过液晶单元的光源的光，并且分析离开单元的光，将电光感应相位变化转换为强度变化。 周期性地向液晶单元施加饱和电平偏置电压以将电池设置为参考电平，从而清除瞬态极化效应的单元。 可以提供电耦合到参考电压的第二参考液晶单元。 将从连接到表面的液晶单元导出的带电表面的信号与在输出信号之前由参考单元导出的参考信号进行比较，以从输出中消除基于时间的漂移分量。