Method of driving liquid crystal display device

• US 3,921,162 A
• Filed: 04/04/1973
• Issued: 11/18/1975
• Est. Priority Date: 04/06/1972
• Status: Expired due to Term

• Current Assignee: Katsuji Hattori, Komei Asai, Masakazu Fukai, Seiichi Nagata
• Original Assignee: Katsuji Hattori, Komei Asai, Masakazu Fukai, Seiichi Nagata
• Inventors: Fukai, Masakazu, Nagata, Seiichi, Asai, Komei, Hattori, Katsuji
• Primary Examiner(s): Curtis, Marshall M.
• Application Number:
  US05/347,631
• Time in Patent Office: 958 Days
• Field of Search: 340/324M,166EL,336 178/30 350/16LC 219/216
• US Class Current: 345/101
• CPC Class Codes: G02F 1/133382 Heating or cooling of liquid crystal cells other than for activation, e.g. circuits or arrangements for temperature control, stabilisation or uniform distribution over the cell

Abstract

A method of driving a liquid crystal display device including a liquid crystal layer provided with electrodes on its two opposite surfaces, comprising the steps of applying a first signal for designating the electrode position and a voltage signal having a higher frequency to the electrodes on one surface, and applying and input signal and the signal of said higher frequency to the electrodes on the other surface. The signals are controlled by another signal of different frequency to drive the display device with an ac voltage. Temperature compensation can be performed by varying the magnitude or the frequency of the voltage signal according to the temperature level.

Claims

1. A method of driving a liquid crystal display device having a matrix structure including a nematic crystal layer and two groups of electrodes disposed on the respective surfaces of said liquid crystal layer, each of the electrodes in said two groups being driven by an associated controller having an inpput and a gating circuit, said method comprising the steps of applying first and second pulse driving voltages to the inputs of first and second selected controllers, each selected controller being associated with an electrode of one of said two groups to designate a selected electrode position, applying a first a.c. signal voltage having a frequency higher than that of said first or second pulse driving voltages to the inputs of the controllers associated with said two groups of electrodes, applying a second a.c. signal voltage having a frequency different from that of said first or second pulse driving voltages to the gating circuits of the controllers associated with said two groups of electrodes, said second a.c. signal controlling application of said pulse driving voltages and first a.c. signal to said electrodes, measuring the temperature adjacent said nematic liquid crystal, and changing the magnitudes of the voltages applied to all of the electrodes of said two groups to follow changes in the temperature of said liquid crystal layer, said changes in the magnitudes of the voltages applied to said electrodes causing dynamic scattering in said liquid crystal at the changed temperatures thereof at said selected electrode position and suppressing dynamic scattering at the other electrode positions, whereby the temperature range wherein dynamic scattering is produced is widened.

2. The method of driving a liquid crystal as defined by claim 1 which further includes the steps of inverting said first and second a.c. signal voltages before applying them to the inputs and gating circuits respectively of said controllers.

3. A method of driving a liquid crystal display device having a matrix structure including a nematic crystal layer and two groups of electrodes disposed on the respective surfaces of said liquid crystal layer, each of the electrodes in said two groups being driven by an associated controller having an input and a gating circuit, said method comprising the steps of applying first and second pulse driving voltages to the inputs of first and second selected controllers, each selected controller being associated with an electrode of one of said two groups to designate a selected electrode position, applying a first a.c. signal voltage having a frequency higher than that of said first or second pulse driving voltages to the inputs of the controllers associated with said two groups of electrodes, applying a second a.c. signal voltage having a frequency different from that of said first or second pulse driving voltages to the gating circuits of the controllers aSsociated with said two groups of electrodes, said second a.c. signal controlling application of said pulse driving voltages and first a.c. signal to said electrodes, measuring the temperature adjacent said nematic liquid crystal, and modifying the frequency of the voltages applied to the electrodes of said two groups in accordance with the measured temperature of said liquid crystal layer, whereby dynamic scattering is produced in said liquid crystal at said selected electrode position and dynamic scattering is suppressed at the other electrode positions.

4. The method of driving a liquid crystal as defined by claim 3 which further includes the steps of inverting said first and second a.c. signal voltages before applying them to the inputs and gating circuits respectively of said controllers.