×

Projection-type liquid crystal display device

  • US 6,072,458 A
  • Filed: 04/24/1997
  • Issued: 06/06/2000
  • Est. Priority Date: 07/29/1996
  • Status: Expired due to Fees
First Claim
Patent Images

1. A projection-type liquid crystal display device comprising:

  • a light source means for emitting a luminous flux;

    a liquid crystal light valve means, which has a common electrode to which a common voltage is applied and a source electrode to which a video signal is applied, for modulating said luminous flux emitted by said light source means;

    a liquid crystal drive means for applying said common voltage to said common electrode and said video signal to said source electrode;

    a projection means for projecting said luminous flux modulated by said liquid crystal light valve means onto a screen;

    a liquid crystal temperature detecting means for detecting temperature in the vicinity of said liquid crystal light valve means; and

    a control means for controlling said common voltage on the basis of values detected by said liquid crystal temperature detecting means in such a way that fluctuation in a light transmittance of said liquid crystal light value means is reduced;

    wherein;

    if the value detected by said liquid crystal temperature detecting means at time (t-Δ

    t), where Δ

    t is a specified unit of time, is represented by D(t-Δ

    t), the value detected by said liquid crystal temperature detecting means at time t is represented by D(t), and a specified reference value is represented by Dth,when |D(t)-D(t-Δ

    t)|>

    Dth, said control means controls a common voltage amplitude on the basis of said values detected by said liquid crystal temperature detecting means in such a way that fluctuation in the light transmittance of said liquid crystal light valve means is reduced, and when |D(t)-D(t-Δ

    t)|≦

    Dth, a first processing is carried out repeatedly in such a way that said common voltage amplitude is held unchanging and constant;

    a value D(t'"'"') detected when a final change in said common voltage amplitude has been effected is stored; and

    when, during an iteration of said first processing, |D(t)-D(t-Δ

    t)|≦

    Dth and said common voltage amplitude is subjected to said first processing for a specified number of iterations in such a way that said common voltage amplitude is held constant and unchanging, when an absolute value |D(t)-(t'"'"')| of a change from detected value D(t) at time after which the subsequent specified period has elapsed and stored value D(t'"'"') is greater than a specified reference value Dth'"'"', said common voltage amplitude is controlled according to the detected value D(t), and when the absolute value |D(t)-D(t'"'"')| is equal to or less than said reference value Dth'"'"', said common voltage amplitude is subjected to a second processing in such a way that said common voltage amplitude is held unchanging and constant.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×