Liquid crystal projection apparatus and driving method thereof

Claim 2

A liquid crystal projection apparatus comprising a plurality of liquid crystal display panels (10) having a plurality of liquid crystal portions (2) arranged in a matrix, in which pictures obtained through said plurality of liquid crystal display panels based on display data are projected and displayed in such a manner that they are superimposed on a screen, comprising: scanning means (8) for scanning each of said plurality of liquid crystal portions (2) in said plurality of liquid crystal display panels (10); and driving means (18, 31, 32, 33) for applying a driving voltage corresponding to display data to each of the liquid crystal portions scanned by said scanning means (8); said driving means (18, 31, 32, 33) performing control in such a manner that driving voltages to be applied to the liquid crystal portions (2) are inverted for every horizontal scanning period and also for every frame comprising an odd field and an even field, and that at least one of said plurality of liquid crystal display panels (10) receives driving voltages of the opposite polarities to the remaining liquid crystal display panels.

Claim 3

The liquid crystal projection apparatus according to claim 1, wherein said driving means comprises; a plurality of panel driving means (31, 32, 33) provided corresponding to said plurality of liquid crystal display panels (10) for sequentially applying driving voltages to columns of the liquid crystal portions (2) in the corresponding liquid crystal display panel (10); and control means (18) for controlling said plurality of panel driving means (31, 32, 33) in such a manner that said driving voltages derived from each of said plurality of panel driving means (31, 32, 33) are inverted in polarity for every horizontal scanning period and also for every frame, and that driving voltages derived from at least one of said plurality of panel driving means (31, 32, 33) have the opposite polarities to those of the driving voltages derived from the remaining panel driving means.

Claim 4

The liquid crystal projection apparatus according to claim 2, which further comprises synchronizing signal generating means (19) for generating a horizontal synchronizing signal and a vertical synchronizing signal, said control means (18) being responsive to said horizontal synchronizing signal and said vertical synchronizing signal for applying a plurality of inversion indicating signals indicative of inverting a driving voltage in polarity to each of said plurality of panel driving means (31, 32, 33), each of said plurality of inversion indicating signals being inverted for every horizontal scanning period and also for every frame and at least one of said plurality of inversion indicating signals having the opposite polarity to the remaining inversion indicating signals, and each of said plurality of panel driving means (31, 32., 33) being responsive to the corresponding inversion indicating signal for inverting a driving voltage in polarity.

Claim 5

The liquid crystal projection apparatus according to claim 3, wherein each of said plurality of panel driving means (31, 32, 33) comprises, signal inverting means (21) receiving a display signal corresponding to display data and being responsive to said inversion indicating signal for outputting either an inverted signal or a non-inverted signal of said display signal; and line driving means (23) for sequentially applying an output of said signal inverting means (21) to columns of the liquid crystal portions (2) in the corresponding liquid crystal display panel (10) as a driving signal.

Claim 6

The liquid crystal projection apparatus according to claim 4, wherein each of said plurality of liquid crystal portions (2) in said plurality of liquid crystal display panels (10) has one and the other electrodes, and each of said plurality of liquid crystal display panels (10) further comprises bias voltage generating means (23) responsive to said inversion indicating signal for generating a bias voltage of the opposite polarity to said driving voltage, said driving voltage being applied to said one electrode of said liquid crystal portion (2), said bias voltage being applied to said the other electrode of said liquid crystal portion (2).

Claim 7

The liquid crystal projection apparatus according to claim 5, wherein said line driving means (23) comprises sample and hold means (25) for sampling and holding an output of said signal inverting means (21) as a driving voltage; selecting means (24) for sequentially selecting driving voltages held by said sample and hold means (25); and buffer means (26) for applying a driving voltage selected by said selecting means (24) to the corresponding column of liquid crystal portions (2) in the corresponding liquid crystal display panel (10).

Claim 8

The liquid crystal projection apparatus according to claim 3, which further comprises synchronizing signals generating means (19) for generating a horizontal synchronizing signal and a vertical synchronizing signal, said liquid crystal display panel comprising first, second and third liquid crystal display panels (10), said plurality of panel driving means comprising first, second and third panel driving means (31, 32, 33), and said control means (18) comprising frequency-divided signal generating means (11, 12, 13, 14) responsive to said horizontal synchronizing signal and said vertical synchronizing signal for outputting a 1/2 frequency-divided signal obtained by dividing said horizontal synchronizing signal into 1/2 in frequency, a first 1/4 frequency-divided signal obtained by dividing said vertical synchronizing signal into 1/4 in frequency, a second 1/4 frequency-divided signal which is an inverted signal of said first 1/4 frequency-divided signal and a third 1/4 frequency-divided signal delayed by one field period as compared with said second 1/4 frequency-divided signal, first logic means (15) for performing exclusive logic sum operation of said 1/2 frequency-divided signal and said second 1/4 frequency-divided signal to apply the result thereof to said first panel driving means (31) as a first inversion indicating signal, second logic means (16) for performing exclusive logic sum operation of said 1/2 frequency-divided signal and said second 1/4 frequency-divided signal to apply the result thereof to said second panel driving means (32) as a second inversion indicating signal, and third logic sum means (17) for performing exclusive logic sum operation of said 1/2 frequency-divided signal and said third 1/4 frequency-divided signal to apply the result thereof to said third panel driving means (33) as a third inversion indicating signal.

Claim 9

A driving method of a liquid crystal projection apparatus comprising a plurality of liquid crystal display panels (10) having a plurality of liquid crystal portions (2) arranged in a matrix, in which pictures obtained through said plurality of first crystal display panels based on display data are projected and displayed in such a manner that they are superimposed on a screen, comprising the steps of; interlace-scanning said plurality of liquid crystal portions (2) in said plurality of liquid crystal display panels (10), applying driving voltages corresponding to display data to each of the scanned liquid crystal portions (2) and performing control in such a manner that the driving voltages to be applied to each of said liquid crystal portions (2) are inverted for every horizontal scanning period and also for every frame comprising an odd field and an even field, and that at least one of said plurality of liquid crystal display panels (10) receives driving voltages of the opposite polarities to the remaining liquid crystal display panels.

Claim 10

A driving method of a liquid crystal projection apparatus comprising a plurality of liquid crystal display panels (10) having a plurality of liquid crystal portions (2) arranged in a matrix, in which pictures obtained through said plurality of first crystal display panels based on display data are projected and displayed in such a manner that they are superimposed on a screen, comprising the steps of; interlace-scanning said plurality of liquid crystal portions (2) in said plurality of liquid crystal display panels (10), applying driving voltages corresponding to display data to each of the scanned liquid crystal portions (2) and performing control in such a manner that the driving voltages to be applied to each of said liquid crystal portions (2) are inverted for every horizontal scanning period and also for every frame comprising an odd field and an even field, and that at least one of said plurality of liquid crystal display panels (10) receives driving voltages of the opposite polarities to the remaining liquid crystal display panels.

Claim 11

A liquid crystal display device comprising a plurality of liquid crystal display panels (10) each having a matrix of display elements and means for superimposing the respective images produced by operation of said panels to form a composite display image, and display control means for generating signals to be applied to the panels to drive the display elements in accordance with an input video signal, each panel being scan driven in a succession of frame periods, wherein the drive signals are adapted to cause the drive voltages applied to the display elements of one or more of the display panels to be of opposite polarity to the drive voltages applied at the same time to the display elements of the other panel or panels.

Claim 12

A liquid crystal display device comprising a plurality of liquid crystal display panels (10) each having a matrix of display elements and means for superimposing the respective images produced by operation of said panels to form a composite display image, and display control means for generating signals to be applied to the panels to drive the display elements in accordance with an input video signal, each panel being scan driven in a succession of frame periods, wherein the drive signals are adapted to cause the drive voltages applied to the display elements of one or more of the display panels to be of opposite polarity to the drive voltages applied at the same time to the display elements of the other panel or panels.