LIQUID CRYSTAL DIMMING DEVICE AND LIQUID CRYSTAL DIMMING METHOD
FIG1 is a block diagram showing a circuit configuration in a control circuit section according to an embodiment of the present invention  FIG2 is a diagram illustrating the relationship between a voltage applied to a liquid crystal panel related to a first operation example of the embodiment and a transmittance through a liquid crystal panel
FIG1 is a block diagram showing a circuit configuration of the control section 20. In the same figure, alternating-current power of 100 [V] to 240 [V] from the commercial power supply 18 is supplied to an AC/DC converter portion 21 of the control section 20. The AC/DC converter portion 21 includes two AC/DC converters 21A and 21B.  FIG2 is a diagram illustrating the relationship between a voltage applied to the liquid crystal panel serving as a load and the transmittance of the liquid crystal panel, in the control section 20. If the same figure is explained assuming that the applied voltage is controlled in units of 1 [V], the frequency of a rectangular wave at a voltage of 0 (zero) [V] to 25 [V] applied to the liquid crystal panel is set to 100 [Hz]; the frequency of a rectangular wave at a voltage of 26 [V] to 30 [V] is set to 60 Hz; the frequency of a rectangular wave at a voltage of 31 [V] to 35 [V] is set to 30 [Hz]; and the frequency of a rectangular wave at a voltage of 36 [V] to 50 [V] is set to 1 [Hz]. However, in reality, flicker appears and the degree of visual recognition also varies depending on individual differences, so the results of selecting a frequency in accordance with the range of each drive voltage are as per the contents shown in FIG2. Compared to the control contents shown in FIG2 described above, the drive voltage is divided into two half ranges, and the drive frequency is switched and controlled with a single threshold "30 [V]" interposed between the two half ranges.
block diagram, diagram
22
switching circuit
18
commercial power supply
20
control section
40
about
10
window glass
23
microcomputer
['1. A liquid crystal optical modulation device that performs light control drive of a liquid crystal panel, the device comprising: an optical modulation control section that switches and sets a frequency of a drive voltage in the form of a rectangular wave applied to the liquid crystal panel in accordance with a range of the drive voltage.']