Liquid crystal device

Abstract

There is provided a liquid crystal comprising a liquid crystal panel with a memory effect (2) sandwiching liquid crystals of a memory effect, a driving circuit (10) outputs driving voltage for driving the liquid crystal panel with a memory effect (2) and a temperature sensor for detecting an ambient temperature, wherein the driving circuit (10) includes a control circuit (11) for varying a driving voltage. The control circuit has a first temperature compensation range where the driving voltage is increased from a high temperature side toward a lower temperature side according to temperature information detected by the temperature sensor (3), and a second temperature compensation range where the driving voltage is rendered in a maximum value at a predetermined temperature, or rendered substantially equal to, or smaller than the maximum value on a side of the boundary, lower than the predetermined temperature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of a first embodiment of a liquid crystal device according to the invention;

FIG. 2 is a flow chart showing a first operation of a driving circuit of the liquid crystal device;

FIG. 3 is a graph showing an example of a relationship between an ambient temperature, and a pulse width of a driving voltage with reference to the first operation;

FIG. 4 is a graph showing another example of the relationship between the ambient temperature, and the pulse width of the driving voltage with reference to the first operation;

FIG. 5 is a flow chart showing a second operation of the driving circuit in FIG. 1;

FIG. 6 is a graph showing an example of the relationship between the ambient temperature, and the pulse width of the driving voltage with reference to the second operation;

FIG. 7 is a graph showing another example of the relationship between the ambient temperature, and the pulse width of the driving voltage with reference to the second operation;

FIG. 8 is a block diagram showing a configuration of a second embodiment of a liquid crystal device according to the invention;

FIG. 9 is a flow chart showing a first operation of a driving circuit of the liquid crystal device;

FIG. 10 is a flow chart showing a second operation of the driving circuit of the liquid crystal device;

FIG. 11A is a schematic plan view showing a configuration of arrangement of polarizers of a conventional ferroelectric liquid crystal device;

FIG. 11B is a schematic sectional view showing a structure of the conventional ferroelectric liquid crystal device;

FIG. 12 is a diagram showing variation in light transmittance in relation to a driving voltage of the ferroelectric liquid crystal device;

FIG. 13 is a waveform chart showing an example of a composite driving voltage applied to the ferroelectric liquid crystal device;

FIG. 14 is a graph showing relationship between an ambient temperature, and a pulse width of a driving voltage in the case of conventional temperature compensation;

FIG. 15 is a view showing humidity characteristics of threshold values of the driving voltage, causing the ferroelectric liquid crystal device to undergo switching; and

FIGS. 16A, 16B, 17A, 17B each are a schematic view for describing the action of the ferroelectric liquid crystal device entering an abnormal operation region.

Claims

1. A liquid crystal device capable of executing temperature compensation, comprising a liquid crystal panel with a liquid crystal layer sandwiched between a pair of substrates having respective driving electrodes, over respective surfaces of the substrates, opposed to each other, a driving circuit for outputting a driving voltage for driving the liquid crystal panel, and a temperature sensor for detecting an ambient temperature: the driving circuit including a control circuit for varying a pulse width or a pulse height of the driving voltage;the control circuit including a first temperature compensation range where the pulse width or the pulse height of the driving voltage is increased from a high temperature side toward a low temperature side in a temperature compensation range of the liquid crystal panel, according to temperature information detected by the temperature sensor, and a second temperature compensation range where the pulse width or the pulse height of the driving voltage is rendered maximum at a predetermined temperature at the boundary between the first temperature compensation range, and the second temperature compensation range before the pulse width or the pulse height of the driving voltage is rendered substantially equal to, or smaller than a maximum pulse width or a maximum pulse height of the driving voltage, on a side of the boundary, lower than the predetermined temperature.

2. The liquid crystal device according to claim 1, wherein the predetermined temperature is not higher than 0° C.

3. The liquid crystal device according to claim 1, wherein the temperature compensation range including the first temperature compensation range and second temperature compensation range is in a range of −10° C. to +60° C.

4. The liquid crystal device according to claim 1, wherein the liquid crystal layer is composed of liquid crystals with a memory effect having at least two stable states.

5. The liquid crystal device according to claim 4, wherein the driving voltage outputted by the driving circuit contains a reset pulse for resetting the liquid crystals with a memory effect to one of the two stable states, and outputs the reset pulse sufficient for resetting the liquid crystals with a memory effect to the one of the two stable states in the second temperature compensation range.

6. The liquid crystal device according to claim 5, wherein the driving circuit outputs the reset pulse sufficient for resetting the liquid crystals with a memory effect to the one of the two stable states at any suitable temperature in the second temperature compensation range.

7. The liquid crystal device according to claim 5, wherein the liquid crystal device further comprises a humidity sensor for detecting an ambient humidity, and the driving circuit outputs the reset pulse sufficient for resetting the liquid crystals with a memory effect to the one of the two stable states in the second temperature compensation range on the basis of humidity information detected by the humidity sensor.

8. The liquid crystal device according to claim 7, wherein the humidity information detected by the humidity sensor is information on humidity at the predetermined humidity or lower.

9. The liquid crystal device according to claim 7, wherein the humidity information detected by the humidity sensor is information on continuation of a condition of the detected humidity being at the predetermined humidity or lower for a predetermined time length.

10. The liquid crystal device according to claim 5, wherein the driving circuit stops the driving voltage applied to the liquid crystal panel with a memory effect after the liquid crystal panel with a memory effect is reset.

11. The liquid crystal device according to claim 10, wherein the liquid crystal device further comprises a humidity sensor for detecting an ambient humidity, and the driving voltage circuit stops the driving voltage applied to the liquid crystal panel with a memory effect according to the humidity information detected by the humidity sensor.

12. The liquid crystal device according to claim 11, wherein the humidity information detected by the humidity sensor is information on humidity at the predetermined humidity or lower.

13. The liquid crystal device according to claim 11, wherein the humidity information detected by the humidity sensor is information on continuation of a condition of the detected humidity being at the predetermined humidity or lower for a predetermined time length.

14. The liquid crystal device according to claim 4, wherein the liquid crystals with a memory effect is composed of liquid crystals exhibiting the smectic phase.