Liquid-crystal luminous quantity adjuster, method for driving liquid crystal luminous quantity adjuster, and camera comprising liquid crystal luminous quantity adjuster
First Claim
1. A liquid-crystal light-amount adjusting device comprising:
- a driving-pulse generating circuit for generating driving pulses having pulsed voltages;
a liquid-crystal light-amount adjusting unit, to which the driving pulses are supplied, for changing an optical transmittance of a liquid crystal according to pulse shapes of the driving pulses; and
a control circuit for controlling frequencies and duty ratios of the driving pulses;
wherein the control circuit exercises control so that the driving-pulse generating circuit generates driving pulses for acceleration, having a pulse shape with a first frequency and a first duty ratio, and driving pulses for dimming, having a pulse shape with a second frequency that is different from the first frequency and a second duty ratio that is different from the first duty ratio.
1 Assignment
0 Petitions
Accused Products
Abstract
A liquid-crystal light-amount adjusting device in which the effective power of driving pulses for acceleration is optimized to improve response characteristics of optical transmittance, a method of driving the apparatus, and a camera including the apparatus. The liquid-crystal light-amount adjusting device according to the present invention includes a driving-pulse generating circuit (16) for generating driving pulses having pulsed voltages, a liquid-crystal light-amount adjusting unit (12) for changing the optical transmittance of a liquid crystal according to pulse shapes of the driving pulses, and a microcomputer (19) for controlling frequencies and duty ratios of the driving pulses. The microcomputer (19) exercises control so that the driving-pulse generating circuit (16) generates driving pulses including driving pulses for acceleration, having a pulse shape with a first frequency and a first duty ratio, and driving pulses for dimming, having a pulse shape with a second frequency that is different from the first frequency and a second duty ratio that is different from the first duty ratio.
7 Citations
7 Claims
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1. A liquid-crystal light-amount adjusting device comprising:
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a driving-pulse generating circuit for generating driving pulses having pulsed voltages;
a liquid-crystal light-amount adjusting unit, to which the driving pulses are supplied, for changing an optical transmittance of a liquid crystal according to pulse shapes of the driving pulses; and
a control circuit for controlling frequencies and duty ratios of the driving pulses;
wherein the control circuit exercises control so that the driving-pulse generating circuit generates driving pulses for acceleration, having a pulse shape with a first frequency and a first duty ratio, and driving pulses for dimming, having a pulse shape with a second frequency that is different from the first frequency and a second duty ratio that is different from the first duty ratio. - View Dependent Claims (2, 3)
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4. A method of driving a liquid-crystal light-amount adjusting device that changes an optical transmittance thereof in accordance with pulse shapes of driving pulses supplied to a liquid crystal,
wherein, before driving pulses having a pulse shape in accordance with a desired optical transmittance is supplied to the liquid crystal, driving pulses having a frequency that is different from a frequency of the driving pulses having the pulse shape in accordance with the desired optical transmittance is supplied to the liquid crystal.
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5. A camera comprising:
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an optical system for focusing light coming from a target on an imaging surface;
a liquid-crystal light-amount adjusting unit for adjusting the amount of the light that reaches the imaging surface, by changing an optical transmittance of a liquid crystal;
a driving-pulse generating circuit for generating driving pulses having pulsed voltages, the driving pulses being supplied to the liquid crystal to change the optical transmittance; and
a control circuit for controlling frequencies and duty ratios of the driving pulses;
wherein the control circuit exercises control so that the driving-pulse generating circuit generates driving pulses for acceleration, having a first frequency and a first duty ratio, and driving pulses for dimming, having a second frequency that is different from the first frequency and a second duty ratio that is different from the first duty ratio. - View Dependent Claims (7)
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6. A camera comprising:
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an optical system for focusing light coming from a target on an imaging surface;
a liquid-crystal light-amount adjusting unit for adjusting the amount of the light that reaches the imaging surface, by changing an optical transmittance of a liquid crystal;
a driving-pulse generating circuit for generating driving pulses having pulsed voltages, the driving pulses being supplied to the liquid crystal to change the optical transmittance; and
a control circuit for controlling a frequency and a duty ratio of the driving pulses;
wherein the control circuit changes the frequency of the driving pulses during-imaging for one screen.
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Specification