Optical measuring device having d.c. component elimination
First Claim
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1. An optical measuring device, comprising:
- a sensor having a light emitting element which emits light flashes to a subject of detection by being supplied with electric power from a battery for a prescribed duration at prescribed intervals and a light sensitive element which receives reflected light from the subject;
a subtractor which subtracts a d.c. component from a sensed signal provided by the light sensitive element, thereby extracting a variation component;
an amplifier which amplifies an output signal of the subtractor;
an A/D converter which implements an A/D conversion for an output signal of the amplifier; and
a d.c. component modifying means which modifies a d.c. component level based on an A/D-converted value of the sensed signal provided by the light sensitive element.
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Abstract
An optical measuring device includes a sensor which emits light flashes toward a subject of detection with a light emitting element which is supplied with electric power from a rechargeable battery for a certain duration at certain intervals and receives reflected light from the subject with a light sensitive element. A subtractor subtracts a d.c. component from a sensed signal provided by the light sensitive element, thereby extracting a variation component. The subtractor has its output signal amplified with an amplifier, with the output thereof being A/D-converted with an A/D converter.
20 Citations
11 Claims
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1. An optical measuring device, comprising:
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a sensor having a light emitting element which emits light flashes to a subject of detection by being supplied with electric power from a battery for a prescribed duration at prescribed intervals and a light sensitive element which receives reflected light from the subject;
a subtractor which subtracts a d.c. component from a sensed signal provided by the light sensitive element, thereby extracting a variation component;
an amplifier which amplifies an output signal of the subtractor;
an A/D converter which implements an A/D conversion for an output signal of the amplifier; and
a d.c. component modifying means which modifies a d.c. component level based on an A/D-converted value of the sensed signal provided by the light sensitive element. - View Dependent Claims (2, 3)
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4. An optical measuring device, comprising:
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a sensor having a light emitting element which emits light flashes to a subject of detection by being supplied with electric power from a battery for a prescribed duration at prescribed intervals and a light sensitive element which receives reflected light from the subject;
a subtractor which subtracts a d.c. component from a sensed signal provided by the light sensitive element, thereby extracting a variation component;
an amplifier which amplifies an output signal of the subtractor;
an A/D converter which implements an A/D conversion for an output signal of the amplifier;
wherein data of the d.c. component of the sensed signal is delivered in addition to a data of A/D-converted value provided by the A/D converter, and wherein the data of the d.c. component of the sensed signal is determined from the sensed signal without being applied to the subtractor. - View Dependent Claims (5)
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6. An optical measuring device comprising:
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a sensor having a light emitting element which emits light flashes to a subject of detection by being supplied with electric power from a battery for a prescribed duration at prescribed intervals and a light sensitive element which receives reflected light from the subject;
a subtractor which subtracts a d.c. component from a sensed signal provided by the light sensitive element, thereby extracting a variation component;
an amplifier which amplifies an output signal of the subtractor;
an A/D converter which implements an A/D conversion for an output signal of the amplifier; and
control means for decreasing a level of the d.c. component by a prescribed amount each time an A/D-converted value provided by the A/D converter exceeds a prescribed upper level, and for decreasing the electric power supplied to the light emitting element when the level decreasing control means continues to decrease the level of the d.c. component a predetermined number of times. - View Dependent Claims (7, 8, 10)
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9. An optical measuring device comprising:
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a sensor having a light emitting element which emits light flashes to a subject of detection by being supplied with electric power from a battery for a prescribed duration at prescribed intervals and a light sensitive element which receives reflected light from the subject;
a subtractor which subtracts a d.c. component from a sensed signal provided by the light sensitive element, thereby extracting a variation component;
an amplifier which amplifies an output signal of the subtractor;
an A/D converter which implements an A/D conversion for an output signal of the amplifier; and
control means for increasing a level of the d.c. component by a prescribed amount each time an A/D-converted value provided by the A/D converter falls below a prescribed lower level, and for decreasing the electric power supplied to the light emitting element when the level increasing control means continues to increase the level of the d.c. component a predetermined number of times.
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11. An optical measuring device comprising:
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a sensor having a light emitting element which emits light flashes to a subject of detection by being supplied with electric power from a battery for a prescribed duration at prescribed intervals and a light sensitive element which receives reflected light from the subject;
a subtractor which subtracts a d.c. component from a sensed signal provided by the light sensitive element, thereby extracting a variation component;
an amplifier which amplifies an output signal of the subtractor;
an A/D converter which implements an A/D conversion for an output signal of the amplifier; and
control means for decreasing a level of the d.c. component by a first prescribed amount each time an A/D-converted value provided by the A/D converter exceeds a prescribed upper level, for increasing the level of the d.c. component by a second prescribed amount each time the A/D-converted value provided by the A/D converter falls below a prescribed lower level, and for decreasing the electric power supplied to the light emitting element when the level of the d.c. component is decreased and increased alternately a predetermined number of times.
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Specification