Raindrop detection apparatus and method
AssigneeDenso Corporation
InventorJunichi Ishikawa
Life of this patent
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Abstract
A raindrop detection apparatus has an amplifier circuit, including a plurality of resistors and resistor selection switches. The control circuit performs the first adjustment to an output of the amplifier circuit, roughly adjusting the output to a target value. The first adjustment is made by selecting one of or a combination of resistors. The control circuit then performs the second adjustment to the output, closely adjusting the output to the target value. The second adjustment is made by adjusting a driving instruction signal, which actually adjusts a light emitting device driving current. These adjustments are performed after an IG switch and an AUTO mode switch of a wiper switch are turned on.
Claims13
A raindrop detection apparatus comprising:
- a light emitting device which emits light toward a windshield where a raindrop may be present;
- a light emitting device driving section supplying a power to the light emitting device;
- a photoreceptor which receives reflected light from the windshield, emitted from the light emitting device;
- an amplifying section amplifying a signal from the photoreceptor;
- and
- a control section detecting an amount of the raindrop on the windshield based on an output from the amplifying section as well as controlling operations of the light emitting device driving section and the amplifying section;
- wherein the control section includes:
- a first adjustment means which adjusts the output from the amplifying section to a predetermined target value by varying amplifying gains of the amplifying section, and
- a second adjustment means which adjusts the output to the target value by varying a power supplied from the light emitting device driving section to the light emitting device after the adjustment by the first adjustment means;
- and
- wherein the output adjustments performed by the first and the second adjustment means are programmed to execute output adjustment operations under a condition in which no raindrop or foreign substance is present on the windshield, the condition in which no raindrop or foreign substance is present on the windshield being created by mandatorily wiping the windshield.
A raindrop detection method comprising:
- setting up a target value indicative of no raindrop or foreign substance on a windshield, the target value being set up after the windshield is mandatorily wiped so that no raindrop or foreign substance is on the windshield;
- changing amplifying gains of an amplifying section where a signal from the photoreceptor is amplified so that an output from the amplifying section becomes close to the target value;
- and
- changing a power supply to the light emitting device so that the output from the amplifying section becomes still closer to the predetermined target value.
A raindrop detection method for a wiper system mounted on a vehicle having an ignition switch and a windshield, the wiper system including a raindrop sensor, a wiper and a wiper driving unit which is automatically operable in response to an output of the raindrop sensor that detects raindrops, the method comprising:
- mandatorily operating the wiper driving unit in response to each turn-on of the ignition switch thereby to wipe the windshield irrespective of the output of the raindrop sensor when the wiper driving unit is in a state of readiness to automatically operate the wiper;
- adjusting the output of the raindrop sensor to a predetermined target value following mandatorily operating the wiper driving unit;
- and
- automatically operating the wiper driving unit in response to the output of the raindrop sensor indicative of raindrops after the adjustment of the output of the raindrop sensor is completed.
A raindrop detection apparatus comprising:
- a light emitting device which emits light toward an object where a raindrop may be present;
- a light emitting device driving section supplying a power to the light emitting device;
- a photoreceptor which receives reflected light from the object, emitted from the light emitting device;
- an amplifying section amplifying a signal from the photoreceptor;
- and
- a control section detecting an amount of the raindrop on the object based on an output from the amplifying section as well as controlling operations of the light emitting device driving section and the amplifying section,
- wherein the control section includes:
- a rough adjustment means which adjusts the output from the amplifying section to a first value which is at least close to a predetermined target value by varying amplifying gains of the amplifying section, and
- a fine adjustment means which adjusts the output to a second value which is closer than the first value to the target value by varying a power supplied from the light emitting device driving section to the light emitting device after the adjustment by the rough adjustment means.
Dependencies are inferred from the claim text.