Range finder of light amount detection type with multi zone resolution
First Claim
1. An optical range finder having a projection unit for projecting optical flux to an object, a photoreceiving unit for receiving the optical flux returned from the object and outputting a detection signal in accordance with a light quantity of the received optical flux, and a circuitry unit for conducting a measurement of a distance to the object based on the detection signal, wherein the circuitry unit comprises:
- a light quantity determination circuit for comparing a signal level of the detection signal with a reference level to carry out binary determination of the light quantity of the returned optical flux;
a reference level setting circuit for switchably supplying a plurality of reference levels to the light quantity determination circuit, the reference levels being preset in correspondence to multiple stages of the distance; and
a control circuit for controlling the reference level setting circuit to supply the reference levels while switching the reference levels so as to enable the light quantity determination circuit to execute a plurality of the binary determination with the supplied reference levels for one measurement, thereby specifying the distance to one of the multiple stages based on the thus obtained plurality of the binary determination.
1 Assignment
0 Petitions
Accused Products
Abstract
An optical range finder has a projection unit for projecting optical flux to an object, a photoreceiving unit for receiving the optical flux returned from the object and outputting a detection signal in accordance with a light quantity of the received optical flux, and a circuitry unit for conducting a measurement of a distance to the object based on the detection signal. In the circuitry unit, a light quantity determination circuit compares a signal level of the detection signal with a reference level to carry out binary determination of the light quantity of the returned optical flux. A reference level setting circuit switchably supplies a plurality of reference levels to the light quantity determination circuit, the reference levels being preset in correspondence to multiple stages of the distance. A control circuit controls the reference level setting circuit to supply the reference levels while switching the reference levels so as to enable the light quantity determination circuit to execute a plurality of the binary determination with the supplied reference levels for one measurement, thereby specifying the distance to one of the multiple stages based on the thus obtained plurality of the binary determination.
11 Citations
16 Claims
-
1. An optical range finder having a projection unit for projecting optical flux to an object, a photoreceiving unit for receiving the optical flux returned from the object and outputting a detection signal in accordance with a light quantity of the received optical flux, and a circuitry unit for conducting a measurement of a distance to the object based on the detection signal, wherein the circuitry unit comprises:
-
a light quantity determination circuit for comparing a signal level of the detection signal with a reference level to carry out binary determination of the light quantity of the returned optical flux;
a reference level setting circuit for switchably supplying a plurality of reference levels to the light quantity determination circuit, the reference levels being preset in correspondence to multiple stages of the distance; and
a control circuit for controlling the reference level setting circuit to supply the reference levels while switching the reference levels so as to enable the light quantity determination circuit to execute a plurality of the binary determination with the supplied reference levels for one measurement, thereby specifying the distance to one of the multiple stages based on the thus obtained plurality of the binary determination. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. An optical range finder having a projection unit for projecting optical flux to an object, a photoreceiving unit for receiving the optical flux returned from the object and outputting a detection signal in accordance with a light quantity of the received optical flux, and a circuitry unit for conducting a measurement of a distance to the object based on the detection signal, wherein the circuitry unit comprises:
-
a light quantity determination circuit for comparing a signal level of the detection signal with a reference level to effect a binary determination of the light quantity of the returned optical flux;
a reference level setting circuit for switchably supplying a plurality of reference levels to the light quantity determination circuit, the reference levels being preset in correspondence to multiple stages of the distance; and
a control circuit for controlling the reference level setting circuit to sequentially supply the reference levels based on an algorithm while switching the reference levels so as to enable the light quantity determination circuit to sequentially execute sessions of the binary determination with the supplied reference levels for one measurement, thereby specifying the distance to one of the multiple stages according to the algorithm based on the sessions of the binary determination, where the algorithm is designed to specify the distance to one of a far zone and a near zone over the multiple stages of the distance at an initial session of the binary determination, then specify the distance to one of a far sub-zone and a near sub-zone within the specified one of the far zone and the near zone at a next session of the binary determination, and specify the distance to one of the multiple stages within the specified one of the far sub-zone and the near sub-zone at a further session of the binary determination. - View Dependent Claims (10, 11, 12)
-
-
13. An optical range finder having a projection unit including a light emitting element for projecting optical flux to an object, a light quantity adjusting unit for provisionally adjusting a light quantity of the projected optical flux, a photoreceiving unit for receiving the optical flux returned from the object and outputting a detection signal in accordance with a light quantity of the received optical flux, and a circuitry unit for conducting a measurement of a distance to the object based on the detection signal, wherein
the circuitry unit comprises: - a light quantity determination circuit for comparing a signal level of the detection signal with a reference level to carry out binary determination of the light quantity of the returned optical flux;
a reference level setting circuit for switchably supplying a plurality of reference levels to the light quantity determination circuit, the reference levels being preset in correspondence to multiple stages of the distance; and
a control circuit for controlling the reference level setting circuit to supply the reference levels while switching the reference levels so as to enable the light quantity determination circuit to execute a plurality of the binary determination with the supplied reference levels for one measurement, thereby specifying the distance to one of the multiple stages based on the thus obtained plurality of the binary determination, and whereinthe light quantity adjustment unit comprises;
a group of parallel resistive elements which are selectively connected in parallel to the light emitting element for forming bypasses of electric currents flowing through the light emitting element to thereby execute a primary adjustment of the light quantity; and
another group of serial resistive elements which are selectively connected in series to the light emitting element for regulating the electric current flowing through the light emitting element to thereby execute a secondary adjustment of the light quantity. - View Dependent Claims (14, 15, 16)
- a light quantity determination circuit for comparing a signal level of the detection signal with a reference level to carry out binary determination of the light quantity of the returned optical flux;
Specification