Distance measuring method and distance measuring apparatus
AssigneeSony Corporation
InventorsAtsushi Yokoyama, Takayuki Yoshigahara
Life of this patent
Estimating the term…
Abstract
Two photodiodes are disposed side by side in the direction in which the slit light reflected from the object to be measured moves. One photodiode 1 of the two photodiodes receives the reflected slit light for a longer period than the other photodiode 2. When neither of the two photodiodes receive the slit light reflected from the object to be measured but both receive the same bias light, even if very weak noise light is incident from the outside or the characteristics of the photodiodes slightly differ, a higher light current flows through the photodiode 1 than through the photodiode 2, making the output of the clock-type comparator 7 stable in the initial state. This allows distance measurement to be always performed stably.
Claims14
A distance measuring method comprising the steps of:
- scanning a surface of an object to be measured with slit light;
- receiving the slit light reflected from said object to be measured on an imaging plane comprising a plurality of cells each of which has a pair of photosensors disposed side by side in the direction in which the reflected slit light moves, one of said pair of photosensors being enabled to collect light from said reflected slit light for a longer period than the other;
- providing electronic signals to enable said photosensors to collect light, wherein one of said pair of photosensors is enabled to collect light for a longer period than the other of said pair of photosensors;
- comparing the magnitudes of the light currents output from said pair of photosensors in each cell;
- detecting the time at which said reflected slit light moves from one of said pair of photosensors to the other according to the result of the comparison, said time being regarded as the time at which said reflected slit light passes said plurality of cells;
- and
- measuring the position of said surface of said object from the times when said reflected slit light passes said plurality of cells forming said imaging plane.
A distance measuring apparatus comprising:
- means for emitting slit light to an object to be measured and for scanning a surface of said object with said slit light;
- means for receiving the slit light reflected from said object on an imaging plane comprising a plurality of cells, each cell including a pair of photosensors which are disposed side by side in the direction in which the reflected slit light moves and one of which is electronically enabled to receive said reflected slit light for a longer period than the other, and a comparator for comparing the magnitudes of the light currents output from said pair of photosensors;
- means for detecting the time at which the relationship between the magnitudes of the light currents output from said pair of photosensors is reversed;
- and
- means for measuring the position of said surface of said object according to said time for each cell.
A distance measuring apparatus comprising:
- a light source and optical system which emits slit light to an object to be measured and scans a surface of said object with said slit light;
- an photosensitive array which receives the slit light reflected from said object on a plurality of cells, each cell including a pair of photosensors which are disposed side by side in a direction in which the reflected slit light moves;
- a circuit for independently enabling each of said photosensors to detect light, wherein one of said pair of photosensors is enabled for a longer period than the other;
- a comparator associated with each said cell which compares the light detected by each of said pair of photosensors and indicates a time at which the photosensor of said pair which is receiving more light than the other changes;
- a memory which stores said indicated times;
- and
- a processor which determines the position of said surface of said object according to said stored times for each cell.
Dependencies are inferred from the claim text.