Apparatus and method for sensing distance
The apparatus for sensing a distance from an object includes an emitter, a first receiver, and a second receiver. The emitter emits a light along an emitting direction toward the object. The first receiver is disposed on a side of the emitter and has a first light incident surface, wherein the first receiver receives the light reflected from the object to generate a first signal. The second receiver is disposed between the emitter and the first receiver and has a second light incident surface, wherein the second receiver receives the light reflected from the object to generate a second signal. The first receiver has a first signal-to-distance curve with a first peak, the second receiver has a second signal-to-distance curve with a second peak, and a distance corresponding to the first peak is larger than a distance corresponding to the second peak.
1. An apparatus for sensing a distance from an object, comprising:
an emitter emitting a light along an emitting direction toward the object;
a first receiver having a first light incident surface, the first receiver being disposed on a side of the emitter and receiving the light reflected from the object to generate a first signal; and
a second receiver having a second light incident surface, the second receiver being disposed between the emitter and the first receiver and receiving the light reflected from the object to generate a second signal;
wherein the first receiver has a first signal-to-distance curve with a first peak, the second receiver has a second signal-to-distance curve with a second peak, and a distance corresponding to the first peak is larger than a distance corresponding to the second peak; a distance corresponding to an intersection point of the first signal-to-distance curve and the second signal-to-distance curve is a predetermined distance; a first angle is formed between a normal of the first light incident surface of the first receiver and a normal of a light-exiting surface of the emitter, a second angle is formed between a normal of the second light incident surface of the second receiver and the normal of the first light incident surface of the first receiver, and the first angle and the second angle are determined according to the predetermined distance.
2. The apparatus of claim 1 , wherein the second signal is larger than the first signal when the distance from the object is smaller than the predetermined distance; the second signal is smaller than the first signal when the distance from the object is larger than the predetermined distance.
3. The apparatus of claim 1 , wherein the first angle is between 6° and 8°, and the second angle is between 1° and 3°.
4. The apparatus of claim 1 , wherein a first distance exists between a midpoint of the first light incident surface and a midpoint of the second light incident surface, a second distance exists between the midpoint of the second light incident surface and a midpoint of the emitter, and the first distance and the second distance are determined according to the predetermined distance.
5. The apparatus of claim 4 , wherein the first distance is between 8 mm and 10 mm, and the second distance is between 13 mm and 15 mm.
6. The apparatus of claim 1 , wherein the emitter is an infrared emitter.
7. A method for sensing a distance from an object, comprising:
providing an apparatus comprising a emitter, a first receiver, and a second receiver, wherein the first receiver and the second receiver are disposed on a side of the emitter, the first receiver has a first signal-to-distance curve with a first peak, the second receiver has a second signal-to-distance curve with a second peak, and a distance corresponding to the first peak is larger than a distance corresponding to the second peak;
emitting a light along an emitting direction toward the object by the emitter;
receiving the light reflected from the object to generate a first signal and a second signal by the first receiver and the second receiver, respectively; and
determining the distance from the object or determining whether the object is within a predetermined distance according to the first signal and the second signal; wherein the predetermined distance is a distance corresponding to an intersection point of the first signal-to-distance curve and the second signal-to-distance curve; a first angle is formed between a normal of a first light incident surface of the first receiver and a normal of a light-exiting surface of the emitter, a second angle is formed between a normal of a second light incident surface of the second receiver and the normal of the first light incident surface of the first receiver, and the first angle and the second angle are determined according to the predetermined distance.
8. The method of claim 7 , wherein when the second signal is larger than the first signal, the distance from the object is determined smaller than the predetermined distance; when the second signal is smaller than the first signal, the distance from the object is determined larger than the predetermined distance.