Distance measurement system
First Claim
1. An active distance measurement system comprising:
- a light source for emitting a series of light pulses toward an object at a distance to be measured;
a position sensing detector for detecting the light pulses reflected from the object and outputting signals, each signal corresponding to a position where a light pulse reflected from the object is detected;
an arithmetic unit outputting signals corresponding to the distance to the object in response to the signals output from said position sensing detector;
an integrating capacitor set to a reference voltage before emission of the series of light pulses, said capacitor being charged or discharged by signals output from said arithmetic unit;
a distance detection unit for detecting the distance to the object based on a voltage of said capacitor present after emission of the series of light pulses;
a temperature sensing unit for measuring ambient temperature; and
a control unit for controlling said distance measurement system to adjust charging and discharging operations of said capacitor by said arithmetic unit in response to the ambient temperature measured by said temperature sensing unit to offset a temperature dependency of the voltage of said capacitor present after emission of the series of light pulses.
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Accused Products
Abstract
In a distance measure system, an autofocus integrated circuit is furnished with a power source voltage and an integrating capacitor is preliminarily charged to a reference voltage VREF. A temperature sensor detects ambient temperature. Thereafter, under the control of a CPU, an infrared emitting diode emits pulsed infrared light and the integrating capacitor discharges by a voltage level corresponding to a distance to an object to be measured. On the occasion of integration by an integrating unit of a signal output from an arithmetic unit, discharging of the integrating capacitor is performed multiple times, corresponding to the ambient temperature measured by a temperature sensor.
19 Citations
6 Claims
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1. An active distance measurement system comprising:
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a light source for emitting a series of light pulses toward an object at a distance to be measured;
a position sensing detector for detecting the light pulses reflected from the object and outputting signals, each signal corresponding to a position where a light pulse reflected from the object is detected;
an arithmetic unit outputting signals corresponding to the distance to the object in response to the signals output from said position sensing detector;
an integrating capacitor set to a reference voltage before emission of the series of light pulses, said capacitor being charged or discharged by signals output from said arithmetic unit;
a distance detection unit for detecting the distance to the object based on a voltage of said capacitor present after emission of the series of light pulses;
a temperature sensing unit for measuring ambient temperature; and
a control unit for controlling said distance measurement system to adjust charging and discharging operations of said capacitor by said arithmetic unit in response to the ambient temperature measured by said temperature sensing unit to offset a temperature dependency of the voltage of said capacitor present after emission of the series of light pulses. - View Dependent Claims (2, 3, 4, 5)
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6. An active distance measurement system comprising:
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a light source for emitting a series of light pulses toward an object at a distance to be measured;
a position sensing detector for detecting the light pulses reflected from the object and outputting signals, each signal corresponding to a light pulse and a position on the position sensing detector where a light pulse reflected from the object is detected;
an integrating capacitor set to a reference voltage before emission of the series of light pulses, said capacitor being charged or discharged in a first integration by signals output from said position sensing detector and respectively corresponding to the light pulses;
a distance detection unit detecting the distance to the object by discharging or charging said capacitor at a constant rate to the reference voltage, after emission of the series of light pulses;
a temperature sensing unit for measuring ambient temperature before emission of the series of light pulses; and
a control unit receiving the ambient temperature measured and controlling said distance measurement system by changing at least one of the number of the light pulses emitted in the series of light pulses, duration of the light pulses emitted in the series of light pulses, and the constant rate of discharging or charging of said capacitor, after emission of the series of light pulses, in response to the ambient temperature measured.
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Specification