Conversion Of Properties Of Light To Frequency Counting
In an embodiment, the invention provides a method for measuring properties of light of a photoelectric device. A capacitor is charged through a switch until a first voltage is obtained. After the capacitor is charged to the first voltage, the switch is opened from the capacitor and the capacitor is discharged through a photoelectric device, which conducts current when acted upon by a property of light, until a second voltage is obtained. The capacitor is charged and discharged in the manner previously described until the frequency of the voltage on the capacitor is determined. When the frequency of the voltage on the capacitor is determined, an electrical signal is generated that is proportional to the frequency of the voltage on the capacitor.
1 ) A device comprising:
a photoelectric device;
a charging/discharging device; and
a frequency counter;
wherein the photoelectric device is electrically connected to the charging/discharging device;
wherein the charging/discharging device is electrically connected to the frequency counter;
wherein the photoelectric device converts a property of light into electrical current;
such that the electrical current drawn through the photoelectric device discharges the charging/discharging device;
such that a frequency of a charging and discharging of the charging/discharging device is determined by the frequency counter;
such that an output of the frequency counter is proportional to the frequency of the charging and discharging of the charging/discharging device.
2 ) The device as in claim 1 wherein the charging/discharging device comprises:
a capacitor;
a first reference voltage; and
a second reference voltage;
wherein the capacitor is charged to the voltage of the first reference voltage;
wherein the capacitor is discharged to the voltage of the second reference voltage by the electrical current drawn though the photoelectric device.
3 ) The device as in claim 2 further comprising:
a switch;
wherein the capacitor is charged to the voltage of the first reference voltage when the switch is closed;
wherein the capacitor is discharged to the voltage of the second reference voltage by the electrical current drawn though the photoelectric device when the switch is open.
4 ) The device as in claim 3 further comprising:
a comparator;
wherein the capacitor is charged to the voltage of the first reference voltage when the switch is closed, the switch being closed when a first input of the comparator fall below the voltage of the second reference voltage;
such that the output of the comparator electrically closes the switch;
wherein the capacitor is discharged to the voltage of the second reference voltage by the electrical current drawn though the photoelectric device when the switch is open, the switch being open when the first input of the comparator reaches the voltage of the first reference voltage;
such that the output of the comparator electrically opens the switch;
wherein the second reference voltage is electrically connected to a second input of the comparator.
5 ) The device as in claim 3 wherein the switch is selected from the group consisting of N-FET transistors, P-FET transistors and bipolar transistors.
6 ) The device as in claim 1 wherein the photoelectric device is selected from the group consisting of photodiodes and photocells.
7 ) The device as in claim 1 wherein the property of light is intensity.
8 ) The device as in claim 1 wherein the property of light is frequency.
9 ) The device as in claim 1 wherein the output of the frequency counter is selected from the group consisting of digital signals and analog signals.
10 ) A method for measuring properties of light comprising:
a) charging a capacitor through a switch until a first voltage is obtained on the capacitor;
b) opening the switch from the capacitor when the first voltage is obtained;
c) discharging the capacitor through a photoelectric device that conducts current when acted upon by a property of light until a second voltage on the capacitor is obtained;
d) repeating a, b, and c until the frequency of the voltage presented on the capacitor is determined;
e) creating an electrical signal that is proportional to the frequency of the voltage presented on the capacitor.
11 ) The method of claim 10 wherein the switch is opened by an output of a comparator when a voltage presented on a first input of the comparator is equal to the voltage of a first reference voltage.
12 ) The method of claim 10 wherein the switch is closed by an output of a comparator when a voltage presented on a first input of the comparator falls below a voltage of a second reference voltage.
13 ) The method of claim 10 wherein the frequency of the voltage presented on the capacitor is determined by a frequency counter.
14 ) The method of claim 10 wherein an increase in the frequency of the voltage presented on the capacitor indicates an increase in the electrical current drawn by the photoelectric device.
15 ) The method of clam 10 wherein a decrease in the frequency of the voltage presented on the capacitor indicates a decrease in the electrical current drawn by the photoelectric device.
16 ) A system comprising:
a device wherein the device comprises:
a photoelectric device;
a charging/discharging device; and
a frequency counter;
wherein the photoelectric device is electrically connected to the charging/discharging device;
wherein the charging/discharging device is electrically connected to the frequency counter;
wherein the photoelectric device converts a property of light into electrical current;
such that the electrical current drawn through the photoelectric device discharges the charging/discharging device;
such that a frequency of a charging and discharging of the charging/discharging device is determined by the frequency counter; such that an output of the frequency counter is proportional to the frequency of the charging and discharging of the charging/discharging device.
17 ) The system of claim 16 wherein the charging/discharging device comprises:
a capacitor;
a first reference voltage; and
a second reference voltage;
wherein the capacitor is charged to the voltage of the first reference voltage;
wherein the capacitor is discharged to the voltage of the second reference voltage by the electrical current drawn though the photoelectric device.
18 ) The system of claim 17 further comprising:
a switch;
wherein the capacitor is charged to the voltage of the first reference voltage when the switch is closed;
wherein the capacitor is discharged to the voltage of the second reference voltage by the electrical current drawn though the photoelectric device when the switch is open.
19 ) The system of claim 18 further comprising:
a comparator;
wherein the capacitor is charged to the voltage of the first reference voltage when the switch is closed, the switch being closed when a first input of the comparator falls below the voltage of the second reference voltage;
such that the output of the comparator electrically closes the switch;
wherein the capacitor is discharged to the voltage of the second reference voltage by the electrical current drawn though the photoelectric device when the switch is open, the switch being open when the first input of the comparator reaches the voltage of the first reference voltage;
such that the output of the comparator electrically opens the switch;
wherein the second reference voltage is electrically connected to a second input of the comparator.
20 ) The system as in claim 16 wherein the system is selected from the group consisting of LED displays, computers, flat-panel displays, cell phones and digital cameras.