Wireless sensor having a controllable photosensitive circuit
View Patent ↗A wireless sensor for measuring a light intensity comprises a photosensitive circuit that can be disabled, for example, to conserve battery power. The wireless sensor may further comprise a wireless transmitter for transmitting wireless signals, a controller and a battery for powering the photosensitive circuit, the wireless transmitter, and the controller. The photosensitive circuit may generate a light intensity control signal in response to the light intensity. The photosensitive circuit may include a photosensitive diode for conducting a current having a magnitude responsive to the light intensity. The controller may be configured to disable the photosensitive circuit by opening a controllable switch that is coupled in series with the photosensitive diode. The controller may enable the photosensitive circuit, subsequently sample the light intensity control signal at a sampling period, and then disable the photosensitive circuit after the light intensity control signal has been sampled.
1. A wireless sensor for measuring a light intensity, the sensor comprising:
a photosensitive circuit configured to generate a light intensity control signal in response to the light intensity;
a wireless transmitter configured to transmit wireless signals;
a controller coupled to the photosensitive circuit and the wireless transmitter, the controller configured to transmit a wireless signal in response to the light intensity control signal; and
a battery for powering the photosensitive circuit, the wireless transmitter, and the controller;
wherein the controller is configured to disable the photosensitive circuit so that the photosensitive circuit does not draw current from the battery.
2. The sensor of claim 1 , wherein the photosensitive circuit comprises a photosensitive diode configured to conduct a photosensitive diode current having a magnitude responsive to the light intensity, the magnitude of the light intensity control signal responsive to the magnitude of the photosensitive diode current.
3. The sensor of claim 2 , wherein the photosensitive circuit further comprises a controllable switch coupled in series with the photosensitive diode, the photosensitive diode configured to conduct the photosensitive diode current when the controllable switch is closed, the controller coupled to the controllable switch for opening the controllable switch so that the photosensitive diode does not conduct the photosensitive diode current and the photosensitive circuit is disabled.
4. The sensor of claim 3 , wherein the controller is configured to periodically sample the light intensity control signal at a sampling rate and close the controllable switch for a portion of the time between each sample.
5. The sensor of claim 4 , wherein the controller is configured to determine when it is nighttime in response to the light intensity control signal and decrease the sampling rate during the nighttime.
6. The sensor of claim 3 , wherein the photosensitive circuit further comprises a transimpedance amplifier coupled between the photosensitive diode and the controller, the transimpedance amplifier configured to generate the light intensity control signal in response to the photosensitive diode current.
7. The sensor of claim 1 , wherein the controller is configured to enable the wireless transmitter and to transmit a wireless signal if the light intensity changes by a predetermined amount.
8. The sensor of claim 1 , wherein the controller is configured to enable the photosensitive circuit and subsequently sample the light intensity control signal at a sampling period, the controller further configured to disable the photosensitive circuit after the light intensity control signal has been sampled so that the photosensitive circuit draws current from the battery for a small time period during each sampling period.
9. A wireless sensor for measuring a light intensity, the sensor comprising:
a photosensitive circuit comprising a photosensitive diode configured to conduct a photosensitive diode current having a magnitude responsive to the light intensity, the photosensitive circuit further comprising a controllable switch coupled in series with the photosensitive diode, the photosensitive diode configured to conduct the photosensitive diode current when the controllable switch is closed;
a wireless transmitter configured to transmit wireless signals; and
a controller coupled to the photosensitive circuit and the wireless transmitter, the controller configured to transmit a wireless signal in response to the photosensitive diode current;
wherein the controller is configured to disable the photosensitive circuit by opening the controllable switch so that the photosensitive diode is not able to conduct the photosensitive diode current.
10. The sensor of claim 9 , wherein the photosensitive circuit is configured to generate a light intensity control signal having a magnitude that is responsive to the magnitude of the photosensitive diode current.
11. The sensor of claim 10 , wherein the controller is configured to periodically sample the light intensity control signal at a sampling rate and close the controllable switch for a portion of the time between each sample.
12. The sensor of claim 11 , wherein the controller is configured to determine when it is nighttime in response to the light intensity control signal and decrease the sampling rate during the nighttime.
13. The sensor of claim 10 , wherein the photosensitive circuit further comprises a transimpedance amplifier coupled between the photosensitive diode and the controller, the transimpedance amplifier configured to generate the light intensity control signal in response to the photosensitive diode current.
14. The sensor of claim 9 , wherein the controller is configured to enable the photosensitive circuit and subsequently sample the light intensity control signal at a sampling period, the controller further configured to disable the photosensitive circuit after the light intensity control signal has been sampled so that the photosensitive diode conducts the photosensitive diode current for a small time period during each sampling period.
15. A wireless sensor for measuring a light intensity, the sensor comprising:
a photosensitive circuit configured to generate a light intensity control signal in response to the light intensity;
a wireless transmitter configured transmit wireless signals; and
a controller coupled to the photosensitive circuit and the wireless transmitter, the controller configured to transmit wireless signals in response to the light intensity control signal;
wherein the controller is configured to enable the photosensitive circuit and subsequently sample the light intensity control signal at a sampling period, the controller further configured to disable the photosensitive circuit after the light intensity control signal has been sampled.
16. The sensor of claim 15 , wherein the photosensitive circuit comprises a photosensitive diode configured to conduct a photosensitive diode current having a magnitude responsive to the light intensity, the magnitude of the light intensity control signal responsive to the magnitude of the photosensitive diode current.
17. The sensor of claim 16 , wherein the photosensitive circuit further comprises a controllable switch coupled in series with the photosensitive diode, the photosensitive diode configured to conduct the photosensitive diode current when the controllable switch is closed, the controller coupled to the controllable switch for opening the controllable switch so that the photosensitive diode does not conduct the photosensitive diode current and the photosensitive circuit is disabled.
18. The sensor of claim 15 , wherein the controller is configured to transmit wireless signals using a variable transmission rate that is dependent upon the light intensity.
19. The sensor of claim 18 , wherein the variable transmission rate is also dependent upon a dynamic change in the light intensity.
20. The sensor of claim 15 , further comprising:
a battery for powering the photosensitive circuit, the wireless transmitter, and the controller;
wherein the photosensitive circuit is configured to draw current from the battery for a small time period during each sampling period.