Patent Description:
Ultraviolet (UV) sensors are designed to detect the presence of UV radiation. For example, UV sensors may be utilized to detect the presence of radiation in the spectral range of approximately <NUM> to <NUM>.

UV sensors may be useful in many different product applications. For example, UV sensors may be useful in detecting the presence of a flame in a burner of a combustion appliance. Detecting the presence of a flame inside a burner can help safely operate the burner. For instance, if no flame is present in the burner, the burner may be shut down to help prevent unburned fuel from accumulating inside of the burner.

The absolute sensitivity of UV sensors may vary among a batch of new UV sensors. Also, absolute sensitivity of UV sensors tends to degrade over time, depending on usage, temperature and/or other environmental conditions, and other factors. As sensitivity degrades, it may be necessary to re-tune the combustion appliance, adjust safety parameters, and eventually replace the UV sensor, all of which may require a re-commissioning of the combustion appliance. What would be desirable is a technique to help compensate for variations in the sensitivity between UV sensors and/or variations in sensitivity over time.

Such UV sensors are known from <CIT> and <CIT>.

This disclosure relates generally to ultraviolet (UV) sensors, and more particularly to UV sensors for use in combustion appliances. Acccording to the invention, a programmable controller for controlling an ultraviolet (UV) sensor comprising the features of claim <NUM> is disclosed.

Alternatively or additionally to the foregoing, the programmable sensitivity offset circuit may be configured to automatically change the programmable sensitivity offset over the lifetime of the UV sensor.

Alternatively or additionally to any of the embodiments above, the programmable sensitivity offset may be programmed at a time of original manufacturer of the UV sensor.

Alternatively or additionally to any of the embodiments above, the programmable sensitivity offset may be programmed at a time of commissioning of the UV sensor.

Alternatively or additionally to any of the embodiments above, the programmable sensitivity offset circuit may comprise a memory that stores the programmable sensitivity offset tailored to a particular UV sensor.

Alternatively or additionally to any of the embodiments above, the programmable controller may further comprise the memory storing a relationship between a programmable sensitivity offset variable and an elapsed time variable, and the programmable sensitivity offset circuit may be configured to reference the relationship stored in the memory with the elapsed time provided by the timer to identify the programmable sensitivity offset for use in controlling the excitation voltage produced by the excitation voltage generator.

Alternatively or additionally to any of the embodiments above, the programmable controller may further comprise the memory storing a relationship between the programmable sensitivity offset variable, the elapsed time variable and a temperature over time variable, and the programmable sensitivity offset circuit may be configured to reference the relationship stored in the memory with the elapsed time provided by the timer and the temperature provided by the temperature sensor to identify the programmable sensitivity offset for use in controlling the excitation voltage produced by the excitation voltage generator.

Alternatively or additionally to any of the embodiments above, the memory may store a multi-variable relationship between one or more condition variables and a programmable sensitivity offset variable, and the programmable sensitivity offset circuit may be configured to reference the multi-variable relationship stored in the memory with one or more of the condition variables to identify the programmable sensitivity offset for use in controlling the excitation voltage produced by the excitation voltage generator.

Alternatively or additionally to any of the embodiments above, the one or more condition variables may comprise an elapsed time variable.

Alternatively or additionally to any of the embodiments above, the one or more condition variables may comprise a temperature variable.

Alternatively or additionally to any of the embodiments above, the one or more condition variables may comprise an over-voltage variable.

Alternatively or additionally to any of the embodiments above, the one or more condition variables may comprise a cumulative number of conduction events of the UV.

Alternatively or additionally to any of the embodiments above, the relationship between the programmable sensitivity setting offset and the elapsed time variable may be tailored to a particular UV sensor.

In another embodiment, a method of operating an ultraviolet (UV) sensor according to claim <NUM> is disclosed.

Alternatively or additionally to any of the embodiments above, the programmable sensitivity offset may be stored at a time of original manufacture of the UV sensor.

Alternatively or additionally to any of the embodiments above, the programmable sensitivity offset may be stored at a time of commissioning of the UV sensor.

Alternatively or additionally to any of the embodiments above, a relationship between the programmable sensitivity offset and time may be stored, and wherein the excitation voltage provided to the UV sensor is adjusted over the lifetime of the UV sensor based at least in part on the relationship between the programmable sensitivity setting and time.

The above summary of some illustrative embodiments is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The Figures and Description which follow more particularly exemplify these and other illustrative embodiments.

The disclosure may be more completely understood in consideration of the following description in connection with the accompanying drawings, in which:.

The following description should be read with reference to the drawings in which similar structures in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the disclosure.

Certain embodiments of the present disclosure may be found in a system, a method, and/or a non-transitory computer-readable storage medium with an executable program stored thereon for implementing parameter collection operations to obtain critical information regarding actuators used in building control devices. In various embodiments, controller(s) may be configured to direct the operation of actuators included with and/or in building control devices of a building automation system located in or around a building. In this regard, a user may be provided the insight into the overall performance of specific actuators and descriptions of the status of the actuators used in conjunction with the building control devices. This disclosure describes systems, methods, and executable programs that allow an actuator to more easily discover, organize, and diagnose its overall operating status.

Fuel burners such as those found in water heaters, furnaces, boilers, etc. must have some sort of flame sensor for safe operation. The danger resulting from fuel flowing into a combustion space without presence of a flame to burn the fuel is well known. Fuel burners may, therefore, utilize a flame sensor in a fuel valve control to enable opening of a fuel valve in the presence of a flame or conversely, to close the fuel valve in the absence of a flame. Combustion of hydrocarbon fuels produce flames that emit ultraviolet (UV) radiation (e.g., radiation roughly between <NUM> and <NUM>). As such, in some cases, the fuel sensor may be a UV sensor.

<FIG> is a schematic view of an illustrative ultraviolet (UV) sensor <NUM>. In some cases, the UV sensor <NUM> may be a gas discharge tube type UV sensor. The UV sensor <NUM> may include a pair of electrodes, including a cathode <NUM> and an anode <NUM>, and a gas filled chamber <NUM>. The cathode <NUM> and the anode <NUM> of the UV sensor <NUM> may be driven by an excitation voltage provided by an excitation voltage generator <NUM>. In some cases, the excitation voltage generator <NUM> may charge the cathode <NUM> and the anode <NUM> to an excitation voltage. The excitation voltage may be, for example, between <NUM> and <NUM> volts DC, between <NUM> and <NUM> volts DC, between <NUM> and <NUM> volts DC, upwards of <NUM> volts or <NUM> volts or more, or any other suitable voltage.

When UV rays <NUM>, such as those emitted by a flame of a burner of a combustion appliance, are transmitted through the gas filled chamber <NUM>, the incident energy can cause emission of surface electrons from the cathode <NUM> into the gas. The electrons are then accelerated by the electric field between the negatively charged cathode <NUM> to the positively charged anode <NUM>. These electrons collide with molecules of the gas, generating both negative electrons and positive ions. The electrons are attracted to the anode <NUM> and the ions are attracted to the cathode <NUM>, generating secondary avalanche electrons. With sufficient UV rays <NUM>, a gas discharge current may flow between the cathode <NUM> and the anode <NUM> (sometimes referred to as a conduction event), which reduces the excitation voltage between the cathode <NUM> and the anode <NUM>. When the excitation voltage between the cathode <NUM> and the anode <NUM> is reduced, a conduction event can be detected and the UV sensor <NUM> may send a pulse signal. In some cases, the voltage between the electrodes <NUM> and <NUM> may be quenched before the excitation voltage is again applied. When more UV rays <NUM> that are present, the conduction event will tend to occur sooner after the quench than when less UV rays <NUM> are present. Thus, in some cases, the UV sensor <NUM> may produce a series of pulse signals, where the frequency of the pulse signals is related to the emission of the UV rays <NUM> from a flame.

<FIG> is a schematic view of an illustrative combustion appliance <NUM>. The combustion appliance includes a UV sensor <NUM> for monitoring the presence of a flame <NUM> of a burner <NUM>. The combustion appliance <NUM> may include the UV sensor <NUM>, the burner <NUM>, a programmable controller <NUM>, a burner management system <NUM>, and a gas valve <NUM>. In some embodiments, the burner <NUM> can be a fuel-air or fuel-oxygen burner to produce (e.g. generate) the flame <NUM>. For example, burner <NUM> can be used to produce flame <NUM>, which is used to generate heat for use in residential and/or commercial furnaces, hot water boilers, water heaters, and/or any other suitable application.

In some cases, the programmable controller <NUM> may be operatively coupled to the UV sensor <NUM>. The programmable controller <NUM> may include an excitation voltage generator <NUM>, a control circuit <NUM>, and a programmable sensitivity offset circuit <NUM>. In operation, an excitation voltage may be applied between the cathode <NUM> and the anode <NUM> by the excitation voltage generator <NUM>. The UV sensor <NUM> may be positioned to be exposed to the UV rays <NUM> emitted by the flame <NUM>. Similar to <FIG>, the UV rays <NUM> may eventually cause a gas discharge current (i.e. conduction event) to flow between the cathode <NUM> and the anode <NUM>. After a conduction event, the excitation voltage generator <NUM> may have to refresh the excitation voltage provided to the UV sensor <NUM>, sometimes following a quench, to compensate for any reduction in voltage caused by the conduction event. In some cases, the UV sensor <NUM> may send a pulse signal to the control circuit <NUM> in response to a detected conduction event. In other cases, the control circuit <NUM> may include detection circuitry capable of detecting a conduction event of the UV sensor <NUM>.

The programmable sensitivity offset circuit <NUM> may be programmed with a UV sensitivity offset. In some cases, the programmable sensitivity offset circuit <NUM> may provide a programmable sensitivity offset to the control circuit <NUM>, which may use the programmable sensitivity offset to control the excitation voltage provided by the excitation voltage generator <NUM> to the UV sensor <NUM> such that the UV sensor <NUM> operates at a desired UV sensitivity. The programmable sensitivity offset may be set for the UV sensor <NUM> at the factory, set during commissioning of the UV sensor <NUM> in the field, and/or automatically altered over time to help compensate for a degradation in sensitivity of the UV sensor <NUM>. Once the control circuit <NUM> receives the programmable sensitivity offset from the programmable sensitivity offset circuit <NUM>, the control circuit <NUM> may determine, based on the sensitivity offset, that the excitation voltage needs to be raised (or lowered) so that the UV sensor <NUM> operates at a desired UV sensitivity.

In some cases, gas valve <NUM> can be opened to supply gas to the burner <NUM> during a call for heat. However, during a call for heat, if the programmable controller <NUM> indicates to the burner management system <NUM> that the UV sensor <NUM> does not detect the presence of flame <NUM>, the burner management system <NUM> may turn off the gas valve <NUM> to help prevent the buildup of unburnt fuel in the burner <NUM>. In some cases, if the health of the UV sensor <NUM> is determined to be unacceptable by the programmable controller <NUM>, the burner management system <NUM> may also turn off the gas valve <NUM> and extinguish any flame <NUM> until the UV sensor <NUM> can be serviced. In some cases, the burner management system <NUM> can control various aspects of the operation of burner <NUM>, including initial ignition of the burner <NUM> in response to a call for heat, and the termination of the burner at the end of the call for heat. In some cases the burner management system <NUM> may change the firing rate of the burner <NUM> to produce a more intense flame <NUM> or a less intense flame <NUM>.

<FIG> is a schematic block diagram of an illustrative programmable controller <NUM>. In some instances, the programmable controller <NUM> may include an excitation voltage generator <NUM>, a control circuit <NUM>, a programmable sensitivity offset circuit <NUM>, a timer <NUM>, a temperature sensor <NUM>, and/or any other suitable component as desired. As discussed above, the programmable controller <NUM> may be coupled to and control a UV sensor (e.g., UV sensor <NUM>). The excitation voltage generator <NUM> may apply an excitation voltage to the UV sensor in order to detect UV rays emitted by a flame (e.g., flame <NUM>) of a combustion appliance. The UV sensor <NUM> may have a UV sensitivity that reflects the amount of UV rays needed for the UV sensor <NUM> to detect a given UV emission (e.g. incident UV rays required to trigger a conduction event). The UV sensitivity of a particular UV sensor <NUM> may be dependent on many factors including, for example, impurities in the electrodes of the UV sensor, corrosion of the electrodes, the leakage of gas from the gas filled chamber of the UV sensor, the amount of time the UV sensor has been in operation, the cumulative number of conduction events experienced by the UV sensor, the operating temperature experienced by the UV sensor, the number and/or severity of voltage and/or current spikes experienced by the UV sensor, and/or other factors.

<FIG> is a graph showing an illustrative relationship between relative sensor sensitivity and excitation voltage for an example UV sensor. As can be seen, the UV sensitivity of a UV sensor can be highly dependent on the applied excitation voltage. For example, as shown in <FIG>, increasing the excitation voltage by <NUM>% (e.g. from <NUM>% to <NUM>) may increase the sensitivity of the UV sensor by roughly <NUM>% (e.g. from <NUM>% to <NUM>%). Likewise, decreasing the excitation voltage by <NUM>% may decrease the sensitivity of the UV sensor by a similar amount. While a linear relationship is shown in <FIG>, it should be understood that the relationship between excitation voltage and sensitivity may be non-linear. Also, relationships may exist between temperature and sensitivity, time and sensitivity, cumulative number of conduction events experienced by the UV sensor and sensitivity, operating temperature experienced by the UV sensor and sensitivity, cumulative number and/or severity of voltage and/or current spikes experienced by the UV sensor and sensitivity, and other relationships. In some cases, a multi-variable relationship may be derived and stored between UV sensor sensitivity (e.g. sensitivity offset) and multiple different variables. As such, in some cases, given the numerous factors that can affect the UV sensitivity of the UV sensor, the programmable controller <NUM> may be configured to control the excitation voltage applied to the UV sensor such that the UV sensor operates with a desired UV sensitivity (e.g. constant UV sensitivity over time, temperature, etc.).

Turning back to <FIG>, in some cases, the programmable sensitivity offset circuit <NUM> may include a memory <NUM>. The memory <NUM> can be any type of storage medium that can be accessed by the programmable sensitivity offset circuit <NUM> to perform various examples of the present disclosure. For example, the memory <NUM> can be a non-transitory computer readable medium having computer readable instructions (e.g., computer program instructions) stored thereon that are executable by the programmable sensitivity offset circuit <NUM> and/or control circuit <NUM>. The memory <NUM> can be volatile or nonvolatile memory. The memory <NUM> can be removable (e.g., portable) memory, or non-removable (e.g., internal) memory. The memory <NUM> can be random access memory (RAM) (e.g., dynamic random access memory (DRAM) and/or phase change random access memory (PCRAM)), read-only memory (ROM) (e.g., electrically erasable programmable read-only memory (EEPROM) and/or compact-disc read-only memory (CD-ROM)), flash memory, a laser disc, a digital versatile disc (DVD) or other optical storage, and/or a magnetic medium such as magnetic cassettes, tapes, or disks, among other types of memory. Further, although memory <NUM> is illustrated as being located within the programmable sensitivity offset circuit <NUM>, embodiments of the present disclosure are not so limited. For example, memory <NUM> can be located internal to another computing resource (e.g., enabling computer readable instructions to be downloaded over the Internet or another wired or wireless connection).

In some cases, a UV sensitivity offset may be programmed and stored in memory <NUM> during manufacture of the UV sensor. In some cases, the UV sensitivity offset of the UV sensor may be programmed when the UV sensor is commissioned or installed with a burner (e.g., burner <NUM>) in the field. For example, the UV sensor may be compared to a standard UV sensor having a factory calibrated UV sensitivity, and the sensitivity may be adjusted to match the sensitivity of the standard UV sensor. In some cases, the UV sensitivity offset may be automatically altered over time by the programmable sensitivity offset circuit <NUM> to help compensate for a degradation in sensitivity of the UV sensor <NUM>.

In some cases, the memory <NUM> may store a UV sensitivity forecast model. The UV sensitivity forecast model may be supplied with variables such as, operational time, operational temperature, environmental temperature, other operating and atmospheric conditions, operational degeneration due to common damages to UV sensors, such as gas leakage from the gas filled chamber and/or other variables. The programmable sensitivity offset circuit <NUM> may supply the variable to the UV sensitivity forecast model to determine a UV sensitivity offset. The UV sensitivity offset may then be supplied to the control circuit, which may then determine, based on the UV sensitivity offset, an appropriate excitation voltage so that the UV sensor <NUM> operates at a desired UV sensitivity.

During operation, when the UV sensor is exposed to a flame from a burner, the programmable sensitivity offset circuit <NUM> may provide a UV sensitivity offset to the control circuit <NUM>, and the control circuit <NUM> may control the excitation voltage generator <NUM> to produce an excitation voltage that results in a desired UV sensitivity for the UV sensor. In some cases, programmable sensitivity offset circuit <NUM> may reference a relationship between a UV sensitivity offset and elapsed time. When so provided, the programmable sensitivity offset circuit <NUM> may use the timer <NUM> to identify the time that has elapsed since the UV sensor was commissioned, began operation, was installed, etc. The programmable sensitivity offset circuit <NUM> may then reference the relationship between UV sensitivity offset and elapsed time stored in the memory <NUM> and use the identified elapsed time to look-up the corresponding UV sensitivity offset for the UV sensor at that given time. Once the UV sensitivity offset has been identified, the control circuit <NUM> can process the UV sensitivity offset to determine an excitation voltage that must be applied to achieve the desired UV sensitivity. The control circuit <NUM> may use the excitation voltage generator <NUM> to apply the determined excitation voltage to the UV sensor.

According to the invention, the control circuit <NUM> references a relationship between UV sensitivity offset and a temperature over time. The memory <NUM> of the programmable sensitivity offset circuit <NUM> stores a record of the temperature over time. The control circuit <NUM> uses the timer <NUM> and the temperature sensor <NUM> to identify the environmental temperature in which the UV sensor is operating over time. The control circuit <NUM> stores a record of the temperature over time in the memory <NUM>. This may include, for example, a histogram of the number of seconds the UV sensor has experienced each temperature between <NUM> degrees F and <NUM> degrees F or between <NUM> degrees F and <NUM> degrees F or more. The programmable sensitivity offset circuit <NUM> then accesses the record and identify a similar/closest temperature over time scenario to look-up a corresponding UV sensitivity offset for the UV sensor at that given time. Once the UV sensitivity offset has been identified, the control circuit <NUM> can process the sensitivity offset to determine the excitation voltage that must be applied to achieve the desired UV sensitivity. The control circuit <NUM> may then use the excitation voltage generator <NUM> to apply the determined excitation voltage to the UV sensor.

In some cases, the control circuit <NUM> may reference a relationship between UV sensitivity offset and multi -variables. In some cases, the memory <NUM> may store a record of the multi-variables. For example, similar to the example described above, the programmable sensitivity offset circuit <NUM> may use the timer <NUM>, the temperature sensor <NUM> and/or other sensors or conditions to identify an appropriate UV sensitivity offset given the current multi- variable conditions. Once the UV sensitivity offset has been identified, the control circuit <NUM> can process the sensitivity offset to determine the excitation voltage that must be applied to achieve the desired UV sensitivity. The control circuit <NUM> may then use the excitation voltage generator <NUM> to apply the determined excitation voltage to the UV sensor.

In some cases, the control circuit <NUM> may be configured to automatically change the programmable sensitivity offset over the lifetime of the UV sensor. For example, the programmable controller <NUM> may monitor the number of pulse signals received from the UV sensor over time. In some instances, when the UV sensor is operating at a determined excitation voltage, the programmable controller <NUM> may expect to receive a certain number of pulse signals. In some case, the programmable controller <NUM> may determine that the number of pulse signals received is below an expected amount, particularly when it is known that the flame of the burner is firing hot (perhaps confirmed by a technician or a photodetector or the like). In response, the programmable controller <NUM> may identify that the UV sensor is not operating with the desired UV sensitivity. Accordingly, the programmable sensitivity offset circuit <NUM> may change the UV sensitivity offset and store the new UV sensitivity offset in memory <NUM>. The control circuit <NUM> may then use the new UV sensitivity offset to determine the excitation voltage that must be applied to achieve the desired UV sensitivity.

In some cases, the programmable controller <NUM> may also be used to control the operation of a burner (e.g., burner <NUM>). For example, as stated above, the programmable controller <NUM> may monitor the number of pulse signals received from the UV sensor over time. If the programmable controller <NUM> determines that the number of pulses received is below an expected amount, the programmable controller <NUM> may determine that either the health of the UV sensor is unacceptable (e.g., the UV sensor is broken or is non-operational) or the flame that emits the UV rays is low or extinguished. Accordingly, the programmable controller <NUM> may provide instructions to the burner management system (e.g., burner management system <NUM>) to turn off the flow of fuel into the burner, and either extinguish the flame or prevent the buildup of unburnt fuel in the burner if the flame is already extinguished.

<FIG> is a flow chart showing an illustrative method <NUM> of operating an UV sensor. In some cases, the control circuit <NUM> may send an excitation voltage setpoint and enablement to the excitation voltage generator <NUM>. In addition, the excitation voltage generator <NUM> may provide feedback to the control circuit <NUM> signaling reception of the excitation voltage setpoint and enablement. In some cases, the excitation voltage setpoint may have a range of <NUM> and <NUM> volts DC, <NUM> and <NUM> volts DC, <NUM> and <NUM> volts DC, or any other suitable voltage.

In some cases, the excitation voltage generator <NUM> may apply the excitation voltage to a power conditioning and quench control module <NUM>, as shown. The quench timing module <NUM> may identify the timing of each conductive event of the UV sensor and send the timing to the power conditioning and quench control module <NUM>. In some cases, the power conditioning and quench control module <NUM> may temporarily short the electrodes of the UV sensor <NUM> together to refresh the UV sensor <NUM> (quench the UV sensor <NUM>) before re-applying the excitation voltage.

In some cases, when the UV sensor <NUM> experiences a conduction event, a raw signal may be sent to a signal conditioning module <NUM>, which may process the raw signal and send a pulse signal to the programmable controller <NUM> and the quench timing module <NUM>. In some cases, the programmable controller <NUM> may monitor the number of pulse signals received over time. The frequency of the pulse signals may represent the intensity of the UV rays at the UV sensor <NUM>. In some instances, the programmable controller <NUM> may expect to receive a certain amount of pulse signals in a given time when the flame is burning hot. In some cases, the programmable controller <NUM> may determine that the number of pulse signals received is below the expected amount. In some cases, the programmable controller <NUM> may identify that the UV sensor is not operating with the desired UV sensitivity. Accordingly, the programmable controller <NUM> may change the excitation voltage setpoint to increase the UV sensitivity. The programmable controller <NUM> may then expect that the frequency of the conduction events to increase, and thus the excitation voltage may need to be refreshed more frequently. Therefore, and in some cases, the programmable controller <NUM> may send a timing signal to the quench timing module <NUM> that overrides the timing identified by the quench timing module <NUM>. The power conditioning and quench control module <NUM> may then utilize the override timing and the new excitation voltage to coordinate the quench and the application of the new excitation voltage at the appropriate times.

<FIG> is a flow chart showing another illustrative method <NUM> of operating an UV sensor. At step <NUM>, a sensitivity offset may be stored for the UV sensor. In some examples, a programmable controller may be used and the sensitivity offset may be programmed and stored in the programmable controller. In some examples, the programmable sensitivity offset may be stored on the programmable controller when the UV sensor is manufactured. In some examples, the programmable sensitivity offset may be stored on the programmable controller when the UV sensor is commissioned out in the field. In some examples, the sensitivity offset may be unique and tailored specifically for a particular UV sensor. In some examples, the sensitivity offset may be automatically changed over the lifetime of the UV sensor.

At step <NUM>, the excitation voltage provided to the UV sensor may be adjusted based at least in part on the stored programmable sensitivity offset to produce an excitation voltage that results in a desired UV sensitivity for the UV sensor. In some examples, the excitation voltage may be dependent upon the amount of time that has elapsed, and the excitation voltage may be adjusted over the lifetime of the UV sensor. In some cases, the programmable controller may reference a stored relationship between the programmable sensitivity offset and elapsed time. In some examples, the programmable controller may identify the time that has elapsed since the UV sensor was commissioned, began operation, was installed, etc. The programmable controller may then access the stored relationship and use the identified elapsed time to look-up the sensitivity offset for the UV sensor at that given time. Once the sensitivity offset has been identified, the programmable controller can use the sensitivity offset to determine an adjusted excitation voltage that must be applied to achieve the desired UV sensitivity. At step <NUM>, the adjusted excitation voltage may be used to operate the particular UV sensor.

At step <NUM>, it may be determined whether the particular UV sensor is operating at the desired UV sensitivity. In some examples, the programmable controller may monitor the particular UV sensor. If the programmable controller determines that the particular UV sensor is operating at the desired UV sensitivity, method <NUM> may end. However, if the programmable controller determines that the particular UV sensor is not operating at the desired UV sensitivity, the programmable controller may change the programmable sensitivity offset and determine the excitation voltage that must be applied to achieve the desired UV sensitivity. At step <NUM>, the excitation voltage provided to the particular UV sensor may once again be adjusted based at least in part on the new programmable sensitivity offset to produce an excitation voltage that results in the desired UV sensitivity for the particular UV sensor, and method <NUM> may proceed in a similar fashion until the particular UV sensor is operating at the desired UV sensitivity.

Claim 1:
A programmable controller (<NUM>) for controlling an ultraviolet (UV) sensor (<NUM>) that is excited by an excitation voltage, wherein a UV sensitivity of the UV sensor is dependent on the excitation voltage, the programmable controller comprising:
an excitation voltage generator (<NUM>) configured to produce an adjustable excitation voltage for use by the UV sensor;
a timer (<NUM>) for tracking an elapsed time;
a temperature sensor (<NUM>) for tracking a temperature over time;
a programmable sensitivity offset circuit (<NUM>) for use in controlling the UV sensitivity of the UV sensor, the programmable sensitivity offset circuit is configured to use the timer and the temperature sensor and provide a programmable sensitivity offset for the UV sensor based on the environmental temperature in which the UV sensor is operating over time;
a control circuit (<NUM>) operatively coupled to the excitation voltage generator and the programmable sensitivity offset circuit, the control circuit configured to control the excitation voltage generator based at least in part on the programmable sensitivity offset provided by the programmable sensitivity offset circuit to produce the excitation voltage that results in a desired UV sensitivity for the UV sensor.