Patent Description:
Ultraviolet (UV) light has been found to be an effective disinfectant. Of the various UV wavelengths, <NUM> nanometers (<NUM>) has been found to be particularly promising (effective and safe for humans in moderate doses). Currently, UV lights that emit light of this wavelength are only available as gas-discharge excimer lamps. These excimer lamps may degrade over time, resulting in changing electrical characteristics. Furthermore, different excimer lamps may be formed with different electrical characteristics and may operate at different temperatures. These excimer lamps may be used on aircraft, where it is desirable to reduce a total weight and area of the related power supply. <CIT> relates to a discharge lamp lighting apparatus. <CIT> relates to a dielectric-barrier discharge light source.

The invention relates to a system for powering an excimer bulb according to the appended claim <NUM>. Further features of the system are disclosed in the dependent claims.

The system includes a first inductor configured to be coupled to a first terminal of the excimer bulb. The system further includes a first transistor coupled to the first inductor and having an on state configured to allow current to flow through the first inductor and an off state. The system further includes a second transistor configured to be coupled to the first terminal of the excimer bulb and having an on state configured to allow current to flow through the excimer bulb and an off state. The system further includes a controller coupled to the first transistor and the second transistor, and to control operation of the first transistor and the second transistor to power the excimer bulb.

A first resistor is coupled between the first transistor and an electrical ground; and a second resistor is coupled between the second transistor and the electrical ground, wherein the controller is further coupled to the first resistor and the second resistor and is further configured to control operation of the first transistor and the second transistor based on electrical properties detected at the first resistor and the second resistor.

Any of the foregoing embodiments may further include: a second inductor configured to be coupled to a second terminal of the excimer bulb; a third transistor coupled to the second inductor and having an on state configured to allow current to flow through the second inductor and an off state; a fourth transistor configured to be coupled to the second terminal of the excimer bulb and having an on state configured to allow current to flow through the excimer bulb and an off state, wherein the controller is further coupled to the third transistor and the fourth transistor, and to control operation of the third transistor and the fourth transistor to power the excimer bulb.

In any of the foregoing embodiments, the controller is configured to cause the system to power the excimer bulb both symmetrically and asymmetrically.

Any of the foregoing embodiments may further include: a third resistor coupled between the third transistor and the electrical ground; and a fourth resistor coupled between the fourth transistor and the electrical ground, wherein the controller is further coupled to the third resistor and the fourth resistor and is further configured to control operation of the third transistor and the fourth transistor based on electrical properties detected at the third resistor and the fourth resistor.

In any of the foregoing embodiments, the controller is further configured to control a ramp rate, a duty cycle, a frequency, and an amplitude of power provided to the excimer bulb by controlling operation of the first transistor, the second transistor, the third transistor, and the fourth transistor.

In any of the foregoing embodiments, the excimer bulb is configured to operate in a first stage in which the first terminal and the second terminal are charged, a second stage in which an arc is formed from the first terminal to the second terminal, and a third stage in which the excimer bulb discharges, and wherein the controller is further configured to control operation of the first transistor, the second transistor, the third transistor, and the fourth transistor to control an amount of time the excimer bulb is in the first stage, the second stage, and the third stage.

In any of the foregoing embodiments, the first transistor and the second transistor each include at least one of gallium nitride or silicon carbide.

In any of the foregoing embodiments, the first transistor and the second transistor are each N-channel metal oxide semiconductor field effect transistors (MOSFETs).

In any of the foregoing embodiments, the excimer bulb is configured to generate light having a wavelength between <NUM> and <NUM> nanometers (<NUM> thousandths of an inch, or mils, and <NUM> mils).

Also disclosed is a system for powering an excimer bulb. The system includes a first circuit configured to provide power to a first terminal of the excimer bulb. The system further includes a second circuit configured to provide power to a second terminal of the excimer bulb. The system further includes a controller coupled to the first circuit and the second circuit and configured to control operation of the first circuit and the second circuit to power the excimer bulb.

In any of the foregoing embodiments, the first circuit includes: a first inductor configured to be coupled to the first terminal of the excimer bulb; a first transistor coupled to the first inductor and having an on state configured to allow current to flow through the first inductor and an off state; and a second transistor configured to be coupled to the first terminal of the excimer bulb and having an on state configured to allow current to flow through the excimer bulb and an off state, wherein the controller is coupled to the first transistor and the second transistor and is configured to power the excimer bulb by controlling operation of the first transistor and the second transistor.

In any of the foregoing embodiments, the first circuit further includes: a first resistor coupled between the first transistor and an electrical ground; and a second resistor coupled between the second transistor and the electrical ground, wherein the controller is further coupled to the first resistor and the second resistor and is further configured to control operation of the first transistor and the second transistor based on electrical properties detected at the first resistor and the second resistor.

In any of the foregoing embodiments, the second circuit includes: a second inductor configured to be coupled to the second terminal of the excimer bulb; a third transistor coupled to the second inductor and having an on state configured to allow current to flow through the second inductor and an off state; a fourth transistor configured to be coupled to the second terminal of the excimer bulb and having an on state configured to allow current to flow through the excimer bulb and an off state, wherein the controller is further coupled to the third transistor and the fourth transistor, and to control operation of the third transistor and the fourth transistor to power the excimer bulb.

In any of the foregoing embodiments, the second circuit further includes: a third resistor coupled between the third transistor and the electrical ground; and a fourth resistor coupled between the fourth transistor and the electrical ground, wherein the controller is further coupled to the third resistor and the fourth resistor and is further configured to control operation of the third transistor and the fourth transistor based on electrical properties detected at the third resistor and the fourth resistor.

In any of the foregoing embodiments: the first transistor and the second transistor are each N-channel metal oxide semiconductor field effect transistors (MOSFETs); and the first transistor and the second transistor each include at least one of gallium nitride or silicon carbide.

Also disclosed is a system for powering an excimer bulb. The system includes a first circuit having: a first inductor configured to be coupled to a first terminal of the excimer bulb, a first transistor coupled to the first inductor and having an on state configured to allow current to flow through the first inductor and an off state, and a second transistor configured to be coupled to the first terminal of the excimer bulb and having an on state configured to allow current to flow through the excimer bulb and an off state. The system further includes a second circuit having: a second inductor configured to be coupled to a second terminal of the excimer bulb, a third transistor coupled to the second inductor and having an on state configured to allow current to flow through the second inductor and an off state, and a fourth transistor configured to be coupled to the second terminal of the excimer bulb and having an on state configured to allow current to flow through the excimer bulb and an off state. The system further includes a controller coupled to the first transistor, the second transistor, the third transistor, and the fourth transistor and configured to control operation of the first transistor, the second transistor, the third transistor, and the fourth transistor to power the excimer bulb.

Any of the foregoing embodiments may further include: a first resistor coupled between the first transistor and an electrical ground; and a second resistor coupled between the second transistor and the electrical ground, wherein the controller is further coupled to the first resistor and the second resistor and is further configured to control operation of the first transistor and the second transistor based on electrical properties detected at the first resistor and the second resistor.

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the exemplary embodiments of the disclosure, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein. Thus, the detailed description herein is presented for purposes of illustration only and not limitation.

Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Surface shading lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

The present disclosure discloses a dual tapped inductor driver for powering an excimer lamp, such as an excimer lamp that outputs light having a wavelength designed to injure, kill, or destroy pathogens. For example, the wavelength may be between <NUM> and <NUM> nanometers (<NUM> thousandths of an inch, or mils, and <NUM> mils), between <NUM> and <NUM> nanometers (<NUM> mils and <NUM> mils), or about <NUM> nanometers (<NUM> mils). Where used in this context, "about" refers to the referenced value plus or minus <NUM> percent of the referenced value. The driver may provide push-pull balanced drive from a single-ended, low-cost, and relatively small components. These features are desirable as the driver may be located on an aircraft, where weight and space are at a premium. The driver of the present disclosure may be a nonisolated technology that avoids or reduces leakage inductance issues with transformers and allows all components to be simple ground referenced (i.e., all N-channel metal oxide semiconductor field effect transistors (MOSFETs), microcontrollers, and sensors may be simple ground referenced). A microcontroller may provide full digital control of the operating characteristics and protection features, thus providing ideal power signals to the excimer lamps.

Conventional driver topologies are transformer-based, which reduces efficiency and control, and are relatively large in size and weight (relative to the driver of the present disclosure). Without the control, these conventional drivers tend to fail to provide a soft ramp-up, fail to provide protection, and fail to provide current and voltage control. The small size of the driver disclosed herein allows for point-of-load and point-of-use applications mounded directly to the lamp, thus saving weight, reducing cable usage, and improving safety.

Referring now to <FIG>, a system <NUM> for providing power to an excimer lamp <NUM> is shown. The system <NUM> may include a first circuit <NUM> coupled to a first terminal of the excimer lamp <NUM> and a second circuit <NUM> coupled to a second terminal of the excimer lamp <NUM>. The first circuit <NUM> and the second circuit <NUM> may be mirror images of each other, and may together provide a push-pull power signal to the excimer lamp <NUM>. Although various values for the electrical components (e.g., resistance values for resistors and capacitance values for capacitors) are shown, they are for illustrative purposes only, and one skilled in the art will realize that the scope of the present disclosure is not limited by the electrical values provided herein.

Excimer lamps may operate in three stages: (<NUM>) electrodes or terminals of the lamp <NUM> may be charged; (<NUM>) an arc is formed across the excimer lamp <NUM>; and (<NUM>) a discharge occurs across the lamp <NUM>. It is desirable to control the parameters during each of these three stages, and the system <NUM> accomplishes this goal. The first circuit <NUM> may include a first inductor <NUM> that is coupled to the first terminal of the excimer lamp <NUM>. The inductor <NUM> may be charged to create the charging of the terminals of the lamp <NUM> (i.e., stage <NUM>).

The first circuit <NUM> may further include a first transistor <NUM> coupled to the inductor <NUM>. The first transistor <NUM> may include an on state in which current may flow through the first inductor and may further include an off state to prevent such current flow. The first circuit <NUM> may also include a second transistor <NUM> that is coupled to the first terminal of the excimer bulb. The second transistor <NUM> may also include an on state in which current may flow through the excimer bulb and an off state to prevent such current flow.

The first circuit <NUM> may also include a first resistor <NUM> in series with the first transistor <NUM>, and a second resistor <NUM> in series with the second transistor <NUM>. As will be discussed in further detail below, a controller <NUM> may be coupled to the first resistor <NUM> and the second resistor <NUM> and may detect electrical properties of the first resistor <NUM> and the second resistor <NUM> based on such coupling. The controller <NUM> may include a logic device such as one or more of a central processing unit (CPU), an accelerated processing unit (APU), a digital signal processor (DSP), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or any other device capable of implementing logic. In various embodiments, the controller <NUM> may further include any non-transitory memory known in the art. The memory may store instructions usable by the logic device to perform operations as described herein.

The second circuit <NUM> may include a second inductor <NUM> that is coupled to the second terminal of the excimer lamp <NUM>. The second inductor <NUM> may be charged to create the charging of the terminals of the lamp <NUM> (i.e., stage <NUM> above).

The second circuit <NUM> may further include a third transistor <NUM> coupled to the inductor <NUM>. The third transistor <NUM> may include an on state in which current may flow through the second inductor <NUM> and may further include an off state to prevent such current flow. The second circuit <NUM> may also include a fourth transistor <NUM> that is coupled to the second terminal of the excimer lamp <NUM>. The fourth transistor <NUM> may also include an on state in which current may flow through the excimer bulb and an off state to prevent such current flow.

The second circuit <NUM> may also include a third resistor <NUM> in series with the third transistor <NUM>, and a fourth resistor <NUM> in series with the fourth transistor <NUM>. As will be discussed in further detail below, the controller <NUM> may be coupled to the third resistor <NUM> and the fourth resistor <NUM> and may detect electrical properties of the third resistor <NUM> and the fourth resistor <NUM> based on such coupling.

As referenced above, the controller <NUM> may be coupled to and receive electrical signals from the first resistor <NUM>, the second resistor <NUM>, the third resistor <NUM>, and the fourth resistor <NUM>. The controller <NUM> may receive, for example, a current or voltage signal indicating a current or a voltage of the respective resistor. The controller <NUM> may likewise be coupled to each of the transistors <NUM>, <NUM>, <NUM>, <NUM> and may control operation of the transistors <NUM>, <NUM>, <NUM>, <NUM> based on the currently detected electrical properties of the resistors <NUM>, <NUM>, <NUM>, <NUM>. In particular, the controller <NUM> may detect or determine electrical properties that indicate in which of the three stages the system <NUM> is operating, and further indicate a current status of the excimer lamp <NUM>. Based on this detected information (and based on desirable operation of the excimer lamp <NUM>), the controller <NUM> may control operation of the transistors <NUM>, <NUM>, <NUM>, <NUM> to achieve the desired operation of the excimer lamp <NUM>. For example, the current through the first resistor <NUM> may corresponding to an amount of charge that the first inductor <NUM> is receiving during the charging stage, and the current through the second resistor <NUM> may correspond to an amount of current flowing through the excimer lamp <NUM> during the discharge stage.

As opposed to conventional drivers, the system <NUM> may be used to control various characteristics of the excimer lamp <NUM> through all three stages. In particular, the controller <NUM> may control a ramp rate, a duty cycle, a frequency, and an amplitude of power provided to the excimer lamp <NUM> by controlling operation of the transistors <NUM>, <NUM>, <NUM>, <NUM> based on the detected electrical properties. In addition, the system <NUM> may be used to drive multiple types of lamps or bulbs, again which conventional drivers are incapable of achieving. The system <NUM> may drive the excimer lamp <NUM> in either a symmetrical or non-symmetrical fashion. The controller <NUM> may further control power modulation in order to adjust a brightness of the light from the excimer lamp <NUM>. The transistors <NUM>, <NUM>, <NUM>, <NUM> may be formed using at least one of gallium nitride or silicon carbide and may be low-side N-channel MOSFETS.

The ability for the controller <NUM> to detect or measure the currents through the resistors <NUM>, <NUM>, <NUM>, <NUM> allows it to calculate or determine the current flowing through the excimer lamp <NUM>, the boost stage currents, and voltage measurements for breakdown and excitation voltage with respect to a common ground reference. The system <NUM> provides a dual-tapped inductor boost circuit, which allows for control of the excitation of both poles across the excimer lamp <NUM> rather than allowing one pole of the excimer lamp to be passive or reflexive (as with conventional drivers).

The controller <NUM> is designed to have relatively simple interfaces which allows for controlled timing and ramp rate of boosts for ideal strike voltage as well as controlled steady-state operation. Reverse recovery diodes do not require a high voltage rating because they are only protecting against the negative turns ratio voltage during boost charge, and forward conduct during the discharge mode.

Resistance and capacitance (RC) combinations (i.e., the resistor <NUM> and the capacitor <NUM>, along with the corresponding RC components on the second circuit <NUM>) have been added for ramp rate control to set a rise time of the boost. The primary switching transistors <NUM>, <NUM> are low-side and are protected from excessive voltage by turns ratio, avoiding a high-voltage part requirement. The sinking transistors <NUM>, <NUM> may have a slower response rate than the primary switching transistors <NUM>, <NUM>, and may both be turned on together to cause the voltage across the excimer lamp <NUM> to be zero in order to reset the lamp <NUM> or make the system <NUM> safe for handling. In various embodiments, it may be desirable for the primary switching transistors <NUM>, <NUM> to be GaN-based, and the sinking transistors <NUM>, <NUM> to be SiC due to the relatively high voltages experienced therein.

The topology of the system <NUM> leads to a relatively low-cost, safe, and balanced driver that can control all parameters of excimer drive (i.e., strike voltage, ramp rate, current, on-time, duty cycle, etc.). This allows aging, temperature, and other compensation to a relatively vast array of lamp types (i.e., the system <NUM> may be a universal solution as a driver for driving lamps).

On request demand, the controller <NUM> may begin alternating the pairs transistors <NUM>, <NUM>, <NUM>, <NUM> for progressively longer pulses. This results in gradual increase of the amount of boost voltage applied to the terminals of the excimer lamp <NUM> until the arc strike is initiated. The ramp rate of the strike voltage may be sufficiently fast to cause the arc discharge to form, otherwise the result may be charging the lamp <NUM> capacitance model with an excessive voltage and the resulting eventual discharge may degrade aging performance of the lamp <NUM>.

Once the arc strike forms, it ionizes the krypton and chlorine (KrCl) gas in the lamp <NUM> and results in a plasma state for current conduction. As the arc conducts, the current-source nature of the tapped inductor <NUM>, <NUM> helps to sustain the arc without over-voltage and degradation of the lamp. After the plasma state is reached, successive bipolar strikes between the boost stages can be at a lower voltage if the plasma remains in an excited conductive state. This control of both contacts of the lamp <NUM> theoretically allows ideal current-driven longer duration arcs on both phases and improves lamp efficacy. The avoidance of excessive strike voltage is thought to idealize lamp aging, and the current source nature of the boost inductors adapts to changes in capacitance or other lamp properties over temperature and age.

The controller <NUM> may measure the current through each half-wave of operation with the sense resistors <NUM>, <NUM> in the base of the sinking transistors <NUM>, <NUM>. This allows the controller <NUM> to confirm the presence of an arc along with the operational currents relating to the implied intensity. Using this information, and perhaps temperature feedback, the controller <NUM> may adjust the amount of drive current and the frequency for a given operating mode.

Referring now to <FIG> and <FIG>, operation of the system <NUM> of <FIG> is shown. In particular, a chart <NUM> illustrating current values of the various components during a ramp-up period <NUM> and during steady state operation <NUM> is shown. The chart <NUM> illustrates current <NUM> through the boost transistor <NUM> and the boost transistor <NUM>, current through the resistor <NUM> and the resistor <NUM>, through the ground transistor <NUM> and the ground transistor <NUM>, and the voltage across the excimer lamp <NUM>.

Claim 1:
A system for powering an excimer bulb, the system comprising:
a first inductor (<NUM>) configured to be coupled to a first terminal of the excimer bulb (<NUM>);
a first transistor (<NUM>) coupled to the first inductor (<NUM>) and having an on state configured to allow current to flow through the first inductor and an off state;
a second transistor (<NUM>) configured to be coupled to the first terminal of the excimer bulb and having an on state configured to allow current to flow through the excimer bulb and an off state;
a first resistor (<NUM>) coupled between the first transistor and an electrical ground; and
a second resistor (<NUM>) coupled between the second transistor and the electrical ground; and
a controller (<NUM>) coupled to the first transistor, the second transistor, the first resistor, and the second resistor and configured to control operation of the first transistor and the second transistor based on electrical properties detected at the first resistor and the second resistor to power the excimer bulb.