Abstract: A lighting device includes: a circuit board; a first light emitting diode array and a second light emitting diode array; and a driving circuit. The first light emitting diode array and the second light emitting diode array are mounted on the circuit board so as to generate light, the first light emitting diode array is disposed on the circuit board, and the second light emitting diode array is disposed on the circuit board apart from the first light emitting diode array. The driving circuit is mounted on the circuit board so as to generate an electrical signal for driving the first light emitting diode array and the second light emitting diode array, and the driving circuit is disposed between the first light emitting diode array and the second light emitting diode array.

Abstract: Light sources that emit light having enhanced color spectrum characteristics are described. A color metric called the Lighting Preference Index (LPI) is disclosed that enables quantitative optimization of color preference by tailoring the spectral power distribution of the light source. In an embodiment, a lamp includes at least one blue light source having peak wavelength in the range of about 400 nanometer (nm) to about 460 nm, at least one green or yellow-green light source having peak wavelength in the range of about 500 nm to about 580 nm, and at least one red light source having peak wavelength in the range of about 600 nm to about 680 nm, wherein the lamp has an LPI of at least 120.

Abstract: A system and method for converting alternating current from at least two types of electronic ballasts for fluorescent bulbs into direct current for an array of LEDs. The device is assembled such that it can fit into existing fluorescent bulb fixtures. Alternating current from a contemplated electronic ballast can have one of two peak-to-peak voltages and the circuitry of the device will convert either alternating current into approximately the same direct current. In doing so, the array of LEDs is illuminated providing an LED alternative to fluorescent light bulbs.

Abstract: A system to reduce power consumption in a lighting fixture having one or more lamps is provided. The device includes a relay control module, a load control sensor, and a secondary light source. In certain embodiments, the invention includes a power supply to power the secondary light source. In a particularly useful embodiment, the system is retrofitted to standard fluorescent lighting fixtures and uses one or more light emitting diodes as the secondary light source. The system reduces the overall power consumption and attendant lighting costs by substituting a more energy efficient secondary lighting for the main lighting at times when full lighting is not necessary or desired.

Abstract: The invention relates to a dimming light bulb for retrofitting a ceiling or lamp fixture wherever a dimming function can be accessed from the regular light switch.

Abstract: A programmable driver for driving a solid state lighting device includes a processing circuit, a voltage feedback loop and a power stage. The processing circuit is configured to determine a voltage reference signal based on a nominal current setting and a predetermined power limit. The voltage feedback loop is configured to receive the voltage reference signal and to determine a difference between a reference voltage indicated by the voltage reference signal and a drive voltage of the solid state lighting device. The power stage is configured to limit maximum output voltage for driving the solid state lighting device based at least in part on the determined difference between the reference voltage and the drive voltage of the solid state lighting device provided by the voltage feedback loop.

Abstract: In one embodiment a power supply is configured to reuse a single power supply controller to regulate two different output voltages to two voltages including two different voltage values.

Abstract: A lamp assembly provides both instant light through use of an incandescent/halogen light/lamp source and an energy saving type light provided by a compact fluorescent light/lamp source. Both light sources are enclosed within a common envelope or outer bulb. First and second thermal sensors are provided in the lamp envelope at spaced locations to monitor the temperature of the lamp. When the sum of these two temperatures reaches a preselected value, power to the incandescent lamp source is terminated. Alternatively, when the difference these two temperatures reaches a preselected value, power to the incandescent lamp source is terminated.

Abstract: Proposed is a circuit for driving a fluorescent lamp and a light-emitting diode. The circuit may include an inverter; a fluorescent lamp driving branch for driving a fluorescent lamp; a light-emitting diode driving branch for driving a light-emitting diode; a starting branch; and an alternate control branch. By using a simple circuit structure, various embodiments may realize a circuit capable of conveniently and alternately driving a fluorescent lamp and a light-emitting diode.

Abstract: Embodiments of a lamp comprise a light source with a compact fluorescent device and a light-emitting diode device. The lamp can have a circuit with a load element that matches the light-emitting diode device with loading requirements for a dimmer switch that regulates an input power signal to the lamp. The circuit can also comprise a buffer element and sensor component, the combination of which permits selective illumination of the compact fluorescent device and the light-emitting diode device.

Abstract: A method for using an electronic ballast circuit configured to operate a high intensity discharge (HID) lamp. Multiple light emitting diodes (LEDs) are attached to the current output of the electronic ballast circuit, and current is driven from the current output to light said LEDs. Optionally, prior to driving current through the LEDs, the impedance of the current output is sensed; and the current is driven through the LEDs to light the LEDs upon detection of an impedance significantly lower than an impedance characteristic of the HID lamp. Ignition appropriate to ignite the high intensity discharge is not performed when LEDS are attached to the current output. Alternatively, a signal is provided to disconnect the LEDs during a high voltage output for ignition of the high intensity discharge (HID) lamp.

Abstract: A system for generating light flux including a lamp. The lamp having a plurality of light sources for illuminating an area. The light sources include a plurality of light-generating mechanisms at least one of which is different from the remainder. At least one of the light-generating mechanisms includes at least one of a fluorescent light source or an LED light source and at least one of the plurality of light sources having a different color temperature output than another one of the plurality of light sources. A light source controller electrically coupled with the light sources and electrically coupled to a biological spectrum setting to control the color temperature output of the light sources by applying a percentage allocation of each of the light sources. A switch electrically coupled between the lamp and a power supply and arranged to control supply of power to the lamp.

Abstract: A lamp assembly provides both instant light through use of an incandescent/halogen light/lamp source and an energy saving type light provided by a compact fluorescent light/lamp source. Both light sources are enclosed within a common envelope or outer bulb. First and second thermal sensors are provided in the lamp envelope at spaced locations to monitor the temperature of the lamp. When the sum of these two temperatures reaches a preselected value, power to the incandescent lamp source is terminated. Alternatively, when the difference these two temperatures reaches a preselected value, power to the incandescent lamp source is terminated.

Abstract: In various embodiments, a dimmable operating device for the combined operation of a gas discharge lamp and a semiconductor light source is provided. The dimmable operating device may be configured such that only the semiconductor light source is operated in the lower dimming range and only the gas discharge lamp is operated in the upper dimming range, and at the changeover points at which one sort of light source out of the semiconductor light source and the gas discharge lamp is switched off or on, at the same time a jump in power is applied to the other light source out of the semiconductor light source and the gas discharge lamp, with the result that the human eye cannot perceive, or can only perceive with difficulty, the changeover point.

Abstract: A control apparatus for at least one circuit arrangement for operating fluorescent lamps and LEDs. Switching can occur between operation of the fluorescent lamps and LEDs via a control input.

Abstract: The invention relates to a circuit arrangement for operating at least one discharge lamp (FL1) and at least one LED (D5, D6, Dn), wherein the connection of the LEDs has so-called SELV insulation.

Abstract: The invention relates to a gas discharge tube (30) of a type that may be used for example in gas turbine engine (10) ignition systems. The gas discharge tube (30) has an envelope (42) containing a gas therein and the envelope has a pair of spaced electrodes (38, 40) for application of an electric potential difference across the gas. An electromagnetic radiation source (44), such as a deep UV light source, is arranged to emit photons (50) into the envelope (42) so as to initiate ionisation of the gas, thereby reducing the potential difference required to cause electrical conductance between the electrodes. The electromagnetic radiation source, which may comprise light emitting diodes, may be selectively controlled.

Abstract: A lamp tube switching circuit includes a first connector and a second connector for connecting either an LED lamp tube or a fluorescent type lamp tube, a switch module being a mechanical switch including first, second and third switches, a starter and ballast. Each of the first and second switches has a static terminal for connecting with a power supply, and four dynamic terminals for selectively connecting with the static terminal thereof. Different circuits can be configured by adjusting the connection between the static and dynamic terminals, wherein each circuit can drive a selected type of lamp tube to generate light.

Abstract: A lamp tube switch circuit includes a first connector and a second connector for connecting a lamp tube, a power supply, a switch module including at least six switches connected between the power port, the first connector and second connector, a detecting unit connected between the first connector and the second connector, a control unit, a ballast and a starter. The detecting unit detects impedances between the pins of the lamp tube to determine the type of the lamp tube. The control unit is connected to the detecting unit, and operated to have some of the switches to turn one and the others to turn off whereby a drive circuit is formed enabling power from the power supply to flow through the lamp tube to make the lamp tube to generate light.

Abstract: A lamp tube switch circuit supplies power to a selected LED/fluorescent lamp tube connected between first and second connectors and comprises a ballast and a starter. A power supply has positive and negative terminals. A switch module comprises first, second and third switches each having a first end connecting with the positive terminal, fourth and fifth switches each having a first end connecting with the negative terminal and a sixth switch having a first end connecting with the first connector. A button module has six buttons one of which is correspondent to the selected lamp tube. A control unit is connected to the button module, and functions to turn on and turn off the switches with a predetermined mode according the selected lamp tube.

Abstract: A hybrid light source comprises a discrete-spectrum lamp (for example, a fluorescent lamp) and a continuous-spectrum lamp (for example, a halogen lamp). A control circuit individually controls the amount of power delivered to the discrete-spectrum lamp and the continuous-spectrum lamp in response to a phase-controlled voltage generated by a connected dimmer switch, such that a total light output of the hybrid light source ranges throughout a dimming range. The discrete-spectrum lamp is turned off and the continuous-spectrum lamp produces all of the total light intensity of the hybrid light source when the total light intensity is below a transition intensity.

Abstract: A hybrid light source comprises a discrete-spectrum lamp (for example, a fluorescent lamp) and a continuous-spectrum lamp (for example, a halogen lamp). A control circuit individually controls the amount of power delivered to the discrete-spectrum lamp and the continuous-spectrum lamp in response to a phase-controlled voltage generated by a connected dimmer switch, such that a total light output of the hybrid light source ranges throughout a dimming range. The continuous-spectrum lamp is driven by a continuous-spectrum lamp drive circuit, which is operable to conduct a charging current of a power supply of the dimmer switch and to provide a path for enough current to flow through the hybrid light source, such that the magnitude of the current exceeds rated latching and holding currents of a thyristor of the dimmer.

Abstract: Proposed is a circuit for driving a fluorescent lamp and a light-emitting diode. The circuit may include an inverter; a fluorescent lamp driving branch for driving a fluorescent lamp; a light-emitting diode driving branch for driving a light-emitting diode; a starting branch; and an alternate control branch. By using a simple circuit structure, various embodiments may realize a circuit capable of conveniently and alternately driving a fluorescent lamp and a light-emitting diode.

Abstract: A lamp assembly includes a lamp base having power input terminals, a fluorescent lamp connected to the terminals through a manually operated switch that is on an exterior of the lamp base so that when power is supplied to the terminals the fluorescent lamp is selectively powered by manual operation of the switch, and a light emitting diode (LED) inseparably connected to the terminals so that when power is supplied to the terminals the LED is always powered. This arrangement allows the LED to be ON regardless of the operating status of the fluorescent lamp and allows the fluorescent lamp to be turned OFF while the LED remains ON.

Abstract: A lighting system and method combine at least one LED and at least one gas discharge lamp within a common housing. The lighting system includes a control system to dependently operate each LED and each gas discharge lamp during overlapping, non-identical periods of time. In at least one embodiment, the control system can provide light output by activating LEDs during gas discharge preheating operations and thus extend the useful life of each gas discharge lamp. When dimming the lighting system, the control system can reduce current to the gas discharge lamps and one or more gas discharge lamps can be phased out as dimming levels decrease. As dimming levels decrease, one or more of the LEDs can be activated or groups of LEDs can be phased in to replace the light output of the dimmed gas discharge lamps. Thus, the lighting system can reduce power consumption at low dimming levels.

Abstract: A dimmer switch for controlling the intensity of a dimmable screw-in compact fluorescent lamp provides smooth dimming of the fluorescent lamp and prevents flickering of the lamp due to multiple re-strikes. The dimmer switch prevents multiple re-strikes by avoiding multiple firings of a controllably conductive switching device of the dimmer circuit by limiting the high-end light intensity of the fluorescent lamp. Specifically, the dimmer switch limits the length of a conduction interval of the controllably conductive switching device to less than approximately 75% of each half-cycle. The dimmer switch may include a user-accessible adjustment actuator for changing the dimmer switch between an incandescent operating mode and a screw-in compact fluorescent mode.

Abstract: A hybrid light source comprises a high-efficiency lamp, for example, a fluorescent lamp, and a low-efficiency lamp, for example, a halogen lamp. A control circuit individually controls the amount of power delivered to each of the high-efficiency lamp and the low-efficiency lamp, such that a total light output of the hybrid light source ranges throughout a dimming range from a minimum total intensity to a maximum total intensity. The high-efficiency lamp is turned off and the low-efficiency lamp produces all of the total light intensity of the hybrid light source when the total light intensity is below a transition intensity. The low-efficiency lamp is controlled such that the correlated color temperature of the hybrid light source decreases as the total light intensity is decreased below the transition intensity. The hybrid light source is characterized by a low impedance throughout the dimming range.

Abstract: A method of striking a gas discharge lamp involves the steps of generating a high-frequency square-wave voltage having an operating frequency, generating a sinusoidal voltage from the high-frequency square-wave voltage, controlling the operating frequency to a low-end frequency, and increasing the amplitude of the sinusoidal voltage during successive pulse times and then decreasing the amplitude of the sinusoidal voltage towards the low-end amplitude at the end of each of the successive pulse times until the lamp has struck, where the length of each of the successive pulse times being greater than the length of the previous pulse time. A maximum amplitude of the sinusoidal voltage during each pulse time may be greater than a maximum amplitude of the sinusoidal voltage during the previous pulse time.

Abstract: The present invention relates to a light fixture comprising an electrodeless plasma source, said electrodeless plasma source comprises a resonator and a light bulb, said light bulb is operating inside a cavity of a TIR where the TIR lens comprises a metal grid covering at least a part of said TIR lens, the metal grid grounding electromagnetic radiation generated by said electrodeless plasma source. In another embodiment, the light fixture comprises blowing means sending an air stream into the cavity. A further embodiment also comprises at least one LED, which ELPS bulb and the LED are controlled by a control system, which control system performs dimmer control of at least the ELPS and the LED.

Abstract: A lamp assembly includes a lamp base having power input terminals, a fluorescent lamp connected to the terminals through a manually operated switch that is on an exterior of the lamp base so that when power is supplied to the terminals the fluorescent lamp is selectively powered by manual operation of the switch, and a light emitting diode (LED) inseparably connected to the terminals so that when power is supplied to the terminals the LED is always powered. This arrangement allows the LED to be ON regardless of the operating status of the fluorescent lamp and allows the fluorescent lamp to be turned OFF while the LED remains ON.

Abstract: A circuit arrangement for operating an LED and an fluorescent lamp may include a main rectifier; an auxiliary rectifier; an inverter, the output of said inverter having a terminal for connecting the fluorescent lamp; a starting device, wherein its first terminal is coupled to a control electrode of one of the switches of the inverter; a pull-down circuit; and a starting capacitor; wherein the second terminal of the starting device and the second terminal of the pull-down circuit are coupled to the first output terminal of the auxiliary rectifier; wherein the starting capacitor is coupled between the first and the second output terminal of the auxiliary rectifier; and wherein there is arranged in parallel with the starting capacitor a series circuit including a first and a second terminal for the LED and an LED switch, wherein the LED switch has a control electrode, an operating electrode and a reference electrode.

Abstract: A hybrid light source comprises a discrete-spectrum lamp (for example, a fluorescent lamp) and a continuous-spectrum lamp (for example, a halogen lamp). A control circuit individually controls the amount of power delivered to the discrete-spectrum lamp and the continuous-spectrum lamp in response to a phase-controlled voltage generated by a connected dimmer switch, such that a total light output of the hybrid light source ranges throughout a dimming range. The discrete-spectrum lamp is turned off and the continuous-spectrum lamp produces all of the total light intensity of the hybrid light source when the total light intensity is below a transition intensity.

Abstract: A lamp having improved color quality scale, especially at elevated color temperatures, is provided. The light generated by the light-emitting elements of the lamp, when the lamp is energized, has delta chroma values for fifteen color samples of the color quality scale within select parameters. The delta chroma values are measured in the CIE LAB color space.

Abstract: In various embodiments, a dimmable operating device for the combined operation of a gas discharge lamp and a semiconductor light source is provided. The dimmable operating device may be configured such that only the semiconductor light source is operated in the lower dimming range and only the gas discharge lamp is operated in the upper dimming range, and at the changeover points at which one sort of light source out of the semiconductor light source and the gas discharge lamp is switched off or on, at the same time a jump in power is applied to the other light source out of the semiconductor light source and the gas discharge lamp, with the result that the human eye cannot perceive, or can only perceive with difficulty, the changeover point.

Abstract: Provided are a light-source drive circuit substrate and a light source component which can drive a light source with sufficiently high light source characteristics even when environmental temperature greatly changes, and a display apparatus which includes the light source component. A light-source drive circuit (X) according to the present embodiment includes a controller (C) configured to drive a first light source (L1) and a second light source (L2) having at least one light source characteristics higher than those of the first light source (L1) when the environmental temperature is equal to or below a reference temperature. The controller (C) includes a selector (10) which selects a first driver (D1) for driving the first light source (L1) when the environmental temperature goes above the reference temperature, and selects a second driver (D2) for driving the second light source (L2) when the environmental temperature becomes equal to or below the reference temperature.

Abstract: A fluorescent or light emitting diode-based system for generating light flux. The system comprises a lamp comprising at least one light source for illuminating an area. At least one of the at least one light source is selected from the group comprising at least one of a fluorescent light source or an LED light source. The lamp also comprises a light source controller electrically coupled with the light source and arranged to control the spectral output of the light source. The lamp also comprises a power supply and a switch electrically coupled between the lamp and the power supply and arranged to control the supply of power from the power supply to the lamp.

Abstract: A lamp having improved color quality scale is provided. The lamp has a light-transmissive envelope and a phosphor layer comprising a first phosphor and a second phosphor wherein the first phosphor has an emission band with a maximum between 590 nm and 670 nm and the second phosphor has an emission band with a maximum between 520 nm and 570 nm. The light generated by the phosphor layer, when the lamp is energized, has delta chroma values for fifteen color samples of the color quality scale within select parameters. The delta chroma values are measured in the CIE LAB color space.

Abstract: A switchable compact fluorescent lamp with an L.E.D. added to the center of the top of the compact fluorescent lamp plastic electronic encasement housing. The L.E.D. can be switched on with the fluorescent on or switched to be on by itself with the fluorescent off. The lamp can also be switched to a battery and or capacitor power backup for the L.E.D. when the power goes off.

Abstract: A non-linear test load is provided for calibrating a plasma system. The test load is a substrate for modeling the electrical characteristics of the plasma such that multi frequency testing can be performed in the absence of a plasma reaction. An exemplary substrate includes a first semiconductor junction for providing a non-linear response to the multi-frequency RF source provided from the anode. The first semiconductor junction exhibits a first capacitance for modeling a first plasma sheath of the anode. A plasma component is responsive to the first semiconductor junction and exhibits a resistance for modeling a resistance of the plasma, an inductance for modeling an inductance of the plasma, and a gap capacitance for modeling capacitance of the plasma.

Abstract: An apparatus for protecting an integrated circuit is applied to an electrical apparatus having a control unit. The control unit is used for controlling the integrated circuit and the protecting apparatus. The protecting apparatus includes a power input terminal, a power output terminal, and a control terminal. The power input terminal is used for receiving a power, and the power output terminal is used for outputting the power to the integrated circuit. The control terminal is used for receiving a control voltage of the control unit. When the control unit is at the power on mode, the control unit outputs the control voltage of a first level to prevent the power being input to the integrated circuit. Over a predetermined period of time, the control unit outputs the control voltage of a second level, so that the power can be input to the integrated through the protecting apparatus.

Abstract: A multi-flash strobe light pattern is superimposed on each individual light pulse produced by an incandescent lamp to provide a warning signal of enhanced visibility in a particulate laden ambient environment. The first pulse of each multi-flash strobe pattern is delayed for a time period, subsequent to energization of the incandescent lamp, which is equal to at least 80% of the time required for the incandescent lamp to achieve its maximum light output intensity.

Abstract: An electrical terminal block for a high wattage high intensity projection lamp, and use thereof. The electrical terminal block is connected to an electrical power supply and has an orifice for plug-in of cable that forms part of such a lamp. The terminal block reduces premature lamp failure.

Abstract: The intensity of each lamp which illuminates an object at an inspection station is controlled by controlling driving voltage applied to a power supply which supplies electrical power to the lamp. A phototransistor is used to sense the intensity of the lamp through an optical fiber. The sensor is followed by a digitally-controlled, variable gain circuit whose output is fed to an A-D converter. A microprocessor analyzes the digital signal from the A-D converter and corrects the driving voltage to the power supply to keep the intensity output of the lamp constant, as seen by a camera of a machine vision system. In this way, feedback corrects for a degraded lamp output due to aging. Preferably, the control of the level of lamp intensity can be changed from a remote system console of the machine vision system to reduce the need for access to internal parts, thereby reducing the probability that human error may cause a malfunction.

Abstract: In accordance with the invention the circuitry arrangement comprises a central unit (5) and a plurality of peripheral units, such as control apparatuses for lamps, connected with the central unit via a data bus. These peripheral units are each connected with the data bus (1) via a coupling unit (3), each coupling unit (3) having a receiving branch for the transfer of information from the central unit (5) to the peripheral unit, and a transmission branch for the transfer of information from the peripheral unit to the central unit (5). Here, the central unit (5) sends out information in the form of a modulated a.c or pulse voltage onto the data bus. The transmission branch applies information to the data bus (1) in that the output resistance of the transmission branch is varied. Because the receiving branch in the coupling unit (3) is continuously active and the transmission branch is inactive in the case of non-sending operation, at most a very small return current is consumed in the coupling unit (3).

Abstract: The invention relates to a light calibration system consisting of a compact LED source with feedback control of intensity. The source is positioned in the focal plane of the microscope objective and produces flat-field illumination of up to 31 microwatts. The source can be easily used to determine the performance of microscope optics and camera response. It can also be used as a standard light source for calibration of experimental systems. Selectable light intensities are produced by controlling the LED input power via a feedback circuit consisting of a photodiode that detects output light intensity. Spectral coverage extends between 550 nm and 670 nm using green, yellow and red LEDS mounted side-by-side and which are individually selected. The LED chips are encapsulated in plastic diffusers which homogenize the light, and a flat field of illumination is obtained through a thin 1 mm diameter aperture positioned directly over each chip.

Abstract: An intermittent low intensity light source that is switched on by a drive signal is enhanced by a high intensity light source. The high intensity light source is coupled with the low intensity light source so that at least some light from both sources is projected in a desired direction. The high intensity light source has a brightness or intensity that significantly exceeds that of the low intensity light source. A pulse power source is connected to the high intensity light source and made responsive to the drive signal for pulsing the high intensity light source to emit a brief light pulse before the low intensity light source achieves any substantial precentage of its peak intensity, the light pulse occurring in such close time proximity to the peak intensity of the low intensity light source that persistence of vision in the human eye causes the two light sources blend together visually.

Abstract: A lighting system for a suspended ceiling comprises a central high-frequency power source feeding a plurality of power conditioning units permanently wired-in and mounted in various locations on the permanent ceiling above the suspended ceiling. Each such power conditioning unit provides a power-limited Class-3 high-frequency voltage at an output receptacle and is operable to power a special fluorescent lighting fixture by way of a light-weight flexible two-wire detachable connect cord. Special fluorescent lighting fixtures are mounted in the suspended ceiling, with each such lighting fixture being powered from a power conditioning unit mounted somewhere nearby on the permanent ceiling above.

Abstract: A flash tube is provided for producing successive high intensity bursts of light, and a pulse producing device is provided for supplying a train of high voltage pulses for energizing repeatedly the flash tube. An impedance matching arrangement is provided and includes a first unidirectional device which couples the output of the alternator to the pulse producing device for energizing it periodically during half cycles of the alternating current output of the alternator. The arrangement also includes a second unidirectional device which the output of the alternator to an auxiliary lighting device to energize it during alternate half cycles of the alternator. As a result, the alternator supplies lower instantaneous current to both loads at a favorable operating characteristic of the source.

Abstract: A discharge lamp comprises an arc tube for high pressure discharge and a discharge gap for discharging until restarting the arc tube. The discharge gap being electrically connected in parallel to the arc tube in an outer bulb. A normally opened temperature responsive switch means is connected in series to the discharge gap and a series of the discharge gap and the temperature responsive switch means is connected in parallel to the arc tube.

Abstract: Ballasting for a fluorescent lamp is provided by one or more incandescent lamps connected in series between the line voltage source and the fluorescent lamp. Lamp operation is initiated by a triggering pulse applied to a conductive member placed adjacent the fluorescent lamp. In one embodiment, a plurality of incandescent lamps are connected in parallel and are selectively gated into the circuit depending upon exposure requirements for the lamp.