摘要:
High-pressure discharge lamps may explode at the end of their life. In order to be able to predict an explosion, the gradient of the operating voltage is evaluated. If a risk of explosion is detected, the lamp operation is interrupted.
摘要:
High-pressure discharge lamps may explode at the end of their life. In order to be able to predict an explosion, the gradient of the operating voltage is evaluated. If a risk of explosion is detected, the lamp operation is interrupted.
摘要:
A switched mode power supply (SNT) is coupled to a source of d-c energy (U.sub.Batt) and provides electrical energy to a lamp within widely varying limits. The switching conditions of the switched mode power supply are controlled by an operation control circuit (ADD) which has a current sensing resistor, serially connected to the lamp, to provide a lamp current signal, and a voltage divider (R2, R3) connected across the lamp to sense lamp voltage and provide a lamp voltage signal. The lamp current signal and the lamp voltage signal are added, compared in a comparator formed by an operational amplifier (IC2-A), with respect to a reference setting power level, and the output signal from the comparator is coupled back to the switched mode power supply to control the switching rate thereof, based on the instantaneous lamp current and lamp voltage. Excess voltage can be compensated by providing either an active semiconductor switching network (T1, T2, FIG. 3) or a passive semiconductor switch (ZD), which affects the added current-voltage signal applied to the comparator (IC2-A).
摘要:
To operate a discharge lamp, and more particularly a low-power high-pressure discharge lamp, only in quiet or stable lamp operation, a microprocessor (MC) is provided which establishes a test phase of limited time duration during which the frequency of operation of the lamp is varied by frequency modulation within a predetermined range. Lamp operation is monitored, for example by deriving a test voltage across a coupling capacitor (C6) receiving lamp current. If the monitored voltage, which is representative of lamp operation, shows that the lamp operates quietly and stably, the then pertaining frequency is stored by the microprocessor and, after the test phase is finished, the lamp is operated within a frequency window formed by the largest number of contiguous modulation frequencies which are suitable for, or result in, stable lamp operation. The test phase is carried out repetitively, at least upon each energization of the lamp, so that different operating characteristics of the lamp (e.g. due to changes in temperature, aging, or the like) are compensated.
摘要:
To provide for effective control of a discharge lamp, typically, a sodium gh pressure discharge lamp, which operates in two phases, namely, a power pulse phase, followed by a holding phase, without extensive and complex electronic circuitry, two individual oscillator systems are provided, one for each phase; the oscillator systems include a first power burst oscillator formed as a first half bridge by two transistors (T1, T2), and an individual connecting current limiting inductance (L1) to the lamp (E), and a second oscillator including a two-transistor second half bridge (T3, T4) and an individual current limiting inductance (L2) coupled to the lamp. The respective oscillators are controlled, in a closed control loop, by a burst generator (BG) and a holding pulse generator (SG), each of which provide their signals to a logic circuit (LK) which provides for exclusive control of the respective first or second half bridge. A lamp voltage sensing circuit (C4, R2) taps lamp operating voltage, which is compared with a command signal to control through a repetition frequency control generator (WG), the recurrence rate of the bursts from the power bursts generator (BG). The lamp starting circuit (4) can also be controlled from the sensed signal by comparison with a reference in a second comparator (K) and suitably applied to an ignition circuit by an ignition monitoring logic. A pair of electrolytic capacitors of essentially the same value is connected across the d-c supply and their midjunction to the lamp.
摘要:
To ensure ignition of a high-pressure discharge lamp, for example a metal vapor halogen high-pressure dicharge lamp which has an ignition circuit, and is operated by direct current from an inverter circuit controlled for pulse width modulation, current flow to the lamp is extended in time upon initial energization thereof so that an initial hot spot which forms on an electrode can remain hot to establish a stabilized arc. This extension of current flow can be obtained by an R/C circuit in parallel to the output or storage capacitor (C.sub.A) of the inverter circuit (FIG. 1) or by an NTC resistor (H) in series with the lamp, or by a resistor which is short-circuited by a relay contact as the lamp operates, or the like.
摘要:
A circuit arrangement for operating a discharge lamp, wherein the circuit arrangement comprises a commutation device, which has an input which is coupled to a DC source, and has an output which can be coupled to a discharge lamp. The commutation device is designed in such a way that it couples the DC source to the output, and the polarity at which the DC source is coupled to the output can be commutated by a control device. The control device has a sync input, and the polarity of the DC source is commutated in synchronism with sync pulses of a sync signal which can be applied at the sync input. The control device has a measuring input, which is coupled to a measuring device which is designed to provide a measured value which is a measure of the size of electrode peaks. The control device suppresses at least one commutation if the measured value overshoots or undershoots a predetermined threshold value.
摘要:
A circuit arrangement for operating a discharge lamp is provided. The circuit arrangement may include a commutating device, which is configured to exhibit an input which is coupled to a direct-current source and has an output which can be coupled to a discharge lamp; the commutating device being configured in such a manner that it couples the direct-current source to the output and the polarity with which the direct-current source is coupled to the output can be commutated by a control device; the control device including a measurement input which is coupled to a measuring device which is configured to deliver a measurement value which is a measure of the magnitude of a lamp voltage; wherein the control device is configured to control the commutating device in such a manner that the polarity at which a higher lamp voltage prevails is coupled longer to the output.
摘要:
A circuit arrangement for operating a discharge lamp is provided. The circuit arrangement may include a commutating device, which is configured to exhibit an input which is coupled to a direct-current source and has an output which can be coupled to a discharge lamp; the commutating device being configured in such a manner that it couples the direct-current source to the output and the polarity with which the direct-current source is coupled to the output can be commutated by a control device; the control device including a measurement input which is coupled to a measuring device which is configured to deliver a measurement value which is a measure of the magnitude of a lamp voltage; wherein the control device is configured to control the commutating device in such a manner that the polarity at which a higher lamp voltage prevails is coupled longer to the output.
摘要:
A circuit arrangement for operating a high-pressure discharge lamp with an operating circuit for the high-pressure discharge lamp with an input for receiving a switch-on/switch-off signal for the high-pressure discharge lamp and at least one output for providing an operating signal to the high-pressure discharge lamp, wherein the operating circuit is designed to reduce the power of the operating signal provided at the at least one output once a switch-off signal has been received at its input, wherein the operating circuit furthermore designed to provide the operating signal as an AC signal above a predeterminable power threshold value and as a quasi DC signal below the predeterminable power threshold value.