A discharge lamp driving device includes a discharge lamp driving unit configured to supply a driving current to a discharge lamp, and a control unit configured to control the discharge lamp driving unit. The discharge lamp driving device is configured to provide a first hybrid period and a second hybrid period each alternately including a first AC period in which an AC current is supplied and a first DC period in which a DC current with a first polarity is supplied. The control unit, in the first hybrid period, is configured to change a ratio of length of the first DC period to length of the first AC period to be increased, and in the second hybrid period, is configured to change a ratio of the length of the first AC period to the length of the first DC period to be increased.

An electronic circuit for protecting a load against over-voltage is disclosed. The electronic circuit comprises an input port for receiving a voltage and an output port for feeding the voltage to the load. The electronic circuit further comprises a switching unit arranged to switch on and off the voltage from the input port. Moreover, the electronic circuit comprises a capacitive component arranged to receive the voltage when the switching unit is switched on and is otherwise arranged to feed voltage to the output port. Furthermore, the electronic circuit comprises a comparing unit configured to control the switching unit to be switched off when a value at the output port exceeds a first threshold; and to control the switching unit to be switched on when the value is below a second threshold.

A device for providing power to a light arrangement (1) having a current conducting state and a current blocking state. The device comprises a storage circuit (2) with a capacitor (21) coupled to the light arrangement (1) and a resistor (22) located in parallel to the capacitor, a first determination circuit (3) for determining the state of the lighting arrangement, a second determination circuit (4) for, in the current blocking state, determining points of two discharging curves of the storage circuit, a derivation circuit (5) for deriving a condition of the storage circuit, such as life-end, from the discharging curves, a switch circuit (6) comprising an element (61), wherein the switch circuit is configured to switch the element (61) in parallel to the capacitor (21), whereby a first discharging curve is determined with the element being disconnected from the capacitor and a second discharging curve is determined with the element being connected to the capacitor, the capacitor discharging via both the resistor (22) and the element (61). The element (61) may comprise a resistor, a capacitor or an inductor.

There is provide a discharge lamp lighting apparatus that comprises a discharge lamp and a power supply device configured to drive a regular lighting mode and the low electric power lighting mode in a switchable manner. The power supply device configured to control a power supply to the discharge lamp such that, in the low electric power lighting mode, after a secondary protrusion forming process in which an alternating current having a frequency equal to or greater than the basic frequency in the regular lighting mode is supplied, the low electric power lighting mode transitioning to a secondary protrusion maintaining process in which a high frequency alternating current having a frequency higher than the basic frequency in the regular lighting mode, and a low frequency alternating current having a frequency lower than the frequency of the high frequency alternating current is alternately supplied.

A projector which configured to project a horizontally long image and a vertically long image, includes a cooling unit configured to cool a discharge lamp according to an installation attitude of the projector, a detection unit configured to detect the installation attitude, and a controller configured to control a discharge lamp driving unit and the cooling unit, in which the installation attitude includes a first attitude for projecting the horizontally long image and a second attitude for projecting the vertically long image, and in which the controller is configured to put out the discharge lamp in a case where the installation attitude detected by the detection unit is a third attitude which is different from both of the first attitude and the second attitude.

A projector which configured to project a horizontally long image and a vertically long image, includes a cooling unit configured to cool a discharge lamp according to an installation attitude of the projector, a detection unit configured to detect the installation attitude, and a controller configured to control a discharge lamp driving unit and the cooling unit, in which the installation attitude includes a first attitude for projecting the horizontally long image and a second attitude for projecting the vertically long image, and in which the controller is configured to put out the discharge lamp in a case where the installation attitude detected by the detection unit is a third attitude which is different from both of the first attitude and the second attitude.

A device may include a power source, two or more lamps for providing light, and a controller. The controller may be configured to periodically select a first combination of one or more of the lamps, provide power from the power source to the first combination of the lamps, select a second combination of one or more of the lamps, and switch the power from the first combination of the lamps to the second combination of the one or more of the lamps after a period of time has elapsed.

The invention provides a High Intensity Discharge (HID) lamp acoustic resonance suppression method. Whether acoustic resonance is produced or not is judged, and a frequency-modulated current frequency provided by a ballast when the acoustic resonance is produced to fulfill the aim of suppressing the acoustic resonance. The ballast includes an acoustic resonance elimination module. The invention has the beneficial effects that due to the additional arrangement of the acoustic resonance elimination module, acoustic resonance is maximally suppressed, and the optimal stability of a discharge arc is ensured. These characteristics enable the product to stably run for each type of lamp tube and different power.

A discharge lamp driving device includes a discharge lamp driving section configured to supply a driving current to a discharge lamp, the driving current being an alternating current for driving the discharge lamp, and a control section configured to control the discharge lamp driving section. The control section controls the discharge lamp driving section such that the driving current having a driving frequency different from a natural frequency of the discharge lamp and a frequency of 1/2n (n is a natural number) times the natural frequency is supplied to the discharge lamp.

The invention describes an ignitor arrangement (1) for a high-intensity discharge lamp (2), which ignitor arrangement (1) comprises a first pair of input terminals (101, 102) for applying an ignition voltage to the ignitor arrangement (1); a second pair of input terminals (101, 103) for applying an input drive voltage to the ignitor arrangement (1); and a discharge resistor (10) arranged in the interior (100) of the ignitor arrangement (1) and connected across the first input terminal pair (101, 102), which discharge resistor (10) is realised as a temperature-dependent resistor (10). The invention also describes a lamp driver (3) realised to drive a high-intensity discharge lamp (2); a lighting arrangement (4); and a method of driving a high-intensity discharge lamp (2).