The respective proportionality constants of magnetic force by magnetic field producing portion for biasing the plug in the direction of insertion and resilient force by a spring mechanism for biasing the plug in the direction of extraction are adjusted in such a manner that the resilient force is greater than the magnetic force until the plug pin reaches an intermediate insertion position at which the plug pin comes into proximity to or separates from the socket contact, whereas the magnetic force is greater than the resilient force at a position at which the plug pin is inserted into a complete insertion position for a hot-line connection to the socket contact. The plug pin in the vicinity of the intermediate insertion position, at which there is a possibility of occurrence of an arc discharge, is ejected by the resilient force.

In a discharge lamp driving device, a mixed period is provided, in which a first period in which an alternating current is supplied and a second period in which a direct current is supplied are alternately repeated and a third period alternately including a first direct current period and a second direct current period in which a direct current having a polarity opposite to a polarity of the direct current in the first direct current period is supplied. Length of the second direct current period is smaller than 0.5 ms. A total of lengths of the first direct current periods in the third period is larger than length of the second period. The third period is not provided at least when the inter-electrode voltage is smaller than a first predetermined value or when a cumulative lighting time of the discharge lamp is smaller than a second predetermined value.

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.

A discharge lamp driver includes a discharge lamp driving unit configured to supply drive current to a discharge lamp and a control unit configured to control the discharge lamp driving unit. The drive current has a modulation drive period in which a first period in which AC current having a frequency higher than 1 kHz is supplied and a second period in which DC current is supplied are alternately repeated. In the modulation drive period, the control unit periodically changes length of a first DC period included in the second periods and in which DC current of a first polarity is supplied, and length of a second DC period included in the second periods and in which DC current of a second polarity is supplied, and increases one of the length of the first DC period and the length of the second DC period while decrease the other one.

Electrodeless high intensity discharge (HID) lamps have the promise of higher reliability and higher efficiency than traditional electroded high intensity discharge lamps. However, most electrodeless HIDs operate in the frequency range of around 400 MHz or higher resulting in expensive, inefficient RF drivers that reduce the overall efficacy of the lamp. Operating the lamp at lower frequencies results in substantial increase in the physical dimensions of the resonators used in traditional electrodeless HIDs. In this invention a novel wave-launcher technology is used allow the lamp housing's operating frequency to be independent of the physical dimensions of the lamp housing. This provides an avenue to increase the conversion efficiency of the RF driver and the efficacy of the lamp system.

A discharge lamp driving device according to one aspect of the invention includes a discharge lamp driving section configured to supply a driving current to a discharge lamp including electrodes and a control section configured to control the discharge lamp driving section. The control section controls the discharge lamp driving section such that a mixed period is provided in which a first period in which an alternating current having a first frequency is supplied to the discharge lamp and a second period in which a direct current is supplied to the discharge lamp are alternately repeated. The first frequency includes a plurality of frequencies different from one another. The control section temporally changes the length of the first period.

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.

The present disclosure relates to a light attenuation controlling apparatus for a CDM lamp, comprising: a full-bridge inverter as a power source to supply an output to the CDM lamp; a driving circuit for driving the full-bridge inverter; a single-chip microcomputer connected to the driving circuit; a tube voltage sensing module, one end of which is connected to the full-bridge inverter so as to sense a tube voltage currently outputted by the full-bridge inverter to the CDM lamp, and through the other end of which the tube voltage of the CDM lamp is outputted to the single-chip microcomputer. The present disclosure provides a novel light attenuation controlling apparatus for a CDM lamp, which can effectively control light attenuation of the CDM lamp by constantly regulating the output of the full-bridge inverter, thereby enhancing duration of the CDM lamp.

A discharge lamp lighting device according to an aspect of the invention includes a resonance circuit unit connected to a discharge lamp, a power converting unit configured to convert direct-current power into alternating-current power and supply the alternating-current power to the discharge lamp via the resonance circuit unit, and a control unit configured to supply the alternating-current power having a first frequency for causing resonance of the resonance circuit unit and a second frequency different from the first frequency, to the discharge lamp in a lighting start period from a start of lighting of the discharge lamp to a steady lighting state of the discharge. The second frequency is equal to or higher than 100 kHz.

Various embodiments relates to a DLP (digital light processing) projector for projecting at least one image on a projection surface. A discharge lamp is driven by a current waveform having at least one first region, to which a first frequency is assigned, and a second region, to which a second frequency is assigned, wherein the first region is established by a first commutation and a following second commutation, wherein the second region is established by the region between the second commutation and a following first commutation, wherein further commutations can occur within the second region, wherein a modulation factor is defined by the ratio of second frequency to first frequency, wherein the modulation factor is at least 3. A method for projecting at least one image is also disclosed.