An image display apparatus including a light source; a light source control unit configured to control electric power to be supplied to the light source; a light source cooling unit configured to cool the light source; a cooling control unit configured to control the light source cooling unit; an image display device; an illumination optical system configured to introduce light from the light source to the image display device, and a projecting optical system configured to project light modulated by the image display device. When the light source control unit receives a turn-off command, the light source control unit first lowers electric power to be supplied to the light source to a predetermined electric power lower than normal electric power to be supplied when the lamp is on, and then blocks the supply of the electric power to the light source, thereby turning the light source off.

According to the present disclosure, a method for operating a discharge lamp of a projection arrangement is provided. The method includes storing the first commutation scheme in the ballast, such that the first commutation scheme fulfils a specification with respect to a first criterion, wherein the first criterion represents an electrode burnback; storing of the second commutation scheme in the ballast, such that the second commutation scheme fulfils a specification with respect to a second criterion; and operation of the discharge lamp with the alternation of the first and the second commutation schemes; characterized in that, a periodic brightness fluctuation in the discharge lamp is employed as the second criterion.

The discharge lamp lighting device for supplying alternating current to a discharge lamp includes: a power supply control part having a segment signal generation part, a peak value control part, and a frequency control part; and a power supply part. The peak value control part sets a specific segment period, which indicates a value where a value of integral corresponding to a product of the length of the segment period and a peak value set in a segment period is most deviated from an average value of the values of integral within the specific period, to a period other than a final segment period positioned at the final end of the specific period, among a plurality of segment periods belonging to the specific period.

A discharge lamp driving device includes a discharge lamp driving section configured to supply a driving current to a discharge lamp including a first electrode and a second electrode and a control section configured to control the discharge lamp driving section. The control section is configured to repeat a unit period. The unit period includes a direct current period including a first direct current period in which a direct current having a first polarity is supplied to the discharge lamp and a second direct current period in which a direct current having a second polarity is supplied to the discharge lamp, and an alternating current period provided between the first direct current period and the second direct current period, an alternating current being supplied to the discharge lamp in the alternating current period. The control section is configured to temporally change length of the direct current period.

A discharge lamp driver includes a discharge lamp drive unit that supplies a drive current to the discharge lamp, and a control unit that controls the discharge lamp drive unit according to a drive current waveform, wherein the drive current waveform has a mixed frequency drive period including a unit drive period containing a first drive period in which a first drive current is supplied to the discharge lamp and a second drive period provided immediately after the first drive period, in which a second drive current is supplied to the discharge lamp, the first drive current is a half-period alternating current having a frequency higher than 10 Hz and not higher than 300 Hz, the second drive current is an alternating current having a frequency higher than 1000 Hz, and a length of the second drive period is equal to or longer than a length of the first drive period.

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 discharge lamp driving device includes a discharge lamp driving section configured to supply a driving current to a discharge lamp, a control section configured to control the discharge lamp driving section, and a voltage detecting section configured to detect an inter-electrode voltage. The control section supplies a driving current including a first alternating current when the inter-electrode voltage is equal to or higher than a first voltage, supplies a driving current including a second alternating current having a frequency which is lower than a frequency of the first alternating current when the inter-electrode voltage is lower than the first voltage and equal to or higher than a second voltage lower than the first voltage, and supplies a driving current including a third alternating current having a frequency which is higher than the frequency of the first alternating current when the inter-electrode voltage is lower than the second voltage.

A lighting device includes a plurality of light source devices and a holding member (first lamp unit and second lamp unit) holding the plurality of light source devices. The light source device has a light source and a storing body for storing the light source. The storing body has a plurality of openings introducing cooling gas and the holding member (first lamp unit and second lamp unit) includes a diverging device guiding the cooling gas to at least one opening among the plurality of openings.

An image projection apparatus includes: a light source; an image display element including multiple micromirrors arranged in two dimensions, the multiple micromirrors forming an image display plane, each micromirror having a reflecting surface; and a projection optical system. Conditional expressions (1) and (2) below are satisfied:

θ1≥14 (deg)  (1)

1.2<BF/L<2.2  (2) where θ1 is a maximum tilt angle of the reflecting surface of each micromirror with respect to the image display plane, L is a diagonal length of the image display plane, and BF is a distance between a vertex of a lens within the projection optical system and closest to the image display plane and the image display plane along an optical axis of the projection optical system.

Dual or multi-modulation display system are disclosed that comprise projector systems with at least one modulator that may employ non-mechanical beam steering modulation. Many embodiments disclosed herein employ a non-mechanical beam steering and/or polarizer to provide for a highlights modulator.