Discharge lamp lighting device, method of driving discharge lamp, and projector

[0158] In the above-mentioned embodiment, the case where the duty ratio of the AC drive current I is randomly changed has been described, however, control for randomly changing the frequency of the AC drive current I may be applied. That is, it is also possible that the storage unit 44 stores the frequency of the AC drive current I as a driving parameter for specifying the AC drive current I, and the control unit 40 selects the AC drive current I from the values ​​in the third range with a given probability based on the given time condition. The value of the frequency of the driving current I is used to control the discharge lamp driving unit based on the selected value of the frequency of the AC driving current.

[0159] The control unit 40 may set the third range based on the drive voltage Vd of the discharge lamp detected by the voltage detection unit of the operation detection unit 60 .

[0160] Next, use Figure 7 An example of the procedure for changing the frequency of th

[0173] Although in the above-mentioned embodiment, the case where the waveform of the AC drive current I is a rectangular wave has been described, it is also possible to control the AC drive current I by changing the duty ratio D of the AC drive current I randomly. The control that the waveform of the current I changes randomly. That is, the storage unit 44 may also store the waveform of the AC drive current I as a driving parameter for specifying the AC drive current I, and the control unit 40 selects the AC drive current I from a plurality of selectable waveform patterns with a given probability based on a given time condition. The waveform of the driving current I controls the discharge lamp driving unit based on the selected waveform of the AC driving current I.

[0174] The control unit 40 may set a plurality of selectable waveform patterns based on the drive voltage Vd of the discharge lamp detected by the voltage detection unit of the operation detection unit 60 .

[0175

[0182] In the above-mentioned embodiment, an example in which the duty ratio is selected and driven every cycle has been described as the given time condition, but the control unit 40 may be based on the voltage detection unit of the operation detection unit 60 The detected driving voltage Vd of the discharge lamp is used to set the given time condition.

[0183] Below, use Figure 7 An example of the procedure for changing the given time conditions will be described.

[0184] Figure 7 In the shown process, steps S100-S102 are the same as the above-mentioned embodiment.

[0185] Figure 7 In step S104, the driving parameter is selected based on the random number Rn and the driving voltage Vd by using the driving parameter selection mechanism 40-4. In the present embodiment, an example of a time (corresponding to a given time) before changing a driving parameter which is one of the driving parameters will be described.

[0186] Figure 6 (A) and Figure 6 In (B), the tenth