Projection bulb questions

[Kenetics]

I have heard a couple of things about projection bulbs and wonder if they are true:

1. The brightness of the bulb is fixed and does not change, regardless of the settings. Brightness of the display is controlled by other circuitry. True or false?

2. When bulbs are turned on, higher voltage is applied to "start" the bulb. That is why turning the tv on and off shortens the bulb's life. True or false?

[57U]

1. True, although some TVs have two settings for the bulbs, bright & less bright.

2. No, it's more to do with the thermal shock, same with an incandescent lightbulb in the house. They almost always "blow" when you first turn them on, however, a dimmer will extend the life of most incandescent bulbs by a lot, since they are not going "full blast" all the time.

[abeas]

Not sure about number 1, but I do know some TVs/projectors have a "normal" and "econo" mode. The econo mode is less bright and is supposed to lengthen bulb life.
Number 2 is false. I read about that somewhere, might have been on AVS Forum.

[oman321]

1. Interesting if it is the case, but what I have heard is that the bulb's brightness does diminish over time. Their probably is some circuitry that controls the brightness on your display that is not directly associated with the bulb. I've read that when you replace the bulb on RP sets that it as good as new as far as the image & brightness so to me that indicates that the bulb plays a big part over time.

2. These sets do keep track of the number of power ups and as indicated here several times are one the biggest stresses to the bulb as well as proper cool down for the bulb when powered off.

Edit: Sometimes I type slow what 57U and Abeas say makes plenty sense.