Projector Lamp Life Explained
Technology brief
Overview
Christie categorizes a lamp as having reached the end of
its life if the lamp:
The expected operating time for any projector lamp is
usually referred to as ‘lamp life’. The length of time that
a lamp will operate depends on the type of lamp (Figure
1) and the power level (eg. 200W, 350W, etc.). Generally,
lower power lamps tend to outlast higher power lamps.
There are two elements that need to be considered when
discussing lamp life. The first is the expected length of
time that the lamp will operate. The second, less obvious,
is known as the brightness decay curve. This is the
lamp’s brightness decline over the operating period.
•
Begins to flicker
•
Fails to strike reliably
•
Fails to remain lit
•
Physically breaks
A common lamp failure rate curve (Figure 2), shows the
expected rate at which lamps will reach end-of-life as the
lamp ages.
For the example lamp in Figure 2, 2000 hours would be
the point at which half of the lamps produced from a large
production sample will have reached the point of failure.
Therefore, the typical lamp life for this lamp is 2000 hours.
Furthermore, using the lamp failure curve, one would
see that a small percentage of lamps (approximately
5% of total lamps produced) will not reach 200 hours.
Many manufacturers, including Christie, offer a pro-rated
lamp warranty to compensate customers for these rare
instances of early failure. Seventy percent of lamps will
achieve between 2200 and 2700 hours and the remaining
30% will operate between 2200 and 2900 hours.
Figure 1. Lamp types
Lamp operating life
Factors such as statistical variances in manufacturing
batches and material impurities can affect the life of each
individual lamp. When a company states the ‘typical’
lamp life in their documentation, it does not mean that
every lamp will last that stated number of hours.
In the projection industry, “typical lamp life” is
defined as the time at which 50% of the total number
of lamps produced, reach the end-of-life.
christiedigital.com
Failure rate (% of all lamps produced)
100
90
80
70
Typical life low power
(ECO mode)
60
Typical life full power
50
40
30
20
10
0
500
1500
2000
Time (hrs)
2500
3000
Figure 2. Typical lamp failure rate
By and large, the shape of the curves in Figure 2 reflects the
majority of the lamps currently in production. If a lamp is
specified at 1000 hours or conversely 3000 hours, the curves
still hold true and can be used to determine the failure rate.
Projector Lamp Life Explained
Technology brief
Lamp brightness decay
Eco mode
All projector lamps have a characteristic brightness decay curve
(Figure 3) that describes the expected output in brightness over
the lamp’s operating life. Different types of lamps have different
curves. To estimate the expected brightness of a projection
system at any point in the lamps operating life, the brightness
decay curve for that system’s lamp should be used. Figure 3
represents a brightness decay curve for a typical projector lamp.
Light output (% of initial brightness)
100
Power off
90
80
70
Low power
60
50
(eco mode)
Full power
40
30
Lamps typically don’t last as long in 24/7 applications as they
do in applications when they can be occasionally turned off;
much like the lights in a home or office. To conserve power
and extend lamp life, users should power off a projector that
is not in use. This should be done manually or automatically
depending on the projector and its application.
Filters
20
10
0
Today, many projectors are designed to operate the lamps in
either full-power or a reduced-power mode (usually referred
to as ‘eco mode’). Depending on the model, lamp power,
and lamp type, a reduction in 20% of the lamp’s light output
and power draw may yield longer lamp life. Consult the
projector’s technical specifications for more information
about the eco mode rating for your model.
500
1000
Time (hrs)
1500
Figure 2. Typical lamp brightness decay curve
In this example, you can see that after 500 hours of lamp
usage, the system will have approximately 65% of its initial light
output if the system was operated using its maximum power
mode and about 75% if operated in a lower power eco mode.
Extending lamp life
Properly maintaining your projector will help maximize
brightness and lamp life. Three things that you can do to extend
lamp life are:
1) Use the ’eco mode’
2) Power off the projector when not in use
3) Regularly clean or replace the filters
Dirty filters in a projector can reduce lamp life as well as
negatively affect the performance of other optical/electrical
components inside the projector. To ensure the maximum
performance of the projector, filters must be clean and therefore
should be replaced each time a new lamp is installed.
Conclusion
When considering a projector’s lamp life, it is important to
understand that this value is an estimate of the time it will take
for the average lamp to reach its end of life. While there are
measures that can be taken to maximize this time, there is
no guarantee of expected time of use or of expected brightness
performance over that time.
It is important to clearly understand the difference between the
lamp brightness decay and lamp failure rate curves. These two
factors will help installers and end users gauge the expected
replacement cycles for lamps, as well as specify a projector’s
brightness based on the lifetime brightness decay curves. These
are key considerations when selecting a projector rather than
relying on lumen values alone.
Independent sales
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Christie Digital Systems Canada, Inc.
Canada – Kitchener
ph: 519 744 8005
For more information, please visit www.christiedigital.com
Copyright 2010 Christie Digital Systems USA, Inc. All rights reserved. All brand names and product names are trademarks, registered trademarks
or tradenames of their respective holders. Canadian manufacturing facility is ISO 9001 and 14001 certified. Performance specifications are typical.
Due to constant research, specifications are subject to change without notice. Lamp Life Technology Brief. Aug 2010