FireFly –VS- ZEEION
We acquired three,
brand new, ZEEION
Anti Static Blowers (By Visible Dust) with the intent of comparing their
performance to the performance of the FireFly
Digital Sensor Cleaner (By NRD), which we already had. This proved to be an
interesting exercise, because identifying, selecting, and then implementing an
objective test method is critical to the validity of the conclusions one could
reach upon evaluating the test results.
Our first thought was
the obvious test of comparing how well either product could remove the dust
from a camera sensor. For this to be reasonably objective, we would need to
know a lot about the composition and particle size distribution of our dust. We
would also need to control the number of dust particles placed onto the camera
sensor before each trial. And, to minimize the impact of environmental
conditions on our results, we would want to perform these tests in a class 100,
or better, clean room. This was starting to look like a lot of time and effort.
Then we asked
ourselves, what single characteristic, shared by these two different
anti-static blowers, would be the most important characteristic necessary for
removing dust from a camera sensor. We believe that without the air, compressed
by the hand operated bulb and then ejected from the nozzle, it would be very
difficult, if not impossible, to remove dust from a camera sensor. It was time
to change the question.
O.K. – What unique,
single characteristic, shared by these two different anti-static blowers, would
be the most important characteristic necessary for removing dust from a camera
sensor? Air Ionization is what both manufacturers claim makes their products
able to quickly and safely remove dust from a camera sensor. They claim that by
ionizing the air stream delivered to the nozzle, static charges that are
holding dust onto the sensor can be neutralized, allowing the air stream to
sweep the dust away from the sensor. Now we have a performance characteristic
that can be measured with the appropriate instrumentation, and then objectively
evaluated.
A review of the
literature from each manufacturer shows a very important difference in the
ionization characteristics. The ZEEION creates only NEGATIVE ions, whereas the
FireFly creates both POSITIVE and NEGATIVE ions. We will need to consider this
when we choose a test method. However, as a sidebar and from a practical
standpoint, the FireFly can neutralize both POSITIVE and NEGATIVE static
charges, but the ZEEION can only neutralize POSITIVE static charges. This means
that the ZEEION may not be effective in circumstances where dust is being held
by a NEGATIVE static charge.
As we considered various instruments and methods to evaluate the ionization created and delivered by the ZEEION and the FireFly, we reviewed Standards and Advisories published by the Electrostatic Discharge Association. Two documents in particular, ESD ADV 3.2-1995 “Selection and Acceptance of Air Ionizers”, and ESD STM 3.1-2000 “Ionization”. From this we concluded that the best method we could employ to evaluate and compare the performance of the ZEEION and the FireFly would be to measure the discharge time of a charged plate. We elected to utilize a Trek model 158 Charged-Plate Monitor with a Trek model 156P one-inch by one-inch square plate.
Because the ZEEION can
only generate negative ions, and therefore it can’t neutralize the charge on a
negatively charged plate, we decided to measure the time required to discharge
the plate from a positive 1000 volts down to a positive 100 volts. Opting to
measure the decay time between 1000 volts and 100 volts is a common practice
and is discussed in the standards referenced above.
To minimize the influence of unknown and undesirable electrical charges in the
test environment, our charge plate and monitor would be placed onto a grounded,
static dissipative surface, and a grounded wrist strap would be worn on the
hand that was used to operate each blower bulb. We would hold the outlet
nozzle, of the device under test, at a distance of approximately one-inch from
the charged-plate. We would initiate the preprogrammed test sequence and then
squeeze the blower bulbs as hard and fast as possible during the 30-second
test, or until the plate voltage dropped below 100 volts.
After setting up the equipment in the test area, we
configured the Trek Charged-Plate Monitor to perform decay time measurements
from a positive 1000 volts to 100 volts and programmed a time limit of 30
seconds on each test. Before running the experiment, we ran a couple of quick
tests of the FireFly, and observed that we could get consistent, reasonable
decay times. But, tests of the ZEEION showed NO voltage decay during the
30-second tests. It became obvious that this test method would not provide
useful data for the ZEEION.
By knowing the
capacitance of the plate and the voltage on the plate, we can calculate the
charge on the plate using the following equation:
Where: 
is the charge present
on the plate, with the unit of Coulomb
is
the capacitance of the plate, with the unit of Farad
is
the voltage present on the plate, with the unit of Volt
This gave us a method
to measure the negative charge delivered to the plate by the ZEEION in 30
seconds. We couldn’t use this method to measure the charge delivered to the
plate by the FireFly because the FireFly generates both positive and negative
ions, with a net of zero. However, we can still use the decay rate test to
indirectly measure the negative charge delivered to the plate by the FireFly.
By charging the plate to a positive 1000 volts, then measuring the time
required to discharge it to 100 volts, we can calculate the charge neutralized
(or delivered to the plate) using the following equation:
Where: 
is the charge present
on the plate at 1000 volts
is
the charge present on the plate at 100 volts
First we configured the
Trek Charged-Plate Monitor to measure the offset voltage, averaged over a
30-second period, and proceeded with the experiment.
We ran three trials on each of the three ZEEION Anti Static Blowers, for a
total of nine trials, and averaged the offset voltage readings. The average
offset voltage reading was –3.86 volts. Calculating the charge we have:
The negative sign in V
and Q above indicate the polarity of the voltage and charge on the plate. We
can now calculate the charge generation rate by dividing the charge by the time
period. Ignoring the negative sign we have:
Lets compare the charge generation rate of the ZEEION to
that of the FireFly by expressing it as the ratio of the larger rate to the
smaller rate:
This demonstrates that the FireFly generates approximately 2500 times as much neutralizing charge per second as the ZEEION. From this, one could conclude that the FireFly would be immensely more effective than the ZEEION across a broader range of conditions.
Summary: In the static control world, you use both polarities of ions (NEGATIVE & POSITIVE) to neutralize a static charge, using a single polarity can actually cause damage under the right conditions. The FireFly emitting both NEGATIVE and POSITIVE ions meets its claim to remove the static charge from the sensor, releasing the dust. The ZEEION on the other hand only emits a single polarity (very small amounts of NEGATIVE ions) and FAILS to remove the static charge holding the dust on a sensor.
If you would like to see a spec sheet on the test
equipment used in this test, please visit
http://
www.trekinc.com/products/158.asp
If you would like to see a visual demonstration, please
visit
http://www.dustfreephoto.com/Blower-Challenge.html
For more information on the Sensor Cleaning subject,
please visit our web site at
http://www.
CleaningDigitalCameras.com