User Manual

Page 49
Figure 59. ACH-01-XX internal view
Figure 60. ACH-04-08-05 internal view
Vending Sensors
Shielded dynamic strain gages of piezo film are affixed to the underside of a vending product delivery
tray to verify that product was properly vended. The absence of the impact induced vibration triggers
an "Out of Order" warning. In a second application, slot machine coin counting is provided by a piezo
film element. The sensors confirm delivery of coins won, discouraging gamblers from falsely claiming
equipment defects. A ticket dispensing machine counts tickets delivered with a piezo beam design.
Coin sensors also trigger or wake-up vending machines and coin changer electronics to verify coin
authenticity.
ACCELEROMETERS
A logical outgrowth of the many vibration sensor
applications of MSI’s piezoelectric technology are
accelerometers. These accelerometer designs are
based on more traditional piezoelectric ceramic, as
well as piezoelectric polymer materials. The choice
of base materials allows the product to be tailored
for specific applications. Table 6 lists the key
specifications for the MSI Accelerometer product
family.
Like more conventional sensors, these accelerometers are configured as either compression-design type
or beam-design type. Compression-design accelerometers typically have higher resonant frequencies
providing wide useful frequency ranges. An internal view of MSI’s ACH-01-XX compression-design
accelerometer is shown in Figure 59.
Beam-design accelerometers tend to have lower resonant
frequencies and useful frequency ranges. Beam-design
accelerometers also have another very interesting feature:
They can be oriented to sense acceleration in multiple-axes
with one monolithic sensing element using MSI’s patented
“Origami” beam technology (“Origami” is the Japanese
word for the art of paper folding). An internal view of the
ACH-04-08-05 three axis beam-design accelerometer, with
its origami sensing element, is shown in Figure 60.
To reduce system costs as well as simplify use, all of MSI’s
accelerometers include buffers. JFET biasing and signal
processing is implemented external to the device.
The ACH-01 family of products is typically used in
applications which require broad frequency capability, high sensitivity, low noise, and low cost. Such
applications include: speaker feedback and control systems, automotive anti-theft systems, acoustic
pick-ups, machine-health and pump and centrifuge monitoring systems, and medical body motion
monitoring.
The ACH-04-08 product family is used in a very broad range of applications such as speaker feedback
and control systems, appliance fault monitoring, virtual reality systems, automotive systems, medical
body motion monitoring, shipment damage and material-handling monitoring systems, vibration
switches and earthquake shut-off switches. OEM applications that require acceleration or vibration
measurements in more than one axis are perfect for the ACH-04-08-05.
MSI is constantly developing and upgrading its accelerometer product line. Please contact MSI for
further details on these products or on customizing one of our other products.