Category — Cool Components

I’ve used industrial barcode scanners a number of times, and they work well, especially the raster models.  The laser barcode scanners have a wide scan range and can handle a substantial amount of variation in label position.

My favorite  brand  is Microscan; I’ve also used other brands with good results.  The Microscan QX-870 is a typical  barcode scanner: it has 10 scan lines, can do 300 to 1400 scan/sec, has  a read range of 1″ to 30″, can read all the normal 1D barcodes (UPC, Codabar, Code 39, Code 128, etc)  as well as the PDF417 and Micro PDF417 2D barcodes.

However, most 2D barcodes (such as the popular Datamatrix) need an area sensor.  In other words, you can’t use a laser scanner, you have to use a camera.  Now finding a lens that has a 29″ depth of field (from 1″ to 30″) is challenging.  Of course, the barcode reader could use autofocus, but with a normal lens, that adds a lot of complexity, cost, and still isn’t perfect.  One Microscan 2D barcode reader had a halfway solution: the reader could cycle through a preset set of focus positions until it found a good read.  I wasn’t impressed (although to be fair, I never tried that model).

To make matters worse, Datamatrix codes are often used in direct marked applications; for example, using a laser or ball-peen to create a barcode directly on a metal aircraft part.  Creating lighting that is affordable, compact, and can work on anything from a shipping box to a reflective metal part is hard.

I’ve thought for a long time that liquid lenses (now available from optical suppliers such as Linos) could solve the depth of field problem by allowing affordable and rapid autofocus.  Well, they’re here (and both claim to be “the first”): Cognex has the Dataman 200 series, and Microscan has the QX Hawk with liquid lens and modular zoom.

I think this is a big deal; for example, the QX Hawk claims a read range of 1″ to infinity.  Unfortunately I don’t have any personal experience with either reader, but if I need to read 2D barcodes in the future, I will definitely check both out.

IDEC LW7L Push Buttons

Industrial style does matter.   That’s one reason I like IDEC’s LW7L flush mount pushbuttons.  Recently I was looking at some of our old equipment with Telemecanique pushbuttons that stick out over 5/8″ — those buttons are functional, but look dated.

The LW family of buttons is extensive (well over 10,000 combinations are available), but the models I like are the  LW7L-M1C64MG and similar.  What is good about them?

• They only need a light touch to operate (lighter than some other IDEC push buttons such as the HW2L series)
• High quality
• Long life LED lights available in amber, green, red, blue, white, and yellow.
• Powered directly by 24V (no resistors to worry about — I’ve destroyed LED lights from other companies).  6V, 12V, 120V, and 240V models are available, but I always use 24VDC.
• They are easy to install.
• The price is reasonable (around $30).  The Telemecanique buttons were much more expensive.   They aren’t the cheapest (e.g. the HW2L buttons are about $20), but I think the difference is well worth it because of the next point.
• They look great, with the square shape and flush mounting.  The traditional round, stick out 22mm push button makes equipment look like a retro-encabulator from the 1950’s.  I consider the extra cost over the HW2L buttons a marketing expense.

I also really like IDEC’s XW series of E-STOP switches — especially the models with a LED light.

I’ve discovered a lot of neat automation components over my decade plus doing system integration.  Unfortunately, I haven’t been able to use most of these products, but I’m starting a new series to highlight the most interesting ones.

Today’s focus is piezoelectric motors.

A piezoelectric material generates an electrical potential when stress is applied.  The reverse piezoelectric effect is when applying an electrical potential creates a stress in the material, changing its size slightly (typically by 0.1% or less).  This change in shape can be used in several different ways to create motion.

I first heard about piezoelectric motors back in the 1980’s when Canon introduced the traveling wave ultrasonic motors with their EOS autofocus camera system.

The first industrial piezo motors I heard about where piezo actuators, which just use the change of size in the piezo material to create movement.  This motor type is highly accurate (<1.0 nm), but the maximum move size is very small (typically <100 micron, although I’ve seen up to 500 microns).   For longer moves, you have to combine a traditional stage with the piezo actuator.  A variety of companies make this motor type; the ones I think of first are PI (Karlsruhe, Germany) and Mad City Labs (Madison, WI, USA).

Then I heard about the Nanomotion (Yokneam, Israel).  Nanomotion motors work by driving a piezo leg against a ceramic plate in an ellipse at high frequency.  Their industrial motor capabilities include:

• The same motor can be used for linear or rotary motion (with circular drive strip).
• When power is off, the motor holds the current position.
• Travel up to 2000 mm, speeds of over 200mm/sec
• Force up to 3.2 kg-f
• Motor can be operated in DC (actuator) mode to provide nanometer level precision.
• Good for some specialized applications, since the motors are non-magnetic, and vacuum-compatible versions are available.

You must use a Nanomotion amplifier; analog input is standard,  but  a CANOpen interface is available (it’s more expensive, since it uses the same analog amplifiers internally).  The amplifiers generate the high voltages (around 300V IIRC) required to drive the motors.

Nanomotion also sells high precision linear and rotary stages.  The rotary stages start around US$5000; just a motor and drive combo is around $1000 (but as always, check with Nanomotion for exact pricing).  Allmotion is now selling drives (controller and amp) for the Nanomotion HR series; pricing starts at $395.

A few years ago Nanomotion was acquired by Johnson Electric, a large Hong Kong-based manufacturer of motors and such, since Johnson Electric wanted to use their technology for cell phone camera modules.  Now Nanomotion produces small motors, zoom lenses modules, zoom camera modules, and custom driver ASICs, although you might need to be a high volume OEM to buy some of those products.

Next I heard about Piezo Motor AB (Uppsala, Sweden) which makes the Piezo LEGS and PiezoWave motors, which are also sold by Faulhaber (MicroMo in the US).  This Faulhaber link gives a nice summary of the standard PiezoWave linear motor and Piezo Legs linear and rotary motors.

At Photonics West a few years ago, I discovered DTI Piezotech (Sarasota, FL, USA) and New Scale Technology’s (Victor, NY, USA) Squiggle motor.

The Squiggle motor works by creating ultrasonic vibrations that cause a nut to travel in or out.  They are oriented towards small, large volume applications.  New Scale’s standard motors range from 6mm travel and 0.3N force to 50mm travel and 5N force.

New Scale has an extensive product line, including standard motors, custom motors, driver ASICs, driver boards, development kits, USB control and driver,  standard stages, and magnetic position sensors.

New Scale has a web store that sells a variety of their products — I like it!

DTI Piezotech is part of Discovery Technology International which makes bioinstrumentation.  Their initial product was a rotary motor (the first I heard about); IIRC, initially they only sold the motor as part of a complete, high precision stage.  Now they have really broadened their product line, with a variety of sizes  of both linear and rotary motors.

Standard rotary motors range from 2 mM-m to 6 N-m force; linear motors go up to 50N-m and 1,000 mm/sec.  Like Nanomotion, DTI linear motors can also operate in actuator mode for ultra precise positioning.   I couldn’t find much information on their drivers, but they do have development kits, with controller boards, available.

One of my readers (thanks, Bob!) mentions yet another company, Elliptec (Dortmund, Germany), with yet another approach (piezo controlled lever moving a gear seems like a decent description).

I took a quick look at PI’s web site; they now sell a broad range of piezo motors, including actuators, rotary motors, and linear motors.

Finally, while doing research for this post, I came across PCB Motor (Hillerod, Denmark) which makes parts that can assembled on PCBs to create motors on printed circuit board.  They have on-line ordering of their development kits.

BTW, the wikipedia piezoelectric motor page is pretty weak – it doesn’t cover most of the companies or approaches I cover.

I learned a lot writing this blog post – I hope you enjoy it!