Components Division

"72" Series Indicator Flip Dots 

The "72" series indicator flipdots are bi-stable electromechanical indicators that are commonly used to form alphanumeric characters in a matrix arrangement (5 by 7 is typical).  They can also be used as single indicators or in groups to indicate counts.  They are commonly used in public display systems.

Construction

The flip dot consists of a disk that is brightly colored on one side and black on the other side, attached to a rotating shaft with a permanent magnet on the end of the shaft.  Just under the magnet is a coil with a steel core which can be magnetized in either direction to force the permanent magnet to rotate in either direction.  The coil is typically energized for only two milliseconds, and the steel core retains the magnetism to rotate the permanent magnet and hold the shaft in the rotated position.  Power is briefly required only when commanding the dot to the other position--NO POWER IS CONSUMED WHEN THE DOT IS DISPLAYING.

Brightness and Contrast

Ambient light is normally sufficient to produce a high contrast display.  This product excels in bright sunlight where other technologies have difficulty in competing with the brightness of the sun.  It also maintains suitable brightness levels automatically (since it is driven by ambient light).  Compared to other low power displays (like reflective LCD's) this technology excels in contrast, with contrast ratios many times that of LCD's.  Translated, these are ultra low power indicators that can be seen for long distances.

Simplicity in Operation

The drive circuitry is simple.  The dots have a center taped winding configuration with three terminals.  The simplest operation is by connecting the center tap to a positive source (the nominal voltage for the coil is 12 volts DC), and to "flip" the dot, either end of the coil is momentarily connected to ground.  Two milliseconds are all that's required to magnetize the steel core to flip the dot.  

When using groups or matrixes of dots, the coils are commonly connected in a multiplexing arrangement that greatly reduces the number of connections to the group and lowers the cost of the drive circuitry.  In a 5 by 7 arrangement, only 19 wires are required to control all 70 coils.  To flip, each coil requires 580 ma for 2 ms, and in a 5 x 7 matrix arrangement, seven coils (one column) are strobed together.  Typically the row drivers source 580 ma each, and the column drivers sink 4 amps, again with 2 ms pulses.  Circuitry to sink and source these currents is simple and inexpensive.  

Very Very Low Power

Because the display state is held magnetically from the magnetism in the steel core, when the message or indication is not being changed, these indicators draw ZERO power.  This is the only display technology that has this characteristic.  

If the information is not changed rapidly, for instance once every five seconds, the average power consumption of these indicators is very, very low.  In the example of changing once every five seconds, the average current consumption is 163 micro amps per dot! (.002 watts)

When used in small groups, the coils can be driven one-at-a-time, reducing the peak current to 580 ma (again, for 2 ms per dot), which is well within the capability of small batteries.

Here To Stay

The Staver Company invented this product and sold it for many years under the Signalex brand name.  When the owners of Staver retired, they sold their company to a Colorado based company who produced the product for several years.  In spring 2002, ScoreTronics (a scoreboard company who uses the "72" series dots in their products) purchased the inventory and tooling to produce the product.  Within weeks, ScoreTronics was producing the product with superior quality and lower prices, and selling the product world wide.  

In addition to supplying their growing scoreboard business, ScoreTronics sees this as a viable product--one that will provide many years of sales.  ScoreTronics' plans for the product is to produce and fully support it for a very long time to come.

ScoreTronics Inc., Components Division
7320 S Madison St, Unit 1100, Willowbrook, IL  60527
Toll free (888) 456-1970,  (630) 323-4600,  fax (630) 729-3206

Email: sales@scoretronics.com