Modular sealed portable digital electronic controller

Abstract

An electronic digital controller, such as a load cell indicator, is disclosed in which a number of components, such as a circuit board, display, and keypad are placed within an enclosure, and the enclosure is bonded closed, such as using an adhesive, to render the enclosure watertight. The keypad is a touch sensitive, capacitive keypad with no moving parts, and it is housed behind a rigid panel. An optoelectronic transceiver allows for data exchange with an electronic memory device housed in the adhesively sealed enclosure and allows for data exchange and for updating or modification of software code housed therein. Other components, such as another circuit board, a power supply, and block connectors, are placed in an adjacent enclosure, and the circuit boards in the two enclosures are electrically connected. The power supply is preferably a potted AC power supply but may also include a battery.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of co-pending U.S. patent application Ser. No. 11 / 198,110 filed on Aug. 5, 2005 and having the inventors Timothy R. Cox, et al., which claims benefit of U.S. patent application Ser. No. 10 / 345,566 filed Jan. 16, 2003, now U.S. Pat. No. 7,002,084 issued on Feb. 21, 2006, which claims benefit of U.S. Provisional Patent Application Ser. No. 60 / 350,297 filed Jan. 16, 2002. Each of the aforementioned related patent applications and patents is herein incorporated by reference.BACKGROUND OF THE INVENTION[0002]This invention relates to digital electronic controllers and, more particularly, to portable digital electronic load cell indicators.[0003]Measuring transducers are known in the art and are used to measure forces associated with any number of applications involving such things as weight, gravity, pressure, and vibration. A load cell is a common measuring transducer that is typically used in a wide variety ...

AI Technical Summary

Benefits of technology

[0016]It is therefore an object of the present invention to provide a digital electronic controller,

Problems solved by technology

Most have common weaknesses that present problems particularly when the load cell indicators are used in rough, washdown environments.

This high pressure spray will often seep past gaskets and seals, leaving the internal electrical connectors and electronic components wet.

Since the cleaning solutions used are typically slightly conductive, any solution that finds its way to the incoming AC power connector will often result in damage, which can range from minor corrosion of wiring and printed circuit board traces to arc-over and destruction of the AC power connector and related circuitry.

This damage often limits the useful life of an instrument to mere weeks.

If the indicator uses a plastic membrane keypad, which is by far the most common type of front panel found on load cell indicators, this activity will quickly result in a damaged keypad.

Depending on the design on the specific indicator, a damaged keypad may be replaced, or it may mean replacement of the entire indicator.

Again, this potential for damage limits the lifetime of indicators in some environments.

While this style of double enclosure mounting may reduce high pressure fluid infiltration in the indicator enclosure, it also limits operator access to the indicator, sometimes excessively so.

The effectiveness of this mounting style is frequently reduced by the tendency of operators to forget to latch the front lid, leaving the indicator exposed to the very high pressure spray the lid was intended to prevent.

The choice of display can be problematic, as many display types with outstanding visibility (such as a vacuum florescent display—VFD) have high power consumption.

Indicators that use VFDs often have no provision for running from battery power, limiting their usefulness as a portable device.

Other indicators use seven-segment light emitting diode (LED) displays, which provide good visibility and reasonable power consumption, but the seven-segment style of digit is not conducive to presenting alphanumeric data to the user.

Indicators with seven segment displays are thus limited in displaying information, which makes setup and troubleshooting cryptic and difficult.

However, many digital load cell indicators use LCD modules that require ambient light for the display to be visible to the user, which makes the instrument difficult to use in dark or uncertain lighting.

High temperature washdown followed by extended use in cold temperature environments can lead to condensation forming on the enclosure.

If the seals around the cables, display, and keypad are less than perfect, and they usually are, condensation can also form on the inside of the enclosure, which can wet the electronic components, circuit boards, and connectors.

Display fogging is also common in this situation.

These conditions conspir

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