Nine-position resistor ladder switch assembly

Abstract

A switch assembly is provided for use on a vehicle having a source of supply voltage. The assembly comprises a switching network having an input terminal configured to be coupled to the supply voltage and an output terminal. The network comprises: (1) nine series-coupled resistors coupled between the input terminal and the output terminal, each resistor having a substantially predetermined resistance; and (2) nine switches each coupled between the input terminal and the output terminal and capable of being opened and closed by an operator of the vehicle. Eight of the switches are each coupled to a different junction of adjacent resistors, and the ninth switch is coupled between the output terminal and the ninth resistor. The switch assembly further comprises a control module coupled to the output terminal for determining which, if any, of the nine switches is closed.

Description

TECHNICAL FIELD [0001] The present invention relates generally to resistor ladder networks and, more specifically, to a nine-position resistor ladder circuit for use in a vehicular switch assembly. BACKGROUND OF THE INVENTION [0002] As vehicles have developed over the years, the number of vehicular features and the ways in which those features may be adjusted (e.g., the number of feature modes) have increased dramatically. It is now common to provide a group of buttons or switches that a user (e.g., a driver) may utilize to adjust a vehicle's features to a preferential mode, and it is known to use resistor ladder networks in conjunction with these switches. Resistor ladder networks typically comprise a plurality of resistors and a plurality of switches disposed such that the closing of any one of the switches alters either the high resistance or the low resistance of a voltage divider circuit. The voltage divider circuit is comprised of a high resistance between a source of supply v...

AI Technical Summary

Problems solved by technology

For this and other reasons, resistor ladder switch assemblies have been limited in the number of switches that they may employ.

The problem is complicated due to supply voltage (e.g., battery) variations.

Additionally, other operational conditions experienced in the vehicular environment may cause fluctuations in the battery voltage and the voltages appearing at the output of the ladder networks, including extreme temperature variations (e.g., −40 to 80 degrees Celsius), vibrations, and corrosive agents.

The need to utilize separate four-resistor and five-resistor ladder networks providing first and second output voltages, respectively, results in a more complex, costly, and cumbersome system.

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