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LOW COST MEMBRANE SWITCH DESIGN

IP.com Disclosure Number: IPCOM000005525D
Original Publication Date: 1984-Apr-01
Included in the Prior Art Database: 2001-Oct-11
Document File: 3 page(s) / 97K

Publishing Venue

Motorola

Abstract

Conventional design membrane switches are normally constructed using multiple switch layers. Each layer serving as the backing or carrier for a portion of the matrix circuit. Each layer has a connecting tail to carry switching information to a circuit board through a connector. In assembly the switch layers are spaced apart and adhesively bonded together with a"spacer."This element is designed with apertures aligned with the switching positions screened on the switch layers and allows different portions of the switch circuit carried on each layer to be shorted together at the aperture locations with mechanical finger pressure. The schematic for a conventional membrane switch is shown in Figure 1 and is referred to as a standard X-Y matrix.

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MOTOROLA Technical Developments Volume 4 April 1984

LOW COST MEMBRANE SWITCH DESIGN

   Conventional design membrane switches are normally constructed using multiple switch layers. Each layer serving as the backing or carrier for a portion of the matrix circuit. Each layer has a connecting tail to carry switching information to a circuit board through a connector. In assembly the switch layers are spaced apart and adhesively bonded together with a"spacer."This element is designed with apertures aligned with the switching positions screened on the switch layers and allows different portions of the switch circuit carried on each layer to be shorted together at the aperture locations with mechanical finger pressure. The schematic for a conventional membrane switch is shown in Figure 1 and is referred to as a standard X-Y matrix.

Y,

              Figure 1 A standard 3x4 matrix. Provides 12 switch positions. The circuit for all "Y" lines is carried on switch layer #I. The circuit for all "x" lines is carried on switch layer #2.

   A variation of this design that is commonly seen is called a "folded" matrix switch. In this design all matrix lines enter one tail. The "x" lines are located at each end of the tail and travel across layer #l, the bridges and terminate on layer #I2 in the required circuit configuration. The"Y" lines are placed inside the "X" lines on the tail and terminate on layer#l. This type of switch is folded at the bridges on assembly so the layers align and is adhesively...