GB2333589A

GB2333589A - Illuminated optical switch

Info

Publication number: GB2333589A
Application number: GB9801493A
Authority: GB
Inventors: Joachim Fricke; Peter Miller
Original assignee: Motorola Ltd
Current assignee: Motorola Solutions UK Ltd
Priority date: 1998-01-24
Filing date: 1998-01-24
Publication date: 1999-07-28
Also published as: GB9801493D0

Abstract

An electronic user operated switch arrangement has a housing, an LED 30 and a light detector 40 arranged at opposite ends of an optical path. A switch actuator 50 is mounted in the optical path between the LED 30 and the detector 40 and is moveable between a first position and a second position. The switch actuator includes an illumination arrangement for providing light from the LED to illuminate 65 the switch arrangement, and a blocking member arranged to selectively block the light to the detector in dependence upon the position of the switch actuator.

Description

AN ELECIRONIC USER OPERATED SWITCH ARRANGEMENT Field of the Invention This invention relates to electronic user operated switches, and particularly but not exclusively to switches for use in Moulded Interconnect Devices (MID's).

Background of the Invention MID technology is concerned with the combination of electrical and mechanical features into a single electronic module, thereby reducing the number of parts and connections required.

A problem with this technology, particularly in applications suitable for the Automotive industry, is the requirement for suitable input and output devices. For example, an electronic module designed to operate a servo such as an electric window motor, requires a user operated for opening and closing the window. Ideally this switch should be integrated with the module.

A problem with this arrangement is that switches cannot easily be incorporated on a printed-circuit-board (PCB) substrate, and they add complexity and cost when incorporated into MID devices, particularly if more than one user operated switch is required in a module.

Furthermore, typically user operated switches require a separate illumination arrangement so that the user can easily locate them in the dark. This adds further complexity and cost.

This invention seeks to provide an electronic user operated switch arrangement which mitigates the above mentioned disadvantages.

Summarv of the Invention According to the present invention there is provided an electronic user operated switch arrangement comprising: a switch housing; a light emitting arrangement mounted in the housing and arranged to emit light along an optical path; a light detecting arrangement mounted in the housing and arranged to detect light in the optical path; and a switch actuator, mounted in the optical path between the light emitting arrangement and the light detecting arrangement, the switch actuator being moveable between a first position and a second position and arranged to be actuated by a user, wherein the switch actuator includes illumination means for providing at least a portion of the light to illuminate the switch arrangement, and a blocking member arranged to selectively block the light to the light detecting arrangement in dependence upon the position of the switch actuator, thereby defining first and second states of the switch respectively.

In this way a switch arrangement is provided which can be easily integrated in the PCB, and which combines actuation and illumination functions using a minimum number of components.

Brief Description of the Drawings An exemplary embodiment of the invention will now be described with reference to the drawing in which: FIG. 1 shows a first configuration of a preferred embodiment of an electronic user operated switch arrangement in accordance with the invention.

FIG. 2 shows the preferred embodiment of FIG. 1 in a second configuration.

FIG. 3 shows a detailed view of part of the preferred embodiment of FIG. 1.

Detailed Description of a PrArSred Embodiment Referring to FIG.1, there is shown an electronic user operated switch arrangement 10, formed in part of an MID module. The arrangement 10 includes a PCB 20, a light emitting diode (LED) 30, a light detector 40, a movable member 50 and a membrane 60.

One side of the PCB 20 also forms part of the outer housing of the MID module, and the other side is electrically and physically connected to the LED 30 and the detector 40, such that an optical path 55 is formed therebetween.

The LED 30 receives power from the PCB 20 and is arranged to provide light along the optical path. The detector 40 also receives power from the PCB 20 and is arranged to detect incident light received from the optical path and to provide a signal to the PCB 20 in dependence upon detection of light propagating along the optical path 55.

Referring now also to FIG. 3, the movable member 50, which is arranged to actuate the switch, is disposed in the optical path 55 and has an upper surface 65 in contact with the membrane 60. The upper surface is at least partially translucent.

The movable member 50 has a first section 75, having a light steering arrangement formed by a reflection surface. The movable member 50 has a second section 85, having an aperture 80 extending through the movable member 50.

In operation, the switch arrangement 10 has two states. In a first (off) state, the first section 75 of the movable member 50 intersects the optical path 55, such that the light is reflected at the reflection surface 70 and is incident on the translucent upper surface 65 of the movable member 50, where it is visible to the user through the membrane 60, as shown in FIG.

1. In the first state, the light detector 40 does not detect any incident light, and therefore no signal is sent to the PCB 20.

Referring now also to FIG. 2, a user operates the switch arrangement 10 by pressing the membrane 60 as shown by the arrow 90, causing the movable member 50 to move downwards such that the second section 85 of the movable member 50 now intersects the optical path 55, as shown in FIG. 2 This defines a second (on) state of the switch arrangement 10. In this second state, the light from the LED 30 passes through the movable member 50 by virtue of the aperture 80, and is detected by the light detector 40, which sends a signal to the PCB 20.

The movable member 50 may be arranged with a return spring arrangement (not shown), such that after pressing the membrane 60, the movable member 50 will rise again, returning the switch arrangement to the first (off) state.

It will be appreciated that alternative embodiments to the one described above are possible. For example, the aperture 80 could be replaced with a semi-reflective arrangement, such that a portion of the incident light is reflected up to the upper surface 65 of the movable member 50 during the second state. In this way the switch arrangement 10 will remain illuminated during both states, the difference between the first and second states being discernible from the brightness of the light visible through the membrane 60.

Furthermore, the LED 30 could be a bi-colour LED, which switches between first and second coloured light in dependence upon the state of the switch arrangement 10, in order to provide an indication to the user of the state of the switch arrangment 10.

It is also envisaged that an arrangement having more than one switch is possible, using a number of movable members and either a single LED with multiple detectors, or multiple LED's which are pulse-coded, with a single detector.

Claims

Claims 1. An electronic user operated switch arrangement comprising: a switch housing; a light emitting arrangement mounted in the housing and arranged to emit light along an optical path; a light detecting arrangement mounted in the housing and arranged to detect light in the optical path; and a switch actuator, mounted in the optical path between the light emitting arrangement and the light detecting arrangement, the switch actuator being moveable between a first position and a second position and arranged to be actuated by a user, wherein the switch actuator includes illumination means for providing at least a portion of the light to illuminate the switch arrangement, and a blocking member arranged to selectively block the light to the light detecting arrangement in dependence upon the position of the switch actuator, thereby defining first and second states of the switch respectively.
2. The switch arrangement of claim 1 wherein the illumination means includes a light steering arrangement and an illumination surface visible to the user, the light steering arrangement being arranged to direct at least a portion of the light to the illumination surface.
3. The switch arrangement of claim 2 wherein the light steering arrangement is a reflection surface.
4. The switch arrangement of any preceding claim wherein the switch housing incorporates an integral printed circuit board, to which the light emitting and light detecting arrangement are connected.
5. The switch arrangement of any preceding claim further comprising at least one further switch actuator and at least one further light detecting arrangement, arranged to operate in conjunction with the light emitting arrangement.
6. The switch arrangement of any preceding claim further comprising at least one further switch actuator and at least one further light emitting arrangement which is pulse coded with the light emitting arrangement, arranged to operate in conjunction with the light detecting arrangement.
7. An electronic user operated switch arrangement substantially as hereinbefore described and with reference to the drawings.