GB2219138A

GB2219138A - Waterproof switch

Info

Publication number: GB2219138A
Application number: GB8812652A
Authority: GB
Inventors: Sai Wing Wong
Original assignee: KWAN HING IND CO Ltd
Current assignee: KWAN HING IND CO Ltd
Priority date: 1988-05-27
Filing date: 1988-05-27
Publication date: 1989-11-29
Also published as: GB8812652D0

Abstract

A battery-operated, hand-held appliance (e.g. a torch) has an on/off switch sealed from the atmosphere, the switch mechanism comprising one or more electrical switch contacts formed of magnetic material, a magnet 9 located adjacent the electrical switch contacts and an on/off actuator 3 located on the outside of the appliance comprising a slide housing two magnets 4, 5 with poles in opposition directions, movable between a first "off" position and one or more "on" positions, the flux from one of the magnets 4, 5 passing through the casing and causing the switch contacts to move between the "on" and "off" positions depending upon the position of the actuator. Magnet 9 attracts contact strip 10 from the contact point 7 to ensure the appliance is switched off. Magnet 4 counters interference due to magnet 9. <IMAGE>

Description

IMPROVENERS IN WATERPROOF SWITCHES The present invention relates to a water-proof switch for a hand-held, battery-operated appliance.

It is desirable for hand-held, battery-operated appliances that may be used or stored in a wet or damp environment that the casing thereof is completely waterproof. One area of such appliances which may permit the egress of water or damp air is the on/off switch.

Hand-held, water-proof battery-operated flashlights or torches are known in which the actuator for the switch, located on the outside of the casing, carries a magnet and when said switch actuator is positioned in the "on" position magnetic flux from the magnet passes through the housing and causes the switch contacts inside to close so causing electricity to flow from the batteries to the light-emitting device. In the "off" position the switch contacts are out of the sphere of influence of the magnetic flux and so the switch is "off" and no electricity flows.

It has been found however that after a while the switch contacts become "stuck" in the closed i.e. "on" position and it becomes necessary to move the switch actuator rapidly several times between the "on" and "off" positions to break the contact and so turn off the power supply to the light-emitting device.

Accordingly we have sought to provide a battery-operated, hand-held appliance which is provided with a water-proof switch in which such problems do not arise.

Accordingly the present invention provides a battery-operated, hand held appliance comprising a water-tight casing with an on/off switch mechanism sealed from the atmosphere, the switch mechanism comprising one or more electrical switch contacts located within the casing and formed of magnetic material for controlling the actuation of the function or functions of the appliance, a magnet located adjacent the electrical switch contacts and an on/off actuator located outside the casing, the on/off actuator comprising a slide housing two magnets positioned with their respective poles in opposition directions, movable between a first position and one or more other positions, in the first position of the actuator the electrical switch contacts are in the "off" position and in the other position or positions the electircal switch contacts are in the "on" position, the magnetic flux from one of the magnets in the actuator passing through the casing and causing the electrical switch contacts to move between the "on" and "off" positions depending upon the position of the actuator.

The invention will now be described by way of example with reference to the accompanying drawings, in which Figure 1 is a vertical cross-section through the switch of a hand-held appliance with the appliance in the "off" position, and Figure 2 is a vertical cross-section through the switch of figure 1 with the appliance in the "on" position.

The switch shown generally as 1 in Figures 1 and 2 forms part of a hand-held, battery-operated appliance such as a flash light or torch. A portion of the casing of the hand-held, battery-operated appliance is shown as 2.

An actuator 3 (not visible in Figure 1) for the switch is located on the outside of the casing 2 and houses two permanent magnets 4 and 5 with their poles in opposite direction as shown. A printed circuit board 6 with one or more contact points 7 is located beneath the casing 2.

Located below the printed circuit board 6 is a support 8 formed of copper on which is mounted a permanent magnet 9.

A contact strip 10 is located within the appliance and is formed of a magnetisable material such as iron and is resiliently biased away from the contact points 7 on the printed circuit board 6 in the "off" position 6.

As shown in Figure 2 the actuator 3 has been moved along the casing 2 so that magnet 5 is located above contact point 7. The magnetic flux from magnet 5'attracts one end 11 of the contact strip 10 into contact with contact point 7 to complete the circuit from the batteries (not shown) to the functioning point of the appliance e.g.

light bulb (not shown). The permanent magnet 9 serves to provide a magnetic.flux to attract the contact strip 10 away from the contact point 7 as the actuator is moved back to the "off" position so as to ensure the appliance is cleanly "switched off", since after a period of time it has been found that the resilience of contact strip 10 is not sufficient to ensure that the contact between end 11 and contact point 7 is broken and end 11 tends to stay in contact with the contact point 7 even when the actuator 3 is in the "off" position.

However without the presence of permanent magnet 4 in the actuator, the magnetic flux from magnet 9 tends to interfere with the contacting of contact strip 10 and contact point 7 so by having magnet 4 in actuator 3 with its polarity opposite to that of magnet 3 such interference is overcome.

Claims

WHAT WE CLAIM IS:

1. A battery-operated, hand held appliance comprising a water-tight casing with an on/off switch mechanism sealed from the atmosphere, the switch mechanism comprising one or more electrical switch contacts located within the casing and formed 'of magnetic material for controlling the actuation of the function or functions of the appliance, a magnet located adjacent the electrical switch contacts and an on/off actuator located outside the casing, the on/off actuator comprising a slide housing two magnets positioned with their respective poles in opposition directions, movable between a first position and one or more other positions, in the first position of the actuator the electrical switch contacts are in the "off" position and in the other position or positions the electrical switch contacts are in the "on" position, the magnetic flux from one of the magnets in the actuator passing through the casing and causing the electrical switch contacts to move between the "on" and "off" positions depending upon the position of the actuator.

2. An appliance as claimed in claim 1, which is a flash light or torch.

3. An appliance as claimed in claim 1 substantially as herein described and with reference to the accompanying drawings.