A LIGHT

Abstract: Previously it has been difficult to see cyclists in the dark. It was particularly difficult to see cyclists as they slowed down if their bicycles were equipped with dynamo powered lights. The invention provides a safety light (10) wich illuminates, on activation of an inertia switch (27), when a cyclist slows down. In an alternative embodiment the light (10) may be used as a safety feature for use in a car, in case the brake lights fail. Preferably a delay device is incorporated which ensures the light (10) remains on for a minimum period, even after the inertia switch (27) has been deactivated.

Description: TITLE A LIGHT BACKGROUND OF THE INVENTION This invention relates to a light and more particularly it relates to a light for use on a vehicle, which may be a bicycle. PRIOR ART In the past it has not always been easy to see cyclists in the dark. A reason for this was because of the relatively low intensity of the cyclist's rear warning light. It .can be especially difficult to see a cyclist when the bicycle has a dynamo powered rear warning light. This is because as the cyclist slows, the amount of light decreases. This has been a problem for cyclists when approaching junctions or cross-roads. Another disadvantage of some types of cycle rear warning light has been that, because of its relatively low intensity, it has only been of any use when it is seen against a relatively dark background. Thus, although the cyclist's rear light may be on, if the ambient light level is relatively high, for example at dusk, or if the prevailing weather conditions are foggy the cyclist's rear light may not be easily spotted by an oncoming car . BRIEF DESCRIPTION OF THE INVENTION According to the present invention there is provided a light which comprises a body containing an energy source, a light source and an inertia switch, such that the inertia switch is arranged to activate the light source on deceleration of a -vehicle on which the light is supported. Preferably two filaments are provided such that one is independent of the inertia switch. This enables the light to be used as a permanent warning light, as well as a safety stop, or brake, light. Because of the independent energy source and the inertia switch light has been produced when the bicycle slows. Thus more light is produced when it is needed as a warning light, contrary to what has happened in the past with the dynamo powered warning light. Means may be provided to vary characteristics of the inertia switch so as to accommodate for heavier or lighter bicycles and/or cyclist. The inertia switch may be a mecury tip switch, in which case the angle of inclination of the switch may be varied to achieve this. Preferably two separate light bulbs are provided within the body of the light, the first being connected to an independent energy source so as to provide a permanent light. The second is connected, via the inertia switch to its own energy source so as to form the stop light. A single switch may be arranged such that it operates both circuits concurrently. However, in a preferred embodiment separate switches may be provided for each of the two circuits . The advantage of providing separate switches is apparent when considering that the permanent light will only be required when it is dark, whereas the stop light, because it is not always energised, may be permanently switched on, for cycling during the day and night. Preferably the two light bulbs are provided within separate compartments of the body of the light. Each bulb has its own reflector and coloured lens cover. Both of these lenses are red. Because the light has its own independent energy source, it may be mounted towards the rear of a vehicle, such as a car. Such an arrangement may be considered as an additional safety stop light as it would be independent of a car's braking and electrical system. The light has its own power supply which may be achieved with long life batteries or rechargeable batteries linked to the car's alternator. Such an arrangement will operate if a car's brake lights fail to work or if there is an electrical fault in the car. The light could also be arranged to activate if the car was simply decelerating without the driver actually braking. The light is preferably mounted on the rear shelf of a vehicle or is attached to the rear window of a car by way of a rack which allows the angle of inclination of the light to be set to a variable degree so that it may be clearly seen from a driver's eye level from a vehicle following. The inertia switch may incorporate a different conductive liquid other than mercury. Alternatively the inertia switch may be a mechanical device which contacts an electrode when activated. Such an embodiment may comprise a resiliently deformable tab or a sprung electrode. Advantageously a delay device is provided, to maintain the light in an activated state for a predetermined time period. This could comprise a delay circuit, or a mechanical damper, which when triggered would ensure that the light remained in an on state, even if decelaration was only momentary and was followed by a rapid acceleration. Without such a delay device the light may flicker on for a very short period and may not be seen by an oncoming vehicle. However, with such a device the light will remain energised for a pre-determined minimum time period, which is preferably three seconds. The delay device is preferably electronic and comprises a capacitor which charges when the device is activated on deceleration, and discharges when it is deactivated, i.e. on acceleration. Embodiments of the present invention will now be described by way of examples only, and with reference to the accompanying figures, in which:- BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows a plan view of a light; Figure 2 shows a longitudinal sectional view along line A-A of figure 1; Figure 3 shows a transverse sectional view along line B-B of figure 1; Figure 4 shows a transverse sectional view along line C-C of figure 1; Figure 5 shows a rear inside view of the light of figure 1; Figure 6 is a circuit diagram of a circuit for use with the ligh ; and Figure 7 shows a sectional view of an alternative light. DETAILED DESCRIPTIONS OF THE INVENTION Referring to the figures a light shown generally at 10 comprises a body 11 formed from a synthetic plastics material. Lenses 12 and 13 are integrally moulded on a plastics lens support 14. The lenses 12 and 13 are formed from a clear plastics material which is red and which has been embossed with a retro-reflective patterned surface so as to focus light in a generally backward direction when the light 10 is fitted to the rear of a bicycle or vehicle (not shown). Figure 2 shows front cover guard 14 which is clipped onto the body 11 by way of upper and lower clips 15a and 15b respectively. A light bulb 16 is housed within an upper portion of the light 10, at the focus of a silvered parabolic reflecting surface 17. Light bulb 18 is housed within a lower portion of the light 10 at the focus of a similar reflective silvered parabolic surface 19. The parabolic silvered surfaces 17 and 19 are formed integrally with a single support body 20. Associated with each light bulb 16 and 18 there is a resiliently sprung material 21 and 22 respectively. These springs 21 and 22 serve to urge the light bulbs 16 and 18 respectively through orifices 23 and 24 of the support body 20 respectively. Collars on the light bulbs 16 and 18 prevent the light bulbs 16 and 18 from falling through the orifices 23 and 24. The collars provide electrical contact with the body 20. Suitable Nickel/Cadmium or dry cells 25a and 25b are inserted within the body 11 in the prescribed manner, so that on depression of switch 26 the light bulb 16 will come on and illuminate in a generally rearward direction. Referring to figures 3, 4 and 5, in which inertia switch 27, is shown together with dry cells 28a, 28b, 28c and 28d and bulb 18 in the lower portion of the body 11 and cells 25a and 25b are in the upper position of the body 11. The lower portion acts as the stop light. The inertia switch 27 is connected in series with the cells 28 and the bulb 18. On deceleration of the vehicle, on which the light 10 is supported the inertia switch 27, shown as 43 in figure 6, closes the circuit, and illuminates the light bulb 18. A delay circuit 40, shown in detail in figure 6, may be incorporated into the light 10 so that even if the inertia switch 27 is activated momentarily, the delay circuit 40 will cause the bulb 18 to remain on for a longer period, as described below. The duration of this delay may be preset by selecting the types of components, in particular the capacitance of capacitor 42 may be increased so as to provide for a relatively long period of illumination after decelaration has ceased. The operation of the delay circuit will now be described with reference to figure 6. The delay circuit 40 comprises transistor 44 which is arranged to switch transistor 45 on, when the inertia switch 43 (27 in figures 1 to 5 and 7) is activated. The bulb 18 is then switched on. Current flows through limiting resistor 41a and charges capacitor 42 during the period when the inertia switch 43 is activated. On acceleration of the vehicle, the inertia switch is deactivated and capacitor 42 discharges through resistor 41b holding transistor 44 in an on state. The base of transistor 45 is held on by transistor 44 and thus conducts enabling bulb 18 to be energised. This continues until capacitor 42 has discharged to a level whereby it cannot maintain the transistors 44 and 45 switched on. The light then is extinguished from the bulb 18. Figure 7 shows an alternative embodiment of the light 50 which is adapted to be used in a rear window 49 of a vehicle such as a car, van or caravan. The light 50 is mounted on a bracket 50a which has a ratchet mechanism 51 to vary the angle of lens 52 pointing backwards. The light 50 has similar delay switch 55 to that described with reference to figures 1 to 5. A separate energy source (not shown) is provided within the body of the light 50. The same reference numerals have been used in figure 7 as in the previous figures. It will be appreciated that variation to the above embodiments may be made without departing from the scope of the invention.

Claims: CLAIMS 1. A light comprising a body containing an energy source, a light source and an inertia switch, such that the inertia switch is arranged to activate the light source on deceleration of a vehicle on which the light is supported. 2. A light according to claim 1 wherein the inertia switch comprises a conductive liquid. 3. A light according to claim 2 wherein the conductive liquid is mercury. 4. A light according to claim 1 wherein the inertia switch comprises a mechanical device. 5. A light according to claim 4 wherein the inertia switch comprises a resiliently sprung contact. 6. A light according to any preceding claim having two light sources, each light source having an independent energy source, the inertia switch being associated with one of the light sources only. 7. A light according to claim 6 wherein one of the light sources has associated with it a delay circuit arranged such that the light source will be maintained in an energised state for a period longer than the period during which the associated inertia switch is activated. 8. A light according to claim 7 wherein the delay device comprises a capacitor arranged to discharge, when the inertia switch is deactivated, through at least one transistor thereby maintaining the transistor and the associated light source in a switched on state. 9. A light according to any preceding claim wherein the inertia switch may be adjusted for use with vehicles of different masses. 10. A light according to any preceding claim for use as a safety light on a bicycle. 11. A light according to any of claims 1 to 8 for se as a safety light in a car.

Inventors: MARSDEN VALERIE JEAN ELIZABETH, MARSDEN, VALERIE, JEAN, ELIZABETH
Applicants: MARSDEN VALERIE JEAN ELIZABETH, MARSDEN, VALERIE, JEAN, ELIZABETH
Application year: 1991
Main classification: B60Q1
IPC codes: B60Q1, B62J6