GB2244129A

GB2244129A - Warning light

Info

Publication number: GB2244129A
Application number: GB9108031A
Authority: GB
Inventors: Laszlo Hamar
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-04-25
Filing date: 1991-04-16
Publication date: 1991-11-20
Also published as: GB9108031D0; GB9009260D0

Abstract

A warning light arrangement preferably for a motor vehicle including a light sensitive sensor 12, switching means 16 and a lighting array 20, 22 which may be provided by a vehicles existing lights, for example, side lights, or brake lights. When the sensor is acted on by the lights of an oncoming vehicle the switching means causes the light array to be illuminated thereby indicating the presence of the vehicle carrying the sensor. A timing mechanism (not shown) may be included to deactivate the light array after a predetermined time period has elapsed from activation. <IMAGE>

Description

WARNING LIGHT This invention relates to a warning light especially for vehicles operative to be effective only when such warning is required.

Warning lights intended, for example, to warn or mark the presence of a stationary vehicle for other road users are already known. Commonly these lights are wired into vehicle ignition circuitry and must be left in either an on or an off condition. One of the problems inherent in this arrangement is that when a vehicle is left unattended for a long period of time a light left in the on condition may drain a large proportion of the vehicle's battery capability thus leaving insufficient charge to start the vehicle's engine.

A further problem is that the warning light must be either fully on or fully off for all its operable period.

Thus the warning light is not responsive to a change in visibility conditions which may require its use after it had been placed in an off condition or alternatively the warning light will not be switched off where its use is no longer required due to an absence of traffic in the vicinity of the vehicle.

It is object of the invention therefore to provide a vehicle warning light arrangement which is effective to conserve a vehicle's battery charge and to be operated only when required to warn other road users of the presence of a stationary vehicle.

With this object in view the present invention provides a warning light arrangement including a sensor connected to a lighting arrangement such that the lighting arrangement will be operated only when the sensor detects the presence of an approaching vehicle.

Preferably the sensor is a light sensor operative to detect lights of the approaching vehicle although other sensors, for example, ultrasonics etc. may also be usable. The light sensor may be a light dependent resistor or a photo-transistor. Advantageously the sensitivity of the resistor is variable so that the sensor can be adjusted for range and ambient light conditions.

It will be understood that with such an arrangement, a vehicle provided with such a warning light arrangement may be left in a parked condition with the arrangement switched on and the vehicle's lights will only be activated as a warning when the presence of an approaching vehicle's lights are detected by the light sensor. Thus the lighting arrangement is not in use at all times and is directly responsive to the amount of traffic passing the parked vehicle.

In a first preferred aspect of the invention, the vehicle warning light arrangement comprises a light sensor located at the rear of the vehicle and connected by switching means to the vehicle's existing lighting arrangement, the switching means being effective to operate the lighting arrangment when the light sensor detects a light source directed towards the sensor.

It will be appreciated that in this aspect of the invention the warning light arrangement makes use of the vehicle's existing light arrays, for example, side lights or brake lights which are caused to be actuated when the sensor is operated. Preferably a time delay mechanism is provided within the switching means such that operation of the lighting arrangement will be maintained for a predetermined short period of time after the light source is no longer directed towards the light sensor. In this way any sudden obscuring of the light source will not automatically result in a switching off of the lighting arrangement.

In a preferred modification the vehicle's lighting arrangements, both front and rear, are actuated by operation of the switching means such that the vehicle is illuminated from all directions. In this instance it may be preferable to provide an additional sensor located at the front of the vehicle, particularly where the road width adjacent to the parked vehicle is relatively narrow.

In an alternative aspect of the invention, a combined vehicle warning light arrangement is provided comprising a housing enclosing a light sensor and a lighting arrangement, the arrangement and the sensor being connected by switching means operative to activate the lighting arrangement when the sensor is acted upon by a light source.

It will be understood that with such a modified arrangement the enclosed unit may be mounted in the rear or front window of a vehicle as desired in a manner of known additional brake light units.

Alternatively, the housing may be mounted on the vehicle's exterior. However, this would lead it vulnerable to external forces, for example, collisions and also to theft or similar actions.

In order to ensure that the sensor is not actuated for long periods by an increase in light impinging thereon, e.g. as would be caused by an adjacent car parked with its lights on or an adjacent building light, the arrangement preferably includes a comparator having an initially pre-set light value which will cause the light to be switched on when the value is exceeded, the comparator including means to alter the pre-set value to preferably equal the light value sensed by the sensor, when the original preset value is exceeded for a predetermined time period.

Additionally the comparator also includes means to re-set the light value to its original pre-set value when the light value sensed by the sensor falls below the current value for a predetermined time period.

The invention will now be described further by way of example with reference to the accompanying drawing in which the single figure is a block diagram of a first preferred embodiment of the invention.

Referring to the accompanying drawing, a preferred embodiment of the invention provides a vehicle warning light arrangement 10 including a light sensitive sensor 12, for example, a light sensitive diode, photo transistor or other similar light sensitive detector operative to measure the amount of light impinging on the sensor and produce an electrical signal proportional to that light value. The sensor 12 is connected to an enable switch 14 which enables the system operator to determine whether the system is in an on or off mode. The sensor is further connected to switching means 16 which are connected to a battery 18 which may be either the vehicle's own normal battery source or may be a supplementary battery connected solely to this arrangement.

The switching means 16 are also connected to at least one lighting arrangement or array 20, 22. In one embodiment of the invention this lighting arrangement 20 is an additional light intended solely for the purpose of warning other vehicles of the presence of the stationary vehicle. In an alternative embodiment the light 20 may be the vehicle's own existing lights, for example, side lights, rear lights or brake lights etc.

It will be appreciated that with the enable switch 14 operated to activate the system the sensor 12 is operative to detect the lights of any vehicle approaching the sensor. When the sensor 12 detects this condition it operates the switching means 16 enabling the lighting arrangement 20 to draw power from the battery 18 and hence illuminate the parked vehicle. Although the enable switch 14 for the sensor will be activated for the entirety of the period during which the vehicle is parked, the battery 18 will not be required to power the light or lights 20, 22 during this period and hence battery charge will be conserved.

The switching means 16 includes a comparator 24 which compares the light value measured by the sensor 12 with a predetermined value stored in the comparator. The predetermined value is preferably set by an external controller (not shown) such that adjustments can be made for required range and ambient light conditions. If the sensor's measured value exceeds the predetermined value the comparator actuates a second switch 26 and operates the light array 20, 22 to illuminate the parked vehicle.

In order that the pre-set value may be sensitve to a change in ambient light conditions i.e. an increase due to an adjacent building light being switched on, the comparator preferably also includes a timing unit 28 which will measure the time period for which the measured light value exceeds the pre-set value. Where this time period exceeds a predetermined period, for example, thirty seconds, the timing unit 28 generates an output to the comparator 24 to re-set the predetermined light value stored therein to a new value equal to the current measured value. In this way a relatively long term increase in light received by the sensor 12 will not cause the arrangement to be permanently on".

In such an embodiment the switching means will also include a second comparator 30 which also receives the outputed measured light value from the sensor 12. This second comparator 30 is activated when the pre-set value of the first comparator 24 is altered and is operative to compare the measured light value with the original prestored value. When the measured value falls below the original pre-stored value the second comparator 30 acts to re-set the value stored in the first comparator 24 to its original level. Thus when the reason for an increase in ambient light is removed the arrangement is re-set to its original condition.

It is possible to present the vehicle warning light arrangement in two alternative embodiments. Firstly, the entire system, sensor 12, enable switch 14, switching means 16, battery 18 and lights 20, may be provided in a casing or housing (not shown) which is provided with fixing means for attaching to the vehicle.

This self-powered assembly could be mounted inside the rear window of the vehicle or to a rear bumper.

Alternatively, the sensor means could be mounted remote from the lighting arrangement and switching , for example, the sensor could be provided on or adjacent to the vehicle's bumper or again inside the rear window of a vehicle and attached to the vehicle's normal lighting arrays. In this instance it would probably be advantageous for the sensor and the lights to draw power from the vehicle's own battery and this would, of course, simplify connection of the system to the vehicle's existing electrical system.

In order that the light on the vehicle should not be turned off immediately a light source no longer impinges on the sensor, a time delay factor may advantageously be included in the switching means so that the light 20 remains illuminated for a short predetermined period after the sensor is no longer acted upon by a light.

It will be appreciated that by utilisation of either of the two described embodiments the vehicle warning light arrangement according to the invention provides a system which is both reponsive to traffic conditions and operative to conserve battery charge during periods when illumination of the vehicle is not required.

The invention is not confined to the foregoing details and variations may be made thereto within the scope of the invention. For example, the sensor 12 may be any conenient detector operative to sense the presence of an approaching vehicle, thus ultrasonics or radar type systems may be used as an alternative to a light sensor.

In addition to its use on motor vehicles the invention can also be used on caravans or trailers or on stationary road signs where periodic illumination is desirable. Other variations may also be possible.

Claims

1. A warning light arrangement including a sensor connected to a light array such that the lighting arrangement will be operated when the sensor detects the presence of a vehicle approaching the warning light arrangement.

2. A warning light arrangement as claimed in Claim 1 in which the sensor is a light sensor operative to detect lights of the approaching vehicle.

3. A warning light arrangement as claimed in Claim 2 comprising a light sensor located at the rear of a vehicle and connected by switching means to the vehicle's existing lighting array, the arrangement further including switching means effective to operate the lighting array when the light sensor detects a light source directed towards the sensor.

4. A warning light arrangement as claimed in any preceding claim in which the light array is a vehicle's existing light array which is caused to be actuated when the sensor is operated.

5. A warning light arrangement as claimed in any preceding claim in which a time delay mechanism is provided within switching means such that operation of the lighting array will be maintained for a predetermined period of time after a vehicle is detected by the sensor.

6. A warning light arrangement for a vehicle comprising a housing enclosing a light sensor and a lighting arrangement, the arrangement and the sensor being connected by switching means operative to activate the lighting arrangement when the sensor is acted upon by an external light source.

7. A warning light arrangement as claimed in claims 3, 4 or 5 in which the switching means includes a comparator having stored therein a first predetermined reference light value, the comparator being operative to actuate the lighting array when the first reference value is exceeded by sensor's measured value, the switching means also including means to alter the first reference light value to a second reference value when it is exceeded by the measured value for a predetermined time period.

8. A warning light arrangement as claimed in claim 7 in which the second reference value is substantially equal to the sensor's current measured value.

9. A warning light arrangement as claimed in claims 7 or 8 in which the second reference value is altered back to the first reference value when the sensor's measured value falls below the second reference value for a second predetermined time period.

10. A warning light arrangement substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.