GB2351858A

GB2351858A - Vehicle deceleration indicator

Info

Publication number: GB2351858A
Application number: GB9915776A
Authority: GB
Inventors: Robert Keith Jordan
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-07-07
Filing date: 1999-07-07
Publication date: 2001-01-10
Also published as: GB9915776D0

Abstract

The vehicle warning system has an accelerometer 1 for measuring the deceleration of a vehicle. The filter 2 serves to filter noise signals from the accelerometer e.g. caused by bumps in the road, and the gain 2 controls the sensitivity of the deceleration measured. Microcontroller 3 controls a set of indicator lights in response to the report signal from the filter and gain network such that a visual indication is given of the degree of deceleration. The display is formed from a series of LED's and may be on the form of a triangle, the number of lights lit giving an indication of the degree of deceleration. The most severe deceleration level is accompanied by a flashing routine and the lights may also be used as a flashing hazard warning. The lights may operate only with the brake.

Description

2351858 VEHICLE WARNING SYSTEM This invention relates to a vehicle warning

system to warn when a vehicle is decelerating.

Most road vehicles have two or more rear brake lights which illuminate when the vehicles' brake pedal is depressed.

This warns any vehicle following that the vehicle is braking. These lights do not however indicate if the braking is a small deceleration such as a vehicle might make before cornering, a very large deceleration such as an emergency stop, or a deceleration somewhere between these extremes.

It is an object of the present invention to obviate or mitigate ths problem.

According to the present invention there is provided a vehicle warning system comprising an accelerometer, a control system connected to the accelerometer to provide a signal indicative for each of at least two levels of deceleration, and visual display means driven by the control system to display images representing any one of said two or more levels of deceleration.

Preferably the control system is a microcontroller. The microcontroller may provide nine signals indicative of nine levels of deceleration.

At least one of said control system signals may cause the 5 visual display means to flash.

The visual display means may be in the form of an array of lights. The lights may be LED's. The LED's may be arranged in the shape of a triangle. Preferably the number of lights in the array illuminated is indicative of the rate of deceleration of the vehicle.

The visual display means may be further controlled by the brake system of the vehicle whereby the visual display means can operate only when the brake pedal is operated.

The accelerometer may be connected to the control system through an electronic filter whereby the visual display means is not greatly affected by the condition of a surface the vehicle is travelling on.

The accelerometer may be connected to the control system through a gain control to adjust the levels of deceleration at which said signals are generated.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which:

Figure I shows a block circuit diagram; Figure 2 shows a front schematic view of a visual display means; Figure 3 is shows a modified display means; and Figure 4 illustrates a control circuit.

Referring to Figure 1, there is shown a circuit diagram of a vehicle-warning system. The system comprises an accelerometer 1, a filter and gain network 2, a control system in the form of a microcontroller 3, a display driver 4 and a visual display 5. All these components may be located in a common housing (not shown) to sit adjacent the inside of a vehicle rear windscreen, or other visible rear part of a vehicle.

The accelerometer 1 may be a solid state device of a type well known and is designed to measure the deceleration of the vehicle as it travels along a surface such as a road. The filter 2 serves to filter signals from the accelerometer caused by the surface condition such as bumps in the road. The gain 2 controls the sensitivity or the levels of deceleration measured.

The microcontroller 3 converts analogue signals from the accelerometer, as adjusted by the filter and gain network, into sequential digital signals indicative of nine levels of deceleration. These nine levels are provided by a lookup table in the microcontroller software which sets the deceleration switch levels. The microcontroller functions may be software programmed.

Referring now to Figure 2, the display 5 is formed from three lines of LEDs arranged in a triangle. The LEDs may be red in colour with the display resembling a "Hazard Warning TriangleO.

Microcontroller 3 emits signals to the display through the driver 4 representative of the degree of deceleration of the vehicle as defined by nine levels. If the vehicle decelerates very lightly and the microcontroller emits a signal representative of the first level of deceleration, lights 1 only of the display will be lit. If the vehicle decelerates a little more severely and the microcontroller emits a signal representative of the second level of deceleration, lights 1 and 2 of the display will be lit. This continues up until the eighth level of deceleration at which point all lights 1 to 8 will be lit. Thus the number of lights in the array illuminated at any one time is indicative of the rate of deceleration of the vehicle.

The most severe, ninth level of deceleration will make all the lights flash as provided by the "flash routine" in the microcontroller 3.

Thus if the vehicle decelerates, for example because the driver releases the accelerator pedal, the display will not be lit. The vehicle brake circuit could provide the power for the display through connection 6A to perform this function. Power for the circuit other than the display may be provided by the vehicle battery. Alternatively, the circuit including the display could be powered by the vehicle battery in which case the brake circuit could be connected to the input port 6B of the microcontroller which would sense when the brake was being operated, thus allowing the display to be illuminated. The visual display means may alternatively be powered by internal batteries.

A latch output and countdown time delay is also provided by the microcontroller so that when one level of deceleration is sensed and the appropriate LEDs are lit by the Latch output, the microcontroller will, if the next signal represents a lower level of deceleration, begin a count down time delay which keeps the LEDs lit for a predetermined period of time.

In use of the invention, the driver of a vehicle following the vehicle with the warning system will be able to judge how quickly the vehicle in front is decelerating (as provided by the number of lights illuminated) in addition to knowing that the vehicle in front is braking because of its brake lights. If the vehicle in front should do an emergency stop the ninth level of deceleration will be sensed and all the lights will flash as a warning. The flash routine, in this embodiment, is a set rapid frequency for a minimum set time following an emergency stop or crash.

The invention could take a different form to that specifically described. For example the control system could provide a signal of less or more than nine levels of deceleration. The visual display means could be other than a triangular array of LEDs, e.g a single line of LEDs or other lights and the number lit at any one time would be dependent on the level of deceleration. The sequence of light lit could also vary from that shown in Figure 2.

A modified display means is illustrated in Figure 3 and consists of a linear array of sixteen groups of LEDs, each group consisting of four LEDs. The display could extend across the vehicle, for example between the standard brake lights. The Figure also shows the lighting pattern for eight levels of deceleration.

The system could be designed so that the lights could "cascade" when turning off and/or on. Thus if the vehicle decelerates and the microcontroller emits a signal representative of the third level of deceleration, light 1, then lights I and 2, and then lights 1,2 and 3 will be lit.

In addition or alternatively when the vehicle stops decelerating, the lights 3 will first go out, then lights 2, and then lights 1. This "cascading" could make the display means more appealing and readable. In a modified triangle display two lights 1 are provided on each side of the display.

In addition, the display means may also be used if a vehicle is broken down or crashed. For example the lights could be designed to flash continuously at a frequency similar to that of standard vehicle hazard lights, thus forming a flashing hazard warning sign. This warning sign could be used instead of hazard warning lights with the advantage of a lower power consumption.

By way of example, the nine levels may be set by the gain network and lookup table as shown in the following chart:

Level of Deceleration Light Turned on Comment measured in g1s, 1. <25mg Brake covering 2. 55mg 1,2 3 85mg 1,2,3 4 115mg 1,2,3,4 Moderate Braking 140mg 1,2,3,4,5 6 170mg 1,2,3,4,5,6 7 200mg 1,2,3,4,5,6,7 8 230mg 1,2,3,4,5,6,7,8 Hard Braking 9 >400mg All lights flash Emergency Stop The flash routine may an "add-on" to a standard LED CHMSL (Light Emitting Diode - Centre High Mount Stop Lamp) as illiustrated in Figure 4. Typically only one level is required, therefore a linear acceleration switch may be used as the deceleration sensor. The level of deceleration to trigger this sensor may be >300mg. The control circuit of Figure 4 would typically be connected between the brake circuit 25 and a LED CHMSL 24, and may be made from standard circuit components.

When the brake is applied under normal conditions the display driver circuit 23 allows current to flow from the brake circuit 25 to the LED CHMSL 24. With the brake applied and the linear accelerometer switch 21 triggered, a flash routine 22 is activated to cause the display driver circuit 23 to interrupt current flow for brief intervals resulting in the LED CHMSL 24 flashing. The flash routine 22 is typically a monostable setting the routine time and an astable providing a high frequency. 10 An additional connection 26 (battery/accessory/ignition feed) may be added to provide power if the brake is not applied e.g. during an unexpected crash impact, or when the brake application time is shorter than the routine time. 15 The invention may have other uses other than with vehicles, and hence the term vehicle may be interpreted broadly to include any mass which is moving.

Further modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

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Claims

1. A vehicle warning system comprising an accelerometer, a control system connected to the accelerometer to provide a signal indicative for each of at least two levels of deceleration, and visual display means driven by the control system to display images representing any one of said two or more levels of deceleration.

2. A system as claimed in claim 1, in which the control system is a microcontroller.

3. A system as claimed in claim 2, in which at least one of said control system signals causes the visual display means to flash.

4. A system as claimed in claim 2 or claim 3, in which the microcontroller provides nine signals indicative of nine levels of deceleration.

5. A system as claimed in any preceding claim in which the visual display means is in the form of an array of lights.

6. A system as claimed in claim 5, in which the number of lights in the array illuminated is indicative of the rate of deceleration of the vehicle.

7. A system as claimed in any preceding claim, in which the visual display means is further controlled by the brake system of the vehicle whereby the visual display means can operate only when the brake pedal is operated.

8. A system as claimed in any preceding claim, in which the accelerometer is connected to the control system through an electronic filter whereby the visual display means is not greatly affected by the condition of a surface the vehicle is travelling on.

9. A system as claimed in any preceding claim, in which the accelerometer is connected to the control system through a gain control to adjust the levels of deceleration at which said signals are generated.

10. A vehicle warning system substantially as hereinbefore described with reference to and as shown in the accompanying drawings.