GB2344003A

GB2344003A - Vehicle braking warning system

Info

Publication number: GB2344003A
Application number: GB9825626A
Authority: GB
Inventors: Grant Alexander Thomson
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-11-23
Filing date: 1998-11-23
Publication date: 2000-05-24
Also published as: GB9825626D0

Abstract

A vehicle braking system is coupled to a transducer 15 which gives an output dependent on the extent of braking, this output being processed by comparators 17 to 23 which activate brake warning lights 1 to 14 in a display (Fig.3), so that as the braking level increases the number of activated warning lights in the display increases, giving the impression of a warning bar whose size increases with increasing braking. The signal from the transducer 15 is processed effectively to dampen fluctuations in the transducer output at low levels of braking, thereby dampening fluctuations in the display output at low braking levels, which might otherwise detract from the concentration of other drivers. The dampening is reduced at higher levels of braking, allowing rapid changes in braking to be indicated to other drivers. Inclusion of a capacitor 32 introduces hysteresis giving the required dampening characteristics.

Description

Brake Lights This invention relates to a brake warning system of the type that determines the extent of braking in a vehicle and displays this information to other drivers via a warning light whose illumination reflects the extent of braking.

Current brake warning systems rely on a binary system of ON or OFF to denote a driver's intention to slow down. This information is passed onto another driver by illuminating a red brake light at the rear of a vehicle. The decision to brake violently or to slow down gently is displayed in precisely the same manner. The objective of this invention is to provide a means for quantifying the braking intentions of a driver and displaying this information unambiguously to other drivers. Continuous fluctuations in braking results in a continuously varying warning display and is undesirable. This invention includes a system of signal processing to remove unnecessary fluctuations at low braking levels, but to allow for rapid changes in braking at high braking levels.

According to the present invention there is provided a brake warning system comprising a transducer to generate an analogue signal proportional to the extent of braking, a system for processing the brake transducer output, and a display unit to display the output of the processor to other drivers. Signal processing of the brake transducer output amounts to analogue to digital signal conversion and the addition of hysteresis to the signal such that variations in braking appears to be dampened heavily at low braking, yet not so dampened at high braking.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a block representation of the complete system.

Figure 2 shows the circuit representation of the complete system.

Figure 3 illustrates the brake warning light display unit.

Referring to the drawing, the system comprises an input transducer 15, for example an accelerometer or a potentiometer connected to the brake system in such a way that a large signal is produced under high braking. A buffer 16 then amplifies this signal. The amplifier output is then processed by a flash analogue to digital converter. The flash converter consists of an array of comparators 17-23, whose individual outputs controls the activation of individual lighting elements 1-14 in the brake warning light display unit using transistors 24-30. The reference signal to each subsequent comparator is decreased via a series of resistors. The number of bits in the analogue to digital converter, determined by the number of comparator circuits, determines the number of braking level steps. The comparator output is high when the sampled signal exceeds the reference signal. The lighting circuits are connected to a capacitor 32 in parallel. This introduces the necessary hysteresis to the display unit. The lighting elements, although shown as individual light emitting diodes, may consist of arrays of light emitting diodes or indeed any light source.

The lighting elements are arranged as shown in figure 3. An increase in braking is displayed as an increase in the number of lighting elements activated, giving the impression of a warning bar whose size increases.

Claims

Claims 1 A brake warning system comprising a transducer, a signal processing circuit, and a display unit to display the extent of braking unambiguously to other drivers.
2 A transducer, as claimed in claim 1, wherein the extent of braking in a vehicle is translated into an analogue signal.
3 A signal processing unit, as claimed in claim 1, wherein the analogue output of the brake transducer, as claimed in claim 2, is converted to x digital channels.
4 A signal processing unit, as claimed in claim 1 and claim 3, wherein the signal is processed to dampen fluctuations in the transducer output at low levels of braking, which might otherwise detract from the concentration of other drivers.
5 A signal processing unit, as claimed in claim 1, claim 3 and claim 4, wherein the damping applied to fluctuations in the transducer output is reduced at higher levels of braking, allowing rapid changes in braking circumstances to be communicated to other drivers.
6 A display unit, as claimed in claim 1, which consists of a bank of lighting elements whose illumination depends upon the digital output of the signal processor, as claimed in claim 1,3,4 and claim 5.
7 A display unit, as claimed in claim 1, wherein each individual digital output channel of the x-bit analogue to digital converter, as claimed in claim 3, is used to control the illumination of a lighting element.
8 A lighting element, as claimed in claim 7, wherein the definition of element corresponds to a single or a group of lighting devices which would all be illuminated according to the output of a particular digital channel, as claimed in claim 3.
9 The arrangement of the lighting elements, as claimed in claim 4, wherein an increase in braking corresponds to an increase in the number of activated lighting elements and causes an increase in the apparent dimensions of illuminated area in the display unit, as claimed in claim 4.
10 A brake warning system substantially as described herein with reference to Figures 1,2 and 3 of the accompanying drawings.