Vehicle signalling apparatus

This device for giving and controlling a vehicle U-turn signal comprises a U-turn signal indicator (1) and a control circuit. The U-turn signal indicator (1) can consist of an array of LEDs which makes a loop circuit with an arrow. One can be mounted on the front plate (2) of a vehicle, and another one can be mounted on the back plate. The control circuit consists of a rectifier, a first integrator, a second integrator, a counter, a switching transistor, and a relay. The output of the rectifier is connected to the inputs of the first and second integrators of which the outputs are connected to the CLK and to the RST of the counter respectively. The outputs of the counter and the rectifier are connected to the inputs of the NAND which controls the on or off working state of the switching transistor and the relay, to activate the U-turn indicator. The input of the rectifier is connected to the turn signal pulses of a vehicle. When certain pulse patterns are generated, the U-turn signal indicator is activated.

This invention relates to apparatus for giving and controlling vehicle 
signals, such as vehicle U-turn signals. 
Most vehicles are equipped generally with turn signals commonly referred to 
as left and right turn indicators. Using such turn signals to indicate the 
intention of a driver to make a U-turn is inconvenient in operation and 
ambiguous in meaning, which can result in an increase in the frequency of 
accidents. 
The invention seeks to mitigate problems such as this. 
According to the invention there is provided a vehicle signalling system 
comprising a main indicator, an activating device, a timing device for 
measuring the intervals during which the activating device is not 
activated and means responsive to the activating device and to the timing 
device to activate the main indicator when the measured interval is less 
than a threshold value. 
With fewer parts, eliminating extra switches, brackets, and redundant 
activation operations, apparatus embodying the invention can use the 
on-off-on wording state of an existing turn signal as the input. 
The U-turn indicator may comprise an array of LEDs which makes a loop 
circuit with an arrow.

In this embodiment the turn display comprises a plurality of LEDs 1, 
activated by a battery B1 through normally open contacts for a relay. The 
relay coil is activated by a battery B2 through a switching transistor 
8550. 
The vehicle has a turn indicator control (not shown) which causes a train 
of pulses to be supplied through a rectifier consisting of diodes D1 and 
D2 in series and a resistor RS return to earth. The pulse train is applied 
through respective diodes D4 and D5 to integrators I1 (C1 R1) and I2 (C2 
R2), the time constant of I1 being less than that of I2. The output of I1 
is applied through two inverters N2 and N3 in series to the clock input of 
a counter UL; the output of the integrator I2 is applied through a single 
inverter N1 to the reset input of the counter UL. The counter has outputs 
Q1, Q2, Q3 etc., and the outputs Q2 and Q3 are applied to respective 
inputs of a NOR gate through an inverter N4 to one input of a NAND. The 
rectified pulse train is applied directly to the other input of the NAND, 
whose output is connected to the base of switching transistor 8550 through 
a resister R4. 
The effect of this circuit is that the NAND gates the rectified pulse train 
being applied to the switching transistor 8550 according to the state of 
the counter UL. FIG. 2 shows waveforms at different points in the circuit. 
Waveform (a) shows a first pulse train of two pulses followed by a short 
delay, less than 3 seconds, followed by a second pulse train of four 
pulses, followed by a long delay. When the pulse train starts, the 
rectified pulses charge up the integrators, whose outputs are then high. 
When the train stops, the outputs decay according to their time constants 
(waveforms (b) and (c)), so that after a first time the clock input will 
be changed from high to low (waveform (d)) and after a second longer time 
the reset input will be changed from low to high (waveform (e)) provided 
that no further pulse train has started. The outputs start to decay after 
the pulse train stops, so the integrators are measuring the time during 
which the twin indicator control is not activated. When a second pulse 
train starts the integrators will again charge up. 
Considering first the case where the second train starts after both 
integrator outputs have dropped to the level which causes their output 
inverter to change state, as shown at the right hand ends of the 
waveforms, the reset input of the counter will have been activated and so 
the counter will be at zero. The following pulse train generated when the 
turn indicator is activated again will therefore be treated in exactly the 
same way as the first pulse train. 
Considering now the case where the second pulse train starts after the 
first integrator has dropped to change the state of its inverter, but 
before the second integrator has changed the state of its inverters, as at 
the left hand end of the waveforms, the reset input of the counter will 
not have been activated (waveform (e) remains low) and the counter will 
retain its count of one. When the second train arrives, the charging up of 
the first integrator will cause the counter to increase its count to two 
and the consequent output on Q2 (waveform (f)) will activate the NOR gate 
and enable the NAND which is gating the rectified pulse train being 
applied to the switching transistor. The switching transistor and the 
relay are thus energised by the gated pulse train (waveform (g)) and the 
U-turn indicator activated. The indicator continues to be activated until 
the pulse train stops, and 3 seconds later the second integrator output 
decays sufficiently to reset the counter, thus disabling the NAND. If the 
turn indicator control is activated again before the 3 second elapses 
counter UL will advance its count to 3 and the NAND gate will remain 
enabled and the U-turn indicator will be re-activated. 
A further activation of the turn indicator control within 3 seconds will 
not keep the NAND gate enabled because there is no connection from the Q4 
output of the counter UL to the inverter N4. 
In this embodiment, the time constant of the second integrator is selected 
so that the waveform (e) goes high 3 seconds after the pulse train stops 
provided another train has not started. 3 seconds corresponds to the time 
between the end of the right hand pulse in waveform (a) and the rise of 
waveform (e). The time between the end of the first pulse train and the 
start of the second is less than 3 seconds and so waveform (e) continues 
to remain low. 
As a practical matter, the driver should wait at least 3 seconds after 
activating the U-turn indicator (by activating the turn indicator control 
twice in quick succession) before activating the turn indicator control 
again, in order to allow the U-turn indicator to be reset. 
The connection of Q2 and Q3 to respective inputs of NOR gate prevents noise 
from the turn signal triggering the U-turn indicator falsely, since such 
noise may cause the counter to advance its count by one other than as a 
result of the signals from the integrators I1 and I2. 
As shown in FIG. 3, a hollow rectangle array of LEDs 1 (the U-turn 
indicator) is placed in a transparent plastic loop set and mounted on the 
rear plate 2 of the vehicle. The sides of the rectangle embrace the 
licence plate. 
An arrow head 4 is incorporated pointing downward on the left hand side of 
the indicator. A similar indicator can be mounted on the front plate of 
the vehicle with its arrow head pointing downward on the right side. 
FIG. 4 illustrates another way by which a brake indicator 3 is combined 
with the U-turn indicator 1, both of them being mounted on the back inside 
window of a vehicle. In this case, the brake indicator 3 and the U-turn 
indicator 1 are in different flashing colours. For example, the brake 
indicator is in red, while the U-turn indicator is in amber-green. 
The LEDs of the U-turn indicator can all be energised together or further 
switching means can be incorporated so that groups of LFDs are energised 
sequentially with the pulses of the train. The groups can be of different 
colours, or at different locations such as the opposite sides of the 
display.