An automotive lamp flasher provides a visibly irregular series of flashes to indicate the existence of a distress situation. The flasher also provides a regular series of flashes as is done by existing flashers. Circuitry is provided to generate a nonuniform pulse train and repeatedly apply this pulse train to a lamp activation circuit. Broadly, a multiplexer with a plurality of input terminals is used, each having a logic level thereon. The multiplexer is sequentially stepped to provide an output representative of the sequence of logic levels on the input terminals. Preferred stepping means includes a timer for supplying a continuous sequence of uniformly spaced pulses, and a scaler responsive to these pulses for supplying a sequence of binary codes to the multiplexer.

BACKGROUND OF THE INVENTION 
Modern automobiles are invariably equipped with a so-called "emergency 
flasher" which, when activated by the driver, simultaneously activates 
flashing lights on all four corners of the vehicle. These lights are often 
the same lights that are also used as turn signals. While these four-way 
flashers may have originally been intended to provide indications of an 
emergency situation, increased and often indiscriminate use by the driving 
public has degraded the impact of these emergency flashers so that they 
provide no more than an indication that the vehicle is stopped, and is 
likely to remain so for more than an instant. Thus the emergency flasher 
does provide a very useful safety feature in that it tends to protect 
stopped cars from being hit by moving cars. However, there still exists 
the need for a device whereby a driver can signify to other drivers that a 
distress situation exists and that he needs help. 
A common way of indicating that help is needed is to erect a flag, 
typically on the radio antenna. Since many newer cars have radio antennae 
built into the windshield glass, and since many automobiles do not have 
radios at all, it is also a practice to tie a handkerchief to the door 
handle. 
The use of a flag-like indicator is not without its problems. The driver 
must get out of the automobile to place the flag in a visible position. 
This may be dangerous to the driver, may be undesirable due to bad 
weather, and may even be impossible, as for example, if the driver has 
become incapacitated. Moreover, a flag may not be visible in bad weather, 
especially at night. 
Another way of signalling to passing motorists that a distress situation 
exists is the placement of verbal signs on the rear ledge of the 
automobile so that they can be seen through the rear window. However, such 
signs tend to become lost or damaged so that they are not available when 
need for their use arises. Also, snow, dirt, window fog, or glare can 
prevent the sign from being visible. In addition, an incapacitated driver 
may be physically incapable of reaching over to the back ledge to place 
the sign in position. 
U.S. Pat. No. 3,226,707 to Newman et al. discloses a device which overcomes 
some of these difficulties. Basically, it is a permanently mounted fixture 
with a variety of internally stored signs, any one of which can be placed 
in a position for viewing. While such a device provides for relatively 
easy actuation by a disabled driver, it still relies on visibility through 
the rear window. Moreover, a permanent fixture for signs may be unsightly, 
can interfere with driver visibility out of the rear window, and is likely 
to be relatively expensive. 
SUMMARY OF THE INVENTION 
The present invention is an automotive device for providing an indication 
to other motorists that aid is required. The device is easily actuable, 
provides an indication which is highly visible while having no external 
manifestation when not in use, and can be adapted to existing wiring in 
the car without substantial modification. Broadly, the invention is an 
improved four-way flasher which is capable of providing a visibly 
irregular sequence of flashes, to indicate the existence of a distress 
situation. The invention also has the capability of providing a regular 
sequence of flashes as is done by existing flashers. 
The improved flasher contains circuitry for providing a pulse train wherein 
the pulses have non-uniform spacing and duration, and for repeatedly 
applying this pulse train to a lamp activation circuit. Broadly, a 
multiplexer with a plurality of input terminals is used, each having a 
logic level thereon. The multiplexer is sequentially stepped to provide an 
output representative of the sequence of logic levels on the input 
terminals. Preferred stepping means includes a timer for supplying a 
continuous sequence of uniformly spaced pulses, and a scaler responsive to 
these pulses for supplying a sequence of binary codes to the multiplexer. 
According to one aspect of the invention, the circuitry is packaged so as 
to be plug compatible with existing automotive flasher wiring sockets. 
This is preferably in the form of a small box having two or three prongs, 
depending on the socket. Thus the improved flasher can be easily 
substituted for the existing flasher in an automobile. A selector switch, 
preferably mounted within easy reach of the driver allows selection of 
either a uniform or a non-uniform pulse train. In the two-prong version, a 
ground connection for the circuitry may be taken from the switch.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Turning to the drawings, FIG. 1 sets forth the basic functioning of the 
present invention. Broadly, a plurality of lamps on an automobile is 
caused to flash on and off in a fashion representative of one of two 
electrical pulse trains. The first pulse train is uniform, i.e., the 
pulses are equally spaced and of equal duration. The second pulse train is 
non-uniform in that either the spacing or duration of the pulses varies 
from pulse to pulse. Reference timer 4 provides a uniform sequence of 
pulses to pulse train generator 6. Non-uniform pulse sequence selector 8 
defines the sequence of non-uniform pulses. Pulse train generator 6 
supplies a uniform pulse train on line 10, and a non-uniform pulse train 
on line 12. Pulse train selector 14, which preferably includes manually 
actuatable means transmits a pulse sequence representative of the selected 
pulse train to amplifier/activator 16, thereby activating lamps 18. Thus, 
the uniform pulse train results in a regular flashing sequence, as is 
provided by existing automobile flashers. The non-uniform pulse train 
causes an irregular sequence of light flashes which is used to signify a 
distress situation. 
FIGS. 2A and 2B show preferred embodiments of circuitry for realizing the 
functions set forth in FIG. 1. Solid state integrated circuit elements (to 
be described below) are used. Each of these elements has a configuration 
of pins that is industry-standard, and references to pin numbers refer to 
the standard configuration for the element in question. 
Referring to FIG. 2A, reference timer 4 of FIG. 1 preferably comprises a 
type 555 timer 20 such as that manufactured by Fairchild Camera and 
Instument Corporation, Mountain View, Cal., 94042 (herein after 
Fairchild), 20K resistor 22 is connected between pins 7 and 8, 1K resistor 
24 between pins 6 and 7, and 22 microfarad capacitor 26 between pin 6 and 
ground. Pin 8 is connected to a 5-volt power supply (as described below), 
and pin 1 is grounded. Pin 2 is shorted to pin 6, and pin 4 is shorted to 
pin 8. Pin 3 is connected to line 30. 
Pulse train generator 6 and non-uniform pulse sequence selector 8, both of 
FIG. 1 together comprise scaler 32 and multiplexer 34. Scaler 32 may be a 
type 7493 4-bit binary counter manufactured by Fairchild. Pin 5 of Scaler 
32 is connected to the 5-volt power supply and pin 10 is grounded. Pins 1 
and 12 are shorted, and pins 2 and 3 are shorted and tied to ground. Line 
30 is input to pin 14 on counter 32. Pins 12, 9, 8, and 11 are connected 
to 4-bit data line 36 which comprises individual lines 38, 39, 40 and 41. 
Pin 12 of Scaler 32 is also connected to output line 48. 
Multiplexer 34 may be a type 74150 manufactured by Fairchild. Pin 24 of 
multiplexer 24 is connected to the 5-volt power supply and pin 12 is 
grounded. Pin 9 is grounded. Lines 38-41 are input to pins 15, 14, 13 and 
11 of multiplexer 34. Pin 10 of multiplexer 34 is connected to output line 
50. 
Multiplexer 34 has 16 input data lines 60-75, connected to pins 1-8 and 
16-23 respectively. Each line may be supplied with a low logic level by 
being shorted to ground, or may be supplied with a high logic level by 
being left open or tied to the supply voltage through a large value 
resistor. The choice of which of data lines 60-75 to provide with a low or 
high logic level is dictated by the desired irregular sequence of pulses 
as will be more fully described below. 
Pulse train selector 14 of FIG. 1 preferably comprises a selector switch 80 
having a pole 88 and contacts 90 and 92, and three nand gates 82, 84, and 
86. Selector switch 80 is preferably a single pole-double-throw slide or 
toggle switch having pole 88 grounded and contacts 90 and 92 connected to 
lines 94 and 95 respectively. Lines 94 and 95 are connected to the 5-volt 
supply through 22K resistors 96 and 97 respectively. 
Gates 82, 84 and 86 are preferably part of a type 7400 quad two input nand 
gate chip manufactured by Fairchild. Only 3 of the 4 nand gates of the 
chip are used. Lines 50 and 94 are input to nand gate 82 (connected to 
pins 1 and 2). Lines 48 and 95 are input to nand gate 84 (connected to 
pins 4 and 5). Pins 3 and 6 corresponding to the output from nand gates 82 
and 84 respectively are connected to lines 98 and 100 respectively. Lines 
98 and 100 are inputs to nand gate 86 (connected to pins 9 and 10). Pin 8, 
the output of nand gate 86 is connected to line 110. 
Amplifier/activator 16 of FIG. 1 preferably comprises a transistor 120, a 
relay 124, a damper diode 126, and a 1K resistor 128. Transistor 120 has 
its emitter grounded, and its base connected to line 110 through 1K 
resistor 128. The collector of transistor 120 is connected through the 
activation coil of relay 124 to the positive terminal of the automobile 
battery 120. Damper diode 126 connected across relay 124 in the collector 
circuit is back biased and protects the transistor from excess voltage 
build up which may occur when transistor 120 is turned off and the coil 
field of relay 124 collapses. 
Transistor 120 may be a type 2N2222 NPN transistor. Diode 126 may be type 
1N4001. Relay 124 is a 12 volt relay having a resistance in its activation 
coil in the range of 1.2K. Relay 124 has a pole 130 and contacts 132 and 
134. Contact 132 is left open, and contact 134 is connected to the 
positive terminal of the battery. Pole 130 engages contact 132 when relay 
124 is not activated, and engages contact 134 when relay 124 is activated. 
Pole 130 of relay 124 is connected to line 136. 
The entire circuit gets its power from the automobile battery. The 
integrated circuit elements typically require a stabalized 5-volt power 
supply. Since the car battery provides a voltage (6-volt or 12-volt) that 
is above this value and is furthermore subject to fluctuation, the circuit 
must also contain its own 5-volt power supply. A 5 volt zener diode 142 is 
therefore used which has its anode grounded. A 47 ohm resistor 114 is 
connected between its cathode and the positive battery terminal. The 
resulting 5-volt level, suitable for supplying the integrated circuit 
components is taken off the cathode of zener diode 142 on line 146. 
The circuit as described above is preferably packaged as shown in FIG. 3. 
The circuit elements, shown schematically in phantom, are mounted to a 
small circuit board 150 which is housed in a box 152. Box 152 is 
preferably molded from an insulating material such as plastic, and has a 
cover 154 which may be bolted or otherwise fastened in place. Existing 
automotive flasher modules are of either a 2 or 3 prong design. The first 
prong is connected to the positive battery terminal, and the second is 
connected to one terminal of the lamps to be activated (the second 
terminal of the lamp to be activated being connected to ground). The third 
terminal (if any) is grounded. The operation of the flasher is such that 
the second terminal is repetitively shorted to the first, thereby 
energizing it with the battery voltage. In between, the second terminal is 
an open circuit. The above-described packaging of the present invention is 
designed to allow the present invention to be used in existing automobiles 
to replace existing flasher modules. FIG. 3 illustrates a 3-pronged device 
having metal prongs 156, 157, and 158, which are adapted to the standard 
automobile wiring sockets. Although the configuration of prongs may vary 
from one automobile manufacturer to another, it may be assumed for 
illustration purposes that prong 156 communicates to the automobile 
battery's positive terminal, that prong 157 communicates to the vehicle 
ground (the battery's negative terminal) and that prong 158 communicates 
to the lamps to be flashed. Prongs 156, 157, and 158 communicate to the 
circuit board and the elements thereon by wires 160, 161 and 162 
respectively. Selector switch 80, and more particularly contacts 90 and 92 
thereof are connected to the circuit by a multiple conductor 164 (which 
includes lines 94 and 96, of sufficient length that switch 80 can be 
mounted at a position where it is readily acceptable to the driver of the 
vehicle. Thus the switch might be mounted near the existing flasher 
actuation switch.) 
Referring to FIGS. 2A and 3, it can be seen that the circuit elements 
within dashed rectangle 180 of FIG. 2A correspond to those circuit 
elements on circuit board 150 that fit within box 152. The 3 prongs 156, 
157, and 158 in both figures correspond to the same items. 
FIG. 2B shows circuitry for use in a 2 prong installation. The circuitry is 
the same as that in FIG. 2A, except that prong 157 of FIG. 2A which 
communicates ground to the internal circuit elements is not present. 
Rather, ground for the circuit is supplied from pole 88 of switch 80, 
which is grounded by its mechanical connection to the automobile. Thus, it 
is necessary for an extra lead between switch 80 and the circuit elements 
within dashed rectangle 180'. Extra wire 182 leads from grounded pole to 
the circuits. 
Having thus described the circuitry, the operation can be understood. Timer 
20 provides a uniform sequence of pulses at pin 3 which are output on line 
30. The repetition rate is determined by the voltage divider comprising 
20K resistor 22 and 1K resistor 24. Resistor 22 may be varied to achieve a 
pulse repetition rate in the range of 2-4 pulses per second, which is 
twice the standard flasher frequency (typically required to be in the 
range of 1-2 pulses per second). Counter 32 counts the pulses on line 30, 
and generates a binary code on lines 38-41, according to the number of 
pulses that have come in on line 30. In the preferred embodiment, counter 
32 is a 4-bit counter having four output lines corresponding to 16 binary 
states. The outputs on individual lines 38, 39, 40, and 41 are uniform 
pulse trains with frequencies that are divisions of the frequency of 
pulses on line 30, the reduction being by factors of 2, 4, 8, and 16, 
respectively. Also each of these four pulse trains has its pulse duration 
equal to the interval between pulses. Thus, the output on line 48 (the 
same as the output on line 38) is suitable for driving lamps at the 
standard flasher frequency. It is the nature of the operation of binary 
counter 32 that the sequence of binary codes generated on four-bit line 36 
repeats itself after 16 pulses have come in on line 30. 
The binary code on lines 38-41 is fed to multiplexer 34. Depending on the 
binary code input to multiplexer 34, the logic level on the corresponding 
data line 60-75 will appear, inverted, on multiplexer output line 50. 
Thus, the sequence of pulses on line 50 is representative of the sequence 
of data line levels. Since the sequence of binary code on 4-bit line 36 
recycles every 16 pulses from timer 20, a sequence of 16 logic levels is 
provided, that sequence repeating itself every 16 pulses from timer 20. 
While it would be possible to set the logic levels on lines 60-75 in any 
one of a number of ways without departing from the spirit of this 
invention, two preferred sequences are set forth in the following table, 
referenced below as Table 1. 
______________________________________ 
(logic level) 
(multiplexer line) 
(0 = low, 1 = high) 
______________________________________ 
60 0 1 
61 1 1 
62 0 0 
63 1 1 
64 1 0 
65 1 0 
66 0 1 
67 0 0 
68 0 1 
69 1 1 
70 1 0 
71 0 1 
72 1 0 
73 0 0 
74 1 1 
75 1 0 
______________________________________ 
FIGS. 2A and 2B illustrate the connections for the first and second 
sequences respectively. 
Selector switch 80 determines which pulse sequence, the regular one on line 
48, or the non-uniform one on line 50, is output on line 110. When pole 88 
is connected to contact 90, thereby putting a low level on line 94, the 
output from nand gate 82 on line 98 is constantly high. At the same time, 
given the high level on line 95 to nand gate 84, the output on line 100 is 
the inverse of the pulse train on line 48. Given the condition on lines 98 
and 100, the output on line 110 is the inverse of the pulse train on line 
100, or equivalently, it follows the pulse train on line 48. Similarly, if 
selector switch 80 is set with pole 88 contacting contact 92, the output 
on line 110 is the pulse train on line 50. Thus, the selector switch and 
the nand gates serve to put one of the pulse trains on line 110. 
The pulse train on line 110 turns transistor 120 on in a corresponding 
fashion, thereby energizing relay 124 accordingly. Thus, terminal 158 is 
connected to the battery voltage in a fashion corresponding to the pulse 
train on line 110. It should be noted, that since the multiplexer output 
on line 60 is inverted with respect to the logic levels on lines 60-75, 
the sequence of flashes is complimentary to the sequence of logic levels 
on lines 60-75. 
Referring to Table 1, it can be seen that the first sequence of levels 
gives rise to a pattern of flashes that is basically a long flash (levels 
on lines 66-68) with four short flashes occurring before the next long 
flash. The second sequence results in a repetitive series of 
short-long-short flashes.