Note: Descriptions are shown in the official language in which they were submitted.
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WIRELE;SS TOW LIG~ITING SYSTEM
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sackground of the Invention
1. Field of the Invention
This invention relates to a temporary,
radio controlled lighting system for disabled
vehicles in tow and includes a pair of light assem-
blies that are releasably mounted on the trailing
end of the disabled vehicle and which are automati-
cally illuminated upon energization of turn signals
or brake lights of the towing vehicle.
2. Descrlption of the Prior Art
Tow trucks and other vehicles for towing
disabled vehicles are normally equipped with flash-
ing or beacon-type lights to provide a warning to
other vehicles in the roadway. These types of
lights are normally mounted above the cab of the tow
truck for improving visibility to others. Such
lights, however, do not normally duplicate the
signals provided by the tail lights of the tow truck
which indicate to the drivers of trailing vehicles
that the brakes of the tow truck are applied or that
the driver of the tow truck intends to effect a
turn.
Moreover, the towed vehicle often obscures
the rear lights of the tow truck particularly in
instances where the towed vehicle is of substantial
size. As such, it is preferable, and mandatory in
some jurisdictions, to provide lights on the trail-
ing end of the towed vehicle that are interconnected
with the brake signal circuitry and turn signal
circuitry of the towing vehicle.
In the past, commercial tow truck opera-
tors have provided auxiliary rear lights for the
vehicle in tow by permanently wiring an auxiliary
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1 lighting assembly into the turn signal and brake
signal circuits of the tow truck, utilizing among
other components a section of flexible wire of a
length sufficient to extend from the circuitry of
the tow truck to the expected location of the
auxiliary lighting which is mounted on the trailing
end of the towed vehicle. Unfortunately, it has
been found in practice that the length of wire often
becomes tangled, torn and sometimes severed in use,
especially when the tow truck is maneuvered around
turns. As a result, the operator is then faced with
the time and expense of replacing the wire in order
to put the lighting system back into service.
Summary of the Invention
In order to overcome the problems noted
hereinabove, I have devised a tow lighting system
that includes a radio transmitter carried by the tow
truck and operatively connectéd to the light cir-
cuitry of the tow truck, along with a pair of sepa-
rate, self-contained lighting assemblies which each
include a power source and receiver for receiving
coded radio frequency signals. Both of the lighting
assemblies include a magnetic base for detachably
mounting the assemblies on, for instance, the top of
the trunk of the towed vehicle, and one of the
lighting assemblies is designated as "right" and the
other designated as "left" in order to duplicate the
function provided by left and right signal lamps
respectively of the tow truck.
In accordance with a preferred embodiment
of my invention, each of the lighting assemblies
- includes a bulb enclosure as well as an enlarged
base which houses a number of magnets as well as a
rechargeable battery for powering the bulb and the
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1 radio signal receiver that is located within the
bulb enclosure. When not in use, the lighting
assemblies are removed from the towed vehicle and
placed within a recharging stand within the cab of
the tow truck in order to retain the batteries at a
fully charged sta~e in readiness for the next use.
Optionally, the recharging stand may also house the
transmitter that is connected by a length of wire to
a transmitting antenna mounted atop the roof of the
tow truck cab.
In other preferred forms of the invention,
a bulb of each lighting assembly has two filaments,
one of which functions as a turn signal or brake
signal and the other of which provides steady illu-
mination when desired to serve as a running light.
Each lighting assembly includes a photo transistor
to automatically energize the filament for the
running light when the respective housing is exposed
to darkness, and optionally a switch may be provided
to manually turn the running light on or off.
These and other objects of my invention
will become more apparent from a consideration of
the following detailed description of a preferred
embodiment of my invention, when the description is
taken in conjunction with the accompanying drawings.
Brief Description of the Drawings
Figure 1 is a perspective view o~ a tow
truck that is towing a disabled vehicle, wherein is
provided a wireless tow lighting system constructed
in accordance with the principles of my invention;
Fig. 2 is an enlarged, rear elevational
view of one of two lighting assemblies of the system
shown in Fig. 1, with a portion of a lens of the
assembly cut away to reveal an internal bulb;
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1 Fig. 3 is an enlarged, side cross-
sectional view of the lighting assembly shown in
Fig. 2, showing among other things a battery and
magnets which are received in a chamber of a base of
the assembly;
Fig. 4 is essentially an electrical
schematic diagram of a radio frequency transmitter
of the system depicted in Fig. 1; and
Fig. 5 is essentially an electrical
schematic diagram of a radio frequency receiver and
signal lamp circuitry of the system illustrated in
Fig. 1.
Detailed Description of the Drawings
Referring initially to Fig. l, a wireless
tow lighting system 10 includes, in broad terms, a
transmitter 12 that is carried by a towing vehicle
such as a tow truck 14, and a pair of signal re-
ceiving light assemblies 16, 18 that are releasably
mounted on a body 20 of a disabled vehicle 22. An
antenna 24 is mounted on the roof of the cab of the
; tow truck 14, and is interconnected by a wie (not
shown~ to the transmitte 14 which may optionally be
carried behind the seat within the passenger com-
partment.
Reference is now made to Figs. 2 and 3
wherein the lighting assembly 16 is shown in qreater
detail, although it is to be understood in this
regard that the light assembly 18 is substantially
similar to the assembly 16 with the specific excep-
tions enumerated below. The assembly 16 includes a
housing, broadly designated 26, that comprises a
~ somewhat rectangular base 28 and an enclosure 30
; coupled to the top of base 28.
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1 A dual filament bulb 32 (Fig. 2) is
mounted within the enclosure 30 and is covered by a
translucent lens 34 of a reddish tint. A photo
transistor 36 is mountetl at the top oE a peripheral,
cylindrical wall of the enclos~lre 30, and a three
position slide switch 38 is carried on the side of
the enclosure 30 with a finger engaging lever of the
switch 38 protruding through a complemental slot in
the wall of enclosure 30. ~ radio frequency signal
receiver 40, the position of which is indicated
generally in Fig. 2, is mounted within the enclosure
30 and is operatively coupled to a flexible, up-
standing antenna 42 that protrudes through the top
of the enclosure 30.
The base 28 of the housing 26 has struc-
ture defining an internal chamber 44 (Fig. 3) that
receives a source of power such as a rechargeable
six volt battery 46. In addition, the chamber 44
carries a pair of elongated, parallel, magnetic
mounting assembles 48 disposed on opposite sides of
the battery 46, and each assembly 48 includes a
central magnet 50 engaged on opposite sides by
metallic plates 52 that extend through slots formed
in the bottom of base 28. ~ach plate 52 is ver-
tically shiftable to a limited extent in order to
come into firm contact with the contour of a
selected portion oE the vehicle body 20.
~ jack 54 extending through a sidewall of
base 28 is provided for recharging the battery 46
whenever the lighting assembly 16 is not in use.
Conveniently, the transmitter 12 within the cab of
tow truck 14 is housed in a recharging stand that
has a reception area for each of the lighting
assemblies 16, 18 along with appropriate leads
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1 having plugs for connection with each recharging
jack 54 when the assemblies 16, 1~ are not in ser-
vice.
In addition, the base 2~ is marked with
external indicia 56 in the nature of a "~" or the
term "right" to indicate to the operator that the
assembly 16 is to be placed on the driver~s right
side of the trailing end of the disabled vehicle 22.
Likewise, although not shown in detail, the lighting
assembly 18 has a housing 26a tFig. 1) with external
indicia in the nature of a "L" or the term "left" to
indicate to the operator that the assembly 18 should
be placed on the side of the disabled vehicle 22
that corresponds to the driver's left side.
The transmitter 12 of the system lO is
shown in detailed schematic form in Fig. 4 and
includes three terminals designated Jl, J2 and J3
that are connected, respectively, to wires of the
tow truck 14 that are energiæed upon application of
the right turn signal, left turn signal and brakes.
The terminal Jl is connected to a current limiting
resistor R1 (770 ohms), the other side of which is
coupled to pin 1 of a transistor-transistor-logic
(TTL) integrated circuit 57 (74HC266) as well as the
cathode of a zener diode CR1 (IN749A), the other
side of the latter o which is connected to ground.
Terminal J2 is connected by a resistor R2 (770 ohm)
to pin 5 of the TTL circuit 57, as well as to the
cathode of zener diode CR2 (IN749A) that has an
anode coupled to ground. Terminal J3 is intercon-
nected by a resistor R3 (770 ohm) to pins 2 and 6 of
the TTL circuit 57, as well as the cathode of a
zener diode CR3 (IN749A), the anode of which is
grounded.
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l The TTL circuit 57 is powered by the power
supply of the towing vehicle or tow truck 14 and
includes two exclusive NOR gates. From the 12 volt
supply of the tow truck 14, current flows through a
~anual switch S1 to a resistor R4 (14.7 ohms) that
S is connected by a lead 58 to pin 14 of the TTL
circuit 57. The cathode of a zener diode CR4
(IN963B) is connected to lead 58, while the anode of
CR4 is grounded. Capacitors C1 (100 microfarad), C2
(10 microfarad) and C3 (0.1 microfarad) are also
interconnected between lead 58 and ground along with
a zener diode CR5 (IN749A), the anode of which is
connected to ground.
Pins 3 and 8 of the TTL logic circuit 57
are electrically coupled to pins 5 and 6 respec-
tively of a radio frequency encoder/transmitter U1
(LM1871). In addition, the lead interconnecting pin
3 of the TTL logic circuit 57 and pin S of U1 is
connected to the cathode of a zener diode CR6
(IN747A), the anode of which is grounded. The lead
~0 interconnecting pin 4 of the TTL circuit 57 and pin
6 of U1 is connected to the cathode of ~ener diode
CR7 ( IN747A) which also has an anode connected to
ground.
The encoder/transmitter U1 receives power
through pin 14 which is connected to lead 58, the
latter of which is coupled to a capacitor C4 (0.1
microfarads) which is coupled on its opposite side
to ground. In addition, pin 9 of Ul is connected to
ground. Pins 1, 2, 3, 16, 17 and 18 of U1 are
connected to a resistor R5 (82K ohm), the other side
of which is connected to pin 8 of U1 as well as one
side of another resistor R6 (56K ohms). The
remaining side of resistor R6 is electrically
coupled to pin 15 of U1. Pin 7 of U1 is connected
by a capacitor C5 (0.1 microfarad) to ground, and
also is coupled to one side of a resistor R7 (200K
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1 ohm), the other side of which is connected to lead
60. Lead 60, in turn, is connected to pin 4 of U1
as well as a capacitor C6 (0.1 microfarad), the
other side of which is grounded. A capacitor C7
(0.005 microfarad) interconnects pin a of Ul and
ground, while a capacitor C8 (62 picofarad) inter-
connects pin 10 of Ul and ground. Moreover, resis-
tor R8 (47K ohm) interconnects pin 10 of Ul and lead
60. One side of a capacitor C9 (0.01 microfarad) is
connected to pin 12 of U1, while the other side of
C9 is coupled to ground.
One side of a crystal Y1 (49.86 mHz) is
coupled to pin 10 of U1, while the other side of Yl
is electrically interconnected with one side of
capacitor C10 (47 picofarad) as well as one side of
capacitor C11 (220 picofarad). The remaining side
of C10 is connected to pin 11 of U1, while the
remaining side of C11 is coupled to a lead 62 that
is directly connected to pin 13 of U1. Lead 62 is
also connected to a capacitor C12 (1500 picofarad)
and a capacitor C13 (27 picofarad), and the other
side of capacitors C12 and C13-is grounded. Lead 62
is also coupled to one side of the primary winding
of transformer L1 (Toko KEN K4635 BJE), while the
other side of the primary winding of L1 is coupled
to pin 11 of U1.
Opposite sides of the secondary winding of
Ll are coupled to respective, opposite sides of a
capacitor C14 (33 picofarad), one side of which is
also connected to one end of a tuning coil L2
(Miller ~9330~10). The remaining side of L2 is
connected to the antenna 24 (see also Fig. 1) which
is mounted on the top of the cab above the tow truck
14. The antenna 24 is advantageously one to two
l feet in length and constructed of 0.023 inch
diameter flexib]e wire.
An electrical schematic for the receiver
40 is illustrated in Fig. 5 and is substantially
identical to the receiver of assembly 18. The re-
ceiver 40 includes a radio control receiver/decoder
U2 (LM1872) that receives power from the 6 volt re-
chargeable battery 46 that is shown in Fig. 3. ~n
on-off switch S2 interconnects pin 6 of U2 and the
six volt battery 46 in order to disable the receiver
40 when not in service.
One side of a capacitor C16 ~0.01 micro-
farad) is coupled to pin 6 of U2, while the other
side of capacitor C16 is connected to ground. Pin
- 18 of U2 is connected to pin 2 of a mixer trans-
former T2 (455 kHz; Toko 10 EZC type R~IC-202313 NO).
Resistor R10 (200 ohm) interconnects pin 3 of T2 and
one side of switch s2 adjacent pin 6 of U2, and pin
3 of T2 is also coupled to one side of a capacitor
C17 (0.01 microfarad), the other side of which is
grounded.
Pin 17 of receiver/decoder U2 is coupled
to pin 4 of T2 and also to one side of a capacitor
C18 (0.001 microfarad). I'he remaining side of
capacitor C18 is connected to pin 6 of T2 and also
to ground. Pin 16 of U2 is coupled to ground by
means of a capacitor Cl9 (0.1 microfarad).
n intermediate frequency transformer T3
(455 kHz Toko 10 EZC type RMC402503 NO) includes pin
2 which is coupled to pin 15 of U2. Pin 3 of T3 is
connected to one side of a capacitor C20 (0.01
microfarad), the remaining side of which is coupled
to ground.
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1 A resistor Rll (100K ohm) interconnects
pin 13 of U2 and one side of the switch S2 as shown
in the drawing. Pin 13 of U2 is also coupled to one
side of a capacitor C21 (0.05 microfarad) the oppo-
site side of which is grounded. ~s shown, pins 8,
10 and 14 of U2 are directly connected to ground.
A lead 66 is electrically coupled to one
side of switch S2 as well as to one side of a capa-
citor C22 (0.01 microfarad), the other side of which
is grounded. A capacitor C23 (24 picofarad) inter-
connects lead 66 and pin 1 of U2. A LO coil L3
(Toko 10K type KEN-9028 DZ 6T) is connected on one
side to lead 66 and on an opposite side to pin l of
U2 as well as one side of a parallel-mode crystal Y2
(49.~6 mHz), the other side of which is directly
coupled to pin 2 of U2.
Pin 3 of the receiver/decoder U2 is
directly connected to ground as well as one side of
; a capacitor C24 (0.1 microfarad). The remaining
side of capacitor C24 is connected to pin 4 of U2 as
well as to one terminal of an antenna input trans-
former T4 (Toko 10K type KEN-4028 DZ). Opposite
sides of another winding of T4 are connected to
opposed leads of a capacitor C2S (24 picofarad), and
one side of the capacitor C25 is also interconnected
with antenna 42 (see also Figs. 2 and 3) which may
advantageously be in the form of a whip antenna of
one to two feet in length.
One lead of the transformer T4 is also
connected to pin 5 of U2 which is in electrical
communication with the cathode of diode Dl (IN4454).
The anode of diode D1 is also connected to the
aforementioned lead of transformer T4 that is
coupled to pin 4 of U2.
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l Pins 7 and 9 of the decoder/receiver U2
are connected to corresponding poles of a single
pole double throw switch S3. The remaining, common
contact of switch S3 is connected to the base of a
PNP transistor Q1 (2N4920), the emitter of which is
powered by means of a lead in electrical communi-
cation with one side of switch S2. The collector of
transistor Ql is connected to one side of a filament
68 within bulb 32 (see also Fig. 2) while the
remaining side of filament 68 is coupled to a
grounded, conductive case of bulb 32.
R second filament 70 within bulb 32 is
grounded on one side by means of the aforementioned
metallic case, and the other side of filament 70 is
coupled to one side of a single pole single throw
switch S4, the other side of which i5 coupled to the
six volt battery 46 through switch S2. In addition,
the latter-mentioned side of filament 70 is con-
nected to one side of a normally on photo transistor
36 (see also Figs. 2 and 3), and the remaining side
of photo transistor 36 is connected to the recharge-
able battery 46 throuyh switch 52. The photo tran-
sistor 36 switches off in the presence of light.
Operation
Once the disabled vehicle 22 has been
connected to the tow truck 14 for towing, the light-
ing assemblies 16, 18 are removed from the recharg-
ing stand that also houses transmitter 12 once the
recharging leads (not shown) of the stand have been
disconnected from the jacks 54. The lighting assem-
blies 16, 18 are then placed on the trailing end of
the disabled vehicle 22, such as the top of a trunk
of vehicle 22, and positioned such that the lighting
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1 assembly 16 is disposed to the driver's right side
while the lightir~g asse~bly 18 is positioned to the
driver's left side. 'I'he magnets 50 shift within the
base 28 as may be necessary to accommodate the
surface contours of the body 20 of disabled vehicle
22.
Next, switch S1 of the transmitter 12 is
turned on to provide power to the TTL circuit 57 as
well as the encoder/transmitter U1. In addition,
switch S2 of each of the lighting assemblies 16, 18
is turned on to power the receiver/decoder U2 as
well as remaining components of the rèceiver 40.
If the system 10 is used at night and the
housing 26 of each assembly 16, 18 is thus exposed
to darkness, the photo transistor 36 enables current
to flow to the filament 70 to serve as running
lights. In this mode of operation, the photo tran-
sistor 36 interrupts the flow of current to the
filament 70 whenever sùfficient light is detected.
As an option, the operator may close switch S4 to
manually illuminate filament 70.
In this regard, switches 52 and S4 of the
receiver 40 may be incorporated into a single, three
position switch such as the switch 38 that is
depicted in Figs. 2 and 3. In this manner, the
central position of the switch 38 may be designated
as "off" for disabling power to all remaining com-
ponents of the receiver 40. In accordance with this
preferred construction, switch 38 when shifted to
one side is equivalent to closing of both switches
S2 and S4 ~and thus constant energization of fila-
ment 70), while shifting of the switch 38 to the
opposite extreme is equivalent to closing of only
switch S2 while leaving S4 open, so that automatic
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1 energization of the filament 70 is instead provided
by means of photo transistor 36.
Viewing Fig. 4, each exc:Lusive NOR gate of
the TTL circuit 57 is connected to the brake signal
circuitry of the tow truck 14, as well as to one of
S the turn signal circuits of the tow truck 1~.
Terminals J1, J2 and J3 along with TTL circuit 57
thus represent a means for sensing activation of the
turn signal circuitry or brake signal circuitry of
tow truck 14. The output of each NO~ yate is low
when one and only one input of the same gate is
high. Thus, if the brake signal and a turn signal
of the tow truck 14 are energized simultaneously,
the output of the NOR gate toggles back and forth
between a low and high state.
The encoder/transmitter U1 creates a pulse
; modulated FM signal at 49.86 mHz for every low
output received on pins 5 and 6 of U1. In the
particular embodiment described above, four pulses
are transmitted for a right turn, five pulses are
transmitted for a left turn and six pulses are
transmitted during application of the brakes.
The receiver 4~ receives from antenna 42
the 49.86 pulsed mHz signal and mixes the signal
do~n to an intermediate frequency of 455 kHz and
thereafter outputs a decoded signal relative to its
input. The receiver/decoder U2 thus represents a
means for receiving a wireless signal transmitted
from Ul and in response thereto for providing an
output signal indicative of the activation of the
turn signal circuitry or the brake signal circuitry
of tow truck 14.
Pins 7 and 9 of the receiver/decoder U2
represent signal outputs suitable for the left
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1 lighting assembly 18 and the right lighting assembly
16 respectively, the sélection of which is deter-
mined by the position of S3. Alternatively, switch
S3 may be eliminated and the gate of transistor Q1
connected directly to pin 7 of U2 for the receiver
40 of the lighting assembly 16 with pin 9 of U2
disconnected, while pin 9 of U2 is coupled to the
gate of Q1 for the receiver of lighting assembly 18
while pin 7 of V2 is disconnected. In this manner,
the indicia 56 serve to indicate the position of the
assemblies 16, 18 on the disabled vehicle 22 so that
the operator need not manually adjust a position
selector switch such as switch S3.
While the foregoing represents a detailed
description of the currently preferred embodiment oE
my invention, it is understood that those skilled in
the art may make various modifications or additions
to my invention without departing from the gist and
essence oE my contribution to the art. Accordingly,
the invention should be deemed limited only be a
fair scope of the claims which follow along with
their mechanical equivalents.
What I claim is:
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