Driver alerting device

An alarm device for a construction vehicle including a transceiver adapted for mounting at the rearward end of a vehicle for directing its wave output rearwardly of the vehicle. Return wave signals for many objects within the transceiver range are picked up and supplied to the transceiver by an antenna. Any resultant doppler shift signal is amplified for driving an audio alarm positioned on the vehicle. The circuit is adapted for electrical connection to the reverse gear of the vehicle for activation only when the vehicle transmission is engaged in reverse gear.

BACKGROUND OF THE INVENTION 
The present invention is directed generally to a device for alerting the 
driver of a rearwardly moving vehicle to the presence of any object in 
close range behind the vehicle. More particularly, the present invention 
is directed to a micro-wave radar device using the doppler shift principle 
to detect the presence of a moving target within the transceiver range. 
The federal government presently requires that construction equipment such 
as tractors, trucks, graders, dozers, etc. have a loud audio alarm mounted 
thereon which constantly sounds when the equipment is being moved in a 
rearwardly fashion. The audio alarm is incorporated or connected to the 
reverse gear of the transmission so that the alarm will immediately sound 
when the vehicle is placed in reverse gear. A problem associated with the 
constantly sounding alarm is that operators of the equipment are 
experiencing hearing damage due to the fact that the alarm must be loud 
enough so as to overcome the background noise. A further problem 
associated with the present alarm is that the alarms are activated for 
such long periods of time that persons working in the vicinity of the 
construction equipment become immune or inattentive to the alarm. 
It is therefore a principal object of the invention to provide an alarm 
device for construction equipment which is activated only when an object 
or person is behind the equipment and the equipment is about to be or is 
being moved rearwardly. 
A further object of the invention is to provide an improved device for 
alerting the driver of a rearwardly moving vehicle to the presence of a 
person or object within a short range distance behind the vehicle as well 
as alerting the person or object who is within the short range distance 
behind the vehicle. 
Finally, an object is to provide an alarm device for construction equipment 
which is economical of manufacture, simple and rugged in construction and 
efficient in operation. 
SUMMARY OF THE INVENTION 
The alarm device of the present invention includes a transceiver adapted 
for mounting at the rearward end of the construction equipment for 
directing its wave output rearwardly of the equipment. Return wave signals 
from any object within the short transceiver range behind the equipment 
are supplied to the transceiver through an antenna connection. Any 
resultant doppler shift signal is amplified for driving the audio alarm. 
The circuit of the device is activated only when the vehicle transmission 
is engaged in reverse gear. 
The alarm thus immediately sounds an alarm when any moving or stationary 
object is detected within the short transceiver range behind a rearwardly 
moving piece of equipment upon which it is installed. Even when the 
equipment is stationary, the device will signal the presence of any moving 
object within the transceiver range when the equipment is in reverse gear.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The alarm device of this invention is indicated generally at 10 in FIG. 1 
installed on the rear 12 of a piece of construction equipment 14. Device 
10 operates by micro-wave radar using the doppler shift principle to 
detect the presence of a moving target within the transceiver range. 
The operating elements of the device 10 are wholly electronic and are shown 
in FIG. 2 as including a transceiver 20, an antenna 22, an intermediate 
frequency amplifier 24 and an audio alarm 26. 
The transceiver 20 includes a gunn diode 28 mounted in a wave guide cavity 
which acts as the transmitter and local oscillator, together with a 
schottky barrier mixer diode 30 for the receiver. Electromagnetic 
radiation transmitted from the gunn diode 28 is reflected back at the 
antenna by any object within the transceiver range. If that object is 
moving relative to the vehicle, the frequency shift of the wave reflected 
by the moving object is measured electronically and triggers activation of 
the alarm 26. 
In the preferred embodiment, output frequency of the transceiver 20 is 
factory preset at 10.525 GIGA HERTZ. Power output is 5 milliwatts minimum. 
Operating voltage is 8 volts D.C. The resultant doppler frequency obtained 
is 31.39 HERTZ for each mile per hour of radio velocity. The transceiver 
is unaffected by the presence of magnetic fields, noise, light and varying 
weather conditions. 
Antenna 22 may be provided as either a high gain antenna or low gain 
antenna. The high gain antenna is preferred for application with 1/4 ton, 
1/2 ton and 1 ton vehicles measuring 80 inches maximum in width. The low 
gain antenna is preferred on 1 ton and larger vehicles measuring 80 inches 
and greater in width. The range of the antennas is adjustable and may be 
user set to accommodate virtually any vehicle. This adjustment is 
incorporated in the intermediate frequency amplifier 24 and is accessible 
from the outside of the unit. Antenna 22 is preferably constructed of 
machined aluminum and is also preferably flange-mounted directly to the 
transceiver 20, thus eliminating the effects of noise and spurious 
response. Lines 32 in FIG. 1 illustrate an example of a typically adjusted 
wave pattern. 
The intermediate frequency amplifier 24 is a solid state, multi-stage 
operational amplifier designed to amplify and shape the resultant doppler 
shift signal. The circuitry is card mounted and has built-in range and 
sensitivity controls. The amplifier is designed to interface with the 
existing reverse switch 34 (FIG. 2) in order to activate the circuit only 
during reverse operation of the equipment. Reverse switch 34 is typically 
associated with the transmission of the equipment in conventional fashion. 
The audio alarm 26 is mounted near the operator's station 16 so as to be 
readily audible to the driver of the equipment and readily audible to 
anyone positioned behind the equipment. Amplifier 24 drives both the audio 
alarm 26 and a light emitting diode mounted on the unit. The purpose of 
the light emitting diode is to aid in the adjustment of the unit in the 
event that the alarm is not audible to the one adjusting the unit. 
The transceiver 20 is shown in FIG. 3 as including a housing 36 which is 
diagonally sectioned to provide a pivotal top cover 38. The wave output 
from the transceiver 20 is transmitted outwardly through a rearwardly 
protruding channel section 40 on the rear wall of housing 36. A mounting 
flange 42 extends downwardly from the housing for ready attachment to a 
vehicle bumper or the like. 
The circuitry is card mounted and all components are treated with a 
conformal coating to prevent the effects of moisture and salt. Electrical 
hook-up to the vehicle is achieved via a splash-proof four circuit 
connector mounted on the side of the unit. One of the four leads may be 
connected to the ignition switch of the equipment, one to the back-up 
lights or reverse switch 34 on the transmission, one to ground 44 and one 
to the alarm 26. 
The audio alarm is preferably a solid state piezoelectric alarm capable of 
developing 80 decibels at 12 volts D.C. 
In operation, the transceiver 20 is activated to transmit electromagnetic 
radiation whenever the vehicle ignition is on and the transmission is 
engaged in reverse gear. This closes the vehicle reverse switch 34. A 
reducer may be provided between the transceiver 20 and reverse switch 34 
to adjust the operating voltage to 8 volts D.C. The transceiver range 
spans the width of the equipment 14 and extends rearwardly approximately 6 
to 12 feet. The maximum range would be approximately 20 feet. 
As the equipment is driven rearwardly, reflected signals from any object 
within the transceiver range, such as a person 46, are picked up by 
antenna 22 and supplied to the mixer diode 30 where the frequency shift is 
measured electronically. Amplifier 24 is designed to amplify and shape the 
resultant doppler shift signal and to activate the alarm 26. Note that 
when the vehicle is backing up, both stationary and moving objects within 
the transceiver range will be detected since there will be relative 
movement between the transceiver and these objects. Even when the vehicle 
is stationary, a moving object, such as a person, will be detected by the 
transceiver and result in activation of the alarm when the vehicle 
transmission is in reverse. A stationary object will not be detected when 
the vehicle is stationary since there is no relative movement to cause a 
doppler shift signal to be generated. Thus, the alarm will stop once the 
moving object leaves the transceiver range. Likewise, when the audio alarm 
is activated by a stationary object, it will stop once the vehicle is 
stopped. 
Thus it can be seen that a novel alarm device has been provided for 
construction equipment which is only activated when the transmission of 
the equipment has been placed in reverse and the device senses a moving 
object or when the equipment is being backed up and the sensor senses 
either a moving or stationary object within the transceiver range. 
Thus there has been shown and described an alarm device for construction 
equipment which accomplishes at least all of the stated objects.