Wireless control system for a travelling toy using a single transmitting and receiving channel

This invention is concerned with a remote control trans-receiver system in which a transmitter having a single channel is used for transmitting information to a remote receiver adapted to receive the information for controlling the movements of a toy vehicle. The single transmitting channel includes means to provide modulated information onto a carrier wave for controlling the forward, rightward and leftward movements of the toy vehicle, and a switching device for preventing the transmission to the receiver of any modulating information to permit stopping of the forward movement of the vehicle and to enable, when desired, reverse movement of the toy vehicle. The receiver detects the modulated information, when present, for effecting forward, rightward or leftward movement of the toy vehicle. The receiver further includes a switching device which responds to the absence of a modulating signal on the carrier to stop and then reverse the direction of travel of the toy vehicle.

BACKGROUND OF THE INVENTION 
This invention is concerned with a remote control system and more 
particularly with a transmitting unit distant and separate from a receiver 
unit, the latter being carried by a device; e.g. a toy vehicle for control 
thereof by the transmitting unit. The invention also relates to a method 
in which a single transmitting frequency serves under specified conditions 
to control diverse movements of the movable device. 
It is known from U.S. Pat. No. 3,720,281 to use high frequency carrier 
signals to control the movement of the rear wheels of a golf club carrier 
or golf cart. In the disclosed device, movement of the vehicle is under 
control of separate drive motors for the rear wheels as a function of 
signals received by a pair of antennae. The need for left and right 
antennae for this purpose complicates the system making it more costly and 
more likely to malfunction due to its increased complexity. 
It is also known to control machinery from a remote location, as 
exemplified by the disclosure of U.S. Pat. No. 3,454,927. In particular, a 
transmitter is provided which generates a fixed sequence of tone groups, 
one of which is a low frequency tone and the other of which is a high 
frequency tone. One tone is for function control while the other 
determines the operation to be carried out by the function selected. The 
tones of the different frequencies are separated at the receiver unit. To 
discriminate between tones of different frequencies, a multiple channel 
receiver must be used which again adds to the complexity and cost of the 
device, both undesirable factors since toys to be marketable must be of 
simple design and low cost construction. 
SUMMARY OF THE INVENTION 
In the present invention which is directed to the remote control for a 
movable toy device, a transmitter is provided which generates and 
transmits a single high frequency signal, e.g., a signal whose frequency 
is exemplified as being 27.125 MH.sub.z, to a remote receiver housed in a 
toy device. The receiver advantageously has a single receiving channel for 
controlling motor means which governs the front wheels of the toy device 
selectively to enable forward and reverse movements as well as stopping 
and turning of the toy device. The single high frequency signal is 
modulated in order to effect the forward and turning movements of the toy. 
Because only a single high frequency carrier need be generated and because 
the modulation of the carrier determines forward, left and right turn 
movements of the vehicle only a single receiving antenna need be used in 
conjunction with a single receiving channel which incorporates detector 
means for demodulating the received modulated carrier and band pass 
filters for passing the demodulated signal, as a function of the frequency 
of the demodulated signal, through a high pass and a low pass filter 
network, the relative outputs of which determine the direction of movement 
of the vehicle; e.g. when the outputs are equal the vehicle moves straight 
ahead and when unequal will turn as a function of the relative output 
levels, derived from the filter network, which when amplified energizes 
motors which turn the wheels of the vehicle. 
It will be appreciated from the foregoing that among the many objects of 
the invention, one is to provide a radio control device which utilizes 
single transmitting and receiving channels for controlling movement of the 
toy vehicle. 
Another object of the invention is to control movements of a toy vehicle as 
a function of a signal modulated on a single high frequency carrier, the 
frequency of the modulated signal determining the direction of movements 
of the vehicle. 
With the foregoing in mind, we provide in accordance with the invention a 
system comprising a transmitting unit selectively to transmit an 
unmodulated or a modulated carrier of a predetermined frequency and a 
receiver unit for receiving, by means of a single antenna, the modulated 
or unmodulated carrier signal transmitted by the transmitting unit. The 
received signal, after detection and amplification, is fed to a low-pass 
filter network and a high-pass filter network which branch off in parallel 
from an amplitude limiter. The low-pass and high-pass filter outputs after 
rectification and amplification, if necessary, control energization of, 
for example, DC motors which drive the wheels of the vehicle. 
For advancing, stopping and backing up of the toy, a switch provided in the 
transmitting unit is opened, whereby to transmit an unmodulated carrier 
signal which when received by the receiver operates, as hereinafter more 
fully described, a rotary relay or servo motor is actuated stepwise, to 
stop, reverse or advance the vehicle as schematically shown in FIG. 6. 
Other objects and advantages of the invention will become obvious after 
considering the detailed discussion of the invention in connection with 
the preferred embodiments thereof shown in the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now more particularly to FIG. 1 of the accompanying drawings, 
which shows the transmitter unit in accordance with the present invention, 
there is illustrated a remote control signal information transmitting unit 
which comprises a high frequency oscillator 10 which generates a carrier 
of high frequency for transmission by transmitting antenna 12. For 
modulating the carrier there is provided a low frequency generator 14 
which may take the form of a variable frequency multivibrator the 
frequency of which may be determined by positioning the variable arms of 
parallel connected resistors 18 under control of handle 20. Switch 16, 
located between multivibrator 14 and oscillator 10, when closed permits 
modulation of the carrier with the multivibrator output at the 
multivibrator frequency and when opened isolates the multivibrator output 
from the carrier signal so that an unmodulated carrier is transmitted from 
the transmitter unit by antenna 12. 
The oscillator 10 preferably generates a high frequency signal of 
predetermined frequency, for example, 27.125MH.sub.z. As will be seen, 
only two controls are required in the transmitting unit of FIG. 1, namely 
switch 16 and handle 20 affording thereby simple operation of the vehicle. 
It will be appreciated that when switch 16 is open, the handle 20 does not 
permit any control function. The multivibrator 14 for purpose of 
disclosure may generate a signal having a frequency ranging from 200 to 
2,000 H.sub.z. 
Referring to FIG. 2, there is shown a receiving unit adapted to receive the 
modulated or unmodulated signals transmitted thereto by the transmitter of 
FIG. 1 for controlling movement or stopping of the toy vehicle, i.e. 
forward, reverse, right or left steering movements and stopping. 
Antenna 22 receives the transmitted signal and supplies it to a super 
regenerative detector 24 which may be either a frequency discriminator, if 
a frequency modulated signal is transmitted from the receiver unit, or an 
amplitude demodulator, if an amplitude modulated signal is transmitted 
thereby. Connected in series with detector 24 is a low frequency amplifier 
26 for amplifying the demodulated signal and an oscillation amplitude 
limiter 28 which limits the amplitude of the output of the amplifier 26. 
As noted heretofore, vibrator 14 generates low frequency signals in the 
range of, for example, 200 to 2,000 H.sub.z. When a carrier signal is 
modulated at a selected frequency of the multivibrator and transmitted for 
reception by the receiver and demodulated therein for recovery of the 
modulating signal, the latter is applied as an output from the amplitude 
limiter 28 to a point 30 from which branches a low frequency band-pass 
filter constituting resistor 32 and condenser 34, and a high frequency 
band pass filter constituting condenser 38 and resistor 40. These 
band-pass filters are designed to provide the gain characteristics shown 
in FIG. 3. Thus, as will be seen in this Figure the output of the low-pass 
filter for signals between 200 to 1000 H.sub.z will be of uniform high 
value (solid line) but will progressively decrease, as shown by solid line 
36 at frequencies from above 1,000 H.sub.z to 2,000 H.sub.z. Conversely, 
the high band-pass filter will have a uniform high output at frequencies 
from above 1,000 to 2,000 H.sub.z (dotted line) and the output will 
progressively decrease, as shown by dotted line 42, at frequencies from 
below 1,000 to 2,000 H.sub.z. It will also be seen from FIG. 3 that at 
1,000 H.sub.z the outputs from the low and high band-pass filters are 
equal. Accordingly, when the demodulated signal at the output of detector 
24 is a 1,000 H.sub.z signal the outputs from the low frequency band-pass 
and high frequency band-pass filters will be equal. In this case, the 
wheels of the toy will be driven by the motors at the same speed so that 
the vehicle will move in a straight path. If the demodulated signal is a 
200 H.sub.z signal the output from the low frequency band-pass filter will 
be greater than the output from the high frequency band-pass filter. 
Conversely, if a 2,000 H.sub.z demodulated signal is passed through the 
filters the output from the high frequency band-pass filter will be 
greater than the output from the low frequency band-pass filters. The 
reduced outputs of the one or the other filter network operates to dampen 
that motor supplied with the lower output voltage. For this purpose, the 
output of, for example, the low frequency band-pass filter is connected to 
a voltage rectifying-amplifier 44 which in turn is connected with DC motor 
48 to drive a wheel 68 (FIG. 7) or ceterpillar tread 76 (FIG. 8). The 
output of the high frequency band-pass filter on the other hand is 
connected with a voltage rectifying-amplifier 46 which supplies a DC 
voltage to DC motor 50 to drive the wheel 70 (FIG. 7) or caterpillar tread 
78 (FIG. 8). It will be apparent that when the high frequency carrier is 
modulated at a frequency other than the exemplified 1,000 H.sub.z, the 
vehicle will be turned from its straight path movement due to the greater 
damping action on one of the motors than the other. 
Referring now to FIG. 4 which shows another embodiment of a single channel 
receiving unit in accordance with the invention, in which the same 
components are identified with the same reference numerals, there is shown 
additional circuitry interposed between elements 44 and 48 on the one hand 
and elements 46 and 50 on the other hand. The additional circuitry is 
intended to permit stopping and reversal of operation of motors 48 and 50 
to in turn stop and reverse rotation of the vehicle drive wheels or 
caterpillar tread 70. To this end amplifer 52 and a rotary relay or servo 
motor 54 are shown electrically connected by means of resistors to 
junctions 44a and 44b. Between junction 44a and motor 48 is connected 
switch 56 and between junction 44b and motor 50 is connected switch 58. 
These switches together with switch 59, connected to voltage source 64, 
are operated by rotary relay 54 in such manner tha when an output voltage 
appears at junctions 44a and 44b, as would occur when a modulated carrier 
is received at the receiver, the amplifier 52 is rendered inoperative. 
Rotary relay 54 is of the type which responds to changes in state of 
amplifier 52 to actuate for each change of state switches 56, 58 and 59. 
With switches 56, 58 and 59 positioned as shown in FIG. 4, the wheels of 
the vehicle will be driven by the voltage source 64 as modified by the 
voltage outputs derived from the low and high frequency band-pass filters. 
If switch 16 in the transmitter unit is opened an unmodulated carrier is 
transmitted by antenna 12 and received by the receiver unit. Receipt of an 
unmodulated wave by receiver unit will fail to produce a voltage at 
junctions 44a and 44b in which circumstance the operational state of the 
amplifier 52 is changed and becomes operative at which time rotary relay 
54 moves the movable arms of each of switches 56, 58 and 59 into 
engagement with the free contact of these switches to reverse operation of 
motors 48 and 50. If desired, switches 56, 58 and 59 may be replaced by 
rotary switches 60, 62 as shown in FIG. 5 which are operated by rotary 
relay 54 connected in circuit with amplifier 52 in the same manner as in 
the described circuit arrangement of FIG. 4. By using rotary switches 60, 
62 the vehicle can be advanced, stopped, reversed and again stopped as 
shown in FIG. 6, the precise order of course being subject to change 
according to the intended purpose. As in FIG. 4, the motors are energized 
by voltage source 64 damped by the output of the low and high frequency 
band-pass filters when a modulated carrier is received. 
FIG. 7 illustrates a travelling toy 66 provided at its front left side with 
the wheel 68 and at its front right side with the wheel 70 respectively 
driven by the motors 48 and 50 supported by a plate 72 which is pivotally 
mounted to a toy body 66 through a pivot 74. When there is a difference in 
the r.p.m. of the driven wheels 68 and 70, the vehicle will turn from a 
straight course. FIG. 8 shows a further embodiment of the toy, the 
advancing direction of which may be altered by merely varying the driving 
speed of the catapillar treads 76 and 78 as a function of the modulating 
frequency of the carrier. 
In the operation of the wireless control device according to the invention, 
a high frequency signal is generated by the high frequency oscillator 10. 
The high frequency may selectively be modulated by the multivibrator 14 at 
a frequency determined by the setting of resistors 18 by handle 20. The 
thus modulated high frequency signal when transmitted by the antenna 12, 
is received by the antenna 22 and detected by the super regenerative 
detector 24 the output of which is amplified by the low frequency 
amplifier 26. The output of amplifier 26 is supplied to the amplitude 
limiter 28, the output of which is simultaneously fed to the low-pass and 
the high-pass filters. For band-pass filters having the characteristics 
shown in FIG. 3, if a 1,000 H.sub.z demodulated signal is simultaneously 
fed to the band-pass filter networks of FIGS. 4 and 5, the output of each 
filter network will be substantially the same so that substantially the 
same damping factor is obtained in consequence of which motors 48 and 50 
will drive wheels 68 and 70 at substantially the same r.p.m. whereby to 
advance the toy in a straight line. 
Should the variable resistor 18 be adjusted by handle 20 at the transmitter 
to vary so that the frequency of the multivibrator 14 is lowered below the 
1,000 H.sub.z value, the signal passing through the low-pass filter will 
be dampened to a lesser degree than the signal which passes through the 
high-pass filter. In consequence, motor 48 will rotate at a higher r.p.m. 
than motor 50 so that the vehicle will now turn from its straight line 
movement as a function of the relative damping factors of the low and high 
band-pass filters. On the other hand, when the detected frequency from 
multivibrator 14 is higher than the exemplified 1,000 H.sub.z, the signal 
through the high-pass filter sustains a lower damping factor than it 
sustains in passing through the low pass filter so that motor 48 is 
rotated at a lower r.p.m. than motor 50 in consequence of which the 
vehicle is now moved from its straight line path (which it assumes at 
1,000 H.sub.z) to a direction opposite to that driven when the modulating 
frequency is below 1,000 H.sub.z. 
When the switch 16 is opened an unmodulted carrier is transmitted and 
received by the receiver. Accordingly, on receipt of the unmodulated 
signal there will be no output from detector 24, amplifier 26 or amplitude 
limiter 28. Amplifier 52 is designed to be operative in the absence of an 
input signal from the band-pass filters and to be inoperative in the 
presence of such signal, the latter signal being developed only on receipt 
of the modulated carrier. Rotary relay 54 is operated, in known manner, to 
advance one step at a time for each change of state of amplifier 52; i.e. 
conductive to non-conductive state and vice-versa. Since the operating 
state of amplifier 52 is effectively controlled by switch 16 it will be 
appreciated that the relay 54 will be advanced one step at a time each 
time switch 16 is moved from its closed to its open position and vice 
versa. Switches 60 and 62 associated with relay 54 are thus rotated and 
advanced one step at a time under control of relay 54. Accordingly, rotary 
switches 60 to 62 may be advanced first to position 80 then to the stop 
position 82, then to the reverse position 84 and again to the stopping 
position 86, all as shown in FIG. 6, the continuous operation of switches 
60 and 62 to these sequential positions being carried out under control of 
switch 16. 
As will now be appreciated, the objective of providing a low cost simple to 
operate remote control toy is fulfilled by the invention in requiring but 
a single channel receiver and transmitter the carrier of which, when 
modulated at predetermined frequencies, permits straight and turning 
movement of the toy vehicle and also enables stopping and reverse movement 
of the vehicle by the simple expedient of operating an on-off switch in 
the transmitting unit.