US3327138A - Signal gating circuit and vehicle starting control circuit - Google Patents

Description

June 20, 1967 R. D. SMiTH 3,327,138

SIGNAL GATING CIRCUIT AND VEHICLE STARTING CONTROL CIRCUIT Filed Aug. 21, 1964 K To ()ufpuf Circuif l/V'VE/V TOR. ROBERT 0. 554/ TH yW/M I A I forneys United States Patent 3,327,138 SIGNAL GATING CIRCUIT AND VEHICLE STARTING CONTROL CIRCUIT Robert D. Smith, Turtle Creek, Pa., assignor of one-half to Donald Heaton, Verona, Pa. Filed Aug. 21, 1964, Ser. No. 391,156 9 Claims. (Cl. 30788.5)

This invention relates to an improved signal gating circuit and more particularly to such a circuit for use as a motor vehicle starting control circuit.

Gating circuits have a wide variety of uses where only selected signals are desired to be passed to another circuit. While gatecircuits are not new per se, the present invention provides a unique time delay circuit for selectively passing a signal to an output circuit.

According to the invention a first input signal initiates a first time delay t of indeterminate duration after which time a second delay I is started and a feedback signal is generated. The latter signal signifies the start of the second time delay t of predetermined duration and signals the acceptability of a second input signal during a gate interval t after expiration of t but before expiration of t Expiration of the second time delay, absent the re-' ceipt of the second input signal, blocks or inhibits passage of the second input signal to an output circuit. Receipt of the second input signal before or after the gate interval z also blocks or inhibits passage of the second input signal to the output circuit. Stated differently, the circuit is such that the desired passage of a second input signal to an output circuit is possible only after receipt of a first signal and after the expiration of a first time delay but before expiration of a second time delay.

While the circuit herein is useful in numerous applications, the description hereafter will be largely addressed to one embodiment of the invention in a motor vehicle starting control circuit. Where the input signals referred to above are signals actuated by a vehicle operator and the output circuit is the motor vehicle starting circuitry, the device affords a means for inhibiting operation of the vehicle by an individual who cannot react to a stimulus within a predetermined time interval. The reaction times referred to are the minimum times for a human operator to produce a simple, non-choice response to a stimulus. in the particular application herein, the times refer to the minimum reaction time for an operator 'to turn an ignition key in response to a stimulus. Using a key ignition switch having an ON position and a momentary START position, corresponding to the firstand second input signals, it is apparent that the operator must successfully follow the sequence earlier described in order to start the vehicle. Thus, the ignition must first be switched to the ON position to initiate the indeterminate time delay t after which the operator is signaled to switch to the START position. The operator must respond to this signal Within the gate interval 1 to successfully actuate the starting circuitry. Failure to respond within the gate interval requires the operator to reinitiate the entire sequence. As will later be described more fully, attempts to preempt or out-guess the device are frustrated by the circu-it arrangement. The time delays and sequence of operation are chosen so as not to unduly burden an operator whose reaction times have not been impaired to the extent that they rise above a predetermined level, but at the same time present a test which cannot .be readily performed by a person whose ability to react has been so impaired.

An object of the present invention is to provide a new and useful signal gating circuit.

Another object is to provide a novel vehicle starting control circuit.

A further object is to provide such a circuit as will inhibit vehicle operation by an individual whose reaction times rise above a predetermined level.

These and other objects will be apparent to those skilled in the art and more readily understood by reference to the following description, wherein:

FIG. 1 is a schematic illustration of the circuit of the invention; and

FIG. 2 is a diagrammatic illustration of the relationship between the various time delays.

Referring to the drawing, one embodiment of the invention is illustrated. Power Supply 2 is the vehicle battery connected between terminals A and C (ground) and provides the power for operating the remaining components. Switch 3 is a standard type of double pole vehicle key ignition switch shown in OFF position, and has two active positions, ON and START. In the ON position, one pole 3a of the switch contacts terminal A; in the START position, the other pole 3b contacts terminal B while pole 3a maintains contact with terminal A, the latter terminal having junction points 4, 5, 6 and 7. A time delay relay 8 is connected at 4 across the terminals A and C and has normally open contacts 8a connected in series between 4 and 5 of terminal A and in parallel with relay 8, which is a thermal delay device selected so as to provide a delay time of approximately 1-10 seconds before closing the contacts 4a.

A relay 9, having contacts 9a in series with terminal B, is connected at one end to terminal A at 5 through a current limiting resistance having a positive temperature coefiicient such as a tungsten lamp 10, the other side of relay 9 being connected to terminal C. In parallel with relay 9, there is a silicon gate rectifier 11 having its anode connected to A through the lamp 10 and its cathode connected to C.

Between point 6 of terminal A and terminal C, there is connected a uni-junction transistor 12 having its basetwo region connected to A through resistor 13 and its base-one region connected to C through resistor 14 and also to the gate of rectifier 11. The emitter of transistor 1'2 is connected to A through a variable resistor 15, and is connected to C through capacitor 16 which is preferably an electrolytic capacitor exhibiting good stability despite variations in ambient temperatures, such as a tantalum capacitor. The RC time constant of resistor 15 and capacitor 16 is preferably adjustable through a range of from 200 to 500 milliseconds. The emitter of transistor 12 is further connected to the anode of diode 17 whose cathode is connected to A, at 7, through resistor 18 and also to the anode of silicon gate rectifier '19. The cathode of rectifier 19 is connected to A through a resistance having a positive temperature coeflicient such as tungsten lamp 20, and is also connected to C through resistor 21. The gate of rectifier 19 is connected to C through resistor 22. Across terminals B and C, there are two series resistors 23 and 24 having their junction 25 connected to C through capacitor 26 and diode 27' whose cathode is connected to C through resistor 22.

Operation is equal to the indeterminate time delay of relay 8.

, the output circuit and is equal to t less the time 1 re- Interval t is the precise time delay required to charge capacitor 16 to the firing potential of transistor 12. Interval t is that portion of t during which rectifier 19 must be gated to successfully pass a START signal to quired to heat the filament of bulb 20.

When switch 3 is placed in the ON position, thermal relay 8 is energized and closes contacts 8a after an indeterminate time delay. Closing of contacts 801 energizes relay 9 which immediately closes contacts 9a. Contacts 9a are physically located adjacent the ignition switch so that their closing produces a tactile feedback signal to the operator indicative of the expiration of the first delay t Other feedback signals, such as visual or aural signals, are possible by providing additional contacts on relays 8 or 9, for example, to actuate various types of indicators (not shown) as will be readily understood by those skilled in the art. Closing contacts 8a commences the charging of capacitor 16 through resistance 15 to initiate time delay t of approximately 300 milliseconds duration, and passes current through bulb 20 to commence a time delay t running concurrently with the time delay 1 When sufiicient time has elapsed to charge capacitor 16 to a potential sufiicient to drive transistor 12 into conduction, a pulse appears across baseone resistance 14 to fire or gate the rectifier 11 driving the latter into conduction. When rectifier 11 conducts, relay 9 is eifectively short-circuited, resulting in opening of contacts 9a to disable passage of a START signal to the output circuit. The circuit is then said to be in a NO-GO configuration.

On the other hand, if switch 3 is turned to the START position during the interval t rectifier 19 will be gated, thereby clamping the emitter of transistor 12 to a level insufiicient to produce a gate for rectifier 11. The explanation for this is that when contacts 8a close, diode 17 is reverse biased with a substantial positive voltage on its cathode, which voltage is greatly reduced when rectifier 19 is gated by the potential developed across resistor 22 when the switch 3 is placed in START position. Gating of rectifier 19 effectively provides a short circuit across capacitor 16 so the latter cannot charge to a voltage suflicient to drive unijunction transistor 12 into conduction to produce a gate pulse to fire rectifier 11. Thus contacts 9a remain closed and the circuit is said to be in a G configuration.

The operator is prevented from pre-empting the device because of the circuitry associated with the gating of rectifier 19. One obvious method of attempting to circumvent the safety features would be to simply turn switch 3 to the START position and hold it there while the first time delay runs out in the expectation of immediately gating rectifier 19. Such an attempt will not be successful as will now be explained. With the contacts 8a open and the switch 3 in START position, capacitor 26 will begin to charge through resistor 22 and diode 27. The charging time is made quite short and is determined by the size of the capacitor 26, resistors 22 and 23 and the forward resistance of diode 27 which are selected to provide a short RC time constant on the order of 1 millisecond, the total charge time being approximately milliseconds. Thus, the capacitor 26 would be rapidly charged so no gating pulse could be developed across resistor 22 to gate rectifier 19 when t expires.

Bulb 20 also serves to frustrate guessing by providing a time delay I;.; (equal to t t of approximately 200 milliseconds after the closing of contacts 8a, during which time rectifier 19 may not be gated; The resistance of bulb 20 and resistor 21 form a voltage divider for biasing the cathode of rectifier 19. The cold resistance of bulb 20 (approximately 3 ohms) is such that the cathode of rectifier 19 is biased by the potential across resistor 21 with a sufficiently large positive potential to prevent gating the rectifier even if a gating pulse is present. This biasing potential decays as the filament of bulb 20 heats to a resistance of approximately 45 ohms leaving only a small positive potential on the rectifier cathode thereby enabling a pulse developed across resistor 22 to gate rectifier 19. The time delay inherent in bulb 20 will not penalize the ordinary operator since that time has been found to be less than the minimum reaction time for most persons to respond to the signal received on closing of contacts 9a, thus only those who do not follow the prescribed sequence will be hampered by this delay.

A first unsuccessful attempt togate rectifier 19 will prevent immediate repeated attempts because of the long discharge time of capacitor 26. As has been already shown, no gate pulse can be developed when capacitor 26 is charged, and an unsuccessful attempt results in charging capacitor 26. This charge is removed only by the discharge of the capacitor through the high backward resistance of diode 27 and resistors 22 and 24. Alternatively, a high discharge resistance 28, shown in dotted lines, may be provided across the capacitor 26. The unsuccessful operator must therefore, wait for the capacitor to discharge, which may be about five seconds, before reinitiating the sequence. The switch 3 must be turned to the full OFF position to reinitiate the sequence in order at reset the now-conducting rectifier 11 to a non-conducting state by removing the anode voltage.

The rectifiers 19 and 11 together form a bi-stable state such that when either is gated before the other the circuit is locked in a G0 or NOGO configuration, respectively.

Once rectifier 19 is gated before rectifier 11, the operat-or may continue to switch back and forth between the ON and START positions to pass the START signal to the output circuit since the rectifier will continue to conduct and contacts 8a and 9a will remain closed.

The circuit herein described is not intended to be limited to the particular components shown in the embodiment nor to the particular application set forth. As will be obvious to those skilled in the art, numerous modifications and applications are possible within the scope and spirit of the invention disclosed.

I claim:

1. In a control circuit having input and output circuits and means for sequentially applying first and second input signals, the second input signal being applied after application of the first signal but during the duration of the first signal, a signal gating circuit comprising:

(a) first and second time delay means, the first delay means being actuated by the first input signal,

(b) means responsive to the expiration of the first time delay for actuating the second delay means, and

(c) gate means responsive to the first and second input signals and in circuit with the delay means for passing the second input signal to the output circuit only during the interval of the second time delay.

2. The circuit defined in claim 1, wherein the gate means comprises,

(a) first and second switching means, the first switching means inhibiting passage of the second signal to the output circuit when actuated, the second switching means being actuated by the second signal when the latter is received during the second delay interval, the actuation of the second switching means inhibiting actuation of the first switching means for permitting the passage of the second signal to the output circuit, and

(b) means actuating the first switching means on expiration of the second time delay interval.

3. The circuit defined in claim 2, wherein the first and second switching means are semi-conductor gate rectifiers and wherein the means actuating the first switching means comprises a uni-junction transistor having its output electrode connected to the gate of the first switching means and being connected so as to produce a gating pulse on the output electrode when the second delay interval expires.

4. The circuit defined in claim 1, including a third time delay means actuated by the means responsive to the expiration of the first time delay, for producing a time delay interval shorter than the second delay, and wherein the gate means passes the second input signal to the output circuit only during that portion of the second interval which extends beyond the third interval. 5. A vehicle starting control circuit having a power supply and an output starting circuit, comprising,

(a) an ignition switch having ON and START positions and being so arranged that when the switch is in the START position the switch remains also in its ON position,

(b) means in circuit with the switch for connecting and disconnecting the power supply to and from the output circuit through the START position, representing GO and NO-GO configurations respectively,

(c) first time delay means connected to be actuated when the switch is in ON position,

((1) second time delay means in circuit with the first delay means and connected to be actuated on expiration of the first delay, and

(e) bi-stable gate means in circuit with the switch and the first and second delay means for locking the circuit in the GO configuration when the switch is placed in START position during the interval of the second delay and for locking the circuit in the NO-GO configuration when the switch is positioned to its START position during an interval other than that of the second delay.

6. A vehicle starting control circuit having a power supply and an output starting circuit, comprising,

(a) an ignition switch having ON and START positions,

(b) means in circuit with the switch for connecting and disconnecting the power supply to and from the output circuit through the START position, representing GO and NO-GO configurations respectively,

(c) first time delay means connected to be actuated when the switch is in ON position,

(d) second and third time delay means in circuit with the first delay means and connected to be actuated on expiration of the first delay, the third delay interval being shorter than that of the second, the difference between the second and third delay intervals beirig a gate interval, and

(e) bi-stable gate means in circuit with the delay means for locking the circuit in the GO configuration when the switch is placed in START position during the gate interval and for locking the circuit in the NOGO configuration when the switch is turned to the START position other than during the gate interval.

7. The circuit as defined in claim 6 including means responsive to the expiration of the first time delay for generating a feedback signal for indicating to a vehicle operator the expiration of the first delay.

8. The circuit as defined in claim 7 wherein the first delay means is a thermal delay device having an indeterminate belay time, the second delay means comprises a series connected resistance and capacitance, and the third delay means is a resistance having a positive temperature coefiicient.

9. The device as defined in claim 8, wherein the bistable gate means comprises a uni-junction transistor having its emitter connected to the junction of the resistance and capacitance for roducing a pulse at the expiration of the second time delay, first electronic switching means connected to receive the pulse to lock the circuit in the NO-GO configuration, and second electronic switching means connected to be actuated when the ignition switch is turned to the START position during the gate interval for locking the circuit in a G0 configuration.

References Cited UNITED STATES PATENTS 3,158,758 11/1964 Pearson 30788.5 3,206,612 9/1965 Swanekamp et a1. 307-885 3,253,157 5/1966 Lemon 30788.5 3,267,382 8/1966 Adem 32872 ARTHUR GAUSS, Primary Examiner.

B. P. DAVIS, Assistant Examiner.

Claims (1)

1. IN A CONTROL CIRCUIT HAVING INPUT AND OUTPUT CIRCUITS AND MEANS FOR SEQUENTIALLY APPLYING FIRST AND SECOND INPUT SIGNALS, THE SECOND INPUT SIGNAL BEING APPLIED AFTER APPLICATION OF THE FIRST SIGNAL BUT DURING THE DURATION OF THE FIRST SIGNAL, A SIGNAL GATING CIRCUIT COMPRISING: (A) FIRST AND SECOND TIME DELAY MEANS, THE FIRST DELAY MEANS BEING ACTUATED BY THE FIRST INPUT SIGNAL, (B) MEANS RESPONSIVE TO THE EXPIRATION OF THE FIRST TIME DELAY FOR ACTUATING THE SECOND DELAY MEANS, AND (C) GATE MEANS RESPONSIVE TO THE FIRST AND SECOND INPUT SIGNALS AND IN CIRCUIT WITH THE DELAY MEANS FOR PASSING THE SECOND INPUT SIGNAL TO THE OUTPUT CIRCUIT ONLY DURING THE INTERVAL OF THE SECOND TIME DELAY.

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